JPH11280658A - Capacity control valve of variable capacity compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a large load from being momentarily applied to the bellows and improve the durability and reliability of a capacity control valve by a structure which does not respond immediately to a momentary pressure change in the discharge chamber. SOLUTION: This control valve is composed of a valve casing 1, a bellows 2 arranged within this valve casing 1, which makes the inner portion a vacuum and which is provided with a spring, an adjustment screw 3 fixed to the bottom end portion of this bellows 2 to adjust the amount of expansion of the bellows 2, a valve body 5 to open and close a communicating passage 40 between a crank chamber and an intake chamber according to the expansion of the bellows, a moveable transmission rod 6 which receives the discharge chamber pressure, a stopper 7 fixed to one end of the transmission rod 6, a spring 8 interposed between the stopper 7 and the valve body 5, which energizes the transmission rod 6 upward, and a rod cover 9 fixed to the valve casing 1 and formed so as to cover the transmission rod 6. An orifice 100 is formed in this rod cover 9, which enables one end of the transmission rod 6 to receive the discharge chamber pressure.

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 air conditioners for vehicles, automobiles and general use.

[0002]

2. Description of the Related Art For example, Japanese Patent Publication No. 3-53474 discloses a swash plate type variable displacement compressor. The compressor converts the rotational motion of the swash plate into the oscillating motion of the oscillating plate and causes the piston to reciprocate.However, the pressure in the crank chamber is adjusted to change the inclination angle of the piston. Thus, the compression capacity is changed by changing the stroke of the piston.

Next, the control valve will be described with reference to FIG. A communication passage 4 communicating with the pressure of the crank chamber is formed, and a pedestal 20 having a hole 201 is attached to the other end. Inside the valve chamber 10, there is a bellows 2 having a substantially vacuum inside, and a protruding portion of the bellows 2 is attached with an adjusting screw 3 at a lower end of the valve chamber. A valve body 5 is provided at the tip of the bellows 2, and the valve body 5 opens and closes a hole 201 communicating with the suction chamber of the pedestal 20.

The pedestal 20 is provided with a valve cylinder 14 communicating with the discharge chamber 11. The valve cylinder 14 is connected to a suction valve 130, a valve plate 13, a discharge valve 131, and a retainer and a bolt 15. They are fixed together. The transmission rod 6 is slidably inserted into the valve cylinder 14, and the transmission rod 6 is sealed by a seal member 102. The transmission rod 6 is pushed up by a spring 8, and the other end of the spring 8 is in contact with the valve body 5.

The gas in the crank chamber passes from the communication passage 4 into the valve chamber 10, passes through the valve element 5, passes through the hole 201, passes through the communication passage 40, and reaches the suction chamber. The transmission rod 6 is pressed against the spring 8 by the discharge pressure of the discharge chamber 11. This force is applied to the valve element 5, and the valve element 5 opens as the pressure in the discharge chamber increases. As a result, as the discharge pressure increases, the crank chamber communicates with the suction chamber, and the crank chamber pressure decreases. In order to decrease the capacity, the inclination angle of the swash plate is increased to increase the capacity.

In this conventional example, only the communication between the suction chamber and the crank chamber is controlled, and the pressure in the discharge chamber is fed back to this control.

[0007]

When the compressor is started while the liquid refrigerant is stopped on the compressor suction side, the compressor enters a liquid compression state. At this time, the discharge chamber pressure instantaneously becomes abnormally high. (Eg, 100 kg / cm ² G or more).

At this time, in the control device of the prior art shown in FIG. 3, the transmission rod 6 instantaneously moves by overcoming the urging force of the spring 8, and the tip of the transmission rod 6 strikes the valve element 5 and the bellows 2 Excessive loads will be applied, and there is no corresponding protection mechanism against this abnormal pressure.

When this liquid compression state is repeated, the expansion and contraction characteristics of the bellows 2 change, and the operating point of the control device lowers.
Normal operation can be hindered and in some cases freezing can occur in the evaporator.

In order to solve the above-mentioned conventional problems, according to the present invention, a capacity control valve of a variable displacement compressor for protecting against sudden abnormal pressure, for example, even in the state of liquid compression, is provided. The purpose is to obtain the structure.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention is designed so that an excessive load is not applied to a bellows even in a liquid compression state, and comprises a discharge chamber, a suction chamber and a crank chamber. A displacement control valve for a variable displacement compressor that controls a piston stroke by adjusting a pressure, comprising: a pressure-sensitive member that expands and contracts by sensing the suction chamber pressure or the crank chamber pressure; A valve body that operates in response to open and close a communication passage between the crank chamber and the suction chamber, and shifts the opening / closing operation point of the valve body by applying a load generated by the pressure of the discharge chamber to the valve body. Operating point control means to be operated, and a discharge chamber pressure receiving portion of the operating point control means disposed in a pressure chamber defining a discharge chamber, and an orifice communicating the pressure chamber with the discharge chamber. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on embodiments with reference to the drawings.

As shown in FIG. 1, the displacement control valve according to the present invention comprises a valve casing 1, a bellows 2 disposed inside the valve casing 1, the inside of which is evacuated, and a spring disposed therein.
An adjusting screw 3 fixed to the lower end of the bellows 2 in the figure to adjust the amount of expansion and contraction of the bellows 2, A valve body 5 for opening and closing the communication passage 40, a transmission rod 6 movable by receiving a discharge chamber pressure, a stopper 7 fixed to one end of the transmission rod 6, and interposed between the stopper 7 and the valve body 5; It comprises a spring 8 for urging the transmission rod 6 upward in the figure, and a rod cover 9 fixed to the valve casing 1 and formed so as to cover the transmission rod 6.

