WO2023153081A1

WO2023153081A1 - Oil-free air compressor

Info

Publication number: WO2023153081A1
Application number: PCT/JP2022/046606
Authority: WO
Inventors: 佑貴石塚; 雄二伊藤
Original assignee: 株式会社日立産機システム
Priority date: 2022-02-09
Filing date: 2022-12-19
Publication date: 2023-08-17
Also published as: JP2023116366A

Abstract

Provided is an oil-free air compressor that prevents reverse rotation of a compressor body while the compressor is out of service, thereby preventing oil from entering the compressor body, and improving the reliability, as well as exhibiting a rust preventive effect. An oil-free air compressor 100 comprising: an oil-free compressor body 1 that compresses air and outputs the compressed air; a cooler 5 that is connected to the compressor body, and cools the compressed high-temperature air; a dry air supply mechanism that supplies dry air to an output side of the compressor body; and a mechanism that prevents reverse rotation of the compressor body while the compressor is out of service.

Description

Oil-free air compressor

The present invention relates to an oil-free air compressor such as an oil-free screw compressor.

There are oil-free and oil-lubricated air compressors. The oil-free screw compressor does not use lubricating oil or has a structure in which lubricating oil does not enter the compression chamber, so clean compressed air containing no oil is obtained, and the rotor rotates without contact. Therefore, it has the advantage of being durable and time-saving.

In addition, in air compressors, the moisture contained in the compressed air may cause rusting when operation is stopped, and it is necessary to prevent rusting.

In response to this problem, Patent Document 1 discloses a method for preventing rust of a compressor during outage, which is described as follows. A rust-preventing method for a compressor during stoppage of operation, characterized in that the moisture-containing gas sucked into the compressor and remaining in the compressor is replaced with dry gas.” (see claim 1). ing.

JP-A-5-141350

Patent Document 1 discloses a technique of sucking dry gas into the compressor when the operation is stopped and replacing the gas containing moisture remaining in the compressor with the dry gas as a method for preventing rust of the compressor when the operation is stopped. It is

The position to supply the dry gas is preferably the discharge side of the compressor body and the downstream side of the cooler. This is because the air compressed by the main body of the compressor becomes moist air when cooled by the cooler, and direct replacement of the moist air with dry gas is highly effective.

The compressor body has an internal gap of several tens of μm to prevent air leakage during compression. If the male and female rotors do not rotate, air must pass through this minute gap to flow from the intake port of the compressor body to the discharge port. Therefore, even if dry gas is supplied to the suction side, it is difficult for it to flow to the discharge side, and it is not suitable for the purpose of replacing wet air with dry gas.

On the other hand, when air is introduced from the outside into the discharge side of the compressor body, if a large amount of dry air is introduced in order to significantly increase the anti-corrosion effect, a force will act to rotate the compressor body in the opposite direction. When the compressor main body rotates in the reverse direction, the lubricating oil acts to be pulled in from the bearing toward the working chamber. If the working chamber is mixed with lubricating oil, the advantage of the oilless compressor of obtaining clean compressed air containing no oil is lost.

The present invention is an oil-free air compressor that improves reliability by preventing oil from entering the compressor body by preventing reverse rotation of the compressor body when the compressor is out of operation, while increasing the rust prevention effect. intended to provide

To give an example of the "oil-free air compressor" of the present invention for solving the above problems,
An oil-free air compressor comprising: an oil-free compressor body for compressing and outputting air; and a cooler connected to the compressor body for cooling the compressed high-temperature air, wherein the compressor It is provided with a dry air supply mechanism for supplying dry air to the output side of the main body and a mechanism for preventing reverse rotation of the compressor main body while the compressor is out of operation.

Also, if another example of the "oil-free air compressor" of the present invention is given,
An oil-free low-pressure stage compressor body and a high-pressure stage compressor body that compress and output air, and an intermediate-stage piping that connects the low-pressure stage compressor body and the high-pressure stage compressor body , an intercooler provided in the intermediate stage for cooling the compressed high-temperature air, and an aftercooler provided on the output side of the high-pressure stage compressor main body, wherein the intermediate stage is and a mechanism for preventing reverse rotation of the main body of the low-pressure stage side compressor while the compressor is out of operation.

