JPH05340372A - Oil cooled air compressor - Google Patents

Abstract

PURPOSE:To prevent a drain from separating, simplify the whole structure and improve safety or the like by retaining effectively the temperature of oil in an oil tank. CONSTITUTION:A pressure switch 20 and temperature switch 23 are OR connected to an electromagnetic switch 42 to electrify an electric motor 8 through the electromagnetic switch 42 when either of the respective switches 20, 23 is closed. Thus, when pressure in a discharge piping reaches the upper limit value, the temperature of lubricating oil exceeds a predetermined temperature, both switches 20, 23 are opened and continuous running mode is shifted to intermittent running mode, then the electromagnetic switch 42 is excited by closing of the temperature switch 23 if the temperature of lubricating oil gets lower than a predetermined temperature and the electric motor 8 is rotatably driven to generate compression heat in a compressor body and retain the heat of lubricating oil by the compression heat.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-cooled air compressor used as, for example, an oil-cooled scroll compressor, a vane compressor, a screw compressor or the like.

[0002]

2. Description of the Related Art FIGS. 5 to 8 show a scroll compressor as an example of an oil-cooled air compressor according to the prior art.

In the figure, reference numeral 1 denotes a scroll type compressor body, which is provided rotatably with a casing 2 and one side in the axial direction of the casing 2, the tip side being inside the casing 2. Drive shaft 3 extended to crank
And a orbiting scroll rotatably provided on the crank of the drive shaft 3, and fixed to the other side in the axial direction of the casing 2 so as to face the orbiting scroll, and a plurality of compression chambers are defined between the orbiting scroll and the orbiting scroll. The casing 2 is generally composed of a fixed scroll (not shown), and a suction port 4 is formed on the outer peripheral side of the casing 2.

The compressor body 1 includes pulleys 5,
6 and a driving belt 7 are connected to an electric motor 8, and the rotation of the electric motor 8 compresses the air sucked from the suction port 4 in each compression chamber, and the compressed air is discharged to the fixed scroll. The oil is discharged from an oil tank (not shown) into an oil tank 15 described later.

Reference numeral 9 denotes a suction unloader provided on the upper part of the compressor body 1 so as to cover the suction port 4. The suction unloader 9 has a valve chamber 10A inside and an inlet 10B as shown in FIG. , The valve casing 10 in which the outlet 10C and the control pressure port 10D are formed, and the inlet 10B is slidably provided in the valve chamber 10A of the valve casing 10 and compressed by the compressed air supplied from the control pressure port 10D. A valve body 11 that opens and closes, a valve spring 12 that normally urges the valve body 11 in the valve closing direction, and a throttle passage 13 formed in the valve body 11 to connect the valve chamber 10A and the control pressure port 10D. Is roughly composed of
A suction filter 14 is attached to the inlet 10B.

In the suction unloader 9, when the compressor main body 1 is driven by the electric motor 8 and the suction port 4 side becomes negative pressure, the valve element 11 opens against the spring force of the valve spring 12. When the outside air is made to flow into the suction port 4 from the inflow port 10B to be in the load state, and when the control pressure (compressed air) is supplied through the control pressure port 10D, the control pressure and the spring force of the valve spring 12 are The valve is closed by shutting off between the inflow port 10B and the suction port 4 to bring the valve into an unloading state.

15 is located on the discharge port side of the compressor body 1,
An oil tank provided to accommodate the compressor body 1, the oil tank 15 including a tank body 15A containing a lubricating oil F for lubricating and cooling the compressor body 1, and the tank. Air exhaust port 15B formed on the other side of the main body 15A
And the oil separation filter 1 attached to the air outlet 15B
5C and a discharge side cover 15D provided so as to cover the air discharge port 15B are configured as an oil separator, and are connected to an air tank 17 or the like via a discharge pipe 16 connected to the discharge side cover 15D. .. And the oil tank 15
Supplies the lubricating oil F into the compressor body 1, separates and collects the lubricating oil F in the compressed air discharged from the discharge port by the oil separation filter 15C, and clean compressed air is discharged through the discharge pipe 16. The air is supplied to the air tank 17.

