U.S. patent application number 09/878961 was filed with the patent office on 2001-10-11 for capacity-controlled scroll-type compressor having internally-bypassing system.
This patent application is currently assigned to MITSUBISHI HEAVY INDUSTRIES, LTD.. Invention is credited to Kawada, Minoru, Yuzaki, Tsuneo.
Application Number | 20010028852 09/878961 |
Document ID | / |
Family ID | 27341689 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010028852 |
Kind Code |
A1 |
Yuzaki, Tsuneo ; et
al. |
October 11, 2001 |
Capacity-controlled scroll-type compressor having
internally-bypassing system
Abstract
A capacity-controlled scroll-type compressor having an
internally-bypassing system is provided, by which when the capacity
is controlled, it is possible to prevent the tip gaps near the
gas-suction inlet or the main stream of a bypassing gas from
becoming smaller than those of other portions. Regarding the tip
gaps near the gas-suction inlet, the length of teeth of a portion
of the scrolls, which is closer to the gas-suction inlet, is
shorter than teeth of other portions of the scrolls. Regarding the
tip gaps near the main stream of a bypassing gas, (i) the length of
teeth of a portion of the scrolls, which is close to the main
stream of a bypassing gas, is shorter than teeth of other portions,
or (ii) a gas-suction inlet is positioned near the main stream of a
bypassing gas so as to suppress increase in the temperature of an
area neighboring the main stream of the bypassing gas.
Inventors: |
Yuzaki, Tsuneo;
(Nishi-kasugai-gun, JP) ; Kawada, Minoru;
(Nishi-kasugai-gun, JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
MITSUBISHI HEAVY INDUSTRIES,
LTD.
Tokyo
JP
|
Family ID: |
27341689 |
Appl. No.: |
09/878961 |
Filed: |
June 13, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09878961 |
Jun 13, 2001 |
|
|
|
09212861 |
Dec 17, 1998 |
|
|
|
Current U.S.
Class: |
417/310 |
Current CPC
Class: |
F04C 28/12 20130101;
F04C 18/0269 20130101 |
Class at
Publication: |
417/310 |
International
Class: |
F04B 049/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 18, 1997 |
JP |
9-363832 |
Dec 18, 1997 |
JP |
9-363833 |
Dec 18, 1997 |
JP |
9-363834 |
Claims
What is claimed is:
1. A capacity-controlled scroll-type compressor having an
internally-bypassing system, the compressor comprising a housing,
scrolls, and a gas-suction inlet, wherein: the gas-suction inlet is
positioned at the low-pressure side inside the housing; and the
length of teeth of a portion of the scrolls, which is closer to the
gas-suction inlet, is shorter than teeth of other portions of the
scrolls.
2. A capacity-controlled scroll-type compressor having an
internally-bypassing system, the compressor comprising scrolls,
wherein: the length of teeth of a portion of the scrolls, which is
close to the main stream of a bypassing gas, is shorter than teeth
of other portions.
3. A capacity-controlled scroll-type compressor as claimed in claim
1, wherein the target portion for shortening the teeth is of a
hardening-processed scroll of the above scrolls.
4. A capacity-controlled scroll-type compressor as claimed in claim
2, wherein the target portion for shortening the teeth is of a
hardening-processed scroll of the above scrolls.
5. A capacity-controlled scroll-type compressor having an
internally-bypassing system, the compressor comprising a
gas-suction inlet positioned near the main stream of a bypassing
gas so as to suppress increase in the temperature of an
area-neighboring the main stream of the bypassing gas.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a capacity-controlled
scroll-type compressor having an internally-bypassing system.
[0003] This application is based on Patent Applications Nos. Hei
9-363832, Hei 9-363833, and Hei 9-363834 filed in Japan, the
contents of which are incorporated herein by reference.
[0004] 2. Description of the Related Art
[0005] In conventional capacity-controlled scroll-type compressors
having an internally-bypassing system, when the capacity of the
compressor is controlled, a temperature difference occurs between
an area through which higher-temperature bypassing gas passes and
another area through which lower-temperature suction gas passes.
Therefore, a gap at a tip provided on the head of each tooth near a
gas-suction inlet tends to decrease and thus scuffing occurs.
[0006] On the other hand, when the capacity of the compressor is
controlled, the temperature of a portion of scrolls, which is close
to the main stream of higher-temperature bypassing gas, is higher
than the temperature of other portions. Therefore, the teeth of the
higher-temperature portion is extended, thereby decreasing a gap at
a tip of the teeth and also generating scuffing in this case.
