JP5331359B2 - Oil-cooled air compressor - Google Patents

Description

  The present invention relates to an oil-cooled air compressor.

  The oil-cooled air compressor includes an oil separator that separates compressed air and oil because oil is mixed into the air compressed by the compressor body. Although the oil separated by the oil separator is stored in the oil reservoir, a forming phenomenon may occur due to pressure fluctuation.

  Patent Document 1 discloses a screw compressor suitable for compressing combustible gas. In this patent document 1, since the lubricating oil stored in the oil separator on the discharge side of the compressor body causes foaming when the operation is stopped, a configuration for suppressing this is disclosed. Even when the operation is stopped, the oil separator portion is disclosed. By controlling the opening and closing of the valve so as to maintain the internal pressure, the occurrence of a forming phenomenon due to a sudden change in pressure is avoided.

Japanese Patent Publication No. 6-17679

  In an oil-cooled air compressor, since oil is mixed into compressed air, the oil separated and stored by the oil separator is in a state where fine bubbles of compressed air are mixed. A specific configuration example at this time will be described with reference to FIG.

  FIG. 6 is a system diagram of an oil-cooled air compressor. The air taken in through the suction throttle valve 3 is compressed by the compressor body 1. At this time, oil for lubrication is mixed while sealing a gap between rotors (not shown) in the compressor body 1. Therefore, compressed compressed air and oil are discharged from the discharge port of the compressor body 1 and sent to the oil separator 2.

  The oil separator 2 includes an oil separation mechanism 2a and an oil reservoir 2b. The oil separated by the oil separator 2 and mixed with fine bubbles is stored in the oil reservoir 2b. Then, the oil stored in the oil reservoir 2b is sent to the compressor body 1 via the oil pipe 11, and is again injected into the compressed air. At this time, a part of the oil sent from the oil reservoir 2 b to the compressor body 1 is cooled by the oil cooler 6. The amount of oil to be cooled is adjusted by the temperature control valve 22 together with the amount of oil flowing through the oil bypass pipe 14 that bypasses the oil cooler 6.

  On the other hand, the compressed air from which the oil has been separated by the oil separator 2 is supplied to the customer equipment from the unit outlet by opening the valve of the pressure regulating check valve 17 when the pressure becomes higher than the closing pressure of the pressure regulating check valve 17. The Since the compressed air from which the oil has been separated by the oil separator 2 has a high temperature, it is usually cooled by a discharge air cooler before being supplied to customer facilities.

  When the operation of the compressor main body 1 is stopped here, the compressed air is released until the internal pressure of the unit decreases below the closing pressure of the pressure regulating check valve 17, the internal pressure of the oil separator 2 decreases rapidly, and then Compressed air is discharged through the discharge solenoid valve 9, the control pipe 16, and the discharge amount adjusting means 10, and the internal pressure of the oil separator 2 is reduced to atmospheric pressure. This decrease in the internal pressure of the oil separator 2 is the main cause of the forming phenomenon. Details will be described below.

During operation, the oil separator 2 serves as a compressed air flow path, so that a high pressure state is maintained. When the pressure in the oil separator 2 at this time is P ₀ and the closing pressure P ₁ of the pressure regulating check valve is P ₁ (P ₀ > P ₁ ), when the operation is stopped, the pressure in the oil separator 2 starts from P _0. After rapidly decreasing to P ₁ , it decreases to atmospheric pressure. The oil existing in the oil circulation path in the unit including the oil cooler 6 is stopped when the oil circulation is stopped by stopping the operation of the compressor body at the same time when the pressure is suddenly reduced. 1 and the oil separator 2 are returned. Furthermore, the oil in the compressor body 1 also returns to the oil separator 2, and in particular, the oil level in the oil separator 2 rises.

  For example, about 50% of the total oil amount inside the unit is accumulated in the oil reservoir 2b of the oil separator 2 during operation, and about 10 to 15% flows to the compressor body 1 and about 35 to 40%. Taking the state of a general oil-cooled air compressor that flows in the oil circulation path of the oil cooler 6 or the like as an example, the influence of oil returning from the oil cooler 6 to the oil separator 2, In other words, the effect of oil return increases. A check valve 7 is provided on the upstream side of the oil cooler 6, but since the oil returns to the oil separator 2 through the oil bypass pipe 14, the oil level of the oil separator 2 rises. End up.

