JPH09144653A - Double-end piston type compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the manufacturing cost with a simple structure, and relieve the sudden build-up of a compression load in the connection of a clutch and the compression of a liquid coolant. SOLUTION: Both front and rear discharge chambers 30, 31 are allowed to communicate each other by a communicating passage 32. A cylinder block 11 and a rear housing 14 support a spool 38 in such a manner as to be movable. A movable discharge valve 44 is fixed to the spool 38 in such a manner that the discharge valve can contact and separate from a rear discharge port 43. The spool 38 is energized by a spring 48 to arrange the movable discharge valve 44 in a non-working position separated from the discharge port 43. The discharge pressure of the rear discharge chamber 31 acts on the back surface of the spool 38 through a pressure inlet passage 49 within the rear housing 13, whereby the spool 38 is moved against the spring 48 to arrange the movable discharge valve in a working position connected to the discharge port 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-headed piston compressor used in, for example, a vehicle air conditioner.

[0002]

2. Description of the Related Art Generally, in a fixed displacement double-headed piston type compressor, a front housing and a rear housing are joined and fixed to both ends of a cylinder block through valve plates. A plurality of cylinder bores for accommodating a double-headed piston are formed in the cylinder block, and a suction chamber and a discharge chamber are defined in the front housing and the rear housing, respectively. Then, due to the reciprocating movement of the piston, the refrigerant gas is sucked from the suction chamber into the cylinder bore, compressed, and then discharged into the discharge chamber.

By the way, in this double-headed piston type compressor, a plurality of discharge holes are formed in both valve plates in correspondence with the cylinder bores, and a fixed discharge valve is arranged so as to open and close these discharge holes. There is. These discharge valves are closed when the refrigerant gas is sucked in and compressed, and are opened only when the refrigerant gas is discharged.

In such a compressor, when the clutch is operatively connected to an external drive source such as a vehicle engine and the piston starts reciprocating, the compression load of the compressor rises rapidly. Particularly in a vehicle-mounted form, this sudden change in the compression load may be transmitted to the external drive source such as the vehicle engine as a change in the load torque to excite the change in the rotational speed of the vehicle engine or the like. This fluctuation in the number of revolutions is called a start shock and causes a bad feeling in the body.

When the compressor is started, a compressive force may be applied to the liquid refrigerant accumulated in the cylinder bore.
When the compressor is in this so-called liquid compression state, there is a problem that a large compression load acts on the piston and vibration and noise are generated.

On the other hand, conventionally, a variable capacity compressor has been proposed. For example, in the variable displacement double-headed piston compressor described in Japanese Utility Model Laid-Open No. 59-116586, a movable discharge valve is arranged corresponding to the discharge hole of the rear valve plate. Further, the movable discharge valve is driven by the valve drive device including the spool so that the movable discharge valve is brought into close contact with the valve plate in a corresponding state with the discharge hole and the inactive position separated from the valve plate and retracted from the corresponding state with the discharge hole. It is designed to be switched between and. Control pressure is supplied to the back surface of the spool in the valve drive device through an external supply passage of the compressor. Then, the movable discharge valve is switched between the operating position and the non-operating position according to the control force, the bypass amount of the refrigerant gas flowing into the discharge chamber from the cylinder bore through the discharge hole is adjusted, and the discharge capacity is changed. .

In this type of variable displacement double-headed piston compressor, the movable discharge valve is switched to the inoperative position by the valve drive device, and the operation is started from the minimum discharge capacity state. Therefore, when the clutch is connected and the liquid refrigerant is compressed, a large compression load does not act on the piston, and there is no possibility of generating vibration or noise.

[0008]

However, the above publication does not disclose the mechanism for supplying the control pressure to the valve drive device in detail. However, as such a control pressure supply mechanism, it is conceivable that an electromagnetic opening / closing valve is provided in the middle of the external supply path and a control computer for controlling the electromagnetic opening / closing valve is provided. In this configuration, the control computer outputs an excitation / demagnetization command to the solenoid of the electromagnetic opening / closing valve based on the detected information such as the cooling load of the external refrigerant circuit to open / close the external supply path.
As a result, the supply of a predetermined pressure to the back surface of the spool is controlled, and the movable discharge valve is arranged to be switched between the working position and the non-working position. Here, at the minimum discharge capacity operation,
When the high-pressure refrigerant gas compressed in the front cylinder bore flows into the rear discharge chamber, the pressure in the rear discharge chamber is increased. Then, the high discharge pressure may act on the back surface of the movable discharge valve, and the movable discharge valve may be moved from the inoperative position to the operating position against the control of the discharge capacity. In order to avoid such a problem, a check valve is arranged in the middle of the discharge passage.