According to the present invention, while increasing the rust prevention effect, the reverse rotation of the compressor body is prevented when the compressor is out of operation, thereby preventing oil from entering the compressor body and improving reliability. A compressor can be provided.

Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing an oil-free screw compressor of Example 1 of the present invention; Fig. 2 is a diagram showing an oil-free screw compressor of Example 2 of the present invention; FIG. 3 is a diagram showing an oil-free screw compressor according to Example 3 of the present invention; FIG. 4 is a schematic internal structural diagram showing a state during operation of the trochoid pump; FIG. 4 is a schematic internal structural diagram showing a state when the trochoid pump is closed; FIG. 4 is a diagram showing an oilless screw compressor according to Embodiment 4 of the present invention; FIG. 5 is a diagram showing an oil-free screw compressor according to Embodiment 5 of the present invention; FIG. 6 is a diagram showing an oil-free screw compressor of Example 6 of the present invention. Fig. 2 is a cross-sectional plan view showing the internal structure of the compressor body of the oilless screw compressor. FIG. 2 is a front cross-sectional view showing the internal structure of the compressor body of the oilless screw compressor.

Before describing embodiments of the present invention, an oil-free screw compressor, which is an example of an oil-free air compressor, will be described.

　Figures 8A and 8B show cross-sectional views of the compressor body 1 of the oil-free screw compressor. 8A is a plan sectional view, and FIG. 8B is a front sectional view. The compressor main body 1 is a capacity control type air compressor in which the teeth of a pair of screw rotors consisting of a male rotor 50A and a female rotor 50B mesh with each other while maintaining a predetermined gap and rotate at high speed to generate compressed air. machine.

The male rotor 50A is integrally or directly connected to the rotor shaft 48A, and the female rotor 50B is connected to the rotor shaft 48B.

Bearings

11A and 11B are arranged on the rotor shafts of the male rotor 50A and the female rotor 50B, respectively, in the air suction side end direction, and

bearings

12A, 12B are arranged in the air discharge side end direction. Supported. Further,

timing gears

9A and 9B are arranged at the outer ends of the

rotor shafts

48A and 48B, respectively, beyond the

bearings

12A and 12B. The engagement of 9A and 9B allows the male and female rotors to rotate relative to each other. As the male and female rotors rotate, the air sucked from the intake port 41 is compressed in the working chamber 60, and is eventually supplied from the discharge port 42 through a predetermined compressed air path to the user side.

On the suction side of

rotor shafts

48A and 48B, shaft seal portions 17 (17A and 17B) and shaft seal portions 18 (18A and 18B) are provided between male and

female rotors

50A and 50B and

bearings

11A and 11B. are placed. The shaft seal portion 18 is an air seal, and is an annular member for reducing leakage of the air compressed in the working chamber 60 to the side of the bearing 11A and the like. The shaft seal portion 18 is not in contact with the rotor shaft 48A and the like, and the gap therebetween is as small as several tens of micrometers. Air seals 18A (male side) and 18B (female side) are arranged on the rotor shafts 48 of the male and

female rotors

50A and 50B, respectively.

The shaft seal portion 17 is a screw seal and serves to prevent the lubricating oil supplied to the

bearings

11A and 11B via the path 34 from entering the working chamber 60. As shown in FIG. The

screw seals

17A and 17B have helical square grooves on their inner surfaces, and are assembled so as to maintain a minute gap without contact with the rotor shaft 48A or the like. The

screw seals

17A and 17B generate seal pressure in the grooves of the inner diameter portion due to the rotation of the rotor shaft 48A and the like, thereby pushing the lubricating oil back toward the

bearings

11A and 11B.
A groove is formed in the circumferential direction between the shaft seal portions 17 and 18 of the rotor shaft 48A and the like. 43 is formed. The hole portion 43 functions as a gas vent hole or the like for releasing leaked air from the working chamber 60 to the outside of the compressor body 1 .
Further, an oil drain port 45 is formed between the

screw seals

17A, 17B and the

bearings

11A, 11B to collect lubricating oil lubricating the

bearings

11A, 11B and return it to the oil reservoir 47 of the gear casing 2. .

