JP3089816B2 - Swash plate type variable displacement compressor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention relates to a swash Itashiki variable displacement compressor that is used to compress such refrigerant gas, for example in vehicle air-conditioning system.

[0002]

2. Description of the Related Art Conventionally, as a compressor for vehicle air conditioning , a piston reciprocates in response to both suction pressure and discharge pressure .
Angle friendly to the crank chamber pressure, as the inclination angle of the rocking swash plate as the swash plate is varied allowed to increase or decrease the displacement of the compressor (flow rate) is configured to control relative suction pressure for
There is a variable displacement compressor of the swash plate type. (JP-A-58-15)
In this compressor, when the suction pressure decreases due to a decrease in the cooling load or a high-speed rotation, the bellows of the discharge capacity control mechanism extends due to a fluctuation in the balance between the suction pressure and the atmospheric pressure, and operates the valve mechanism to operate the suction chamber. The area of the bleed passage between the crank chambers is reduced. Further, by opening the air supply passage between the discharge chamber and the crank chamber by another valve mechanism, the pressure in the crank chamber is increased to increase the differential pressure between the crank chamber pressure and the suction pressure. That is, the pressure acting on the back surface of the piston is increased, whereby the stroke of the piston is reduced, and the inclination angle of the swinging swash plate is reduced to prevent the suction pressure from lowering and at the same time to reduce the capacity.

As the discharge capacity control mechanism, the following two mechanisms have been proposed. The control mechanism shown in FIG. 8 connects a valve casing 41 in the middle of a bleed passage 21 communicating the crank chamber 2a and the suction chamber 4a, and a pressure chamber 42 inside the valve casing 41.
A valve hole 43 and a valve chamber 44 are formed. Further, at the end of the casing 41, a valve body 46 is supported via a diaphragm 45, and another casing 4 attached to the casing 41 is provided.
7, a constant pressure chamber 48 is formed, and a spring 49 is connected to the constant pressure chamber 4.
8 and closed by a lid 50. The valve body 46 is always urged by a spring 49 in a direction to close the valve hole 43. The opening and closing of the valve body 46 is controlled by the fluctuation of the suction pressure Ps, and the crank chamber 2a is moved from the suction chamber 4a
By controlling the flow rate of the refrigerant gas to the controller, the rise of the crank chamber pressure Pc is controlled.

The control mechanism shown in FIG. 9 has, in addition to the control mechanism shown in FIG. 8, a valve chamber 51 provided in a supply passage 54 communicating the discharge chamber 4b and the crank chamber 2a. Accommodates a ball valve 52. Also, the valve body 46
The ball valve 52 is moved by the operating rod 53 connected to the spring 5.
5 can be opened against the urging force. The amount of gas supplied from the discharge chamber 4b to the crank chamber 2a through the air supply passage 54 is controlled by the fluctuation of the crank chamber pressure Pc so that the crank chamber pressure Pc does not decrease.

[0005]

In the above two conventional displacement control mechanisms, the higher the crank chamber pressure Pc, the higher the valve body 4 is.
6 easily opens the valve hole 43, and the refrigerant gas easily moves from the crank chamber 2a to the suction chamber 4a. Therefore, the differential pressure ΔP _cs between the crank chamber pressure Pc and the suction pressure Ps (Pc−Ps)
Is larger, the valve body 46 is easier to open, that is, the valve body 46 is opened at a lower suction pressure Ps. This is the differential pressure ΔP
_cs increases, the set value P _so the suction pressure Ps required to open the valve member 46 which means that lower.

