JPS6360236B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a suction cutoff device for a vane rotary compressor used in automobile air conditioners and the like.

Conventional configuration and its problems As is well known, in vane rotary compressors, high-pressure lubrication is constantly applied to the bottom of the vane so that as the rotor rotates, the vane rotates and slides with its tip in contact with the inner wall of the cylinder. A structure that allows oil to act is used.

Generally, the means to achieve this are the forced lubrication system, which uses a pump installed on the drive shaft of the compressor to forcibly supply lubrication, and the other, which uses the pressure of high-pressure fluid compressed by the compressor to create a pressure difference between the high and low pressures of the compressor. A differential pressure lubrication system is widely used.

However, in the forced lubrication type, the amount of lubrication increases as the rotation speed of the compressor increases, and this, combined with the centrifugal force acting on the vanes, causes the vanes to be excessively pressed against the cylinder inner wall, causing friction between the vane tips and the cylinder inner wall. This results in an increase in input power to the compressor, which has the disadvantage of deteriorating the durability and efficiency of the compressor.

On the other hand, the differential pressure lubrication type eliminates excessive lubrication, which causes the same drawbacks as the forced lubrication type, and reduces the above phenomenon by providing a mechanism in the lubrication passage to limit the amount of lubrication. .

FIGS. 1 and 2 show a specific configuration of a vane rotary compressor having a conventional differential pressure oil supply system.

In the figure, 1 is a cylinder having a cylindrical inner wall, 2 is a rotor whose outer periphery partially forms a minute gap with the inner wall of the cylinder 1, and 3 is slidably inserted into a vane slot 4 provided in the rotor 2. The plurality of vanes 5 are a drive shaft formed integrally with the rotor 2 and rotatably supported. 6 and 7 are a front side plate and a rear side plate 9 that respectively close both ends of the cylinder 1 to form a working chamber 8 therein;
10 is a suction port communicating with the working chamber 8 on the high pressure side, and 11 is a discharge port 1 communicating with the working chamber 8 on the high pressure side.
A discharge valve 12 is disposed at 0, and a case 12 includes a high-pressure chamber 14 that communicates with a high-pressure passage 13 and is equipped with a screen 15 for separating and capturing lubricating oil in compressed high-pressure fluid. Both ends have a suction pipe connection port 20 and a low pressure passage 19 communicating with the suction port 9. Reference numeral 16 denotes an oil supply passage that communicates the oil reservoir below the high pressure chamber 14 with the vane bottom space 17;
is a passage that limits the amount of oil supplied.

The operation of the vane rotary compressor oil supply system configured as described above will be described below.

When the drive shaft 5 and rotor 2 rotate clockwise in FIG. 2 due to power transmission from a drive source such as an engine, low-pressure fluid flows into the suction port 9.
It flows into the working chamber 8. The high-pressure fluid compressed as the rotor 2 rotates pushes up the discharge valve 11 from the discharge port 10 and passes through the high-pressure passage 13 into the high-pressure chamber 14.
The wet lubricating oil is separated and captured by the screen 15. The lubricating oil separated from the high-pressure fluid is stored below the high-pressure chamber 14, and is supplied to the vane bottom space 17 from the oil supply passage 16 and the passage 18 due to the differential pressure, and is used to press the vane 3.

However, when the compressor is started after a certain period of time has passed since the compressor stopped and the pressure of the fluid on the low pressure side becomes equal to the pressure of the fluid on the high pressure side,
Because the differential pressure immediately after starting the compressor is small, the conventional oil supply system described above causes insufficient pressure on the vanes, especially when the rotational speed at the time of starting the compressor is low, resulting in a well-known problem in which the vanes separate from the inner wall of the cylinder and collide again. This method has the disadvantage that a compression failure phenomenon occurs in which the fluid is not compressed.

Purpose of the Invention The present invention has been made in view of the drawbacks of the conventional oil supply system described above, and is used together with the conventional oil supply system to start the compressor at low speed rotation when there is no or small pressure difference between the high and low pressures of the compressor. However, it is an object of the present invention to provide a suction cutoff device for a vane rotary compressor that can prevent vane malfunctions and poor compression phenomena and does not impair durability or efficiency.

