JPH0756257B2 - Variable capacity compressor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable capacity compressor,
In particular, the present invention relates to a variable angle swing swash plate type compressor.

[0002]

2. Description of the Related Art Conventionally, as a compressor for vehicle air conditioning, the crank chamber pressure is adjusted so as to respond to both suction pressure and discharge pressure and change the inclination angle of a rotary drive plate to increase or decrease the compressor discharge capacity (flow rate). Variable displacement wobble plate type variable displacement compressor configured to control with respect to suction pressure (Patent Document 5)
8-158382). When the suction pressure of this compressor decreases due to a decrease in cooling load or high rotation speed,
The bellows of the discharge amount control means expands due to the suction pressure and the balance fluctuation between the discharge pressure and the atmospheric pressure to operate the valve mechanism to reduce the passage area between the suction chamber and the crank chamber, and to reduce the passage between the discharge chamber and the crank chamber. By opening with another valve mechanism, the crank chamber pressure is increased and the differential pressure between the crank chamber pressure and the suction pressure is increased. That is, the pressure acting on the back surface of the piston is increased, thereby reducing the stroke of the piston, preventing the suction pressure from decreasing, and simultaneously reducing the capacity.

[0003]

However, the above-mentioned conventional variable displacement compressor has two valve mechanisms for opening and closing between the suction chamber and the crank chamber and between the discharge chamber and the crank chamber.
Since there are several parts, not only the structure becomes complicated, but also the fluctuation of the crank chamber pressure is large, and the crank chamber pressure rises as the rotation speed increases, which places a load on the seal mechanism. There has been a problem that the surface pressure acting on the part is increased and the sealing property and durability are deteriorated. This decrease in the sealing property occurs even when the engine is rapidly accelerated, because the suction pressure is decreased and the discharge amount control means is operated to increase the crank chamber pressure.

[0004]

In order to solve the above problems, the present invention comprises a suction chamber and a discharge chamber, adjusts the pressure in the crank chamber, and controls the inclination angle of the rotary drive plate to change the compression capacity. In the variable displacement compressor having a capacity control means for controlling the capacity, the capacity control means includes a pressure guide passage communicating the crank chamber and the suction chamber, a valve chamber provided in the head in the middle of the pressure guide passage, and the valve. A valve body for opening and closing a valve hole that is provided inside the chamber and communicates with the suction chamber and the valve chamber; and a pressure detecting means for controlling opening and closing of the valve body, The pressure detecting means includes a bellows that divides and forms the valve chamber into two parts, a spring installed in the bellows, and the valve body attached to the bellows so as to close the valve hole from the crank chamber side. And the opening / closing control of the valve hole by the valve body. It is configured as is done by the relationship between the spring constant of the pressure and the spring of the crank chamber and the pressure of the suction chamber.

[0005]

Since the present invention employs the above means, the opening / closing control of the valve hole by the valve body is performed by the pressure Ps of the suction chamber S, the pressure Pc of the crank chamber C, and the spring constant of the spring installed in the bellows of the pressure detecting means. Depends on the relationship. Therefore, when the pressure Pc of the crank chamber C falls below the set value, the valve mechanism is closed and the gas flow returned from the crank chamber C to the suction chamber S is stopped. Further, when the pressure Pc in the crank chamber C rises and exceeds the set value in this state, the valve mechanism is opened to start the reduction of gas from the crank chamber C to the suction chamber S, and the rise in the crank chamber pressure Pc is suppressed. . Therefore, the pressure acting on the sealing device during operation is not affected by the change in the rotation speed. Further, since the spring constant of the spring is obtained from the relationship between the suction chamber pressure Ps and the crank chamber pressure Pc, the crank chamber pressure Ps is set so that when the suction chamber pressure Ps is large, the crank chamber pressure Ps is low. The balance is achieved where Pc is high, but the control point can be changed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in an angle variable swing swash plate type variable displacement compressor used in a vehicle air conditioner will be described below with reference to FIGS.

As shown in FIG. 1, a bed 3 is joined and fixed to the left end surface of a cylinder block 1 via a valve plate 2, and an annular suction chamber S is formed inside the head 3.
It is connected to the external cooling circuit by the suction port 3a. or,
A discharge chamber D is formed in the center of the head 3 and is also connected to the cooling circuit by a discharge port (not shown).

