JP2001090683A - Intake control valve for oil-cooled compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an intake control valve for screw compressor capable of quickly closing an intake flow passage while working as a check valve when a compressor body is stopped, capable of optimally controlling open degree of a valve element when operating the valve element for full close, full open and an intermediate degree of opening when load is fluctuated during the operation of a compressor body without generating the hunting with the noise, and capable of preventing the generation of noise with the vibration of the valve element due to the vibration of the compressor body. SOLUTION: In this intake control valve 1 for screw compressor, a vertical through hole 2 is provided in a guide bar 37 positioned outside of a recessed part 36 at the center of a valve element 21, and a long hole 3 for communicating the bottom part of the recessed part 36 with the through hole 2 is provided in the guide bar 37, and a check valve part 4 allowing the only flow of the fluid directed upward is formed over a junction part of the through hole 2 and the long hole 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control valve of a screw compressor which operates using its own discharge gas without relying on an external power source.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, there has been known an oil-cooled screw compressor using an intake control valve 11 which operates using its own discharge gas without relying on an external power source. The intake control valve 11 is provided in a suction passage 13 of the screw compressor main body 12. Screw compressor body 1
An oil separation / recovery device 15 and a check valve 16 functioning as a pressure holding valve are interposed in a discharge flow path 14 extending from the oil separation / recovery device 2. Oil is supplied to a bearing / shaft seal portion, a gas compression space, and the like in the compressor body 12.

The intake control valve 11 has a valve seat 22 with which a valve element 21 abuts, and an upstream suction space 23 opened and closed by the valve element 21 and a screw compression from a portion of the valve element 21 and the valve seat 22. A downstream suction space 24 extending to the machine body 12,
The downstream suction space 24 includes a first space 26 separated by a diaphragm 25, and the first space 26 includes a cylinder 28 separated by a partition wall 27. The upstream suction space 23 and the downstream suction space 24 form a part of the suction flow path 13. In the case of an air compressor, a suction filter (not shown) is provided at the inlet of the upstream suction space 23. Is provided. Further, a piston member 32 constantly urged toward the partition wall 27 by a coil spring 31 is slidably fitted in the cylinder portion 28, and the space in the cylinder portion 28 is partitioned by the piston member 32. The second space 33 on the side and the third space 34 on the opposite side are separated from each other. The third space 34 is always open to the atmosphere through the through hole 35. A check valve 51 is provided between the through hole 35 and the atmosphere to allow only a flow from the atmosphere to the through hole 35.

The valve body 21 has a hat-shaped cross section and has a concave portion 36 at the center, while a guide member 37 projects from the center of the upstream suction space 23 into the downstream suction space 24. . The guide member 37 is fitted in the recess 36 with a bushing interposed therebetween, and the valve element 21 can advance and retreat along the guide member 37. In addition, the guide member 37 penetrates through the diaphragm 25 and the partition wall 27.
A piston rod 38 coaxial with the piston rod 38 is provided. The diaphragm 25 and the piston rod 38 are fixed at the penetrating portion, and the piston rod 38 and the piston member 32 are also fixed so as to be integrally operable. The piston rod 38 is provided so as to be able to advance and retreat while maintaining airtightness at a portion where the piston rod 38 penetrates. A coil spring 39 is provided between the valve body 21 and a fixed portion between the diaphragm 25 and the piston rod 38.
Is interposed. As shown in FIG. 5, the coil spring 39 is configured such that when the valve element 21 is in contact with the piston rod 38, a force acts in a direction in which the valve element 21 moves toward the valve seat 22. Have been.

On the other hand, the first branch flow path 4 branched from the discharge flow path 14 between the oil separation / recovery unit 15 and the check valve 16
1 and a second branch channel 42 are provided. The first branch flow path 41 is connected to the upstream suction space 23 through the air release valve 43.
, And the second branch channel 42 communicates with the first space 26 via a pressure control valve 44. Oil separation and recovery unit 1
A channel 45 extends from 5, and this channel 45 communicates with the second space 33. Further, the first space portion 26 and the downstream suction space portion 24 communicate with each other by a bypass flow passage 47 provided with an orifice.

The third space portion 34 and the downstream suction space portion 24 are configured to be able to communicate with each other through a bypass passage 50 provided with an orifice. The piston member 32 is the partition 27
In the bypass passage 50, the third space portion 34 and the downstream suction space portion 24 are in communication with each other, and the piston member 32 is in the state shown in FIG. When moving in the opposite direction to the partition 27,
The opening of the bypass passage 50 on the third space portion 34 side is closed by the piston member 32, and the third space portion 34 and the downstream suction space portion 24 are in a non-communication state.