Similar to the configuration of the suction sides of the

rotor shafts

48A and 48B, the shaft seal portions 20 (air seals) and the shaft seal portions 19 (screw seals) are arranged on the discharge sides of the

rotor shafts

48A and 48B. A shaft seal portion 19 and a shaft seal portion 20 are arranged between the

rotors

50A, 50B and the

bearings

12A, 12B. A hole portion 44 is formed between the shaft seal portion 19 and the shaft seal portion 20 of the compressor body casing, communicating with the outside air and functioning as a vent for compressed air leaking from the working chamber 60 .

Three

bearings

12A and 12B are arranged on each of the male and female rotor shafts. A path 33 for supplying lubricating oil from above is formed at any position between these three bearings 12 in the compressor body casing. Further, the compressor body casing is formed with a discharge port 46 for recovering lubricating oil from a position between the

bearings

12A, 12B and the

screw seals

19A, 19B. The lubricating oil supplied from the path 33 lubricates the

bearings

12A and 12B, and then is recovered from the oil drain port 46. As shown in FIG.

The compressor body casing is formed with a path 35 for supplying lubricating oil above the timing gears 9A and 9B. is recovered in the oil reservoir 47 from the The path 35 is formed to branch off from the path 33 on the compressor casing, and the oil drain port 46 is formed to merge with the oil drain port 45 in the middle.

The shaft seal 17 (screw seal) pushes the lubricating oil back toward the

bearings

11A and 11B when the compressor body rotates forward, but draws the lubricating oil from the bearings toward the working chamber when the compressor body rotates in the reverse direction. Therefore, it is not preferable for the compressor body to rotate in the opposite direction.

In such an oil-free air compressor, the present invention prevents oil from entering the compressor body by preventing reverse rotation of the compressor body when the compressor is out of operation, while increasing the rust prevention effect. It improves reliability.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention should not be construed as being limited to the contents of the examples described below. Those skilled in the art will easily understand that the specific configuration can be changed without departing from the idea or gist of the present invention.
In addition, in the configuration of the invention described below, the same reference numerals may be used in common for the same parts or parts having similar functions in different drawings, and redundant description may be omitted.

Fig. 1 shows an oil-free screw compressor according to Example 1 of the present invention. It should be noted that FIG. 1 shows a case in which the minimum necessary equipment is installed, and other equipment may be installed.

The compressor 100 includes a compressor body 1, a gear casing 2, a motor 3a as a drive source for the compressor body 1, and a motor 3c as a drive source for the oil pump . A speed-increasing drive gear 6 is attached to the output shaft of the motor 3a arranged on the side surface of the gear casing 2. As shown in FIG. The speed-increasing driving gear 6 meshes with a speed-increasing driven gear 7 set to a predetermined gear ratio, and applies a driving force to the male rotor of the compressor body 1 through a rotor shaft connected to the speed-increasing driven gear 7. introduce.

The oil pump 24 is attached to the side surface of the gear casing 2 with a flange connection, and supplies driving force via an oil pump driven gear 8B that meshes with an oil pump driving gear 8A attached to the motor 3c at a predetermined gear ratio. transmitted.
The oil pump 24 is a pump that circulates lubricating oil to various driving parts of the compressor 100, and circulates lubricating oil to various oil paths arranged in the compressor 100 by driving force transmitted through the oil pump shaft. to pump. The oil pump 24 sucks the lubricating oil from the oil reservoir 47 provided in the lower part of the gear casing 2 through the on-off valve 15, and pumps it through the path 14 to an oil cooler (not shown). . The oil cooler is an air-cooled or water-cooled heat exchanger using a fan (not shown), and cools the lubricating oil to a predetermined temperature or less.

The air that has been compressed by the compressor body 1 and has a high temperature becomes moist air when cooled by the aftercooler 5. Therefore, replacing it with dry air is effective for rust prevention.

In this embodiment, a dry air supply line 23 having a dry air supply port 21 and a supply valve 22 is provided on the downstream side of the aftercooler 5, and dry air stored in an air tank 28 is supplied thereto. The supply valve 22 is opened and closed at predetermined timing by the control panel 32 .

If high-pressure dry air is supplied to the discharge side of the compressor body 1 while the compressor is out of operation, the pressure on the discharge side of the compressor body 1 will increase, and the compressor body 1 may rotate in the reverse direction. Therefore, in this embodiment, a brake device 70 for the compressor main body 1 is provided, which operates when the operation is stopped.

