JPS63198787A - Variable-capacity piston type compressor - Google Patents

Abstract

PURPOSE:To improve the compression efficiency by providing a capacity control spool moved by a pressure chamber and an energizing member in a spool chamber on the outside of a cylinder bore. CONSTITUTION:When the pressure in a discharge chamber 17 is increased, a spool 22 is moved to the maximum capacity position by the discharge pressure and the elastic of an energizing member 25 applied to the back face S2 of the capacity control spool 22, no idle space is generated in a spool chamber 21, and the compression operation is performed. when a cooling load is decreased, gas is leaked into an intake chamber 16 from a pressure chamber 26 via a leak passage 28, and the pressure in the pressure chamber 26 is reduced. The spool 22 is moved in the direction to increase a bypass passage 23 against the elastic force of the energizing member 25, a cylinder bore 8 and a swash plate chamber 5 are communicated, and the compression capacity is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a variable displacement piston compressor such as a swash plate compressor or a swinging inclined plate compressor.

(Prior Art) As a variable capacity means for a swash plate compressor, the applicant has developed the seventh
Rotating shaft 2 formed in cylinder block 1 as shown in the figure
The refrigerant gas compressed in the cylinder bore 8 is transferred to the swash plate chamber 5 by a passage 53 opening from the shaft hole 1a to the circumferential surface of the cylinder bore 8, and a passage 54 leading from the shaft hole 1a and the shaft hole 1a to the swash plate chamber 5. A capacity control spool 56 is housed in the shaft hole la so as to be able to reciprocate in the axial direction of the rotating shaft 2, and a discharge pressure acts on the end surface of the capacity control spool 56. When the pressure control valve 29 is opened and the pressure in the pressure chamber 26 decreases, the spool 56 is moved by the biasing spring 57 to the seventh position.
It is moved to the right in the figure, the bypass passage 55 is opened, and the compressed refrigerant gas is returned from the cylinder bore 8 to the swash plate chamber 5 through the bypass passage 55, the effective compression work is reduced, and the large capacity operation is switched to the small capacity operation. proposed a device (Utility Application No. 61-56382).

Note that in this conventional example, members having the same functions as those in the embodiment of the present invention are given the same reference numerals, and a description of the structure is omitted.

(Problem to be Solved by the Invention) However, in the above-described compressor, even when the capacity control spool 56 completely closes the bypass passage 55, the passage 53
remains as an idle space, so the gas that is not discharged remains in this space and is re-expanded within the cylinder bore 8 during the suction stroke, reducing the amount of refrigerant gas sucked from the suction port 14a by that amount, so that the gas that is not discharged remains in this space and is re-expanded in the cylinder bore 8 during the suction stroke, thereby reducing the amount of refrigerant gas sucked from the suction port 14a. There was a problem that the compression efficiency of

In addition, during the suction stroke during small capacity operation when the capacity control spool 56 opens the bypass passage 55, in addition to the refrigerant gas sucked from the suction port 14a, the high temperature and low lubricating oil content is also discharged from the bypass passage 55. Since the refrigerant gas is sucked into the cylinder bore 8 from the bypass passage 55 again, the temperature rise in the cylinder bore 8 increases, reducing compression efficiency, and the lubricity in the cylinder bore 8 decreases, resulting in a decrease in seizure resistance. There was a problem.

In addition, since the refrigerant gas sucked in through the two paths of the suction port 14a and the bypass passage 55 is discharged only through the bypass passage 55, an unnecessary load is applied to the piston 9 especially during high-speed operation, and this also reduces the compression efficiency. There was a problem with the decline.

