U.S. patent application number 10/450926 was filed with the patent office on 2004-03-18 for compressor.
Invention is credited to Adaniya, Taku, Kanai, Akinobu, Kawaguchi, Masahiro, Mnami, Kazuhiko, Ota, Masaki, Tanaka, Hirohiko.
Application Number | 20040052647 10/450926 |
Document ID | / |
Family ID | 19118451 |
Filed Date | 2004-03-18 |
United States Patent
Application |
20040052647 |
Kind Code |
A1 |
Kanai, Akinobu ; et
al. |
March 18, 2004 |
Compressor
Abstract
A compressor includes a compressor main body and a power
transmission mechanism. The power transmission mechanism includes a
pulley and a hub. The pulley has a first inner cylinder and a
second inner cylinder, which are apart from each other in the axial
direction of the pulley. A one-way clutch is located on a power
transmission path between the first inner cylinder and the hub. A
bearing is located between the first inner cylinder and the hub. A
bearing is located between the second inner cylinder and a housing
of the compressor main body. A power transmission pin for
discontinuing an excessive power transmission is located on a power
transmission path between an engine of a vehicle and a drive
shaft.
Inventors: |
Kanai, Akinobu; (Aichi,
JP) ; Kawaguchi, Masahiro; (Aichi, JP) ; Ota,
Masaki; (Aichi, JP) ; Adaniya, Taku; (Aichi,
JP) ; Mnami, Kazuhiko; (Aichi, JP) ; Tanaka,
Hirohiko; (Aichi, JP) |
Correspondence
Address: |
Kurt E Richter
Morgan & Finnegan
345 Park Avenue
New York
NY
10154
US
|
Family ID: |
19118451 |
Appl. No.: |
10/450926 |
Filed: |
June 13, 2003 |
PCT Filed: |
September 27, 2002 |
PCT NO: |
PCT/JP02/10040 |
Current U.S.
Class: |
417/222.1 ;
417/222.2; 417/223 |
Current CPC
Class: |
F04B 27/0895 20130101;
F16H 2055/366 20130101 |
Class at
Publication: |
417/222.1 ;
417/223; 417/222.2 |
International
Class: |
F04B 001/26 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 27, 2001 |
JP |
2001-297360 |
Claims
1. A compressor, comprising: a compressor main body, wherein the
compressor main body includes a housing and a drive shaft, which is
supported by the housing, and wherein the compressor main body
compresses refrigerant in accordance with rotation of the drive
shaft; an electric part, wherein the electric part at least
functions as a motor; a first rotating body, wherein the first
rotating body is rotated by an external drive source; a second
rotating body secured to the drive shaft to rotate integrally with
the drive shaft, wherein the second rotating body is operably
coupled to the first rotating body, and wherein power is directly
transmitted from the electric part to the second rotating body; a
first cylinder and a second cylinder located on the first rotating
body, wherein the first cylinder and the second cylinder are apart
from each other; a one-way clutch located on a power transmission
path between the first cylinder and the second cylinder; a first
ball bearing located between the first cylinder and the second
rotating body; a second ball bearing located between the second
cylinder and the housing; and a discontinuing mechanism located on
a power transmission path between the external drive source and the
drive shaft, wherein the discontinuing mechanism discontinues
excessive torque transmission from the external drive source to the
drive shaft.
2. The compressor according to claim 1, further comprising an
elastic member for absorbing misalignment between the axis of the
first ball bearing and the axis of the second ball bearing.
3. The compressor according to claim 1 or 2, wherein the
discontinuing mechanism includes a breakable member, and wherein
the breakable member breaks when torque transmitted from the
external drive source to the drive shaft is excessive.
4. The compressor according to claim 3, wherein the breakable
member is made of sintered metal or low-carbon steel.
5. The compressor according to claim 3 or 4, wherein at least part
of the first rotating body or at least part of the second rotating
body functions as the breakable member.
6. The compressor according to claim 5, wherein at least one of the
first rotating body and the second rotating body has an upstream
rotating body and a downstream rotating body, wherein the upstream
rotating body is located upstream of the downstream rotating body
in the power transmission path between the external drive source
and the drive shaft, and wherein the breakable member is located in
a power transmission path between the upstream rotating body and
the downstream rotating body.
7. The compressor according to any one of claims 1 to 6, wherein
the first ball bearing has a plurality of rolling elements arranged
in a line in the circumferential direction of the first ball
bearing.
8. The compressor according to any one of claims 1 to 7, wherein
the electric part is located inside the first rotating body.
9. The compressor according to claim 8, wherein the first cylinder
and the second cylinder are separate from each other in the axial
direction of the first rotating body.
10. The compressor according to any one of claims 1 to 9, wherein
the compressor main body is designed such that the discharge
displacement per one rotation of the drive shaft can be varied.
11. The compressor according to claim 10, wherein the compressor
main body is connected to an external refrigerant circuit, and
wherein the compressor main body and the external refrigerant
circuit form a refrigerant circuit, the compressor main body
includes: a control pressure zone, wherein the discharge
displacement per one rotation of the drive shaft is varied in
accordance with the pressure in the control pressure zone; a
pressure control passage, wherein the pressure control passage
connects the control.pressure zone to a pressure zone, which is
exposed to pressure that is different from the pressure in the
control pressure zone; and a control valve located in the pressure
control passage, wherein the control valve adjusts the opening
degree of the pressure control passage to control the pressure in
the control pressure zone.
12. The compressor according to claim 11, wherein the control valve
includes: a valve body; a pressure sensing member, wherein the
pressure sensing member is displaced in accordance with the
pressure difference between two pressure monitoring points located
in the refrigerant circuit, wherein the pressure sensing member
moves the valve body in accordance with the pressure difference,
and wherein the discharge displacement per one rotation of the
drive shaft is varied to cancel the fluctuation of the pressure
difference; and an actuator, wherein the actuator urges the
pressure sensing member in accordance with an external command, and
wherein the force of the actuator exerted against the pressure
sensing member reflects a target value of the pressure
difference.
13. The compressor according to any one of claims 10 to 12, wherein
the compressor main body is designed such that the discharge
displacement per one rotation of the drive shaft can be varied to
substantially zero.
Description
TECHNICAL FIELD
[0001] The present invention relates to a compressor that is driven
selectively by an external drive source and an electric part.
BACKGROUND ART
[0002] Japanese Laid-Open Patent Publication No. 2001-140757
discloses a hybrid compressor for a vehicle that is driven by an
electric part, which is a motor, while the external drive source,
which is an engine of the vehicle, is stopped.
[0003] The hybrid compressor includes a drive shaft and a
compression mechanism, which is driven by the drive shaft. A rotary
body is secured to the drive shaft to rotate integrally with the
drive shaft. The rotary body supports a pulley via a bearing such
that the pulley rotates relative to the rotary body. The rotary
body has a rotor, which forms part of the motor so that the drive
shaft is rotated by the motor. A one-way clutch is located on a
power transmission path between the pulley and the rotary body. The
one-way clutch permits power transmission from the pulley to the
rotary body such that rotational force in only one direction is
transmitted. Accordingly, although the engine for traveling is
stopped, the compression mechanism is driven by the motor. When the
motor drives the compression mechanism, the power of the motor is
prevented from being transmitted to the engine.
[0004] The one-way clutch eliminates the need to use an
electromagnetic clutch for selectively permitting and discontinuing
power transmission between the pulley and the rotary body, which
simplifies the structure of the compressor. However, in the case
the one-way clutch is used, if an abnormality, such as a dead lock,
occurs in the compression mechanism while the compression mechanism
is driven by the engine, an excessive load is applied to the
engine.
DISCLOSURE OF THE INVENTION
[0005] Accordingly, it is an objective of the present invention to
provide a compressor that reduces weight, size, and cost, and
prevents an excessive load from being applied to an external drive
source when the compressor has an abnormality.