The brake device 70 is connected to the male rotor of the compressor main body 1 and controlled by the control panel 32 so that the male rotor does not rotate while dry air is being supplied. By adopting this configuration, it is possible to prevent the compressor body 1 from rotating in the reverse direction while the dry air is being supplied.

The operation of the compressor is as follows.
During operation of the compressor, air is sucked into the compressor main body 1 from the air suction port 101 through the air suction pipe 103 . Compressed air that has been compressed in the compressor main body 1 and heated to a high temperature is cooled by the aftercooler 5 and is output from the compressed air discharge port 102 via the check valve 25 .
When the compressor is out of operation, the motor 3a stops and the compressor body 1 stops. Then, the air release valve 26A connected between the compressor main body 1 and the aftercooler 5 is opened to release the pressure inside the compressor. Then, the dry air stored in the air tank 28 is supplied from the dry air supply line 23 to the output side of the aftercooler 5 . The dry air supplied from the supply port 21 is discharged into the atmosphere from the air release valve 26A. At this time, the pressure on the discharge side of the compressor main body 1 rises due to the dry air supplied from the supply port 21, so that a force is applied to rotate the compressor main body 1 in the reverse direction. Since the brake is applied, reverse rotation of the compressor main body 1 is prevented even if high-pressure dry air is supplied.

The brake device is an example of a mechanism that prevents reverse rotation of the compressor body, and any device that can prevent reverse rotation of the compressor body may be used. Another example is a ratchet mechanism.

According to this embodiment, in a single-stage compressor, when the compressor is out of operation, high-pressure dry air is supplied to the piping on the output side of the aftercooler to increase the rust prevention effect, and to operate during the outage. Since the brake device for the compressor main body is provided, the reverse rotation of the compressor main body can be prevented. In addition, it is possible to provide an oil-free air compressor with improved reliability by preventing oil from entering the compressor body.

FIG. 2 shows an oil-free screw compressor of Example 2 of the present invention. Note that FIG. 2 shows a case where the minimum required equipment is installed, and other equipment may be installed.

The compressor 100 includes a low-pressure stage compressor body 1a, a high-pressure stage compressor body 1b, a gear casing 2, and

motors

3a and 3b as drive sources. The low-pressure stage side compressor main body 1a and the high-pressure stage side compressor main body 1b are attached near the upper side surface of the gear casing 2 by flange connection. Speed increasing drive gears 6A and 6B are attached to the output shafts of the

motors

3a and 3b arranged on the side surface of the gear casing 2, respectively. The speed-increasing drive gears 6A, 6B mesh with the speed-increasing driven

gears

7A, 7B set to a predetermined gear ratio, and are connected to the low-pressure stage side compressor via rotor shafts connected to the speed-increasing driven

gears

7A, 7B. A driving force is transmitted to the male rotor of the main body 1a and the male rotor of the high pressure stage compressor main body 1b.

An intercooler 4 is provided on the discharge side of the low-pressure stage compressor main body 1a to cool the air that has been compressed and heated to a high temperature. An intermediate stage pipe 13 is provided to connect the intercooler 4 and the high-pressure stage compressor main body 1b, and supplies the compressed air cooled by the intercooler 4 to the high-pressure stage compressor main body 1b.
An aftercooler 5 is provided on the discharge side of the high-pressure stage compressor main body 1b to cool the compressed air that has reached a high temperature and output it via a check valve 25. As shown in FIG.

Since the air compressed by the low-pressure stage side compressor main body 1a becomes moist air when cooled by the intercooler 4, it is effective for rust prevention to replace it with dry air when the compressor is out of operation. be. Therefore, a dry air supply line 23 having a dry air supply port 21 and a supply valve 22 is provided in the intermediate stage piping 13 between the intercooler 4 and the high pressure stage side compressor main body 1b, and an air tank 28 is connected to the dry air supply line 23. supply dry air stored in The supply valve 22 is opened and closed at predetermined timing by the control panel 32 .

If high-pressure dry air is supplied to the intermediate-stage pipe 13 while the compressor is out of operation, the pressure on the discharge side of the low-pressure stage-side compressor body 1a increases, and the low-pressure stage-side compressor body 1a may rotate in the reverse direction. be. Therefore, in this embodiment, a brake device 70 for the low-pressure stage compressor main body 1a is provided, which operates when the operation is stopped.
The brake device 70 is connected to the male rotor of the low-pressure stage compressor main body 1a, and is controlled by the control panel 32 so that the male rotor does not rotate while dry air is being supplied. With this configuration, it is possible to prevent the main body of the low-pressure stage compressor from rotating in the reverse direction during the supply of dry air.