Structure of the Invention In order to achieve this object, the present invention provides a valve body that is slidably disposed in the middle of a suction passage of a vane rotary compressor and that increases or decreases the cross-sectional area of the suction passage by its movement; A portion of the suction passage having the valve body that applies the pressure of each working fluid to the valve body by applying working fluids having different pressures generated by the operation of the compressor to both end faces of the valve body, and during the operation of the compressor. pressure biasing means for applying the pressure of each working fluid to both ends of the valve body to move the valve body in a direction that increases a passage cross-sectional area of the suction passage; It is equipped with a spring that biases the

With this configuration, when the compressor is stopped for a long time and there is no or small pressure difference between the high and low pressures of the compressor, the valve body uses a spring to reduce the cross-sectional area of the suction passage, making it difficult to start the compressor. Immediately after, the valve body continues to reduce the passage cross-sectional area of the suction passage, so fluid is not supplied to the working chamber on the suction side to compensate for the increase in volume of the working chamber due to rotation of the vane. The pressure in the working chamber of will decrease. Therefore, the force acting on the tip of the vane that tends to cause the vane to sink into the vane slot is significantly reduced, so that the vane can be reliably pressed against the inner wall of the cylinder.

In addition, after a certain period of time has passed after startup, when the pressure of the fluid on the discharge side gradually increases and a difference in high and low pressures occurs, the valve body resists the biasing force of the spring and increases the cross-sectional area of the suction passage. As the vane gradually moves in the direction of the cylinder, the pressure in the working chamber on the suction side gradually increases, and the force acting on the tip of the vane does not increase suddenly, so the vane is pressed against the inner wall of the cylinder. normal operation can be continued.

Therefore, even if the compressor is started at a low rotation speed when there is no or only a small pressure difference between the high and low pressures of the compressor, vane malfunctions and poor compression phenomena can be prevented.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 3 and 4 show a vane rotary compressor equipped with a suction cutoff device according to a first embodiment of the present invention. Parts that are the same as those of the machine and have the same functions and effects are designated by the same reference numerals and descriptions thereof will be omitted.

In the figure, 21 is a head cover provided on the upper part of the cylinder 1, which forms a low pressure space such as a suction pipe connection port 20, a suction passage (low pressure passage) 19, and a suction chamber 22, and a head cover chamber 23 on the high pressure side. There is. A sliding chamber 24 is formed across the suction passage 19 and has a stepped portion 25 . A valve body 26 having a stepped portion 27 is slidably arranged in the sliding chamber 24, and the sliding chamber 24 is connected to the first sliding chamber 2.
4a and a second sliding chamber 24b.
The first sliding chamber 24a communicates with the head cover chamber 23 on the high pressure side through a passage 28, and the second sliding chamber 24b communicates with the suction chamber 23 on the low pressure side through a passage 29 and a passage 30 provided in the valve body 26. It communicates with 31
is provided in the second sliding chamber 24b and connects the valve body 26 to the first sliding chamber 24b.
A spring 32 biases the sliding chamber 24a toward the valve body 26.
This is an annular groove with a small passage cross-sectional area that is provided in the suction passage 19 and communicates with the suction passage 19 when the valve body 26 blocks the suction passage 19.

The operation of the vane rotary compressor equipped with the suction cutoff valve configured as described above will be described below.

If a certain period of time has passed since the compressor stopped and the pressure of the fluid on the low pressure side and the pressure of the fluid on the high pressure side are equal, the pressures before and after the valve body 26 are balanced and the valve body 2
6 is the first sliding chamber 24a due to the biasing force of the spring 31.
moving to the side. Therefore, the suction passage 19 communicates with only a small passage cross-sectional area of the annular groove 32.

When the compressor is started in this state, the fluid in the low pressure space downstream of the valve body 26 is sucked into the working chamber 8 by the volume increase of the working chamber 8 on the suction side as the vane 3 rotates. However, because the minimum passage cross-sectional area of the suction passage 19 is the passage cross-sectional area of the annular groove 32 due to the valve body 26, sufficient fluid does not flow, so the pressure in the low-pressure space downstream of the valve body 26 is It declines. At the same time, only a small amount of lubricating oil is supplied to the vane bottom space 17 from the high pressure chamber 14 via the passage 18 and the oil supply passage 16 due to the slight pressure difference due to the increase in the volume of the vane bottom space 17, but inside the aforementioned low pressure space Corresponding to the decrease in pressure, the pressure in the working chamber 8 also decreases, and the force acting on the tip of the vane 3 to force the vane 3 into the vane slot 4 also decreases accordingly. As a result, the vane 3 is pressed against the inner wall of the cylinder 1 and normal operation can be continued.

Further, as the operation continues and the fluid passes through the annular groove 32, is sucked into the working chamber 8 on the suction side, and is discharged, the pressure on the discharge side gradually increases. pressure also increases. As a result, the valve body 26 overcomes the biasing force of the spring 31.
moves toward the second sliding chamber 24b. As a result, the minimum passage cross-sectional area of the suction passage 19 also increases, and the pressure in the working chamber 8 on the low-pressure side increases accordingly, but due to the pressure increase in the high-pressure chamber 14, the pressure is supplied to the vane bottom space 17. The amount of lubricating oil also increases. Therefore, the vane 3 is pressed against the inner wall of the cylinder 1, and normal operation can be further continued.

