JPH0231595Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a lubricating oil supply device for a screw compressor.

(Prior Art and its Problems) A screw compressor compresses intake gas by having male and female rotors formed with a pair of helical lands meshing with each other and rotating in a casing.

At the same time, lubricating oil is supplied into the compressor to lubricate, seal, and cool the compression space and lubricate sliding parts such as bearings and shaft seals.

As this type of screw compressor, the special public
A screw compressor disclosed in Japanese Patent No. 44541 is known.

As shown in FIG. 4, this compressor is provided with an unloader device 3 for controlling the amount of intake air above the suction chamber 42 of the casing 2, and a shaft sealing device 66 such as a mechanical seal or an oil seal in the shaft sealing chamber 14.
is installed to maintain a seal with the outside.

Furthermore, the discharge chamber 7 includes a check valve 8 and a gas port 9 that communicates with the pressurized air tank/liquid tank 4 via the discharge pipe 43.
and a liquid pump 11 and a passage 2 from the bottom wall of the discharge chamber.
Liquid reservoir 12 provided in the pressure air tank and liquid tank via 8
A liquid drain port 10 communicating with is provided.

Then, the liquid reservoir 12 is supplied to the working space 13 after the suction of the compressor is closed, the suction side shaft sealing chamber 14, and the discharge side shaft sealing mechanism 15 through the oil cooler 22, oil pump 23, and oil amount adjustment valve 25, respectively. A lubricating oil supply circuit that supplies lubricating oil in parallel, three-way solenoid valves SV ₁ and SV ₂ and unloader device 3 when starting the compressor.
and a starting load reduction device that reduces the starting torque of the compressor in cooperation with the compressor.

In its operation, first the compressor is started by a driving motor (not shown), and the compressor is started in the pressure air tank/liquid tank 4.
When the internal pressure reaches a certain pressure (1 to 2 Kgf/cm ² gauge pressure), the starting load reducing device is activated, and the unloader device 3 cuts off the intake air flowing into the compressor, and at the same time the oil amount adjustment described above is performed. valve 2
5 operates to throttle the amount of lubricating oil supplied to the compressor and limit the supply of more than necessary.

As a result, the pressure in the discharge chamber 7 drops to approximately 0 kgf/cm ² gauge pressure, the back pressure applied to the discharge port of the screw rotor is removed, the compressor enters a completely no-load operating state, and its operating power decreases. .

That is, during the above operation, the drive motor operates in a reduced voltage state, and after the pressure in the discharge chamber 7 reliably drops to about 0 Kgf/cm ² gauge pressure, it shifts to full voltage operation and returns to normal operation. Transition.

In the conventional compressor as described above, the lubricating oil supply system to the compressor passes through the oil amount adjustment valve 25 and then flows into the working space 13, the shaft sealing chamber 14 on the suction side, and the shaft sealing mechanism 15 on the discharge side. Since they were supplied in parallel, the following problems arose.

(a) During no-load operation of the compressor, the intake blockage valve 5 is closed by the unloader device 3, and the amount of lubricating oil supplied to the compressor is further restricted by the oil amount adjustment valve 25. , the pressure within the suction side shaft sealing chamber 14 communicating with the suction chamber 42 of the compressor via the passage 38 becomes negative pressure, and a shaft sealing portion (not shown) of the shaft sealing device 66 enters the shaft sealing chamber. air is easily inhaled.

Therefore, in shaft seal devices such as mechanical seals in which the shaft seal part has a sliding structure, surface roughness or seizure is likely to occur due to poor lubrication in the part of the sliding part near the atmosphere side. In such a case, not only will the deterioration of the shaft sealing function be accelerated, but also the air sucked in from the outside will flow through the passage 38 into the suction chamber 4.
2, the back pressure in the discharge chamber 7 cannot be removed, and the pressure in the pressure gas tank/liquid tank 4 increases, resulting in a problem of increased power consumption during no-load operation.

Furthermore, if the shaft sealing device is to be able to withstand the negative pressure within the shaft sealing chamber 14, a shaft sealing device that is much more expensive and has a complicated structure must be used.

