U.S. patent application number 10/969699 was filed with the patent office on 2006-04-20 for air conditioning system expansion valve.
This patent application is currently assigned to BEHR GmbH & Co.. Invention is credited to Zhongping Zeng.
Application Number | 20060080999 10/969699 |
Document ID | / |
Family ID | 35764177 |
Filed Date | 2006-04-20 |
United States Patent
Application |
20060080999 |
Kind Code |
A1 |
Zeng; Zhongping |
April 20, 2006 |
Air conditioning system expansion valve
Abstract
The invention relates to an expansion valve, designed especially
for an air conditioning system in a motor vehicle, that comprises a
valve housing with a first high-pressure side port, a second
low-pressure side port, and a channel disposed therebetween through
which refrigerant can flow. The valve includes a sliding element
that is arranged in the channel and can move along a longitudinal
axis, wherein an aperture restricts the flow of refrigerant through
the channel, and the size and shape of the aperture is defined by
the size and shape of the sliding element and the position of the
sliding element in the channel. The expansion valve is easy to
manufacture and can be universally used based in part on the
sliding element extending completely through the channel.
Inventors: |
Zeng; Zhongping; (Okemos,
MI) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
TWO PRUDENTIAL PLAZA, SUITE 4900
180 NORTH STETSON AVENUE
CHICAGO
IL
60601-6780
US
|
Assignee: |
BEHR GmbH & Co.
Stuttgart
DE
|
Family ID: |
35764177 |
Appl. No.: |
10/969699 |
Filed: |
October 20, 2004 |
Current U.S.
Class: |
62/527 |
Current CPC
Class: |
F25B 2500/12 20130101;
F25B 41/31 20210101; F25B 2309/06 20130101; F16K 3/24 20130101;
F25B 2341/0683 20130101 |
Class at
Publication: |
062/527 |
International
Class: |
F25B 41/06 20060101
F25B041/06 |
Claims
1. An expansion valve, especially for an air conditioning system of
a motor vehicle, comprising: a valve housing that includes a first
port and a second port and a first refrigerant channel disposed
between the first and second ports; and a sliding valve element
that is capable of movement that defines a stroke along a
longitudinal axis, wherein the position of the valve element along
its stroke determines the amount of refrigerant that may flow in
the channel and wherein the sliding element completely extends
through the channel throughout its stroke.
2. An expansion valve according to claim 1, wherein the valve
element is disposed in a hole that crosses the refrigerant
channel.
3. An expansion valve according to claim 1, wherein the valve
element comprises an elongated body that includes an end section of
a constant cross-section and a directly adjacent control section
with a tapered cross-section.
4. An expansion valve according to claim 3, wherein the control
section of the valve element includes a cross-section that changes
over its length.
5. An expansion valve according to claims 3, wherein the diameter
of end section of the valve element is larger than the diameter of
the first refrigerant channel.
6. An expansion valve according to claim 1, wherein a control
mechanism determines the position of the valve element in its
stroke.
7. An expansion valve according to claim 6, wherein the control
mechanism includes a spring that exerts a force upon the valve
element.
8. An expansion valve according to claim 7, wherein the spring and
the control mechanism are disposed on the same side of the first
refrigerant channel.
9. An expansion valve according to claims 6, wherein the control
mechanism includes a pressure-loaded membrane.
10. An expansion valve according to claim 9, wherein the valve
housing further includes a third port.
11. An expansion valve according to claim 10, wherein the valve
housing further includes a fourth port and a second refrigerant
channel disposed between the third and fourth ports.
12. An expansion valve according to claim 10, wherein the pressure
of refrigerant available at the third port exerts a force upon the
membrane.
13. An expansion valve according to claim 10, wherein a closed
volume exerts pressure upon the membrane and wherein the volume is
in thermal contact with refrigerant available at the third
port.
14. An expansion valve according to claim 10, wherein the pressure
of refrigerant in a refrigerant channel exerts a force upon the
membrane.
15. An expansion valve according to claim 10, wherein the initial
position of the valve element is determined by position of the
control mechanism in relation to the valve housing.
Description
FIELD OF THE INVENTION
[0001] The invention generally relates to an expansion valve that
may be used in an air conditioning system, including an automobile
air conditioning system, and methods of use therefor.