In the conventional discharge capacity control mechanism, when the operation is shifted from the normal operation to the high-speed operation in a state where the cooling load is high, the inclination angle of the swing swash plate is large and the discharge capacity is large, the swing in the crank chamber 2a is increased. There is a problem that the dynamic swash plate is easily hunted and the capacity control is poor. That is, the larger the displacement of the compressor and the larger the inclination angle of the swash plate, the greater the reciprocating inertia force acting on it. Since the reciprocating inertia force of the swinging swash plate increases and the moment in the capacity increasing direction increases and a higher crank chamber pressure Pc is required for stabilization, the suction pressure Ps does not change. The pressure Pc does not rise and the state becomes unstable. For this reason, the suction pressure Ps fluctuates in small increments up and down from the set value P _{so as} to cause capacity control failure. Further, the reciprocating inertial force of the swinging swash plate acts in a direction to increase the inclination angle of the swash plate,
In addition, this tendency becomes greater during high-speed operation.

[0007] The above-mentioned capacity control failure occurs to some extent even if the discharge capacity of the compressor is small, but in this case, it is not so problematic, and the discharge capacity is maximum and becomes remarkable at high speed operation.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art, and to reduce the discharge capacity and suppress the hunting operation in the front-rear direction due to the reciprocating inertial force of the swash plate when the compressor is operating at high speed. to provide a swash Itashiki variable compressor that can <br/> in making it possible to improve the capacity controllability and.

[0009]

In order to achieve the above object, the present invention comprises a suction chamber, a discharge chamber and a crank chamber,
The swash plate for reciprocating the piston relative to the drive shaft tiltably mounted, it changes the inclination angle of the front Kihasu plate according to a differential pressure between the crank chamber pressure and suction pressure, controls the discharge capacity In the swash plate type variable displacement compressor, the crank chamber and the suction chamber are communicated by a bleed passage, and a valve chamber and a valve hole are provided in the middle of the bleed passage. A valve body that opens and closes a valve hole is housed, and the valve body is constantly urged to an open position by an urging member. When the suction pressure is sensed and the suction pressure is reduced, the valve body is closed. Means of providing pressure-sensitive control means for controlling is adopted.

[0010]

According to the present invention, when the compressor is started in a state where the cooling load is large, the suction pressure is high, the valve body has the valve hole opened, and the swash plate is displaced to the maximum displacement position, the suction is started. The pressure gradually decreases as the cooling load decreases. Further, the gas blow-by from the compression chamber to the crank chamber acts in a direction to increase the pressure in the crank chamber. However, since this gas flows from the crank chamber to the suction chamber via the bleed passage, the crank chamber pressure and the suction pressure are reduced. Does not change, so that the operation is continued at the large capacity where the inclination angle of the swash plate is the maximum.

When the load on the cooling device is reduced and the suction pressure decreases to a set value, the valve hole closes the valve hole, and the supply of gas from the crank chamber to the suction chamber is stopped. The pressure in the room is increased by the blow-by gas, the inclination angle of the swash plate is reduced, and the discharge capacity of the compressor is reduced in accordance with the reduction of the cooling load.

When the compressor is switched from a normal operation state to a high-speed rotation in a large capacity state, the suction pressure decreases and the amount of gas blow-by from the compression chamber increases, so that the crank chamber pressure and the suction pressure are reduced. Differential pressure increases. This crank chamber pressure acts as a biasing force in the valve chamber in the direction to close the valve body, and the reduction in suction pressure also acts in the direction to close the valve body, so that the rotational speed of the compressor increases. As the differential pressure increases, the valve body is more strongly pressed in the closing direction, and the set value of the suction pressure for opening the valve body increases. Therefore, even if the rotational speed of the compressor increases, the valve body does not open and the crank chamber pressure easily increases, and the pressure difference between the crank chamber pressure and the suction pressure increases, and the inclination angle of the swash plate increases. The discharge capacity is reduced, the reciprocating inertial force of the swash plate during high-speed operation is reduced, and the capacity control performance is improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, a front housing 2 is joined and fixed to a front end of the cylinder block 1, and a rear housing 4 forming a suction chamber 4a and a discharge chamber 4b is joined and fixed to a rear end face via a valve plate 3. I have. The valve plate 3 has a suction chamber 4a.
A suction valve mechanism 5 capable of sucking refrigerant gas is provided in a compression chamber in a cylinder bore 1a formed in the cylinder block 1, and a discharge valve mechanism 6 capable of discharging refrigerant gas compressed in the cylinder bore 1a to a discharge chamber 4b is provided. Have been.