  In addition, since the internal pressure of the compressor main body 1, the oil separator 2, the oil pipe 11, and the oil cooler 6 also suddenly decreases, the compressed air contained in the oil accumulated in the oil reservoir 2 b in the oil separator 2 The fine bubbles rapidly expand. At this time, the oil level rise of oil and the rapid expansion of bubbles occur at the same time, the oil level is pushed up to the oil separation mechanism 2a of the oil separator 2, and the oil penetrates downstream of the oil separation mechanism 2a to separate the oil. Oil will blow out from the vessel 2. As a result, the oil is taken out and the oil is mixed into the discharge air. The blowing of oil not only causes a reduction in the quality of the air compressor, but also reduces the reliability of the apparatus because the lubricating oil is reduced in the apparatus.

Such a forming phenomenon is more likely to occur as the pressure P ₀ during operation of the compressor body 1 is higher, and thus tends to become a problem when providing a high-pressure specification air compressor. .

  In patent document 1, the oil blow-off from the oil separator 2 based on the forming phenomenon is prevented by preventing the internal pressure of the oil separator 2 from rapidly decreasing after the operation of the compressor body 1 is stopped. For example, as shown in FIG. 6, an air release electromagnetic valve 9 is provided at the outlet of the compressed air of the oil separator 2, and a valve operation chamber 3 a of the suction throttle valve 3 is connected via a control pipe 16, thereby releasing air electromagnetically. It is assumed that the valve 9 is controlled by the control board 21.

  When the compressor body 1 is in operation, the air release electromagnetic valve 9 is closed and the suction throttle valve 3 is opened. When the compressor body 1 is stopped, the air release electromagnetic valve 9 is opened and the internal pressure of the oil separator 2 is opened in the valve operating chamber 3a. And the suction throttle valve 3 is closed. In this way, by closing the suction throttle valve 3 instantaneously at the time of stoppage, the rapid expansion associated with the reduction of the ambient pressure of the compressed air bubbles is suppressed, and when the operation is stopped, the oil from the oil separator 2 based on the oil forming phenomenon is suppressed. Prevents blowout.

  In this way, by preventing the pressure inside the oil separator 2 from rapidly decreasing after the operation of the compressor body 1 is stopped, the oil is blown out from the oil separator 2 based on the forming phenomenon, and the oil is discharged to the discharge air. Mixing can be prevented.

  However, the effect of suppressing the blow-out of oil greatly depends on the volume of the oil separator 2. For example, the smaller the volume of the oil separator 2, the longer the time for maintaining the pressure in the oil separator 2 must be increased. was there. In addition, a state in which a high pressure is maintained inside the unit for a long time after the operation of the compressor is stopped is not necessarily effective from the viewpoint of safety.

  On the other hand, if the volume of the oil separator 2 is increased in order to prevent oil and suddenly expanded bubbles due to the forming phenomenon from reaching the oil separation mechanism 2a, the weight of the material increases and the material cost increases. Not only can it not be done, but it also increases the size of the entire unit.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an oil-cooled air compressor that is improved in quality and reliability without increasing the size of the apparatus.

In order to achieve the above object, the first feature of the present invention is that a compressor body for compressing air, an oil separator for separating and storing oil mixed in compressed air from the compressor body, and the oil An oil pipe that constitutes an oil circulation path for supplying oil separated by the separator to the compressor body, an oil cooler that is provided in the oil circulation path and cools the oil flowing through the oil pipe, and the oil cooler A first bypass pipe that bypasses the oil cooler, a temperature control valve that controls a flow of oil flowing through the oil cooler and the first bypass pipe, and valves provided on the upstream side and the downstream side of the oil cooler, respectively. And a second bypass pipe having a smaller diameter than the oil pipe bypassing the valve means provided on the downstream side of the oil cooler, and the valve means provided on the downstream side of the oil cooler. Open the compressor at the start of operation and operate the compressor. It lies in that a control device for controlling to close at shutdown.