Therefore, in such a conventional variable displacement compressor, a supply passage is connected to the back side of the spool in the valve drive device from the outside of the compressor, and an electromagnetic opening / closing valve is arranged in the external supply passage. At the same time, it is necessary to equip a control computer to control the opening and closing of the solenoid valve. In addition, it is necessary to dispose a check valve in the middle of the discharge passage. Therefore, this variable capacity compressor has a problem that the structure is complicated and the manufacturing cost is increased.

An object of the present invention is that the structure is simple and can be manufactured at low cost, and the compression load acting on the piston can be alleviated when the clutch is engaged and the liquid refrigerant is compressed, so that vibration and noise can be reduced. An object of the present invention is to provide a double-headed piston type compressor that can suppress the occurrence of

[0011]

In order to achieve the above object, in the invention according to claim 1, a front housing and a rear housing are joined and fixed to both ends of a cylinder block through valve plates, and the cylinder block is attached to the cylinder block. Forms a plurality of cylinder bores for accommodating a double-headed piston, and forms a suction chamber and a discharge chamber in the front housing and the rear housing, respectively, and reciprocates the pistons to move the refrigerant gas from the suction chamber into the cylinder bore. In a double-headed piston type compressor, which sucks and compresses and then discharges into the discharge chamber through a discharge hole formed in the valve plate, a communication passage that connects the front discharge chamber and the rear discharge chamber A spool movably supported in the discharge chamber of the rear housing, and at least the rear valve plate. The spool is moved in one direction so that the movable discharge valve, which is provided so as to be able to move toward and away from one of the discharge holes and is movable in synchronization with the spool, and the movable discharge valve are arranged in an inoperative position, which is separated from the discharge holes. A biasing means for biasing,
In the rear housing, there is provided a pressure introducing passage that communicates the discharge chamber with the back surface of the spool.

According to a second aspect of the present invention, in the double-headed piston type compressor according to the first aspect, a seal ring for sealing between a suction pressure region and a discharge pressure region is provided on the outer periphery of the spool. It is arranged.

According to a third aspect of the present invention, in the double-headed piston type compressor according to the first or second aspect, the dead volume of the rear cylinder bore in which communication with the discharge chamber is opened and closed by the movable discharge valve is The dead volume is set to be smaller than the dead volume of the front cylinder bore that faces the cylinder bore via the piston.

In the invention described in claim 4, claims 1 to 3 are provided.
In the double-headed piston compressor according to any one of items 1 to 3, the pressure introducing passage is a hole or a groove formed in the rear housing.

According to the fifth aspect of the present invention, the first to fourth aspects are provided.
In the double-headed piston type compressor according to any one of items 1 to 3, a recess is formed on the back surface of the spool. According to a sixth aspect of the invention, in the double-headed piston compressor according to any of the third to fifth aspects, the dead volume of the cylinder bore on the front side forms a recess on the front end face of the piston. It is set by.

In the invention according to claim 7, claims 1 to 6
In the double-headed piston compressor according to any one of items 1 to 4, a throttle portion is provided in the pressure introduction passage. Therefore,
When the double-headed piston compressor according to claim 1 is stopped,
The movable discharge valve is arranged at an inoperative position separated from the discharge hole by the urging force of the urging means. In this state, the clutch is operatively connected to the external drive source by connecting the clutch,
When the piston starts to reciprocate, the refrigerant gas is sucked, compressed, and discharged in the compression chamber in the front cylinder bore as the piston reciprocates. On the other hand, the refrigerant gas sucked into the rear-side compression chamber is discharged into the discharge chamber with almost no compression because the movable discharge valve is arranged at the inoperative position.

Here, the front side discharge chamber and the rear side discharge chamber communicate with each other through the communication passage, and a part of the discharge pressure of the front side discharge chamber is introduced into the rear side discharge chamber through this communication passage. When the discharge pressure acting on the back surface of the spool exceeds a predetermined value, the spool is moved against the biasing force of the biasing means, and the movable discharge valve is joined to the discharge hole and is placed at the working position. In this state, also in the rear side compression chamber, due to the reciprocating motion of the piston, the refrigerant gas is sucked from the suction chamber into the cylinder bore and compressed, and then the normal compression operation is performed in which the refrigerant gas is discharged into the corresponding discharge chamber. .

That is, in the compression chamber in the rear cylinder bore, the refrigerant gas in the compression is discharged into the discharge chamber with almost no resistance from the time the clutch is engaged until the movable discharge valve is placed in the operating position. . Further, the front side discharge chamber and the rear side discharge chamber are communicated with each other through the communication passage, and a part of the discharge pressure of the front side discharge chamber is introduced into the rear side discharge chamber through this communication passage. Therefore, after a lapse of a predetermined time from the start of operation of the compressor, the discharge pressure of the rear discharge chamber is surely increased and this discharge pressure is guided to the back surface of the spool. Then, at the start of the compression operation, the rapid rise of the compression load acting on the piston, that is, the starting shock can be alleviated, and the generation of vibration and noise can be suppressed.

