U.S. patent application number 10/933447 was filed with the patent office on 2005-03-10 for expansion device.
This patent application is currently assigned to TGK CO., LTD.. Invention is credited to Hirota, Hisatoshi, Koyama, Katsumi, Tsugawa, Tokumi.
Application Number | 20050050916 10/933447 |
Document ID | / |
Family ID | 34138007 |
Filed Date | 2005-03-10 |
United States Patent
Application |
20050050916 |
Kind Code |
A1 |
Hirota, Hisatoshi ; et
al. |
March 10, 2005 |
Expansion device
Abstract
To provide an expansion device that is configured compact in
size and capable of effectively preventing an abnormal rise in
pressure within the expansion device caused by the differential
pressure across the expansion device. An expansion device according
to the present invention cancels part of refrigerant pressure by a
pressure-canceling structure. More specifically, by the amount of
pressure received by a valve-closing pressure-receiving surface,
the elastic force required of a spring can be reduced. As a result,
a small-sized spring can be employed as the spring, and the entire
expansion device can be made compact in construction. Further, when
the differential pressure across the expansion device has become
equal to or higher than a predetermined value, a relief mechanism
enables refrigerant flowing in from the upstream side to escape
into a passage other than a refrigerant passage through a valve
element. This makes is possible to prevent an abnormal rise in the
refrigerant pressure inside the expansion device, thereby
preventing breakage or the like of the internal components.
Inventors: |
Hirota, Hisatoshi; (Tokyo,
JP) ; Koyama, Katsumi; (Tokyo, JP) ; Tsugawa,
Tokumi; (Tokyo, JP) |
Correspondence
Address: |
WESTERMAN, HATTORI, DANIELS & ADRIAN, LLP
1250 CONNECTICUT AVENUE, NW
SUITE 700
WASHINGTON
DC
20036
US
|
Assignee: |
TGK CO., LTD.
Tokyo
JP
|
Family ID: |
34138007 |
Appl. No.: |
10/933447 |
Filed: |
September 3, 2004 |
Current U.S.
Class: |
62/527 ;
62/222 |
Current CPC
Class: |
F25B 2341/062 20130101;
F25B 41/31 20210101 |
Class at
Publication: |
062/527 ;
062/222 |
International
Class: |
F25B 041/00; F25B
041/04; F25B 041/06 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2003 |
JP |
2003-315493 |
Mar 12, 2004 |
JP |
2004-070947 |
Claims
What is claimed is:
1. An expansion device that is disposed in a flow passage of
refrigerant circulating through a refrigeration cycle, for passing
the refrigerant introduced from an upstream side thereof through an
internal refrigerant passage thereof to thereby cause decompression
of the refrigerant and allow the decompressed refrigerant to flow
downstream, and is equipped with a relief mechanism that is
operable when a differential pressure across the expansion device
has become equal to or higher than a predetermined value, to open a
flow passage other than the refrigerant passage which is closed by
a valve element urged by an elastic member disposed within the
expansion device, to thereby allow at least part of the refrigerant
flowing in from the upstream side to escape via the flow passage to
flow downstream, the expansion device comprising: a
pressure-cancelling structure that cancels part of pressure of the
refrigerant acting on the valve element in a valve-opening
direction.
2. An expansion device that is disposed in a flow passage of
refrigerant circulating through a refrigeration cycle, comprising:
a cylinder in the form of a hollow cylinder, the cylinder having a
valve seat formed by a stepped portion provided inside the hollow
cylinder; a valve element that has a body in the form of a hollow
cylinder, the valve element being movably inserted within the
cylinder, and including a valve portion that forms part of the body
and can be removably seated on the valve seat, and a refrigerant
passage extending through an inside of the body to allow passage of
the refrigerant; a restriction mechanism that decompresses the
refrigerant passing through the refrigerant passage; an elastic
member that is disposed within the cylinders for urging the valve
element in a valve-closing direction; a pressure-cancelling
structure that cancels at least part of pressure of the refrigerant
acting on the valve element in a valve-opening direction, the
pressure-cancelling structure comprising a valve-closing
pressure-receiving surface that receives pressure of the
refrigerant acting on the valve element in the valve-closing
direction and has a pressure-receiving area which is smaller than a
pressure-receiving area of a valve-opening pressure-receiving
surface that receives pressure of the refrigerant acting on the
valve element in the valve-opening direction; and a relief
mechanism that is operable when a differential pressure across the
expansion device has become equal to or higher than a predetermined
value to cause the valve portion to be moved away from the valve
seat, to allow at least part of the refrigerant flowing in from an
upstream side to escape into a flow passage other than the
refrigerant passage extending through the cylinder.
3. The expansion device according to claim 2, wherein, the valve
element includes a guided portion that is guided along an inner
peripheral surface of the cylinder when the valve element is moved
to and away from the valve seat.
4. The expansion device according to claim 2, wherein the cylinder
is directly fixed to an inside of the piping of the refrigeration
cycle.
5. The expansion device according to claim 3, comprising: a stepped
portion in the refrigerant passage of the valve element at which
the refrigerant passage is expanded in an upstream-to-downstream
direction; an inner shaft member in the form of a hollow cylinder
that has a flow-restricting portion formed therein, the
flow-restricting portion having a cross-section smaller than a
cross-section of the refrigerant passage, and is partially inserted
into an expanded side of the stepped portion of the valve element,
the inner shaft member protruding downstream from the valve
element, and functioning as the restriction mechanism; and a
stopper that is fixed to the cylinder, and configured to be capable
of having a downstream end of the inner shaft member engaged
thereat, the stopper being formed with a through hole having a
cross-section larger than a cross-section of the flow-restricting
portion, and wherein an internal space is formed between the inner
shaft member and the stepped portion, and the stepped portion forms
the valve-closing pressure-receiving surface.
6. The expansion device according to claim 5, wherein the stopper
is formed with at least one second through hole other than the
through hole, the second through hole communicating with the flow
passage other than the refrigerant passage, and wherein a flow
passage area of an entirety of the second through hole is larger
than a flow passage area of a gap formed between the valve portion
and the valve seat when the valve element is opened.
7. The expansion device according to claim 5, wherein the inner
shaft member is supported by the valve element, but not fixed to
any part of an internal structure of the cylinder.
8. The expansion device according to claim 5, wherein the cylinder
includes a small pipe portion that communicates with the
refrigerant passage when the valve element is seated on the valve
seat, and a large pipe portion that has a passage cross-section
larger than a passage cross-section of the small pipe portion, and
is configured such that the stepped portion is formed by the small
pipe portion and the large pipe portion, and wherein the
pressure-cancelling structure is formed by making the passage
cross-section of the small pipe portion larger than a cross-section
of the expanded side of the stepped portion of the valve
element.
9. The expansion device according to claim 5, wherein the guided
portion comprises a plurality of protruding portions extending from
the body toward an inner surface of the cylinder, the protruding
portions defining therebetween refrigerant flow passages that allow
passage of the refrigerant, and on the other hand, the stopper has
at least one second through hole formed around the through hole,
the second through hole communicating with the refrigerant flow
passages, and wherein when the valve portion is moved away from the
valve seat, the relief mechanism allows at least part of the
refrigerant flowing in from the upstream side to flow downstream
via a gap between the valve portion and the valve seat, the
refrigerant flow passages, and the second through hole.
10. The expansion device according to claim 5, wherein the elastic
member is interposed between the stopper and the valve element, the
expansion device comprising an adjusting mechanism that adjusts a
position of the stopper within the cylinder, and wherein an elastic
force of the elastic member can be adjusted by adjusting the
position of the stopper using the adjusting mechanism.
11. The expansion device according to claim. 3, wherein the
cylinder comprises: a valve seat portion in the form of a hollow
cylinder that is fixed to an inside of the cylinder as a separate
member, with one end thereof opening in an upstream direction, and
an opposite end thereof being formed with the valve seat, the valve
seat portion communicating with the refrigerant passage when the
valve element is seated thereon; a large pipe portion that has a
passage cross-section larger than a passage cross-section of the
valve seat portion, and has the valve portion inserted therein; and
a guide pipe portion that has the guided portion inserted therein
such that the guided portion is slidably supported therein, and has
a flow-restricting portion formed at a downstream end thereof, the
flow-restricting portion functioning as the restriction mechanism,
and wherein the pressure-cancelling structure is formed by making
the passage cross-section of the valve seat portion larger than a
passage cross-section of the guide pipe portion.
12. The expansion device according to claim 11, wherein the guide
pipe portion and the large pipe portion are configured to define a
refrigerant flow passage that allows passage of the refrigerant,
between the guide pipe portion and the large pipe portion, and the
piping of the refrigeration cycle, and wherein the large pipe
portion has a side wall formed with at least one communication hole
for causing an inside thereof to communicate with the refrigerant
flow passage, and wherein the relief mechanism allows at least part
of the refrigerant flowing in from the upstream side to flow
downstream via a gap between the valve portion and the valve seat,
the communication hole, and the refrigerant flow passage.
13. The expansion device according to claim 11, comprising an
adjusting mechanism that adjusts a position of the valve seat
portion within the cylinder, and wherein an elastic force of the
elastic member can be adjusted via the valve element by adjusting
the position of the valve seat portion using the adjusting
mechanism.
14. The expansion device according to claim 3, wherein the cylinder
has an introducing hole formed through a side wall thereof, for
allowing the refrigerant to be introduced therein, and includes a
small pipe portion that slidably supports the guided portion, and a
large pipe portion that has a passage cross-section larger than a
passage cross-section of the small pipe portion, and has the valve
portion inserted therein, and wherein at a pipe portion of the
valve element between the guided portion and the valve portion, a
space portion is formed between the valve element and the small
pipe portion, for communicating with the introducing hole, and
wherein the pipe portion has an orifice hole formed through a side
wall thereof, the orifice hole communicating between the space
portion and the refrigerant passage, and functioning as the
restriction mechanism, and wherein when the valve element is
seated, the refrigerant flowing in via the piping of the
refrigeration cycle is introduced into the refrigerant passage via
the introducing hole and the orifice hole, and wherein the
pressure-canceling structure is formed by forming an expanded pipe
portion in the small pipe portion, at a location in the vicinity of
the valve seat.
15. The expansion device according to claim 14, wherein the relief
mechanism is operable when the valve portion is moved away from the
valve seat, to allow at least part of the refrigerant flowing in
from the upstream side to flow downstream via the space portion,
and a gap between the valve portion and the valve seat.
16. The expansion device: according to claim 14, comprising: a
stopper in the form of a hollow cylinder that is fixed to the
cylinder, the elastic member being interposed between the stopper
and the valve element; an adjusting mechanism that adjusts a
position of the stopper within the cylinder, and wherein an elastic
force of the elastic member can be adjusted by adjusting the
position of the stopper using the adjusting mechanism.
17. The expansion device according to claim 2, wherein the cylinder
comprises a small pipe portion that communicates with the
refrigerant passage when the valve element is seated on the valve
seat, and a large pipe portion that has a passage cross-section
larger than a passage cross-section of the small pipe portion, and
has the valve element inserted therein, the small pipe portion and
the large pipe portion forming the stepped portion, and wherein, an
upstream end of the valve element is configured such that the
upstream end is fitted into the small pipe portion by a
predetermined amount when the valve element is seated, and the
upstream end has a side wall formed with at least one slit opening
toward the small pipe portion, and wherein the relief mechanism is
configured such that when the valve portion is moved away from the
valve seat, the slit progressively increases an opening that
communicates between the small pipe portion and the large pipe
portion, and when the upstream end of the valve element is removed
from the small pipe portion, the opening is rapidly increased,
thereby allowing at least part of the refrigerant flowing in from
the upstream side to stepwise escape into the flow passage other
than the refrigerant passage extending through the cylinder to
thereby allow the refrigerant to flow downstream.
18. The expansion device according to claim 17, comprising: a
stopper in the form of a hollow cylinder that is fixed to the
cylinders, the elastic member being interposed between the stopper
and the valve element; an adjusting mechanism that adjusts a
position of the stopper within the cylinder, and wherein an elastic
force of the elastic member can be adjusted by adjusting the
position of the stopper using the adjusting mechanism.
19. The expansion device according to claim 2, wherein the valve
element having the pressure-cancelling structure, the elastic
member urging the valve element, and the relief mechanism are
provided in a plurality of stages, from the upstream side to a
downstream side within the cylinder, and wherein the relief
mechanisms are configured to stepwise operate by adjusting
respective elastic forces of the elastic members urging the valve
elements.
20. An expansion device that is disposed in a flow passage of
refrigerant circulating through a refrigeration cycle, comprising:
a cylinder in the form of a hollow cylinder, the cylinder having a
first valve seat formed by a stepped portion provided inside the
hollow cylinder; a first valve element that has a body in the form
of a hollow cylinder inserted in the cylinder, and includes a valve
portion that forms part of the body and can be removably seated on
the first valve seat, a guided portion that is guided along an
inner peripheral surface of the cylinder when the body is moved to
and away from the first valve seat, and a first refrigerant passage
that extends through an inside of the body and has a stepped
portion formed therein at which the first refrigerant passage is
expanded in an upstream-to-downstream direction, the first
refrigerant passage allowing passage of the refrigerant; a first
elastic member that is disposed within the, cylinder, for urging
the first valve element in a valve-closing direction; a
pressure-cancelling structure that cancels at least part of
pressure of the refrigerant acting on the first valve element in a
valve-opening direction, the pressure-cancelling structure,
comprising a valve-closing pressure-receiving surface that receives
pressure of the refrigerant acting on the first valve element in
the valve-closing direction and has a pressure-receiving area
smaller than a pressure-receiving area of a valve-opening
pressure-receiving surface that receives pressure of the
refrigerant acting on the first valve element in the valve-opening
direction; a first relief mechanism that is operable when a
differential, pressure across the expansion device has become equal
to or higher than a first predetermined value to cause the valve
portion to be moved away from the first valve seat, to allow at
least part of the refrigerant flowing in from an upstream side to
escape into a flow passage other than the first refrigerant passage
within the cylinder to thereby allow the refrigerant to flow
downstream; an inner shaft member in the form of a hollow cylinder
that is formed therein with a flow-restricting portion having a
cross-section smaller than a cross-section of the first refrigerant
passage, and is partially inserted into an expanded side of the
stepped portion of the first valve element, the inner shaft member
protruding downstream from the first valve element; an inner
cylinder in the form of a hollow cylinder that is fixed to an
inside of the cylinder, and has at least one slit formed through a
side wall of an upstream end thereof, the upstream end being
capable of having a downstream end of the inner shaft member
engaged thereat, the inner cylinder being formed with a
communication hole extending therethrough for communication with
the flow-restricting portion; a second valve element that has a
body in the form of a hollow cylinder inserted in the inner
cylinder, the second valve element including a valve portion that
forms part of the body of the second valve element and can be
removably seated on a second valve seat formed on a downstream end
face of the inner shaft member, a guided portion that is guided
along the communication hole when the body of the second valve
element is moved to and away from the second valve seat, and a
second refrigerant passage that extends through an inside of the
body of the second valve element and has a cross-section smaller
than the cross-section of the flow-restricting portion; a second
elastic member that is disposed within the inner cylinder, for
urging the second valve element in a valve-closing direction; and a
second relief mechanism that is operable when the differential
pressure across the expansion device has become equal to or higher
than a second predetermined value smaller than the first
predetermined value to cause the valve portion of the second valve
element to be moved away from the second valve seat, to allow at
least part of the refrigerant flowing in from the upstream side to
escape into a flow passage other than the second refrigerant
passage within the inner cylinder to thereby allow the refrigerant
to flow downstream.
21. The expansion device according to claim 20, wherein an amount
of refrigerant allowed to escape by the first relief mechanism is
larger than an amount of refrigerant allowed to escape by the
second relief mechanism.
22. The expansion device according to claim 20, wherein the first
elastic member is interposed between the inner cylinder and the
first valve element, the expansion device comprising an adjusting
mechanism that adjusts a position of the inner cylinder within the
cylinder, and wherein an elastic force of the first elastic member
can be adjusted by adjusting the position of the inner cylinder
using the adjusting mechanism.
23. The expansion device according to claim 20, comprising: a
stopper in the form of a hollow cylinder that is fixed to the inner
cylinder, the second elastic member being interposed between the
stopper and the second valve element; and a second adjusting
mechanism that adjusts a position of the stopper within the inner
cylinder, and wherein an elastic force of the second elastic member
can be adjusted by adjusting a position of the stopper using the
second adjusting mechanism.
24. The expansion device according to claim 5, wherein the valve
element having the pressure-cancelling structure, the elastic
member urging the valve element, the relief mechanism, the inner
shaft member, and the stopper are provided in two stages, from the
upstream side to a downstream side within the cylinder, and wherein
a valve seat is formed on a downstream end face of the stopper
interposed between the two valve elements, for allowing a valve
portion of the valve element on a downstream side to be seated
thereon, wherein the elastic members are interposed between the
stoppers and the valve elements, respectively, the expansion device
comprising adjusting mechanisms that adjust respective positions of
the stoppers within the cylinder, and wherein elastic forces of the
elastic members can be adjusted by adjusting the positions of the
stoppers using the adjusting mechanisms, respectively.
