U.S. patent application number 10/033374 was filed with the patent office on 2002-07-04 for variable displacement compressor.
Invention is credited to Hiramatsu, Osamu, Kawaguchi, Masahiro, Ota, Masaki, Tarutani, Tomoji.
Application Number | 20020085927 10/033374 |
Document ID | / |
Family ID | 18866580 |
Filed Date | 2002-07-04 |
United States Patent
Application |
20020085927 |
Kind Code |
A1 |
Ota, Masaki ; et
al. |
July 4, 2002 |
Variable displacement compressor
Abstract
A cam plate of a variable displacement compressor is easily
manufactured. The compressor includes a lug plate fixed to a drive
shaft, a cam plate supported in an inclinable manner by the drive
shaft, and a hinge mechanism connecting the lug plate and the cam
plate. The cam plate includes a disk engaged with a piston and a
joint formed separately from the disk and fixed to the disk. The
joint forms the hinge mechanism. At least one of the joint and the
disk is press-formed.
Inventors: |
Ota, Masaki; (Kariya-shi,
JP) ; Kawaguchi, Masahiro; (Kariya-shi, JP) ;
Hiramatsu, Osamu; (Kariya-shi, JP) ; Tarutani,
Tomoji; (Kariya-shi, JP) |
Correspondence
Address: |
MORGAN & FINNEGAN, L.L.P.
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
18866580 |
Appl. No.: |
10/033374 |
Filed: |
December 27, 2001 |
Current U.S.
Class: |
417/269 |
Current CPC
Class: |
F04B 27/1072 20130101;
F04B 27/1054 20130101 |
Class at
Publication: |
417/269 |
International
Class: |
F04B 001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 28, 2000 |
JP |
2000-402249 |
Claims
What is claimed is:
1. A variable displacement compressor for drawing, compressing, and
discharging refrigerant with a piston reciprocated by converting
rotation of a drive shaft via a lug plate fixed to the drive shaft,
a cam plate supported in an inclinable manner by the drive shaft,
and a hinge mechanism connecting the lug plate and the cam plate,
wherein the displacement of the compressor varies in accordance
with the inclination of the cam plate, the cam plate comprising: a
disk engaged with the piston; and a joint forming the hinge
mechanism, wherein the joint is formed separately from the disk and
connected to the disk, and at least one of the joint and the disk
is press-formed.
2. The variable displacement compressor according to claim 1,
wherein the cam plate is formed by fixing the joint and the disk to
each other.
3. The variable displacement compressor according to claim 1,
wherein the disk is a press-formed component.
4. The variable displacement compressor according to claim 1,
wherein the joint is a press-formed component.
5. The variable displacement compressor according to claim 1,
wherein the lug plate includes a support arm, the joint of the cam
plate includes a connecting portion, and the hinge mechanism
includes the support arm, the connecting portion of the joint of
the cam plate, and a hinge pin for connecting the support arm and
the connecting portion.
6. The variable displacement compressor according to claim 5,
wherein the joint of the cam plate further includes an engaging
portion for contacting the lug plate and a hinge hole for receiving
the hinge pin.
7. The variable displacement compressor according to claim 6,
wherein the joint further includes a shaft hole through which the
drive shaft is inserted.
8. The variable displacement compressor according to claim 5,
wherein the connecting portion is one of two connecting portions,
and the two connecting portions are separated from each other by a
predetermined distance.
9. A cam plate of a variable displacement compressor, wherein the
compressor draws, compresses, and discharges refrigerant with a
piston reciprocated by converting rotation of a drive shaft via a
lug plate fixed to the drive shaft, the cam plate, and a hinge
mechanism connecting the lug plate and the cam plate, the cam plate
being supported in an inclinable manner by the drive shaft, wherein
the displacement of the compressor varies in accordance with the
inclination of the cam plate, the cam plate comprising: a disk for
engaging the piston; and a press-formed joint formed separately
from the disk and fixed to the disk, wherein the joint includes a
connecting portion connected to the lug plate to form the hinge
mechanism and having a hinge hole engaged with a hinge pin, and an
engaging portion for contacting the lug plate.
10. The cam plate according to claim 9, wherein the joint further
includes a shaft hole through which the drive shaft is
inserted.