When the oil separator / collector 15 is at substantially atmospheric pressure, the second space 33 is also at approximately atmospheric pressure via the flow path 45, and the pressure adjusting valve 44 is closed, the screw compressor main body 12 is closed. Is started. At this time, the piston member 3
2 moves toward the partition wall 27 by the force urged by the spring 31, and the valve element 21 is pressed against the valve seat 22. The third space 34 and the downstream suction space 24
And a small amount of air flows from the third space portion 34 to the downstream suction space portion 24 via the bypass flow passage 50, and the screw compressor body 1
It is compressed at 2 (almost no-load operation).

Next, the internal pressure of the oil separation and recovery unit 15 gradually increases, and the internal pressure of the second space 33 into which the discharge gas is guided through the flow passage 45 also increases.
The valve body 21 moves in a direction away from the valve seat 22 to be in the state shown in FIG. 5, enters a full load operation, and enters the screw compressor body 12 via the upstream suction space 23 and the downstream suction space 24. Gas will be inhaled. The sucked gas is compressed while receiving oil injection from the oil supply passage 18, and the compressed gas is compressed together with oil into the screw compressor main body 12.
Is discharged toward the oil separation / recovery device 15 from the discharge port. In the oil separation and recovery unit 15, the compressed gas and the oil are separated, and the oil temporarily stays in the oil sump 17 and is supplied from the oil supply passage 18 to the bearing / shaft seal, the gas compression space, and the like. The gas is sent out to a portion of the discharge channel 14 connected to the upper part of the oil separation and recovery unit 15.

During operation of the compressor, when the load decreases due to a decrease in the amount of air used or the like, the discharge pressure increases, and when the discharge pressure exceeds the set value of the pressure control valve 44, the pressure control valve 44 opens. A part of the discharge gas is guided to the first space 26, and the first space 26, which is in communication with the downstream suction space 24 by the bypass flow path 47 having the orifice, has a discharge pressure, a suction pressure, Intermediate pressure between the two. As a result, the diaphragm 25 and the piston rod 38 are pushed to the valve seat 22 side, and the valve element 21 approaches the valve seat 22 according to the magnitude of the intermediate pressure. Then, the cross section of the flow path from the upstream suction space 23 to the downstream suction space 24 is narrowed, and the compressor enters a partial load operation state. further,
If the discharge pressure continues to rise, the valve body 21 eventually becomes the valve seat 22.
, The intake control valve 11 is fully closed, and the compressor is in a no-load operation state.

Basically, in this compressor, the above-described capacity adjustment operation is performed. When the pressure adjustment valve 44 is open, the on / off control for energy saving described below is performed by the control device. It is performed by The volume up to and including the gas flow space in a predetermined range on the discharge side of the screw compressor main body 12, for example, from the discharge port of the screw compressor main body 12 to the reserve tank (not shown) is determined in advance. Then, the control unit calculates the compression per unit time at the present time, which is calculated based on this volume, the suction pressure and the opening degree of the intake control valve 11 obtained from the pressure at the secondary side of the check valve 16. The amount of compressed gas used is calculated from the gas supply amount, that is, the compressed gas supply rate. Furthermore, assuming that there is no new gas supply, the descent time required for the discharge pressure to drop from the current state to the lower limit pressure set value, that is, the return pressure, for example, 6 kgf / cm ² G, is calculated. When the descent time is shorter than a set time, for example, 1 minute, the screw compressor main body 12 is not stopped even if the pressure on the secondary side of the check valve 16 exceeds the upper limit pressure set value. I do.

Therefore, the above-described calculation of the time is repeatedly performed. If the descent time exceeds one minute and the pressure on the secondary side exceeds the upper limit pressure set value, the screw compressor main body 12 is stopped. When this is done, the valve element 21 immediately moves by the force of the coil spring 39 and sits on the valve seat 22, and the flow path between the upstream suction space 23 and the downstream suction space 24 is closed. Then, with the air release valve 43 opened, the discharge gas in the portion of the discharge flow path 14 on the primary side of the check valve 16 is returned to the upstream suction space 23 via the first branch flow path 41. In the case of an air compressor, the recirculated compressed air is released to the atmosphere.