The second feature is that the compressor body that compresses air, the oil separator that separates and stores the oil mixed in the compressed air from the compressor body, and the oil separated by the oil separator An oil pipe that constitutes an oil circulation path that supplies the compressor body, an oil cooler that is provided in the oil circulation path and that cools the oil flowing through the oil pipe, and a first bypass pipe that bypasses the oil cooler A temperature control valve that controls the flow of oil flowing through the oil cooler and the first bypass pipe, a check valve provided on the upstream side of the oil cooler, and a downstream side of the oil cooler A provided solenoid valve, a second bypass pipe having a smaller diameter than a pipe to which the solenoid valve is bypassed and to which the solenoid valve is attached, and the solenoid valve is opened when the compressor is started and closed when the compressor is stopped. And a control device for controlling

Among the above-described features of the present invention, more preferred specific embodiments are as follows.
(1) In the above-described one having the first feature, the check valve as the upstream side of the valve means of the oil cooler, that had use a solenoid valve as the valve means downstream.
(2) The second bypass pipe having a cross-sectional area of 4 to 8% of the cross-sectional area of the oil pipe or the first bypass pipe is used.
(3) When the operation of the compressor is stopped, the control device is configured such that the volume of the oil-free portion of the total volume of the oil separator is larger than the volume of oil returning into the oil separator. Controlling the solenoid valve.
(4) The control device controls the solenoid valve so that the oil returning to the oil separator is less than half of the total volume of the oil separator when the compressor is stopped.
(5) The second bypass pipe is disposed so as to pass above the solenoid valve.

  ADVANTAGE OF THE INVENTION According to this invention, the oil-cooled air compressor which aimed at the improvement of quality and reliability can be provided, without causing the enlargement of an apparatus.

  In the following, the best mode for carrying out the present invention will be described. As shown in FIGS. 1 and 5, the oil-cooled air compressor according to this embodiment is generated by a compressor body 1 that compresses air and oil is mixed into the compressed air, and the compressor body 1. An oil separator 2 that separates oil from the compressed air, an oil supply system that constitutes an oil circulation path that supplies the oil separated by the oil separator 2 to the compressor body 1, and an air provided in the oil supply system Or the oil cooler 6 which cools oil by heat exchange with cooling water is provided at least.

  In addition, valve means 7 and 8 are provided in the oil circulation paths on the upstream side and the downstream side of the oil cooler 6, respectively. An oil pipe 14 that bypasses the oil cooler 6 is provided. The oil pipe 14 branches from a temperature control valve 22 provided on the upstream side of the oil cooler 6, and the amount of oil flowing to the oil cooler 6 is controlled according to the temperature.

  The valve means 8 is controlled in accordance with the operation of the compressor. Specifically, the oil cooler 6 is opened simultaneously with the operation of the compressor to flow the oil, and the oil flow is simultaneously performed with the operation of the compressor stopped. Control to stop. In this embodiment, as shown in FIGS. 1 and 5, a check valve 7 is provided on the upstream side of the oil cooler 6, and the temperature control valve is connected via an oil pipe 14 from an outlet on the downstream side of the oil cooler 6. A stop electromagnetic valve 8 is provided in the piping path to 22.

  In addition, an oil pipe 15 that bypasses the stop solenoid valve 8 is provided. The oil pipe 15 is smaller in diameter than the pipe constituting the pipe path from the oil cooler 6 to the temperature control valve 22. By providing the oil pipe 15, it is possible to reduce an increase in the oil level while bubbles that have rapidly expanded after the operation of the compressor is stopped are generated in the oil separator 2. In particular, it is possible to suppress an abrupt increase in the oil level in the oil reservoir 2b due to the return of oil from the oil cooler 6 to the oil separator 2, and to suppress the influence of bubble expansion. The oil pipe 15 can be expected to have the same effect even when the check valve 7 is bypassed. However, the oil pipe 15 will be described below as bypassing the stop solenoid valve 8.

  In this way, rapid expansion of fine bubbles of compressed air can be stopped inside the oil separator 2, so that the oil is blown out from the oil separator 2 and the oil flows out to the discharge air based on the forming phenomenon. It becomes possible to prevent.

  In addition, since it is not necessary to make the oil separator 2 larger than necessary, not only can the size of the oil separator 2 be kept to a minimum and the cost including the material cost can be reduced, but also the unit size can be reduced. It becomes possible. Hereinafter, more specific examples will be described with reference to the drawings.