The operation of the compressor is as follows.
During operation of the compressor, air is sucked from the air suction port 101 through the air suction pipe 103 into the low-pressure stage side compressor main body 1a. Compressed air that has been compressed in the low-pressure stage compressor main body 1a and heated to a high temperature is cooled by the intercooler 4 and supplied to the high-pressure stage compressor main body 1b. Compressed air that has been further compressed in the high-pressure stage compressor main body 1 b and heated to a high temperature is cooled by the aftercooler 5 and is output from the compressed air discharge port 102 via the check valve 25 .
When the compressor is out of operation, the

motors

3a and 3b are stopped, and the low-pressure stage compressor body 1a and the high-pressure stage compressor body 1b are stopped. Then, the release valve 26A connected between the low-pressure stage compressor main body 1a and the intercooler 4 and the release valve 26B connected between the high-pressure stage compressor main body 1b and the aftercooler 5 are opened. Release the pressure inside the compressor. Then, the dry air stored in the air tank 28 is supplied from the dry air supply line 23 having the dry air supply port 21 and the supply valve 22 to the piping 13 of the intermediate stage. The dry air supplied from the supply port 21 to the intermediate-stage pipe 13 is released into the atmosphere from the

air release valves

26A and 26B. Since the pressure rises, a force acts to reversely rotate the low-pressure stage side compressor main body 1a. At this time, since the low-pressure stage side compressor body 1a is braked by the brake mechanism 70, the low-pressure stage side compressor body 1a is prevented from rotating in the reverse direction even if high-pressure dry air is supplied.

According to this embodiment, when the compressor is out of operation, high-pressure dry air is supplied to the intermediate stage piping to increase the rust prevention effect, and a brake device for the low-pressure stage side compressor that operates when the operation is out of operation is provided. Therefore, reverse rotation of the compressor body can be prevented. Further, it is possible to provide a multi-stage oil-free air compressor with improved reliability by preventing oil from entering the compressor body.

　Fig. 3 shows an oil-free screw compressor according to Embodiment 3 of the present invention. In the second embodiment, motors are provided for the low-pressure stage compressor main body, the high-pressure stage compressor main body, and the oil pump that supplies the lubricating oil. be.

The compressor 100 includes a low-pressure stage compressor main body 1a, a high-pressure stage compressor main body 1b, a gear casing 2, and one motor 3 as a drive source. A speed increasing drive gear 6 and an oil pump drive gear 8A are attached to the output shaft of the motor 3 arranged on the side surface of the gear casing 2 . The speed-increasing driving gear 6 meshes with speed-increasing driven

gears

7A and 7B set to a predetermined gear ratio, and is connected to the male of the low-pressure stage side compressor main body 1a via a rotor shaft connected to the speed-increasing driven gear 7A. A driving force is transmitted to the rotor and to the male rotor of the high-pressure stage compressor main body 1b via a rotor shaft connected to the speed-increasing driven gear 7B.
Further, the pump drive gear 8A meshes with the oil pump driven gear 8B set to a predetermined gear ratio. The pump driven gear 8B is connected to an oil pump shaft passing through the outside of the gear casing 2 and transmits driving force to the oil pump 24. As shown in FIG.

In the compressor 100 of this embodiment, the opening/closing valve 15 is provided on the suction side of the oil pump 24, that is, between the oil reservoir 47 and the oil pump 24.

　Figures 4A and 4B show a trochoid pump used as an oil pump, with Figure 4A showing the operating state and Figure 4B showing the closed state.

In the trochoid pump, a working chamber formed by an inner rotor 51 and an outer rotor 52 expands and contracts from a suction port 53 to a discharge port 54, thereby pumping lubricating oil from a suction flow path 55 to a discharge flow path 56.

Here, when a force to reversely rotate the trochoid pump is applied, the working chamber expands and contracts from the discharge port 54 to the suction port 53, so the lubricating oil flows back from the discharge port 54 to the suction port 53. At this time, if the suction flow path 55 is blocked, the lubricating oil cannot be sent to the suction side, and the working space cannot be contracted, so that the pump is locked.