25. The expansion device according to claim 2, wherein, the
cylinder includes a small pipe portion that communicates with the
refrigerant passage when the valve element is seated on the valve
seat, and a large pipe portion that has a passage cross-section
larger than a passage cross-section of the small pipe portion, and
has the valve element inserted therein, the stepped portion being
formed by the small pipe portion and the large, pipe portion, and
wherein when the valve element is seated, an upstream end of the
valve element is inserted into the small pipe portion with a
predetermined spacing from an inner wall of the small pipe potion,
and wherein when the valve portion is moved away from the valve
seat, until the upstream end of the valve element is removed from
the small pipe portion, the relief mechanism allows part of the
refrigerant flowing in from the upstream side to leak via the gap,
and when the upstream end of the valve element has been removed
from the small pipe portion, the relief mechanism allows the
refrigerant to escape at a larger flow rate, whereby the
refrigerant is allowed to stepwise escape into the flow passage
other than the refrigerant passage through the cylinder to thereby
allow the refrigerant to flow downstream.
26. The expansion device according to claim 25, comprising: a
stopper in the form of a hollow cylinder that is fixed to the
cylinder, the elastic member being interposed between the stopper
and the valve element; an adjusting mechanism that adjusts a
position of the stopper within the cylinder, and wherein an elastic
force of the elastic member can be adjusted by adjusting the
position of the stopper using the adjusting mechanism.
27. The expansion device according to claim 2, wherein the valve
element has a side wall formed with at least one communication hole
for communicating between an inside and an outside of the
refrigerant passage, and wherein the relief mechanisms includes a
flow passage-switching structure that switches between flow
passages of the refrigerant by opening or closing the communication
hole according to movement of the valve element.
28. The expansion device according to claim 27, wherein the
cylinder includes a small pipe portion that communicates with the
refrigerant passage when the valve element is seated on the valve
seat, and a large pipe portion that has a passage cross-section
larger than a passage cross-section of the small pipe portion, and
has the valve element inserted therein, the stepped portion being
formed by the small pipe portion and the large pipe portion, and
wherein an upstream end of the valve element is inserted inside an
inner wall of the small pipe portion by a predetermined amount when
the valve element is seated, and wherein the relief mechanism opens
the communication hole to allow the refrigerant to escape, when the
valve element is seated, and the relief mechanism keeps the
communication hole closed until the upstream end is removed from
the small pipe portion, when the valve portion is moved away from
the valve seat, and wherein when the upstream end of the valve
element is moved away from the small pipe portion, at least part of
the refrigerant flowing in from the upstream side is allowed to
escape into the flow passage other than the refrigerant passage
through the cylinder to flow downstream.
29. The expansion device according to claim 27, comprising: a
stopper in the form of a hollow cylinder that is fixed to the
cylinder, the elastic member being interposed between the stopper
and the valve element; an adjusting mechanism that adjusts a
position of the stopper within the cylinder, and wherein an elastic
force of the elastic member can be adjusted by adjusting the
position of the stopper using the adjusting mechanism.
30. The expansion device according to claim 5, wherein the valve
element having the pressure-cancelling structure, the elastic
member urging the valve element, and the relief mechanism, the
inner shaft member, and the stopper are provided in a plurality of
stages, from the upstream side to a downstream side within the
cylinder, wherein on a downstream end face of one of the stoppers
interposed between the valve elements, there is formed a valve seat
for allowing the valve portion of one of the valve elements on a
downstream side of the stopper to be seated thereon, wherein the
elastic members are interposed between the stoppers and the valve
elements, respectively, the expansion device comprising adjusting
mechanisms that adjust positions of the stoppers within the
cylinder, respectively, the relief mechanisms are configured to
sequentially operates from the downstream side, in a stepwise
manner, by adjusting elastic forces of the elastic members by
adjusting the positions of the stoppers, using the adjusting
mechanisms, respectively, and wherein the valve element on the
downstream side has a side wall formed with at least one
communication hole for communicating between an inside and an
outside of the refrigerant passage, and wherein a flow
passage-switching structure is provided which switches the flow
passage of the refrigerant by opening or closing the communication
hole according to the movement of the valve element formed with the
communication hole.
31. The expansion device according to claim 30, wherein the flow
passage-switching mechanism causes the communication hole to be
once closed during a process of rise in the differential pressure
across the expansion device.
32. An expansion device that is disposed in a flow passage of
refrigerant circulating through a refrigeration cycle, comprising:
a cylinder in the form of a hollow cylinder that has a valve seat
formed therein; a valve element that has a body in the form of a
hollow cylinder that is movably inserted in the cylinder and can
define a refrigerant passage for allowing passage of refrigerant
through the cylinder, the body having a portion forming a valve
portion that can be moved to and away from the valve seat; a
restriction mechanism that decompresses the refrigerant passing
through the refrigerant passage; an elastic member that is disposed
within the cylinder, for urging the valve element in a
valve-closing direction; a pressure-cancelling structure that
cancels part of pressure of the-refrigerant acting on the-valve
element in a valve-opening direction, the pressure-cancelling
structure comprising a valve-opening pressure-receiving surface
that receives pressure of the refrigerant acting on the valve
element in the valve-opening direction, and a valve-closing
pressure-receiving surface that receives pressure of the
refrigerant acting on the valve element in the valve-closing
direction; and a relief mechanism that is operable when the
differential pressure across the expansion device has become equal
to or higher than a predetermined value to cause the valve portion
to be moved away from the valve seat, to open a flow passage other
than the refrigerant passage extending through the cylinder by way
of the restriction mechanism, to thereby allow at least part of the
refrigerant flowing in from the upstream side to escape into the
flow passage other than the refrigerant passage to flow
downstream.
33. The expansion device according to claim 32, wherein the valve
seat is formed by a stepped portion formed inside the cylinder, and
the valve-opening pressure-receiving surface and the valve-closing
pressure-receiving surface of the valve element are both formed on
an upstream side of the restriction mechanism, and wherein the
restriction mechanism is formed by a gap between a reduced pipe
portion provided downstream of the body of the valve element, and a
shaft-like member partially inserted into the reduced pipe
portion.
34. The expansion device according to claim 33, wherein the
valve-opening pressure-receiving surface is formed also by an
upstream end face of the reduced pipe portion, and a
cross-sectional shape of the reduced pipe portion is configured
such that a pressure-receiving area of an entirety of the
valve-opening pressure-receiving surface becomes larger than a
pressure-receiving area of an entirety of the valve-closing
pressure-receiving surface.
35. The expansion device according to claim 33, wherein the
restriction mechanism comprises a restriction flow passage formed
by a gap between an inner peripheral end edge of the reduced pipe
portion and an outer peripheral surface of the shaft-like member,
and wherein a passage cross-section of the restriction flow passage
is changed in an increasing direction, when the valve element
operates in a valve-opening direction.
36. The expansion device: according to claim 35, wherein an
upstream end of the shaft-like member is formed with a tapered
portion a cross-section of which increases upstream, and the
restriction flow passage is formed between a tapered surface of the
tapered portion and an inner peripheral end edge of the reduced
pipe portion.
37. The expansion device according to claim 36, comprising an
engaging member that is supported within the cylinder, and has the
shaft-like member engaged at a downstream end thereof; and an
adjusting mechanism that adjusts a position of the engaging member
within the cylinder, and wherein a passage cross-section of the
restriction passage in a closed state of the valve element can be
adjusted by adjusting a position of the shaft-like member by moving
forward or backward the engaging member using the adjusting
mechanism.
38. The expansion device according to claim 32, wherein the
cylinder has a small pipe portion, and a large pipe portion, formed
therein in an upstream-to-downstream order, by expanding an inside
thereof toward the downstream side, and wherein the valve seat is
supported within the large pipe portion, and wherein the valve
element is formed with the valve portion in the form of a hollow
cylinder at a location downstream of the body, and has a reduced
pipe portion extended upstream of the body such that the reduced
pipe portion is movably inserted into the small pipe portion, and
wherein the restriction mechanism is formed by a gap between the
reduced pipe portion of the valve element and the small pipe
portion of the cylinder.
39. The expansion device according to claim 38, wherein the
valve-closing pressure-receiving surface is formed by an upstream
end face of the reduced pipe portion, and the valve-closing
pressure-receiving surface having a pressure-receiving area larger
than a pressure-receiving area of the valve-closing
pressure-receiving surface is formed by a downstream facing surface
of a stepped portion formed inside the body by the reduced pipe
portion.
40. The expansion device according to claim 39, wherein a
downstream facing surface having a cross-section larger than a
cross-section of the valve portion is formed on a downstream side
of the valve portion of the valve element, in a manner continuous
therewith.
41. The expansion device according to claim 32, wherein the
cylinder has a small pipe portion, and a large pipe portion, formed
therein in an upstream-to-downstream order, by expanding an inside
thereof in a upstream-to-downstream direction, and the expansion
device including a guide pipe in the form of a bottomed hollow
cylinder formed such that the guide pipe extends downstream from a
downstream opening portion of the small pipe, with a downstream end
thereof closed, and a communication hole formed through a side wall
thereof in the vicinity of the downstream end, for communicating
between an inside and an outside of the guide pipe, the guide pipe
having the valve element slidably fitted thereon, and wherein the
valve element has, on an upstream side thereof, a guided portion
that is slidable along an outer peripheral surface of the guide
pipe, and has a forward end face which can be engaged at a
downstream facing surface of a stepped portion provided at a
boundary between the small pipe portion and the large pipe portion,
and the valve element is formed with a reduced pipe portion at a
downstream end thereof, thereby defining a space portion for
communicating with the communication hole, between the reduced pipe
portion and the guided portion, and wherein in the space portion,
the valve-closing pressure-receiving surface is formed by a
downstream facing surface of the guided portion, and the
valve-opening pressure-receiving surface larger in
pressure-receiving area than the valve-closing pressure-receiving
surface is formed by an upstream end face of the reduced pipe
portion, and wherein when the valve element is close to the valve
seat, a gap between the reduced pipe portion of the valve element
and the guide pipe forms a restriction passage as the restriction
mechanism, and wherein the relief mechanism expands an opening area
of the gap between the reduced pipe portion and the guide pipe
against an urging force of the elastic member, to thereby allow the
refrigerant flowing in from the upstream side to escape downstream
at a larger flow rate.
42. The expansion device according to claim 41, wherein a
downstream end of the guide pipe is formed with a tapered portion a
cross-section of which decreases downstream, and the restriction
flow passage is formed between a tapered surface of the tapered
portion and an inner peripheral end edge of the reduced pipe
portion.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS, IF ANY
[0001] This application claims priority of Japanese Application No.
2003-315493 filed on Sep. 8, 2003 and entitled "EXPANSION DEVICE"
and No. 2004-070947 filed on Mar. 12, 2004, entitled "EXPANSION
DEVICE".
BACKGROUND OF THE INVENTION
[0002] (1) Field of the Invention
[0003] The present invention relates to an expansion device that is
disposed in a flow passage of refrigerant circulating through a
refrigeration cycle, and comprises a differential pressure valve
for controlling differential pressure thereacross.
[0004] (2) Description of the Related Art
[0005] Conventionally, a refrigeration cycle for an automotive
air-conditioner is known which uses an accumulator that performs
gas/liquid separation by storing excess refrigerant on an outlet
side of an evaporator, and an expansion device of a supercooling
degree control type that comprises an orifice (restriction flow
passage) that controls the flow rate of refrigerant in response to
changes in the supercooling degree and dryness of high-pressure
refrigerant flowing out from a condenser, and a differential
pressure valve that provides control such that a predetermined
degree of supercooling of the refrigerant is obtained (e.g.
Japanese Unexamined Patent Publication (Kokai) No. H11-257802).
[0006] The expansion device of this type comprises a cylinder fixed
within piping of the refrigeration cycle, and a valve element
disposed within the cylinder. The valve element slides within the
cylinder while being supported by a compression spring or the like.
Refrigerant passages, including a predetermined orifice, are formed
at a boundary between the inside of the valve element and the
cylinder such that movement of the valve element within the
cylinder in response to a change in the differential pressure
across the expansion device causes a change in the flow passage of
refrigerant. That is, so long as the differential pressure across
the expansion device is small, the flow passage of refrigerant is
set to the predetermined orifice, and when the differential
pressure has become equal to or higher than a predetermined value,
a flow passage of refrigerant is added to thereby prevent an
abnormal rise in the pressure of refrigerant.
[0007] Further, from the viewpoint of preventing an abnormal rise
in the pressure within the expansion device to protect the internal
components thereof, a safety rapture plate formed by a thin plate
is provided in part of the cylinder in advance, and when the
differential pressure has become equal to or higher than a
predetermined value, rupture of the plate is caused to relieve the
pressure.
[0008] However, in the above-described configuration of the
expansion device, to enable the valve element to normally operate
under high-pressure conditions, it is necessary to secure the
elastic force of the compression spring or the like, and hence a
large-sized compression spring need be used. This increases the
size of the entire expansion device, resulting in increased
manufacturing costs thereof.
SUMMARY OF THE INVENTION
[0009] The present invention has been made in view of these points,
and an object thereof is to provide an expansion device that is
configured compact in size and capable of effectively preventing an
abnormal rise in pressure within the expansion device caused by the
differential pressure across the expansion device.
[0010] To solve the above problems, the present invention provides
an expansion device that is disposed in a flow passage of
refrigerant circulating through a refrigeration cycle, for passing
the refrigerant introduced from an upstream side thereof through an
internal refrigerant passage thereof to thereby cause decompression
of the refrigerant and allow the decompressed refrigerant to flow
downstream, and is equipped with a relief mechanism that is
operable when a differential pressure across the expansion device
has become equal to or higher than a predetermined value, to open a
flow passage other than the refrigerant passage which is closed by
a valve element urged by an elastic member disposed within the
expansion device, to thereby allow at least part of the refrigerant
flowing in from the upstream side to escape via the flow passage to
flow downstream, the expansion device comprising a
pressure-cancelling structure that cancels part of pressure of the
refrigerant acting on the valve element in a valve-opening
direction.
[0011] Further, the present invention provides an expansion device
that is disposed in a flow passage of refrigerant circulating
through a refrigeration cycle, comprising a cylinder in the form of
a hollow cylinder, the cylinder having a first valve seat formed by
a stepped portion provided inside the hollow cylinder, a first
valve element that has a body in the form of a hollow cylinder
inserted in the cylinder, and includes a valve portion that forms
part of the body and can be removably seated on the first valve
seat, a guided portion that is guided along an inner peripheral
surface of the cylinder when the body is moved to and away from the
first valve seat, and a first refrigerant passage that extends
through an inside of the body and has a stepped portion formed
therein at which the first refrigerant passage is expanded in an
upstream-to-downstream direction, the first refrigerant passage
allowing passage of the refrigerant, a first elastic member that is
disposed within the cylinder, for urging the first valve element in
a valve-closing direction, a pressure-cancelling structure that
cancels at least part of pressure of the refrigerant acting on the
first valve element in a valve-opening direction, the
pressure-cancelling structure comprising a valve-closing
pressure-receiving surface that receives pressure of the
refrigerant acting on the first valve element in the valve-closing
direction and has a pressure-receiving area smaller than a
pressure-receiving area of a valve-opening pressure-receiving
surface that receives pressure of the refrigerant acting on the
first valve element in the valve-opening direction, a first relief
mechanism that is operable when a differential pressure across the
expansion device has become equal to or higher than a first
predetermined value to cause the valve portion to be moved away
from the first valve seat, to allow at least part of the
refrigerant flowing in from an upstream side to escape into a flow
passage other than the first refrigerant passage within the
cylinder to thereby allow the refrigerant to flow downstream, an
inner shaft member in the form of a hollow cylinder that is formed
therein with a flow-restricting portion having a cross-section
smaller than a cross-section of the first refrigerant passage, and
is partially inserted into an expanded side of the stepped portion
of the first valve element, the inner shaft member protruding
downstream from the first valve element, an inner cylinder in the
form of a hollow cylinder that is fixed to an inside of the
cylinder, and has at least one slit formed through a side wall of
an upstream end thereof, the upstream end being capable of having a
downstream end of the inner shaft member engaged thereat, the inner
cylinder being formed with a communication hole extending
therethrough for communication with the flow-restricting portion, a
second valve element that has a body in the form of a hollow
cylinder inserted in the inner cylinder, the second valve element
including a valve portion that forms part of the body of the second
valve element and can be removably seated on a second valve seat
formed on a downstream end face of the inner shaft member, a guided
portion that is guided along the communication hole when the body
of the second valve element is moved to and away from the second
valve seat, and a second refrigerant passage that extends through
an inside of the body of the second valve element and has a
cross-section smaller than the cross-section of the
flow-restricting portion, a second elastic member that is disposed
within the inner cylinder, for urging the second valve element in a
valve-closing direction, and a second relief mechanism that is
operable when the differential pressure across the expansion device
has become equal to or higher than a second predetermined value
smaller than the first predetermined value to cause the valve
portion of the second valve element to be moved away from the
second valve seat, to allow at least part of the refrigerant
flowing in from the upstream side to escape into a flow passage
other than the second refrigerant passage within the inner cylinder
to thereby allow the refrigerant to flow downstream.