11. The cam plate according to claim 9, wherein the disk is a
press-formed component.
12. The cam plate according to claim 9, wherein the connecting
portion is one of two connecting portions, and the two connecting
portions are separated from each other by a predetermined
distance.
13. A variable displacement compressor for drawing, compressing,
and discharging refrigerant with a piston reciprocated by
converting rotation of a drive shaft via a lug plate fixed to the
drive shaft, a cam plate supported in an inclinable manner by the
drive shaft, and a hinge mechanism connecting the lug plate and the
cam plate, wherein the displacement of the compressor varies in
accordance with the inclination of the cam plate, the cam plate
comprising: a disk engaged with the piston; and a press-formed
joint formed separately from the disk and fixed to the disk,
wherein the joint includes two connecting portions each connected
to the lug plate to form the hinge mechanism and separated from
each other by a predetermined distance and having a hinge hole
engaged with a hinge pin, and an engaging portion for contacting
the lug plate.
14. The variable displacement compressor according to claim 13,
wherein the disk is a press-formed component.
15. A method for manufacturing a cam plate of a variable
displacement compressor, wherein the compressor draws, compresses,
and discharges refrigerant with a piston reciprocated by converting
rotation of a drive shaft via a lug plate fixed to the drive shaft,
the cam plate, and a hinge mechanism connecting the lug plate and
the cam plate, the cam plate being supported in an inclinable
manner by the drive shaft, wherein the displacement of the
compressor varies in accordance with the inclination of the cam
plate, the method comprising: press forming a disk having a hole
from a metal plate; bending a metal plate to form a joint having
two bent pieces; and fixing the disk and the joint to each
other.
16. The method according to claim 16, further comprising: forming a
hole for engaging a hinge pin to form the hinge mechanism in each
bent piece.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a cam plate of a variable
displacement compressor.
[0002] Japanese Unexamined Patent Publication No. 10-274153
describes a typical compressor employed in an automobile air
conditioner. As shown in FIGS. 6 and 7, the compressor includes a
lug plate 101, a drive shaft 102, and a cam plate 103. The lug
plate 101 is fixed to the drive shaft 102. A shaft hole 103a
extends through the center of the cam plate 103. The drive shaft
102 extends through the shaft hole 103a. A clearance, having a
predetermined dimension, is formed between the drive shaft 102 and
the wall surface that defines the shaft hole 103a to support the
cam plate 103 in an inclinable manner. A housing 105 accommodates
the lug plate 101, the drive shaft 102, and the cam plate 103. A
piston 104 is retained in each cylinder bore 105a. Each piston 104
is engaged to the peripheral portion of the cam plate 103 by means
of a pair of shoes 106.
[0003] The lug plate 101 and the cam plate 103 are connected to
each other by a hinge mechanism 107. The hinge mechanism 107
includes two guide pins 108, which extend from the cam plate 103,
and support arms 109, which extend from the lug plate 101 in
correspondence with the guide pins 108. Spherical portions 108a are
defined on the distal end of each guide pin 108. A guide bore 109a
extends through each support arm 109. The axis of each guide bore
109a is inclined relative to the axis of the drive shaft 102. The
spherical portion 108a of each guide pin 108 is inserted in the
guide bore 109a of the corresponding guide pin 108.
[0004] The lug plate 101 and the hinge mechanism 107 rotate
integrally with the drive shaft 102. The rotational movement of the
cam plate 103 is converted to reciprocal linear movement of the
pistons 104 by means of the shoes 106. As a result, a compression
cycle, which includes the suction, compression, and discharge of
refrigerant gas, is performed in each cylinder bore 105a. Referring
to FIG. 6, a top dead center portion D1 and a bottom dead center
portion D2 are defined on the inclined cam plate 103. When a
certain point on the inclined cam plate 103 rotates 180 degrees
from the top dead center portion D1, the certain point reaches the
bottom dead center portion D2. The piston 104 engaged with the top
dead center portion D1 of the cam plate 103 is arranged at the top
dead center in the associated cylinder bore 105a. Further, the
piston 104 engaged with the bottom dead center portion D2 of the
cam plate 103 is arranged at the bottom dead center in the
associated cylinder bore 105a.