Structure of the Invention (Means for Solving Problems) In order to solve the above-mentioned problems, the present invention accommodates a piston in a cylinder bore formed in a cylinder block so as to be able to reciprocate and slide, and A housing forming a suction chamber and a discharge chamber is joined and fixed via a valve plate having an inlet and a discharge port opened, and a spool chamber opened to the circumferential surface of the cylinder bore during a compression stroke is provided in the cylinder block. provided radially outward,
A capacity control spool is disposed in the spool chamber between a maximum capacity position where the pressure receiving surface on the cylinder bore side is flush with the circumferential surface of the cylinder bore and a minimum capacity position which is spaced radially outward from this circumferential surface. A bypass passage is opened on the side of the spool chamber and is opened and closed by the capacity control spool, and a bypass passage is opened on the back side of the capacity control spool. A pressure chamber is provided in which the discharge pressure acts on the rear surface through a constriction passage, and the pressure chamber is provided with a biasing member that biases the capacity control spool to the maximum capacity position, and the pressure chamber and the blade chamber and the suction chamber are The air conditioner and the air conditioner are communicated with each other through a leak passage, and the leak passage is provided with a pressure control valve that controls the pressure in the pressure chamber according to the cooling load.

(Function) When the leak passage is closed by the pressure control valve and the pressure in the pressure chamber is maintained at the discharge pressure, the capacity control spool is moved to the maximum capacity position with the urging force of the urging means, and maximum capacity operation is performed. It will be done.

At this time, since no play space is formed in the cylinder bore due to the spool chamber, compression efficiency does not decrease. Also, when the cooling load decreases and the leak passage is opened by the pressure control valve, the pressure in the pressure chamber decreases and the pressure acting on the back surface of the capacity control spool plus the biasing force of the biasing means increases the capacity. The pressure acting on the control spool's cylinder bore side receiving surface is lower than that of the control spool, and the refrigerant gas compressed from the cylinder bore during the compression stroke by the piston is returned to the suction chamber side from the bypass passage, reducing the effective compression work and reducing the volume. Driving takes place. At this time, when the piston enters the suction stroke, the pressure inside the cylinder bore decreases, so the balance of the forces acting on the pressure receiving surface and the back surface of the capacity control spool is reversed, and the capacity control spool closes the bypass passage. High-temperature refrigerant gas discharged from the bypass passage is not drawn into the cylinder bore, and only low-temperature, fresh refrigerant gas is drawn from the suction port, thus ensuring lubricity within the cylinder bore even during high-speed operation.

(Example) Hereinafter, a first example in which the present invention is embodied in a swash plate compressor will be described based on FIGS. 1 to 4.

As shown in FIG. 2, a rotating shaft 2 is connected to a radial bearing 3 in a center shaft hole 1a of a pair of cylinder blocks 1 that are not in contact with each other.
A swash plate 6 located in a swash plate chamber 5 that communicates with the suction flange (as shown) is fitted and fixed to the rotating shaft 2, and a thrust bearing is mounted on the swash plate 6 and the inner wall surface of the swash plate chamber 5. 7 is interposed. A plurality of cylinder bores 8 (in this embodiment, five as shown in FIG. 3) are formed in the cylinder block 1 so as to be located at equal intervals around the shaft hole 1a and on the same circumference, A piston 9 is fitted into each cylinder bore 8 so as to be slidable back and forth in the same direction as the axis of the rotating shaft 2, and is anchored to the swash plate 6 by shoes 10 and balls 11. The swash plate 6 is connected to the swash plate chamber 5.
When the piston 9 is rotated within the rotary shaft 2, the piston 9 is reciprocated in the longitudinal direction of the rotating shaft 2.

Each cylinder bore 8 is provided on the front end surface of the cylinder block 1.
A front housing 13 is connected to the front housing 13 via a front valve plate 12 which has an inlet 12a and an outlet 12b open respectively, and an inlet 14a and an outlet 14 are also connected to the rear end surface.
A rear housing 15 is connected to the rear housing 15 via a valve plate 14 having an opening at b, and these are integrally tightened and fixed together with the cylinder block 1 by bolts 4. At the outer periphery of the front and rear housings 13.15, there is a suction chamber 16 which communicates with the swash plate chamber 5 through a suction passage 1b which also serves as an insertion hole for the port 4 penetrated through the cylinder block 1, and at the center thereof. A discharge chamber 17 that communicates with a discharge flange (as shown) is formed by a discharge passage (as shown) formed in the cylinder block 1, respectively. moreover,
A suction valve mechanism 18 and a discharge valve mechanism 19 are provided at positions corresponding to the suction ports 12a, 14a and the discharge ports 12b, 14b of the front and rear valve plates 12.14. Then, due to the reciprocating movement of the piston 9, the suction port 12a is removed from the suction chamber 16.