BACKGROUND OF THE INVENTION
[0002] Modern air conditioning systems often use a controllable
expansion valve to regulate the mass flow rate of an expanding
refrigerant. This type of expansion valve typically can be set to
two positions, i.e., to a closed or open state, depending on an
operating parameter of the air conditioning system. The proper
operation of the valve helps to insure that the refrigerant super
heats before entering the compressor so that the efficiency of the
air conditioning system is maintained within an optimal range. A
properly operating expansion valve may reduce the need for a
low-pressure collector to protect the compressor from fluid
refrigerant entering the compressor.
[0003] EP 1 001 229 A2 (see also U.S. Pat. No. 6,430,950) describes
an expansion valve for an air conditioning system of a motor
vehicle in which a sliding needle plunges essentially vertically
into an expansion channel, which channel separates the
high-pressure side from the low-pressure side of the refrigerant
cycle. The cross-section of the channel is partially free, because
the sliding needle only partially plunges into the channel. When
the needle completely penetrates the channel, the valve is closed.
The valve is opened at a maximum when the sliding needle does not
extend into the channel at all.
[0004] Prior art expansion valves, however, are difficult to
manufacture and/or are limited in applicability. In addition, the
desirable operating range of prior art expansion valves can be
difficult to set.
SUMMARY OF THE INVENTION
[0005] The invention provides an improved expansion valve for use
in a refrigeration circuit that is easy to manufacture and can be
in a wide variety of applications.
[0006] In preferred embodiment of the invention, a sliding element
is fully inserted in a channel at any state of the expansion valve,
and the mass flow rate through the valve is dependent on the shape
of the sliding element. Due to the resulting flow along the shape
of the sliding element, the desirable flow characteristics of the
refrigerant in the channel aperture are improved, which
correspondingly reduces the noise level caused by the valve.
[0007] An advantage of a valve made according to the invention is
that the sliding element, which may include a control section, is
located properly and accurately in every position. In addition, the
shaping of the control section allows accurate set up of the valve
aperture in dependence on the position of the sliding element. The
sliding element may be shaped as an elongated body with a constant
cross-section at one end and an adjacent control section that,
compared to the end section, has a tapered cross-section. The
sliding element and an associated control section further may be
advantageously placed in a slot (or in a zone near the slot) in the
channel that permits the passage of refrigerant from an area of
relatively higher pressure to an area of relatively lower pressure.
The tapering of the control section of the sliding element may be
of a constant diameter so that the change of the aperture in
dependence on the motion of the sliding element is constant.
However, depending on the technical requirements of each system,
the tapering may also have a variable cross-section so that the
aforementioned dependence is not constant. This design allows for a
precise optimization of the function of the expansion valve
according to the invention, which can improve the efficiency and
the reliability of an air conditioning system. In addition, it is
possible, as regards the usability of the expansion valve in air
conditioning systems of various types and sizes, to provide a
channel and slot for a sliding element of a sufficiently large
diameter, and further to adjust or adapt the dimensions of the
tapering in the zone of the control section to a particular type of
air conditioning system.
[0008] In order to achieve an acceptable seal between the channel
and sliding element, the diameter of the sliding element at the end
can be larger than the width of flanges that define a sealable
opening into the channel. This design enlarges the sealing surface
between the channel wall and the sliding element in various states
of the sliding element. It also will be appreciated by persons of
skill in the art that the diameter of the channel may be larger,
smaller or the same size as the diameter of the sliding element or
the aperture into which the sliding element is placed.
[0009] Furthermore, the sliding element may be advantageously
shifted by means of a control mechanism in the direction of the
axis, whereby the valve is made settable. In an especially
advantageous design, the control mechanism includes a spring to
bias the position of the sliding element. This spring force defines
in a simple fashion, a mechanical condition for the opening of the
valve. In order to ensure that the construction of the expansion
valve is simple and cost-effective, the spring and the control
mechanism may be arranged on the same side as the sliding
element.
[0010] A control mechanism associated with the valve may further
include a pressurized membrane. The membrane, which is mechanically
connected to the sliding element, allows for a simple motion of the
sliding element in dependence on the operating parameters of the
air conditioning system.
