JPH11324909A - Variable displacement compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the pressure difference necessary for opening and closing a differential pressure regulating valve in proportion to the discharging pressure by transmitting the discharging pressure as the pressure on the discharging chamber side to the differential pressure regulating valve, and increasing the pressure difference necessary for opening and closing the differential pressure valve when the discharging pressure of the discharging chamber is increased. SOLUTION: A diameter of a valve chamber 103 is reduced in comparison with that of a spring supporting portion 105 to be used as a stopper 107 on the way of the valve chamber 103. An oblique cut 108 is formed for flowing the crank chamber gas to an inlet side even when the spring supporting portion 105 is brought into contact with the stopper 107. Accordingly a groove or the like is formed to the oblique cut 108 so that the crank chamber gas flows therein when the spring supporting portion 105 is brought into contact with the oblique cut 108. By properly varying the valve opening pressure difference condition by the discharging pressure, the controllability and the seizing resistance can be improved, and a differential pressure valve structure can be easily designed and manufactured because it is a mechanical structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor for a refrigerant, and more particularly to a compressor for a refrigerant of a vehicle, an automobile, a general air conditioner and the like.

[0002]

2. Description of the Related Art In a conventional variable displacement compressor using a swash plate, the discharge capacity is determined by the inclination of the swash plate in the crank chamber, while the inclination angle of the swash plate is determined by the pressure in the crank chamber and the suction pressure. Can vary.

That is, as the crank chamber pressure increases, the swash plate inclination angle decreases, and the discharge capacity decreases. Conversely, when the crank chamber pressure decreases, the swash plate inclination angle increases, and the discharge capacity increases.

When the discharge capacity of a variable displacement compressor is to be reduced, the pressure in the crank chamber may become abnormally high. The entire components such as the drive shaft and the rocking plate move in the crank chamber, and the end of the drive shaft abuts against the thrust prevention plate. In this state, the drive shaft rotates, and the thrust prevention plate is severely worn. As a result, the compressor may be damaged.

[0005] In order to avoid such danger, conventionally,
For example, a variable displacement oscillating compressor (Japanese Utility Model 3-1038)
No. 9), a differential pressure valve as shown in FIG. 8 is provided as a safety valve.

That is, in this example, a passage 2 (crank chamber side passage 201 and suction chamber side passage 202) connecting the crank chamber and the suction chamber is provided, and the opening and closing of the safety valve 1 is controlled.

The safety valve 1 comprises a ball valve 101 and a spring 102
When the pressure Pw in the crank chamber exceeds the combined force of the spring force and the pressure Ps in the suction chamber, the ball valve 101
3 side, the fluid flows from the crank chamber to the suction chamber side,
The pressure in the crankcase drops. This prevents abnormally high pressure in the crank chamber.

[0008]

As seen in the prior art, the pressure in the crank chamber may become abnormally high with only the pressure regulating valve, and in such a case, the friction between the drive shaft and the thrust prevention plate is reduced. This may cause damage to the thrust prevention plate and the like.

Further, there is a danger that heat generated from sliding parts in the crank chamber is trapped in the room due to blockage of the pressure control valve due to failure of the pressure control valve or the electric circuit, and damages the compressor.

In order to avoid such a risk, the variable displacement type swash plate compressor is provided with a differential pressure valve, which is connected by a passage between a crank chamber and a suction chamber, and a pressure difference (==) between the crank chamber and the suction chamber. Pw-Ps) opens and closes the differential pressure valve to prevent the crank chamber pressure from becoming abnormally high.

However, the differential pressure valve of the variable displacement oscillating compressor does not open unless a certain pressure difference is exceeded.
However, the differential pressure value between the crank chamber and the suction chamber, which causes damage to the compressor, differs depending on the operating conditions. When the refrigerant circulation amount is large, it does not break even at a high differential pressure value compared to when the refrigerant circulation amount is small. That has been confirmed.

The reason is that when the refrigerant compression amount is large,
This is because the oil circulation into the crankcase is also increased, and the lubrication is rich. Conversely, when the refrigerant circulation amount is small, the supply of lubricating oil into the crankcase is small,
The lubricity is poor.

On the other hand, when the discharge capacity is reduced by forcible rejuvenation or the like, it is necessary to speed up the response when the discharge capacity is large. In other words, a higher crank chamber pressure (differential pressure value) is required. I have.

The problem to be solved by the present invention is as follows.
An object of the present invention is to provide a structure of a differential pressure valve of a variable displacement compressor in which a pressure difference required for opening and closing the differential pressure valve increases in proportion to a discharge pressure. Another object of the present invention is to provide a structure for opening a differential pressure valve without being affected by a discharge pressure when an abnormally high pressure in a crank chamber is attained.