Reference numeral 18 denotes a temperature adjusting section provided in the compressor main body 1. The temperature adjusting section 18 has an oil passage 18A connected to each section of the compressor main body 1 and three systems provided in the middle of the oil passage 18A. And a oil cooler (neither is shown) connected via the temperature control valve. The temperature adjusting unit 18 adjusts the oil temperature of the lubricating oil F supplied to each part of the compressor body 1 by adjusting the amount of oil flowing to the oil cooler according to the oil temperature.

Reference numeral 19 is a pressure regulating valve provided with a check valve provided in the middle of the discharge pipe 16, and 20 is a pressure switch as a pressure detector provided on the discharge pipe 16 located on the downstream side of the pressure regulating valve 19. Each of the pressure switches 20 is composed of normally closed contacts, and as shown in FIG. 8 to be described later, the contacts are opened when the pressure in the discharge pipe 16 reaches the upper limit value P1 and restored when the pressure reaches the lower limit value P2. It is designed to close the contacts.

Reference numeral 21 is a control pressure pipe arranged between the discharge pipe 16 and the control pressure port 10D of the valve casing 10, and 22 is a normally closed solenoid valve provided in the middle of the control pressure pipe 21. As will be described later, the solenoid valve 22 is opened and closed according to the opening and closing of the pressure switch 20, and the pressure of the compressed air in the discharge pipe 16 is supplied to the suction unloader 9 as a control pressure. ..

Reference numeral 23 denotes a temperature switch provided in the oil tank 15 as an oil temperature detecting means.
Is a normally closed contact as shown in FIGS. 7 and 8, and the contact is opened when a predetermined temperature T1 is reached.

Reference numeral 24 denotes a heater provided in the oil tank 15. The heater 24 keeps the temperature of the lubricating oil F in the oil tank 15 by causing a current to flow and generate heat when the electric motor 8 is stopped.

Next, the circuit configuration of the oil-cooled air compressor described above will be described with reference to FIG.

Reference numeral 25 denotes a three-phase AC power supply, and 26 denotes a power supply line provided by connecting the three-phase AC power supply 25 and the electric motor 8, and a normally closed contact 27A is provided in the middle of the power supply line 26.
Is provided with a temperature relay 27.

Reference numeral 28 denotes a temperature protector composed of a normally closed contact provided in the vicinity of the discharge port of the compressor body 1, and the temperature protector 28 detects the temperature (discharge temperature) of the compressed air discharged from the compressor body 1. However, the contact is opened when the discharge temperature reaches a predetermined temperature or higher.

Reference numeral 29 is a start switch composed of normally open contacts, 3
0 is a stop switch composed of normally closed contacts connected in series to the start switch 29, 31 is a start relay connected in series to each of the switches 29 and 30 and having normally open contacts 31A, 31B and 31C, respectively. The starting relay 31
Has a first normally-open contact 31A connected in parallel to the start switch 29 to form a self-holding circuit, and a second normally-open contact 31B.
Is connected in series to an electromagnetic switch 32 described later, and the third normally open contact 31C is connected in series to the heater 24.

Reference numeral 32 is a normally open contact 31B of the starting relay 31.
Shows an electromagnetic switch which is connected to the power supply line 26 via the pressure switch 20 and the temperature switch 23 and is OR-connected,
The normally open contact 32A of the electromagnetic switch 32 has a power supply line 26.
The other normally open contact 32B is connected to the temperature switch 23 in series, and the normally closed contact 32C is connected to the heater 24 and a pilot lamp 34 described later. The electromagnetic switch 32 is excited when the normally-open contact 31B of the starting relay 31 is closed, whereby the normally-open contact 32B is opened.
A is closed to supply power to the electric motor 8, and the normally closed contact 32C is opened to stop the heater 24. The other normally open contact 32B of the electromagnetic switch 32 is
As will be described later, after the electric motor 8 is stopped, the discharge pipe 1
The pressure in 6 drops to the lower limit P2 and the pressure switch 20
This is because the restart of the electric motor 8 is not permitted until the above is closed.