(b) On the other hand, since the oil supply to the discharge side shaft sealing mechanism 15 is parallel to the suction side bearing chamber and the working space, most of the lubricating oil is supplied to the shaft sealing chamber 14 due to the negative pressure inside the shaft sealing chamber 14. When the viscosity of the lubricating oil becomes high, especially in cold weather, or when the operation is stopped for a long period of time, there will be insufficient lubrication to the shaft sealing mechanism on the discharge side, and the rotor Seizure occurred between the discharge side end face 17 of the casing 16 and the end face of the casing 18 .

(c) Also, as mentioned above, since the inside of the shaft sealing chamber 14 and the inside of the suction chamber 42 are in communication via the passage 38,
Particularly during repeated full-load operation and no-load operation, pressure fluctuations within the shaft sealing chamber are large, and the shaft sealing device 6
The shaft sealing action of No. 6 tends to become even more unstable, and there is a risk that lubricating oil may leak from the shaft sealing portion to the outside.

(Purpose and Means of the Invention) Therefore, the present invention maintains the pressure inside the shaft sealing chamber 14 at a positive predetermined pressure or higher at all times regardless of whether the compressor is in no-load operation or full-load operation, and the shaft sealing device 66 The purpose is to stabilize the sealing effect, eliminate the lack of oil supply to the discharge side shaft sealing mechanism 15 that occurs when the compressor is started, and prevent seizing accidents on the discharge side end face of the rotor. In the lubricating oil supply circuit connected to each of the suction side shaft sealing chamber and the discharge side shaft sealing mechanism, an amount of lubricating oil is supplied to the compressor in conjunction with the closing operation of the intake blockage valve during no-load operation of the compressor. The discharge chamber of the compressor has a gas port that communicates with the pressure air tank and liquid tank via a check valve, and a gas port that is at a lower level than the gas port. A liquid extraction port is provided at the position, and the compressed gas in the mixed fluid of compressed air and lubricating oil discharged from the discharge port during operation is transferred from the gas port to the pressurized air tank and liquid tank, and the lubricating oil is transferred to the liquid tank from the liquid removal port. In a screw compressor configured to pressurize liquid into the respective reservoirs via a extraction pump, a throttling mechanism is provided between the shaft sealing space of the suction side shaft sealing chamber and the suction side end wall, and the oil amount is adjusted. It is characterized in that the primary side oil passage of the valve is connected to the suction side shaft sealing chamber of the compressor, and the secondary side oil passage of the regulating valve is connected to the working space and the discharge side shaft sealing mechanism, respectively.

(Function) Since the present invention has the above-described configuration, negative pressure does not occur in the suction side shaft sealing chamber during no-load operation of the compressor, and furthermore, even when full-load operation and no-load operation are rapidly repeated. Since pressure fluctuations within the shaft sealing chamber can be made minute and always maintained at a positive predetermined level or higher, stable operation of the shaft sealing device can be achieved.

Furthermore, the lack of lubricant supply to the discharge-side shaft sealing mechanism that occurs when the compressor is started can also be resolved.

(Example) The same parts as in FIG. 4 will be described below using the same symbols.

FIG. 1 shows an embodiment of the screw compressor according to the present invention, in which an unloader device 3 is arranged above the casing 2, and the amount of compressed air on the consumption side supplied from the pressure air tank/liquid tank 4 is controlled. In response, the intake blockage valve 5 is opened and closed to control the amount of intake air into the compressor 1.

At the same time, when the compressor is started, the intake blocking valve is closed by a combined operation of the electromagnetic valves SV ₁ and SV ₂ communicating with the pressure air tank/liquid tank, thereby creating a starting load that reduces excessive starting torque of the compressor. It also functions as a mitigation device.

Further, the discharge port 6 is provided with a discharge chamber 7, and the discharge chamber has a gas port 9 that communicates with the pressure air tank/liquid tank 4 via a check valve 8, and an opening at a lower level position than the gas port. A mixed fluid of compressed air and lubricating oil injected into the compression chamber, which will be described later, is separated in this discharge chamber 7 due to a difference in specific gravity.
Gas is forced into the pressure gas tank/liquid tank 4 from the gas port 9 via the discharge pipe 43.