[0015]

In order to solve the problems to be solved by the above-mentioned invention, the capacity is controlled by changing the swash plate angle by the crank chamber pressure, and the pressure in the crank chamber is released to the low pressure side. A variable displacement compressor provided with a differential pressure valve, wherein the differential pressure valve is configured to increase a pressure difference required to open the valve when discharge pressure is high.

Further, in a variable displacement compressor having a differential pressure valve for controlling a capacity by changing a swash plate angle by a crank chamber pressure and releasing the pressure in the crank chamber to a low pressure side, the differential pressure valve is opened. When the pressure of the discharge chamber exceeds a certain value, the pressure of the discharge chamber does not affect the opening and closing of the differential pressure valve. Is provided.

That is, in the present invention, the discharge pressure, which is the pressure on the discharge chamber side, is transmitted to the differential pressure valve, and when the discharge pressure of the discharge chamber increases, the pressure difference required for opening the differential pressure valve also increases. .

In the case where the spring of the differential pressure valve unconditionally contracts as the discharge pressure increases, the differential pressure valve may not be easily opened when the discharge pressure becomes abnormally high. A stopper is provided in the pressure valve, so that when the discharge pressure increases, the end of the spring support portion contacts the stopper to prevent the discharge pressure from affecting the opening and closing of the valve, so that the spring does not contract further. With this configuration, when the pressure in the discharge chamber exceeds a certain allowable range, the pressure difference required for opening the differential pressure valve can be made constant.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 8 shows a conventional variable displacement swash plate type compressor. First, the contents of the differential pressure valve of the present invention are first described from the overall structure of the variable capacity swash plate type compressor shown in FIG. explain.

When the drive shaft 12 rotates, the swash plate 6 attached thereto rotates. The rotation of the swash plate 6 causes the swing plate 7 to swing. The oscillating motion of the oscillating plate 7 is a reciprocating motion of a piston rod 8 connected to the oscillating plate 7, and a piston 10 attached to the other end of the piston rod reciprocates in the cylinder 9.

The gas (refrigerant gas in the case of a cooling device) sucked by the reciprocating motion of the piston 10 is compressed, and the valve body 11 is pushed open to be discharged into the discharge chamber 5. In this compressor structure, the discharge chamber 5 has a two-chamber structure and is connected by a throttle hole 501.

The angle of inclination of the swash plate 6 affects the amount of gas discharged from the piston. For example, when the inclination angle is minimum (the state where the plane of the swash plate and the drive shaft are close to a right angle), the discharge capacity is minimum. Conversely, when the inclination angle is maximum, the discharge capacity is maximum. Become. The swash plate 6 and the swing plate 7 are in contact with each other, and the inclination angle of the swash plate is the inclination angle of the swing plate.

However, while the swash plate rotates, the swinging plate causes the piston rod 8 to reciprocate (reciprocate at the same position). For this reason, since the swash plate and the oscillating plate slide, if lubricating oil is insufficient, frictional heat is generated.

Although the problem to be solved by the present invention has been described, there is a danger that the flow rate of the lubricating oil is insufficient.
2 becomes high when the rotation speed is low and the inclination angle of the swash plate is small. If the compressor is operated for a long time in this state, it causes seizure due to the generation of frictional heat in the sliding portion in the crank chamber and wear of the member due to sliding in a state of poor lubricity. .

Therefore, even when the pressure in the crank chamber is low, the differential pressure valve is opened to allow the gas flow rate to enter and exit.
It is necessary to maintain the lubricity of each member in the crankcase and to lower the temperature. However, if the crankcase is not maintained at a certain high pressure, the rejuvenation response will be delayed. Therefore, a differential pressure valve which is proposed by the present invention and opens in proportion to the pressure of the discharge chamber 5 is required.

The inclination angle of the swash plate is changed by the pressure in the crank chamber, and the pressure is adjusted by the pressure adjusting valve 13.

FIG. 1 shows a compressor provided with a differential pressure valve 1 according to one embodiment, and FIG. 2 shows a sectional view of the differential pressure valve of the present invention. The differential pressure valve 1 includes a ball valve 101,
Spring 102, rod 104, spring support 105, and valve chamber 1
03. A ball valve 10 is provided in the valve chamber 103.
A spring 102 for pressing 1 is supported by a spring support 105 on the other side. The other side of the ball valve 101 shows a crank chamber side passage 201 connected to the crank chamber.

One end of the rod 104 projects into the discharge chamber 5, and when the pressure in the discharge chamber increases, the rod 104 moves in the valve chamber direction.
04 and the spring support 105 move, and the spring 102 contracts. An O-ring 106 is provided for sealing. This differential pressure valve 1 is a differential pressure valve without a stopper function because it does not have a stopper that receives and suppresses the spring support portion 105.