[0006] To achieve the above objective, the present invention
provides a compressor, which includes a compressor main body, an
electric part, a first rotating body, a second rotating body, a
first cylinder, a second cylinder, a one-way clutch, a first ball
bearing, a second ball bearing, and a discontinuing mechanism. The
compressor main body includes a housing and a drive shaft, which is
supported by the housing. The compressor main body compresses
refrigerant in accordance with rotation of the drive shaft. The
electric part at least functions as a motor. The first rotating
body is rotated by an external drive source. The second rotating
body is secured to the drive shaft to rotate integrally with the
drive shaft. The second rotating body is operably coupled to the
first rotating body and power is directly transmitted from the
electric part to the second rotating body. The first cylinder and
the second cylinder are located on the first rotating body. The
first cylinder and the second cylinder are apart from each other.
The one-way clutch is located on a power transmission path between
the first cylinder and the second cylinder. The first ball bearing
is located between the first cylinder and the second rotating body.
The second ball bearing is located between the second cylinder and
the housing. The discontinuing mechanism is located on a power
transmission path between the external drive source and the drive
shaft and discontinues excessive torque transmission from the
external drive source to the drive shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a cross-sectional view illustrating a compressor
according to a first embodiment of the present invention;
[0008] FIG. 2 is a cross-sectional view illustrating the control
valve of the compressor shown in FIG. 1;
[0009] FIG. 3 is a cross-sectional view for explaining the movement
of the operating rod of the control valve shown in FIG. 2;
[0010] FIG. 4 is an enlarged cross-sectional view illustrating the
power transmission mechanism of the compressor shown in FIG. 1;
[0011] FIG. 5(a) is a front view illustrating a downstream pulley
member according to a second embodiment of the present
invention;
[0012] FIG. 5(b) is a cross-sectional view illustrating a power
transmission mechanism according to a second embodiment;
[0013] FIGS. 6(a) and 6(b) are partial cross-sectional views
illustrating the one-way clutch according to the first embodiment;
and
[0014] FIG. 7 is a partial cross-sectional view illustrating a
power transmission mechanism according to a modified
embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0015] A first embodiment of the present invention will now be
described with reference to FIGS. 1 to 4, 6(a), and 6(b). The left
side of FIG. 1 is defined as the front end of the compressor, and
the right side of FIG. 1 is defined as the rear end of the
compressor.
[0016] As shown in FIG. 1, a compressor main body C, which forms
part of a vehicular air conditioner, includes a cylinder block 11,
a front housing member 12, and a rear housing member 14. The front
housing member 12 is secured to the front end of the cylinder block
11. The rear housing member 14 is attached to the rear end of the
cylinder block 11 with a valve plate assembly 13 located in
between. The cylinder block 11, the front housing member 12, the
valve plate assembly 13, and the rear housing member 14 form a
housing assembly of the compressor main body C.
[0017] The cylinder block 11 and the front housing member 12 define
a control pressure zone, which is a crank chamber 15. The housing
assembly of the compressor main body C rotatably supports a drive
shaft 16, which extends through the crank chamber 15. The front end
of the drive shaft 16 is supported by a radial bearing 12A, which
is secured to the front wall of the front housing member 12. The
rear end of the drive shaft 16 is supported by a radial bearing
11A, which is secured to the cylinder block 11.
[0018] The front end of the drive shaft 16 projects outside through
the front wall of the front housing member 12. The front end of the
drive shaft 16 is operably coupled to an external drive source,
which is an engine E of a vehicle in the first embodiment, via a
power transmission mechanism PT and a belt 18. The belt 18 is wound
about a first rotating body, which is a pulley 17 in the first
embodiment. The pulley 17 forms part of the power transmission
mechanism PT. The power transmission mechanism PT and the
compressor main body C form the compressor.
[0019] An electric part, which is a motor generator MG in the first
embodiment, is located between the pulley 17 and the drive shaft 16
in a power transmission path between the engine E of the vehicle
and the drive shaft 16. The motor generator MG is formed by an
induction machine and functions as a motor and a generator. In the
first embodiment, when the engine E of the vehicle is running,
power from the engine E is always transmitted to the drive shaft 16
and the motor generator MG. At this time, the motor generator MG
functions as a generator. If air conditioning is necessary when the
engine E of the vehicle is stopped, the motor generator MG
functions as a motor to rotate the drive shaft 16.
[0020] A lug plate 19 is located in the crank chamber 15 and is
secured to the drive shaft 16 to rotate integrally with the drive
shaft 16. A drive plate, which is a swash plate 20 in the first
embodiment, is located in the crank chamber 15. The swash plate 20
is supported on the drive shaft 16, and slides along and inclines
with respect to the drive shaft 16. The swash plate 20 is coupled
to the lug plate 19 via a hinge mechanism 21. The hinge mechanism
21 causes the swash plate 20 to rotate integrally with the lug
plate 19 and the drive shaft 16, and permits the swash plate 20 to
slide in the axial direction of the drive shaft 16 and incline with
respect to the drive shaft 16.
[0021] The minimum inclination angle of the swash plate 20 is
determined by a ring 22, which is secured to the drive shaft 16,
and a spring 23, which is located between the ring 22 and the swash
plate 20. The swash plate 20 is movable between a minimum
inclination angle position indicated by a solid line in FIG. 1, and
a maximum inclination angle position indicated by a chain
double-dashed line in FIG. 1. When the swash plate 20 is located at
the minimum inclination angle position, the angle between the swash
plate 20 and a surface that is perpendicular to the axis of the
drive shaft 16 is closest to zero.
[0022] Cylinder bores 24 (only one shown) are formed in the
cylinder block 11. The cylinder bores 24 extend along the drive
shaft 16 and are arranged about the axis of the drive shaft 16 at
equal angular intervals. A single headed piston 25 is accommodated
in each cylinder bore 24 to reciprocate in the cylinder bore 24.
Both ends of each cylinder bore 24 are closed by the valve plate
assembly 13 and the corresponding piston 25. Each cylinder bore 24
defines a compression chamber the volume of which varies in
accordance with the reciprocation of the corresponding piston 25.
Each piston 25 is coupled to the peripheral portion of the swash
plate 20 by a pair of shoes 26. Therefore, when the swash plate 20
rotates with the drive shaft 16, the shoes 26 convert the rotation
of the swash plate 20 into reciprocation of the pistons 25.
[0023] The cylinder block 11, the drive shaft 16, the lug plate 19,
the swash plate 20, the hinge mechanism 21, the pistons 25, and the
shoes 26 form a compression mechanism of a variable displacement
piston type compressor.
[0024] The rear housing member 14 defines a suction pressure zone,
which is a suction chamber 27, and a discharge pressure zone, which
is a discharge chamber 28. The openings of the suction chamber 27
and the discharge chamber 28 that face the valve plate assembly 13
are closed by the valve plate assembly 13. The valve plate assembly
13 has suction ports 29, suction valve flaps 30, discharge ports
31, and discharge valve flaps 32. Each set of the suction port 29,
the suction valve flap 30, the discharge port 31, and the discharge
valve flap 32 corresponds to one of the cylinder bores 24. When
each piston 25 moves from the top dead center position to the
bottom dead center position, refrigerant gas in the suction chamber
27 is drawn into the corresponding cylinder bore 24 via the
corresponding suction port 29 and suction valve flap 30. When each
piston 25 moves from the bottom dead center position to the top
dead center position, refrigerant gas in the corresponding cylinder
bore 24 is compressed to a predetermined pressure and is discharged
to the discharge chamber 28 via the corresponding discharge port 31
and discharge valve flap 32.
[0025] A crank chamber pressure control mechanism controls the
internal pressure of the crank chamber 15, or a crank pressure Pc,
to control the inclination angle of the swash plate 20. The crank
chamber pressure control mechanism is formed by a bleed passage 33,
a supply passage (34, 96, 98), and a control valve 35. The bleed
passage 33 is formed in the housing assembly of the compressor main
body C to connect the suction chamber 27 to the crank chamber 15.