[0012] The above and other objects, features and advantages of the
present invention will become apparent from the following
description when taken in conjunction with the accompanying
drawings which illustrate preferred embodiments of the present
invention by way of example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an explanatory view showing an expansion device
according to a first embodiment, in a state disposed in piping of a
refrigeration cycle.
[0014] FIGS. 2A and 2B are longitudinal cross-sectional views of
the expansion device.
[0015] FIGS. 3A and 3B are transverse cross-sectional views of the
expansion device.
[0016] FIG. 4 is an explanatory view showing the relationship
between the differential pressure across the expansion device and
the opening area of the refrigerant passage therethrough.
[0017] FIGS. 5A, 5B and 5C are cross-sectional views of an
expansion device according to a second embodiment.
[0018] FIGS. 6A, 6B and 6C are cross-sectional views of an
expansion device according to a third embodiment.
[0019] FIGS. 7A, 7B and 7C are longitudinal cross-sectional views
of an expansion device according to a fourth embodiment.
[0020] FIG. 8 is a cross-sectional view taken on line E-E of FIG.
7A.
[0021] FIG. 9 is an explanatory view showing the relationship
between the differential pressure across the expansion device and
the opening area of the refrigerant passage therethrough.
[0022] FIGS. 10A, 10B and 10C are longitudinal cross-sectional
views of an expansion device according to a fifth embodiment.
[0023] FIGS. 11A, 11B and 11C are longitudinal cross-sectional
views of an expansion device according to a sixth embodiment.
[0024] FIG. 12A to 12E are cross-sectional views of the
configuration of an inner cylinder as a component element of the
expansion device.
[0025] FIGS. 13A, 13B and 13C are longitudinal cross-sectional
views of an expansion device according to a seventh embodiment.
[0026] FIG. 14 is a cross-sectional view taken on line G-G of FIG.
13A.
[0027] FIGS. 15A, 15B and 15C are longitudinal cross-sectional
views of an expansion device according to an eighth embodiment.
[0028] FIG. 16 is an explanatory view showing the relationship
between the differential pressure across the expansion device and
the opening area of the refrigerant passage therethrough.
[0029] FIGS. 17A, 17B and 17C are longitudinal cross-sectional
views of an expansion device according to a ninth embodiment.
[0030] FIG. 18 is a cross-sectional view taken on line H-H of FIG.
17A.
[0031] FIG. 19 is an explanatory view showing the relationship
between the differential pressure across the expansion device and
the opening area of the refrigerant passage therethrough.
[0032] FIGS. 20A, 20B and 20C are longitudinal cross-sectional
views of an expansion device according to a tenth embodiment.
[0033] FIG. 21 is a cross-sectional view taken on line I-I of FIG.
20A.
[0034] FIGS. 22A, 22B and 22C are longitudinal cross-sectional
views of an expansion device according to an eleventh
embodiment.
[0035] FIG. 23 is a cross-sectional view taken on line J-J of FIG.
22A.
[0036] FIG. 24 is an explanatory view showing the relationship
between the differential pressure across the expansion device and
the opening area of the refrigerant passage therethrough.
[0037] FIGS. 25A and 25B are longitudinal cross-sectional views of
an expansion device according to a twelfth embodiment.
[0038] FIGS. 26A and 26B are transverse cross-sectional views of an
expansion device according to the twelfth embodiment.
[0039] FIGS. 27A, 27B and 27C are cross-sectional views of an
expansion device according to a thirteenth embodiment.
[0040] FIGS. 28A, 28B and 28C are longitudinal cross-sectional
views of an expansion device according to a fourteenth
embodiment.
[0041] FIG. 29 is a cross-sectional view taken on line N-N of FIG.
28A.
[0042] FIGS. 30A, 30B and 30C are longitudinal cross-sectional
views of an expansion device according to a fifteenth
embodiment.
[0043] FIGS. 31A and 31B are longitudinal cross-sectional views of
an expansion device according to a sixteenth embodiment.
[0044] FIGS. 32A and 32B are longitudinal cross-sectional views of
an expansion device according to a seventeenth embodiment.
[0045] FIGS. 33A and 33B are transverse cross-sectional views of an
expansion device according to the seventeenth embodiment.
[0046] FIGS. 34A, 34B and 34C are explanatory views showing the
configuration of a restriction mechanism.
[0047] FIG. 35 is an explanatory view showing the relationship
between the differential pressure across the expansion device and
the opening area of the refrigerant passage therethrough.
[0048] FIGS. 36A and 36B are longitudinal cross-sectional views of
an expansion device according to an eighteenth embodiment.
[0049] FIGS. 37A and 37B are transverse cross-sectional views of an
expansion device according to the eighteenth embodiment.
[0050] FIGS. 38A and 38B are longitudinal cross-sectional views of
an expansion device according to a nineteenth embodiment.
[0051] FIGS. 39A and 39B are transverse cross-sectional views of an
expansion device according to the nineteenth embodiment.
[0052] FIG. 40 is an explanatory view showing the relationship
between the differential pressure across the expansion device and
the opening area of the refrigerant passage therethrough.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0053] Hereinafter, embodiments of the present invention will be
described in detail with reference to the drawings.
First Embodiment
[0054] First, a first embodiment of the present invention will be
described. FIG. 1 is an explanatory view showing an expansion
device according to the present embodiment disposed in piping of a
refrigeration cycle. FIGS. 2A and 2B are longitudinal
cross-sectional views of the expansion device. FIG. 3A and 3B are
transverse cross-sectional views of the expansion device, in which
FIG. 3A is a cross-sectional view of the expansion device taken on
line A-A of FIG. 2A, and FIG. 3B is a cross-sectional view of the
expansion device taken on line B-B of FIG. 2A.
[0055] Referring first to FIG. 1, the expansion device 1 is
disposed in the piping 50 forming a flow passage of refrigerant
circulating through a refrigeration cycle for an automotive air
conditioner, and formed by a differential pressure valve that
controls a differential pressure thereacross such that a
predetermined supercooling degree of the refrigerant is obtained.
It should be noted that flows of refrigerant are indicated by
arrows in FIG. 1 (the same applies in the following). In the
following description of the configuration shown in FIG. 1, the
right side and the left side, as viewed in the figure, are
sometimes referred to as the "upstream side" and the "downstream
side", respectively, with reference to the direction of flow of
refrigerant.
[0056] As shown in FIG. 2A, the expansion device 1 comprises a
cylinder 10 in the form of a hollow cylinder, and a valve element
20 in the form of a hollow cylinder inserted in the cylinder
10.
[0057] The cylinder 10 has a hollow cylindrical body 11, and
includes a valve seat 12 formed by a stepped portion formed at an
upstream location inside the body 11. In other words, a refrigerant
passage that allows passage of refrigerant is formed through the
cylinder 10, by a small pipe portion 13 that is formed toward the
upstream end, and a large pipe portion 14 that is formed on the
downstream side of the small pipe portion 13 in a manner
communicating therewith such that the large pipe portion 14 has a
larger passage cross-section than that of the small pipe portion
13.
[0058] At an upstream end of the cylinder 10, a strainer 15 is
fitted on an inlet of the small pipe portion 13 through which
high-pressure refrigerant is introduced, and a flange 16 is formed
which extends radially outward for securing the expansion device 1
to the piping 50. Further, the cylinder 10 has a fitting groove 10a
circumferentially formed in an outer periphery of the small pipe
portion 13 for having an O ring fitted therein for preservation of
hermeticity when the expansion device 1 is fixed to the piping 50.
Furthermore, a stopper 17 in the form of a bottomed hollow cylinder
is fixed in the cylinder 10 at a location in the vicinity of a
downstream end of the large pipe portion 14, with a spring 18
interposed between the stopper 17 and the valve element 20.
[0059] On the other hand, the valve element 20 has a stepped hollow
cylindrical body 21 inserted into the cylinder 10. The body 21 has
a valve portion 22 formed at an upstream end thereof such that the
valve portion 22 can be moved to and away from the valve seat 12, a
guided portion 23 formed at a location downstream of the valve
portion 22, for being guided along an inner peripheral surface of
the cylinder 10, and further a refrigerant passage 24 formed in a
manner axially extending through the body 21 for passage of
refrigerant therethrough.
[0060] The valve portion 22 is formed to have a tapered shape such
that an outer diameter thereof is progressively reduced toward the
upstream end of the body 21. When the valve portion 22 is seated on
the valve seat 12, the foremost end of the valve portion 22 is
inserted into the small pipe portion 13 by a predetermined
amount.
[0061] The guided portion 23 is formed by three protrusions 23a
extending from the body 21 toward the inner surface of the cylinder
10 at equal intervals (of 120 degrees), and other refrigerant
passages than the refrigerant passage 24 are formed between the
protrusions 23a, to allow passage of refrigerant. The foremost ends
of the protrusions 23a slide along the inner surface of the
cylinder 10, whereby the valve element 20 can be moved to and away
from the valve seat 12.
[0062] The refrigerant passage 24 has a stepped portion 25 where
the refrigerant passage 24 expanded from the upstream side toward
the downstream side, and from the expanded side of the stepped
portion 25, an inner shaft member 30 in the form of a hollow
cylinder is inserted which functions as a restriction mechanism.
That is, the flow passage through the inner shaft member 30
provides a restriction that has a cross-section smaller than the
cross-section of the refrigerant passage 24, and decompresses
refrigerant flowing through the refrigerant passage 24, such that
the refrigerant pressure is reduced across the restriction.
Although the inner shaft member 30 is supported by the valve
element 20, it is not fixed to any part of an internal structure
within the cylinder 10, and part of the inner shaft member 30
protrudes downward from the valve element 20, with the downstream
end face thereof being in abutment with the bottom of the stopper
17 and held thereat, whereby the downstream movement of the inner
shaft member 30 is limited. That is, although the inner shaft
member 30 has the radial movement and the axial movement thereof
limited by the valve element 20 and the stopper 17, respectively,
it is not fixed to any part of the internal structure, and
therefore it brings about no inconveniences such as limiting of the
movement of the valve element 20.
[0063] At a location where the stopper 17 is in contact with the
inner shaft member 30, there is formed a through hole 17a having a
larger passage cross-section than that of the passage or
restriction through the inner shaft member 30, thereby preventing
the flow of refrigerant from being blocked even when the inner
shaft member 30 is slightly radially displaced. Further, as shown
in FIG. 3B, around the through hole 17a, there are provided four
slots 17b (second through holes) that are connected to the
aforementioned other refrigerant passages than the refrigerant
passage 24. The sum of flow passage areas of these four slots 17b
is sufficiently larger than the flow passage area of a gap formed
between the valve portion 22 and the valve seat 12 when the valve
element 20 is opened, which suppresses pressure loss of the
refrigerant which can occur in the slots 17b.
[0064] The spring 18 is formed by a compression coil spring having
a predetermined elastic coefficient, and has an upstream portion
thereof inserted around the body 21 of the valve element 20. The
spring 18 has one end thereof in abutment with the bottom of the
stopper 17 at a location in the vicinity of the peripheral edge
thereof, and the other end thereof in abutment with a downstream
end face of the guided portion 23 of the valve element 20, thereby
urging the valve element 20 toward the valve seat 12 (in the
valve-closing direction) with a predetermined elastic force
thereof.
[0065] Further, the stopper 17 is equipped with an adjusting
mechanism, that is, the stopper 17 has an outer periphery formed
with an external thread, and a downstream end of the cylinder 10 is
formed with an internal thread mating with the external thread. By
adjusting the amount of screwing of the stopper 17 into the
cylinder 10, the position of the stopper 17 is adjusted, whereby
the elastic force of the spring 18 can be adjusted.
[0066] The expansion device 1 configured as described above is
fixed to the piping 50 as shown in FIG. 1. More specifically, the
piping 50 has a joint structure which connects between a
downstream-side pipe 51 and an upstream-side pipe 52, at an
location where the expansion device 1 is installed therein. The
downstream-side pipe 51 has a stepped portion 53 formed by
expanding an upstream end thereof, and the downstream end of the
upstream-side pipe 52 is inserted into the expanded portion of the
downstream-side pipe 51 whereby the two pipes are joined. The
hermeticity between these downstream-side and upstream-side pipes
51 and 52 is preserved by an O ring 54 fitted in a groove formed in
the downstream end of the upstream-side pipe 52.
[0067] The expansion device 1 has its flange 16 sandwiched between
the stepped portion 53 of the downstream-side pipe 51 and the
downstream end face of the upstream-side pipe 52, whereby it is
fixed within the piping 50. The hermeticity between the expansion
device 1 and the piping 50 is preserved by the O ring 10b provided
within the fitting groove 10a in the cylinder 10. The expansion
device 1 is not equipped with a casing or the like for
accommodating the cylinder 10, but has its cylinder 10 directly
fixed to the piping 50.
[0068] Next, the pressure-cancelling structure of the expansion
device 1 will be described.
[0069] As shown in FIG. 2A, in the expansion device 1, the valve
portion 22 of the valve element 20 is formed with a valve-opening
pressure-receiving surface 26 facing upstream for receiving
refrigerant pressure which acts on the valve element in the
valve-opening direction, as is conventional with the valve element.
In addition, the stepped portion 25 of the valve element 20 is
formed with a valve-closing pressure-receiving surface 27 for
receiving refrigerant pressure which acts on the valve element 20
in the valve-closing direction. That is, refrigerant introduced
into the inner space between the stepped portion 25 of the valve
element 20 and the inner shaft member 30 applies pressure to the
valve element 20 in the valve-closing direction (rightward as
viewed in FIG. 2A), to thereby cancel part of the refrigerant
pressure acting on the valve element 20 in the valve-opening
direction. In the present embodiment, the passage cross-section of
the small pipe portion 13 is formed to be larger than the
cross-section of the expanded pipe side of the stepped portion 25,
so that when the valve element 20 is seated on the valve seat 12,
the valve-closing pressure-receiving surface 27 has a smaller
pressure-receiving area than that of the valve-opening
pressure-receiving surface 26. Therefore, the resultant of the
pressure received at the valve-closing pressure-receiving surface
27 and the elastic force of the spring 18 acts against the
refrigerant pressure received at the valve-opening
pressure-receiving surface 26.
[0070] Next, the relief mechanism of the expansion device 1 will be
described.
[0071] As shown in FIGS. 2A and 2B, in the expansion device 1, when
the differential pressure across the expansion device 1 has become
equal to or higher than a predetermined value to cause the valve
portion 22 to be moved away the valve seat 12, most of refrigerant
flowing in from the upstream side is allowed to escape through the
gap between the valve portion 22 and the valve seat 12, and flow
downstream through the aforementioned other refrigerant passages
formed between the valve element 20 and the cylinder 10 and the
slots 17b of the stopper 17. This prevents an abnormal rise in the
refrigerant pressure inside the expansion device 1.
[0072] FIG. 4 is an explanatory view showing the relationship
between the differential pressure across the expansion device 1 and
the opening area of the refrigerant passage(s) thereof.
[0073] As shown in FIG. 4, so long as the valve element 20 is
seated on the valve seat 12 (state shown in FIG. 2A), even if the
differential pressure rises, the opening area is held at the
cross-sectional area of the refrigerant passage 24. Then, when the
differential pressure becomes higher than the predetermined value,
the valve element 20 is moved away from the valve seat 12 to allow
the refrigerant to escape into the other refrigerant passages
outside the valve element 20 to relieve the refrigerant pressure.
Thus, the opening area is instantly increased (state shown in FIG.
2B).
[0074] As described above, in the expansion device 1 according to
the present embodiment, the pressure-cancelling structure cancels
part of the refrigerant pressure. That is, the elastic force
required of the spring 18 can be reduced by the amount of pressure
received at the valve-closing pressure-receiving surface 27. As a
result, a small-sized spring can be employed for the spring 18,
which enables the entire expansion device 1 to be made compact in
size.
[0075] Further, when the differential pressure across the expansion
device 1 has become equal to or higher than the predetermined
value, the refrigerant flowing in from the upstream side can be
caused to escape into the other refrigerant passages than the
refrigerant passage 24 of the valve element 20, which makes it
possible to prevent an abnormal rise in the refrigerant pressure
inside the expansion device 1, to thereby prevent breakage or the
like of the internal components.
Second Embodiment
[0076] Next, a second embodiment of the present invention will be
described. FIGS. 5A to 5C are cross-sectional views of an expansion
device according to the present embodiment, in which FIGS. 5A and
5B are longitudinal cross-sectional views of the expansion device,
while FIG. 5C is a cross-sectional view taken on line C-C of FIG.
5A. It should be noted that components similar to those of the
first embodiment will be designated by identical reference
numerals, and description thereof is omitted.
[0077] As shown in FIG. 5A, the expansion device 201 comprises a
cylinder in the form of a hollow cylinder 210, and a valve element
in the form of a hollow cylinder 220 inserted into the cylinder
210.