[0005] The hinge mechanism 107 enables the cam plate 103 to incline
between a maximum inclination position (the state shown in FIG. 6)
and a minimum inclination position (not shown). When the
inclination of the cam plate 103 is altered, the bottom dead center
position changes, although the top dead center position remains the
same. This changes the stroke of the pistons 104 and adjusts the
displacement of the compressor.
[0006] The cam plate 103 has a contacting portion 103b that opposes
the guide pins 108 on the same surface of the cam plate 103 as the
guide pins 108. A seat 101a is defined on the lug plate 101 at a
position corresponding to the contacting portion 103b. When the
inclination of the cam plate 103 is maximal, the contacting portion
103b contacts the seat 101a. In this state, the cam plate 103 is
arranged at the maximum inclination position.
[0007] In the prior art, the cam plate 103 is manufactured by
machining a cast material. As shown in FIG. 7, the cam plate 103,
which is integrally cast, includes a thick portion 103d, the
contacting portion 103b, guide pin holding portions 103e, and a
disk portion 103c. Predetermined portions of the cast cam plate 103
are machined. The guide pins 108, which are formed separately from
the cam plate 103, are fitted to holes that are formed in the guide
pin holding portions 103e. This completes the final cam plate 103.
The parts of the cam plate 103 that undergo machining include the
circumferential surface and the two opposing flat surfaces of the
disk portion 103c, the flat end surfaces of the guide pin holding
portions 103e, the holes for receiving the guide pins 108, the
surface of the contacting portion 103b, and the shaft hole
103a.
[0008] The cam plate 103 is cast and thus includes unnecessary
material. As a result, the cast cam plate 103 is heavy. Further,
many parts of the cam plate 103 must be machined. Thus, it takes
time to machine the cam plate 103.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide a
variable displacement compressor that includes an easily formed cam
plate.
[0010] To achieve the above object, the present invention provides
a variable displacement compressor for drawing, compressing, and
discharging refrigerant with a piston reciprocated by converting
rotation of a drive shaft via a lug plate fixed to the drive shaft,
a cam plate supported in an inclinable manner by the drive shaft,
and a hinge mechanism connecting the lug plate and the cam plate.
The displacement of the compressor varies in accordance with the
inclination of the cam plate. The cam plate includes a disk engaged
with the piston, and a joint forming the hinge mechanism. The joint
is formed separately from the disk and connected to the disk. At
least one of the joint and the disk is press-formed.
[0011] A further perspective of the present invention is a method
for manufacturing a cam plate of a variable displacement
compressor. The compressor draws, compresses, and discharges
refrigerant with a piston reciprocated by converting rotation of a
drive shaft via a lug plate fixed to the drive shaft, the cam
plate, and a hinge mechanism connecting the lug plate and the cam
plate. The cam plate is supported in an inclinable manner by the
drive shaft. The displacement of the compressor varies in
accordance with the inclination of the cam plate. The method
includes press forming a disk having a hole from a metal plate,
bending a metal plate to form a joint having two bent pieces, and
fixing the disk and the joint to each other.
[0012] Other aspects and advantages of the present invention will
become apparent from the following description, taken in
conjunction with the accompanying drawings, illustrating by way of
example the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The invention, together with objects and advantages thereof,
may best be understood by reference to the following description of
the presently preferred embodiments together with the accompanying
drawings in which:
[0014] FIG. 1 is a cross-sectional view showing a variable
displacement compressor according to the present invention;
[0015] FIG. 2 is a perspective view showing a cam plate of the
compressor of FIG. 1;
[0016] FIG. 3 is a perspective view showing a disk of the cam plate
of FIG. 2;
[0017] FIG. 4 is a perspective view showing a joint of the cam
plate of FIG. 2;
[0018] FIG. 5 is a perspective view showing a joint of a further
embodiment according to the present invention;
[0019] FIG. 6 is a cross-sectional view showing a prior art
variable displacement compressor; and
[0020] FIG. 7 is a perspective view showing a cam plate of the
compressor of FIG. 6.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] A single-headed piston type variable displacement compressor
according to the present invention will now be discussed. The
compressor is employed in an air conditioning system of a
vehicle.