[0011] In a preferred embodiment, there is a third low-pressure
connection for the refrigerant to the valve housing. A membrane of
the control mechanism may be exposed to the pressure or temperature
of the refrigerant, and particularly to the pressure or temperature
in the suction line before the compressor. This design makes it
possible to control, in a simple fashion, the sliding element in
dependence on a parameter of the refrigerant's state after its
expansion.
[0012] In a further preferred embodiment, there is a fourth
low-pressure connection for the refrigerant to the valve housing.
Refrigerant flows through the third connection into the valve,
without any substantial loss of pressure, and then flows out of the
valve through the fourth connection so that the valve housing also
forms a part of a low-pressure line of the refrigerant cycle. An
expansion valve made according to the invention may be used in a
closed volume system, wherein pressure in the system exerts
pressure upon the membrane, and wherein the volume is in thermal
contact with the third connection. In this manner, the temperature
of the refrigerant, which is adjacent to the third connection, can
be directly converted, in a mechanical electromechanical fashion,
into a corresponding activation/triggering of the sliding element.
This conversion occurs in an especially efficient manner if the
volume is filled with a defined quantity of a suitable substance,
of, for example, the refrigerant of the air conditioning
system.
[0013] As an alternative to exerting pressure upon the membrane
from a closed volume, the membrane can also be exposed to a force
exerted by the air conditioning system's refrigerant's pressure,
and particularly to a refrigerant under high pressure. Such a
design of the control mechanism can be particularly advantageous in
the case of CO.sub.2 air conditioning systems, which--compared to
conventional air conditioning systems--have somewhat significantly
different operation parameters.
[0014] In the interest of a simple construction and reduction of
the number of components, the sliding element may be set to a
default setting by positioning the control mechanism in a
particular relation to the valve housing. In this arrangement there
is no need for any additional adjustment of screws, and only the
attachment and sealing of the control mechanism in relation to the
valve housing requires special design attention.
[0015] Further advantages and features of the expansion valve as
designed by this invention become apparent from the subsequent
design example and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a side view of a cross-section of an expansion
valve of the invention.
[0017] FIG. 2 is an exploded view of region A of FIG. 1.
[0018] FIG. 3 is a top view of a cross-section through the
expansion valve from FIG. 1 along the line B-B in the closed state
of the valve.
[0019] FIG. 4 is a top view of a cross-section through the
expansion valve from FIG. 1 along the line B-B in an at least
partially open state of the valve.
[0020] FIG. 5 is a top view of an alternative embodiment of the
cross-section through the expansion valve from FIG. 1 along the
line B-B in the closed state of the valve.
DETAILED DESCRIPTION OF THE INVENTION
[0021] FIG. 1 illustrates an expansion valve in accordance with the
invention. This valve includes a valve housing 1, which may consist
of several components in order to simplify its assembly.
[0022] A zone of the valve housing, shown at the lower section of
the housing 1 in FIG. 1, includes a first port 2 and a second port
3, which in a preferred embodiment may be located at the same
height and preferably in the same axis. The first port 2 is
connected with a refrigerant line that comes from the condenser of
the refrigeration circuit, and, in general, is part of the
high-pressure section of the refrigeration circuit. The second port
3 is part of the low-pressure section of the refrigeration circuit,
which, in FIG. 1, is also illustrated by means of a larger
diameter.
[0023] In a preferred embodiment, ports 2 and 3 are connected
through an expansion element of the air conditioning system in
which previously compressed refrigerant expands and cools. The
expansion element includes a channel 4, which connects ports 2 and
3, wherein the common axis of ports 2 and 3 is also the middle axis
of channel 4.
[0024] As illustrated in FIG. 1, channel 4 is intersected by a hole
5 that is vertical to the axis of the channel, and in which is
disposed a sliding element 6. Sliding element 6 is shaped as an
elongated body and may travel along an axis within hole 5. The hole
5 extends on both sides of the channel 4, and a downward-leading
part of the hole is designed as a blind hole 5a in the valve
housing 1. Channel 4 may have a constant or varying diameter. In
addition, the diameter of channel 4 at the intersection of hole 5
may be larger, smaller or the same size as hole 5.