The supply passage (34, 96, 98) connects the crank chamber 15 to
the discharge chamber 28. The control valve 35 is located in the
supply passage (34, 96, 98). The supply passage (34, 96, 98)
includes a pipe 96, a second pressure introduction passage 98, and
a communication passage 34. The pipe 96 is connected to an outlet
of the discharge chamber 28. The second pressure introduction
passage 98 extends from a second pressure monitoring point P2
located in the pipe 96 to the control valve 35. The communication
passage 34 extends from the control valve 35 to the crank chamber
15.
[0026] Refrigerant in the crank chamber 15 is released into the
suction chamber 27 through the bleed passage 33. On the other
hands, the control valve 35 adjusts the flow rate of refrigerant
supplied to the crank chamber 15 from the discharge chamber 28
through the supply passage (34, 96, 98). In accordance with a
change in the crank pressure Pc, the difference between the crank
pressure Pc and the pressure in each cylinder bore 24 is changed,
which alters the inclination angle of the swash plate 20. As a
result, the stroke of each piston 25, that is, the discharge
displacement (displacement of the compressor main body C) per one
rotation of the drive shaft 16, is controlled. In the compressor
main body C of the first embodiment, the discharge displacement per
one rotation of the drive shaft 16 approaches zero when the swash
plate 20 is located at the minimum inclination angle position.
[0027] The suction chamber 27 and the discharge chamber 28 are
connected to each other by an external refrigerant circuit 90. The
compressor main body C and the external refrigerant circuit 90 form
the refrigerant circuit of the vehicular air-conditioner. The
external refrigerant circuit 90 includes a condenser 91, a
decompression device, which is a temperature type expansion valve
92 in this embodiment, and an evaporator 93. The opening degree of
the expansion valve 92 is feedback controlled based on the
temperature of the refrigerant detected by a heat sensitive tube
94, which is located at the outlet or downstream of the evaporator
93, or the pressure at the outlet of the evaporator 93. The
expansion valve 92 supplies appropriate amount of liquid
refrigerant to the evaporator 93 in accordance with the heat load
applied to the refrigerant circuit to adjust the flow rate of
refrigerant in the external refrigerant circuit 90.
[0028] The external refrigerant circuit 90 includes a pipe 95, or a
low pressure passage, which connects the outlet of the evaporator
93 to the suction chamber 27 of the compressor main body C. The low
pressure passage and the suction chamber 27 form a low pressure
zone. The external refrigerant circuit 90 also includes the pipe
96, or a high pressure passage, which connects the discharge
chamber 28 of the compressor main body C to the inlet of the
condenser 91. The high pressure passage and the discharge chamber
28 form a high pressure zone. The compressor main body C draws in
and compresses refrigerant gas that is introduced into the suction
chamber 27 from the low pressure passage and discharges the
compressed gas to the discharge chamber 28, which is connected to
the high pressure passage.
[0029] As the flow rate of refrigerant (refrigerant flow rate Q)
that flows through the refrigerant circuit increases, the pressure
loss per unit length of the circuit or the pipe increases. That is,
the pressure loss between the pressure monitoring points P1 and P2
located in the refrigerant circuit has a positive correlation with
the refrigerant flow rate Q in the refrigerant circuit. A primary
pressure .DELTA.PX, which is the pressure loss between two pressure
monitoring points P1 and P2, that is, the difference between the
pressure PdH at the first pressure monitoring point P1 and the
pressure PdL at the second pressure monitoring point P2, reflects
the refrigerant flow rate Q in the refrigerant circuit.
[0030] In the first embodiment, the first pressure monitoring point
P1 for monitoring high pressure in the upstream side is located in
the discharge chamber 28, which corresponds to the most upstream
section of the pipe 96. The second pressure monitoring point P2 for
monitoring low pressure in the downstream side is located in the
pipe 96 apart from the first pressure monitoring point P1 by a
predetermined distance. The pressure PdH at the first pressure
monitoring point P1 is introduced to the control valve 35 through a
first pressure introduction passage 97 (shown in FIG. 2 only) and
the pressure PdL at the second pressure monitoring point P2 is
introduced to the control valve 35 through the second pressure
introduction passage 98.
[0031] Pressure difference increasing means for clarifying or
increasing the primary pressure .DELTA.PX, or a fixed restrictor
99, is located in the pipe 96 between the pressure monitoring
points P1 and P2. Since the fixed restrictor 99 is located between
the pressure monitoring points P1 and P2, the pressure monitoring
points P1 and P2 need not be separated from each other by a large
amount. Therefore, the second pressure monitoring point P2 can be
located close to the compressor main body C, which shortens the
second pressure introduction passage 98 between the second pressure
monitoring point P2 and the control valve 35. Although the pressure
PdL at the second pressure monitoring point P2 is decreased
compared to the pressure PdH at the first pressure monitoring point
P1 by the operation of the fixed restrictor 99, the pressure PdL is
sufficiently higher than the crank pressure Pc.
[0032] As shown in FIG. 2, the control valve 35 includes an inlet
valve portion 101, which forms the upper half of the control valve
35, and a solenoid portion 102, which forms the lower half of the
control valve 35. The inlet valve portion 101 adjusts the opening
degree, or the restricting degree, of the supply passage, which
connects the second pressure monitoring point P2 to the crank
chamber 15. The solenoid portion 102 is an electromagnetic actuator
for urging the operating rod 103 located inside the control valve
35 based on the external current supply control. The operating rod
103 includes a coupling portion 105, which is the distal end, a
valve body 106, which is located at the substantial center, and a
guide rod portion 107, which is the proximal end. The valve body
106 forms part of the guide rod portion 107. Assuming that the
diameter of the coupling portion 105 is represented by d1, the
diameter of the guide rod portion 107 is represented by d2, d1 is
smaller than d2. Assuming that the circle ratio is n, the
cross-sectional area SB of the coupling portion 105 is represented
by .pi.(d1/2).sup.2, and the cross-sectional area SD of the guide
rod portion 107 is represented by .pi.(d2/2).sup.2.
[0033] A valve housing 108 of the control valve 35 includes a cap
109, an upper half main body 110, which forms the main outline of
the inlet valve portion 101, and a lower half main body 111, which
forms the main outline of the solenoid portion 102. A valve chamber
112 and a communication passage 113 are defined in the upper half
main body 110 of the valve housing 108. A pressure sensing chamber
114 is defined between the upper half main body 110 and the cap
109, which is inserted in the upper portion of the upper half main
body 110. The operating rod 103 is located inside the valve chamber
112, the communication passage 113, and a pressure sensing chamber
114 and is movable in the axial direction (vertical direction in
FIG. 2). The valve chamber 112 and the communication passage 113
are selectively communicated in accordance with the position of the
operating rod 103. The communication passage 113 and part of the
pressure sensing chamber 114 (second pressure chamber 115, which
will be described later) are always communicated.
[0034] The bottom wall of the valve chamber 112 is formed by the
upper end of a fixed iron core 116, which will be described later.
A port 117 is formed in the circumferential wall of the valve
housing 108, which surrounds the valve chamber 112. The port 117
connects the valve chamber 112 to the crank chamber 15 via the
communication passage 34, which is the downstream section of the
supply passage. A port 118 is formed in the circumferential wall of
the valve housing 108, which surrounds the pressure sensing chamber
114 (the second pressure chamber 115). The port 118 connects the
communication passage 113 to the second pressure monitoring point
P2 via the pressure sensing chamber 114 (the second pressure
chamber 115) and the second pressure introduction passage 98, which
is the upstream section of the supply passage. The port 117, the
valve chamber 112, the communication passage 113, the pressure
sensing chamber 114 (the second pressure chamber 115), and the port
118 form a passage inside the control valve, and the passage inside
the control valve forms part of the supply passage.