[0078] The cylinder 210 comprises a valve seat portion 213 as a
separate member in the form of a hollow cylinder fixed to the
inside of the cylinder 210, a large pipe portion 214 having a
larger passage cross-section than that of the valve seat portion
213 and communicating with the downstream side of the valve seat
portion 213, and a guide pipe portion 215 having a smaller passage
cross-section than that of the large pipe portion 214 and
communicating with the downstream side of the large pipe portion
214.
[0079] The valve seat portion 213 has one end opening in the
upstream direction, and is formed with a valve seat 212 at the
other end thereof, for having the valve element 220 seated
thereon.
[0080] When the expansion device 201 is disposed within the piping
50, the large pipe portion 214 and the guide pipe portion 215
define a refrigerant passage that allows passage of refrigerant,
between these portions 214 and 215 and the piping 50.
[0081] As shown in FIG. 5C, the large pipe portion 214 has a valve
portion 222, referred to hereinafter, of the valve element 220
inserted therein, and a pair of communication holes 214a formed
through upper and lower portions of the side wall thereof, as
viewed in the figure, for communication of the inside thereof with
the above-mentioned refrigerant passage, and defines a space
portion 241 communicating with the communication holes 214a,
between itself and the valve element 220.
[0082] The guide pipe portion 215 has a guided portion 233,
referred to hereinafter, of the valve element 220 inserted therein
such that the guided portion 233 is slidably held thereby, and an
orifice hole 215a (restriction mechanism), as a restriction, formed
through a central portion of the downstream end thereof.
[0083] On the other hand, the valve element 220 has a body 221 in
the form of a hollow cylinder inserted in the cylinder 201. The
body 221 has the valve portion 222 formed at an upstream end
thereof, for being removably seated on the valve seat 212, and the
guided portion 223 formed on the downstream side of the valve
portion 222, for being guided along the inner peripheral surface of
the guide pipe portion 215. Further, a refrigerant passage 224
axially extends through the inside of the body 221 to allow passage
of refrigerant.
[0084] The valve portion 222 is formed to have a tapered shape such
that an outer diameter thereof is progressively reduced toward the
upstream end of the body 221. When the valve portion 222 is seated
on the valve seat 212, the foremost end of the valve portion 222 is
inserted into the small pipe portion 213 by a predetermined
amount.
[0085] The guided portion 223 is formed by a reduced-diameter
portion of the body 221, and inserted into the guide pipe portion
215. The guided portion 223 is slid along the inner surface of the
guide pipe portion 215, whereby the valve element 20 can be driven
forward and backward with respect to the valve seat 12. A spring
218 is interposed between the downstream end face of the guided
portion 223 and the downstream end face of the guide pipe portion
215, for urging the valve element 220 toward the valve seat 212 (in
the valve-closing direction) with a predetermined elastic force
thereof.
[0086] The refrigerant passage 224 extends with the same
cross-section from the upstream side to the downstream side, and
allows passage of high-pressure refrigerant flowing in via the
strainer 15. The refrigerant having passed therethrough is
decompressed by passing through the orifice hole 215a.
[0087] The valve seat portion 213 is equipped with an adjusting
mechanism, that is, the valve seat portion 213 has an outer
periphery formed with an external thread, and an upstream end of
the cylinder 210 is formed with an internal thread mating with the
external thread. By adjusting the amount of screwing of the valve
seat portion 213 into the cylinder 210, the position of the valve
seat portion 213 is adjusted, whereby the elastic force of the
spring 218 can be adjusted via the valve element 220.
[0088] Next, the pressure-cancelling structure of the expansion
device 201 will be described.
[0089] As shown in FIG. 5A, in the expansion device 201, the valve
portion 222 of the valve element 220 is formed with a valve-opening
pressure-receiving surface 226 facing upstream for receiving
refrigerant pressure which acts on the valve element 220 in the
valve-opening direction. In addition, a downstream end face of the
guided portion 223 of the valve element 20 is formed with a
valve-closing pressure-receiving surface 227 for receiving
refrigerant pressure which acts on the valve element 20 in the
valve-closing direction. That is, refrigerant introduced into the
guide pipe portion 215 via the guided portion 223 of the valve
element 220 applies pressure to the valve element 220 in the
valve-closing direction (rightward as viewed in FIG. 5A), to
thereby cancel part of the refrigerant pressure acting on the valve
element 220 in the valve-opening direction. In the present
embodiment, the passage cross-section of the valve seat portion 213
is formed to be larger than that of the guide pipe portion 215, so
that when the valve element 220 is seated on the valve seat 212,
the valve-closing pressure-receiving surface 227 has a smaller
pressure-receiving area than that of the valve-opening
pressure-receiving surface 226. Therefore, the resultant of the
pressure received at the valve-closing pressure-receiving surface
227 and the elastic force of the spring 218 acts against the
refrigerant pressure received at the valve-opening
pressure-receiving surface 226.
[0090] Next, the relief mechanism of the expansion device 201 will
be described.
[0091] As shown in FIGS. 5A and 5B, in the expansion device 201,
when the differential pressure across the expansion device 201 has
become equal to or higher than a predetermined value to cause the
valve portion 222 to be moved away the valve seat 212, most of
refrigerant flowing in from the upstream side is allowed to escape
through a gap between the valve portion 222 and the valve seat 212,
and introduced into the refrigerant passage formed between the
piping 50 and the cylinder 210 via the space portion 241 and the
communication holes 214a, to flow downstream. This prevents an
abnormal rise in the refrigerant pressure inside the expansion
device 201 is prevented.
[0092] As described above, in the expansion device 201 according to
the present embodiment, since the pressure-cancelling structure
cancels part of the refrigerant pressure, a small-sized spring can
be employed for the spring 218. As a result, it is possible to make
the entire expansion device 201 compact in size.
[0093] Further, when the differential pressure across the expansion
device 201 has become equal to or higher than the predetermined
value, the refrigerant flowing in from the upstream side can be
caused to escape into a flow passage other than the refrigerant
passage 224 of the valve element 220, which makes it possible to
prevent an abnormal rise in the refrigerant pressure inside the
expansion device 201, to thereby prevent breakage or the like of
the internal components.
Third Embodiment
[0094] Next, a third embodiment of the present invention will be
described. FIGS. 6A to 6C are cross-sectional views of an expansion
device according to the present embodiment, in which FIGS. 6A and
6B are longitudinal cross-sectional views of the expansion device,
while FIG. 6C is a cross-sectional view taken on line D-D of FIG.
6A. It should be noted that components similar to those of the
first embodiment will be designated by identical reference
numerals, and description thereof is omitted.
[0095] As shown in FIG. 6A, the expansion device 301 comprises a
cylinder in the form of a hollow cylinder 310, and a valve element
320 in the form of a hollow cylinder inserted in the cylinder
310.
[0096] The cylinder 310 includes a small pipe portion 313 slidably
supporting a guided portion, referred to hereinafter, of the valve
element 320, and a large pipe portion 314 that has a larger passage
cross-section than that of the small pipe portion 313, and has a
valve portion, referred to hereinafter, of the valve element 320
inserted therein. A valve seat 312 is formed by a stepped portion
formed on a communicating portion between the small pipe portion
313 and the large pipe portion 314.
[0097] The small pipe portion 313 is, as shown in FIG. 6C, has a
pair of introducing holes 313a formed through upper and lower
portions of the side wall, as viewed in the figure, for having
refrigerant introduced therein, with a closed upstream end of the
small pipe portion 313 and a downstream end of the same
communicating with the large pipe portion 314. The small pipe
portion 313 is expanded by a predetermined amount toward the large
pipe portion 314 to form an expanded pipe portion 313b in the
vicinity of the valve seat 312. A strainer 315 is fitted on the
small pipe portion 313 such that it covers the small pipe portion
313 from outside.
[0098] A stopper 317 in the form of a hollow cylinder is fixed to
the large pipe portion 314 at a location in the vicinity of the
downstream end thereof, and a spring 318 is inserted between the
stopper 317 and the valve element 320, for urging the valve element
320 in the direction of the valve seat 312.
[0099] On the other hand, the valve element 320 has a body 321 in
the form of a hollow cylinder. The body 321 has the guided portion
322 formed at an upstream end thereof, for sliding along the inner
surface of the small pipe portion 313, and a valve portion 323
formed at a downstream end thereof, for being removably seated on
the valve seat 312. Further, a refrigerant passage 324 axially
extends through the inside of the body 321 to allow passage of
refrigerant. Further, a space portion 341 communicating with the
introducing holes 313a is defined between the valve element 320 and
the small pipe portion 313, at the location of a pipe portion 325
between the guided portion 322 of the valve portion 323 of the
valve element 320.
[0100] The pipe portion 325 has a side wall formed with an orifice
hole 331 that communicates between the space portion 341 and the
refrigerant passage 324, and functions a restriction mechanism, and
when the valve element 320 is seated, the refrigerant flowing in
from the piping 50 is introduced via the introducing holes 313a and
the orifice hole 331 into the refrigerant passage 324. At the
downstream end of the refrigerant passage 324, there is formed an
expanded pipe portion 332 which is expanded by a predetermined
amount for suppressing pressure loss of the refrigerant flowing
through the refrigerant passage 324.
[0101] The stopper 317 is equipped with an adjusting mechanism,
that is, the stopper 317 has an outer periphery formed with an
external thread, and a downstream end of the cylinder 310 is formed
with an internal thread mating with the external thread. By
adjusting the amount of screwing of the stopper 317 into the
cylinder 310, the position of the stopper 317 is adjusted, whereby
the elastic force of the spring 318 can be adjusted.
[0102] Next, the pressure-cancelling structure of the expansion
device 301 will be described.
[0103] As shown in FIG. 6A, in the expansion device 301, the valve
portion 323 of the valve element 320 is formed with a valve-opening
pressure-receiving surface 326 facing upstream for receiving
refrigerant pressure which acts on the valve element 320 in a
valve-opening direction. In addition, the downstream end of the
guided portion 322 of the valve element 320 is formed with a
valve-closing pressure-receiving surface 327 for receiving
refrigerant pressure which acts on the valve element 320 in the
valve-closing direction. That is, refrigerant introduced into the
space portion 341 through the introducing hole 313a applies
pressure to the valve-opening pressure-receiving surface 327 of the
valve element 320 in the valve-closing direction (rightward as
viewed in FIG. 6A), and to the valve-opening pressure-receiving
surface 326 of the same in the valve-opening direction (leftward as
viewed in FIG. 6A) to thereby cancel part of the refrigerant
pressure acting on the valve element 320 in the valve-opening
direction. In the present embodiment, since the expanded pipe
portion 313b is provided, so that when the valve element 320 is
seated on the valve seat 312, the valve-closing pressure-receiving
surface 327 has a smaller pressure-receiving area than that of the
valve-opening pressure-receiving surface 326. Therefore, the
resultant of the pressure received at the valve-closing
pressure-receiving surface 327 and the elastic force of the spring
318 acts against the refrigerant pressure received at the
valve-opening pressure-receiving surface 326.
[0104] Next, the relief mechanism of the expansion device 301 will
be described.
[0105] As shown in FIGS. 6A and 6B, in the expansion device 301,
when the differential pressure across the expansion device 301 has
become equal to or higher than a predetermined value to cause the
valve portion 323 to be moved away the valve seat 312, most of
refrigerant flowing in from the upstream side is allowed to escape
through a refrigerant passage formed by a gap between the valve
portion 323 and the valve seat 312, to flow downstream by being
guided through the large pipe portion 314. This prevents an
abnormal rise in the refrigerant pressure inside the expansion
device 301.
[0106] As described above, in the expansion device 301 according to
the present embodiment, since the pressure-cancelling structure
cancels part of the refrigerant pressure, a small-sized spring can
be employed for the spring 318. As a result, it is possible to make
the entire expansion device 301 compact in size.
[0107] Further, when the differential pressure across the expansion
device 301 has become equal to or higher than the predetermined
value, the refrigerant flowing in from the upstream side can be
caused to escape into a flow passage other than the refrigerant
passage 324 of the valve element 320, which makes it possible to
prevent an abnormal rise in the refrigerant pressure inside the
expansion device 301, to thereby prevent breakage or the like of
the internal components.
Fourth Embodiment
[0108] Next, a fourth embodiment of the present invention will be
described. FIG. 7A to 7C are longitudinal cross-sectional views of
an expansion device according to the present embodiment, and FIG. 8
is a cross-sectional view taken on line E-E of FIG. 7A. It should
be noted that since most of the components of the expansion device
according to the present embodiment are similar to those of the
first embodiment, components similar to those of the first
embodiment will be designated by identical reference numerals, and
description thereof is omitted.
[0109] As shown in FIG. 7A, the expansion device 401 comprises a
cylinder 10 in the form of a hollow cylinder, and a valve element
420 in the form of a hollow cylinder inserted in the cylinder
10.
[0110] The valve element 420 has a body 421 in the form of a
stepped hollow cylinder inserted in the cylinder 10, and a valve
portion 422 is formed at an upstream end of the body 421, for being
removably seated on the valve seat 12, with a refrigerant passage
424 axially extending through the inside of the body 421 to allow
passage of refrigerant.
[0111] The valve portion 422 has a tapered end the outer diameter
of which decreases toward the upstream end of the body 421, and an
extended portion that is extended from the tapered end by a
predetermined amount, and is configured to be fitted in the small
pipe portion 13 by the predetermined amount when the valve element
420 is seated. Further, as shown in FIG. 8, a slit 431 is formed
through a side wall of an upstream end of the valve portion 422,
which opens toward the small pipe portion 13.
[0112] Next, the pressure-cancelling structure of the expansion
device 401 is distinguished from that of the first embodiment in
that a valve-opening pressure-receiving surface 426 formed on the
valve portion 422 of the valve element 420 in a manner facing
upstream, for receiving refrigerant pressure acting on the valve
element 420 in the valve-opening direction has a shape slightly
different from that of the valve-opening pressure-receiving surface
26 of the first embodiment, but is the same in that the resultant
of the pressure received at the valve-closing pressure-receiving
surface 27 and the elastic force of the spring 18 acts against the
refrigerant pressure received at the valve-opening pressure
receiving surface 426.
[0113] Next, the relief mechanism of the expansion device 401 will
be described.
[0114] As shown in FIGS. 7A to 7C, in the expansion device 401,
when the differential pressure across the expansion device 401 has
become equal to or higher than a predetermined value to cause the
valve portion 422 to start to be moved away the valve seat 12, part
of refrigerant flowing in from the upstream side is allowed to flow
downstream through a refrigerant passage formed between the valve
element 420 and the cylinder 10 via the slit 431.
[0115] Then, as the differential pressure further rises, the
opening communicating between the small pipe portion 13 and the
large pipe portion 14 is progressively increased due to the slit
431, and when the upstream end of the valve portion 420 is removed
from the small pipe portion 13, the opening is sharply increased,
whereby most of the refrigerant flowing in from the upstream side
is allowed to escape into a flow passage other than the refrigerant
passage 424 in the valve element 420, to allow the same to flow to
the downstream side.
[0116] FIG. 9 is an explanatory view showing the relationship
between the differential pressure across the expansion device 401
and the opening area of the refrigerant passage(s) thereof.
[0117] As shown in FIG. 9, so long as the valve element 420 is
seated on the valve seat 12 (state shown in FIG. 7A), even if the
differential pressure rises, the opening area is held at the
cross-sectional area of the restriction of the inner shaft member
30. Then, when the differential pressure becomes higher than a
predetermined value, the refrigerant is allowed to escape through
the slit 431, which allows the opening area to be gently increased
in response to changes in the differential pressure across the
expansion device (state shown in FIG. 7B). Then, when the
differential pressure further rises, the upstream end of the valve
element 420 is removed from the small pipe portion 13, which
instantly increases the opening area in response to a change in the
differential pressure (state shown in FIG. 7C).
[0118] As described above, in the expansion device 401 according to
the present embodiment, the refrigerant flowing in from the
upstream side is allowed to escape in a stepwise manner. As a
result, it is possible to prevent an abnormal rise in the
refrigerant pressure inside the expansion device 401, to thereby
prevent breakage or the like of the internal components. Further,
by the stepwise relief, of the refrigerant pressure, the flow
characteristics representative of the relationship between the
differential pressure across the expansion device 401 and the
opening area of the refrigerant passage thereof can be set
differently from those of the first embodiment.
Fifth Embodiment
[0119] Next, a fifth embodiment of the present invention will be
described. The present embodiment is an application of the
configuration of the fourth embodiment to the configuration of the
second embodiment. FIGS. 10A to 10C are longitudinal
cross-sectional views of an expansion device according to the
present embodiment. It should be noted that most of the
configuration of the expansion device according to the present
embodiment is similar to that of the second embodiment, and
therefore description thereof is omitted by designating the similar
components with identical reference numerals.
[0120] As shown in FIG. 10A, the expansion device 501 comprises a
cylinder in the form of a hollow cylinder 210, and a valve element
520 in the form of a hollow cylinder inserted in the cylinder
210.
[0121] A valve portion 522 of the valve element 520 has a tapered
end extended upstream by a predetermined amount such that the outer
diameter thereof decreases toward the upstream end of a body 521,
and is configured to be fitted in the valve seat portion 213 by the
predetermined amount when the valve element 520 is seated. Further,
a slit 531 is formed through a side wall of an upstream end of the
valve portion 522, which opens toward the valve seat portion 213.