sucking refrigerant gas into the cylinder bore 8 through 14a;
The refrigerant gas compressed in the cylinder bore 8 is discharged from the discharge port 12b.
, 14b to the discharge chamber 17.

A stepped portion 1c is formed in the shaft hole 1a of the cylinder block 1 of the pre-filler example, and a disc-shaped partition plate 2 is formed in the stepped portion 1c.
0 is inserted and fixed. The cylinder block 1 has a spool chamber 21 that opens on the circumferential surface of each cylinder bore 8 during the compression stroke and that is oriented toward the center of the shaft hole 1a.
A capacity control spool 22 is accommodated in the spool chamber 21 so as to be slidable back and forth in the radial direction of the cylinder bore 8. Further, a plurality of M bypass passages 23 are formed in the cylinder block 1, one end of which opens into the side surface of the spool chamber 21, and the other end of which opens into the swash plate chamber 5 serving as the low pressure chamber.

At the boundary between the spool chamber 21 and the bypass passage 23 of the cylinder block 1, a locking convex portion 22a integrally formed on the side surface of the capacity control spool 22 is locked.
A locking convex portion 24 is integrally formed to restrict the pressure receiving surface S1 on the cylinder bore 8 side to a position where it is flush with the inner circumferential surface of the cylinder bore 8, that is, a maximum capacity position. Furthermore, a locking step portion 20a for locking the locking convex portion 22a is formed in the partition plate 20 in correspondence with the locking convex portion 24, and the cylinder bore 8 and the bypass passage 23 are connected to each other. a position where the bypass passage 23 is in communication and has a maximum opening degree;
In other words, the minimum capacity position of the capacity control spool 22 is regulated.

A locking pin 20b is integrally formed in the center portion of the rear side of the partition plate 20, and a plurality of pressing arms 25a are radially attached to the pin 20b for normally urging the capacity control spool 22 to the maximum capacity position. A biasing member 25 made of a plate spring integrally formed with is engaged.

The space accommodating the biasing member 25 and the space 15a formed in the center of the rear housing 15 communicate with each other through a through hole 14C formed in the rear valve plate 14, and are connected to the back surface S2 of the capacity control spool 22. One pressure chamber 26 is formed to apply a pressure equivalent to the discharge pressure. The pressure chamber 26 communicates with the pressure chamber 26 through a throttle passage 27 provided through the partition wall 15b of the rear housing 15 that partitions the discharge chamber 17 therefrom, so that refrigerant gas corresponding to the discharge pressure is supplied to the pressure chamber 26.