Reference numeral 33 denotes an unload relay which is connected in parallel to the electromagnetic switch 32 and has a normally closed contact 33A. The normally closed contact 33A of the unload relay 33 is connected in series to the electromagnetic valve 22. Then, the unload relay 3
3 is demagnetized when the pressure in the discharge pipe 16 reaches the upper limit value P1 and the pressure switch 20 is opened, and the normally closed contact 33A.
Is closed, power supply to the solenoid valve 22 is allowed, compressed air is supplied to the suction unloader 9, and the unloading state is set.

Reference numeral 34 denotes a pilot lamp, which is turned on while the electromagnetic switch 32 is demagnetized and the normally closed contact 32C is closed, that is, while the electric motor 8 is stopped. Is becoming

The oil-cooled air compressor according to the prior art has the above-mentioned structure. Next, the operation will be described with reference to FIG.
Will be described with reference to.

First, when the start switch 29 is turned on, the start relay 31 is excited and each normally open contact 31A,
31B and 31C are closed, and the starting relay 31 is self-held by the normally open contact 31A.

The normally open contact 31 of the starting relay 31
When B is closed, the electromagnetic switch 32 is excited and turned on, closing the normally open contacts 32A and 32B and the normally closed contact 32C. As a result, the current from the three-phase AC power supply 25 causes the normally open contact 3 of the electromagnetic switch 32 to open.
Power is supplied to the electric motor 8 via 2A,
Drives to rotate.

Immediately after starting, the pressure in the discharge pipe 16 is low and the temperature of the lubricating oil F is low, so the pressure switch 20 and the temperature switch 23 are closed. Therefore, the unloading relay 33 is excited to open the normally closed contact 33A, and the power supply to the solenoid valve 22 is stopped to bring it into the loaded state.

When the rotation of the electric motor 8 is transmitted to the drive shaft 3 via the pulleys 5, 6 and the like, the orbiting scroll orbits with respect to the fixed scroll, and the suction unloader 9 and the suction port 4 are used. The compressed air is compressed in each compression chamber, and the compressed air is discharged together with the lubricating oil F into the oil tank 15 through the discharge port. As a result, the compressed air is discharged from the oil tank 15 into the discharge pipe 16 after the lubricating oil F is removed by the oil separation filter 15C, and is sent into the air tank 17 via the pressure regulating valve 19 and the like.

On the other hand, by this compression operation, the discharge pipe 16
When the internal pressure rises to the upper limit P1, pressure switch 2
0 opens, whereby the unloading relay 33 is demagnetized to close the normally closed contact 33A, permitting power supply to the solenoid valve 22 and supplying the suction unloader 9 with compressed air in the discharge pipe 16. , The discharge port, the discharge pipe 16, the suction unloader 9, and the suction port 4 are brought into an unloading operation state in which the operation is performed in a closed cycle.

When the pressure in the discharge pipe 16 decreases and reaches the lower limit value P2, the pressure switch 20 is closed, the unloading relay 33 is excited and the solenoid valve 22 is closed, and the load operation state is reached. Becomes

That is, as shown in the section A in FIG. 8, when the temperature of the lubricating oil F is below the predetermined temperature T1, the temperature switch 23 which is OR-connected to the electromagnetic switch 32 together with the pressure switch 20 is closed. Therefore, power supply to the electromagnetic switch 32 is secured by the temperature switch 23, and the electric motor 8 is continuously operating. Therefore, in this section A, the electric motor 8 continues to be rotationally driven during the unloading state due to the opening of the pressure switch 20, which is a continuous operation mode.

Next, when the temperature of the lubricating oil F rises due to the heat of compression generated during the compression operation and reaches a predetermined temperature T1,
The temperature switch 23 is opened. In this state, the discharge pipe 1
When the pressure in 6 reaches the upper limit P1 and the pressure switch 20 is opened, the power supply to the electromagnetic switch 32 is cut off and the normally open contacts 32A and 32B are opened, and the operation of the electric motor 8 is stopped. As a result, the electric motor 8 stops operating until the pressure in the discharge pipe 16 drops to the lower limit value P2 and the pressure switch 20 is closed, and depends exclusively on the opening and closing of the pressure switch 20.