By controlling the on-off valve 15 so that it is open while the compressor 100 is in operation and closed while it is stopped, the suction side 55 of the oil pump 24 is filled with lubricating oil as shown in FIG. Reverse rotation of the oil pump 24 can be prevented. Since the oil pump 24 and the compressor

main bodies

1a, 1b are connected via the drive gear 6, if the oil pump 24 cannot rotate, the compressor

main bodies

1a, 1b cannot rotate either. Therefore, reverse rotation of the compressor main body can be prevented while the compressor is stopped.

Although a trochoid pump is mentioned as an example, any gear pump that transports fluid by meshing gear teeth can be used.

According to this embodiment, in a multi-stage compressor, a single motor drives the compressor bodies on the low-pressure stage side and the high-pressure stage side and the oil pump through gears, and the oil pump is connected to the oil pump suction side of the compressor. By providing an on-off valve that opens during operation and closes during rest, reverse rotation of the compressor body can be prevented when the compressor is out of operation. In addition, it is possible to provide an oil-free air compressor with improved reliability by preventing oil from entering the compressor body.

FIG. 5 shows an oil-free screw compressor according to Embodiment 4 of the present invention. Embodiment 3 is a multi-stage compressor comprising a low-pressure stage side compressor main body 1a and a high-pressure stage side compressor main body 1b, but this embodiment is a single-stage compressor composed of one compressor main body. .

The compressor 100 includes a compressor body 1, a gear casing 2, and a single motor 3 as a drive source. A speed increasing drive gear 6 and an oil pump drive gear 8A are attached to the output shaft of the motor 3 arranged on the side surface of the gear casing 2 . The speed-increasing driving gear 6 meshes with a speed-increasing driven gear 7 set to a predetermined gear ratio, and applies a driving force to the male rotor of the compressor body 1 through a rotor shaft connected to the speed-increasing driven gear 7. introduce. Further, the pump drive gear 8A meshes with the oil pump driven gear 8B set to a predetermined gear ratio. The pump driven gear 8B is connected to an oil pump shaft passing through the outside of the gear casing 2 and transmits driving force to the oil pump 24. As shown in FIG. An on-off valve 15 is provided on the suction side of the oil pump 24 , that is, on the oil pump suction path 14 between the oil reservoir 47 and the oil pump 24 .

As described in Embodiment 1, the air that has been compressed by the compressor body 1 and has a high temperature becomes moist air when cooled by the aftercooler 5 . Therefore, replacing it with dry air is effective for rust prevention.

In this embodiment, a supply line 23 having a dry air supply port 21 and a supply valve 22 is provided on the downstream side of the aftercooler 5, to which dry air stored in an air tank 28 is supplied. The supply valve 22 is opened and closed at predetermined timing by the control panel 32 .

When the compressor is out of operation, the check valve 25 in the oil pump suction path 14 is normally closed, so the supplied dry air passes through the air release valve 26A or the compressor main body 1 to the suction port 101. It goes out of the compressor, but at this time, a force acts to reversely rotate the compressor main body 1 .

In this embodiment, the compressor body 1 is connected to the oil pump 24 via the drive gears 6 and 8A. Rotation can be prevented.

According to this embodiment, in a single-stage compressor, a single motor drives the compressor body and the oil pump through a gear, and the suction side of the oil pump is open during operation of the compressor and stops. By providing an on-off valve that closes inside, it is possible to prevent reverse rotation of the compressor main body when the compressor is out of operation. In addition, it is possible to provide an oil-free air compressor with improved reliability by preventing oil from entering the compressor body.

FIG. 6 shows an oil-free screw compressor of Example 5 of the present invention. Since the basic configuration is the same as that of the third embodiment shown in FIG. 3, differences will be explained here. This embodiment is characterized in that a dry air supply port is also provided on the suction side of the low-pressure stage compressor.

In this embodiment, the suction pipe 103 is provided with a dry air supply port 21A, a supply valve 22, and a dry air supply line 23A having an orifice 33A. A dry air supply line 23B having a dry air supply port 21B, a supply valve 22, and an orifice 33B is provided in the intermediate stage.