  A first example according to this embodiment will be described with reference to FIG. FIG. 1 is a system diagram of an oil-cooled air compressor according to the first embodiment. Air in the atmosphere enters the suction throttle valve 3 from the suction pipe 13 through the suction filter 4, and the air passing through the pipe line a connecting the suction throttle valve 3 and the compressor body 1 is compressed by the compressor body 1. The The air sucked into the compressor body 1 is compressed by a rotor (not shown) in the compressor body 1 while receiving oil from the oil pipe 11 in the compressor body 1. In the compressor body 1, the gap between the rotors is sealed and lubricated by receiving lubrication, and thus compressed compressed air and oil are discharged from the discharge port of the compressor body 1, and the lubricated oil At the same time, the compressed gas is discharged from the pipe b to the oil separator 2.

  The oil separator 2 includes an oil separation mechanism 2a in the upper part, and a lower part of the oil separation mechanism 2a is an oil reservoir 2b. Therefore, the compressed air and oil that have entered the oil separator 2 are separated by the oil separation mechanism 2a, and the separated oil drops and is temporarily stored in the oil reservoir 2b.

  The compressed air from which the oil has been separated is sent out to the discharge air pipe 12. The discharge air pipe 12 is a pipe disposed on the downstream side of the oil separator 2, and serves as a compressed air flow path after the oil is separated by the oil separation mechanism 2a. The discharge air pipe 12 is provided with a pressure regulating check valve 17 and a discharge air cooler 5. When the compressed air exceeds the closing pressure of the pressure regulating check valve 17, the valve of the pressure regulating check valve 17 is opened. When the pressure regulating check valve 17 is opened, the compressed air is cooled by the discharge air cooler 5 and then discharged from the unit discharge port and supplied to the customer facility.

  On the other hand, the oil separated by the oil separation mechanism 2 a and accumulated in the oil reservoir 2 b is injected into the compressor main body 1 through an oil pipe 11 that connects the oil separator 2 and the compressor main body 1. The oil pipe 11 is a pipe that forms a part of an oil circulation path provided separately from the pipe b that is a flow path of compressed air that connects the compressor body 1 and the oil separator 2. It has a bifurcation. In the present embodiment, as shown in FIG. 1, a first oil bypass pipe (hereinafter referred to as “oil bypass pipe A”) 14 branched by the temperature control valve 22 is provided. The oil bypass pipe A <b> 14 bypasses the check valve 7, the oil cooler 6, and the stop electromagnetic valve 8 provided in the oil pipe 11.

  The temperature control valve 22 is controlled by a temperature detector (not shown), and when the oil temperature is low, oil flows into the oil bypass pipe A14 and lubrication is performed to the compressor body 1. When the oil temperature is high, the oil flows through the check valve 7 and flows into the oil cooler 6, where it is cooled and then injected into the compressor body 1.

  In the present embodiment, a second oil bypass pipe (hereinafter referred to as “oil bypass pipe B”) that bypasses the stop solenoid valve 8 provided in the oil pipe 11 on the downstream side of the oil cooler 6 is provided. Therefore, the oil cooled by the oil cooler 6 when the oil temperature is high passes through the stop solenoid valve 8 and the oil bypass pipe B15 that bypasses the stop solenoid valve 8, and then is injected into the compressor body 1.

  The oil bypass pipe B15 is arranged so that the pipe is raised from before the stop solenoid valve 8 and passes above the stop solenoid valve 8, and as will be described later, after the pressure is lowered when the compressor is stopped, the oil cooler 6 to reduce oil return from inside.

  Next, valve opening / closing control in this embodiment will be described with reference to FIGS. FIG. 2 is a diagram showing a state of valve opening / closing control in the present embodiment, and FIG. 3 is a flowchart relating to valve opening / closing control. The valve of the present embodiment is controlled by the control board 21 (control device). Specifically, as shown in FIG. 2, the venting electromagnetic valve 9 opens the valve when starting, unloading, and stopping, The valve is controlled to close during load operation. Therefore, since the air release solenoid valve 8 is closed during the load operation, the suction throttle valve 3 is opened, and the compressor body 1 compresses air. The air release solenoid valve 9 is provided in the control pipe 16 that connects the compressed air flow path downstream of the oil separator 2 and the valve operation chamber 3 a of the suction throttle valve 3. The opening / closing control as shown in FIG.