On the right end surface of the cylinder block 1,
A crankshaft 4 is joined and fixed, and a shaft support hole 1a penetrating through the center of the block 1 and a cylindrical boss 4a integrally formed at the center of the crankcase 4 support a drive shaft 6 by a pair of radial bearings 5. It is rotatably supported. The drive shaft 6 is rotated by the power of the engine via a belt, a pulley and an electromagnetic clutch (not shown). The boss 4
A thrust bearing 7 is interposed between the inner end surface of a and the step portion 6a of the drive shaft 6. A shaft seal chamber 8 is provided in the boss portion 4a, and is communicated with the crank chamber C by a passage 4b penetrating the crankcase 4 for lubrication.

The cylinder block 1 has five axial cylinder chambers 1b (1 in FIG. 1) penetrating therethrough.
One of which is shown in FIG. 3) is provided so as to extend parallel to the drive shaft 6, and these cylinder chambers 1b are spaced at equal angles about the axis of the drive shaft 6 and are concentrically spaced. A piston 10 having a seal 9 is mounted in the angular cylinder chamber 1b so as to be capable of reciprocating sliding movement. A rod 12 is connected to a rear surface of each piston 10 via a spherical joint 11, and a rear end of each rod 12 is connected to a rocking plate 13 received so as to surround the drive shaft 6 via a spherical joint 14. It is connected.

The oscillating plate 13 is supported on the support cylinder portion 15a of the rotary drive plate 15, and its position is regulated by a thrust washer 16 and a stop ring 17 provided at the tip of the rotary drive plate 15a. Between the thrust bearings 18
Is installed. A drive pin 19 is provided on the drive shaft 6 so as to project in the radial direction, and the rotary drive plate 15 is attached to the pin 19 so as to be tiltable in the axial direction by a connecting pin 20 penetrating the tilt guide groove 19a. .

A sleeve 40 is loosely fitted on the drive shaft 6 so as to be located inside the support cylinder portion 15a of the rotary drive plate 15 and slidably on the drive shaft 6 in the axial direction. The support cylinder portion 15a is attached to 40 so as to be tiltable about the engaging pin 41, so that the driving plate 15 can be tilted stably around the connecting pin 20. A recess 40a for protruding the connecting pin 19 is formed in a part of the sleeve 40.

The rocking plate 13 has a guide pin 21 installed in parallel with the drive shaft 6 through an insertion hole 1c of the cylinder block 1 and a locking hole 4c of the crankcase 4, and the guide pin 21.
The ball guide 22 slidably fitted on the upper side and the rocking plate 1
3 so as to be reciprocally slidable in the radial direction, and by a guide shoe 23 that holds the ball guide 22.
It does not rotate together with. The valve plate 2 is formed with a passage 2c that connects the insertion hole 1c with the suction chamber S.

On the other hand, the valve plate 2 is provided with a suction hole 2a for introducing the refrigerant gas from the suction chamber S into the compression chamber in the cylinder chamber 1b, and a suction valve 24 is provided corresponding to the suction hole 2a. It is provided. Similarly, the valve plate 2 is provided with a discharge hole 2b for guiding the refrigerant gas compressed in the cylinder chamber 1b to the discharge chamber D. The discharge valve 25 and the valve retainer 26 are caulked with the caulking pin 27 in correspondence with the discharge hole 2b. It has been installed by.

Next, the control valve 28 for adjusting the pressure in the crank chamber and changing the capacity of the compressor will be described with reference to FIG. In the fitting hole 3b which is formed on one side of the outer periphery of the head 3 so as to communicate with the suction chamber S, a bottomed cylindrical case 29 of the control valve 28 is provided.
It is fitted through a ring 30 and held in place by a stop ring 31. A lid 32 having an air passage 32a is screwed and fixed to an outer end female screw portion 29a of the case 29. A bellows 33 is housed inside the case 29, and the base end portion of the bellows 33 is formed by the inner surface of the lid 32.
It is pressed against the locking step portion 29b with airtightness. A mounting plate 34 is hermetically capped at the tip of the bellows 33, and the bellows 33 and the mounting plate 34 partition the inside of the case 29 into an inner atmosphere chamber A and an outer valve chamber B. A support pin 35 is penetrated and fixed to the mounting plate 34 in the axial direction of the case 29, and a ball valve 36 is fixed to the tip of the support pin 35. Then, the valve chamber B side opening of the valve hole 29c which is provided so as to communicate the suction chamber S and the valve chamber B at the bottom of the case 29 is connected to the ball valve 3
It can be opened and closed by 6. A coil-shaped spring 37 is interposed in the atmosphere chamber A, and the bellows 3
3, the support pin 35 and the ball valve 36 are always provided with the valve hole 29c.
Is urged in the direction to be closed.