Further, an external supply path for supplying a control pressure to the compressor is connected, an electromagnetic opening / closing valve is arranged in the external supply path, and a control computer for controlling the electromagnetic opening / closing valve is provided. It is not necessary to arrange a check valve in the discharge passage. Therefore, the structure of the compressor can be simplified and the compressor can be manufactured at low cost.

Also, when the compressor is started, even if the liquid refrigerant is accumulated in the cylinder bore, the liquid refrigerant in the rear cylinder bore is discharged into the discharge chamber with almost no resistance, as in the case of connecting the clutch. It Therefore, the inside of the cylinder bore on the rear side is hardly in a so-called liquid compression state, and it is possible to suppress the generation of vibration and noise.

In the compressor of the second aspect, when the spool is moved, the seal ring imparts movement resistance to the spool. Therefore, the moving speed of the movable discharge valve from the non-acting position to the working position can be reduced. Then, the rise of the compression load acting on the piston can be alleviated more effectively.

In the compressor according to the third aspect of the present invention, the dead volume of the compression chamber in the front side cylinder bore, which is opposed to the rear side cylinder bore in which the movable discharge valve is arranged, for one piston is the rear volume. It is set to be larger than the dead volume of the compression chamber in the side cylinder bore. That is, the front-side compression chamber has a larger volume than the rear-side compression chamber when the piston reaches the top dead center. Therefore, in the front-side compression chamber, the maximum pressure in the vicinity of the top dead center of the piston is reduced and overcompression is reduced. Then, the compression load generated in the compression chamber in the front side cylinder bore is alleviated, and the generation of vibration and noise can be suppressed more effectively.

In the compressor according to the fourth aspect, the pressure introducing passage for guiding the discharge pressure from the discharge chamber to the back surface of the spool can be simply constructed by forming the hole or groove in the rear housing. it can.

In the compressor according to the fifth aspect, the discharge pressure introduced from the pressure introducing passage acts on the recess on the back surface of the spool. Therefore, it is possible to reliably receive the discharge pressure on the back surface of the spool, and it is possible to prevent the sudden movement of the spool by the damper action of the gas pressure in the recess.

In the compressor according to the sixth aspect, the dead volume can be easily set by forming a recess on the front end face of the piston.
In the compressor according to the seventh aspect, when the discharge pressure is introduced from the discharge chamber to the back surface of the spool through the pressure introduction passage, the flow of the discharge pressure is suppressed by the throttle portion. Therefore, the moving speed of the movable discharge valve from the non-acting position to the working position can be reduced, and the rise of the compression load acting on the piston can be more effectively mitigated.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) A first embodiment of the present invention will be described in detail below with reference to FIGS.

As shown in FIG. 1, the pair of cylinder blocks 11 constituting the main housing are joined to each other at their opposite end edges. The front housing 12
It is joined to the front end surface of the cylinder block 11 via a front valve plate 13. Rear housing 14
Are joined to the rear end surface of the cylinder block 11 via the rear valve plate 15.

A plurality of through bolts 16 are screwed into the screw holes 17 of the rear housing 14 from the front housing 12 through both cylinder blocks 11 and both valve plates 13 and 15. The front housing 12 and the rear housing 14 are fastened and fixed to both end surfaces of the cylinder block 11 by these through bolts 16.

The drive shaft 18 is rotatably supported at the center of the cylinder block 11 and the front housing 12 through a pair of radial bearings 19, and a lip seal 20 is provided between the outer periphery of the front end and the front housing 12. Is installed. The drive shaft 18 is operatively connected to an external drive source such as a vehicle engine via a clutch (not shown), and the drive force of the external drive source is transmitted when the clutch is connected to be rotationally driven.

A plurality of cylinder bores 21 are provided in each cylinder block 1 so as to extend in parallel with the drive shaft 18.
1 are formed so as to penetrate between the two end portions on the same circumference at predetermined intervals. Double-headed piston 22 is used for each cylinder bore 2
1, the compression chambers 23a and 23b are formed in the cylinder bores 21 between the valve plates 13 and 15 and the two end surfaces thereof.

