JPH048877A - Variable displacement device for swash plate type compressor - Google Patents

Abstract

PURPOSE:To quickly raise the internal pressure of a swash plate chamber for quickly shifting a piston forward end to the side of a semi-operation position, and improve the controllability of a piston under a low load by opening a high pressure introduction valve at the time of a low load, and introducing high pressure into the swash plate chamber via a high pressure introduction passage. CONSTITUTION:When intake pressure drops to or below the predetermined value, according to the change of a thermal load, an open/close valve mechanism 34 is turned into a close condition, due to the elongation of bellows 34a. In this case, the amount of blowby gas flowing from a compression chamber 27 into a chamber 18 is extremely small. When delivery pressure drops to or below the predetermined value, a check valve 33 opens, and the delivery pressure is introduced from a delivery chamber 29 to a swash plate chamber 13 via a high pressure introduction passage 32. As a result, the internal pressure of the swash plate chamber 13 quickly rises, and a piston forward end 12a quickly shifts to the side of a partial operation position. In compression stroke, compression starts for the first time when a piston body 12b comes in contact with the piston forward end 12a. According to the aforesaid construction, the stroke and capacity of a piston 12 can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a capacity variable device that changes the capacity of a swash plate compressor used in a vehicle air conditioner.

(Prior art) As a capacity variable device for a conventional swash plate compressor,
There is one described in Japanese Patent No.-228680. This device connects a swash plate fixed to a drive shaft, a swash plate chamber in which the swash plate is housed, and a communication path that communicates the swash plate chamber with a suction chamber in response to changes in suction pressure according to heat load. The swash plate includes an on-off valve mechanism that opens and closes to adjust the pressure in the swash plate chamber, a piston that reciprocates when the swash plate rotates, and a cylinder bore in which the piston is slidably accommodated.

A recess is provided in each of the image front ends of the piston,
An adjustment body is fitted into each recess via a spring, and a chamber formed by the recess and the adjustment body communicates with the oblique root chamber.

In the case of this variable capacity device, the weight of the adjustment body is large, so
The controllability of the regulator was poor.

Therefore, the applicant of the present application proposed the following variable capacity device (Japanese Patent Application No. 2-21376).

In the case of this variable capacity device, the tip of the piston is separated from the piston body, the piston tip is formed into a plate shape, the piston tip and the piston body are connected by a spring, and the piston tip and the piston body are connected to each other by a spring. The chamber formed between the swash plate chamber and the swash plate chamber is made to communicate with the swash plate chamber.

(Problem to be solved by the invention) However, since it is difficult to maintain the differential pressure between the swash plate chamber and the suction chamber at low loads, the controllability of the piston is poor, and when the pressure loss due to piping etc. is reduced at low loads, The problem is that it freezes easily.

This invention was made in view of the above circumstances, and its object is to improve the controllability of the piston under low load.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a swash plate fixed to a drive shaft, a swash plate chamber in which the swash plate is housed, and a swash plate chamber and a suction chamber. an opening/closing valve mechanism that opens and closes a communicating passage in accordance with changes in suction pressure according to heat load and adjusts the pressure in the swash plate chamber; a piston that reciprocates when the swash plate rotates; and a piston that slides. a cylinder bore movably housed therein, the tip of the piston being separated from the piston body, the piston tip and the piston body being connected by a spring, and a space between the piston tip and the piston body; In a variable capacity device for a swash plate compressor, the chamber formed is in communication with the swash plate chamber,
providing a high pressure introduction path that communicates the swash plate chamber and the discharge chamber;
A high pressure introduction valve that opens when the difference between the pressure in the swash plate chamber and the pressure in the discharge chamber becomes equal to or less than a predetermined value is provided in the middle of the high pressure introduction path.

(Function) As described above, a high pressure introduction path is provided to communicate the swash plate chamber and the discharge chamber, and a high pressure introduction valve is opened when the difference between the pressure in the swash plate chamber and the pressure in the discharge chamber becomes equal to or less than a predetermined value. is provided in the middle of the high pressure introduction path, so when the high pressure introduction valve opens, high pressure is introduced into the swash plate chamber through the high pressure introduction path, and the internal pressure of the swash plate chamber increases quickly.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a longitudinal sectional view showing a swash plate compressor equipped with a variable capacity device according to an embodiment of the present invention.

In the figure, 1 is the front cylinder block, 2 is the rear cylinder block, and both cylinder blocks 1
．． 2 are bonded to face each other. Both cylinder blocks 1
, 2 has a front head 4 fixed to one end via a valve seat 3, and a rear head 6 to the other end via a valve seat 5. Both cylinder blocks 1, 2
A drive shaft 7 passes through the center of the drive shaft 7, a swash plate 8 is fixed to the drive shaft 7, and the drive shaft 7 and the swash plate 8 are connected to a bearing 9. It is rotatably supported by lO.