A through hole 29d is provided on the outer periphery of the case 29, and an annular groove 29e communicating with the through hole 29d is engraved. The annular groove 29e is provided with the head 3, the valve plate 2 and the cylinder block 1. The communication passage 38 formed in the above section communicates with the shaft support hole 1a of the block 1. Further, the coaxial support hole 1a is communicated with the crank chamber C through a bearing gap of the radial bearing 5 and a communication groove 1d recessed in the rear surface of the block 1, and these through hole 29d, annular groove 29e,
The crank chamber C and the valve chamber B are communicated with each other by a pressure guide path 39 including a shaft support hole 1a, a bearing gap, and a communication groove 1d.
The refrigerant gas in the crank chamber C can be introduced into the valve chamber B.

By the way, the valve hole 2 formed by the ball valve 36
The opening / closing control of 9c is performed by controlling the pressure Ps of the suction chamber S and the crank chamber C.
Pressure Pc, that is, the pressure Pb in the valve chamber B, and the spring 3
This is performed according to the relationship with the spring constant Ko of 7. In this embodiment, when the resultant force of the suction chamber pressure Ps and the crank chamber pressure Pc reaches the set value Pco (2.5 atm), the force Pa of the atmosphere chamber A extends the bellows 33 and the spring 37.
The ball valve 36 is set to operate in the closing direction when the resultant elastic force due to the force is larger than the force that compresses the bellows 33 by the resultant force.

Next, the operation of the swing swash plate type variable displacement compressor configured as described above will be described. In the stopped state of the compressor, the suction pressure Ps, the crank chamber pressure Pc, and the valve chamber B pressure Pb are all balanced at, for example, 5 atm, and the balanced pressure is higher than the pressure Pa (zero atmospheric pressure) of the atmosphere chamber A. Therefore, due to the pressure difference, the bellows 33 is pressed against the elastic force of the spring 37 and is stopped together with the support pin 35 and the ball valve 36 in the direction away from the valve hole 29c. At that time, the drive shaft 6 is driven by the power of the engine.
When is rotated, the drive plate 15 is rotated via the drive pin 19 and the connecting pin 20, whereby the swing plate 13 swings in the front-rear direction without rotating. Then, each piston 10 is reciprocated in the cylinder chamber 1b via the rod 12, the refrigerant gas sucked from the suction chamber S through the suction hole 2a is compressed in the compression chamber of the cylinder chamber 1b, and then discharged from the discharge hole 2b. Pump to chamber D.

On the other hand, during operation of the compressor, compressed gas is blown from the compression chamber to the crank chamber C through the narrow gap between the piston 10 and the inner peripheral surface of the cylinder chamber 1b. It is guided to the valve chamber B through the passage 39, and the valve hole 29
It is returned to the suction chamber S via c and the rise of the crank chamber pressure Pc is suppressed. Further, when the crank chamber pressure Pc decreases from the high pressure state, the pressure Pb in the valve chamber B also decreases, and the ball valve 36 closes the valve hole 29c by the spring 37,
When the pressure Pc in the crank chamber C rises due to the continuously generated blow-by gas due to the closing of the ball valve 36, the balance of the force acting on the bellows 33 is reversed and the ball valve 36 is released from the valve hole 29c. Be surfaced. Therefore, the crank chamber pressure Pc is prevented from rising excessively during the operation of the compressor by repeatedly opening and closing the control valve 28 and adjusting the opening degree.

Now, the moment M about the connecting pin 20 acting on the oscillating plate 13 during the compression operation will be described with reference to FIGS. 3 and 4. FIG. 3 illustrates the piston 10 at the top dead center (compression completed) and the piston 10 at the bottom dead center (complete suction) among the five pistons 10. As is clear from FIG. 3, the piston 1 at the top dead center
Compressive pressure and crank chamber pressure P acting on both front and rear end surfaces of 0
The force by which the oscillating plate 13 pushes backward through the rod 12 due to the pressure difference with c is the maximum, but the central axis O- of the drive shaft 6 is
Since the rejection reasons L1 and L2 from O to the centers of the spherical joint 11 and the connecting pin 20 are substantially equal, the moment M acting on the oscillating plate 13 (the arrow direction in FIG. 3 is positive) can be neglected small.