That is, as shown in the section B in FIG. 8, when the temperature of the lubricating oil F becomes equal to or higher than the predetermined temperature T1, the temperature switch 23 is opened and the electromagnetic switch via the temperature switch 23 is opened. Since the power supply path to 32 is cut off, the electromagnetic switch 32 operates in conjunction with the opening and closing of the pressure switch 20. Therefore, in this section B, the electric motor 8 stops during the unload state while the pressure switch 20 is open, and the electric motor 8 is driven during the load state while the pressure switch 20 is closed. It will be in the intermittent operation mode.

Here, when both the pressure switch 20 and the temperature switch 23 are opened and the electromagnetic switch 32 is demagnetized, the normally open contact 32B is opened. Therefore, the temperature of the lubricating oil F is kept at a predetermined level during the intermittent operation mode described above. Even if the temperature of the temperature switch 23 drops below the temperature T1 and the temperature switch 23 returns (closes) earlier than the pressure switch 20, power is not supplied to the electromagnetic switch 32 via the temperature switch 23.

On the other hand, regarding the operation of the heater 24,
Since the normally open contact 31C of the starting relay 31 and the normally closed contact 32C of the electromagnetic switch 32 are AND-connected to the heater 24, as shown in FIG. Is energized and power is not supplied while the normally closed contact 32C is open, while power is supplied while the electromagnetic switch 32 is demagnetized and the normally closed contact 32C is closed. Therefore, as shown in FIG. 8, the heater 24 generates heat only when the electric motor 8 is stopped and the heat of compression of the compressor body 1 is not generated, so that the lubricating oil F is kept warm.

[0032]

In the conventional oil-cooled air compressor described above, a heater 24 is provided in the oil tank 15, and when the electric motor 8 is stopped, the heater 24 is heated to generate the lubricating oil F. Since it is designed to keep warm, the drain due to the moisture in the compressed air discharged from the compressor body 1 can be separated in the lubricating oil F to prevent rusting etc. in the compressor body 1 etc. ing.

However, the above-mentioned conventional technique requires the heater 24 and the normally-closed contact 32C of the electromagnetic switch 32 for controlling the operation of the heater 24. There is a problem that not only the working efficiency of wiring work and assembling work is lowered, but also the cost is drastically increased due to the significant complexity.

In addition, while the power is being supplied, the operator may accidentally
If the lubricating oil F is drained from No. 5, the heater 24 is exposed to the air and becomes overheated, so that the risk of ignition is increased and the safety and reliability are significantly reduced. There is.

Further, according to the prior art, the operation of the heater 24 is interlocked with the electric motor 8 and the heater 24 is not controlled based on the temperature of the lubricating oil F, so that the temperature control efficiency is low, There is a problem of low controllability.

The present invention has been made in view of the above-mentioned problems of the prior art, and effectively keeps the oil in the oil tank warm to prevent drain separation, and simplifies the overall structure to greatly improve safety and the like. An object is to provide an oil-cooled air compressor that can be improved.

[0037]

In order to solve the above-mentioned problems, the feature of the configuration adopted by the present invention is that an oil temperature detecting means for detecting the oil temperature in the oil tank is provided and the oil temperature detecting means is used. When the detected temperature is equal to or higher than the predetermined temperature, the motor is intermittently driven in the intermittent operation mode, and when the temperature detected by the oil temperature detecting means is equal to or lower than the predetermined temperature, the motor is continuously driven in the continuous operation mode. is there.

[0038]

With the above structure, when the oil temperature in the oil tank falls below a predetermined temperature, the oil temperature detecting means detects this and continuously drives the motor in the continuous operation mode. This causes the compressor body to start compression operation and generate compression heat,
This compression heat warms the oil in the oil tank.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those of the prior art shown in FIGS. 5 to 8 are designated by the same reference numerals and the description thereof will be omitted.

First, FIGS. 1 and 2 show a first embodiment of the present invention.