SUMMARY OF THE INVENTION
[0007] An object of the present invention is to solve the above
problem related to scuffing due to decrease of such a tip gap.
[0008] Therefore, the present invention provides a
capacity-controlled scroll-type compressor having an
internally-bypassing system, the compressor comprising a housing,
scrolls, and a gas-suction inlet, wherein the gas-suction inlet is
positioned at the low-pressure side inside the housing; and the
length of teeth of a portion of the scrolls, which is closer to the
gas-suction inlet, is shorter than teeth of other portions of the
scrolls.
[0009] According to this structure, when the capacity is
controlled, it is possible to prevent the tip gaps near the
gas-suction inlet from becoming smaller than those of other
portions; thus, scuffing can be prevented between the heads of the
target spiral lap and the inner surface of an end plate in the
compressor.
[0010] The present invention also provides a capacity-controlled
scroll-type compressor having an internally-bypassing system, the
compressor comprising scrolls, wherein the length of teeth of a
portion of the scrolls, which is close to the main stream of a
bypassing gas, is shorter than teeth of other portions.
[0011] According to this structure, when the capacity is
controlled, it is possible to prevent the tip gaps near the main
stream of a bypassing gas from becoming smaller than those of other
portions; thus, scuffing can be prevented between the heads of the
target spiral lap and the inner surface of an end plate in the
compressor.
[0012] In the above structures, the target portion for shortening
the teeth may be of a hardening-processed scroll of the above
scrolls.
[0013] The present invention also provides a capacity-controlled
scroll-type compressor having an internally-bypassing system, the
compressor comprising a gas-suction inlet positioned near the main
stream of a bypassing gas so as to suppress increase in the
temperature of an area neighboring the main stream of the bypassing
gas.
[0014] Also in this arrangement, when the capacity is controlled,
it is possible to prevent the tip gaps near the main stream of a
bypassing gas from becoming smaller than those of other portions;
thus, scuffing can be prevented between the heads of the target
spiral lap and the inner surface of an end plate in the
compressor.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a sectional view in the longitudinal direction,
showing a scroll-type compressor as the first embodiment according
to the present invention.
[0016] FIG. 2 is a sectional view along line "B-B" in FIG. 1.
[0017] FIG. 3 is a sectional view along line "C-C" in FIG. 1.
[0018] FIG. 4 is a sectional view in the longitudinal direction,
showing a scroll-type compressor as the second embodiment according
to the present invention.
[0019] FIG. 5 is a sectional view along line "B-B" in FIG. 4.
[0020] FIG. 6 is a sectional view along line "C-C" in FIG. 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] The first embodiment of the present invention is shown in
FIGS. 1-3. FIG. 1 is a sectional view in the longitudinal
direction, FIG. 2 is a sectional view along line "B-B" in FIG. 1,
and FIG. 3 is a sectional view along line "C-C" in FIG. 1.
[0022] In FIG. 1, reference numeral 1 indicates a housing which
comprises cup-like main body 2, and front housing 6 fastened to the
body 2 using a bolt (not shown). Rotational shaft 7 is supported by
the front housing 6 via bearings 8 and 9, in a freely rotatable
relationship.
[0023] Fixed scroll 10, revolving scroll 14, and capacity-control
block 50 are provided inside the housing 1. This fixed scroll 10
comprises end plate 11 and spiral lap 12 disposed on inner surface
11a of the plate 11, and the surface faces end plate 15. The
revolving scroll 14 comprises the end plate 15 and spiral lap 16
which is disposed on inner surface 15a of the plate 15, and the
surface faces the end plate 11.
[0024] Inside projecting disk-shaped boss 20, provided at a center
area in the outer surface (opposite to inner surface 15a) of end
plate 15 of revolving scroll 14, drive bush 21 is inserted in a
freely rotatable state via revolving bearing 23. Slide hole 24 is
provided in the drive bush 21, and eccentric drive pin 25 is
inserted into the slide hole 24 so as to perform a freely-sliding
motion of the pin. The projecting drive pin 25 is eccentrically
provided on an end face of larger-diameter portion 7a of rotational
shaft 7, the portion 7a being provided on an end of the main body 2
side of the rotational shaft 7.