On the other hand, the lubricating oil that has flowed down to the bottom wall of the discharge chamber 7 is constantly transferred to the liquid reservoir 12 of the pressure tank/liquid tank 4 through the liquid drain port 10 and the liquid drain pump 11 regardless of whether the operation is under full load or no load. It will be collected.

The lubricating oil stored in the liquid reservoir 12 is pushed out by the compressed air pressure in the pressure air tank, and the lubricating oil is
1, oil cooler 22, oil passage 24, oil amount adjustment valve 25
The oil is injected from the oil passage 26 into the working space 13 to lubricate, seal, and cool the compression chamber, and is also branched from the oil passage 26 and supplied in parallel to the discharge side shaft sealing mechanism. and lubricates the end face of the casing 18 and the bearing 19.

On the other hand, lubricating oil is directly supplied into the shaft sealing chamber 14 on the suction side through an oil passage 27 branched from the oil passage 24, which is the primary oil passage of the oil amount adjustment valve.

A bearing 6 that supports the rotor 16 is provided in the bearing chamber 14.
5 and a shaft sealing device 66 are disposed, each of which forms a bearing space 69 and a shaft sealing space 70 via a throttle mechanism 68 fitted to the base of the rotor shaft 67.

There is a slight gap between the outer periphery of the throttle mechanism 68 and the suction side end wall 71 of the casing 2, which communicates with the shaft sealing chamber 14 and the suction chamber 42, and the lubricating oil supplied into the shaft sealing chamber is passed through the throttle. The mechanism 68 collects the oil into the suction chamber 42 through the suction side end wall 71 while maintaining the inside of the shaft sealed chamber at a constant positive predetermined pressure or higher (approximately 1 to 2 Kgf/cm ² gauge pressure).

The oil amount adjustment valve 25 is connected to the body 5 as shown in FIG.
It is composed of a piston 52 that can freely slide inside the compressor 1, and a spring 53 that biases the sliding movement of the piston. At the same time, passage 36
Piston 52 due to compressed air pressure supplied from
moves to the left in the figure, the seat portion 54 closes the primary oil passage 24 and the secondary oil passage 26, and a throttle passage 55 formed in the piston 52 restricts both passages to a constant oil amount. be done.

Further, when the supply of compressed air from the passage 36 is stopped, the piston 52 moves to the right in the figure due to the bias of the spring 53, and the primary oil passage 24 and the secondary oil passage 26 are fully opened.

In this way, the purpose of limiting the supply amount of lubricating oil by the oil amount adjustment valve 25 during no-load operation of the compressor is to
During no-load operation of the compressor, the air is not compressed in the working space 13, so no heat is generated, so a very small amount of lubricating oil for lubrication and sealing is supplied. This is because the amount of lubricating oil is sufficient, and thereby the power consumption due to excessive supply of lubricating oil is also reduced.

Further, the size of the throttle passage 55 is appropriately selected depending on the type of compressor.

FIG. 3 shows a second embodiment of the present invention, which is a detailed view of the main part of the shaft sealing chamber 14 on the suction side.

Suction side end wall 71 of casing 2 and rotor shaft 67
There is a suction chamber 42 and a bearing space 69 between the base outer periphery of the
A passage 38 is provided to communicate with the bearing space 69 and the shaft sealing space 70, and a throttle mechanism 75 is provided via a bearing 65 between the bearing space 69 and the shaft sealing space 70.

The throttle mechanism 75 is fitted into and fixed to the casing 2 with a slight gap between the outer periphery of the rotor shaft 67 and the outer periphery of the rotor shaft 67 .

Therefore, the lubricating oil supplied into the shaft sealing chamber 14 lubricates the bearing 65 through the gap, and then flows into the suction chamber 42 through the bearing space 69 passage 38.

The embodiment of the present invention is as described above, and the operation will be explained next.