It should be noted that the slit 531 shown in FIGS. 10A to 10C
operate similarly to the slit 431 of the fourth embodiment, and
therefore description thereof is omitted.
[0122] Thus, in the expansion device 501 according to the present
embodiment as well, with the provision of the slit 531, the
refrigerant flowing in from the upstream side is allowed to escape
in a stepwise manner. As a result, the flow characteristics
representative of relationship between the differential pressure
across the expansion device 501 and the opening area of the
refrigerant passage can be configured differently from those of the
first embodiment.
Sixth Embodiment
[0123] Next, a sixth embodiment of the present invention will be
described. In the present embodiment, the relief mechanism is
provided in two stages. FIGS. 11A to 11C are longitudinal
cross-sectional views of an expansion device according to the
present embodiment. In FIGS. 12A to 12E, FIG. 12A is a longitudinal
cross-sectional view of an inner cylinder, FIG. 12B a plan view of
the same, FIG. 12C a cross-sectional view taken on line F-F of A,
FIG. 12D a left side view, and further, FIG. 12E a right side view.
It should be noted that components similar to those of the first
embodiment will be designated by identical reference numerals, and
description thereof is omitted.
[0124] As shown in FIG. 11A, the expansion device 601 comprises a
cylinder 602 in the form of a hollow cylinder formed to be axially
longer than the cylinder 10 of the first embodiment, a first relief
mechanism 610 inserted in a upstream part of the cylinder 602, and
a second relief mechanism 620 inserted in a downstream part of the
same.
[0125] It should be noted that the first relief mechanism 610 is
formed by a first valve element 20 which is removably seated on a
first valve seat 12 formed by a stepped portion provided inside the
cylinder 602, and hence is configured similarly to the relief
mechanism of the first embodiment. Further, the first valve element
20 also has the pressure-cancelling structure as described in the
first embodiment, and hence description of the relief mechanism and
the pressure-cancelling structure will be omitted.
[0126] On the other hand, the second relief mechanism 620 comprises
an inner cylinder 640 formed on the downstream side of the first
relief mechanism 610 in a manner continuous therewith, and a second
valve element 650 disposed within the inner cylinder 640.
[0127] The inner cylinder 640 has a body in the form of a hollow
cylinder, as shown in FIGS. 12A to 12E, which has a stepped portion
641 with a reduced inner diameter formed at an upstream end
thereof, and is configured such that the upstream end of the body
can hold the downstream end of the inner shaft member 30. Further,
a communication hole 644 is formed through the stepped portion 641,
which communicates with the restriction of the inner shaft member
30.
[0128] Further, the upstream end of the inner cylinder 640 has a
side wall formed with a pair of slits 642 which opens in the
upstream direction, and the downstream end of the same with a
slightly-increased outer diameter has an adjusting portion 643
constituting an adjusting mechanism, referred to hereinafter. The
slits 642 communicate between a refrigerant passage formed between
the inner cylinder 640 and the cylinder 602 and the inside of the
inner cylinder 640, to allow passage of the refrigerant flowing
through the refrigerant passage to thereby allow the refrigerant to
flow downstream of the second valve element 650 of the inner
cylinder 640.
[0129] Referring again to FIGS. 11A to 11C, the upstream end face
of the inner cylinder 640 has a spring 18 in contact therewith
which is interposed between the upstream end face of the inner
cylinder 640 and the first valve element 20. That is, the adjusting
portion 643 has an outer periphery formed with an external thread,
and a downstream end of the cylinder 602 is formed with an internal
thread mating with the external thread. By adjusting the amount of
screwing of the inner cylinder 640 into the cylinder 602, the
position of the inner cylinder 640 is adjusted, whereby the elastic
force of the spring 18 can be adjusted. Further, the downstream end
of the inner cylinder 640 has a stopper 617 in the form of a hollow
cylinder fixed thereto, and a spring 618 (second elastic member)
having a smaller elastic constant than that of the spring 18 is
interposed between the stopper 617 and the second valve element
20.
[0130] On the other hand, the second valve element 650 has a body
in the form of a hollow cylinder inserted in the inner cylinder
640, and includes a valve portion 651 and a guided portion 653
forming parts of the body. A second refrigerant passage 654 having
a smaller cross-section than the passage cross-section of the
restriction of the inner shaft member 30 extends trough the inside
of the body.
[0131] The guided portion 653 has an outer diameter substantially
equal to an inner diameter of the communication hole 644, and an
upstream end of the guided portion 653 forms the valve portion 651.
Further, on the downstream side of the guided portion 653, a flange
652 is formed which extends radially outward, and one end of the
spring 618 is in abutment with the flange 652. A portion of the
second valve element 650 on a further downstream side of the flange
652 has a tapered shape the outer diameter of which decreases
downstream. The second valve element 650 moves to and away from the
stepped portion 641 while being guided along the communication hole
644. The valve portion 651 is removably seated on the downstream
end face of the inner shaft member 30 as a valve seat (second valve
seat).
[0132] Further, the stopper 617 is equipped with an adjusting
mechanism, that is, the stopper 617 has an outer periphery formed
with an external thread, and a downstream end of the inner cylinder
640 is formed with an internal thread mating with the external
thread. By adjusting the amount of screwing of the stopper 617 into
the inner cylinder 640, the position of inner cylinder 640 is
adjusted, whereby the elastic force of the spring 618 can be
adjusted.
[0133] Next, the relief mechanism of the expansion device 601 will
be described.
[0134] As shown in FIGS. 11A to 11C, in the expansion device 601,
when the differential pressure across the expansion device 601 has
become equal to or higher than a first predetermined value, the
first relief mechanism 610 operates, and when the differential
pressure has become equal to or higher than a second predetermined
value, the second relief valve 620 operates. In the present
embodiment, the first predetermined value is configured to be
larger than the second predetermined value, and the amount of
refrigerant allowed to escape by the first relief mechanism 610 is
set to be larger than the amount of refrigerant allowed to escape
by the second relief mechanism 620. Further, the second relief
mechanism 620 on the downstream side is first operated to allow
refrigerant to escape at a small flow rate, and thereafter, the
first relief mechanism 610 on the upstream side is operated to
allow the refrigerant to escape at a large flow rate.
[0135] That is, when the differential pressure across the expansion
device 601 has become equal to or higher than the second
predetermined value, as shown in FIGS. 11A and 11B, the upstream
end face of the second valve element 650 of the second relief
mechanism 620 is moved away from the downstream end face of the
inner shaft member 30 to terminate the contact state therebetween,
whereby part of refrigerant flowing through the restriction of the
inner shaft member 30 into the communication hole 644 is allowed to
escape through a gap between the downstream end face of the inner
shaft member 30 and the upstream end face of the second valve
element 650. The refrigerant flows via the slit 642 and the
refrigerant passage between the inner cylinder 640 and the cylinder
602 (i.e. the other different passage than the second refrigerant
passage 654) to the downstream side of the second valve element 650
of the inner cylinder 640.
[0136] Then, when the differential pressure across the expansion
device 601 become equal to or higher than the first predetermined
value to cause the valve portion 22 of the first relief mechanism
610 to be moved away from the valve seat 12, most of the
refrigerant flowing in from the downstream side is allowed to
escape via the gap between the valve portion 22 and the valve seat
12, and flow downstream via the refrigerant passage formed between
the first valve element 20 and the cylinder 602, the refrigerant
passage between the inner cylinder 640 and the cylinder 602, and
the slit 642. This prevents an abnormal rise in the refrigerant
pressure inside the expansion device 601.
[0137] As described above, in the expansion device 601 according to
the present embodiment, the relief mechanism is provided in two
stages, i.e. as the first relief mechanism 610 and the second
relief mechanism 620, so that by shifting the timing of the relief
of the refrigerant pressure, the refrigerant pressure inside the
expansion device 601 can be reduced in two stages. Further, by
differentiating the amount of relief between the two mechanisms, it
is possible to carry out reduction control of the refrigerant
pressure in various manners. Therefore, it is possible to realize
delicate pressure reduction control such that the operations of the
internal components of the expansion device 601 are not adversely
affected, to thereby effectively prevent breakage or the like of
the internal components.
Seventh Embodiment
[0138] Next, a seventh embodiment of the present invention will be
described. In the present embodiment as well, the relief mechanism
is provided in two stages. FIG. 13A to 13C are longitudinal
cross-sectional views of an expansion device according to the
present embodiment. FIG. 14 is a cross-sectional view taken on line
G-G of FIG. 13A. It should be noted that components similar to
those of the first embodiment will be designated by identical
reference numerals, and description thereof is omitted.
[0139] As shown in FIG. 13A, the expansion device 701 comprises the
hollow cylinder 702 formed to be axially longer than the cylinder
10 of the first embodiment, a first relief mechanism 710 inserted
in a upstream part of the inside of the cylinder 702, and a second
relief mechanism 720 inserted in a downstream part of the same.
[0140] It should be noted that the first relief mechanism 710 is
formed by a first valve element 20 which is removably seated on a
first valve seat 12 formed by a stepped portion provided inside the
cylinder 702, and the second relief mechanism 720 is formed by a
second valve element 20 which is removably seated on a second valve
seat 752 formed by a downstream end of a stopper 750, referred to
hereinafter, disposed within the cylinder 702. Both of the
mechanisms are configured similarly to the relief mechanism of the
first embodiment. However, the passage cross-section of the inner
shaft member 730 of the second relief mechanism 720 is smaller than
that of the inner shaft member 30 of the first relief mechanism 710
by a predetermined amount. It should be noted that in FIGS. 13A to
13C, the valve-opening pressure-receiving surface and the
valve-closing pressure-receiving surface of the first valve element
20 on the upstream side form a first valve-opening
pressure-receiving surface and a first valve-closing
pressure-receiving surface, and the valve-opening
pressure-receiving surface and the valve-closing pressure-receiving
surface of the second valve element 20 on the downstream side form
a second valve-opening pressure-receiving surface and a second
valve-closing pressure-receiving surface.
[0141] Further, the first valve element 20 and the second valve
element 20 each have the pressure-cancelling structure described in
the first embodiment, and hence description of the mechanism and
the structure will be omitted.
[0142] Between the first relief mechanism 710 and the second relief
mechanism 720, the stopper 750 in the form of a bottomed hollow
cylinder is interposed. At a location where the stopper 750 is in
contact with the inner shaft member 30, there is formed a through
hole 751 having a larger passage cross-section than that of the
inner shaft member 30, thereby preventing the flow of refrigerant
from being blocked even when the inner shaft member 30 is slightly
radially displaced. Further, as shown in FIG. 14, part of the outer
periphery of the stopper 750 is formed as a cutout portion 753
which is cut out parallel to the axis, thereby forming a
refrigerant passage between the cutout 753 and the cylinder 702,
which communicates between the upstream side and the downstream
side of the stopper 750.
[0143] Further, the stopper 750 is equipped with an adjusting
mechanism, that is, the stopper 750 has an outer periphery formed
with an external thread, and an inner wall of the cylinder 702 is
formed with an internal thread mating with the external thread. By
adjusting the amount of screwing of the stopper 750 into the
cylinder 702, the position of the stopper 750 is adjusted, whereby
the elastic force of the spring 18 can be adjusted.
[0144] Next, the relief mechanism of the expansion device 701 will
be described.
[0145] As shown in FIGS. 13A to 13C, in the expansion device 701,
the spring constant of the spring 18 as a component of the first
relief mechanism 710 and the spring constant of the spring 718 as a
component of the second relief mechanism 720 are made different
from each other, such that when the differential pressure across
the expansion device 701 has become equal to or higher than a first
predetermined value, the first relief mechanism 710 operates, and
when the differential pressure has become equal to or higher than a
second predetermined value, the second relief valve 720 operates.
In the present embodiment, the first predetermined value is
configured to be larger than the second predetermined value.
Further, the second relief mechanism 720 on the downstream side is
first operated to allow refrigerant to escape at a small flow rate,
and thereafter, the first relief mechanism 710 on the upstream side
is operated to allow the refrigerant to escape at a large flow
rate.
[0146] That is, when the differential pressure across the expansion
device 701 has become equal to or higher than the second
predetermined value, as shown in FIGS. 13A and 13B, the valve
portion 22 of the second relief mechanism 720 is moved away from
the second valve seat 752, whereby part of the refrigerant flowing
in from the upstream side via the inner shaft member 30 and the
stopper 750 is allowed to escape through a gap between the valve
portion 22 and the valve seat 752, and flow downstream via the
refrigerant passage formed between the second valve element 20 and
the cylinder 702.
[0147] Then, further when the differential pressure across the
expansion device 701 become equal to or higher than the first
predetermined value to cause the valve portion 22 of the first
relief mechanism 710 to be moved away from the valve seat 12, most
of the refrigerant flowing in from the upstream side is allowed to
escape via the gap between the valve portion 22 and the valve seat
12, and flow downstream via the refrigerant passage formed between
the first valve element 20 and the cylinder 702, the refrigerant
passage between the cutout portion 753 and cylinder 702, and the
refrigerant passage between the second valve element 20 and the
cylinder 702. This prevents an abnormal rise in the refrigerant
pressure inside the expansion device 701.
[0148] As described above, in the expansion device 701 according to
the present embodiment, the relief mechanism is provided in two
stages. Therefore, similarly to the sixth embodiment, it is
possible to realize delicate pressure reduction control such that
the operations of the internal components of the expansion device
701 are not adversely affected, to thereby effectively prevent
breakage or the like of the internal components.
Eighth Embodiment
[0149] Next, an eighth embodiment of the present invention will be
described. FIGS. 15A to 15C are longitudinal cross-sectional views
of an expansion device according to the present embodiment. It
should be noted that since most of the components of the expansion
device according to the present embodiment are similar to those of
the first embodiment, components similar to those of the first
embodiment will be designated by identical reference numerals, and
description thereof is omitted.
[0150] As shown in FIG. 15A, the expansion device 801 comprises a
cylinder 10 in the form of a hollow cylinder, and a valve element
820 in the form of a hollow cylinder inserted in the cylinder
10.
[0151] The valve element 820 has a body 821 in the form of a
stepped hollow cylinder inserted in the cylinder 10, and a valve
portion 822 is formed at an upstream end of the body 821, for being
removably seated on the valve seat 12, further with a refrigerant
passage 824 axially extending through the body 821 to allow passage
of refrigerant.
[0152] The valve element 822 is configured to have a tapered shape
the outer diameter of which decreases toward the upstream end of
the body 821, and when the valve element 820 is seated, the
upstream end thereof is inserted into the small pipe portion 13
such that a predetermined gap is formed between the upstream end
and the inner wall of the small pipe portion 13.
[0153] Next, the pressure-cancelling structure of the expansion
device 801 is distinguished from that of the first embodiment in
that a valve-opening pressure-receiving surface 826 formed on the
valve portion 822 of the valve element 820 in a manner facing
upstream, for receiving refrigerant pressure acting on the valve
element 820 in the valve-opening direction has a shape slightly
different from that of the valve-opening pressure-receiving surface
26 of the first embodiment, but is the same in that the resultant
of the pressure received at the valve-closing pressure-receiving
surface 27 and the elastic force of the spring 18 acts against the
refrigerant pressure received at the valve-opening pressure
receiving surface 826.
[0154] Next, the relief mechanism of the expansion device 801 will
be described.
[0155] As shown in FIGS. 15A and 15C, in the expansion device 801,
when the differential pressure across the expansion device 801 has
become equal to or higher than a predetermined value to cause the
valve portion 822 to start to be moved away the valve seat 12, part
of refrigerant flowing in from the upstream side is leaked through
the gap between the valve element 820 and the small pipe portion
13. Further, when the upstream end of the valve element 820 is
moved away from the small pipe portion 13, the refrigerant is
allowed to escape at a larger flow rate, whereby the refrigerant is
allowed to escape into the other flow passage than the refrigerant
passage 824 through the valve element 820 in a stepwise increasing
manner, to thereby allow the refrigerant to flow downstream.
[0156] FIG. 16 is an explanatory view showing the relationship
between the differential pressure across the expansion device 801
and the opening area of the refrigerant passage(s) thereof.
[0157] As shown in FIG. 16, so long as the valve element 820 is
seated on the valve seat 12 (state shown in FIG. 15A), even if the
differential pressure rises, the opening area is held at the
cross-sectional area of the refrigerant passage 824. Then, when the
differential pressure becomes higher than a predetermined value,
the aforementioned gap provides an opening, which once increases
the opening area (state shown in FIG. 15B). Thereafter, as the gap
continues to provide a fixed opening area, the differential
pressure across the expansion device 801 further rises, which
causes the upstream end of the valve element 820 to be moved away
from the small pipe portion 13, which instantly increases the
opening area in response to a change in the differential pressure
across the expansion device 801 (state shown in FIG. 15C).
[0158] As described above, in the expansion device 801 according to
the present embodiment, the refrigerant flowing in from the
upstream side is allowed to escape in a stepwise manner. As a
result, it is possible to prevent an abnormal rise in the
refrigerant pressure inside the expansion device 801, to thereby
prevent breakage or the like of the internal components. Further,
by the stepwise relief of the refrigerant pressure, the flow
characteristics representative of the differential pressure and the
opening area of the refrigerant passage by the expansion device 801
can be set differently from those of the first embodiment.