A drive shaft 7 is supported by bearings 8 at the center of the cylinder block 1 and the front housing 2. A rotary driving body 9 is provided at an intermediate portion of the driving shaft 7.
Are fitted and fixed, and an arm 10 is integrally formed on the outer periphery thereof so as to protrude. Also, a long hole 10 formed in the arm 10 is formed.
A rotary support 12 is supported by a through a connecting pin 11 so as to be swingable in the front-rear direction and to be rotatable synchronously with the drive shaft 7. A swash plate is provided on the boss 12a of the rotary support 12.
Rocking swash plate 13 and is relatively rotatably and tiltably supported in the longitudinal direction in advance position by the anti-rotation rod 14 which is fixed to the cylinder block 1 and the front housing 2.

A sleeve 15 is supported on the drive shaft 7 so as to be able to reciprocate in the axial direction. The sleeve 15 is connected to a boss 12 a of the rotary support 12 by a connecting pin 16.

The sleeve 15 is always oscillated by a spring 17 mounted on the drive shaft 7 and a rotary support 12.
Is biased to a position where the inclination angle is maximized. The swinging swash plate 13 is connected to a plurality of pistons 18 housed in the cylinder bore 1a via piston rods 19, respectively.

Therefore, when the drive shaft 7 is rotated and the rotary drive 9, the connecting pin 11, and the rotary support 12 are integrally rotated, the swing swash plate 13 swings back and forth without rotating. The piston 18 is reciprocated in the cylinder bore 1a via the piston rod 19. Therefore, the refrigerant gas sucked from the suction chamber 4a is compressed in the cylinder bore 1a and then discharged to the discharge chamber 4b. At this time, the cylinder bore 1a
Inside, the pressure Pc in the crank chamber 2a increases due to blow-by gas leaking from the outer peripheral surface of the piston 18 during compression, and this is adjusted by a pressure control valve 22 described below.

The pressure control valve 22 will now be described. The crank chamber 2a and the suction chamber 4a are formed by a bleed passage 2 formed in the cylinder block 1, the valve plate 3 and the rear housing 4.
1 communicates. A pressure control valve 22 is interposed in the middle of the bleed passage 21. This pressure control valve 22
Has a casing 23 fitted in the mounting hole 4c of the rear housing 4 as shown in FIG. This casing 2
3, a valve chamber 24, a valve hole 25, and a spring chamber 2 communicating with the valve hole 25 via a bleed passage 21 communicating with the crank chamber 2a.
6 are formed in that order. As shown in FIG. 1, a head 27a of a valve body 27 is accommodated in the valve chamber 24, and a rod portion 27b of the valve chamber 27 is inserted into a through hole 2 formed in a casing 23.
3a. A spring 28 for urging the valve body 27 in the opening direction is accommodated in the spring chamber 26.

Further, a diaphragm 29 is fixedly joined to an end of the casing 23 together with a casing 30, and a constant pressure chamber 31 is formed in the casing 30. The spring 32 housed in the constant pressure chamber 31 is pressed by the lid 33 toward the diaphragm 29, and the urging force of the spring 32 urges the valve body 27 in the closing direction via the rod portion 27b. The pressure-sensitive chamber 34 formed on the opposite side of the diaphragm 29 from the constant-pressure chamber 31 communicates with the suction chamber 4 a via a passage 35.

In this embodiment, the diaphragm 29, casing 30, constant pressure chamber 31, spring 32, lid 3
3. Pressure sensing means for sensing the suction pressure Ps of the valve body 27 by the pressure sensing chamber 33 and the spring 28, and controlling the valve body 27 in the closing (opening) direction when the suction pressure Ps decreases (rises). K.