First, when the switch of the starter (not shown) is turned on, a timer is activated and the three-way solenoid valve SV ₁ is de-energized, and the circuit 31 communicating with the pressure tank/liquid reservoir 4 is turned on.
and circuit 32 is open, circuit 32 and circuit 35 are closed, and at the same time three-way solenoid valve SV ₂ is de-energized, circuit 31 and circuit 33 via pressure reducing valve 30 are closed, circuit 33 and circuit 3
4 is open.

In this state, suction air flows into the suction chamber 42 from the suction port 41 of the unloader device, is compressed in the working space 13, passes through the discharge chamber 7 and the discharge pipe 43, and is accumulated in the pressure tank/liquid tank 4.

Then, the pressure in the pressure tank is a minimum pressure (1 to
2Kgf/cm ² gauge pressure), the compressed air pressure from the circuit 31 causes the unloader piston 44 to
is slid to the left in the figure, the intake blockage valve 5 is closed, the compressor 1 is placed in an unloaded state, and the suction chamber 42 becomes under negative pressure.

At the same time, since the circuits 32 and 36 are in communication, the oil amount adjustment valve 25 also closes the piston 52, throttles the oil passages 24 and 26, and reduces the amount of lubricating oil supplied to the working space 13 and the discharge side shaft sealing mechanism 15. reduce

On the other hand, since the lubricating oil branched from the primary oil passage 24 of the oil volume adjustment valve 25 is directly introduced into the shaft sealing chamber 14 on the suction side, the lubricating oil is constantly supplied at a fixed amount regardless of the closing operation of the oil volume adjustment valve. lubricating oil is supplied, and the amount of oil supplied to the working space 13 and the discharge side shaft sealing mechanism 15 is also maintained at a fixed amount without being affected by the negative pressure in the suction chamber 42.

Furthermore, the lubricating oil that has flowed into the shaft sealing chamber 14 is transferred to the shaft sealing device 66 and the bearing 6 while maintaining the internal pressure in the shaft sealing chamber at a positive predetermined pressure or higher through the intervention of the throttle mechanism 68.
5 is lubricated and then collected into the suction chamber 42 from the suction side end wall 71 via the throttle mechanism.

Then, the working space is lubricated together with a small amount of lubricating oil injected into the working space 13, and the discharge port 6
more excreted.

Then, the lubricating oil flows down to the bottom wall of the discharge chamber 7, and is forced into the liquid reservoir 12 through the liquid extraction port 10 by the liquid extraction pump 11 together with the remaining compressed gas.

Then, the residual gas in the discharge chamber is diffused, and the pressure is reduced to about 0 kgf/cm ² gauge pressure.

As a result, the back pressure applied to the discharge port 6 of the screw rotor is removed, so that the compressor starts with the load greatly reduced.

After the above operations, the compressor shifts to steady operation.

Thereafter, the three-way solenoid valves SV ₁ and SV ₂ are energized by the operation of a timer (not shown), circuits 31 and 32 are closed, and circuits 36 and 32 are replaced by circuit 3.
5 and 34, the circuit 31 and the circuit 33 are in communication, and the circuit 33 and the circuit 34 are closed, and the unloader piston 44 moves to the right in the figure, and the intake block valve 5 opens to perform compression. The machine transitions to full load operation.

Furthermore, when the pressure in the pressure air tank/liquid storage tank reaches the specified pressure, the pressure switch PS ₁ is activated and the state shifts to no-load operation under steady-state operation, resulting in air intake blockage and oil supply restriction as described above. , performs operations such as removing residual pressure in the discharge chamber, and greatly reduces power consumption during no-load operation.

After that, similar repeated operations are performed.

Further, in the second embodiment shown in FIG. 3, a throttle mechanism 75 is provided between the shaft seal space 70 and the bearing space 69, and the bearing 65 is disposed on the bearing space side.
The lubricating oil supplied into the shaft sealing chamber 14 is passed through the throttle mechanism 75.
While maintaining the pressure in the shaft sealing space 70 above a predetermined positive pressure, the shaft sealing device 66 is lubricated, and the bearing 65 is lubricated through a small gap between the throttle mechanism and the rotor shaft 67.