The force applied to the ball valve 101 depends on the crank chamber pressure Pw received through the crank chamber side passage 201 connected to the crank chamber 3 and the suction chamber pressure Ps received through the suction chamber side passage 202 connected to the suction chamber 4. , And the force received by the elastic force of the spring.

When the ball valve 101 is closed, the pressures in the suction chamber 4 and the valve chamber 103 (valve chamber) are the same, and both are Ps (see FIG. 3). Therefore, the condition for opening the ball valve is as follows: ΔP> k (x ₀ −x) / Sw (ΔP = Pw−Ps) Equation 1 where ΔP is the pressure difference, Sw is the cross-sectional area of the passage 201, x ₀
Represents the length of the spring in a natural state (in a state where no force is applied), x represents the length of the spring when the discharge pressure is not applied to the rod 104, and k represents the elastic coefficient of the spring.

In the prior art, the contraction of the spring (= x ₀ −x)
Is constant, and therefore does not open unless the pressure difference ΔP becomes equal to or greater than a certain value. However, in the present invention, since the spring expands and contracts due to the pressure of the discharge chamber, the pressure difference required for opening the valve is variable. That is, as shown in FIG.
When the pressure Pr of the discharge chamber is applied to the head of the rod 104, the spring is newly contracted by △ x, and the length of the spring becomes x '.
When this is expressed by an equation, the cross-sectional area of the rod 104 head is represented by Sr
Then, since the relationship of Pr−Ps = k (x ₀ −x ′) / Sr x ′ = x− △ x P = Pw−Ps holds, the condition for opening the ball valve is ΔP> k ( x ₀ −x ′) / Sw That is, ΔP> (Pr−Ps) Sr / Sw Expression 2.

While the discharge pressure is low, there is no contraction of the spring, and the condition for opening the valve is determined by equation (1). However, when the spring is contracted by the discharge pressure, the condition for opening the valve is expressed by Equation 2. That is, the pressure difference ΔP for opening the valve increases in proportion to the increase in the discharge pressure Pr. As can be seen from the first term of Equation 2, the extent to which the discharge pressure affects the pressure difference required for valve opening is determined by the cross-sectional area Sr of the rod head. This will be determined when designing the differential pressure valve.

Since the pressure Ps in the suction chamber is usually constant, the valve opening is determined by the pressure Pw in the crank chamber.
When the discharge pressure is abnormally high, the pressure in the crank chamber is likely to be abnormally high. Cross-sectional area S
Although it is possible to adjust r so that the valve can be opened even at an abnormal discharge pressure, the influence of the discharge pressure may be lost during normal operation. Therefore, when a certain discharge pressure is reached, the stopper 107 is provided so that a discharge pressure higher than that does not affect the valve opening condition.

FIG. 4A shows the structure of a differential pressure valve having a stopper function according to another embodiment of the present invention. That is, in (1) of FIG.
The diameter of the valve chamber 103 is made smaller than that of the spring support portion 105 to serve as a stopper 107. The oblique cut 108 is for flowing the crank chamber gas to the suction side even when the spring support portion 105 comes into contact with the stopper 107. Therefore, when the spring support portion 105 comes into contact with the oblique cut 108 (FIG. 4).
(2)), a groove or the like is formed in the diagonal cut 108 so that the crank chamber gas flows (a white portion in FIG. 4 is a groove).

Incidentally, as shown in FIG.
Outside of this notch, it is simply a convex portion as a locking portion for simply stopping the spring support portion 105, and a hole diameter for accommodating the spring 102 is larger than a diameter of the spring support portion 105.
The spring 102 may be provided in the middle of the moving direction. As in the case of FIG. 4, the projections are provided at intervals so as to allow several flows to pass therethrough so that the crankcase gas flows.

Further, it is also possible to simply reduce the diameter of the valve chamber 103 to a necessary portion at a required position to be smaller than the diameter of the spring support portion 105 and use the stopper as a stopper 107 to stop the movement of the spring support portion 105.

As shown in FIG. 6, even when the discharge pressure is increased and the rod 104 is pushed in the valve chamber direction, the end of the spring support 105 attached to the rod comes into contact with the stopper 107, The above-described contraction of the spring 102 does not occur. Therefore, the valve opening condition is not affected by the discharge pressure at the point where the spring support portion 105 contacts the stopper.