The crank chamber 24 is defined inside the middle of both cylinder blocks 11. The swash plate 25
The drive shaft 18 is fitted and fixed in the crank chamber 24, and the outer peripheral portion thereof is anchored to the intermediate portion of the piston 22 via a pair of hemispherical shoes 26. Then, when the drive shaft 18 is rotated, the piston 22 is reciprocated via the swash plate 25. A pair of thrust bearings 27 are provided on both end surfaces of the swash plate 25 and each cylinder block 11
Between the inner end face of the thrust bearing 2
A swash plate 25 is sandwiched and held between the cylinder blocks 11 via the shaft 7. The crank chamber 24 is connected to an external refrigerant circuit via a suction port (not shown) and constitutes a suction pressure region.

Front suction chamber 28 and rear suction chamber 2
The reference numeral 9 is formed in an annular shape on the outer peripheral portions of the front housing 12 and the rear housing 14, and is connected to the crank chamber 24 via an intake passage 11a formed in the cylinder block 11 and both valve plates 13 and 14. . The front-side discharge chamber 30 and the rear-side discharge chamber 31, which form the discharge pressure region, are formed in an annular shape on the inner peripheral portions of the front housing 12 and the rear housing 14, and are connected to an external refrigerant circuit via a discharge port (not shown). Has been done. The communication passage 32 is formed so as to penetrate between both ends of the cylinder block 11, and the front-side discharge chamber 30 is provided through the communication passage 32.
And the rear discharge chamber 31 communicate with each other.

The front side intake valve mechanism 33 and the rear side intake valve mechanism 34 are formed in the valve plates 13 and 15 and have a plurality of intake holes corresponding to the cylinder bores 21, respectively.
And a suction valve for opening and closing those suction holes. Then, with the movement of the piston 22 from the top dead center position to the bottom dead center position, the suction valve mechanisms 33 and 34 are used to move the suction chambers 28 and 29 from the compression chambers 23 of the cylinder bores 21.
Refrigerant gas is drawn into a and 23b.

The front side discharge valve mechanism 35 includes a plurality of discharge holes formed in the front side valve plate 13 and corresponding to each cylinder bore 21, and a fixed type discharge valve for opening and closing the discharge holes. Then, with the movement of the piston 22 from the bottom dead center position to the top dead center position, the discharge valve mechanism 35 compresses the refrigerant gas in the front side compression chamber 23a of each cylinder bore 21 to a predetermined pressure, and It is discharged to the side discharge chamber 30.

As shown in FIGS. 1 and 2, the accommodating chamber 36, which has a circular cross section, is connected to the rear radial bearing 19 of the drive shaft 18 so as to communicate with the cylinder block 1.
1 and the rear valve plate 15. The cylinder chamber 37 is formed on the inner surface of the rear housing 14 inside the rear discharge chamber 31 so as to be arranged on the same axis as the accommodation chamber 36.

The spool 38 is movably accommodated in the accommodation chamber 36 and the cylinder chamber 37, and is divided into a first member 38a located in the accommodation chamber 36 and a second member 38b located in the cylinder chamber 37. Has been done. And this first
The member 38a and the second member 38b are fastened and fixed by a bolt 39 and a nut 40 extending in the axial direction in a state of being joined to each other.

The first member 38a is formed in a cylindrical shape with its rear end face closed, and a recess 41 is formed in the front surface thereof, and the recess 41 receives the suction pressure of the crank chamber 24 as the suction pressure region. The second member 38b is formed in a cylindrical shape with its front end face closed, and a recess 42 is formed on the back surface thereof, and the recess 42 receives the discharge pressure of the rear discharge chamber 31 as a discharge pressure region.

A plurality of rear side discharge holes 43 are formed in the rear side valve plate 15 corresponding to the cylinder bores 21. The movable discharge valve 44, together with the retainer 45, is sandwiched and fixed between both members 38a and 38b of the spool 38, and an opening / closing portion 44a corresponding to each rear side discharge hole 43 is formed on the outer periphery thereof so as to be capable of coming into contact with and separating from each rear side discharge hole 43. Guide pin 46
The rear housing 14 and the rear valve plate 1 so as to penetrate through the movable discharge valve 44 and a part of the retainer 45.
It is arranged between 5 and 5. And this guide pin 4
By 6, the rotation of the movable discharge valve 44 is restricted, and only the movement in the axial direction is allowed.

The spring seat 47 is joined to the rear end of the rear radial bearing 19, and a spring 48 as an urging means is interposed between the spring seat 47 and the first member 38a of the spool 38. Has been done. Then, as shown in FIG. 1, the biasing force of the spring 48 urges the spool 38 to move rearward so that the movable discharge valve 44 moves to the rear discharge hole 43.
Is placed in a non-acting position apart from. The inoperative position is positioned by contact between the back surface of the retainer 45 and the protrusion 14a of the rear housing 14. The gap 14 is formed between the rear end surface of the second member 38b and the inner wall surface of the rear housing 14 facing the rear end surface.
b is secured.