On the other hand, a leak passage 28 is formed in the rear housing 15 to communicate the pressure chamber 26 and the suction chamber 16, and in the middle of the leak passage 28, the leak passage 28 is opened and closed according to the cooling load. A pressure control valve 29 is installed to adjust the pressure acting on the back surface S2 of the capacity control spool 22 by controlling the amount of gas leaking from the pump to the suction chamber 16, that is, the pressure in the pressure chamber 26. To explain the pressure control valve 29, a valve seat 30 is formed in the middle of the leak passage 28, and a ball valve 32 biased in the closing direction by a biasing spring 31 is accommodated in the valve seat 30. Further, a pressure sensitive chamber 33 that opens at the rear end surface of the rear housing 15 is formed near the downstream of the valve seat 30, and the pressure sensitive chamber 33 is connected to the mounting plate 3.
4, a pressure regulator 36 is attached to the mounting plate 34 via a bellows 35, and the atmospheric chamber 3 between the mounting plate 34 and the pressure regulator 36 is sealed.
A coil spring 38 is interposed on the 7 side for biasing the pressure regulator 36 in the direction of opening the ball valve 32. When the cooling load decreases and the pressure in the suction chamber 16, that is, the pressure in the pressure sensitive chamber 33, decreases, the pressure regulator 36 is moved toward the ball valve 32 by the coil spring 38, opening the ball valve 32. Refrigerant gas leaks from the chamber 26 via the leak passage 28, and this pressure drop in the pressure chamber 26 causes the capacity control spool 22 to move in the direction of increasing the opening of the bypass passage 823 against the elasticity of the biasing member 25. I'm trying to make it happen. On the other hand, when the pressure in the suction chamber 16 increases due to the increased cooling load and the pressure in the pressure sensitive chamber 33 increases, the pressure regulator 36 is moved away from the ball valve 32 and the leak passage 28 is closed. , the pressure in the pressure chamber 26 is increased, and the capacity control spool 22 is moved in the direction of closing the bypass passage 23 together with the elasticity of the biasing member 25.

The rear capacity control mechanism configured as described above is also provided on the front side with a similar configuration. This front side capacity control mechanism uses an annular partition plate 20 because the rotation shaft 2 passes through the partition plate 20, and also between the partition plate 20 and the rotation shaft 2 and between the front housing 13 and the rotation shaft 2. Seal members 39 and 40 are provided on each side to define a small-volume pressure chamber 26, but the other configurations are almost the same as the rear-side capacity control mechanism, so the same reference numerals and explanations will be given. Omitted.

Next, the operation of the swash plate compressor constructed as described above will be explained.

When the compressor is stopped, the pressures in the suction chamber 16, discharge chamber 17, pressure chamber 26, pressure sensitive chamber 33, etc. are maintained at substantially the same pressure, which is higher than the pressure in the atmospheric chamber 37. In this state, the capacity control spool 22 is pressed to the maximum capacity position by the pressing arm 25a of the biasing member 25, the bypass passage 23 is closed, and the pressure regulator 36 is pushed against the elasticity of the coil spring 38 by the pressure of the pressure sensitive chamber 33. is spaced apart from the ball valve 32 so that the ball valve 32
The valve seat 30 is closed and the leak passage 28 is closed.

Now, when the swash plate 3 is rotated by the rotary shaft 2 and the piston 9 is reciprocated within the cylinder bore 8 to start compression operation, the refrigerant gas in the swash plate chamber 5 passes through the suction passage 1b to the suction chamber 1.
6 and is sucked into the cylinder bore 8 from the suction chamber 16 through the suction ports 12a and 14a, where it is compressed and then discharged to the discharge port 12b.

It is discharged from the discharge chamber 17 from the discharge chamber 14b, and is further pressure-fed from a discharge passage (not shown) to the discharge flange.

At this early stage of startup. Although the compression operation within the cylinder bore 8 is performed normally, the pressure within the pressure chamber 26 has not yet reached the discharge pressure during normal operation, so the capacity control spool 22 is compressed every time the piston 9 is compressed. The liquid is pushed back toward the pressure chamber 26 against the elasticity of the biasing member 25, and is therefore essentially in a small capacity operation state, reducing the starting torque at the initial stage of compression and preventing liquid compression. can.

When the compression operation continues and the pressure in the discharge chamber 17 becomes sufficiently large, the pressure in the pressure chamber 26 also becomes high.
Due to the resultant force of the discharge pressure acting on the back surface S2 of the capacity control spool 22 and the elasticity of the biasing member 25, the spool 22 remains biased and held at the maximum capacity position, and full capacity operation is performed. During this maximum capacity operation, the pressure receiving surface S1 of the capacity control spool 22 is flush with the inner peripheral surface of the cylinder bore 8 as shown in FIG.
No idle space is created in the compressor, and therefore the compression operation is performed efficiently.