[0035] The valve body 106 of the operating rod 103 is located
inside the valve chamber 112. The inner diameter d3 of the
communication passage 113 is greater than the diameter d1 of the
coupling portion 105 of the operating rod 103 and is smaller than
the diameter d2 of the guide rod portion 107. That is, the
cross-sectional area (opening area) SC of the communication passage
113 is .pi.(d3/2).sup.2, and the opening area SC is greater than
the cross-sectional area SB of the coupling portion 105 and is
smaller than the cross-sectional area SD of the guide rod portion
107. Therefore, a step located between the valve chamber 112 and
the communication passage 113 function as a valve seat 119 and the
communication passage 113 function as a valve hole. When the
operating rod 103 moves from the lowermost position shown in FIG. 2
to the uppermost position at which the valve body 106 contacts the
valve seat 119, the communication passage 113 is disconnected. The
valve body 106 of the operating rod 103 moves in the axial
direction to adjust the opening degree of the supply passage.
[0036] A first pressure sensing member, which is a movable wall 120
in the first embodiment, is located in the pressure sensing chamber
114 and is movable in the axial direction. The movable wall 120 is
cup-shaped. The bottom wall of the movable wall 120 divides the
pressure sensing chamber 114 into a high pressure chamber, which is
a first pressure chamber 121 in the first embodiment, and a low
pressure chamber, which is a second pressure chamber 115 in the
first embodiment. The movable wall 120 serves as a partition
between the first pressure chamber 121 and the second pressure
chamber 115. The movable wall 120 does not permit fluid to directly
move between the first pressure chamber 121 and the second pressure
chamber 115. The cross-sectional area SA of the movable wall 120 is
greater than the opening area SC of the communication passage
113.
[0037] The first pressure chamber 121 is always communicated with
the first pressure monitoring point P1, which is the discharge
chamber 28, via a port 122, which is formed in the cap 109 and the
first pressure introduction passage 97. On the other hand, the
second pressure chamber 115 is always communicated with the second
pressure monitoring point P2 via the port 118, which is part of the
supply passage, and the second pressure introduction passage 98.
That is, the pressure PdH at the first pressure monitoring point P1
is introduced into the first pressure chamber 121, and the pressure
PdL at the second pressure monitoring point P2 is introduced into
the second pressure chamber 115. Therefore, the upper and lower
surfaces of the movable wall 120 serve as pressure receiving
surfaces that are exposed to the pressures PdH and PdL,
respectively. The movable wall 120 is displaced in accordance with
the difference (the primary .DELTA.PX) between the pressure PdH and
the pressure PdL.
[0038] The distal end of the coupling portion 105 of the operating
rod 103 enters the second pressure chamber 115. The distal end of
the coupling portion 105 is attached to the movable wall 120. The
first pressure chamber 121 accommodates a return spring 123. The
return spring 123 urges the movable wall 120 from the first
pressure chamber 121 toward the second pressure chamber 115.
[0039] The solenoid portion 102 includes a cup-shaped cylinder 124.
A fixed iron core 116 is fitted in the upper portion of the
cylinder 124 so that a solenoid chamber 125 is defined in the
cylinder 124. A plunger, which is a movable iron core 126 in the
first embodiment, is accommodated in the solenoid chamber 125 and
is movable in the axial direction. A guide hole 127 is formed at
the center of the fixed iron core 116 and extends in the axial
direction. A guide rod portion 107 of the operating rod 103 is
located in the guide hole 127 and is movable in the axial
direction. A little space (not shown) is formed between the inner
circumferential surface of the guide hole 127 and the guide rod
portion 107. The valve chamber 112 and the solenoid chamber 125 are
connected to each other via the space. That is, the solenoid
chamber 125 is exposed to the crank pressure Pc that is the same as
the crank pressure Pc in the valve chamber 112.
[0040] The proximal end of the operating rod 103 is accommodated in
the solenoid chamber 125. That is, the lower end of the guide rod
portion 107 is located inside the solenoid chamber 125 and is
fitted and calked to a hole made through the center of the movable
iron core 126. Therefore, the movable iron core 126 and the
operating rod 103 integrally move in the vertical direction. The
solenoid chamber 125 accommodates a shock absorbing spring 128,
which urges the movable iron core 126 toward the fixed iron core
116. In other words, the shock absorbing spring 128 urges the
movable iron core 126 and the operating rod 103 upward. The force
of the shock absorbing spring 128 is smaller than the force of the
return spring 123. The return spring 123 functions as restore means
for returning the movable iron core 126 and the operating rod 103
to the lowermost position when the solenoid portion 102 is
de-excited.
[0041] A coil 129 is wound about the fixed iron core 116 and the
movable iron core 126. A drive signal is sent to the coil 129 from
a drive circuit 131 based on a command from a controller 130. The
coil 129 generates an electromagnetic force the magnitude of which
corresponds to the value of current supplied to the coil 129. The
electromagnetic force attracts the movable iron core 126 toward the
fixed iron core 116, which urges the operating rod 103 upward. The
current supplied to the coil 129 is controlled by adjusting the
applied voltage to the coil 129. The applied voltage is generally
controlled by means for changing the voltage or means that utilizes
pulse-width modulation. The pulse-width modulation is a method for
adjusting the average voltage by applying a pulse voltage having a
constant cycle and changing the on time of the pulse. The applied
voltage is represented by the pulse voltage multiplied by the on
time of the pulse divided by the pulse cycle. The on time of the
pulse divided by the pulse cycle is referred to as a duty ratio.
The voltage control that makes use of the pulse width modulation is
sometimes referred to as a duty control. When the pulse width
modulation is employed, the current intermittently varies, which
reduces the hysteresis of the electromagnet. It is also common to
measure the value of current that flows through the coil 129, and
feedback control the applied voltage based on the measured current
value. In the first embodiment, the duty control is employed. Due
to the structure of the control valve 35, a smaller duty ratio
increases the opening degree of the control valve 35. A greater
duty ratio decreases the opening degree of the control valve
35.
[0042] The opening degree of the control valve shown in FIG. 2 is
determined by the axial position of the operating rod 103, which
includes the valve body 106. The operating conditions and the
characteristics of the control valve 35 will become apparent by
considering, in a comprehensive manner, the forces that act on each
part of the operating rod 103.
[0043] As shown in FIG. 3, a downward force f1 of the return spring
123 and a downward force based on the primary pressure .DELTA.PX,
which is the difference between the pressure PdH and the pressure
PdL applied to the movable wall 120, act on the coupling portion
105 of the operating rod 103. The pressure receiving area of the
upper surface of the movable wall 120 is represented by SA but the
pressure receiving area of the lower surface of the movable wall
120 is represented by (SA-SB). Assume that downward direction is
defined as the positive direction. The sum .SIGMA.F1 of the forces
that act on the coupling portion 105 is expressed by the following
equation I.
.SIGMA.F1=PdH.times.SA-PdL(SA-SB)+f1 (Equation I)
[0044] On the other hand, an upward force f2 of the shock-absorbing
spring 128 and an upward electromagnetic force F, which is
generated by the solenoid portion 102, act on the guide rod portion
107 of the operating rod 103. The pressures applied to all the
exposed surfaces of the valve body 106, the guide rod portion 107,
and the movable iron core 126 are simplified as follows. First, the
upper end surface 132 of the valve body 106 is divided into the
inner circumferential section and the outer circumferential section
by an imaginary cylinder (shown by two broken lines in FIG. 3),
which extends from the inner circumferential surface of the
communication passage 113. The pressure PdL acts in a downward
direction on the inner circumferential section (area: SC-SB). The
crank pressure Pc acts in a downward direction on the outer
circumferential section (area: SD-SC). Taking the pressure balance
between the upper and lower surfaces of the movable iron core 126
into account, the crank pressure Pc in the solenoid chamber 125
urges the lower end surface 133 of the guide rod portion 107 upward
by the area corresponding to the cross-sectional area SD of the
guide rod portion 107. Assume that the upward direction is defined
as the positive direction. The sum .SIGMA.F2 of the forces that act
on the valve body 106 and the guide rod portion 107 is expressed by
the following equation II. 1 F2 = F + f2 - PdL ( SC - SB ) - Pc (
SD - SC ) + Pc .times. SD = F + f2 + Pc .times. SD - PdL ( SC - SB
) ( Equation II )
[0045] In the process of calculating the equation II, --Pc.times.SD
was canceled by +Pc.times.SD, and the term Pc.times.SC remained.