[0025] The axes of the revolving and fixed scrolls 14 and 10 are
separated from each other by a predetermined distance, that is,
they are in an eccentric relationship, as shown in FIG. 2. In
addition, the phases of these scrolls differ by 180.degree., and
they are engaged with each other.
[0026] Accordingly, as shown in FIG. 1, tip seals 17, provided and
buried at each head surface of spiral lap 12, are in close contact
with surface 15a of end plate 15, while tip seals 18, provided and
buried at each head surface of spiral lap 16, are in close contact
with surface 11a of end plate 11. The side faces of spiral laps 12
and 16 make linear contact at plural positions and thus plural
compression chambers 19a and 19b are formed essentially at
positions of point symmetry with respect to the center of the
spiral, as shown in FIG. 2.
[0027] Also as shown in FIG. 2, a central part of end plate 11 is
bored to provide discharge port 29, and a pair of bypassing ports
33a and 33b, joined with compression chambers 19a and 19b during
compression, are provided.
[0028] In addition, the capacity-control block 50 is arranged in a
manner such that this block is in close contact with the outer
surface of end plate 11, thereby limiting concave areas 87 and 88.
The head of screwing bolt 13 which passes through the
capacity-control block 50 and the cup-like main body 2 is inserted
into end plate 11 of the fixed scroll 10, thereby fastening the
fixed scroll 10 and the capacity-control block 50 to the cup-like
main body 2.
[0029] The outer-peripheral surface of flange 51 arranged at the
outer end of the capacity-control block 50 is in close contact with
the inner surface of the cup-like main body 2, thereby dividing the
inside of housing 1 into plural chambers. That is, discharge cavity
31 is limited at the outside of flange 51, while low-pressure
chamber 28 is limited at the inside of the flange 51.
[0030] As shown in FIG. 3, at a central area of capacity-control
block 50, discharge hole 53 joined with discharge port 29 is
provided, and opening/closing operations of this hole 53 is
performed using discharge valve 30 which is attached to the outer
surface of capacity-control block 50 via bolt 36.
[0031] Cylinder 54 like a blind opening is provided at one side of
discharge hole 53, and blind opening 55 is provided at the other
side, in parallel with the cylinder 54.
[0032] By inserting cup-like piston 56 into cylinder 54 in a closed
and freely-sliding state, control pressure chamber 80 is limited at
the side of the inner end of piston 56 while chamber 81 is limited
at the other side. This chamber 81 is joined with suction chamber
28.
[0033] In cylinder 54, connection hole 92 joined with discharge
hole 53 and connection hole 89 joined with concave area 88 are
provided.
[0034] The piston 56 is forced toward control pressure chamber 80
by coil spring 83 which is inserted between the piston and spring
bearing 82.
[0035] A circular groove 93, arranged along the outer-peripheral
surface of piston 56, is linked with chamber 81 via plural holes 94
in any operational state.
[0036] On the other hand, control valve 58 is inserted into the
opening 55. This control valve 58 senses a high pressure inside the
discharge cavity 31 and a low pressure inside the low-pressure
chamber 28, and generates a control pressure in accordance with the
sensed pressure.
[0037] As shown in FIG. 1, between the peripheral edge of the outer
surface of end plate 15 of revolving scroll 14 and an inner end
face of front housing 6, thrust bearing 36 and Oldham link 26 are
inserted.
[0038] In order to balance a dynamically unbalanced situation due
to a revolving motion of the revolving scroll 14, balance weight 27
is attached to drive bush 21, and balance weight 37 is attached to
the rotational shaft 7.
[0039] In addition, piping fitting 40 is fastened to an upper
portion of cup-like main body 2 via bolt 41, and gas-suction path
42 and gas-discharge path 43 are limited between the piping fitting
40 and the outer-peripheral surface at the upper side of the
cup-like main body 2.
[0040] This gas-suction path 42 is joined with low-pressure chamber
28 via gas-suction inlet 44, and the gas-discharge path 43 is
joined with the discharge cavity 31 via hole 45.
[0041] Accordingly, at the time of a full-loading operation of the
compressor, when the rotational shaft 7 is rotated, revolving
scroll 14 is driven via eccentric drive pin 25, slide hole 24,
drive bush 21, revolving bearing 23, and boss 20. The revolving
scroll 14 revolves along a circular orbit, while rotation of the
scroll 14 is prohibited by the Oldham link 26.