The swash plate 8 is housed in a swash plate chamber 13 formed at the joint between the cylinder blocks 1 and 2.

Both cylinder blocks 1 and 2 are provided with a plurality of cylinder bores 11. Each cylinder bore 11 is parallel to the drive shaft 7 and is arranged radially around the drive shaft 7. A piston 12 is slidably accommodated in each cylinder bore 11 .

The image front end +2a of the piston 12 is separated from the piston main body 12b, and the image front end +28 and the piston main body 12b
A coil spring (spring) 26 is disposed between the two. The piston tip 12a is a disk-shaped thin plate, and is smaller and lighter than the piston main body 12b. An annular groove 30 is provided on the outer periphery of the piston tip 12a.

A Teflon-based piston ring 31 is attached to the groove 30 in order to improve the movement of the piston tip 12a and to improve airtightness.

Image tip 12a and piston body 12b of the piston 12
are provided with recesses 16 and 17, respectively, and each recess 16
．． 17 are facing each other. The inner diameters of the innermost parts 16a and 17a of the recesses 16 and 17 are larger than the other parts, and the outer diameters of both ends of the coil spring 26 are also made larger accordingly.
6. ．． 17, both ends of the coil spring 26, which had been contracted in the radial direction, expand and fit into the innermost parts 16a and 17a of the recesses 16 and 17. Piston body 12
A central recess 15 communicating with the swash plate chamber 13 is formed in the center of b. Both surfaces of the swash plate 8 are rotatably engaged in the central recess 15 of the piston body 12b via shoes 14, respectively. The piston body 12b reciprocates within the cylinder bore 11 as the swash plate 8 rotates. The piston tip 12a is connected to the piston body 1 via a spring 26.
Follow 2b.

A chamber 18 is formed between the tip 12a of the piston 12 and the piston body 12b, and the chamber 18 is connected to the piston body 12b.
It communicates with the central recess 15 through through holes 19a and 19b provided in the center.

Both valve seats 3 and 5 have suction ports 3a.

5a and discharge ports 3b, 5b are provided, and an inlet port 3a,
Compression chamber 27 and suction chamber 28 communicate with each other via 5a, and compression chamber 27 and discharge chamber 29 communicate with each other via discharge ports 3b and 5b. Suction valves 20.21 are installed at the suction ports 3a and 5a, and discharge valves 22.23 are installed at the discharge ports 3b and 5b (1).
That's it. The amount of deformation of the discharge valves 22 and 23 is determined by the valve holder 24.
25.

The swash plate chamber 13 communicates with the suction chamber 28 via a communication passage 5c provided in the rear valve plate 5. The rear head 6 is provided with an on-off valve mechanism 34 that controls the pressure Psw in the swash plate chamber 13 by opening and closing the communication passage 5C in accordance with changes in suction pressure depending on the thermal load. A bellows 34a, which is a pressure responsive part of the on-off valve mechanism 34, is provided within the suction chamber 28. When the suction pressure Ps is above a predetermined value, the bellows 34a contracts and becomes an open state, and when the suction pressure Ps is below a predetermined value, the bellows 34a expands and becomes a closed state.

The swash plate chamber 13 and the discharge chamber 29 communicate with each other via a communication passage 32, and as shown in FIG. 1, a check valve (high pressure introduction valve) 33 is provided in the middle of the communication passage 32. .

The check valve 33 includes a locking bottle 33a and a ball valve body 33.
b, and a coil spring 33c that biases the ball valve body 33b toward the hole stopper bottle. When the discharge pressure Pd is below a predetermined value (7 to 8 kg/cn()), the ball valve body 33b
moves away from the valve seat to open the valve, the swash plate chamber 13 and the discharge chamber 29 communicate with each other, and when the discharge pressure Pd exceeds a predetermined value, the ball valve body 33b is pressed against the valve seat against the biasing force of the coil spring 33c. The valve is closed, and the swash plate chamber 13 and the discharge chamber 29 are disconnected from each other.

When the suction pressure Ps exceeds a predetermined value, the on-off valve mechanism 34
The bellows 34a contracts and becomes open (Fig. 2).
. The pressure Psw in the swash plate chamber 13 escapes to the suction chamber 28 through the communication path 5c. Therefore, the pressure Psw in the chamber 18 decreases and becomes almost equal to the suction pressure Ps, and the piston tip 1
2a is pulled by the piston body 12b and moves greatly while maintaining a small distance from the piston body 12b.