A pressure introducing passage 49 consisting of a plurality of holes is formed in the rear housing 14 so as to connect the rear discharge chamber 31 and the rear end of the cylinder chamber 37. The discharge pressure of the rear discharge chamber 31 passes through the pressure introducing passage 49 and the gap 14b, and the second member 38b of the spool 38 is discharged.
Is guided into the back recess 42 of the. Then, as shown in FIG. 3, when the discharge pressure in the rear concave portion 42 of the second member 38b rises above a predetermined value, the spool 38 is moved forward against the urging force of the spring 48 or the like and is movable. The discharge valve 44 is arranged at an operating position where it is joined to the rear discharge hole 43.

As shown in FIG. 1, the throttle portion 50 is formed in the pressure introducing passage 49. The throttle portion 50 allows the second member of the spool 38 to pass from the rear discharge chamber 31 through the pressure introducing passage 49. The flow of the discharge pressure introduced into the rear concave portion 42 of 38b is suppressed. This reduces the moving speed of the movable discharge valve 44 when the movable discharge valve 44 is moved from the non-acting position to the working position.

The seal ring 51 is attached to the outer periphery of the first member 38a of the spool 38. The outer peripheral surface of the seal ring 51 and the inner peripheral surface of the accommodation chamber 36 and the first
By closely contacting the outer peripheral surface of the member 38a, the crank chamber 24 serving as the suction pressure region and the rear discharge chamber 31 serving as the discharge pressure region are sealed. Then, when the spool 38 is moved between the working position and the non-working position,
The seal ring 51 is brought into sliding contact with the inner peripheral surface of the accommodation chamber 36 to impart movement resistance to the spool 38, and the movement speed of the spool 38 is reduced.

The recess 52 for setting the dead volume is
It is formed on the front end surface of each piston 22. Due to the formation of the recess 52, the dead volume of the front compression chamber 23a becomes larger than the dead volume of the rear compression chamber 23b when the pistons 22 reciprocate. The dead volume is the top dead center position of the piston 22,
Valve plates 13, 1 facing the end surface of the piston 22
The volume of the compression chambers 23a and 23b formed between the compression chambers 5 and 5.

Next, the operation of the double-headed piston type compressor constructed as described above will be described. Now, when the compressor is stopped, as shown in FIG. 1, the spool 38 is moved backward by the urging force of the spring 48, and the movable discharge valve 44 is moved.
Is arranged at an inactive position separated from the rear discharge hole 43. In this state, when the driving force is transmitted from the external drive source such as the vehicle engine to the drive shaft 18 by the engagement of the clutch, the piston 22 is linked with the rotation of the swash plate 25.
Is reciprocated.

First, in the compression chamber 23a in the cylinder bore 21 on the front side, the reciprocating movement of the piston 22 causes the suction of the refrigerant gas from the suction chamber 28, the compression in the compression chamber 23a, and the discharge chamber 30. The discharge cycle (normal compression operation) is started. On the other hand, the refrigerant gas sucked into the compression chamber 23b from the suction chamber 29 on the rear side with the reciprocating motion of the piston 22 is hardly compressed because the movable discharge valve 44 is arranged in the inoperative position. Discharge chamber 31
It is discharged into. Here, the front side discharge chamber 30 and the rear side discharge chamber 31 are communicated with each other via a communication passage 32,
The discharge pressure in both discharge chambers 30 and 31 is introduced into the back surface recess 42 of the second member 38b of the spool 38 through the pressure introducing passage 49 and the gap 14b.

When the discharge pressure acting on the back surface of the spool 38 rises above a predetermined value, the spool 38 is moved forward against the urging force of the spring 48, etc., as shown in FIG. The valve 44 is arranged in the working position where it is joined to the discharge hole 43. And the rear cylinder bore 21
Also in the compression chamber 23b, due to the reciprocating movement of the piston 22, a normal compression operation is started in which the refrigerant gas is sucked from the suction chamber 29 and compressed and then discharged into the corresponding discharge chamber 31.

On the other hand, when the clutch is disengaged, the transmission of the driving force from the external drive source such as the vehicle engine to the drive shaft 18 is stopped. Then, when the piston 22 stops reciprocating and the compressed refrigerant gas is no longer discharged to the rear discharge chamber 31, the discharge pressure in the rear discharge chamber 31 decreases. Along with this, the pressure in the rear concave portion 42 of the second member 38b of the spool 38 decreases, and the biasing force of the spring 48 moves the spool 38 to the rear side.
The movable discharge valve 44 is arranged at the inoperative position as shown in FIG.