Explain how it works.
During operation of the compressor, air is sucked from the air suction port 101 through the air suction pipe 103 into the low-pressure stage side compressor main body 1a. Compressed air that has been compressed in the low-pressure stage compressor main body 1a and heated to a high temperature is cooled by the intercooler 4 and supplied to the high-pressure stage compressor main body 1b. Compressed air that has been compressed in the high-pressure stage compressor main body 1 b and heated to a high temperature is cooled by the aftercooler 5 and is output from the compressed air discharge port 102 via the check valve 25 .
When the compressor is out of operation, an air release valve 26A connected between the low-pressure stage compressor body 1a and the inner cooler 4, and an air release valve 26A connected between the high-pressure stage compressor body 1b and the aftercooler 5 Valve 26B is opened to release the pressure inside the compressor. Thereafter, by controlling the control panel 32 to open the supply valve 22, the dry air stored in the air tank 28 is supplied into the compressor through the dry

air supply lines

23A and 23B. The dry air supplied from the supply port 21B to the intermediate-stage pipe 13 is released into the atmosphere from the

air release valves

26A and 26B. The dry air supplied from the supply port 21A is discharged from the suction port 101 into the atmosphere.

At this time, the dry air supplied from the supply port 21B increases the pressure of the intermediate stage pipe 13, so that a force is exerted to reversely rotate the low-pressure stage compressor body 1a, while the dry air supplied from the supply port 21A is The pressure in the suction pipe 103 is increased to generate a force to rotate the low-pressure stage compressor main body 1a forward. By setting the diameters of the

orifices

33A and 33B in advance so that the force for forward rotation and the force for reverse rotation of the low-pressure stage side compressor main body 1a are balanced, the force for rotating the compressor in the forward direction and the force for rotating the compressor in the reverse direction cancel each other out. Therefore, reverse rotation of the compressor can be prevented.

In this embodiment, a multi-stage compressor has been described as an example, but the single-stage compressor shown in FIG. 1 can also be used. In that case, dry air is supplied by connecting the dry air supply port 21 of the dry air supply line 23 to the outlet side of the aftercooler 5 provided on the discharge side of the compressor body 1, and the suction side of the compressor body 1 is connected. A dry air supply port is connected to the suction pipe 103 to supply dry air.

According to this embodiment, when the compressor is out of operation, dry air is supplied to the intercooler or aftercooler provided on the discharge side of the compressor body, and dry air is also supplied to the suction side of the compressor body. , the reverse rotation of the compressor body can be prevented. In addition, it is possible to provide an oil-free air compressor with improved reliability by preventing oil from entering the compressor body.

FIG. 7 shows an oil-free screw compressor of Example 6 of the present invention. This embodiment is characterized in that an unloader 105 is provided between the air suction port 101 and the low-pressure stage suction pipe 103, and a dry air supply port 21A is provided between the unloader 105 and the low-pressure stage compressor main body 1a. Other configurations are the same as those of the fifth embodiment.

The unloader 105 has a valve inside that throttles the path of the compressed air, and it is a device that reduces the power during the unloading operation of the compressor by controlling it so that it opens during loading operation and closes during unloading operation. be. Since the stop of the compressor is usually an unloading stop, the unloader is closed during stoppage.

The dry air supplied from the dry air supply port 21A while the compressor is out of operation stays between the unloader 105 and the compressor body 1a, increasing the pressure inside the suction pipe 103.

In Example 5, the side of the air suction port 101 of the suction pipe 103 is open to the atmosphere. Although it must be larger than that supplied from 21B, in this embodiment, it is possible to reduce the amount supplied from the dry air supply port 21A.

According to this embodiment, the unloader is provided between the air suction port and the suction pipe of the low pressure stage, and the dry air supply port is provided between the unloader and the main body of the low pressure stage compressor. Also, it is possible to reduce the amount of dry air supplied from the dry air supply port to the suction side of the main body of the low-pressure stage compressor.