As this maximum capacity operation continues and the temperature inside the vehicle decreases and the cooling load decreases, the suction pressure decreases, and when this pressure decreases below the set value, the pressure regulator 36 is turned off by the coil spring 38. valve 32
Since the ball valve 32 is moved to the side, the ball valve 32 is opened. Then, the suction chamber 16 is leaked from the pressure chamber 26 through the leak passage 28.
Since the gas leaks to the inside of the pressure chamber 26, the pressure inside the pressure chamber 26 decreases. As a result, the capacity control spool 22 is moved in the direction of increasing the bypass passage 23 against the elasticity of the biasing member 25, and the cylinder bore 8 and the swash plate chamber 5 are communicated with each other as shown in FIG. Since the effective compression work of the air conditioner is reduced, the compression capacity is reduced, resulting in a small capacity operating state for small cooling loads.

In this small capacity operation state, when the piston 9 enters the suction stroke from the compression stroke, the balance of forces acting on the pressure receiving surface S1 and the back surface S2 of the displacement control spool 22 is reversed and the bypass passage 23 is closed. Since fresh refrigerant gas with a low temperature is sucked only by , 14a, the lubricity within the cylinder bore 8 is improved, the seizure resistance during high-speed operation is increased, and the load acting on the piston 9 is reduced to improve compression efficiency. can be improved.

Next, a second embodiment of the present invention will be described with reference to FIG. In this second embodiment and a third embodiment to be described later, members having the same functions as those in the first embodiment are given the same reference numerals and explanations thereof will be omitted.

This second embodiment communicates the front and rear pressure chambers 26, 26 with each other outside the compressor, and the suction passage I
A solenoid valve 42 as a pressure control valve is provided for the leak pipe 41 that leaks gas to the air conditioner I), and the solenoid valve 42 is connected to a control circuit 43 that changes the duty ratio according to the cooling load. Note that 43a is a temperature sensor connected to the control circuit 43, and is capable of detecting the temperature inside the vehicle interior or the temperature at the outlet of the evaporator.

In this second embodiment, when the cooling load becomes small, the duty ratio is increased to increase the amount of gas leaked from the solenoid valve 42, thereby lowering the pressure in the pressure chamber 26 and reducing the capacity. When the load increases, the duty ratio is lowered to reduce the amount of leakage, and the pressure in the pressure chamber 26 is slightly increased to increase the capacity. Therefore, in this second embodiment, more accurate capacity control is possible than in the first embodiment, but other effects are the same as in the first embodiment.

Next, a third embodiment of the present invention will be described with reference to FIG.

In this third embodiment, the pressure control valve 29 is integrated into the suction flange 52 so that it also serves as a suction throttle valve. That is, the spool valve 4 is
A coil spring 46 is interposed in the mounting cylinder 45 to always bias the spool valve 44 in the direction of reducing the suction amount, and the spool valve 44 and the suction flange 52 A pressure sensitive chamber 4 is installed inside the bellows 47 provided in the
8 and a communication path 4 provided in the spool valve 44.
9 communicates the suction passage 52a in the suction flange 52 with the pressure sensitive chamber 48, forming an atmospheric chamber 50 outside the bellows 47.

Further, the pressure chamber 2 is provided in the suction flange 52, the cylinder block 1, and the front and rear housings 13.15.
A leak passage 51 is formed which communicates with the communication passage 49, and its open end on the suction flange 52 side can be selectively communicated or closed with the communication passage 49 depending on the position of the spool valve 44.

Therefore, in this third embodiment, when the cooling load decreases and the suction pressure decreases, the spool valve 44 is moved to the right in FIG. When the spool valve 44 is moved to this position, the suction passage 52a and the leak passage 51 are communicated with each other via the communication passage 49, and as a result, the pressure in the pressure chamber 26 decreases, and the capacity further decreases. On the other hand, when the cooling load increases, the pressure in the suction passage 52a increases, so the spool valve 44 is moved to the right in FIG.
1 is cut off, and as a result, the pressure within the pressure chamber 26 increases and the capacity increases.