Next, the operation of the swash plate type variable displacement compressor constructed as described above will be described. Now, in FIG. 2, in a state where the cooling load is large, the suction pressure Ps is high, the valve body 27 has the valve hole 25 opened, and the swinging swash plate 13 is displaced to the maximum (100%) capacity position. When the compressor is started, the suction pressure Ps gradually decreases as the cooling load decreases. The gas blow-by from the compression chamber in the cylinder bore 1a to the crank chamber 2a acts in a direction to increase the pressure Pc of the crank chamber. This gas flows from the crank chamber 2a to the suction chamber 4a via the bleed passage 21. Therefore, the differential pressure ΔPcs between the crank chamber pressure Pc and the suction pressure Ps
Does not change, so that the operation is continued at the large capacity where the inclination angle of the swash plate 13 is the maximum.

[0022] Then, the load of the cooling device is reduced, the suction pressure Ps is reduced to the set value P _so, since the valve hole 25 is closed by the valve body 27, the supply of gas from the crank chamber 2a to the suction chamber 4a Is stopped. For this reason, the pressure Pc in the crank chamber 2a is increased by the blow-by gas, the inclination angle of the swash plate 13 is reduced, and the discharge capacity of the compressor is reduced in accordance with the reduction of the cooling load.

When the compressor in the large capacity state is switched from the normal operation state to the high speed rotation, the suction pressure Ps decreases and the amount of gas blow-by from the compression chamber in the cylinder bore 1a increases to increase the crank chamber pressure. The pressure difference ΔP _cs between Pc and suction pressure Ps increases. The crank chamber pressure Pc acts as a biasing force in the valve chamber 24 in the direction to close the valve body 27, and the decrease in the suction pressure Ps also acts in the direction to close the valve body 27, so that the compressor Revolution N
As the differential pressure ΔP _cs increases and the differential pressure ΔP _cs increases, the valve body 27 is strongly pressed in the closing direction, and the set value P _so of the suction pressure Ps for opening the valve body 27 increases as shown in FIG. become. Therefore, when the inclination angle of the swinging swash plate 13 is maximized and the compressor is operated with a large capacity, even if the rotation speed N increases, the valve body 27 is not opened and the crank chamber pressure Pc Is easy to rise. For this reason, the differential pressure ΔP _cs between the crank chamber pressure Pc and the suction pressure Ps increases, the inclination angle of the swing swash plate 13 decreases, the discharge capacity decreases, and the reciprocating inertial force of the swing swash plate 13 during high-speed rotation increases. It is reduced and the capacity control performance is improved.

That is, as shown in FIG.
After operating at 0% capacity, increasing the number of revolutions N results in 100%
The suction pressure Ps decreases along the capacity curve. Then, when the suction pressure Ps decreases to the set value _Pso , the valve body 27 is closed, the flow of the refrigerant gas from the crank chamber 2a to the suction chamber 4a is prevented, and the differential pressure ΔP _CS is increased. As shown by the straight line L, the set value P _so of the suction pressure Ps increases in proportion to the rotation speed N. Accordingly, when the rotation speed N increases, the discharge capacity is sequentially reduced from 100% to 90, 80, 70 based on the set value P _so indicated by the straight line L. Accordingly, as compared with the conventional example in which the set value P _so of the suction pressure Ps decreases as the rotational speed increases as shown by the broken line in FIG. As an example, the discharge capacity is 90%, the discharge capacity of the above embodiment is 70%, the capacity is reduced by 20%, the reciprocating inertial force of the oscillating swash plate 13 during high-speed rotation is reduced, and the capacity control performance is improved. I do.

In the case of the conventional example in which the set value P _so of the suction pressure Ps in FIG. 4 is low, the reciprocating inertia force of the oscillating swash plate increases when the rotational speed exceeds the high speed Nh, and the capacity increases. Of the suction pressure Ps despite the fact that a higher crank chamber pressure Pc is required to stabilize
Does not change, the crank chamber pressure Pc does not increase, and the state becomes unstable.