The downstream suction space 24, the suction passage 13, the screw compressor main body 12, the oil separator / collector 15, and the second space 33 are at atmospheric pressure, and the piston member 32 and the piston rod 38 are connected to the valve seat 22. , The diaphragm 25 is deformed in a convex shape toward the valve seat 22, and the valve body 21 comes into close contact with the valve seat 22. In this way, the stop time of the screw compressor main body 12 is ensured at least for at least the set time, for example, at least one minute. And the screw compressor body 1
When the discharge pressure drops to the above-mentioned return pressure after the stop of Step 2, the discharge valve 43 is closed, and the screw compressor main body 12 is restarted.

[0013]

When the load on the discharge side of the screw compressor main body 12 fluctuates drastically in the case of the above-mentioned conventional apparatus, the valve 21 is moved away from the valve seat 22 or in the opposite direction. A large external force acts to move. However, the gap between the bushing in the recess 36 and the guide rod 37 is small, and in FIG.
When the space in the recess 36 on the right end side is rapidly expanded or conversely reduced rapidly, a resistance force against the external force acts on the guide rod 37 from the space in the recess 36. . Therefore, the guide rod 37 operates only slowly. For example, when the load is rapidly reduced and the screw compressor main body 12 is to be stopped, the operation of the valve body 21 as the check valve is delayed, and This causes a problem that the compressed gas or the lubricating oil flows backward, leaks outside through the intake control valve 11, and contaminates the periphery of the compressor.

On the other hand, a groove extending in the axial direction of the guide rod 37 is formed in the inner periphery of the bushing to improve the flow of air between the bottom space in the recess 37 and the outside. An intake control valve is also used. In the case of this intake control valve, when the valve body 21 is to be quickly operated, the above-described resistance force is lost, but when a large external force acts on the valve body 21 due to the above-described rapid load change, the valve body 21 21
The braking force no longer acts on. Therefore, for example, when the intake control valve 11 is closed, there is a problem that the valve body 21 comes into tight contact with the valve seat 22 to cause hunting and generate abnormal noise. In addition, there is a problem that the valve body 21 operates even by a slight load fluctuation on the discharge side or a vibration of the compressor, so that abnormal noise is easily generated. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems, and it is possible to immediately close the suction passage as a check valve when the compressor main body is stopped, and to further reduce the load during operation of the compressor main body. Even when the valve body is operated to the fully-closed, fully-opened, and intermediately-opened positions during the fluctuation, the above-mentioned openness can be properly controlled without causing hunting accompanied by abnormal noise, which is caused by vibration of the compressor body. It is an object of the present invention to provide an intake control valve for a screw compressor, which can also prevent generation of abnormal noise due to run-out of a valve body.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a suction passage comprising an upstream suction space portion and a downstream suction space portion following the upstream suction space portion. An annular protrusion that forms a valve seat is provided at an end on the downstream side suction space side, and from the upstream suction space toward the downstream suction space at the center of the valve seat,
And a guide is protruded vertically to the surface of the valve seat,
A valve body cooperating with the valve seat in the downstream suction space portion is provided so as to be movable along the guide member which is relatively slidably fitted into a recess at the center thereof, The piston rod for actuating the piston is protruded into the downstream suction space so as to be movable in parallel with the axis of the guide, and the top of the valve body contacts the end of the piston rod. In the intake control valve of the screw compressor provided with a spring means for urging the valve body toward the valve seat, a vertical through hole is formed in a portion of the guide rod outside the recess, and A check hole for perforating a long hole for communicating the bottom of the recess with the through hole and allowing only a gas flow upward to a portion above a junction of the through hole and the long hole; Part was formed.

[0016]

Next, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show an intake control valve 1 of an oil-cooled compressor according to the present invention. Portions common to those of the apparatus shown in FIG. In the intake control valve 1, a through hole 2 in the vertical direction is formed in a portion of the guide rod 37 outside the recess 36, and an elongated hole 3 that connects the bottom of the recess 36 to the through hole 2 is formed in the guide rod 37. At the same time, a check valve portion 4 is formed at a portion above the junction of the through hole 2 and the elongated hole 3 to allow only upward gas flow.