[0022] As shown in FIG. 1, a front housing 11 is fixed to the front
end of a cylinder block 12. A rear housing 13 is fixed to the rear
end of the cylinder block 12. A valve plate 14 is arranged between
the rear housing 13 and the cylinder block 12. A crank chamber 15
is defined in the front housing 11 and the cylinder block 12. The
front housing 11 and the cylinder block 12 rotatably support a
drive shaft 16, which extends through the crank chamber 15. The
drive shaft 16 is connected to the vehicle engine (not shown) by a
clutch mechanism such as an electromagnetic clutch. Accordingly,
the drive shaft 16 is rotated if the electromagnetic clutch
connects the drive shaft 16 to the engine when the engine is
running.
[0023] A lug plate 17 is fixed to the drive shaft 16 in the crank
chamber 15. A cam plate 18 is accommodated in the crank chamber 15.
The drive shaft 16 is inserted through a shaft hole 19, which
extends through the central portion of the cam plate 18. The hinge
mechanism 20 connects the lug plate 17 and the cam plate 18.
[0024] The cam plate 18 will now be described with reference to
FIGS. 1 to 4. The cam plate 18 of FIG. 2 is formed by fixing a disk
18a, which is shown in FIG. 3, and a joint 18b, which is shown in
FIG. 4, to each other. The joint 18b forms part of the hinge
mechanism 20. To fix the disk 18a and the joint 18b to each other,
for example, the disk 18a and the joint 18b may be welded (e.g.,
spot welding or projection welding) to each other. Alternatively,
the disk 18a and the joint 18b may be fixed to each other by rivets
or the like. As shown in FIG. 3, a disk hole 19a, which forms part
of the shaft hole 19, extends through the central portion of the
disk 18a. The disk 18a, which has the disk hole 19a, is formed by,
for example, pressing out a sheet of rolled steel. Further,
referring to FIG. 4, the joint 18b is formed by, for example,
pressing a sheet of rolled steel in a C-shaped manner. The joint
18b has two bent pieces, which are separated from each other by a
predetermined distance. A connecting portion 18c and an engaging
portion 32 are defined on each bent piece. A pin hole 18d extends
through the distal end of each connecting portion 18c to receive a
hinge pin 21, which is shown in FIG. 1. A joint hole 19b, which
forms part of the shaft hole 19, extends through the central
portion of the joint 18b.
[0025] Referring to FIG. 1, the lug plate 17 includes a support arm
33, which has a bifurcated portion 33a, corresponding to the
connecting portion 18c. The two connecting portions 18c of the
joint 18b are arranged between the bifurcated portion 33a. Further,
the bifurcated portion 33a has guide holes 33b. The hinge pin 21 is
inserted through the guide holes 33b and the pin holes 18d. The
hinge pin 21 is movable in the guide holes 33b. Thus, the cam plate
18 is movable between a maximum inclination position, in which the
engaging portion 32 contacts the lug plate 17, and a minimum
inclination position, in which the disk 18a of the cam plate 18
contacts a snap ring 31, which is attached to the drive shaft 16. A
compression spring 22 is arranged between the lug plate 17 and the
cam plate 18. The support arm 33 and the hinge pin 21 form part of
the hinge mechanism 20.
[0026] A plurality of equally spaced cylinder bores 12a (only one
shown in FIG. 1) extend through the cylinder block 12 about the
axis L of the drive shaft. A single-headed piston 23 is retained in
each cylinder bore 12a. Each piston 23 is engaged with the
peripheral portion of the disk 18a by means of a pair of shoes
24.
[0027] A suction chamber 25 is defined in the central portion of
the rear housing 13. A discharge chamber 26 is defined in the
peripheral portion of the rear housing 13. A suction port 27, a
suction valve 28, a discharge port 29, and a discharge valve 30 are
provided for each piston 23 in the valve plate 14.
[0028] The lug plate 17 and the hinge mechanism 20 rotate the cam
plate 18 integrally with the drive shaft 16. When the drive shaft
16 rotates, the inclination of the cam plate 18 relative to the
axis L reciprocates the pistons 23 by means of the shoes 24.
[0029] When each piston 23 moves from the top dead center to the
bottom dead center in the associated cylinder bore 12a, refrigerant
gas is drawn into the cylinder bore 12a from the suction chamber 25
through the suction port 27 and the suction valve 28. When the
piston 23 moves from the bottom dead center to the top dead center,
the refrigerant gas drawn into the cylinder bore 12a is compressed
and then discharged into the discharge chamber 26 through the
discharge port 29 and the discharge valve 30.