Next, a second embodiment of the present invention will be described with reference to FIGS. In this second embodiment, as shown in FIG. 5, a pressure sensing rod 36 is connected to the valve body 27, and the end of the rod 36 is projected into a pressure sensing chamber 37 provided at an upper part of the casing 23. The pressure-sensitive chamber 37 communicates with the discharge chamber 4b through a communication passage. Then, when the discharge pressure Pd increases, the pressure Pd of the pressure sensitive chamber 37 increases, and the rod 36 of the valve body 27 is pressed to open the valve body 27. Other configurations are the same as in the first embodiment.

[0027] Therefore, as the differential pressure [Delta] P _dc between the discharge pressure Pd and the crank chamber pressure Pc, as shown in FIG. 6 is increased, the suction pressure Ps is increased, the opening degree adjustment of the valve body 27 on the basis of the characteristic Is done. In this embodiment, as shown in FIG. 7, as the discharge pressure Pd increases, the suction pressure Ps decreases. For this reason, in an operation state where the discharge pressure Pd is high and the heat load is large, the suction pressure Ps can be reduced to increase the cooling capacity and improve the cooling down characteristics.

The present invention is not limited to the above embodiments, but can be embodied as follows. (1) In the above embodiment, the valve body 27 is urged in the opening direction by the spring 28, but this is omitted and the rod 27b of the valve body 27 and the diaphragm 29 are connected.

(2) A bellows (not shown) is used in place of the diaphragm 29.

[0030]

As described above in detail, according to the present invention, when the compressor is operating at a high speed, the discharge capacity is reduced, and the hunting operation in the front-rear direction due to the reciprocating inertial force of the swash plate is suppressed, thereby controlling the capacity. Can be improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a pressure control valve according to a first embodiment of the invention.

FIG. 2 is a longitudinal sectional view showing the entire swash plate type variable displacement compressor.

FIG. 3 is a graph showing a relationship between a differential pressure between a crankcase pressure and a suction pressure and a suction pressure.

FIG. 4 is a graph showing the relationship between the rotational speed of the compressor and the suction pressure.

FIG. 5 is a longitudinal sectional view of a pressure control valve according to a second embodiment of the present invention.

FIG. 6 is a graph showing a relationship between a suction pressure and a pressure difference between a discharge pressure and a crank chamber pressure.

FIG. 7 is a graph showing a relationship between a discharge pressure and a suction pressure.

FIG. 8 is a longitudinal sectional view showing a conventional pressure control valve.

FIG. 9 is a longitudinal sectional view showing a conventional pressure control valve.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 cylinder block, 1 a cylinder bore, 2 front housing, 2 a crank chamber, 4 rear housing, 4 a suction chamber, 4 b discharge chamber, 7 drive shaft 9 rotary drive, 12 rotary support, 13 swing swash plate, 18 piston, 21 Bleed passage, 22 pressure control valve, 24 valve chamber, 25 valve hole, 26 spring chamber, 27 valve body, 28, 32
Spring, 29 diaphragm, 31 constant pressure chamber, 34 pressure sensitive chamber, K pressure sensitive control means.

Continuation of the front page (72) Inventor Hisakazu Kobayashi 2-1-1 Toyota-cho, Kariya-shi, Aichi Prefecture Inside Toyota Industries Corporation (58) Field surveyed (Int. Cl. ⁷ , DB name) F04B 27/08 F04B 27/14 F04B 49/00 361

Claims (1)

(57) [Claims] A swash plate for reciprocating a piston with respect to a drive shaft is provided so as to be tiltable, and a swash plate is provided in accordance with a differential pressure between a crank chamber pressure and a suction pressure. inclined angle change before Kihasu plate Te, in the swash Itashiki variable displacement compressor to control the discharge capacity, communicates the bleed passage to the crank chamber and the suction chamber, and the valve chamber in the middle of the bleed passage A valve hole is provided, and a valve body that opens and closes the valve hole is accommodated in the valve chamber located on the crank chamber side, and the valve body is constantly urged to an open position by an urging member, and the suction pressure is reduced. Pressure sensing control means for sensing and controlling the valve body in the closing direction when the suction pressure decreases is provided .
Swash plate type variable capacity compressor.