  The stop electromagnetic valve 8 provided in the oil pipe 11 is controlled so that the valve is opened simultaneously with the start of the operation of the compressor body 1 and is closed simultaneously with the operation stop of the compressor body 1. Therefore, when the operation of the compressor main body 1 is stopped, the stop electromagnetic valve 8 is closed, so that the oil stored in the oil cooler 6 is suppressed from returning rapidly to the compressor main body 1 and the oil separator 2. The

  That is, simultaneously with the start of operation of the compressor body 1, the stop solenoid valve 8 is opened, the oil pipe 11 constituting the oil circulation path is opened, and at the start-up operation after the operation start (for example, 15 seconds after the operation start). The air discharge electromagnetic valve 9 is closed, and the suction throttle valve 3 is opened to perform the road operation. The load / unload is switched by opening / closing the air release solenoid valve 9. Regardless of loading / unloading, oil that needs to be cooled by the oil cooler 6 flows to the check valve 7, and the oil is circulated. The flow rate of oil flowing to the cooler 6 is controlled.

  When stopping the operation of the compressor body 1, the air discharge solenoid valve 9 is opened, the pressure in the valve operation chamber 3 a is increased via the control pipe 16, and the suction throttle valve 3 is closed. At this time, the internal pressure of the oil separator 2 is prevented from dropping suddenly by the air discharge amount adjusting means 10. Furthermore, by closing the stop solenoid valve 8, oil return from the oil circulation path including the oil cooler 6 to the oil separator 2 via the oil bypass pipe A14 is prevented. In addition, since the check valve 7 is provided on the upstream side of the oil cooler 6, oil return that flows back through the oil cooler 6 and returns to the oil separator 2 is prevented.

  According to the control, an effect of suppressing the oil blowing due to the forming phenomenon is recognized, but the inside of the oil cooler 6 becomes a high pressure state when the operation is stopped. For example, when the internal pressure of the oil separator 2 is 1 MPa during operation and the closing pressure of the pressure regulating check valve 17 is 0.44 MPa, the internal pressure in the oil separator 2 is suddenly changed from 1 MPa to 0.44 MPa. Then, even if the internal pressure of the oil separator 2 is reduced by releasing the compressed air through the air release solenoid valve 9, the control pipe 16 and the air release amount adjusting means 10, the oil cooler 6 to the oil separator 2. However, it is possible to prevent the oil from being blown out by suppressing the rapid oil level rise, but the inside of the oil cooler 6 is maintained at a high pressure of about 1 MPa.

  In the present embodiment, the oil bypass pipe B15 is provided as described above, and the high pressure state is maintained by communicating the upstream side and the downstream side of the stop solenoid valve 8 even when the stop solenoid valve 8 is closed. Inconvenience due to being done is avoided.

  As described above, in the present embodiment, in order to suppress the oil blowout due to the forming phenomenon, the oil bubbling time in the oil reservoir 2b (depending on the pressure change) and the time required for oil return (cause of oil level rise) The relationship with is a problem. Therefore, a configuration considering these will be described.

  When the operation of the compressor main body 1 is stopped, the oil circulating in the unit returns from the compressor main body 1 and the oil cooler 6 to the oil separator 2 and the oil level in the oil separator 2 rises. About 50% of the total oil amount inside the unit is accumulated in the oil reservoir 2b of the oil separator 2 during operation, and about 10 to 15% of the total flows to the compressor main body 1 and about 35 to 35% of the total amount. Since 40% flows to the oil cooler 6, the rise in the oil level of the oil separator 2 after the stop of operation is the return of oil flowing from the oil cooler 6 to the oil separator 2 through the oil bypass pipe A 14. A large impact.

  Therefore, stopping the oil return from the oil cooler 6 after the operation of the compressor body 1 is stopped is an effective means for suppressing the oil level rise in the oil separator 2. If the return is completely stopped, the pressure in the oil cooler 6 will not drop. Therefore, in order to reduce the pressure in the oil cooler 6, it is necessary to reduce the pressure by flowing out a small amount of oil remaining in the oil cooler 6. However, if the compressor body 1 stops and the oil pressure decreases, Since the forming phenomenon occurs from all of the oil, the forming phenomenon also occurs in the oil pipe 11 due to a decrease in hydraulic pressure.