The rod cover 9 has an orifice 100
The orifice 100 allows the negative end of the transmission rod 6 to receive the discharge chamber pressure.

The rod cover 9 forms a kind of pressure chamber 101 as described above, and the pressure from the discharge chamber 11 has a buffering function through the orifice 100, so that it does not directly receive a sudden pressure change. .

The bellows 2 receives the pressure of the crank chamber 12, and the upper part of the valve element 5 receives the pressure of the suction chamber through a communication passage 40.

The variable displacement compressor using the displacement control valve shown in FIG. 1 operates to substantially control the suction chamber pressure as shown in FIG. It changes depending on the chamber pressure.

When the discharge chamber pressure increases, the transmission rod 6
Moves downward in the figure overcoming the urging force of the spring 8 and acts on the valve element 5. Then, the load due to the discharge chamber pressure increases.

As shown in FIG. 2, when the discharge chamber pressure increases, the operating point decreases. Conversely, when the discharge chamber pressure decreases, the transmission rod 6 moves upward in the drawing, the load due to the discharge chamber pressure acting on the valve element 5 decreases, and the operating point rises.
When the discharge chamber pressure falls below a predetermined state, the stopper 7 comes into contact with the valve casing 1.
The operating point is constant without being affected by the discharge chamber pressure.

When the variable capacity compressor is started in a state where the liquid refrigerant is present on the suction side, the compressor enters a liquid compression state, and the discharge chamber instantaneously becomes abnormally high in pressure. The pressure is reduced at the orifice 100 and excessive pressure is instantaneously applied to the transmission rod 6.
Will not join. That is, due to the pressure reducing action at the orifice 100, the transmission rod 6 hardly responds to an instantaneous change in the discharge chamber pressure, and operates in response to a gradual change in the discharge chamber pressure.

The volume of the pressure chamber 101 and the diameter of the orifice
Experiments are performed to determine what is appropriate for the discharge pressure, so that a person skilled in the art can select an efficient one.

That is, some of the pressure chambers 101 having different volumes and orifices having different diameters can be easily prepared, and the pressure chambers 101 can be detachably replaced immediately.

In addition, the present invention can be used for other compressors which produce a sudden liquid compression state and cause pressure fluctuations.

[0024]

The effects of the present invention will be described below with the above configuration.

Since the structure does not immediately respond to an instantaneous pressure change in the discharge chamber, an excessive load is not instantaneously applied to the bellows, and the durability of the displacement control valve is improved.

With a very simple structure, even if the discharge pressure becomes abnormally high due to the liquid compression state, the protection function is provided without causing the bellows or the like to repeatedly change the characteristics.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a displacement control valve of a variable displacement compressor according to the present invention.

FIG. 2 shows pressure control characteristics of the capacity control valve of the embodiment of FIG.

FIG. 3 shows a conventional example of a variable displacement compressor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve casing 2 Bellows 3 Adjusting screw 4 Communication path (crank chamber) 40 Communication path (suction chamber) 5 Valve 6 Transmission rod 7 Stopper 8 Spring 9 Rod cover 10 Valve chamber 100 Orifice 101 Pressure chamber 102 Seal member 11 Discharge chamber 13 Valve plate 130 Suction valve 14 Valve cylinder 15 Bolt 20 Pedestal 201 Hole

[Procedure amendment]

[Submission date] March 10, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0002

[Correction method] Change

[Correction contents]

[0002]

2. Description of the Related Art For example, Japanese Patent Publication No. 3-53474 discloses a swash plate type variable displacement compressor. The compressor converts the rotational motion of the swash plate into the oscillating motion of the oscillating plate and causes the piston to reciprocate.However, by adjusting the pressure in the crank chamber, the inclination angle of the swash plate is reduced. In other words, the compression capacity is changed by changing the stroke of the piston.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction contents]

The pedestal 20 is provided with a valve cylinder 14 that communicates with the discharge chamber 11. The valve cylinder 14 is connected to a suction valve 130, a valve plate 13, a discharge valve 131, and a retainer and a nut 15. They are fixed together. The transmission rod 6 is slidably inserted into the valve cylinder 14, and the transmission rod 6 is sealed by a seal member 102. The transmission rod 6 is pushed up by a spring 8, and the other end of the spring 8 is in contact with the valve body 5.

Claims (1)

[Claims] 1. A displacement control valve for a variable displacement compressor having a discharge chamber, a suction chamber, and a crank chamber and controlling a piston stroke by adjusting a crank chamber pressure, wherein the suction chamber pressure or the crank chamber pressure is controlled. A pressure-sensitive member that expands and contracts by sensing the pressure-sensitive member, and operates in response to expansion and contraction of the pressure-sensitive member,
A valve element for opening and closing a communication passage between the crank chamber and the suction chamber, and an operating point control means for applying a load generated by the pressure of the discharge chamber to the valve element to shift an opening and closing operating point of the valve element. A variable displacement compressor comprising: a discharge chamber pressure receiving portion of the operating point control means disposed in a pressure chamber defining a discharge chamber; and an orifice communicating the pressure chamber with the discharge chamber. Capacity control valve.