This means that the effective pressure receiving area of the guide
rod portion 107, which includes the valve body 106, related to the
crank pressure Pc can be expressed as SD-(SD-SC)=SC when
considering on the assumption that the crank pressure Pc
intensively acts on only the lower end surface 133 of the guide rod
portion 107 when the crank pressure Pc acts on the upper and lower
end surfaces 132, 133 of the guide rod portion 107. As far as the
crank pressure Pc is concerned, the effective pressure receiving
area of the guide rod portion 107 is equal to the opening area SC
of the communication passage 113 regardless of the cross-sectional
area SD of the guide rod portion 107. In this specification, when
pressures of the same kind act on both ends of a member such as a
rod, the pressure receiving area having an effect that can be
assumed that the pressure acts intensively on one end only is
called the "effective pressure receiving area"
[0046] Since the operating rod 103 is an integrated member formed
by connecting the coupling portion 105 to the guide rod portion
107, its axial position is determined by the dynamic balance of
.SIGMA.F1=.SIGMA.F2. After the equation .SIGMA.F1=.SIGMA.F2 is
sorted, the following equation III is obtained.
F-f1+f2=(PdH-PdL)SA+(PdL-Pc)SC (Equation III)
[0047] In the Equation III, f1, f2, SA, SC are parameters that are
defined in the steps of mechanical design. The electromagnetic
force F is a variable parameter that changes in accordance with the
power supplied to the coil 129. The pressure PdH, PdL and the crank
pressure Pc are variable parameters that change in accordance with
the driving condition of the compressor. As apparent from equation
III, the control valve 35 automatically controls the opening degree
such that gas pressure load obtained by multiplying the primary
pressure .DELTA.PX, or PdH-PdL, and a secondary pressure .DELTA.PY,
or PdL-Pc, by the corresponding pressure receiving area and the
total load of the force f1 and f2 of the electromagnetic force F
and the spring 123, 128 are balanced. The operating rod 103 is a
second pressure sensing member, which is displaced in accordance
with the pressure difference between the pressure PdL and the crank
pressure Pc.
[0048] In the control valve 35 according to the first embodiment
having the above mentioned operating characteristics, the opening
degree is determined in the following manner under each
circumstance. When no current is supplied to the coil 129, or when
the duty ratio is zero percent, the force of the return spring 123
(more specifically, the force of f1-f2) becomes dominant and
positions the operating rod 103 at the lowermost position shown in
FIG. 2. The valve body 106 is spaced from the valve seat 119 by the
greatest distance, which fully opens the inlet valve portion 101.
When a current of the minimum duty ratio within a variable range of
the duty ratio is supplied to the coil 129, the upward
electromagnetic force F is at least greater than the downward force
f2 of the return spring 123. The sum of the upward electromagnetic
force F generated by the solenoid portion 102 and the upward force
f2 of the shock-absorbing spring 128 acts against the sum of the
downward force f1 of the return spring 123 and the downward force
based on the secondary pressure .DELTA.PY and the primary pressure
.DELTA.PX. As a result, the position of the valve body 106 relative
to the valve seat 119 is determined such that equation III is
satisfied, which determines the opening degree of the control valve
35. Accordingly, the flow rate of gas to the crank chamber 15
through the supply passage is determined. Then, the crank pressure
Pc is adjusted in accordance with the relationship between the flow
rate of gas through the supply passage and the flow rate of gas
flowing out from the crank chamber 15 through the bleed passage
33.
[0049] As shown in FIGS. 1 and 4, the pulley 17 includes an
upstream rotating body, which is an upstream pulley member 17A, and
a downstream rotating body, which is a downstream pulley member
17B. The downstream pulley member 17B is formed by a first
cylinder, which is a first inner cylinder 17C, and a first
disk-like portion 17D, which is integrally formed with the front
end of the first inner cylinder 17C and extends radially outward.
The upstream pulley member 17A is formed by an outer cylinder 17E,
about which the belt 18 is wound, a second cylinder, which is a
second inner cylinder 17F, and a second disk-like portion 17G,
which is integrally formed with the outer cylinder 17E and the
second inner cylinder 17F to couple the outer cylinder 17E and the
second inner cylinder 17F with each other.
[0050] Breakable members, which are columnar power transmission
pins 17H (only two are shown) are secured to the peripheral portion
of the first disk-like portion 17D at equal angular intervals about
the axis of the first disk-like portion 17D. The power transmission
pins 17H are fitted in through holes formed in the peripheral
portion. The power transmission pins 17H project rearward and
extends substantially parallel to the axial direction of the drive
shaft 16. The power transmission pins 17H form a discontinuing
mechanism on a power transmission path between the engine E and the
drive shaft 16 for preventing excessive power transmission. In the
first embodiment, the power transmission pins 17H are formed by
sintered metal. The sintered metal has the fatigue ratio
.sigma..sub.W/.sigma..sub.B of approximately 0.5. .sigma..sub.W
represents the fatigue strength and .sigma..sub.B represents the
tensile strength.
[0051] An annular elastic member, which is a rubber damper 17J is
attached to the front end of the outer cylinder 17E of the upstream
pulley member 17A to extend along the circumferential direction of
the upstream pulley member 17A. Through holes 17K are formed in the
rubber damper 17J at positions corresponding to the power
transmission pins 17H. Each power transmission pin 17H is fitted in
one of the through holes 17K. Therefore, in the pulley 17 according
to the first embodiment, the power that is transmitted to the
upstream pulley member 17A via the belt 18 is transmitted to the
downstream pulley member 17B via the rubber damper 17J and the
power transmission pins 17H. That is, the rubber damper 17J and the
power transmission pins 17H are located on the power transmission
path between the upstream pulley member 17A and the downstream
pulley member 17B.
[0052] In the first embodiment, the upstream pulley member 17A, the
downstream pulley member 17B, the power transmission pins 17H, and
the rubber damper 17J form the pulley 17. The first inner cylinder
17C and the second inner cylinder 17F are substantially coaxial and
are apart from each other in the axial direction. The pulley 17 has
an internal space surrounded by the upstream pulley member 17A and
the downstream pulley member 17B.
[0053] A second rotating body, which is a hub 40 in the first
embodiment, is secured to the front end of the drive shaft 16. The
hub 40 has a cylindrical support portion 40A and a disk-like
portion 40B, which is integrally formed with the support portion
40A and extends radially outward. The support portion 40A has a
female screw portion, which is screwed to a male screw portion
formed at the front end of the drive shaft 16. The hub 40 has a
cylindrical portion 40C, which is integrally formed with the
disk-like portion 40B and extends forward from the periphery of the
disk-like portion 40B, and a substantially disk-like flange 40D,
which is integrally formed with the cylindrical portion 40C and
extends radially outward from the front end of the cylindrical
portion 40C.
[0054] The support portion 40A is located radially inward of the
inner cylinders 17C, 17F, that is, closer to the axis of the drive
shaft 16. The disk-like portion 40B is located between the inner
cylinders 17C, 17F in the axial direction of the drive shaft 16.
The cylindrical portion 40C is located radially outward of the
first inner cylinder 17C.
[0055] A one-way clutch unit 50 is located between the cylindrical
portion 40C and the first inner cylinder 17C. The one-way clutch
unit 50 includes a one-way clutch 51 and a first ball bearing,
which is a bearing 52 in the first embodiment. The bearing 52 is
located at the rear of the one-way clutch 51.
[0056] The one-way clutch unit 50 has an outer ring 53, which is
secured to the inner circumferential surface of the cylindrical
portion 40C, and an inner ring 54, which is secured to the outer
circumferential surface of the first inner cylinder 17C and is
arranged such that the inner ring 54 is surrounded by the outer
ring 53. The bearing 52 includes rolling elements, which are balls
55. The balls 55 are arranged in a line in the circumferential
direction between the outer ring 53 and the inner ring 54. The
balls 55 permit the outer ring 53 to rotate relative to the inner
ring 54.