[0025] As illustrated in FIG. 2, the sliding element 6 comprises a
lower end section 6a, which is formed as a dimensionally accurate
cylinder. In a preferred embodiment of the invention, the end
section 6a is coupled to a rotationally symmetrical control section
6b of the sliding element 6 that is concentric to the end section
6a. The diameter of the control section 6b is conically tapered and
has a cross-section that is smaller than the cross-section of the
end section 6a. Overall, the control section forms a rotationally
symmetrical truncated cone. The control section 6b may have other
shapes and forms, and can also be shaped, for example, as a
cylindrical body with an aperture.
[0026] The control section 6b is coupled to a cylindrical shaft 6c
of the sliding element 6, which, in the example of FIG. 2, has the
same diameter as the lower end section. It is noted, however, that
the diameters of these shafts may differ depending on the desired
characteristics.
[0027] FIGS. 3 and 4 illustrate the sliding element 6 in different
operating positions. As is apparent from these figures, the
movement of the sliding element along its longitudinal axis sets up
a variable aperture 14 of the channel 4.
[0028] As illustrated in FIG. 3, in the uppermost shifted position
of the sliding element, the end section 6a is completely inserted
into channel 4. As one of ordinary skill in the art will
appreciate, the dimensions of the components are selected (for
example, by finely grinding the hole 5 and the end section 6a) such
that a sealing closure, at least in the sense of the function of
the air conditioning system is established. A complete hermetic
sealing in the strict sense of the term is usually not required,
however. In order to achieve an appropriate seal, the diameter of
the end section 6a may be noticeably larger than the diameter of
the channel 4, which creates a particularly large contact surface.
An end section 6a is arranged only between two flanges 4a located
in the channel 4, which also achieves a sufficient seal. In the
design of a preferred embodiment, the flanges 4a or another insert
formed differently but having the same function in the channel 4
can be made of a material with the same properties of thermal
expansion as the sliding element 6.
[0029] FIG. 5 illustrates an alternative structure of lower end
section 6a. In this embodiment, a portion of lower end section 6a
has been machined to a flat shape, as indicated by reference number
6d. This structure permits displacement of any fluid or material
captured in blind hole 5a as sliding element moves into blind hole
5a. In an embodiment of the invention, the width of the
non-circular feature 6d is less than the width of the flanges 4a in
order to reduce the possibility of leakage, as the rotational
orientation of the sliding element 6 with respect to channel 4 may
change over time.
[0030] If, starting from its closed position (see FIG. 3), the
sliding element 6 is moved downward as shown in FIG. 1, the control
section 6b crosses the channel 4. The end section 6a plunges into
the blind-hole zone 5a of the hole 5. In this arrangement, the
channel 4 is completely penetrated by the sliding element 6
regardless of the operating conditions of the expansion valve. The
tapering of the control section creates an aperture 14, which
varies depending on the position of the sliding element. In the
area of the aperture, the refrigerant expands in a controlled
fashion and flows along the outer circumference of the control
section 6b of the sliding element 6 in a plane that is essentially
vertical to the longitudinal axis of the sliding element 6. In FIG.
4, the flowing of the refrigerant is indicated by means of arrows.
Overall, this process results in the low-noise expansion of the
refrigerant.
[0031] Due to the conical tapering of the control section 6b, the
aperture 14 is not enlarged in a linear relation to the
longitudinal motion of the sliding element 6, but--as, for example,
in a preferred embodiment as illustrated in FIGS. 1-4--in an
essentially quadratic relation. Thus, the mass flow of refrigerant
does not always depend on an operation parameter in a linear
manner. In general, a suitable shaping of the control section 6
allows for the accurate adjustment of an expansion valve to a
control parameter.
[0032] The shaft 6c of the sliding element passes through various
portions of valve housing 1. A sealing element 7 seals shaft 6c at
the point of penetration of control channel 8. An o-ring completely
surrounds and seals the shaft 6 from control channel 8. In this
manner, the contact surface between the shaft 6c and the wall of
hole 5 can be pressure-sealed from control channel 8.
[0033] Control channel 8 extends through valve housing 1 and is
separate from channel 4 in a preferred embodiment. It is also
possible, however, that channel 8 may be more directly coupled to
channel 4. In the embodiment illustrated in FIG. 1, channel 8
includes a third port 8a and a fourth port 8b. The third port 8a is
connected to an outlet of an evaporator of the refrigerant circuit,
and the fourth port 8b is connected to the suction inlet of a
compressor of the refrigerant circuit. Thus, in relation to the
circuit, the refrigerant--when flowing through the control channel
8--is in its lowest pressure zone, which is also reflected in the
larger diameter of ports 8a and 8b as compared to those of ports 2
and 3.
