JPH10205443A - Variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent inflow of a liquid refrigerant to a crank chamber when a pressure difference between the crank chamber and a suction chamber is below a given pressure difference. SOLUTION: By changing the inclination angle of a sash plate 5 according to a pressure difference between a crank chamber 3 and a suction chamber 13, a piston stroke is changed to control discharge displacement is controlled. The discharge chamber 14 and the crank chamber are intercommunicated through a first communication passage 18, and opening and closing of a first communication passage is controlled by a pressure control valve 19. Meanwhile, the crank chamber and the suction chamber are intercommunicated through a second communication passage 20, a valve element 22 is arranged in the second communication passage and when a pressure difference between the crank chamber and the suction chamber is decreased to a value lower than a given value, the value element fully closes the second communication passage through the energizing force of the spring 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement compressor used for an air conditioner of a vehicle.

[0002]

2. Description of the Related Art Generally, in a vehicle air conditioner,
A variable displacement compressor is used. As this type of variable displacement compressor, for example, a variable displacement compressor described in Japanese Patent Publication No. 4-74549 (hereinafter referred to as a conventional variable displacement compressor) is known. ing.

A conventional variable displacement compressor is a so-called swinging plate type variable displacement compressor. A rotor is disposed in a crank chamber formed in a compressor casing, and a main shaft is attached to the rotor. A swash plate is attached to the rotor via a hinge mechanism. The main shaft passes through the swash plate, and a sleeve is attached to the swash plate to house the main shaft. A space is formed between the outer peripheral surface of the sleeve and the inner wall surface of the swash plate, and the inclination angle of the swash plate with respect to the main shaft can be changed by a hinge mechanism.

An oscillating plate is disposed on the swash plate via a bearing, and a plurality of piston rods are connected to the oscillating plate by ball connection. In the compressor casing,
A plurality of cylinders are formed at predetermined intervals so as to surround the main shaft, and the piston rod is ball-connected to a piston disposed in the cylinder. In the crank chamber, a guide rod is supported on the compressor casing in parallel with the main shaft, and the guide rod is clamped by one end of the rocking plate. It is swingable in the main axis direction.

[0005] The rotation of the main shaft transmits the rotation of the rotor to the swash plate, whereby the swinging plate performs a so-called swinging motion, and the piston reciprocates to perform a compression operation. As described above, since the inclination angle of the swash plate with respect to the main shaft can be changed by the hinge mechanism, the piston stroke changes by controlling the inclination angle of the swash plate, whereby the compression capacity can be changed. .

The above-described variable displacement compressor is provided with an on-off valve for controlling the opening and closing of an air supply passage from the discharge chamber to the crank chamber so that the suction pressure becomes a predetermined value.
A passage is provided for constantly discharging the discharge gas flowing into the crank chamber from the air supply passage to the suction chamber.

[0007]

Incidentally, the conventional swinging plate type variable displacement compressor has a structure in which the crank chamber and the suction chamber always communicate with each other.
If liquid refrigerant is present on the low pressure side of the refrigeration circuit with the compressor stopped for a long time, the liquid refrigerant may flow into the crank chamber via the suction chamber because the crank chamber and the suction chamber are always in communication. become. In particular, when the temperature inside the vehicle compartment is high and the temperature inside the engine room where the compressor is installed is low, a large amount of liquid refrigerant flows into the crank chamber via the suction chamber.

When the compressor is started in such a state, the opening area of the escape passage is insufficient for the amount of the liquid refrigerant in the crank chamber, and a pressure difference occurs before and after the escape passage to minimize the inclination angle of the swash plate. Will be maintained.
As a result, there is a problem that a desired cooling capacity cannot be obtained until the liquid refrigerant in the crank chamber is sufficiently removed.

An object of the present invention is to provide a variable displacement compressor capable of obtaining a desired cooling capacity at the time of starting the compressor (at the time of starting).