According to this embodiment configured as described above, the following effects can be obtained. (A) Movable discharge valve 4 at the start of clutch engagement
While 4 is placed in the inoperative position to the inoperative position,
The refrigerant gas in the compression chamber 23b of the rear cylinder bore 21 is discharged into the discharge chamber 31 with almost no resistance. Therefore, when the clutch is engaged, the rise of the compression load that occurs in the compression chamber 23b in the rear cylinder bore 21 and acts on the piston 22 can be mitigated, and the generation of vibration and noise due to the starting shock can be suppressed. be able to.

(B) At the start of the compression operation, since the movable discharge valve 44 is placed in the inoperative position, the pressure of the refrigerant gas discharged from the rear side compression chamber 23b to the discharge chamber 31 is increased so much. Not not. Here, a part of the discharge pressure in the front-side discharge chamber 29 is supplied into the rear-side discharge chamber 31 via the communication passage 32, and further the pressure introduction passage 49.
Through the second member 38b of the spool 38. Therefore, after the lapse of a predetermined time from the start of the compression operation, the discharge pressure of the rear discharge chamber 31 is surely increased,
This discharge pressure is guided to the back surface of the second member 38b of the spool 38.

On the other hand, when the clutch is disconnected and the discharge of the compressed refrigerant gas to the rear discharge chamber 31 is stopped, the discharge pressure in the rear discharge chamber 31 decreases. Along with this, the pressure on the back surface of the second member 38b of the spool 38 decreases, the spool 38 is moved to the rear side by the urging force of the spring 48, and the movable discharge valve 44 is placed in the inoperative position. Therefore, switching between the inoperative position and the operating position of the movable discharge valve 44 is reliably performed with a simple configuration.

Further, like a conventional variable displacement compressor, an external supply passage for supplying a control pressure to the compressor is connected, and an electromagnetic opening / closing valve is arranged in the external supply passage, and the electromagnetic opening / closing is performed. It is not necessary to provide a control computer for controlling the valve or to arrange a check valve in the discharge passage to complicate the configuration. Therefore, when the clutch is engaged, the structure for alleviating the impact caused by the rapid rise of the compression load and its related configuration are simple and can be manufactured at low cost.

(C) A seal ring 51 is arranged on the outer periphery of the first member 38a of the spool 38. For this reason,
When the spool 38 is moved, the seal ring 51 imparts movement resistance to the spool 38. Therefore, the movable discharge valve 44 is moved from the non-acting position to the working position at a low speed, and the rising of the compression load acting on the piston 22 can be alleviated more effectively.

(D) The dead volume of the compression chamber 23a in the cylinder bore 21 on the front side is reduced by the movable discharge valve 44.
Compression chamber 23b in the rear cylinder bore 21 in which
It is set to be larger than the dead volume of. That is, the front side compression chamber 23a has a larger volume than the rear side compression chamber 23b when the piston 22 reaches the top dead center. Therefore, in the compression chamber 23b in the cylinder bore 21 on the front side, the maximum pressure in the vicinity of the top dead center of the piston 22 is reduced and overcompression is reduced. Therefore, the compression load acting on the piston 22 can be alleviated, and the generation of vibration and noise can be suppressed more effectively.

(E) This dead volume setting is
This is done by forming a recess 52 on the front end surface of the piston 22. Therefore, the dead volume can be easily set.

(F) Rear discharge chamber 31 to spool 3
A pressure introducing passage 49 for guiding the discharge pressure to the rear surface of the casing 8 is composed of a plurality of holes formed in the rear housing 14. Therefore, without using a separate member such as a pipe,
The pressure introducing passage 49 can be easily formed.

(G) A recess 42 is formed on the back surface of the second member 38b of the spool 38, and the discharge pressure introduced from the pressure introducing passage 49 acts on this recess 42 on the back surface. For this reason, it is possible to reliably receive the discharge pressure on the back surface of the spool 38, and to prevent sudden movement of the spool 38 due to the damper action of the gas pressure in the recess 42.

(H) In the pressure introducing passage 49, the throttle portion 5
0 is formed. Therefore, when the discharge pressure is introduced from the rear discharge chamber 31 to the back surface of the spool 38 through the pressure introducing passage 49, the flow of the discharge pressure is reduced by the throttle portion 50.
Is suppressed by Therefore, the movable discharge valve 44 is moved from the inoperative position to the operating position at a low speed, and the piston 22
It is possible to more effectively mitigate the rise of the compression load that acts on.