[0057] As shown in FIGS. 6(a) and 6(b), the one-way clutch 51
includes accommodating recesses 56, which are formed in the inner
circumferential surface of the outer ring 53. The accommodating
recesses 56 are arranged at equal angular intervals about the axis
of the drive shaft 16. A power transmission surface 57 is formed on
one end (the leading end in the clockwise direction in FIG. 6(a))
of each accommodating recess 56. Each accommodating recess 56
accommodates a roller 58 the axis of which is parallel to the axis
of the drive shaft 16. Each roller 58 is movable between a position
in which the roller 58 engages with the corresponding power
transmission surface 57 (see FIG. 6(a)), and a position apart from
the engaging position (see FIG. 6(b)). A spring seat 59 is located
at the end of each accommodating recess 56 opposite to the power
transmission surface 57. A spring 60 is located between each spring
seat 59 and the corresponding roller 58 to urge the roller 58
toward the engaging position.
[0058] As shown in FIG. 6(a), when the inner ring 54 is rotated in
the direction shown by an arrow (clockwise direction) by the power
transmitted from the engine E of the vehicle via the pulley 17,
each roller 58 moves to the engaging position by the force of the
corresponding spring 60. Then, each roller 58 is engaged between
the power transmission surface 57 and the outer circumferential
surface of the inner ring 54. The outer ring 53 is thus rotated in
the same direction as the inner ring 54. Therefore, when the engine
E of the vehicle is running, power of the engine E of the vehicle
is transmitted to the drive shaft 16 via the pulley 17, one-way
clutch 51, and the hub 40 so that the drive shaft 16 is always
rotated.
[0059] When the engine E of the vehicle is stopped, that is, when
the pulley 17 is stopped, if the outer ring 53 is rotated in the
direction shown by an arrow (clockwise direction) as shown in FIG.
6(b), each roller 58 separates from the engaging position against
the force of the corresponding spring 60. Therefore, the outer ring
53 runs idle with the inner ring 54.
[0060] As shown in FIGS. 1 and 4, a support cylinder 12B projects
from the front wall of the front housing member 12 of the
compressor main body C to surround the front end of the drive shaft
16. A support 62A of a stator fixing member 62 is fitted to the
support cylinder 12B. A second ball bearing, which is a bearing 63
in the first embodiment, is located between the support 62A and the
second inner cylinder 17F of the upstream pulley member 17A. That
is, the pulley 17 is supported by the one-way clutch unit 50 and
the bearing 63, which are located axially separate from each
other.
[0061] The stator fixing member 62 has a cylindrical mounting
portion 62B for mounting a stator 61, which forms part of the motor
generator MG, and a substantially disk-like coupling portion 62C,
which couples the mounting portion 62B to the support 62A. The
coupling portion 62C is located between the inner cylinders 17C,
17F in the axial direction of the drive shaft 16 and is located at
the rear of the disk-like portion 40B. The mounting portion 62B is
located radially outward of the cylindrical portion 40C and the
second inner cylinder 17F.
[0062] The stator 61 is mounted on the outer circumferential
surface of the mounting portion 62B. The stator 61 includes a fixed
iron core and a coil, which is wound about the fixed iron core. A
rotor 64, which forms part of the motor generator MG, is secured to
the outer circumferential portion of the flange 40D. The rotor 64
is arranged about the stator 61. The rotor 64 includes a rotor core
and a rotor conductor, which is secured to the rotor core. The
motor generator MG is located in the internal space of the pulley
17.
[0063] The coil of the stator 61 is connected to a battery (not
shown) via a motor drive circuit (not shown), which includes an
inverter, converter, and the like. The motor drive circuit controls
whether to store the power generated by the coil in the battery or
to supply power from the battery to the coil in accordance with a
command from a motor control unit, which is not shown.
[0064] When the battery needs to be charged while the engine E is
running, the motor control unit controls the motor drive circuit
such that the motor generator MG functions as an induction
generator and the motor generator MG generates electric power. When
the rotor 64 is rotated with the hub 40 by the power transmission
from the engine E of the vehicle, electricity is generated at the
coil and the electricity is stored in the battery via the motor
drive circuit.
[0065] When the battery need not be charged while the engine E of
the vehicle is running, the motor control unit controls the motor
drive circuit such that the motor generator MG does not generate
electricity. This is achieved when the motor control unit commands
the motor drive circuit not to supply exciting current to the motor
generator MG, which is formed by an induction machine. In this
state, magnetic force does not act between the stator 61 and the
rotor 64. Therefore, although the rotor 64 is rotated by the power
from the engine E of the vehicle, energy loss, such as heat
generation due to iron loss of the stator 61 and the rotor 64, is
not caused. Although the rotor 64 is rotated by power from the
engine E of the vehicle, torque fluctuation of the drive shaft 16
based on the magnetic force is not caused.
[0066] If it is determined, based on the external information, that
air conditioning (cooling) is necessary while the engine E of the
vehicle is stopped, the motor control unit controls the motor drive
circuit such that the motor generator MG functions as an induction
motor. That is, rotational force is generated at the rotor 64 by
the power supplied from the motor drive circuit to the coil. The
rotational force is transmitted to the drive shaft 16 via the hub
40. Accordingly, the vehicle passenger compartment can be air
conditioned while the engine E of the vehicle is stopped.
[0067] When the motor generator MG functions as a motor and rotates
the hub 40, the one-way clutch 51 operates to stop the power
transmission between the hub 40 and the pulley 17. Thus, the power
of the motor generator MG is prevented from being transmitted to
the engine E of the vehicle.
[0068] In the first embodiment, drive force transmitted to the
upstream pulley member 17A from the engine E of the vehicle is
transmitted to the downstream pulley member 17B via the rubber
damper 17J and the power transmission pins 17H. Since the rubber
damper 17J is located on the power transmission path between the
upstream pulley member 17A and the downstream pulley member 17B,
misalignment between the axis of the bearing 52 and the axis of the
bearing 63 is absorbed. That is, the deformation of the rubber
damper 17J reduces stress generated on the bearings 12A, 52, and 63
due to the misalignment. The rubber damper 17J prevents the
rotation vibration of the drive shaft 16 caused by the compression
reaction force in the compression mechanism, or the torque
fluctuation, from being transmitted from the downstream pulley
member 17B to the upstream pulley member 17A.
[0069] Due to the operation of the one-way clutch 51 that permits
transmission of power only in one rotational direction, the
rotation vibration that acts in the other direction is not
transmitted from the hub 40 to the pulley 17.
[0070] In the first embodiment, when the magnitude of the
transmission torque between the upstream pulley member 17A and the
downstream pulley member 17B is not large enough to affect the
engine E of the vehicle, that is, during the normal power
transmission state, power transmission from the engine E of the
vehicle to the drive shaft 16 is continued. However, if an
abnormality (such as a deadlock) occurs in the compressor main body
C and the transmission torque exceeds an acceptable value, the
power transmission pins 17H are broken by the excessive load, which
stops power transmission from the upstream pulley member 17A to the
downstream pulley member 17B. Accordingly, the engine E of the
vehicle is prevented from being adversely affected by the excessive
transmission torque.
[0071] The first embodiment provides the following advantages.
[0072] (1) The one-way clutch 51 is located on the power
transmission path between the first inner cylinder 17C of the
pulley 17 and the cylindrical portion 40C of the hub 40. Therefore,
for example, as compared to a case where the electromagnetic clutch
is located on the power transmission path between the pulley 17 and
the hub 40, the size and the weight of the mechanism for
selectively discontinuing power transmission between the drive
shaft 16 and the pulley 17 are reduced. This facilitates reducing
the size of the power transmission mechanism PT and reducing the
size and weight of the compressor that includes the power
transmission mechanism PT. Since a controller for selectively
connecting and disconnecting the electromagnetic clutch is
unnecessary, the structures of the power transmission mechanism PT
and the compressor are simplified. This reduces the cost of the
power transmission mechanism PT and the compressor.
[0073] (2) The motor generator MG is located in the internal space
of the pulley 17 surrounded by the upstream pulley member 17A and
the downstream pulley member 17B. Therefore, the size of the power
transmission mechanism PT is reduced by effectively using the
internal space.