FIG. 6 is a graph showing the relationship between the valve opening pressure Pw of the differential pressure valve and the discharge pressure Pr. The vertical axis represents the value obtained by subtracting the suction pressure Ps from the crank chamber pressure Pw, and the horizontal axis represents the value obtained by subtracting the suction pressure Ps from the discharge pressure Pr. Range by the discharge pressure Pr until the rod is pushed in the valve opening pressure is constant (equation 1 i.e. Pr over Ps ≦ k (x ₀
-X) / Sr), and when the rod is pushed in, Expression 2 is established, and the discharge pressure Pr increases while affecting the valve opening pressure Pw. When the stopper function is not provided, the graph rises as it is. However, when the stopper function is provided, the graph does not change from the point where the spring supporting portion contacts the stopper (the right end gradient is parallel in FIG. 6). part). That is, the stopper has the function of determining the upper limit of the range exerted by the discharge pressure.

[0039]

The differential pressure valve proposed by the prior art variable displacement swash plate compressor works effectively against abnormal pressure in the crankcase. However, since the valve opening pressure of the differential pressure valve was constant, it was not possible to respond effectively to the problems that occur in the low pressure region and the rejuvenation response (capacity control response) during forced rejuvenation in the high pressure region. However, in the present invention, the valve opening pressure is linked to the discharge pressure, so that the valve can be opened according to the discharge pressure. As a result, the following effects can be obtained.

(1) In an external control type compressor,
When the forced rejuvenation is performed, the valve opening differential pressure can be increased in a region where the discharge pressure is high, so that the response to the rejuice can be sped up.

(2) In the internal control type compressor,
When operated at low outside air temperature, baking does not occur normally, but baking may occur even with a small pressure difference due to lubrication problems.However, using the present invention, it is possible to open the valve even in the region where the discharge pressure is low Thus, the gas flow rate in the crank chamber can be ensured, and the burning can be prevented in order to supply the lubricating oil and lower the temperature.

(3) Since the degree of influence of the discharge pressure can be determined by the size of the cross-sectional area of the rod head and the mounting position of the stopper, the differential pressure valve has a structure that is easy to design.

In summary of the effects of the present invention based on the above points, the effects obtained by the present invention include good controllability and seizure resistance by appropriately varying the valve opening pressure difference condition with the discharge pressure. The differential pressure valve structure is easy to design and manufacture because of its improved and mechanical structure.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the structure of a swash plate type variable displacement compressor according to an embodiment of the present invention.

FIG. 2 is a view for explaining a differential pressure valve without a stopper function according to one embodiment of the present invention.

FIG. 3 is a diagram for mechanically explaining a pressure difference required for valve opening in the embodiment of the present invention.

FIG. 4 is a view for explaining a differential pressure valve with a stopper function according to one embodiment of the present invention, and shows a state in which a spring supporting portion of a rod comes into contact with a stopper and the spring is no longer contracted. FIG.

FIG. 5 is a view for explaining a differential pressure valve with a stopper function according to another embodiment of the present invention.

FIG. 6 is a graph showing a relationship between a valve opening pressure and a discharge pressure of the differential pressure valve according to the embodiment of the present invention.

FIG. 7 is a view for explaining the structure of a variable capacity swash plate type compressor according to the related art.

FIG. 8 is a view for explaining a differential pressure valve of a variable capacity swash plate type compressor according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Differential pressure valve 101 Ball valve 102 Spring 103 Valve room 104 Rod 105 Spring support part 106 O-ring 107 Stopper 108 Oblique cut 2 Passage 201 Crank chamber side passage 202 Suction chamber side passage 3 Crank chamber 4 Suction chamber 5 Discharge chamber 501 Restriction hole 6 Swash plate 7 Swing plate 8 Piston rod 9 Cylinder 10 Piston 11 Valve body 12 Drive shaft (crankshaft) 13 Pressure regulating valve Pw Pressure in crank chamber (crank pressure) Ps Pressure in suction chamber (suction pressure) k Elastic coefficient of spring x Length of the spring (length when the spring is not contracted by the discharge chamber pressure) x Length of the spring ₀ (spring length when no force is applied, natural length) x 'Length of the spring (吐室length when the spring is but occurs contracted by pressure) △ x contraction length of the spring ₍₌ x 0 _-x') pressure Pr discharge chamber (discharge pressure) Sw communication The cross-sectional area of the cross-sectional area Sr rod of

Claims (2)

[Claims] In a variable displacement compressor having a differential pressure valve for controlling a capacity by changing a swash plate angle by a crank chamber pressure and releasing the pressure in the crank chamber to a low pressure side, the differential pressure valve is opened. A variable displacement compressor characterized in that a necessary pressure difference is increased when a discharge pressure is high. 2. A variable displacement compressor having a differential pressure valve for controlling a capacity by changing a swash plate angle by a crank chamber pressure and releasing the pressure in the crank chamber to a low pressure side, the differential pressure valve is opened. When the discharge pressure is higher than a certain value, the pressure in the discharge chamber is increased to open and close the differential pressure valve. A variable displacement compressor characterized by providing a stopper for preventing the influence.