[0159] It should be noted that such flow characteristics can be
also realized in the sixth and seventh embodiments described
above.
Ninth Embodiment
[0160] Next, a ninth embodiment of the present invention will be
described. FIGS. 17A to 17C are longitudinal cross-sectional views
of an expansion device according to the present embodiment, and
FIG. 18 is a cross-sectional view taken on line H-H of FIG. 17A. It
should be noted that since most of the components of the expansion
device according to the present embodiment are similar to those of
the first embodiment, components similar to those of the first
embodiment will be designated by identical reference numerals, and
description thereof is omitted.
[0161] As shown in FIG. 17A, the expansion device 901 comprises a
cylinder 10 in the form of a hollow cylinder, and a valve element
920 in the form of a hollow cylinder inserted in the cylinder
10.
[0162] The valve element 920 includes a body 921 in the form of a
stepped hollow cylinder inserted in the cylinder 10, and a valve
portion 922 is formed at an upstream end of the body 921, for being
removably seated on the valve seat 12, with a refrigerant passage
924 axially extending through the body 921 to allow passage of
refrigerant.
[0163] The refrigerant passage 924 has a stepped portion 925 which
is expanded from the upstream side to the downstream side, and into
the expanded side of the stepped portion 925 there is inserted an
inner shaft member 930 which functions as a restriction mechanism.
In the present embodiment, the stepped portion 925 is disposed at a
location downstream of the guided portion 23, and the inner shaft
member 930 is formed to be axially shorter than the inner shaft
member 30 of the first embodiment.
[0164] Further, as shown in FIG. 18, a portion of a side wall
slightly downstream of the stepped portion 925 of the valve element
920 is formed with a communication hole 941 communication between
the inside and outside of the restriction passage 924.
[0165] Next, the pressure-cancelling structure of the expansion
device 901 is the same as that of the first embodiment in that the
resultant of the pressure received at the valve-closing
pressure-receiving surface 927 of the stepped portion 925 and the
elastic force of the spring 18 acts against the refrigerant
pressure received at the valve-opening pressure receiving surface
26.
[0166] Next, the relief mechanism of the expansion device 901 will
be described.
[0167] As shown in FIGS. 17A and 17C, in the expansion device 901,
when the valve element 920 is seated, the communication hole 941 is
opened, which allows part of the refrigerant flowing through the
refrigerant passage 924 to escape into another flow passage, and
when the differential pressure across the expansion device 901 has
become equal to or higher than a predetermined value to cause the
valve portion 922 to start to be moved away the valve seat 12, the
upstream end of the inner shaft member 930 closes the communication
hole 941. Then, as soon as the upstream end of the valve element
920 is removed from the small pipe portion 13, most of the
refrigerant flowing in from the upstream side is allowed to escape
through a gap between the valve portion 922 and the valve seat 12,
and flow downstream via the refrigerant passage formed between the
valve element 920 and the cylinder 10 and the plurality of slots
17b of the stopper 17. This prevents an abnormal rise in the
refrigerant pressure inside the expansion device 901.
[0168] FIG. 19 is an explanatory view explanatory view showing the
relationship between the differential pressure across the expansion
device 901 and the opening area of the refrigerant passage(s)
thereof.
[0169] As shown in FIG. 19, so long as the valve element 920 is
seated on the valve seat 12 (state shown in FIG. 17A), even if the
differential pressure rises, the opening area is held at the sum of
the cross-sectional area of the refrigerant passage 924 and that of
the communication hole 942. Then, when the differential pressure
becomes higher than a predetermined value, the communication hole
941 starts to be closed, and therefore the cross-sectional area is
once decreased (state shown in FIG. 17B). When the differential
pressure further rises thereafter, the upstream end of the valve
element 920 is removed from the small pipe portion 13, which
instantly increases the opening area in response to a change in the
differential pressure (state shown in FIG. 17C).
[0170] As described above, in the expansion device 901 according to
the present embodiment, e.g. by once stopping the escape of the
refrigerant flowing in from the upstream side to once decrease the
opening area, the flow characteristics representative of
relationship between the differential pressure of the expansion
device 901 and the opening area of the refrigerant passage(s)
thereof can be set differently from those of the first
embodiment.
[0171] Further, the cooling performance of the expansion device 901
can be also enhanced e.g. by increasing the degree of supercooling
(subcooling) by once decreasing the opening area to thereby
temporarily decrease the flow rate of the refrigerant.
Tenth Embodiment
[0172] Next, a tenth embodiment of the present invention will be
described. The present embodiment is an application of the
configuration of the ninth embodiment to that of the second
embodiment. FIGS. 20A to 20C are cross-sectional views of an
expansion device according to the present embodiment, and FIG. 21
is a cross-sectional view taken on line I-I of FIG. 20A. It should
be noted that since most of the components of the expansion device
according to the present embodiment are similar to those of the
second embodiment, components similar to those of the second
embodiment will be designated by identical reference numerals, and
description thereof is omitted.
[0173] As shown in FIG. 20A, the expansion device 1001 comprises a
cylinder in the form of a hollow cylinder 210, and a valve element
1020 in the form of a hollow cylinder inserted in the cylinder
210.
[0174] As shown in FIG. 21 as well, a portion of the side wall of
the valve element 1020 at a location opposed to the space portion
241 on the downstream side of the valve portion 222 is formed with
a communication hole 1041 which communicates between the inside and
the outside of the refrigerant passage 224.
[0175] Next, the relief mechanism of the expansion device 1001 will
be described.
[0176] As shown in FIGS. 20A to 20C, in the expansion device 1001,
when the valve element 1020 is seated, the communication hole 1041
is opened, which allows part of the refrigerant flowing through the
refrigerant passage 224 to be introduced into the refrigerant
passage formed between the piping 50 and the cylinder 210 via the
space portion 241 and the communication holes 214a, to flow
downstream. Then, when the differential pressure across the
expansion device 1001 has become equal to or higher than a
predetermined value to cause the valve portion 222 to start to be
moved away the valve seat 212, the valve element 1020 is moved
downstream, whereby the communication hole 1041 is closed by the
guide pipe portion 215. Then, when the upstream end of the valve
element 1020 is removed from the valve seat portion 213, most of
the refrigerant flowing in from the upstream side is allowed to
escape via a gap created between the valve portion 222 and the
valve seat 212, to flow downstream. This prevents an abnormal rise
in the refrigerant pressure inside the expansion device 1001.
[0177] As described above, in the expansion device 1001 according
to the present embodiment, with the provision of the communication
hole 1041, the refrigerant flowing in from the upstream side is
allowed to escape in a stepwise manner. As a result, the flow
characteristics representative of the relationship between the
differential pressure across the expansion device 1001 and the
opening area of the refrigerant passage(s) of the same can be set
differently from those of the second embodiment.
[0178] Further, the cooling performance of the expansion device
1001 can be also enhanced e.g. by increasing the degree of
supercooling (subcooling) by once decreasing the opening area to
thereby temporarily decrease the flow rate of the refrigerant.
Eleventh Embodiment
[0179] Next, an eleventh embodiment of the present invention will
be described. The present embodiment is an application of the
configuration of the ninth embodiment to a part of the
configuration similar to the corresponding part of the seventh
embodiment. FIGS. 22A to 22C are cross-sectional views of an
expansion device according to the present embodiment, and FIG. 23
is a cross-sectional view taken on line J-J of FIG. 22A. It should
be noted that components similar to those of the seventh embodiment
will be designated by identical reference numerals, and description
thereof is omitted.
[0180] As shown in FIG. 22A, the expansion device 1101 comprises a
first relief mechanism 710 inserted in a upstream part of the
cylinder 702, and a second relief mechanism 1220 inserted in a
downstream part of the same.
[0181] The second relief mechanism 1220 comprises a second valve
element 1120, and a stopper 750.
[0182] The second valve element 1120 has a body in the form of a
stepped hollow cylinder. An upstream end of the body is reduced in
a tapered manner, and from the forward end of the reduced portion
axially extends a guided portion 1122, and a downstream end of the
same is formed with a flange 1123 which extends radially outward.
The guided portion 1122 is inserted in the stopper 750 in the form
of a hollow cylinder such that it is slidably held therein, and a
stepped portion 1125 formed inside the tapered portion. The
cross-section of the downstream side of the stepped portion 1125 is
larger than that of the passage cross-section of the stopper 750.
Further, the outer surface of the tapered portion forms a valve
portion 1121 which can be seated on the valve seat 752 on the
downstream end of the stopper 750.
[0183] Further, as also shown in FIG. 23, a portion of the side
wall of the guided portion 1122 in the vicinity of the tapered
portion is formed with a communication hole 1141 that communicates
between the inside and the outside of the refrigerant passage 1124.
On the other hand, the downstream end of the valve element 1120 has
a tapered shape the outer diameter of which decreases downstream,
and is in abutment with the end face of the stopper 17. The
refrigerant passage formed between the valve element 1120 and the
cylinder 702 communicates with the slots 17b. A spring 1118 is
interposed between the flange 1123 and the downstream end face of
the stopper 750, for urging the second valve element 1120 in the
downstream direction.
[0184] Next, the relief mechanism of the expansion device 1101 will
be described.
[0185] As shown in FIGS. 22A to 22C, in the expansion device 1101,
when the differential pressure across the expansion device 1101 is
lower than the second predetermined value, the valve element 1120
is not seated, so that the communication hole 1141 is made open, to
allow part of the refrigerant flowing through the refrigerant
passage 1124 to be introduced into the refrigerant passage formed
between the valve element 1120 and the cylinder 702 via the
communication hole 1141, and flow downstream via the outside of the
flange 1123 and the slots 17b. Then, when the differential pressure
has become equal to or higher than the second predetermined value
to cause the valve element 1121 to start to be moved toward the
valve seat 752, the second valve element 1120 is moved upstream, so
that the stopper 750 starts to close the communication hole 1141.
When the valve element 1121 is seated on the valve seat 752, the
communication hole 1141 is completely closed.
[0186] Further, when the differential pressure has become equal to
or higher than the first predetermined value larger than the second
predetermined value, the first relief mechanism 710 operates as
described hereinabove. More specifically, the valve portion 22 of
the valve element 20 is moved away from the valve seat 12, to allow
most of refrigerant flowing in from the upstream side to escape
through a gap between the valve portion 22 and the valve seat 12,
and flow downstream through a refrigerant passage formed between
the first valve element 20 and the cylinder 702, and refrigerant
passages formed between the cutout portion 753 and the cylinder 702
and between the valve element 1120 of the second relief mechanism
1220 and the cylinder 702. This prevents an abnormal rise in the
refrigerant pressure inside the expansion device 1101.
[0187] FIG. 24 is an explanatory view showing the relationship
between the differential pressure across the expansion device 1101
and the opening area of the refrigerant passage(s) thereof.
[0188] As shown in FIG. 24, before the second valve element 1120 is
seated on the valve seat 752, even if the differential pressure
rises, the opening area is held at the sum of the cross-sectional
area of the refrigerant passage 1124 and that of the communication
hole 1141 (state shown in FIG. 22A). Then, when the differential
pressure becomes higher than a second predetermined value, the
communication hole 1141 starts to be closed to once decrease the
area of the opening, and when the communication hole 1141 is
completely closed, the opening area is held constant again (state
shown in FIG. 22B). Thereafter, when the differential pressure
across the expansion device 1101 further rises, the valve portion
22 of the first relief mechanism 710 is removed from the valve seat
12, which instantly increases the opening area in response to a
change in the differential pressure across the expansion device
1101(state shown in FIG. 22C).
[0189] As described above, in the expansion device 1101 according
to the present embodiment, with the provision of the communication
hole 1141, the refrigerant flowing in from the upstream side is
allowed to escape in a stepwise manner. As a result, the flow
characteristics representative of the relationship between the
differential pressure across the expansion device 1101 and the
opening area of the refrigerant passage(s) of the same can be set
differently from those of the seventh embodiment.
[0190] Further, it is possible to enhance the cooling performance
of the expansion device 1101 as well by once decreasing the opening
area to temporarily decrease the flow rate of refrigerant, to
thereby enhance the supercooling degree.
Twelfth Embodiment
[0191] Next, a twelfth embodiment of the present invention will be
described. FIGS. 25A and 25B are longitudinal cross-sectional views
of an expansion device according to the present embodiment. FIGS.
26A and 26B are transverse cross-sectional views of the expansion
device, in which FIG. 26A is a cross-sectional view taken on line
K-K of FIG. 25A, and FIG. 26B is a cross-sectional view taken on
line L-L of FIG. 25A. It should be noted that most of the
configuration of the expansion device according to the present
embodiment is similar to that of the first embodiment, and
therefore description thereof is omitted by designating similar
components with identical reference numerals.
[0192] As shown in FIG. 25A, in the expansion device 1201, an inner
shaft member 1230 is configured as a solid member having a
cylindrical shape, which has a downstream end thereof fixed to a
stopper 1217, referred to hereinafter. As shown in FIG. 26A as
well, the outer diameter of the inner shaft member 1230 is smaller
than the inner diameter of a stepped portion 25 of the valve
element 20 by a predetermined amount, whereby a gap 1225 is formed
between the inner shaft member 1230 and the inner wall of the valve
element 20. This gap 1225 communicates with the refrigerant passage
24 and functions as the restriction mechanism.
[0193] Further, the stopper 1217 has a shape similar to that of the
stopper 17 of the first embodiment, but a pair of slots 1217a are
provided in upper and lower halves of the bottom thereof as viewed
in FIG. 26B, and a fixing portion 1217b having a circular shape is
formed between the slots 1217a, for fixing one end of the inner
shaft member 1230 thereto.
[0194] Next, the relief mechanism of the expansion device 1201 will
be described.
[0195] As shown in FIGS. 25A and 25B, in the expansion device 1201,
the valve element 20 is seated on the valve seat 12 when the
differential pressure thereacross is lower than a predetermined
value. Therefore, when the refrigerant flowing in from the upstream
side is introduced into the refrigerant passage 24, it is
decompressed as it passes through the gap 1225, and flows
downstream via the slots 1217a.
[0196] Then, when the differential pressure across the expansion
device 1201 has become equal to or larger than the predetermined
value to cause the valve portion 22 to be moved away from the valve
seat 12, most of the refrigerant flowing in from the upstream side
is allowed to escape through the refrigerant passage formed between
the valve element 20 and the cylinder 10 and flow downstream.
[0197] In the expansion device 1201 described above, the inner
shaft member 1230 is fixed to the stopper 1217, which makes it
possible to hold the gap 1225 substantially constant, thereby
securing the repeatability of the refrigerant flow.
[0198] When the repeatability of the refrigerant flow does not
matter, the inner shaft member 1230 need not be fixed to the
stopper 1217.
Thirteenth Embodiment
[0199] Next, a thirteenth embodiment of the present invention will
be described. FIGS. 27A to 27C are cross-sectional views of an
expansion device according to the present embodiment. FIG. 27C is a
cross-sectional view taken on line M-M of FIG. 27A. It should be
noted that most of the configuration of the expansion device
according to the present embodiment is similar to that of the
eleventh embodiment, and therefore description thereof is omitted
by designating similar components with identical reference
numerals.
[0200] As shown in FIG. 27A, in the expansion device 1301, the
valve element 1320 has a structure corresponding to the second
valve element 1120 of the eleventh embodiment, but in this
structure, the communication hole 1141 is not formed, and a guided
portion 1122 is inserted into the small pipe portion 13 such that
it is axially slidably supported therein. Further, the downstream
end of the valve element 1320 forms a valve portion 1321, and is
configured such that it can be seated on the upstream end face
(valve seat) of a stopper 17 disposed on the downstream side.
Further, a spring 1118 is interposed between a flange 1123 of the
valve element 1320 and a stepped portion of the cylinder 1310, for
urging the valve element 1320 in the downstream direction.
[0201] Further, as shown in FIG. 27C as well, on the downstream
side of the valve element 1320, an inner shaft member 1330 in the
form of a cylinder is inserted which has a cutout portion 1330a
formed by cutting off a side portion along the axis thereof while
leaving a downstream end uncut, whereby a refrigerant passage 1331
is formed between the cutout portion 1330a and the inner surface of
the valve element 1320.
[0202] Next, the relief mechanism of the expansion device 1301 will
be described.
[0203] As shown in FIGS. 27A and 27B, in the expansion device 1301,
the valve element 1320 is seated on the upstream end face of the
stopper 17 when the differential pressure thereacross is lower than
a predetermined value. Therefore, when the refrigerant flowing in
from the upstream side is introduced into the refrigerant passage
1124, it is decompressed by passing through the restriction
extending through the inner shaft member 1330, and flows downstream
via the through hole 17a.
[0204] Then, when the differential pressure across the expansion
device 1301 has become equal to or larger than the predetermined
value to cause the valve portion 1321 to be moved away from the
stopper 17, the refrigerant passage 1331 is made open to the
cylinder 1310, to thereby allow most of the refrigerant flowing in
from the upstream side to escape downstream through the refrigerant
passage 1331, between the inner shaft member 1330 and the cylinder
1310, and the slots 17b.