[0074] (3) The first inner cylinder 17C and the second inner
cylinder 17F are apart from each other in substantially the axial
direction of the pulley 17. Therefore, for example, as compared to
a case where the first inner cylinder 17C and the second inner
cylinder 17F are located at the same axial position, a space for
accommodating the motor generator MG is easily obtained.
[0075] (4) The first inner cylinder 17C and the second inner
cylinder 17F, which are apart from each other in the axial
direction, are supported by the bearings 52 and 63, respectively.
Therefore, when an external force is applied to the pulley 17, the
pulley 17 is prevented from being inclined with respect to the axis
of the drive shaft 16. Thus, partial wear of each part of the
pulley 17 and bad engagement of the one-way clutch 51 caused by the
inclination of the pulley 17 are suppressed.
[0076] (5) The discontinuing mechanism is located on the power
transmission path between the engine E of the vehicle and the drive
shaft 16. Therefore, for example, although an abnormality, such as
a deadlock, occurs in the compressor main body C, an excessive load
is prevented form being applied to the engine E of the vehicle.
[0077] (6) The power transmission pins 17H located on the power
transmission path between the upstream pulley member 17A and the
downstream pulley member 17B break when the transmission torque is
excessive to stop the power transmission. That is, in the first
embodiment, the power transmission between the upstream rotating
body and the downstream rotating body can be disconnected by
breaking the breakable members, which are the power transmission
pins 17H.
[0078] (7) The power transmission pins 17H are formed by sintered
metal. Since the sintered metal has a relatively low ductility, the
magnitude of the transmission torque required for breaking the
power transmission pins 17H is easily set. The fatigue ratio
.sigma..sub.W/.sigma..sub.B of the sintered metal is relatively
easily maintained at a high value. Therefore, during the normal
power transmission state, the durability against repeated stress
that acts on the power transmission pins 17H is maintained
relatively high, and the balance between the durability and the
transmission torque amount for breaking the power transmission pins
17H is easily optimized. Therefore, the power transmission pins 17H
reliably transmit power during the normal power transmission state
showing satisfactory durability and reliably blocks power when the
transmission torque becomes excessive.
[0079] (8) The breakable members are simple pins 17H. Therefore,
the structures of the breakable members and the through holes 17K
are simplified, which facilitates the manufacture and reduces the
cost of the power transmission mechanism PT.
[0080] (9) The elastic member, which is the rubber damper 17J, is
located on the power transmission path between the upstream pulley
member 17A and the downstream pulley member 17B. Therefore,
deformation of the rubber damper 17J reduces the stress generated
on the bearings 12A, 52, and 63 caused by the misalignment between
the axis of the bearing 52 and the axis of the bearing 63 due to
the manufacturing tolerance and the like. Therefore, the durability
of the compressor is improved.
[0081] (10) The rubber damper 17J, which serves as a buffer member,
reduces the torque fluctuation that is transmitted from the
downstream pulley member 17B to the upstream pulley member 17A.
[0082] (11) The bearing 52 is formed by balls 55, which are
arranged in a line in the circumferential direction between the
outer ring 53 and the inner ring 54. Therefore, for example, as
compared to a structure in which balls 55 are arranged in the axial
direction of the bearing 52, the axial length of the bearing 52 is
reduced.
[0083] (12) The compressor main body C reduces the discharge
displacement per one rotation of the drive shaft 16 to
substantially zero. Since the discharge displacement of the
compressor main body C during rotation of the drive shaft 16 is
reduced to substantially zero, unnecessary load is hardly applied
to the engine E of the vehicle when air conditioning is not
required.
[0084] (13) According to the control valve 35 of the first
embodiment, the discharge displacement (flow rate of refrigerant)
of the compressor main body C per unit time, which greatly affects
the load torque of the compressor main body C, is controlled
directly from the outside. Also, for example, the flow rate of
refrigerant is controlled to be less than or equal to a
predetermined amount in an accurate and responsive manner without
using a refrigerant flow rate sensor or the like.
[0085] A second embodiment of the present invention will now be
described with reference to FIGS. 5(a) and 5(b). A compressor of
the second embodiment has the same structure as the first
embodiment except that mainly the downstream pulley member and the
structure of the coupling portion between the downstream pulley
member and the upstream pulley member are modified. Therefore, like
or the same reference numerals are given to those components that
are like or the same as the corresponding components of the first
embodiment, and detailed explanations are omitted.
[0086] As shown in FIGS. 5(a) and 5(b), a downstream rotating body,
which is a downstream pulley member 70 in the second embodiment,
has a first inner cylinder 70A, which is fitted in the inner ring
54 of the one-way clutch unit 50. The downstream pulley member 70
also has an outer ring 70C, which is formed integrally with the
first inner cylinder 70A via breakable members, which are spokes
70B in the second embodiment. The spokes 70B (four in the second
embodiment) extend from the first inner cylinder 70A radialy toward
the outer ring 70C. The spokes 70B couple the first inner cylinder
70A to the outer ring 70C to permit power transmission.
[0087] In the second embodiment, the downstream pulley member 70,
which includes the integrally formed first inner cylinder 70A, the
spokes 70B, and the outer ring 70C, is made by sintered metal. The
sintered metal is set such that the fatigue ratio
.sigma..sub.W/.sigma..sub.B is maintained approximately at 0.5.
[0088] The annular elastic member, which is the rubber damper 71,
is located between the rear end of the outer ring 70C and the front
end of the outer cylinder 17E of the upstream pulley member 17A.
The rubber damper 71 is fixed to the outer ring 70C and the outer
cylinder 17E.
[0089] In the second embodiment, the drive force transmitted from
the engine E of the vehicle to the upstream pulley member 17A is
transmitted to the hub 40 via the rubber damper 71, the outer ring
70C, and the spokes 70B. That is, the rubber damper 71 and the
spokes 70B are located on the power transmission path between the
upstream pulley member 17A and the hub 40. The rubber damper 71
absorbs misalignment between the axis of the bearing 52 and the
axis of the bearing 63. The rubber damper 71 prevents the torque
fluctuation from being transmitted from the downstream pulley
member 70 to the upstream pulley member 17A.
[0090] In the second embodiment, when the transmission torque
between the outer ring 70C of the downstream pulley member 70 and
the first inner cylinder 70A is not large enough to affect the
engine E of the vehicle, that is, during normal power transmission
state, the power transmission from the engine E to the drive shaft
16 is continued. However, if an abnormality (such as a deadlock)
occurs in the compressor main body C and the transmission torque
exceeds the acceptable value, the spokes 70B are broken by the
excessive load, which stops the power transmission from the
upstream pulley member 17A to the hub 40. Accordingly, the engine E
of the vehicle is prevented from being adversely affected by the
excessive transmission torque.
[0091] The second embodiment provides the following advantage in
addition to the advantages (1) to (7) and (9) to (13) of the first
embodiment.
[0092] (14) Since the power transmission can be stopped by breaking
the downstream pulley member 70, a breakable member formed by a
member other than the downstream pulley member 70 need not be
provided. Therefore, a procedure for mounting the breakable member
formed by another member to the downstream pulley member 70 is
omitted.
[0093] 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 invention may be
embodied in the following forms.
[0094] In the first embodiment, the pulley 17 has the upstream
pulley member 17A and the downstream pulley member 17B, and the
breakable members, which are the power transmission pins 17H, are
located on the power transmission path between the upstream pulley
member 17A and the downstream pulley member 17B. On the contrary,
the hub 40 may have an upstream rotating body and a downstream
rotating body, and a breakable member may be located on a power
transmission between the rotating bodies.
[0095] In the second embodiment, the downstream pulley member 70 is
formed of sintered metal. The power transmission is stopped when
the downstream pulley member 70 is broken. However, the hub 40 may
be made of sintered metal, and the power transmission may be
stopped when the hub 40 is broken.