(Second Embodiment) Next, the second embodiment of the present invention will be described.
The embodiment will be described with reference to FIGS. 4 and 5.
In the second embodiment, the pressure introducing passage 49 including a plurality of grooves is formed on the inner peripheral surface of the cylinder chamber 37. Then, the open / close portions 44a of the retainer 45 and the movable discharge valve 44.
The discharge pressure of the rear discharge chamber 31 is guided to the rear recess 42 of the second member 38b of the spool 38 through the recesses, the pressure introduction passages 49 and the gaps 14b in the rear housing 14. Further, in this embodiment, the seal ring 51 is omitted from the first member 38a of the spool 38.

Therefore, according to this embodiment, the following effects are obtained. (A) Similar to the above-described first embodiment, the compression chamber 23b of the cylinder bore 21 on the rear side is provided until the movable discharge valve 44 is placed from the inoperative position to the operating position at the start of clutch engagement. The refrigerant gas therein is discharged into the discharge chamber 31 with almost no resistance. The sudden rise of the compression load acting on the piston 22 at the start of the compression operation due to the engagement of the clutch can be mitigated, and the generation of vibration and noise can be suppressed. Further, the discharge pressures of the discharge chambers 30 and 31 are guided to the rear surface of the second member 38b of the spool 38, and the switching of the movable discharge valve 44 between the inoperative position and the operating position is reliably performed with a simple configuration. .

(B) The seal ring 51 on the first member 38a of the spool 38 is omitted. Therefore, when the compressor is started, even when the liquid refrigerant is accumulated in the cylinder bore 21, the liquid refrigerant in the rear side cylinder bore 21 has almost no resistance as in the compression operation by connecting the clutch. It is released into 31. Here, when the movable discharge valve 44 is in the inoperative position, the discharge chamber 31 that forms the discharge pressure region and the crank chamber 2 that forms the suction pressure region.
The pressure difference between the liquid refrigerant discharged into the discharge chamber 31 and the liquid pressure discharged from the discharge chamber 31 acts on the liquid refrigerant. Then, the liquid refrigerant in the discharge chamber 31 is introduced into the crank chamber 24 through between the first member 38a of the spool 38 and the inner peripheral wall of the housing chamber 36. Therefore, the inside of the cylinder bore 21 on the rear side is hardly in a so-called liquid compression state, and the generation of vibration and noise can be suppressed.

(C) The pressure introducing passage 49 is composed of a plurality of grooves formed in the rear housing 14. For this reason,
Without using a separate member such as a pipe, the pressure introducing passage 49
Can be easily formed.

The present invention may be modified and embodied as follows. (1) A movable discharge valve 44 is provided corresponding to only one or a specific number of rear discharge holes 43, and a fixed rear discharge valve is provided corresponding to the remaining rear discharge holes 43. thing.

(2) Set the dead volume in the front side compression chamber 23a by forming a recess in the front side valve plate 13 so as to correspond to the front side end surface of each piston 22.

(3) The dead volume in the compression chamber 23a on the front side is set by setting the length of each cylinder bore 21 to be longer on the front side than on the rear side.

(4) The dead volume in the compression chamber 23a on the front side is set by setting the length of each piston 22 so that it is shorter on the front side than on the rear side.

(5) The dead volume in the compression chamber 23a on the front side is formed and set so that the thickness of the front valve plate 13 is smaller than the thickness of the rear valve plate 15.

[0067]

Since the present invention is constructed as described above, it has the following effects. According to the invention described in claim 1, in the compression chamber in the cylinder bore on the rear side, the refrigerant gas in the cylinder bore has almost no resistance from the time when the clutch is connected to the time when the movable discharge valve is placed in the operating position. It is discharged into the discharge chamber. Further, the front side discharge chamber and the rear side discharge chamber are communicated with each other by a communication passage,
A part of the discharge pressure of the front side discharge chamber is introduced into the rear side discharge chamber through this communication passage. Therefore, after a lapse of a predetermined time from the start of operation of the compressor, the discharge pressure of the rear discharge chamber is surely increased, and this discharge pressure is guided to the back surface of the spool. Therefore, the rise of the compression load acting on the piston at the start of the compression operation, that is, the starting shock can be alleviated, and the generation of vibration and noise can be suppressed.

Further, as a drive mechanism for the movable discharge valve, an external supply passage for control pressure, an electromagnetic opening / closing valve in the external supply passage, a control computer, a check valve for the discharge passage, etc. are provided as in the conventional variable displacement compressor. You don't have to. Therefore, the structure of the compressor can be simplified and the compressor can be manufactured at low cost.

When the compressor is started, even when the liquid refrigerant is accumulated in the cylinder bore, the liquid refrigerant in the rear side cylinder bore is discharged into the discharge chamber with almost no resistance, as in the case where the clutch is engaged. It Therefore, the inside of the cylinder bore on the rear side is hardly in a so-called liquid compression state, and the generation of vibration and noise can be suppressed.