In the figure, reference numeral 41 denotes a starting relay applied to this embodiment in place of the starting relay 31 according to the above-mentioned conventional technique, and the starting relay 41 is almost the same as the starting relay 31 described in the conventional technique. Similarly, it has a normally open contact 41A for self-holding, and a normally open contact 41B connected in series to an electromagnetic switch 42 described later. However, in the starting relay 41 according to the present embodiment, the normally open contact 31C connected to the heater 24 described in the related art is eliminated.

Reference numeral 42 denotes an electromagnetic switch according to this embodiment,
The electromagnetic switch 42 is the electromagnetic switch 32 described in the prior art.
Almost similarly, the normally open contact 42A is provided in the middle of the power supply line 26, the normally closed contact 42B is connected in series to the pilot lamp 34, and the pressure switch 20 and the temperature switch 2 are connected.
3 is OR-connected. However, the electromagnetic switch 42 according to the present embodiment is different from that according to the related art in that the normally closed contact 32C connected in series to the temperature switch 23 described in the related art is eliminated.

Since the electromagnetic switch 42 eliminates the normally-closed contact 32C described in the prior art, the restriction of the power feeding path via the temperature switch 23 is released.
When either the pressure switch 20 or the temperature switch 23 is closed, it is excited and the normally open contact 42A is closed to rotate the electric motor 8.

The oil-cooled air compressor according to this embodiment has the above-mentioned structure, and its basic operation is not different from that of the prior art.

Therefore, in this embodiment, the pressure switch 20 and the temperature switch 23 are OR-connected to the electromagnetic switch 42, and when either of the switches 20 and 23 is closed, the electromagnetic switch 42 is supplied with power. Therefore, as shown in FIG. 2, the pressure in the discharge pipe 16 reaches the upper limit value P1, the temperature of the lubricating oil F exceeds a predetermined temperature T1, both the pressure switch 20 and the temperature switch 23 are opened, and Even when the continuous operation mode shown in A is changed to the intermittent operation mode shown in section B, as shown in sections C1 and C2 in FIG. 2, when the temperature of the lubricating oil F decreases and falls below the predetermined temperature T1, By closing the temperature switch 23, the electromagnetic switch 42 can be excited, and the electric motor 8 can be rotationally driven to generate heat of compression by the compressor body 1.

As a result, even when the continuous operation mode is switched to the intermittent operation mode, when the temperature of the lubricating oil F becomes equal to or lower than the predetermined temperature T1 due to heat radiation, the lubricating oil F
The electromagnetic switch 42 is rapidly excited on the basis of the temperature of 1 to automatically rotate the electric motor 8 to generate spot heat of compression from the compressor main body 1, so that the lubricating oil F is effectively produced by the heat of compression. Can be heated and kept warm,
The drain can be reliably separated in the lubricating oil F to prevent rusting and the like.

Since the lubricating oil F is kept warm by the compression heat generated by the spot-like operation of the compressor body 1, the heater 24 described in the prior art and the operation of the heater 24 are controlled. The normally closed contact 32C and the like can be eliminated, the overall structure can be greatly simplified, the work efficiency of wiring work and assembly work can be improved, and the cost can be greatly reduced.

Further, as a result of eliminating the heater 24, even if the lubricating oil F is drained from the oil tank 15 due to an erroneous operation, it is possible to reliably prevent the oil-cooled air compressor from igniting, so that safety and It is possible to greatly improve reliability and the like.

Furthermore, unlike the prior art, the lubricating oil F
The electric motor 8 is driven based on the temperature of the compressor main body 1
Since the temperature of the lubricating oil F is controlled by the compression heat, the temperature control efficiency and controllability are high, and the performance and reliability can be greatly improved.

Next, FIGS. 3 and 4 show a second embodiment of the present invention, which is characterized in that an electric fan interlocking with the temperature switch is provided. In this embodiment, the same components as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 51 denotes an electric fan provided near the compressor body 1. The electric fan 51 is
When either one of the temperature switch 52 and the temperature protector 53, which will be described later, exceeds a predetermined temperature, power supply is permitted and the power is operated, thereby cooling the compressor body 1 and the like.