[0096] The compressor according to the first and second embodiments
includes the discontinuing mechanism on the pulley 17 (70). On the
contrary, the discontinuing mechanism may be located on a power
transmission path between the pulley 17 (70) and the hub 40, such
as a power transmission path between the pulley 17 and the one-way
clutch unit 50, or between the one-way clutch unit 50 and the hub
40. The discontinuing mechanism may be located on the one-way
clutch unit 50. The discontinuing mechanism may be located on a
power transmission path between the hub 40 and the drive shaft
16.
[0097] In the above embodiments, the fatigue ratio
.sigma..sub.W/.sigma..s- ub.B of the sintered metal that form the
breakable member is maintained approximately at 0.5. However, the
fatigue ratio may be varied as long as the breakable member can be
broken when the excessive transmission torque is applied to the
breakable member.
[0098] In the above embodiments, the breakable member is made by
sintered metal. However, the breakable member may be formed by
low-carbon steel. The fatigue ratio .sigma..sub.W/.sigma..sub.B of
low-carbon steel is relatively easy to maintain at a relatively
high value (approximately 0.5). Therefore, during the normal power
transmission state, the durability against the repeated stress that
acts on the breakable member is maintained relatively high, and the
balance between the durability and the transmission torque amount
for breaking the power transmission pins 17H is easily
optimized.
[0099] In the above embodiments, the breakable member is made of
metal. However, the breakable member may be made of resin or
ceramics as long as the breakable member can be broken at a
predetermined transmission torque when an excessive transmission
torque is applied to the breakable member.
[0100] In the first embodiment, the power transmission pins 17H may
be formed integrally with the downstream pulley member 17B. When
the downstream pulley member 17B, to which the power transmission
pins 17H are integrally formed, is made by breakable material such
as sintered metal, the power transmission can be stopped by
breaking of the portion corresponding to the power transmission
pins 17H.
[0101] In the first embodiment, the power transmission pins 17H are
fixed to the downstream pulley member 17B and coupled to the
upstream pulley member 17A via the rubber damper 17J. On the
contrary, the power transmission pins 17H may be fixed to the
upstream pulley member 17A and coupled to the downstream pulley
member 17B via the rubber damper 17J.
[0102] In the first embodiment, the power transmission pins 17H may
be attached to the downstream pulley member 17B via a tubular
elastic member such as a rubber damper. That is, the power
transmission pins 17H may be coupled to both the upstream pulley
member 17A and the downstream pulley member 17B via the elastic
member.
[0103] In the first embodiment, all the power transmission pins 17H
are coupled to one rubber damper 17J. However, each power
transmission pin 17H may be coupled to separate rubber damper. For
example, the power transmission pins 17H may be formed as shown in
FIG. 7. A tubular elastic member having a circular cross-section,
which is a rubber damper 80, is fitted to the rear end of each
power transmission pin 17H. Each rubber damper 80 is accommodated
in a damper accommodating recess 81 formed in the front end of the
outer cylinder 17E of the upstream pulley member 17A. In this case,
as compared to the first embodiment, the amount of rubber material
used for forming the rubber damper is reduced.
[0104] The cross-sections of the power transmission pins 17H and
the hole of the rubber damper 17J (71, 80) need not be circular.
The cross-section of the outline of the rubber damper 80 shown in
FIG. 7, in particular, need not be circular.
[0105] In the first and second embodiments, the breakable member
and the elastic member are separate members. However, the elastic
member may also serve as the breakable member. For example, in the
first embodiment, the upstream pulley member 17A and the downstream
pulley member 17B may be coupled to each other via only the rubber
damper 17J. In this case, if an excessive transmission power is
applied to the rubber damper 17J, the power transmission is stopped
when the rubber damper 17J is pulled apart.
[0106] In the above embodiments, the elastic member is located on
the pulley 17 but may be located on the hub 40. For example, the
elastic member may be located on a power transmission path between
the one-way clutch unit 50 and the drive shaft 16. The elastic
member may also be located on a power transmission path between the
pulley 17 and the one-way clutch unit 50, or between the one-way
clutch unit 50 and the hub 40. The elastic member may be located on
the power transmission path between the hub 40 and the drive shaft
16.
[0107] The elastic member may be formed of elastic material other
than rubber such as elastomer.
[0108] The elastic member for absorbing misalignment between the
axis of the bearing 52 and the axis of the bearing 63 may be
omitted.
[0109] In the above embodiments, the discontinuing mechanism is
formed by a breakable member. However, the discontinuing mechanism
need not be a breakable member. For example, the discontinuing
mechanism may be formed by a coupling member that operably couples
the upstream rotating body to the downstream rotating body and
selectively engages with and disengages from one of the rotating
bodies.
[0110] The structure of the one-way clutch 51 may be modified as
long as the power transmission from the pulley 17 to the drive
shaft 16 is permitted and the power transmission from the motor
generator MG to the pulley 17 is prevented.
[0111] A motor generator that utilizes a permanent magnet may be
employed instead of the motor generator MG that is formed by an
induction machine. The motor generator that uses a permanent magnet
easily obtains a great output as compared to the motor generator
that is formed by an induction machine.
[0112] An electric part that functions only as a motor may be
employed instead of the electric part that functions as a motor and
a generator.
[0113] The motor generator MG need not be located inside the
internal space of the pulley 17 but may be located outside the
pulley 17.
[0114] The first inner cylinder 17C (70A) and the second inner
cylinder 17F may be located at substantially the same position in
the axial direction.
[0115] The bearing 52 may have multiple lines of balls 55.
[0116] In the above embodiments, the position of the valve body 106
is adjusted by applying the pressure in the pressure sensing
chamber 114 to the movable wall 120 accommodated in the pressure
sensing chamber 114. On the contrary, the pressure in the pressure
sensing chamber 114 may be applied to a pressure sensing member
such as a bellows or a diaphragm located inside the pressure
sensing chamber 114 to adjust the axial position of the valve body
106.
[0117] In the above embodiments, the control valve 35 is designed
such that the position of the valve body 106 is automatically
changed to vary the displacement to cancel the fluctuation of the
pressure difference between two pressure monitoring points P1, P2
located in the refrigerant circuit. On the contrary, for example,
the position of the valve body 106 may be changed in accordance
with the pressure of one pressure monitoring point located in the
refrigerant circuit. Also, for example, the position of the valve
body 106 may be changed in accordance with a command from the
outside.
[0118] In the above embodiments, the control valve 35 is designed
such that the criteria of the positioning operation of the valve
body 106 can be changed by an external control. On the contrary,
for example, the control valve 35 may be designed to perform only
the automatic positioning operation of the valve body 106 without
being controlled from the outside.
[0119] Instead of providing the control valve 35 in the supply
passage, a control valve may be located in the bleed passage 33. In
this case, the control valve in the bleed passage adjusts the flow
rate of refrigerant from the crank chamber 15 to the suction
chamber 27 to control the crank pressure Pc. That is, the control
valve may be located at any place as long as the control valve is
located in at least one of the supply passage and the bleed passage
connected to the crank chamber 15. The discharge chamber 28 and the
suction chamber 27 are pressure zones, which are exposed to
pressure that is different from the crank pressure Pc. The supply
passage and the bleed passage are pressure control passages, which
connect the pressure zone to the control pressure zone, which is
the crank chamber 15.
[0120] The single-sided compressor main body C, which causes
single-headed pistons to perform the compression operation, may be
changed to a both-sided compressor main body, which causes
double-headed pistons to perform the compression operation in
cylinder bores formed on both sides of a crank chamber.
[0121] The present invention may be embodied in a compressor that
has a drive plate that is rotatably supported by the drive shaft to
wobble with respect to the drive shaft. For example, the present
invention may be embodied in a wobble plate type compressor.
[0122] The discharge displacement per one rotation of the drive
shaft 16 may be greater than zero at the minimum displacement of
the compressor main body C.
[0123] The compressor main body C may be changed to a fixed
displacement compressor main body in which the stroke of the
pistons 25 is constant.
[0124] The present invention may be embodied in rotary compressors
such as a scroll compressor.
[0125] The first rotating body, which is the pulley 17, may be
changed to, for example, a sprocket or a gear.
* * * * *