Therefore, the stroke amount of the piston tip 12a increases, and the suction amount increases significantly. Since the distance between the piston tip 12a and the piston body 12b at the end of suction is narrow, as soon as the piston body 12b moves during the compression stroke, it hits the piston tip 12a and compression begins. As described above, the stroke amount of the piston 12 increases and the capacity increases.

When the suction pressure Ps becomes equal to or less than a predetermined value in accordance with a change in thermal load, the bellows 34a of the opening/closing valve mechanism 34 expands and enters a closed state (FIG. 3). Although the amount of blow-by gas that flows into the chamber 18 from the compression chamber 27 by the piston ring is extremely small, the discharge pressure Pd is at a predetermined value (7 to 8 kg/cnt).
The check valve 33 opens when the pressure drops below the high pressure introduction path 3.
2, the discharge pressure Pd flows into the swash plate chamber 13 from the discharge chamber 29.

As a result, the internal pressure Psw of the swash plate chamber 13 quickly rises, and the piston tip 12a quickly partially moves toward the operating position. At this time, the piston body +2b and the piston tip 1
2a, the volume of the compression chamber 27 is small. When entering the compression stroke, the piston body 12b enters the compression chamber 27.
Although the piston tip 12a moves to the side, the piston body 12
The piston body 12b does not move until it hits the piston tip 12a, and compression starts only when the piston body 12b hits the piston tip 12a.

In this way, the stroke amount of the piston 12 is reduced, and the capacity is reduced. Furthermore, the above-described high pressure correction increases the suction pressure during low load (Fig. 4), thereby preventing the evaporator from freezing.

(Effects of the Invention) As described above, according to the variable capacity device for a swash plate compressor of the present invention, the swash plate fixed to the drive shaft, the swash plate chamber in which the swash plate is accommodated, and the swash plate chamber. The communication passage that communicates with the suction chamber is opened and closed according to the change in suction pressure according to the heat load,
It includes an on-off valve mechanism that adjusts the pressure in the swash plate chamber, a piston that reciprocates when the swash plate rotates, and a cylinder bore in which the piston is slidably housed, and the tip of the piston is separated from the piston body. capacity of a swash plate compressor that is separated, the piston tip and the piston body are connected by a spring, and a chamber formed between the piston tip and the piston body communicates with the swash plate chamber; In the variable device, a high pressure introduction passage is provided that communicates the swash plate chamber and the discharge chamber, and a high pressure introduction valve that opens when the difference between the pressure in the swash plate chamber and the pressure in the discharge chamber becomes a predetermined value or less is connected to the high pressure Since it is installed in the middle of the introduction path, when the high pressure introduction valve opens during low load, high pressure is introduced into the swash plate chamber through the high pressure introduction path, the internal pressure of the swash plate chamber quickly rises, and the tip of the piston is placed in the half-operated position. move quickly to Therefore, the controllability of the piston at low loads is further improved, and the risk of freezing of the evaporator is eliminated.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a variable capacity device according to an embodiment of the present invention, FIGS. 2 and 3 are longitudinal sectional views of a swash plate compressor equipped with a variable capacity device according to an embodiment of the present invention, FIG. 4 is a diagram for explaining the operating characteristics of the check valve. 5c...Communication path, 7...Drive shaft, 8...Swash plate, 1
1... Cylinder bore, 12... Piston, 12a.
... Piston tip, 12b... Piston body, 13
...Swash plate chamber, 18...Chamber, 34...Opening/closing valve mechanism, 2
6...Coil spring (spring), 28...
Suction chamber, 29...Discharge chamber, 32...High pressure introduction path, 3
3. Check valve (high pressure introduction valve). Akira 1 bad

Claims (1)

[Claims] 1. A swash plate fixed to the drive shaft, a swash plate chamber in which the swash plate is housed, and a communication passage connecting the swash plate chamber and the suction chamber are opened and closed in accordance with changes in suction pressure according to heat load, It includes an on-off valve mechanism that adjusts the pressure in the swash plate chamber, a piston that reciprocates when the swash plate rotates, and a cylinder bore in which the piston is slidably housed, and the tip of the piston is separated from the piston body. capacity of a swash plate compressor that is separated, the piston tip and the piston body are connected by a spring, and a chamber formed between the piston tip and the piston body communicates with the swash plate chamber; In the variable device, a high pressure introduction passage is provided that communicates the swash plate chamber and the discharge chamber, and a high pressure introduction valve that opens when the difference between the pressure in the swash plate chamber and the pressure in the discharge chamber becomes a predetermined value or less is connected to the high pressure A variable capacity device for a swash plate compressor characterized by being installed in the middle of an introduction path.