In this third embodiment, the capacity is reduced by the suction throttling spool valve 44, and the capacity is further reduced by the capacity control spool 22, so that the capacity control range is different from that of the above-mentioned first and second embodiments. However, other functions and effects are the same as in the first embodiment.

Note that the present invention can also be embodied as follows.

(1) In the embodiment described above, each cylinder bore 8 is provided with a spool 22, but this number may be reduced by half or provided only on the rear side.

(2) In the embodiment described above, the biasing member 25 was formed integrally, but it can be divided.

(3) In the above embodiment, the discharge chamber 17 and the pressure chamber 26 are communicated with each other by the throttle passage 27, but instead of this, a valve means (the illustrated passage) is used.
shall be established.

(4) In addition to the swash plate type compressor, a so-called wobble type piston type compressor of a swinging inclined plate type is used.

Effects of the Invention As detailed above, in the present invention, no idle space is formed in the cylinder pore in the maximum capacity operating state, so compression efficiency is increased. Additionally, when the cooling load is reduced and the piston enters the suction stroke, the balance of forces acting on the pressure receiving surface and back surface on the cylinder bore side of the capacity control spool is reversed, causing the capacity control spool to move into the bypass passage. Since the refrigerant gas once discharged from the bypass passage is not sucked into the cylinder pore, only the low-temperature refrigerant gas from the suction port is sucked in. Therefore, even during high-speed operation, the lubrication inside the cylinder pore is maintained. This has the effect of not only being able to maintain its properties but also reducing the load acting on the piston and improving compression efficiency.

[Brief explanation of the drawing]

FIG. 1 is an enlarged exploded perspective view of the main parts showing a first embodiment of the present invention as a swash plate compressor, and FIG. 2 is a vertical cross-sectional view of the central part showing the minimum capacity state of the swash plate compressor. FIG. 3 is a sectional view taken along the line A-A in FIG. 2, FIG. 4 is a partially enlarged sectional view showing the swash plate compressor in its maximum capacity state, and FIGS. 5 and 6 are respectively a second embodiment of the present invention. FIG. 7 is a longitudinal cross-sectional view of the central part showing the third embodiment, and FIG. 7 is a cross-sectional view of the conventional example.

Claims (2)

[Claims] 1. A piston is housed in a cylinder bore formed in a cylinder block so as to be able to slide back and forth, and a housing forming a suction chamber and a discharge chamber is connected to the end face of the cylinder block via a valve plate with an inlet and a discharge port opened. The cylinder block is provided with a spool chamber radially outward of the cylinder bore that opens on the circumferential surface of the cylinder bore during the compression stroke, and the spool chamber has a capacity control spool with a pressure receiving surface on the cylinder bore side. The spool chamber is accommodated so as to be slidable back and forth between a maximum capacity position that is flush with the circumferential surface of the cylinder bore and a minimum capacity position that is spaced radially outward from the circumferential surface, and a suction chamber is provided on the side surface of the spool chamber. A bypass passage that communicates with the side and is opened and closed by the capacity control spool is opened, and a pressure chamber is provided on the back side of the capacity control spool that throttles the discharge pressure on the discharge chamber side and acts on the back side through the passage. The pressure chamber is provided with a biasing member that biases the capacity control spool to the maximum capacity position, and the pressure chamber and the suction chamber side are communicated through a leak passage, and the leak passage has a biasing member that biases the capacity control spool to the maximum capacity position. A variable displacement piston type compressor provided with a pressure control valve that controls the pressure in the pressure chamber. 2. The cylinder block is formed with a plurality of cylinder bores located at equal intervals and on the same circumference, and the end face of the cylinder block has a spool chamber cut out for each cylinder bore and toward the center of the circle. A biasing member made of a plate spring having a plurality of pressing arms integrally formed in a radial manner within the pressure chamber is held by a locking pin protruding from a predetermined position within the pressure chamber, and each of the pressing arms controls the displacement. The variable displacement piston compressor according to claim 1, wherein the back surfaces of the spools are each pressed.