Furthermore, when the valve body 26 moves to the position shown by the two-dot chain line in FIG.
Its operation is no different from that of the conventional vane rotary compressor.

Therefore, when the compressor is stopped for a long time and there is no or small pressure difference between the high and low pressures of the compressor, the valve body 26 reduces the passage cross-sectional area of the suction passage 19 by the spring 31, and the compressor starts. Immediately after, the valve body 26
Since the cross-sectional area of the suction passage 9 remains reduced, fluid is not supplied into the working chamber 8 on the suction side to compensate for the increase in volume of the working chamber 8 due to the rotation of the vane 3. The pressure in the side working chamber 8 decreases. As a result, the force acting on the tip of the vane 3 to force the vane into the vane slot 4 is significantly reduced, so that the vane can be reliably pressed against the inner wall of the cylinder 1.

Further, after a certain period of time has elapsed after startup, when the pressure of the fluid on the discharge side gradually increases and a difference in pressure between high and low pressures occurs, the valve body 26 resists the biasing force of the spring 3 and the passage cross-sectional area of the suction passage 9 gradually increases in the direction of increasing Therefore, the force acting on the tip of the vane 3 does not increase rapidly, so the vane 3 is pressed against the inner wall of the cylinder 1 and can continue normal operation. Therefore, even if the compressor is started at low speed when there is no or small pressure difference between the high and low pressures of the compressor, it is possible to prevent the vane from malfunctioning.

Next, other embodiments of the present invention will be described with reference to the drawings.

FIG. 5 shows an enlarged cross-sectional view of the essential parts of a suction cutoff device for a vane rotary compressor according to a second embodiment of the present invention, and in the same figure, FIG. The same reference numerals as in the drawings indicate the same parts, and the difference from the first embodiment is that pressure is introduced into the second sliding chamber 24b through a passage 34, and the valve body 26 has an annular shape with a large passage cross-sectional area. Passage 33
It is clear that the same effects as in the first embodiment can be obtained in this case as well.

Note that in the first and second embodiments, the valve body 26
Although the annular groove 32 is provided in the embodiment, an appropriate gap may be provided between the suction passage opening/closing portion of the valve body 26 and the sliding chamber 24, and in the second embodiment, by providing this gap, Needless to say, it is not necessary to provide the passage 34.

Effects of the Invention As is clear from the above explanation, the suction cutoff device for a vane rotary compressor of the present invention can prevent the vane rotary compressor from shutting off even when the compressor has stopped for a long time and there is no or small pressure difference between the high and low pressures of the compressor. can be reliably pressed into contact with the inner wall of the cylinder, resulting in the effect of reliably preventing vane malfunctions and poor compression phenomena.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a conventional vane rotary compressor, Fig. 2 is a plan view of the same compressor with the front side plate removed, and Fig. 3 shows a suction cutoff device according to the first embodiment of the present invention. FIG. 4 is an enlarged cross-sectional view of the main part taken along the line Y--Y in FIG. 3, and FIG. FIG. 2 is an enlarged sectional view of a main part of a vane rotary compressor. 1... Cylinder, 2... Rotor, 3... Vane, 4... Vane slot, 5... Drive shaft, 6...
...Front side plate, 7...Rear side plate, 8...Working chamber, 1
0...Discharge port, 19...Suction passage, 26...Valve body, 28, 30...Passage, 31...Spring.

Claims (1)

[Claims] 1. A cylinder having a cylindrical inner wall, a rotor disposed inside the cylinder and having a part of its outer periphery forming a minute gap with the cylinder inner wall, and a rotor slidably inserted into a vane slot provided in the rotor. a plurality of vanes; a drive shaft formed integrally with the rotor and rotatably supported; a front side plate and a rear side plate that close both ends of the cylinder to form an operating chamber therein; and an outer periphery of the rotor. A base rotary compressor is constituted by a suction passage and a discharge passage communicating with the working chamber across the adjacent portion of the cylinder inner wall, and is slidably disposed in the middle of the suction passage and is moved by its movement. A valve element is used to increase or decrease the passage cross-sectional area of the suction passage, and working fluids with different pressures generated by compressor operation are applied to both end faces of this valve element to apply the pressure of each of the working fluids to the valve element. and, during operation of the compressor, applying the pressure of each of the working fluids to both ends of the valve body so as to move the valve body in a direction that increases the passage cross-sectional area of the portion of the suction passage having the valve body. A suction cutoff device for a vane rotary compressor, comprising: means and a spring that biases a valve body in a direction to reduce a cross-sectional area of the suction passage.