According to the second aspect of the present invention, the seal ring imparts a movement resistance to the spool to reduce the moving speed of the movable discharge valve from the inoperative position to the operating position, thereby acting on the piston. It is possible to more effectively mitigate the rise of the compression load that occurs.

According to the third aspect of the present invention, the dead volume of the front side compression chamber is set to be larger than the dead volume of the rear side compression chamber in which the movable discharge valve is arranged. Therefore, the compression load generated in the compression chamber on the front side of the piston can be alleviated. Therefore, generation of vibration and noise can be suppressed more effectively.

According to the fourth aspect of the invention, the pressure introducing passage can be simply constructed by forming the hole or groove in the rear housing. According to the fifth aspect of the present invention, it is possible to reliably receive the discharge pressure in the concave portion on the back surface of the spool, and it is possible to prevent the spool from abruptly moving due to the damper action of the gas pressure in the concave portion.

According to the sixth aspect of the invention, the dead volume can be easily set by forming the recess on the front end surface of the piston. According to the invention described in claim 7, by the throttle portion of the pressure introducing passage,
By suppressing the flow of discharge pressure from the rear discharge chamber to the back of the spool, the moving speed of the movable discharge valve from the inoperative position to the operating position can be reduced, and the rise of the compression load acting on the piston is more effective. Can be relaxed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a double-headed piston type compressor according to a first embodiment.

2 is a partial cross-sectional view taken along line 2-2 of FIG.

FIG. 3 is a partial cross-sectional view showing the state of the movable discharge valve in the operating position of FIG.

FIG. 4 is a partial cross-sectional view showing a double-headed piston type compressor according to a second embodiment.

5 is a partial cross-sectional view taken along line 5-5 of FIG.

[Explanation of symbols]

11: cylinder block, 12: front housing,
13 ... Front valve plate, 14 ... Rear housing, 15 ... Rear valve plate, 18 ... Drive shaft, 21 ... Cylinder bore, 22 ... Double-headed piston, 2
3 ... compression chamber, 24 ... crank chamber forming suction pressure region,
28 ... Front suction chamber, 29 ... Rear suction chamber, 30 ...
Front side discharge chamber, 31 ... Rear side discharge chamber forming discharge pressure region, 32 ... Communication passage, 38 ... Spool, 42 ... Recessed portion,
43 ... Rear side discharge hole, 44 ... Movable discharge valve, 48 ... Spring as biasing means, 49 ... Pressure introduction path, 50 ... Throttling part, 5
1 ... Seal ring, 52 ... Recess

Front page continued (72) Inventor Tomohiro Wakita 2-chome, Toyota-cho, Kariya City, Aichi Stock Company Toyota Industries Corporation (72) Inventor Hiroshi Sato 2-chome, Toyota-cho, Kariya City, Aichi Stock Company Toyota Inside the automatic loom mill

Claims (7)

[Claims] 1. A front housing and a rear housing are joined and fixed to both ends of a cylinder block via valve plates, and a plurality of cylinder bores for accommodating a double-headed piston are formed in the cylinder block. The suction chamber and the discharge chamber are respectively formed in the chamber, and the refrigerant gas is sucked into the cylinder bore from the suction chamber by the reciprocating motion of the piston to be compressed, and then is discharged into the discharge chamber through the discharge hole formed in the valve plate. In a double-headed piston compressor that discharges, a communication passage that connects the front discharge chamber and the rear discharge chamber, a spool movably supported in the discharge chamber of the rear housing, and a rear valve plate Corresponding to at least one discharge hole of the A dynamic discharge valve, an urging means for urging the spool in one direction so that the movable discharge valve is arranged at an inactive position separated from the discharge hole, and the discharge chamber and the discharge chamber in the rear housing. A double-headed piston type compressor equipped with a pressure introduction path communicating with the back surface of the spool. 2. The double-headed piston type compressor according to claim 1, wherein a seal ring for sealing between a suction pressure region and a discharge pressure region is provided on an outer periphery of the spool. 3. A dead volume of a rear cylinder bore whose communication with the discharge chamber is opened / closed by the movable discharge valve is smaller than a dead volume of a front cylinder bore which faces the cylinder bore via the piston. The double-headed piston type compressor according to claim 1, wherein 4. The double-headed piston type compressor according to claim 1, wherein the pressure introducing passage is a hole or a groove formed in the rear housing. 5. The double-headed piston type compressor according to claim 1, wherein a recess is formed on the back surface of the spool. 6. The double-headed piston compressor according to claim 3, wherein the dead volume of the front cylinder bore is set by forming a recess in the front end surface of the piston. 7. The double-headed piston type compressor according to claim 1, wherein a throttle portion is provided in the pressure introducing passage.