  It is assumed that the forming phenomenon occurs immediately after the operation is stopped, and that the forming phenomenon is converged within 3 minutes, and the pressure in the oil cooler 6 is effectively reduced while minimizing the oil return. Therefore, the pipe diameter of the oil bypass pipe B15 is important. In the present embodiment, the stop electromagnetic valve 8 that can be opened and closed is used and the opening degree is not controlled. Therefore, the pipe diameter of the oil bypass pipe B15 is particularly problematic. By using a pipe diameter of the oil bypass pipe B15 that is smaller than the pipe diameter to which the stop solenoid valve 8 is attached, when the stop solenoid valve 8 is closed, oil or air is less than the open state. It is difficult to flow. In other words, it is important to control so that the amount of oil or air flowing through the oil circulation path is less than that during operation immediately after the operation is stopped.

  Hereinafter, a valve capable of switching control of opening and closing is used as the stop electromagnetic valve 8, the total volume of the oil separator 2 is 11 liters, the total oil amount is 10 liters, and the internal pressure when the compressor is stopped is about 1 MPa to 0.44 MPa. The relationship between the amount of oil or air flowing through the oil circulation path and the pipe diameter will be described with reference to a case where the pressure decreases.

  As an example, during the operation of the compressor, about 5 liters of oil is stored in the oil reservoir 2b of the oil separator 2, and the oil component that rises due to the forming phenomenon is caused by the oil separation mechanism 2a positioned above the oil reservoir 2b. In order not to exceed, it is necessary to suppress the oil amount to half or less of the total volume of the oil separator 2, that is, to suppress the oil return amount to 0.5 liter or less. A problem due to the forming phenomenon is likely to occur when 2 liters or more of oil returns to the oil separator 2 before the bubbling converges. Therefore, such a case is defined as a failure.

  That is, the oil return from the oil cooler 6 to the oil separator 2 is kept below 0.5 liters while foaming is generated after the operation is stopped, and the operating pressure of the oil cooler 6 is reduced to the atmospheric pressure. It is important to keep the time taken to be within 2 minutes, which is considered to be no problem for safety (the time is shorter than the time for the forming phenomenon to converge). As a result, it is desirable that the ratio of the cross-sectional area of the oil bypass pipe B15 to the cross-sectional area of the oil pipe 11 be 4 to 8%.

  FIG. 4 is a diagram showing the relationship between the diameter of the oil bypass pipe B15, the ratio of the cross-sectional area of the pipe diameter where the stop solenoid valve 8 is provided, the decompression time in the oil cooler 6, and the forming in the oil separator 2. Yes, it shows the result of confirming the correctness of the above-mentioned cross-sectional area ratio of 4-8%.

  According to FIG. 4, the diameter of the oil bypass pipe B15 that allows the internal pressure of the oil cooler 6 to be reduced to atmospheric pressure within 2 minutes is required to be φ4 or more, reaching the forming oil separation mechanism 2a. It can be seen that the pipe diameter of the oil bypass pipe B15 for preventing this needs to be φ4 or less.

  From this result, the pipe diameter of the oil bypass pipe B15 is better to be φ4 than the pipe diameter φ16.8 of the oil circulation path, and the ratio of the cross-sectional area of the bypass pipe B15 to the cross-sectional area of the oil pipe 11 at this time Is 5.7%, and the cross-sectional area ratio is within the range of 4 to 8%.

Thus, the check valve 7 and the stop solenoid valve 8 are closed, and the upstream side and the downstream side of the stop solenoid valve 8 are communicated even when the stop solenoid valve 8 is closed by the oil bypass pipe B15. In order to prevent the oil from rapidly returning to the oil separator 2 while reducing the pressure in the oil cooler 6 in a short time after the operation is stopped, the sectional area of the pipe of the oil bypass pipe B15 is set to It is necessary to make it 4 to 8% of the cross-sectional area, and until the forming phenomenon is settled,
Of the total volume of the oil separator, the relationship between the volume of the oil-free portion> the volume of the oil in the oil separator, that is, the oil stored in the oil separator 2 is kept below half of the total volume of the oil separator 2 Thus, even if fine bubbles of compressed air mixed in the oil rapidly expand, the oil cannot be pushed up to the oil separation mechanism 2b of the oil separator 2 together with the oil.