[0010]

According to the present invention, when the pressure difference between the crank chamber and the suction chamber is less than a predetermined pressure, such as when the compressor is stopped, the communication path between the crank chamber and the suction chamber is fully closed, and the communication path is closed. According to the present invention, the liquid refrigerant does not flow into the crank chamber through the crank chamber, the discharge chamber,
A compressor housing having a suction chamber formed therein, and a swash plate disposed in the crank chamber and having a variable inclination angle with respect to the main shaft. The piston is reciprocated by rotating the swash plate according to the rotation of the main shaft. A variable displacement compressor configured to control a discharge displacement by changing a piston stroke by changing a tilt angle of the swash plate according to a pressure difference between the crank chamber and the suction chamber. A first communication passage communicating the chamber with the crank chamber, a valve device for controlling the opening and closing of the first communication passage to adjust the pressure in the crank chamber, and a communication between the crank chamber and the suction chamber; A variable displacement, comprising: a second communication passage, and an on-off valve for completely closing the second communication passage when a pressure difference between the crank chamber and the suction chamber becomes equal to or less than a predetermined value. A compressor is obtained.

For example, the predetermined value is set to be smaller than the pressure difference between the crank chamber and the suction chamber at which the inclination angle of the swash plate starts to change.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

Referring to FIG. 1, a through hole is formed in a central portion of compressor casing 1 and main shaft 2 is formed in this through hole.
Is inserted. The main shaft 2 is rotatably supported on the compressor casing 1 by bearings 1a and 1b.

A crankcase 3 is formed in the compressor casing 1, and a rotor 4 is disposed in the crankcase 3, and the main shaft 2 is attached to the rotor 4. The swash plate 5 is attached to the rotor 4 via a hinge mechanism 41,
The main shaft 2 penetrates the swash plate 5, and the inner wall surface (the contact surface between the swash plate and the main shaft) of the swash plate 5 is in contact with the main shaft 2, and the swash plate 5 is slidable with respect to the main shaft. . The tilt angle of the swash plate 5 with respect to the main shaft 2 can be changed by a hinge mechanism 41.

A swing plate 6 is disposed on the swash plate 5 via a bearing 51, and a plurality of piston rods 7 are connected to the swing plate 6 by ball connection. A plurality of cylinders 8 are formed in the compressor casing 1 at predetermined intervals (angular intervals) so as to surround the main shaft 2, and each piston rod 7 is connected to a piston 9 disposed in the cylinder 8. Is connected to the ball.

In the crankcase 3, a guide rod 10 is supported on the compressor casing 1 in parallel with the main shaft 2, and the guide rod 10 is clamped by one end of a swing plate 6.
Thus, one end of the swing plate 6 can swing in the main shaft direction with respect to the guide rod 10.

A valve plate 11 and a cylinder head 12 are arranged on the right end face of the compressor casing 1 in the drawing, and the right open end of the compressor casing 1 is closed (compressor casing 1).
And the cylinder head 12 constitute a compressor housing). A suction chamber 13 and a discharge chamber 14 are formed in the cylinder head 12. The suction chamber 13 is connected to a suction port 13a, and the discharge chamber 14 is connected to a discharge port (not shown). A suction hole 11a and a discharge hole 11b are formed in the valve plate 11, and the suction chamber 13 and the discharge chamber 14 communicate with the cylinder 8 via the suction hole 11a and the discharge hole 11b, respectively.

At the center of the valve plate 11, a suction valve, a discharge valve (both not shown) and a valve retainer 15 are fixed together by bolts 16 and nuts 17.

A communication passage 18 is formed in the bolt 16 and the cylinder head 12. The communication passage 18 connects the discharge chamber 14 and the crank chamber 3. Communication passage 18
Is provided with a pressure control valve 19 as shown in the figure.
The discharge chamber 14 and the crank chamber 3 communicate with each other.

A communication passage 20 for communicating the crank chamber 3 and the suction chamber 13 is formed in the compressor casing 1, and a valve seat 21 is formed in the communication passage 20 as shown. A valve body 22 is provided on the valve seat 21.
Is biased by a spring 23 in a direction to close the communication passage 20. That is, the valve seat 21, the valve element 22, and the spring 23 constitute an on-off valve that operates in response to a pressure difference between the crank chamber 3 and the suction chamber 13. The spring 23 opens and closes so that the valve body 22 opens and closes with a pressure difference smaller than the pressure difference between the crank chamber 3 and the suction chamber 13 at which the inclination angle of the swash plate 5 starts to change.
Is adjusted. That is, when the pressure difference between the crank chamber 3 and the suction chamber 13 is equal to or less than the predetermined value, the communication passage 20 is fully closed, and the communication between the crank chamber 3 and the suction chamber 13 is cut off.