[0042] In this way, the line-contact portions in the side faces of
spiral laps 12 and 16 gradually move toward the center of the
"swirl", and thereby compression chambers 19a and 19b also move
toward the center of the swirl while the volume of each chamber is
gradually reduced.
[0043] Accordingly, gas, which has flowed into low-pressure chamber
28 through gas-suction path 42 and gas-suction inlet 44, enters
from an opening which is limited by the outer peripheral edges of
spiral laps 12 and 16 to compression chambers 19a and 19b. This gas
is gradually compressed and reaches central chamber 22. From the
central chamber, the gas passes through discharge port 29 and
discharge hole 53, and presses and opens discharge valve 30, and
thereby the gas is discharged into discharge cavity 31. The gas is
then discharged outside via hole 45 and gas-discharge path 43.
[0044] At the time of a non-loading operation of the compressor, a
low pressure for control is generated via the control valve 58.
When this control pressure is introduced into control pressure
chamber 80, piston 56 receives the restoring force of coil spring
83 and is forced and positioned as shown in FIG. 1.
[0045] In this way, gas during compression in compression chambers
19a and 19b is introduced via bypassing ports 33a and 33b, concave
areas 87 and 88, and connection hole 89, into chamber 81. On the
other hand, the gas after compression is introduced from central
chamber 22 via discharge port 29, discharge hole 53, connection
hole 92, groove 93, and holes 94, into the chamber 81. Both flows
of gas meet in chamber 81, and merged gas flows through groove 84,
formed by cutting a portion of the outer peripheral surface of end
plate 11 of the fixed scroll 10, into low-pressure chamber 28.
[0046] At the time of a full-loading operation of the compressor, a
high pressure for control is generated using control valve 58. When
this control pressure is introduced into the control chamber 80,
piston 56 moves back against the impact-resilience force of coil
spring 83 and the outer end of the piston comes into contact with
spring bearing 82. Accordingly, both connection holes 89 and 92 are
closed by piston 56.
[0047] On the other hand, when in an operation mode for controlling
(or reducing) capacity, a control pressure corresponding to a
desired reducing ratio is generated using control valve 58. When
this control pressure acts on the inner end face of piston 56 via
control chamber 80, piston 56 is positioned where the pressing
force due to the control pressure and the impact-resilience force
by the coil spring 83 are balanced, Therefore, under conditions of
lower control pressure, only connection hole 89 is open, and a
portion of the gas during compression in compression chambers 19a
and 19b is discharged into low-pressure chamber 28 according to the
degree of opening of the connection hole 89.
[0048] In addition, the connection hole 92 is gradually opened in
accordance with increase of the control pressure. The degree of
opening of the hole 92 is thus increased, and when the hole 92 is
fully opened, the capacity of the compressor becomes zero.
[0049] At the time of a non-loading operation of the compressor,
that is, when the capacity is controlled, a high-temperature
bypassing gas flows through chamber 81 of cylinder 56 into
low-pressure chamber 28. Therefore, the temperature of an area
neighboring the main stream of the bypassing gas, that is, the
temperature of a lower portion of the cup-like main body 2, is
increased, while the low temperature of an area neighboring the
gas-suction inlet 44, into which low-temperature suction gas flows,
that is, the temperature of an upper portion of the cup-like main
body 2, is maintained. Therefore, a temperature difference occurs
in the cup-like main body 2, and accordingly, a difference of
thermal expansion occurs.
[0050] Here, the fixed scroll 10 is fixed to the cup-like main body
2. Therefore, if a thermal-expansion difference occurs there, the
gap between the head of a portion of spiral lap 12 near the
gas-suction inlet 44 and the inner surface 15a of end plate 15, and
also the gap between the head of a portion of spiral lap 16 near
the gas-suction inlet 44 and the inner surface 11a of end plate 11,
that is, "tip gaps" of such portions become smaller than those of
other portions.
[0051] Therefore, in the present invention, the length (of the
teeth) of such a portion of spiral lap 12 of fixed scroll 10 and/or
the length (of the teeth) of such a portion of spiral lap 16 of
revolving scroll 14 positioned near the gas-suction inlet 44 are
shorter than those of other portions by approximately 20 pm. This
setting is suitably performed within approximately 900.