[0034] Shaft 6c crosses the control channel 8 and terminates in a
plunger 6d of the sliding element 6. Plunger 6d passes through a
hole in the housing area 1a. An upper end surface of the plunger 6d
is, at least in one direction, in a non-positive connection with
the membrane 9. The membrane 9 is held in a housing 10, wherein an
upper part of membrane housing 10 and the side of the membrane
opposite the membrane's connection with the plunger 9 hermetically
close off a volume 11. Inside membrane housing 10 is a sealing plug
12, by means of which the volume 11 can be filled with a defined
quantity of a substance under certain defined conditions, e.g.,
pressure or temperature. A collar 10a of the membrane housing is
held, by means of a thread, in the hole through the valve housing
1a, and sealing means (not shown) ensure that the control channel 8
is sealed. The plunger 6d longitudinally slides along an internal
side of the collar 10a.
[0035] The plunger assembly may be screwed into place, within a
tolerance range, of different depths and in a sealing connection,
which allows the depth at which the sliding element 6 plunges into
the hole to be pre-set. This arrangement compensates for the
tolerances in the manufacture of individual components.
[0036] Sliding element 6 is also supported against the lower side
of the control channel 8 by means of a helical spring 13, wherein
the helical spring 13 envelops the shaft 6c and rests against the
plunger 6d. The sliding element is thus biased in a direction of
the spring force.
[0037] Spring 13, membrane 9, membrane housing 10, and enclosed
volume 11 form a control mechanism, by means of which the sliding
element 6 is moved, in a controlled manner, in dependence on the
operation parameters of the air conditioning system. In this
configuration, three forces act upon the sliding element, i.e., the
pressure force of the refrigerant in the control channel 8, the
spring force of spring 13, and the pressure force exerted by the
volume 11. The substance contained in volume 11 exerts a force on
membrane 9 and acts in a direction opposite to the two other
forces. Thus, in the direction of its longitudinal axis, the
position of sliding element will be determined by the interaction
of these forces. The pressure force of the refrigerant in channel 4
acting on the sliding element is limited because at that location,
the sliding element 6 has a relatively small cross-section.
[0038] Through the surface of membrane 9 and the interstice between
the plunger 6d and the collar 10a, volume 11 is in thermal contact
with the refrigerant of the control channel 8. A decrease in the
pressure of the refrigerant in control channel 8 (typically, after
an evaporator) and an increase in the temperature of the
refrigerant in the control channel 8 result in a net increase of
the force component acting against the opposing forces in a
direction of the spring force. The sliding element 6, therefore,
moves downward in the opening direction. In contrast, a decrease in
the temperature in the zone of the control channel 8 results in the
aperture 14 being closed. A reduced mass flow of the refrigerant in
the evaporator then causes an increase in the temperature of the
refrigerant in the control channel 8 and/or in the suction line of
the compressor. In this manner, a mechanical control circuit
arises, which--after a proper pre-alignment and setting of the
control mechanism--ensures that the refrigerant sufficiently
superheats after the evaporator. This results in a good efficiency
of the air conditioning system and reduces the possibility that
condensed refrigerant will enter the compressor.
[0039] It is a matter of course that the properties of the
expansion valve as designed by this invention are not restricted to
the embodiments as illustrated and described above. The control of
the sliding element can be realized in any known form including a
purely electromechanical control in conjunction with an electronic
control device.
[0040] While the invention has been described with an emphasis upon
particular embodiments, it should be understood that the foregoing
description has been limited to the presently contemplated best
mode for practicing the invention. It will be apparent that various
modifications may be made to the invention, and that some or all of
the advantages of the invention may be obtained. Also, the
invention is not intended to require each of the above-described
features and aspects or combinations thereof. In many instances,
certain features and aspects are not essential for practicing other
features and aspects. The invention should only be limited by the
appended claims and equivalents thereof, since the claims are
intended to cover other variations and modifications even though
not within their literal scope.
* * * * *