Fourteenth Embodiment
[0205] Next, a fourteenth embodiment of the present invention will
be described. FIGS. 28A to 28C are cross-sectional views of an
expansion device according to the present embodiment. FIG. 29 is a
cross-sectional view taken on line N-N of FIG. 28A. It should be
noted that most of the configuration of the expansion device
according to the present embodiment is similar to that of the
thirteenth embodiment, and therefore description thereof is omitted
by designating similar components with identical reference
numerals.
[0206] As shown in FIGS. 28A and 29, the expansion device 1401
includes an inner shaft member 1430 which is a modification of the
inner shaft member 1330 in the thirteenth embodiment in which a
groove 1430a having a predetermined width is formed in the inner
shaft member 1330 at a location circumferentially shifted from the
cutout portion 1330a, in side view. The groove 1430a extends
further downstream with respect to the cutout portion 1330a by a
predetermined amount, thereby forming a refrigerant passage 1432
having a smaller passage cross-section than that of the refrigerant
passage 1331, between the groove 1430a and the inner surface of the
valve element 1320.
[0207] Next, the relief mechanism of the expansion device 1401 will
be described.
[0208] As shown in FIGS. 28A to 28C, in the expansion device 1401,
when the differential pressure across the expansion device 1401 has
become equal to or higher than a predetermined value to cause the
valve portion 1321 to start to be moved away the stopper 17, first,
the refrigerant passage 1432 is made open to the cylinder 1310 to
thereby allow part of refrigerant flowing in from the upstream side
to escape downstream through the refrigerant passage 1432, a flow
passage formed between the inner shaft member 1430 and the cylinder
1310, the slots 17b. Then, when the differential pressure becomes
still higher, the valve element 1320 is moved further upstream to
open the refrigerant passage 1331, to thereby allow most of the
refrigerant flowing in from the upstream side to escape downstream
via the refrigerant passage 1331, the flow passage between the
inner shaft 1430 and the cylinder 1310, and the slots 17b.
Fifteenth Embodiment
[0209] Next, a fifteenth embodiment of the present invention will
be described. FIGS. 30A to 30C are longitudinal cross-sectional
views of an expansion device according to the present embodiment.
It should be noted that most of the configuration of the expansion
device according to the present embodiment is similar to that of
the thirteenth embodiment, and therefore description thereof is
omitted by designating similar components with identical reference
numerals.
[0210] As shown in FIG. 30A, a valve element 1520 of the expansion
device 1501 has a guided portion 1442 as a modification of the side
wall of the guided portion 1122, through which is formed a
communication hole 1521 communicating between the inside and
outside of the refrigerant passage 1124, at a location in the
vicinity of the tapered portion on the upstream side of the valve
element 1320 in the thirteenth embodiment.
[0211] Next, the relief mechanism of the expansion device 1501 will
be described.
[0212] As shown in FIGS. 30A and 30C, in the expansion device 1501,
when the differential pressure across the expansion device 1501 is
lower than the second predetermined value, the communication hole
1521 is made open, to allow part of the refrigerant flowing through
the refrigerant passage 1124 to be introduced into the refrigerant
passage formed between the valve element 1520 and the cylinder 1310
via the communication hole 1521, and flow downstream via the
outside of the flange 1123 and the slots 17b. Then, when the
differential pressure has become equal to or higher than the second
predetermined value, to cause the valve element 1520 to be moved
upstream, the small pipe portion 13 closes the communication hole
1521.
[0213] Further, when the differential pressure has become equal to
or higher than the first predetermined value larger than the second
predetermined value, the valve element 1520 is moved further
upstream whereby the refrigerant passage 1331 is made open, to
thereby allow most of refrigerant flowing in from the upstream side
to escape through the refrigerant passage 1331, a flow passage
between the inner shaft member 1330 and the cylinder 1310, and the
slots 17b.
Sixteenth Embodiment
[0214] Next, a sixteenth embodiment of the present invention will
be described. FIGS. 31A and 31B are cross-sectional views of an
expansion device according to the present embodiment. It should be
noted that the expansion device according to the present embodiment
has such a configuration as a combination of the twelfth embodiment
and the thirteenth embodiment, and therefore description of
components of the present embodiment similar to those of these
embodiments is omitted while designating the similar components
with identical reference numerals.
[0215] As shown in FIG. 31A, in the expansion device 1601, an inner
shaft member 1630 is configured as a solid member in the form of a
cylinder, which has a downstream end thereof fixed to a stopper
1217. The diameter of the inner shaft member 1630 is smaller than
the inner diameter of the stepped portion 1125 of the valve element
1320 by a predetermined amount, whereby a gap 1625 is formed
between the inner shaft member 1630 and the inner wall of the valve
element 1320. This gap 1625 communicates with the refrigerant
passage 1124 and functions as the restriction mechanism. Further,
the inner shaft member 1630 is formed with a cutout portion 1630a
which is formed by cutting off a portion thereof along the axis,
while leaving a downstream end thereof uncut, whereby a flow
passage 1631 is formed between the cutout portion 1630a and the
inner surface of the valve element 1320.
[0216] Next, the relief mechanism of the expansion device 1601 will
be described.
[0217] As shown in FIGS. 31A and 31B, in the expansion device 1601,
when the differential pressure thereacross is lower than a
predetermined value, the refrigerant flowing in from the upstream
side is decompressed by passing through the gap 1625, and flows
downstream via slots 1217a.
[0218] Then, when the differential pressure across the expansion
device 1601 has become equal to or larger than the predetermined
value to cause the valve portion 1321 to be moved away from the
stopper 1217, most of the refrigerant flowing in from the upstream
side is allowed to escape downstream through the refrigerant
passage 1631, a flow passage between the inner shaft member 1630
and the cylinder 1310, and the slots 17b.
Seventeenth Embodiment
[0219] Next, a seventeenth embodiment of the present invention will
be described. FIGS. 32A and 32B are longitudinal cross-sectional
views of an expansion device according to the present embodiment.
Further, FIGS. 33A and 33B are transverse cross-sectional views of
the expansion device, in which FIG. 33A is a cross-sectional view
taken on line O-O of FIG. 32A, and FIG. 33B is a view taken from a
direction of P of FIG. 32A. It should be noted that components
similar to those of the first embodiment will be designated by
identical reference numerals, and description thereof is
omitted.
[0220] The present embodiment realizes a configuration that
enhances the accuracy of the pressure cancellation. More
specifically, similarly to the first embodiment as shown in FIG. 2,
in a configuration where the pressure-receiving surface of the
valve portion 22 has a tapered shape, the effective
pressure-receiving area of the valve element 20 tends to become
smaller as the valve element 20 is moved away from the valve seat
12. As a result, actually, as designated by dotted line in FIG. 35,
with a rise in the differential pressure, the rate of increase in
the opening area is lowered to cause the balance of the pressure
cancellation to be lost, or degrade the relieving operation. The
expansion device 1701 according to the present embodiment solves
the problem.
[0221] As shown in FIG. 32A, the expansion device 1701 comprises a
cylinder 10 in the form of a hollow cylinder, and a valve element
1270 in the form of a hollow cylinder inserted in the cylinder 10.
A large pipe portion 14 of the cylinder 10 has a stopper 1717 in
the form of a disk fixed thereto at a location in the vicinity of
the downstream end thereof, and a spring 18 is interposed between
the stopper 1717 and the valve element 1720, for urging the valve
element 1720 toward a valve seat 12 (in the valve-closing
direction).
[0222] The valve element 1720 comprises a body in the form of a
stepped hollow cylinder inserted in the cylinder 10, a valve
portion 1721 in the form of a hollow cylinder which can be
removably seated on the valve seat 12, and a guided portion 1722 in
the form of a stepped hollow cylinder disposed on the downstream
side of the valve portion 1721.
[0223] The upstream end of the valve portion 1721 is provided with
a tapered portion the outer diameter of which decreases upstream,
and when the valve portion 1721 is seated, the foremost end of the
tapered portion 1721 is inserted into the small pipe portion 13 by
a predetermined amount.
[0224] As shown in FIG. 33A, the guided portion 1722 comprises a
body 1723 having a generally hexagonal cross-section, and a reduced
pipe portion 1724 in the form of a hollow cylinder formed
continuous with the downstream side of the body 1723. Each vertex
portion of the body 1723 is configured to have an arcuate shape
extending along the inner peripheral surface of the large pipe
portion 14, and refrigerant passages are formed between the vertex
portions, which allow passage of refrigerant. The valve element
1720 is stably moved forward and backward within the cylinder 10,
with the vertex portions sliding along the inner surface of the
large pipe portion 14. Further, the reduced pipe portion 1724 has
one end of the spring 18 fitted thereon.
[0225] The upstream end of the body 1723 is slightly expanded, and
the downstream end of the valve portion 1721 is press-fitted
therein. Therefore, a space portion S1 is formed between the valve
portion 1721 and the reduced pipe 1724 of the guided portion 1722.
In this space portion S1, a shaft-like member 1730 in the form of a
stepped cylinder, referred to hereinafter, is partially
inserted.
[0226] The stopper 1717 is, as shown in FIG. 33B as well, formed
with a screw hole 1717a extending through the center thereof.
Around the screw hole 1717a, there are formed three elongated holes
1717b at equal intervals (of 120 degrees). The flow passage area as
the sum of the these three elongated holes 1717b is sufficiently
larger than that of the flow passage formed by a gap created
between the valve portion 1721 and the valve seat 12, which
prevents pressure loss of the refrigerant from occurring in the
elongated holes 1717b. The stopper 1717 is equipped with an
adjusting mechanism, that is, the stopper 1717 has an outer
periphery formed with an external thread, and a downstream end of
the cylinder 10 is formed with an internal thread mating with the
external thread. By adjusting the amount of screwing of the stopper
1717 into the cylinder 10, the position of the stopper 1717 is
adjusted, whereby the elastic force of the spring 18 can be
adjusted. Further, through the screw hole 1717a of the stopper
1717, there is inserted a set screw 1740 (engaging member) with a
slotted head or a hexagon socket by screwing, such that a foremost
end thereof holds the downstream end face of the shaft-like member
1730. By adjusting the amount of screwing of the set screw 1740
with respect to the stopper 1717, the position of the set screw
1740 is adjusted, whereby the axial position of the shaft-like
member 1730 within the cylinder 10 can be adjusted.
[0227] FIGS. 34A to 34C are explanatory views showing the
configuration of the restriction mechanism according to the present
embodiment, in which FIG. 34A is a partial expanded cross-sectional
view showing the configuration of the vicinity of the valve element
1720, and FIGS. 34B and 34C show expanded views of Q portion in
FIG. 34A.
[0228] As shown in 34A, the shaft-like member 1730 has an upstream
end thereof formed with a tapered portion 1731 the cross-section of
which increases upstream. A restriction passage is formed by a gap
between the tapered surface of the tapered portion 1731 and an
inner peripheral edge 1724a of the reduced pipe portion 1724. As
shown in FIG. 34B, so long as the valve element 1720 is seated on
the valve seat 12, the restriction passage holds the gap at a
predetermined value c1 which realizes the passage cross-section of
the normal restriction mechanism. Therefore, the refrigerant
pressure is high on the upstream side of the gap, and low on the
downstream side of the same. However, as shown FIG. 34C, when the
valve element 1720 is moved away from the valve seat 12, the gap
has become equal to a value c2 larger than the predetermined value
c1, which makes it possible to allow the refrigerant to flow at a
larger flow rate, but on the other hand, the function of the
restriction mechanism is lowered. It should be noted that the size
of the restriction passage in the closed state of the valve can be
freely set by adjusting the position of the shaft-like member 1730
using the adjusting mechanism described above.
[0229] Further, the upstream end face of the shaft-like member 1730
is formed with a groove 1732 extending diametrically therethrough,
as shown in FIG. 33A, and the remaining portion of the end face is
capable of holding the valve portion 1721, and hence the valve
element 1720 from the downstream side. Further, since the groove
1732 communicates with the refrigerant passage extending through
the valve portion 1721, even when the valve portion 1721 is engaged
with the shaft-like member 1730, the refrigerant can be allowed to
flow through the communication passage formed by the groove 1732,
the space portion S1, and the reduced pipe portion 1724.
[0230] Next, the pressure-cancelling structure of the expansion
device 1701 will be described.
[0231] In the expansion device 1701, as shown in FIG. 34B, to
receive the high-pressure refrigerant introduced from the upstream
side into the refrigerant passage in the small pipe portion 13, a
valve-opening pressure-receiving surface is formed by a portion
1751 of the upstream end face of the valve portion 1721, which is
inserted into the small pipe portion 13, and an upstream end face
1752 of the reduced pipe portion 1724 of the guided portion 1722,
and a valve-closing pressure-receiving surface is formed by the
downstream end face 1753 of the valve portion 1721. Further, the
inner diameter of the reduced pipe portion 1724 is made smaller
than that of the small pipe portion 13 (see dotted lines in FIG.
34B) such that the pressure-receiving area of the entire
valve-opening pressure-receiving surface becomes larger than the
pressure-receiving area of the entire valve-closing
pressure-receiving surface. That is, the refrigerant introduced
into the space SI within the valve element 1720 acts to urge the
valve element 1720 in the valve-closing direction (rightward as
viewed in FIG. 34A) to thereby cancel part of the refrigerant
pressure acting on the valve element 1720 in the valve-opening
direction. Therefore, the resultant of the pressure received at the
valve-closing pressure-receiving surface and the elastic force of
the spring 18 acts against the refrigerant pressure received at the
valve-opening pressure-receiving surface.
[0232] Next, the relief mechanism of the expansion device 1701 will
be described.
[0233] As shown in FIGS. 32A and 32B, in the expansion device 1701,
when the differential pressure across the expansion device 1701 has
become equal to or higher than a predetermined value to cause the
valve portion 1721 to be moved away the valve seat 12, most of
refrigerant flowing in from the upstream side is allowed to escape
through a gap between the valve portion 1721 and the valve seat 12,
and flow downstream through a refrigerant passage formed between
the valve element 1720 and the cylinder 10 and the elongated holes
1717b of the stopper 1717. This prevents an abnormal rise in the
refrigerant pressure inside the expansion device 1701.
[0234] FIG. 35 is an explanatory view showing the relationship
between the differential pressure across the expansion device 1701
and the opening area of the refrigerant passage(s) thereof.
[0235] As shown in FIG. 35, so long as the valve element 1720 is
seated on the valve seat 12 (state shown in FIG. 32A), even if the
differential pressure rises, the opening area is held constant by
being limited by the restriction passage. Then, when the
differential pressure becomes higher than a predetermined value,
the valve element 1720 is moved away from the valve seat 12 to
allow the refrigerant to escape into the outside refrigerant
passage to relieve the pressure. Thus, the opening area is
instantly increased (state shown in FIG. 32B). In this case, it is
possible to prevent or suppress the lowering in the rate of
increase in the opening area which might occur as the differential
pressure across the expansion device 1701 rises as shown by a
dotted line in FIG. 35, whereby it is possible to prevent the
characteristics of the expansion device from being changed due to
lowering in the received pressure, as shown by a solid line,
thereby enabling the refrigerant to escape such that the
refrigerant pressure is sufficiently relieved.
[0236] It is presumed that this is because a change (decrease) in
the effective pressure-receiving area of the valve element 1720 and
a change (increase) in the effective pressure-receiving area of the
reduced pipe portion 1724 are cancelled each other, which makes it
possible to cancel variation in the received pressure caused by the
lift of the valve element 1720.
[0237] As described above, in the expansion device 1701 U according
to the present embodiment, since the pressure-cancelling structure
cancels part of the refrigerant pressure, a small-sized spring can
be employed for the spring 18. As a result, it is possible to make
the entire expansion device 1701 compact in size.
[0238] Further, when the differential pressure across the expansion
device 1701 has become equal to or higher than the predetermined
value, the refrigerant flowing in from the upstream side can be
allowed to escape into the other flow passage than the normal
refrigerant passage extending by way of the restriction passage,
which makes it possible to prevent an abnormal rise in the
refrigerant pressure inside the expansion device 1701, to thereby
prevent breakage or the like of the internal components.
[0239] Further, as described above, the passage cross-section of
the restriction passage on the downstream side is increased
according to the valve opening condition of the valve element 1720.
This prevents variation in the characteristics caused by the
decrease in the received pressure, maintains the balance of the
pressure cancellation, and improves the relieving operation.
[0240] Although in the present embodiment, the inner diameter of
the reduced pipe portion 1724 is smaller than that of the small
pipe portion 13, this is not limitative, but these inner diameters
may be made equal to each other. Even with this configuration, due
to the configuration in which the passage cross-section of the
restriction passage on the downstream side is increased, it is
possible to expect the effects of maintaining the balance of the
pressure cancellation and the like.
[0241] Further, there may be provided a guide means for stably
holding the shaft-like member 1730 within the cylinder 10. For
example, the shaft-like member 1730 may be formed with a plurality
of guide portions which extend radially outward from the outer
peripheral surface of an upstream end thereof, so as to be guided
by the inner peripheral surface of the guided portion 1722 of the
valve element 1720.