It should be noted that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. In addition, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

1…Compressor body
1a: Main body of low-pressure stage compressor
1b…High-pressure stage side compressor main body
2…Gear casing
3,3a,3b,3c...Motor
4…Intercooler
5…Aftercooler
6,6A,6B…drive gear
7…Driven gear
7A…Driven gear on the low pressure side
7B...High pressure side driven gear
8A…Oil pump drive gear
8B…Oil pump driven gear
13…Piping (middle stage)
14…Oil pump intake path
15…On-off valve
21,21A,21B…Dry air supply port
22…Supply valve
23…Dry air supply line
24…Oil pump
25…Check valve
26A, 26B...Air release valve
28…Air tank
32…Control panel
33A, 33B... Orifice
47…Oil reservoir
70…Brake device
100 Compressor
101 ... Air inlet
102 Compressed air outlet
103…Air intake pipe
105 Unloader

Claims

An oil-free air compressor comprising: an oil-free compressor body for compressing and outputting air; and a cooler connected to the compressor body for cooling the compressed high-temperature air,
a dry air supply mechanism that supplies dry air to the output side of the compressor body;
An oil-free air compressor provided with a mechanism for preventing reverse rotation of the compressor main body while the compressor is out of operation.
In the oilless air compressor according to claim 1,
An oil-free air compressor, wherein the compressor main body is an oil-free screw compressor.
In the oilless air compressor according to claim 1,
An oil-free air compressor, wherein the mechanism for preventing reverse rotation of the compressor body is a brake device.
In the oilless air compressor according to claim 1,
An oil-free air compressor, wherein the mechanism for preventing reverse rotation of the compressor body is a ratchet mechanism.
In the oilless air compressor according to claim 1,
an oil pump for supplying lubricating oil to each bearing;
an on-off valve provided on the suction side of the oil pump;
a single motor that drives the compressor body and the oil pump;
has
the oil pump is a gear pump,
The motor, the compressor body, and the oil pump are connected by gears,
An oil-free air compressor, wherein the on-off valve is closed while the compressor is out of operation.
In the oilless air compressor according to claim 5,
An oil-free air compressor, wherein the gear pump is a trochoid pump.
The oilless air compressor according to claim 1, further comprising:
An oil-free air compressor, wherein the dry air supply mechanism supplies dry air to the suction side of the compressor body.
In the oilless air compressor according to claim 7,
An unloader provided on the suction side of the main body of the compressor and having a valve for throttling the path of the compressed air therein,
An oil-free air compressor, wherein the dry air supply mechanism supplies dry air to a pipe between the unloader and the compressor body.
an oil-free low-pressure stage compressor body and a high-pressure stage compressor body that compress and output air;
An intermediate stage pipe that connects the low-pressure stage compressor body and the high-pressure stage compressor body, an intercooler provided in the intermediate stage that cools the compressed high-temperature air, and a high-pressure stage compressor body An oil-free air compressor comprising an aftercooler provided on the output side of
a dry air supply mechanism that supplies dry air to the intermediate stage piping;
An oil-free air compressor provided with a mechanism for preventing reverse rotation of the low-pressure stage side compressor main body while the compressor is out of operation.
In the oilless air compressor according to claim 9,
An oil-free air compressor, wherein the low-pressure stage compressor main body and the high-pressure stage compressor main body are oil-free screw compressors.
In the oilless air compressor according to claim 9,
An oil-free air compressor, wherein the mechanism for preventing reverse rotation of the low-pressure stage compressor main body is a brake device.
In the oilless air compressor according to claim 9,
An oil-free air compressor, wherein the mechanism for preventing reverse rotation of the low-pressure stage compressor main body is a ratchet mechanism.
In the oilless air compressor according to claim 9,
an oil pump for supplying lubricating oil to each bearing;
an on-off valve provided on the suction side of the oil pump;
a single motor that drives the low-pressure stage compressor main body, the high-pressure stage compressor main body, and the oil pump;
has
the oil pump is a gear pump,
The motor, the low-pressure stage compressor main body, the high-pressure stage compressor main body, and the oil pump are connected by gears,
An oil-free air compressor, wherein the on-off valve is closed while the compressor is out of operation.
The oilless air compressor according to claim 9, further comprising:
An oil-free air compressor, wherein the dry air supply mechanism supplies dry air to the suction side of the low pressure stage compressor main body.
In the oilless air compressor according to claim 14,
An unloader is provided on the suction side of the low-pressure stage compressor main body and has a valve inside for narrowing a path of compressed air,
An oil-free air compressor, wherein the dry air supply mechanism supplies dry air to a pipe between the unloader and the low-pressure stage compressor main body.