The check valve portion 4 is formed at an upper portion of the through hole 2 and has a space portion 4A having a larger cross section than the lower portion, and is movably located in the space portion 4A. Has a cross section larger than that of the portion of the through-hole 2 that follows below, and is provided above the space 4A to close the portion of the through-hole 2 when descending. And a regulating member 4C which does not hinder the flow of the air. For example, the valve body 4B is a sphere, at least the inner wall surface of the space 4A is formed of a member having low sliding friction such as fluorocarbon resin, and the opening from the through hole 2 to the space 4A is formed in a funnel shape. The member may be a metal net or a plate formed with a large number of holes.

The intake control valve 1 having such a configuration
Then, when the valve element 21 is operated toward the valve seat 22, the gas in the recess 36 flows out of the upper and lower openings of the through hole 2 without being obstructed by the check valve portion 4. Can respond immediately. On the other hand, when the valve body 21 operates in the reverse direction, the flow of gas from the check valve portion 4 into the recess 36 is prevented, that is, the gas flows from the lower opening of the through hole 2. Because it is limited only to gas inflow,
It can no longer work sharply.

Therefore, for example, as described above, when the amount of used air is reduced and the compressor body is automatically stopped or manually stopped, the valve body 21 is operated as a check valve. First, the valve body 21 is immediately seated on the valve seat 22 to eliminate the backflow of the discharge gas and the lubricating oil due to the delay in closing, thereby preventing the peripheral portion of the compressor body from being contaminated by the lubricating oil. it can. In addition, since the one-way operation of the valve body 21 is restricted, generation of abnormal noise due to operation of the valve body 21 due to slight load fluctuation on the discharge side or vibration of the compressor is suppressed. Further, as a result of immediately closing the suction passage 13 as described above, the backflow of the compressed gas and the lubricating oil is eliminated, and the peripheral portion of the compressor is prevented from being contaminated with the lubricating oil. In order to appropriately adjust the flow rate of gas from the lower part of the through hole 2, a throttle may be provided at the lower part.

The check valve portion 4 in the present invention is not limited to the above-described structure, but may have any structure that can function as a check valve.
3 shows an example of another structure. In the check valve portion 4, a regulating member 4C having a cross-shaped opening 4D is used.
In FIGS. 3 and 4, parts common to FIGS. 1 and 2 are denoted by the same reference numerals.

[0021]

As is apparent from the above description, according to the present invention, in the intake control valve of the screw compressor, the vertical penetration of the guide rod located outside the recess at the center of the valve body. A hole and a long hole for connecting the bottom of the recess to the through hole are formed in the guide rod, and a gas flow flowing upward to a portion above a junction of the through hole and the long hole. A check valve portion that allows only a check valve is formed.

For this reason, even when the valve body is suddenly operated to close the suction passage, the valve body is operated immediately, and the suction passage is closed without hunting.
It does not generate abnormal noise, prevents backflow of compressed gas and lubricating oil, prevents contamination of the surroundings of the compressor due to backflow of lubricating oil, and causes slight load fluctuations on the discharge side and vibration of the compressor. The operation of the valve body is also suppressed by
This has the effect of reducing the occurrence of hunting and abnormal noise.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an intake air control valve of an oil-cooled compressor according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a plan view showing another embodiment of the check valve part in the intake air control valve of the oil-cooled compressor according to the present invention.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 4;

FIG. 5 is a cross-sectional view of an intake control valve of a conventional oil-cooled compressor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 intake control valve 2 through hole 3 long hole 4 check valve 4A space 4B valve 4C regulating member 21 valve 22 valve seat 23 upstream suction space 24 downstream suction space 36 recess 37 guide dedicated 38 piston rod

Claims (1)

[Claims] 1. An annular suction passage comprising an upstream suction space and a downstream suction space following the upstream suction space, wherein a valve seat is formed at an end of the upstream suction space on the downstream suction space side. A protrusion is provided, and a guide is protruded from the upstream suction space toward the downstream suction space at the center of the valve seat and perpendicular to the surface of the valve seat. A valve body cooperating with the valve seat in the downstream suction space is movably provided along the guide member which is relatively slidably fitted into a recess at the center thereof. When the piston rod to be operated is protruded into the downstream suction space so as to be movable in parallel with the axis of the guide, and the top of the valve body contacts the end of the piston rod, the valve is used. Spring means for biasing the body in the direction toward the valve seat are provided. In the intake control valve of the screw compressor has a longitudinal through hole in the portion of the guide rod outside the recess,
The guide rod is provided with a long hole for connecting the bottom of the recess to the through hole, and only a gas flow upward to a portion above a junction of the through hole and the long hole is allowed. An intake control valve for a screw compressor, wherein a check valve portion is formed.