Eighteenth Embodiment
[0242] Next, an eighteenth embodiment of the present invention will
be described. FIGS. 36A and 36B are longitudinal cross-sectional
views of an expansion device according to the present embodiment.
Further, FIGS. 37A and 37B are transverse cross-sectional views of
the expansion device, in which FIG. 37A is a cross-sectional view
taken on line R-R of FIG. 36A, and FIG. 37B is a view taken from a
direction of S of FIG. 36A. It should be noted that components
similar to those of the first embodiment will be designated by
identical reference numerals, and description thereof is
omitted.
[0243] As shown in FIG. 36A, the expansion device 1801 comprises a
cylinder 10 in the form of a hollow cylinder, a valve element 1820
in the form of a hollow cylinder inserted in the cylinder 10, and a
ball valve seat 1830 in the form of a ball supported within the
cylinder 10. In the vicinity of the downstream end of the large
pipe portion 14 of the cylinder 10, a stopper 1817 in the form of a
bottomed hollow cylinder is secured, with the ball valve seat 1830
being interposed between the stopper 1817 and the valve element
1820. Further, a spring 18 is interposed between the downstream end
face of the small pipe portion 13 and the valve element 1820, for
urging the valve element 1820 toward the ball valve seat 1830 (in
the valve-closing direction).
[0244] The valve element 1820 has a body in the form of a stepped
hollow cylinder which is expanded downstream in two stages. A
hollow cylindrical portion as a central part of the body forms a
body portion 1821, with a reduced pipe portion 1822 formed on the
upstream side of the body portion 1821 by reducing the diameter of
a corresponding portion of the body, and a guide portion 1823
formed on the downstream side of the body portion 1821 by
increasing the diameter of a corresponding portion of the body.
Further, a valve portion 1824 in the form of a hollow cylinder is
formed by a downstream end of the body portion 1821.
[0245] The reduced pipe portion 1822 has an outer diameter slightly
smaller than that of the small pipe portion 13, and movably
inserted in the small pipe portion 13. The gap between the reduced
pipe portion 1822 and the small pipe portion 13 forms a restriction
passage (restriction mechanism). The junction of the reduced pipe
portion 1822 and the body portion 1821 has a tapered shape in which
the outer diameter thereof decreases toward the upstream end of the
body.
[0246] As shown in FIG. 37A, the guide portion 1823 has an
approximately hexagonal cross-section, and vertex portions each
have an arcuate shape extending along the inner peripheral surface
of the large pipe portion 14, defining refrigerant passages
therebetween which allow passage of refrigerant. The vertex
portions of the guide portion 1823 are slid along the inner surface
of the large pipe portion 14, whereby the valve portion 1820 can be
stably moved forward and backward within the cylinder. Further, the
inside of the guide portion 1823 has a tapered shape in which the
cross-section thereof is increased downstream, and a downstream end
face of the tapered portion facing downstream can receive the ball
valve seat 1830 in a manner covering an upstream portion of the
ball valve seat 1830. As shown in FIG. 36A, when the valve portion
1824 of the valve element 1820 is seated on the ball valve seat
1830, a predetermine gap is formed between the tapered portion and
the ball valve seat 1830. At this time, the ball valve seat 1830 is
supported by the upstream end face of the stopper 1817 and the
valve portion 1824 in a manner sandwiched therebetween. The
aforementioned spring 18 is fitted on the body portion 1821, and
interposed between an upstream end face of the guide portion 1823
and a downstream end face of the small pipe portion 13.
[0247] As shown in FIG. 37B as well, the stopper 1817 is formed
with three slots 1817a around the center thereof at equal intervals
(of 120 degrees), which form refrigerant passages. The
cross-sectional area of a flow passage as the sum of the these
three slots 1817a is sufficiently larger than that of a flow
passage formed by a gap created between the valve portion 1824 and
the ball valve seat 1830, which prevents pressure loss of the
refrigerant from occurring in the slots 1817a. The stopper 1817 is
equipped with an adjusting mechanism, that is, the stopper 1817 has
an outer periphery formed with an external thread, and a downstream
end of the cylinder 10 is formed with an internal thread mating
with the external thread. By adjusting the amount of screwing of
the stopper 1817 into the cylinder 10, the position of the ball
valve seat 1830 supporting on the upstream side is adjusted.
[0248] Next, the pressure-cancelling structure of the expansion
device 1801 will be described,.
[0249] In the expansion device 1801, an upstream end face of the
reduced pipe portion 1822 forms a valve-closing pressure-receiving
surface, and a downstream facing surface of the tapered portion at
the boundary of the reduced pipe portion 1822 and the body portion
1821 within the valve element 1820 forms a valve-opening
pressure-receiving surface larger in pressure-receiving area than
the valve-closing pressure-receiving surface. That is, the
refrigerant introduced from the upstream side acts on the valve
element 1820 in the valve-closing direction (leftward as viewed in
FIG. 36B) to thereby cancel part of the refrigerant pressure acting
on the valve element 1820 in the valve-opening direction.
Therefore, the resultant of the pressure received at the
valve-closing pressure-receiving surface and the elastic force of
the spring 18 acts against the refrigerant pressure received at the
valve-opening pressure-receiving surface.
[0250] Next, the relief mechanism of the expansion device 1801 will
be described.
[0251] As shown in FIGS. 36A and 36B, in the expansion device 1801,
when the differential pressure across the expansion device 1801 has
become equal to or higher than a predetermined value to cause the
valve portion 1824 to be moved away the ball valve seat 1830, most
of refrigerant flowing in from the upstream side is allowed to
escape through a gap between the valve portion 1824 and the ball
valve seat 1830, and flow downstream through the slots 1817a of the
stopper 1817. This prevents an abnormal rise in the refrigerant
pressure inside the expansion device 1801.
[0252] In the expansion device 1801 as well, the relationship
between the differential pressure thereacross and the opening area
of the refrigerant passage(s) is approximately the same as that
shown in FIG. 35.
[0253] That is, so long as the valve element 1820 is seated on the
ball valve seat 1830 (state shown in FIG. 36A), even if the
differential pressure rises, the opening area is held constant by
being limited by the restriction passage formed by the gap between
the reduced pipe portion 1822 and the small pipe portion 13. Then,
when the differential pressure becomes higher than a predetermined
value, the valve element 1820 is moved away from the ball valve
seat 1830 to allow the refrigerant to escape into an inner
refrigerant passage to relieve the refrigerant pressure. Thus, the
opening area is instantly increased (state shown in FIG. 36B).
[0254] As described above, in the expansion device 1801 according
to the present embodiment as well, since the pressure-cancelling
structure cancels part of the refrigerant pressure, it is possible
to make the entire expansion device 1801 compact in size.
[0255] Further, when the differential pressure across the expansion
device 1801 has become equal to or higher than a predetermined
value, the relief mechanism prevents an abnormal rise in the
differential pressure, thereby making it possible to prevent
breakage or the like of the internal components.
[0256] Further, as described above, since the decrease in the
effective pressure-receiving area is small when the valve element
1820 is opened, but on the contrary, the surface thereof urged in
the valve-opening direction is increased, so that it is possible to
increase the accuracy of the pressure cancellation, and cause the
relieving function to operate more rapidly. As a result, the
differential pressure across the expansion device before the
required maximum valve lift is reached can be small, so that the
pressure load on the entire expansion device can be reduced to
protect the same.
Nineteenth Embodiment
[0257] Next, a nineteenth embodiment of the present invention will
be described. FIGS. 38A and 38B are longitudinal cross-sectional
views of an expansion device according to the present embodiment.
Further, FIGS. 39A and 39B are transverse cross-sectional views of
the expansion device, in which FIG. 39A is a cross-sectional view
taken on line T-T of FIG. 38A, and FIG. 39B is a cross-sectional
view taken on line U-U of FIG. 38A. It should be noted that
components similar to those of the first embodiment will be
designated by identical reference numerals, as required, and
description thereof is omitted.
[0258] As shown in FIG. 38A, the expansion device 1901 comprises a
cylinder 10 in the form of a hollow cylinder, and a valve element
1920 in the form of a hollow cylinder inserted in the cylinder 10.
In the vicinity of the downstream end of the large pipe portion 14
of the cylinder 10, a stopper 1917 in the form of a hollow cylinder
is secured. Further, a spring 18 is interposed between the stopper
1917 and the valve element 1920, for urging the valve element 1920
toward the small pipe portion 13 (in the valve-closing
direction).
[0259] Further, the downstream end of the small pipe portion. 13 of
the cylinder 10 is provided with a guide pipe 1930 in the form of a
bottomed hollow cylinder extending downstream from the
downstream-side opening of the small pipe portion 13. The guide
pipe 1930 has its downstream end closed, and as also shown in FIG.
39A, a side wall thereof in the vicinity of the downstream end
thereof is formed with communication holes 1931 which communicate
between the inside and outside of the guide pipe 1930. Further, the
guide pipe 1930 has the valve element 1920 fitted thereon in a
manner slidable thereon, and the downstream end of the guide pipe
1930 is formed with a tapered portion 1932 the cross-section of
which decreases downstream. The tapered portion 1932 forms a valve
seat.
[0260] The valve element 1920 comprises a valve portion 1921 having
a body in the form of a stepped hollow cylinder inserted in the
cylinder 10, and a guided portion 1922 which is guided by the guide
pipe 1930 while sliding thereon, and can be held by the downstream
facing surface of a stepped portion provided at a boundary between
the small pipe portion 13 and the large pipe portion 14 of the
cylinder 10, i.e. a downstream end face 1912 of the small pipe
portion 13.
[0261] The guided portion 1922 has an upstream portion which has an
inner diameter approximately equal to the outer diameter of the
guide pipe 1930 and is slidable thereon, whereby the valve element
1920 can be stably moved forward and backward within the cylinder
10. A downstream portion of the guide pipe 1922 is slightly
increased in inner diameter to thereby form a space portion S2.
Further, as shown in FIG. 39B, a portion of the upstream end of the
guided portion 1922 is formed with a slit 1922a communicating
between the inside and outside of the guided portion 1922, whereby
the high-pressure refrigerant leaked through a gap between the
guided portion 1922 and the guide pipe 1930 can be allowed to flow
downstream.
[0262] On the other hand, the valve portion 1921 has a reduced pipe
portion 1924 extending downstream with a reduced size, and one end
of the spring 18 is fitted on the reduced pipe portion 1924. An
upstream end of the valve portion 1921 is slightly increased in
inner diameter, and the downstream end of the guided portion 1922
is press-fitted in the upstream end of the valve portion 1921.
Therefore, within the valve element 1920, there is formed a space
portion S2 defined by the valve portion 1921, the guided portion
1922, and the guide pipe 1930. The space portion S2 communicates
with the upstream side via the communication holes 1931.
[0263] Further, the tapered surface of the tapered portion 1932 of
the guide pipe 1930 and an inner peripheral edge 1924a of the
reduced pipe portion 1924 form a restriction passage. When the
valve element 1920 is held on the downstream end face 1912 of the
small pipe portion 13, the restriction passage holds the gap at a
preset value realizing the passage cross-section of the normal
restriction mechanism. However, when the valve element 1920 is
moved away from the downstream end face 1912 to be fully open, the
function of the restriction mechanism is actually terminated, but a
new refrigerant passage is formed which is increased in flow
passage area. That is, the other refrigerant passage than the
refrigerant passage that is open in the closed state of the valve
is made open in an integrating manner.
[0264] It should be noted that an adjusting mechanism, described
hereinabove, may be provided between the valve portion 1921 and the
guided portion 1922, for adjusting the positional relationship
between the valve portion 1921 and the guided portion 1922, thereby
making it possible to set the size of the restriction passage as
desired.
[0265] The stopper 1917 is equipped with an adjusting mechanism,
that is, the stopper 1917 has an outer periphery formed with an
external thread, and a downstream end of the cylinder 10 is formed
with an internal thread mating with the external thread. By
adjusting the amount of screwing of the stopper 1917 into the
cylinder 10, the position of the stopper 1917 is adjusted, whereby
the elastic force of the spring 18 can be adjusted.
[0266] Next, the pressure-cancelling structure of the expansion
device 1901 will be described,.
[0267] In the expansion device 1901, within the space portion S2,
the downstream facing surface of the guided portion 1922 forms a
valve-closing pressure-receiving surface, and on the other hand,
the upstream end of the reduced pipe portion 1924 forms a
valve-opening pressure-receiving surface which is larger in
pressure-receiving area than the valve-closing pressure receiving
surface. Further, the inner diameter of the reduced pipe portion
1924 is made smaller than that of the guided portion 1922 such that
the pressure-receiving area of the valve-opening pressure-receiving
surface becomes larger than that of the valve-closing
pressure-receiving surface. That is, the refrigerant introduced
into the space S2 acts on the valve element 1920 in the
valve-closing direction (rightward as viewed in FIG. 38A) to
thereby cancel part of the refrigerant pressure acting on the valve
element 1920 in the valve-opening direction. Therefore, the
resultant of the pressure received at the valve-closing
pressure-receiving surface and the elastic force of the spring 18
acts against the refrigerant pressure received at the valve-opening
pressure-receiving surface.
[0268] Next, the relief mechanism of the expansion device 1901 will
be described.
[0269] As shown in FIGS. 38A and 38B, in the expansion device 1901,
when the differential pressure across the expansion device 1901 has
become equal to or higher than a predetermined value to cause the
guided portion 1922 to be moved away the downstream end face 1912,
the opening area of the gap between the reduced pipe portion 1924
and the guide pipe 1930 is increased against the urging force of
the spring 19, whereby refrigerant flowing in from the upstream
side is allowed to escape at an increased flow rate. This prevents
an abnormal rise in the refrigerant pressure inside the expansion
device 1901.
[0270] FIG. 40 is an explanatory view showing the relationship
between the differential pressure across the expansion device 1901
and the opening area of the refrigerant passage(s) thereof.
[0271] As shown in FIG. 40, so long as the valve element 1920 is
held on the downstream end face 1912 of the small pipe portion 13
(state shown in FIG. 38A), even if the differential pressure rises,
the opening area is held constant by being limited by the
restriction passage. Then, when the differential pressure becomes
higher than a predetermined value, the valve element 1920 is moved
away from the downstream end face 1912 to allow refrigerant to flow
downstream at the increased flow rate. Thus, the opening area is
instantly increased (state shown in FIG. 38B). In this case, as
shown in FIG. 38B, the rate of increase in the opening area is
larger than that of the seventeenth embodiment (FIG. 35).
[0272] As described above, in the expansion device 1901 as well,
the pressure-cancelling structure and the relief mechanism function
effectively, and therefore the same advantageous effects as
provided by the first embodiment can be obtained.
[0273] Further, in the expansion device 1901 as well, similarly to
the eighteenth embodiment, when the valve element 1920 is opened,
there occurs no decrease in the effective pressure-receiving area,
which enables the balance of the pressure cancellation to be
maintained, and improves the relieving operation. Further, in
relieving the refrigerant pressure, the refrigerant passage can be
expanded instantly, which decreases the differential pressure
across the expansion device required for setting the maximum valve
lift. Therefore, the pressure load on the entire expansion device
can be reduced to thereby protect the same.
[0274] Although the preferred embodiments of the present invention
have been described heretofore, the present invention is by no
means limited to any specific one of the above-described
embodiments, but various modifications and alterations can be made
thereto without departing the spirit and scope of the present
invention.
[0275] For example, although in the above-described embodiments,
the cylinder of each expansion device is directly fixed to the
piping 50, by way of example, this is not limitative, but the
expansion device may be provided with a casing or the like which
accommodates the cylinder, and the casing or the like may be fixed
to the piping.
[0276] Further, although in the above embodiments, at least one of
the outer peripheral surface of the inner shaft member and the
inner peripheral surface of the valve element inserted therein may
be formed with at least one labyrinth groove.
[0277] It should be noted that internal components forming
expansion devices may be formed e.g. of resin.
[0278] The present invention can be applied to any expansion device
so long as it is disposed in a flow passage of refrigerant
circulating through a refrigeration cycle.
[0279] According to the expansion device of the present invention,
in the valve element, part of the refrigerant pressure is cancelled
by the pressure-cancelling structure, which makes it possible to
reduce the elastic force required of the elastic member that holds
the valve element in a manner acting against the refrigerant
pressure. As a result, it is possible to employ a small-sized
elastic member, and thereby make the configuration of the entire
expansion device compact in size.
[0280] Further, with the compact configuration, the relief
mechanism makes it possible to prevent an abnormal rise in the
refrigerant pressure inside the expansion device, to thereby
prevent breakage or the like of the internal components.
[0281] Further, by providing the relief mechanism in two stages,
i.e. as the first relief mechanism and the second relief mechanism,
refrigerant pressure reduction control can be carried out in a more
delicate manner.
[0282] The foregoing is considered as illustrative only of the
principles of the present invention. Further, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and applications shown and described, and accordingly,
all suitable modifications and equivalents may be regarded as
falling within the scope of the invention in the appended claims
and their equivalents.
* * * * *