That is, since the inside of the bearing space 69 is supplied with a small amount of lubricating oil squeezed by the throttle mechanism 75, the inside of the shaft sealing chamber 14 is filled as in the structure of the first embodiment shown in FIG. This eliminates the need to raise the temperature of the lubricating oil due to the stirring action of the bearing 65, and the durability of the bearing and shaft sealing device 66 is improved, making it particularly suitable for high-speed rotation compressors.

(Effects of the invention) With the above configuration, the present invention operates when the compressor starts up, the startup load reduction device operates, the intake blockage valve closes, and the oil amount adjustment valve limits the amount of oil supplied to the compressor. Even at the time when the shaft is sealed, the inside of the shaft sealing chamber on the suction side is always maintained at a predetermined pressure or higher by the action of the throttle mechanism, so that a stable shaft sealing function can always be maintained without using an expensive shaft sealing device.

In addition, even during no-load operation, there is no air inflow from the shaft seal part of the suction side shaft seal device, and the problem of lubricating oil leaking from the shaft seal part is also eliminated, and the leakage of lubricating oil in the pressure air tank and liquid tank is also eliminated. There will be no pressure increase.

In addition, the oil supply to the shaft seal chamber is separated from the oil supply passage to the working space and the discharge side shaft seal mechanism, and is introduced directly from the primary oil passage of the oil amount adjustment valve. The lack of oil supply to the discharge side shaft sealing mechanism that had occurred in the previous example was resolved, and seizure of the discharge side end face of the rotor and casing could not be prevented.

[Brief explanation of the drawing]

FIG. 1 is an overall view of the compressor according to the present invention, and FIG. 2 is an enlarged cross-sectional view of the oil amount regulating valve. FIG. 3 is a detailed view of the main parts of the shaft sealing chamber of the second embodiment, and FIG. 4 is an overall view of a conventional compressor. 1... Compressor, 3... Unloader device, 4...
Pressure air tank/liquid tank, 5...Intake blockage valve, 6...Discharge port, 7...Discharge chamber, 8...Check valve, 9...Gas port, 10...Liquid outlet, 11...Liquid Bleeding pump, 12...Liquid reservoir, 13...Working space, 15...
... Shaft sealing mechanism, 14 ... Shaft sealing chamber, 25 ... Oil amount adjustment valve, 24 ... Oil passage (primary side), 65 ... Bearing,
66... Shaft sealing device, 68... Throttle mechanism, 69...
Bearing space, 70... Shaft seal space, 75... Throttle mechanism.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) An intake blockage valve during no-load operation of the compressor is installed in the lubricating oil supply circuit connected to the working space of the compressor, the suction side shaft sealing chamber, and the discharge side shaft sealing mechanism. It has an oil amount adjustment valve that limits the amount of lubricating oil supplied to the compressor to less than that during full-load operation in conjunction with the closing operation of the compressor, and pressurized air is supplied to the discharge chamber of the compressor via a check valve. A gas port communicating with the tank/liquid tank and a liquid outlet located at a lower level than the gas port are provided, and the compressed gas in the mixed fluid of compressed air and lubricating oil discharged from the discharge port during operation is discharged from the gas port. In a screw compressor configured so that the lubricating oil is pressurized into the liquid reservoir from the liquid extraction port via the liquid extraction pump, the lubricating oil is transferred to the shaft sealing space of the suction side shaft sealing chamber and to the pressure air tank and liquid tank. A throttling mechanism is provided between the suction side end walls, and the primary oil passage of the oil amount adjustment valve is connected to the suction side shaft sealed chamber of the compressor, and the secondary oil passage of the adjustment valve is connected to the working space and the discharge side shaft. An oil supply device for a screw compressor, characterized in that it is connected to a sealing mechanism. (2) The oil supply device for a screw compressor according to claim 1, wherein the throttle mechanism is provided between a suction side bearing space and a suction side end wall of the compressor. (3) The oil supply device for a screw compressor according to claim 1, wherein the throttle mechanism is provided between a suction side bearing space and a shaft sealing space of the compressor.