  Therefore, according to the present embodiment, it is possible to prevent the oil from being blown out from the oil separator 2 based on the forming phenomenon and the oil from being mixed into the discharge air.

  A second embodiment of the present invention will be described with reference to FIG. Except that the stop solenoid valve 8 and the oil bypass pipe B15 are arranged in the oil bypass pipe A14, this is the same as in the first embodiment. In this embodiment, the pressure in the pipe path of the oil cooler 6 is compared with the first embodiment. There is an advantage that the loss can be kept low.

1 is a system diagram of an oil-cooled air compressor according to a first embodiment. The figure which shows the state of the opening / closing control of a valve. The flowchart which concerns on the opening / closing control of a valve. The figure which shows the relationship between the cross-sectional area ratio of piping diameter, pressure reduction time, and forming. The systematic diagram of the oil-cooled air compressor which concerns on 2nd Example. The system diagram of an oil-cooled air compressor.

Explanation of symbols

  1: compressor body, 2: oil separator, 2a: oil separation mechanism, 2b: oil reservoir, 3: suction throttle valve, 3a: valve operation chamber, 4: suction filter, 5: discharge air cooler, 6 : Oil cooler, 7: Check valve, 8: Stop solenoid valve, 9: Air release solenoid valve, 10: Air discharge amount adjusting means, 11: Oil pipe, 12: Discharge air pipe, 13: Suction pipe, 14: Oil bypass pipe A (oil pipe, first oil bypass pipe), 15: oil bypass pipe B (oil pipe, second oil bypass pipe), 16: control pipe, 17: pressure regulating check valve, a: pipe Path, b: pipeline, 21: control board (control device), 22: temperature control valve.

Claims (7)

A compressor main body that compresses air, an oil separator that separates and stores oil mixed in the compressed air from the compressor main body, and an oil that supplies oil separated by the oil separator to the compressor main body An oil pipe that constitutes a circulation path, an oil cooler that is provided in the oil circulation path and cools oil flowing through the oil pipe, a first bypass pipe that bypasses the oil cooler, the oil cooler, and the oil cooler A temperature control valve for controlling the flow of oil flowing through the first bypass pipe, valve means provided on the upstream side and downstream side of the oil cooler, and a downstream side of the oil cooler among the valve means. The valve means provided is bypassed, the second bypass pipe having a smaller diameter than the oil pipe, and the valve means provided on the downstream side of the oil cooler are opened when the compressor is started and closed when the compressor is stopped. And a control device for controlling Oil-cooled air compressor.   A compressor main body that compresses air, an oil separator that separates and stores oil mixed in the compressed air from the compressor main body, and an oil that supplies oil separated by the oil separator to the compressor main body An oil pipe that constitutes a circulation path, an oil cooler that is provided in the oil circulation path and cools oil flowing through the oil pipe, a first bypass pipe that bypasses the oil cooler, the oil cooler, and the oil cooler A temperature control valve for controlling the flow of oil flowing through the first bypass pipe, a check valve provided on the upstream side of the oil cooler, an electromagnetic valve provided on the downstream side of the oil cooler, A second bypass pipe that bypasses the solenoid valve and has a smaller diameter than the pipe to which the solenoid valve is attached; and a control device that controls the solenoid valve to be opened when the compressor is started and closed when the compressor is stopped. Oil-cooled air compressor.   The oil-cooled air compressor according to claim 1, wherein a check valve is used as the valve means upstream of the oil cooler, and an electromagnetic valve is used as the valve means downstream.   4. The second bypass pipe having a cross-sectional area of 4 to 8% of the cross-sectional area of the oil pipe or the first bypass pipe is used. Oil-cooled air compressor.   When the compressor is stopped, the control device is configured so that the volume of the oil-free portion of the total volume of the oil separator is larger than the volume of oil returning into the oil separator. 4. The oil-cooled air compressor according to claim 2, wherein the valve is controlled.   The said control apparatus controls the said solenoid valve so that the oil which returns to the said oil separator at the time of the operation stop of the said compressor becomes below half of the total volume of the said oil separator. Or the oil-cooled air compressor of 3.   The oil-cooled air compressor according to claim 2 or 3, wherein the second bypass pipe is disposed so as to pass above the solenoid valve.

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