[0030] A bleeding passage 35 connects the crank chamber 15 and the
suction chamber 25. A gas supply passage 36 connects the discharge
chamber 26 and the crank chamber 15. A displacement control valve
37 is arranged in the gas supply passage 36. A pressure sensing
passage 38 connects the suction chamber 25 and the displacement
control valve 37. The displacement control valve 37 detects the
pressure in the suction chamber 25 through the pressure sensing
passage 38 and is controlled based on the detected pressure.
[0031] The displacement control valve 37 adjusts the opening degree
of the gas supply passage 36 to change the pressure in the crank
chamber 15 and adjust the differential pressure acting on the
pistons 23 (i.e., the difference between the pressure in the crank
chamber 15 and the pressure in the cylinder bores 12a). This alters
the inclination of the cam plate 18, changes the stroke of the
pistons 23, and varies the displacement of the compressor.
[0032] When the cooling load is small, the pressure in the suction
chamber 25, or the suction pressure, is lower than a predetermined
value. In this state, the displacement control valve 37 functions
to increase the opening degree of the gas supply passage 36. Thus,
the refrigerant gas drawn into the crank chamber 15 from the
discharge chamber 26 increases the pressure in the crank chamber
15. Accordingly, the hinge pin 21 moves in the guide holes 33b
toward the axis L. Further, the cam plate 18 moves along the drive
shaft 16 toward the minimum inclination position, as its
inclination decreases. This decreases the stroke of the pistons 23.
As a result, the displacement of the compressor decreases, and the
suction pressure is increased so that it approaches the
predetermined value.
[0033] When the cooling load is large, the suction pressure is
greater than a predetermined value. Thus, the displacement control
valve 37 functions to decrease the opening degree of the gas supply
passage 36, and the refrigerant gas in the crank chamber 15 is
released into the suction chamber 25 through the bleeding passage
35. This decreases the pressure in the crank chamber 15.
Accordingly, the hinge pin 21 moves in the guide holes 33b away
from the axis L. Simultaneously, the cam plate 18 moves along the
drive shaft 16 toward the maximum inclination position, as its
inclination increases. This increases the stroke of the pistons 23.
As a result, the displacement of the compressor increases, and the
suction pressure is decreased so that it approaches the
predetermined value.
[0034] The advantages of the preferred and illustrated embodiment
will now be described.
[0035] (1) The cam plate 18 is formed by fixing the disk 18a and
the joint 18b, which are press-formed, to each other. This
drastically decreases portions that undergo machining in comparison
to the prior art in which a cast material is machined. Accordingly,
the manufacturing process is simplified and the time required for
machining is shortened.
[0036] (2) Since the cam plate 18 is press-formed, the cam plate 18
does not include unnecessary material. Thus, in comparison to an
integrally cast cam plate, the cam plate 18 is light.
[0037] (3) The disk 18a and the joint 18b are each press-formed.
Thus, the disk 18a and the joint 18b may be formed from
high-strength material or general-purpose material. Accordingly,
each component may be formed from the optimal material. This
improves the quality and reliability of the compressor.
[0038] It should be apparent to those skilled in the art that the
present invention may be embodied in many other specific forms
without departing from the spirit or scope of the invention.
Particularly, it should be understood that the present invention
may be embodied in the following forms.
[0039] Referring to FIG. 5, a generally U-shaped plate 50 may be
employed as the joint. The joint 50 is press-formed so that its
distal portions, which serve as connecting portions 52, is inclined
relative to its basal portion, which serves as an engaging portion
51. Each connecting portion 52 includes a pin hole 53 through which
the hinge pin 21 is inserted. Fastening holes 54 are formed in the
joint 50. Rivets are inserted in the fastening holes 54 and
fastened to the joint 50 to fix the joint 50 and the disk 18a to
each other. This structure has the same advantages as the above
embodiment.
[0040] The present examples and embodiments are to be considered as
illustrative and not restrictive, and the invention is not to be
limited to the details given herein, but may be modified within the
scope and equivalence of the appended claims.
* * * * *