On the other hand, the spherical joint 14 on the piston 10 side at the bottom dead center has the largest distance L3 from the connecting pin 20, and therefore the suction pressure Ps acting on the front and rear surfaces of the piston 10 and the crank chamber pressure Pc. Differential pressure ΔP (Pc-Ps)
When the suction pressure Ps increases in the suction stroke, the piston 10 is pushed rearward and a positive moment M that tends to increase the stroke acts, and the tilt angle of the oscillating plate 13 increases. . This relationship also acts on the remaining three pistons during the intermediate stroke between the top dead center and the bottom dead center, so that the moment M acting on the oscillating plate 13 in all of the five cylinders 10 is integrated.
Is shown in FIG. 4, for example. As is clear from this figure, the set value Pco of the crank chamber pressure Pc is 2.5
In the case of atmospheric pressure, when the suction pressure Ps is reduced to 2.5 atmospheric pressure, 2.0 atmospheric pressure, 1.5 atmospheric pressure, the total sum of the moments M becomes smaller, and the crank chamber pressure Pc is shown. Under a constant condition, a moment force is generated corresponding to the value of the suction pressure Ps, and the tilt angle of the oscillating plate 13 is determined by this moment force, and the tilt angle changes.

Immediately after the compression operation is started, the suction pressure Ps increases from the balance pressure of 5 atm by the suction operation.
Is suddenly reduced to 4 atm, a differential pressure ΔP (Pc-Ps) between the crank chamber pressure Pc and the suction pressure Ps is generated, whereby the forward moment M acting on the oscillating plate 13 is reduced and the piston is reduced. 10 strokes are reduced and compression capacity is reduced. After that, since the control valve 28 is opened for the crank chamber pressure Pc, the gas is reduced from the crank chamber C to the suction chamber S, and the full capacity operation is performed. Further, when the suction pressure Ps and the crank pressure Pc both decrease and the detected pressure becomes equal to or lower than the set value Pco (2.5 atmospheric pressure), the valve hole 29c of the control valve 28 is closed as described above.

Furthermore, during steady operation, when the rotational speed of the compressor rises, the blow-by gas increases and the crank chamber pressure rises, the ball valve 3 that has closed the valve hole 29c.
When the pushing-down force of the bellows 33 supporting 6 increases, and the pushing-down force becomes larger than the set value, the valve hole 29c of the pressure guiding passage 39 that connects the crank chamber C and the suction chamber S is opened.

As a result, when the pressure in the crank chamber exceeds the set value, the control valve 28 operates so as to lower the crank chamber pressure, so that the pressure Pc acting from the crank chamber C through the passage 4b into the shaft seal chamber 8 is generated. The seal surface pressure is maintained at almost the set value.

[0024]

As described above in detail, according to the present invention, since the valve is opened and closed by the suction pressure Ps and the crank chamber pressure Pc, the fluctuation of the crank chamber pressure can be reduced, so that the shaft seal surface pressure is reduced. Since it can be set to the optimum value, the shaft seal surface pressure can be set to the optimum value, the sealing performance can be improved, and the structure can be simplified by using one valve mechanism. effective.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a central portion showing an embodiment of a variable displacement swash plate type variable displacement compressor according to the present invention.

FIG. 2 is an enlarged cross-sectional view near a control valve.

FIG. 3 is a cross-sectional view for explaining a moment acting on the oscillating plate.

FIG. 4 is a graph showing a moment curve when the rotation angle of the rocking plate is plotted on the horizontal axis and the moment acting on the rocking plate is plotted on the vertical axis, and the suction pressure changes.

[Explanation of symbols]

Cylinder block 1, head 3, crankcase 4,
Drive shaft 6, piston 10, rod 12, swing plate 13, rotary drive plate 15, control valve 28, pressure guide path 39,
Suction pressure Ps, crank chamber pressure Pc, suction chamber S, crank chamber C, atmospheric chamber A, valve chamber B, atmospheric pressure Pa, valve chamber pressure P
b.

Claims (1)

[Claims] 1. A variable displacement compression system comprising a suction chamber (S) and a discharge chamber (D), having a volume control means for adjusting the pressure in the crank chamber and controlling the inclination angle of the rotary drive plate to change the compression volume. In the machine, the capacity control means includes a pressure guiding passage that connects the crank chamber (C) and the suction chamber (S), a valve chamber (B) provided in the head in the middle of the pressure guiding passage, and the valve. A valve element provided in the chamber (B) for opening and closing a valve hole penetratingly provided so as to connect the suction chamber (S) and the valve chamber (B), and opening and closing of the valve element are controlled. For detecting the pressure, the pressure detecting means includes a bellows that divides and forms the valve chamber (B) into two parts, a spring installed in the bellows, and a valve hole attached to the bellows with respect to the valve hole. Consisting of the valve body that is closed from the crank chamber side,
The opening / closing control of the valve hole by the valve body is performed by the relationship between the pressure (Ps) of the suction chamber (S), the pressure (Pc) of the crank chamber (C), and the spring constant of the spring. Variable capacity compressor.