Next, the structure of the pressure control valve 19 will be described.

The pressure control valve 19 is provided with a valve body 191 for opening and closing the communication passage 18, and the pressure control valve 19 is further provided with a bellows 192. The inside of the bellows 192 is evacuated and provided with a spring, and senses the pressure of the suction chamber 13 through the communication passage 24. A transmission rod 193 is attached to the bellows 192, and the transmission rod 1
The valve 93 drives the valve 191 in accordance with the expansion and contraction of the bellows 192, thereby opening and closing the communication passage 18 (the valve 191 is urged in the valve closing direction by the spring 194). That is, the pressure control valve 19 controls the opening and closing of the valve body 191 in response to the pressure of the suction chamber 13 detected by the bellows 192. The pressure control valve 19 has, for example, the pressure control characteristics shown in FIG. 2, and the suction pressure (Ps) decreases linearly as the discharge pressure (Pd) increases. For example, when the discharge pressure is 15 kg / cm ² G, the suction pressure is 1.7 k
g / cm ² G.

Here, the operation of the variable displacement compressor shown in FIG. 1 will be described.

When the compressor is stopped, the pressure in the refrigeration circuit is balanced.
If g / cm ² G, the pressure control valve 19 has a higher balance pressure than the pressure control characteristic shown in FIG. 2, so that the bellows 192 shrinks and the valve body 191 closes the communication passage 18. Further, since the pressure is in a balanced state, the communication path 20 is blocked by the valve element 22.

Therefore, when the compressor is stopped, the refrigerant is prevented from flowing into the crank chamber. That is, the refrigerant does not flow into the crank chamber 3 from the discharge chamber 14 and the suction chamber 13 through the communication passage 18 and the communication passage 20.

When the compressor is started from the above-described state, the discharge gas is discharged from the crank chamber 3 because the pressure control valve 19 is closed.
And the gas in the crank chamber 3 is only blow-by when the piston 9 compresses the gas. Since the compressor has the minimum non-zero compression capacity, when the pressure in the suction chamber 13 decreases and the pressure difference between the crank chamber 3 and the suction chamber 13 reaches a predetermined value, the valve body 22 opens and the crank The gas in the chamber 3 flows to the suction chamber 13.

As described above, the gas in the crank chamber 3 is only the blow-by gas.
3 is small, and the crank chamber 3 and the suction chamber 13
Does not increase to a pressure difference that changes the inclination angle of the swash plate 5, and therefore, the inclination angle of the swash plate 5 is maximized, and the compressor is operated at the maximum piston stroke.

When the pressure in the suction chamber 13 reaches a predetermined value (for example, suction pressure = 1.7 kg / cm ² G in FIG. 2), the bellows 192 expands and the transmission rod 193
Pushes down the valve element 191 and the communication passage 18 is opened. Therefore, a large amount of discharge gas flows into the crank chamber 3. However, a large amount of gas in the crank chamber 3 cannot be released by the valve element 22, that is, the communication path 20.
The pressure in the crank chamber 3 increases. That is, the pressure difference between the crank chamber 3 and the suction chamber 13 increases to a value greater than or equal to the pressure difference that reduces the inclination angle of the swash plate 5, and as a result, the inclination angle of the swash plate 5 decreases and the piston stroke decreases. .

When the pressure in the suction chamber 13 is to be increased due to the decrease in the piston stroke, the bellows 192 is contracted, and the valve body 191 is operated in the closing direction. Accordingly, the amount of discharge gas introduced from the discharge chamber 14 to the crank chamber 3 decreases, the pressure difference between the crank chamber 3 and the suction chamber 13 decreases, and the inclination angle of the swash plate 5 increases. This increases the piston stroke.

In this way, the opening of the valve body 191 is adjusted so that the pressure in the suction chamber 13 becomes equal to the set pressure of the pressure control valve 19, and the discharge capacity is controlled.