[0052] Accordingly, when the capacity is controlled, it is possible
to prevent the tip gaps near the gas-suction inlet 44 from becoming
smaller than those of other portions; thus, scuffing can be
prevented between the head of spiral lap 12 and the inner surface
15a of end plate 15, and also between the head spiral lap 16 and
the inner surface 11a of end plate 11.
[0053] Also when the capacity is controlled and a high-temperature
bypassing gas flows through chamber 81 of cylinder 56 into
low-pressure chamber 28, the temperature of portions of spiral laps
near the flow of bypassing gas is increased and the portions
thermally expand. Accordingly, the gap between the head of a
portion of spiral lap 12 near the gas-suction inlet 44 and the
inner surface 15a of end plate 15, and also the gap between the
head of a portion of spiral lap 16 near the gas-suction inlet 44
and the inner surface 11a of end plate 11, that is, "tip gaps" of
such portions become smaller than those of other portions.
[0054] Therefore, also regarding these portions, the length (of the
teeth) of such a portion of spiral lap 12 of fixed scroll 10 and/or
the length (of the teeth) of such a portion of spiral lap 16 of
revolving scroll 14 positioned near the main stream of the
bypassing gas are shorter than those of other portions by
approximately 20 .mu.m. This setting is suitably performed within
approximately 90.degree..
[0055] Accordingly, when the capacity is controlled, it is possible
to prevent the tip gaps near the main stream of the bypassing gas
from becoming smaller than those of other portions; thus, scuffing
can be prevented between the head of spiral lap 12 and the inner
surface 15a of end plate 15, and also between the head spiral lap
16 and the inner surface 11a of end plate 11.
[0056] Preferably, regarding the above two cases, in order to
realize necessary dimensional tolerance, if the inner surface of
the end plate of one of the fixed and revolving scrolls 10 and 14,
and the outer surface of the relevant spiral lap are subjected to a
surface-hardening process, the target teeth of the surface-hardened
spiral lap are made shorter.
[0057] The second embodiment of the present invention is shown in
FIGS. 4-6. FIG. 4 is a sectional view in the longitudinal
direction, FIG. 5 is a sectional view along line "B-B" in FIG. 4,
and FIG. 6 is a sectional view along line "C-C" in FIG. 4.
[0058] The second embodiment has an arrangement similar to that of
the first embodiment except for positions of gas-suction inlet 44
and relevant elements joined or connected therewith. In FIGS. 4-6,
parts which are identical or have identical functions to those
shown in FIG. 1-3 are given identical reference numbers.
[0059] In the present embodiment, piping fitting 40 is fastened to
a lower portion of cup-like main body 2 via bolt 41, and
gas-suction path 42 and gas-discharge path 43 are limited between
the piping fitting 40 and the outer-peripheral surface at the lower
side of the cup-like main body 2.
[0060] Therefore, at the time of a non-loading operation of the
compressor, a low pressure for control is generated via the control
valve 58. When this control pressure is introduced into control
pressure chamber 80, piston 56 receives the restoring force of coil
spring 83 and is forced and positioned as shown in FIG. 4.
[0061] Full-loading and non-loading operations of the compressor in
the present embodiment are similar to those of the first
embodiment.
[0062] Here, when the capacity is controlled, a high-temperature
bypassing gas flows through chamber 81 of cylinder 56 into
low-pressure chamber 28. Therefore, if the main stream of the
bypassing gas and the gas-suction inlet 44 are distant from each
other in the housing, the temperature of portions of fixed and
revolving scrolls 10 and 14 neighboring the main stream of the
bypassing gas is increased and the portions thermally expand; thus,
the gap between the head of the relevant portion of spiral lap 12
and the inner surface 15a of end plate 15, and also the gap between
the head of the relevant portion of spiral lap 16 and the inner
surface 11a of end plate 11, that is, tip gaps become smaller than
those of other portions, as explained in the first embodiment.
[0063] However, in the present embodiment, the gas-suction inlet 44
is provided near the main stream of the bypassing gas; thus,
increase in the temperature of an area neighboring the main stream
of the bypassing gas can be suppressed by using low-temperature
suction gas which is suctioned from the gas-suction inlet 44.
[0064] Accordingly, when the capacity is controlled, it is possible
to prevent the tip gap near the main stream of the bypassing gas
from decreasing in comparison with the tip gaps of other areas;
thus, scuffing can be prevented between the head of spiral lap 12
and the inner surface 15a of end plate 15, and also between the
head spiral lap 16 and the inner surface 11a of end plate 11.
* * * * *