The pressure control valve 1 of the variable displacement compressor shown in FIG.
Reference numeral 9 denotes a so-called internal control type pressure control valve, but a pressure control valve operated by an external signal as shown in FIG. 3 may be used.

The variable displacement compressor shown in FIG. 3 differs from the variable displacement compressor shown in FIG. 1 only in the structure of the pressure control valve. Therefore, here, the structure of the pressure control valve will be described.

Referring to FIG. 3, the illustrated pressure control valve 19
1 includes a valve body 191 that opens and closes the communication passage 18 similarly to the pressure control valve described in relation to FIG. 1, and further, the pressure control valve 19 includes a bellows 192. The inside of the bellows 192 is evacuated and provided with a spring, and senses the pressure of the suction chamber 13 through the communication passage 24.
A transmission rod 193 is attached to the bellows 192, and the transmission rod 193 drives the valve body 191 in accordance with expansion and contraction of the bellows 192, whereby the communication path 18 is opened and closed.

Further, in the illustrated pressure control valve 19, an electromagnetic coil 194 is arranged to face the bellows 192, and a plunger 197 is arranged so as to be surrounded by the electromagnetic coil 194. The plunger 197 is slidably disposed with respect to the electromagnetic coil 194, and a transmission rod 195 is fixed to a tip of the plunger 197. Plunger 19
7 is provided with a spring 196, and the transmission rod 195 presses the valve body 191 in the valve closing direction according to the electromagnetic force of the electromagnetic coil 194 and the urging force of the spring 196.

That is, the pressure control valve 19 responds to the pressure of the suction chamber 13 sensed by the bellows 192,
1 is controlled to open and close. Then, the pressure setting changes depending on the amount of current supplied to the electromagnetic coil 194.

In the above-described example, the oscillating plate type variable displacement compressor has been described as an example. However, the present invention is not limited to the oscillating plate type variable displacement compressor, but may be applied to, for example, a swash plate type variable displacement compressor. The same applies.

[0037]

As described above, according to the present invention, when the pressure difference between the crank chamber and the suction chamber is lower than the pressure difference which can change the inclination angle of the swash plate (predetermined value), the crank chamber and the suction chamber are changed. Communication between the suction chamber and the suction chamber can be prevented from flowing into the crank chamber via the communication passage when the compressor is stopped, thereby smoothly starting up the compressor. There is an effect that it is possible to rise to the maximum compression capacity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a variable displacement compressor according to the present invention.

FIG. 2 is a view showing a pressure control characteristic of the pressure control valve shown in FIG.

FIG. 3 is a sectional view showing another example of the variable displacement compressor according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Compressor casing 2 Main shaft 3 Crank chamber 4 Rotor 5 Swash plate 6 Swinging plate 7 Piston rod 8 Cylinder 9 Piston 10 Guide rod 11 Valve plate 12 Cylinder head 13 Suction chamber 14 Discharge chamber 15 Valve retainer 16 Bolt 17 Nut 18, 20 Communication passage 19 Pressure control valve 21 Valve seat 22 Valve body

Claims (2)

[Claims] 1. A compressor housing having a crank chamber, a discharge chamber, and a suction chamber formed therein, and a swash plate disposed in the crank chamber and having a variable inclination angle with respect to a main shaft, wherein the swash plate is arranged in accordance with rotation of the main shaft. The piston is reciprocated by rotating the swash plate, and the displacement is controlled by changing the piston stroke by changing the inclination angle of the swash plate according to the pressure difference between the crank chamber and the suction chamber. In the variable displacement compressor, a first communication path that communicates the discharge chamber with the crank chamber, a valve device that controls opening and closing of the first communication path to adjust the pressure in the crank chamber, A second communication passage for communicating the crank chamber with the suction chamber, and an opening and closing operation for completely closing the second communication passage when a pressure difference between the crank chamber and the suction chamber becomes equal to or less than a predetermined value. Variable volume characterized by having a valve Quantity compressor. 2. The variable displacement compressor according to claim 1, wherein the predetermined value is set to be smaller than a pressure difference between the crank chamber and the suction chamber at which the inclination angle of the swash plate starts to change. A variable capacity compressor.