52 is the temperature switch 23 described in the prior art.
Instead of this, a temperature switch applied to this embodiment is shown, and the temperature switch 52 is the temperature switch 2 described in the related art.
In the same manner as 3, the oil tank 15 is mounted to detect the temperature of the lubricating oil F, and is OR-connected to the electromagnetic switch 42 together with the pressure switch 20. However, the temperature switch 52 according to the present embodiment is different from that according to the related art in that it has a normally closed contact 52A and a normally open contact 52B. And
The normally closed contact 52A of the temperature switch 52 is OR-connected to the electromagnetic switch 42 together with the pressure switch 20, and the normally open contact 52B thereof is OR connected to the electric fan 51 together with the normally open contact 53B of the temperature protector 53 described later. Has been done.

Reference numeral 53 denotes a temperature protector according to this embodiment. The temperature protector 53 is provided in the vicinity of the discharge port of the compressor body 1 in the same manner as the temperature protector 28 described in the prior art. However, the temperature protector 53
It has a normally closed contact 53A and a normally open contact 53B connected to the electric fan 51.

Thus, in this embodiment having such a structure, it is possible to obtain substantially the same operational effects as those of the first embodiment described above. However, in particular, in this embodiment, the electric fan 51 is provided near the compressor body 1, and the electric fan 5 is provided.
Since the normally open contact 52B of the temperature switch 52 and the normally open contact 53B of the temperature protector 53 are OR-connected to 1, the temperature of the lubricating oil F, for example, exceeds a predetermined temperature T1 as shown in FIG. , Normally open contact 5 of temperature switch 52
When 2B is closed, or when the temperature of the air discharged from the compressor body 1 exceeds a predetermined temperature and the normally open contact 53B of the temperature protector 53 is closed, the electric fan 51 is reliably operated and the compressor is operated. The main body 1 can be effectively cooled, and it is possible to reliably prevent the galling phenomenon due to thermal expansion from occurring in each scroll or the like of the compressor main body 1, and further improve the performance and reliability. You can

In each of the above embodiments, the case where the pressure sensor 20 as the pressure detector is provided in the middle of the discharge pipe 16 has been described as an example, but the present invention is not limited to this, and for example, the oil tank 15 may be used. Alternatively, it may be provided in another discharge system, such as inside the air tank 17.

In each of the above embodiments, the case where the suction unloader 9 is provided integrally with the suction port 4 of the compressor body 1 has been described, but instead of this, the suction unloader is provided separately from the suction port 4. It may be provided.

Further, although the scroll type air compressor has been described as an example of the oil cooling type air compressor in the above embodiment, the present invention is not limited to this, and for example, a vane type compressor,
It can be widely applied to other oil-cooled air compressors such as screw compressors.

[0058]

As described above in detail, according to the present invention, the oil temperature detecting means for detecting the oil temperature in the oil tank is provided, and when the temperature detected by the oil temperature detecting means is equal to or higher than the predetermined temperature, the intermittent operation mode is set. Since the motor is intermittently driven by, when the temperature detected by the oil temperature detecting means is equal to or lower than a predetermined temperature, the motor is continuously driven in the continuous operation mode.
When the oil temperature in the oil tank drops below a certain temperature,
The oil temperature detecting means can detect this and continuously drive the motor in the continuous operation mode, and can effectively warm the oil in the oil tank by the compression heat of the compressor body.

As a result, when the temperature of the oil falls below a predetermined temperature due to heat radiation or the like, the motor is quickly and automatically rotated on the basis of the temperature of the oil to generate the compression heat in spots from the compressor body. By doing so, the oil can be effectively heated and kept warm by this compression heat, the drain can be reliably separated in the oil, and rusting and the like can be prevented.

Further, since the oil is kept warm by the compression heat generated by the spot-like operation of the compressor body, the heater and the like described in the prior art are not required, and the safety and reliability can be improved, and the entire structure can be improved. Can be simplified, the work efficiency of the wiring work and the assembling work can be improved, and the cost can be reduced.

Further, since the motor is driven based on the oil temperature and the oil temperature is controlled by the compression heat of the compressor body, the control efficiency and controllability of the temperature control are high, and the performance and reliability are high. Can be improved.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a circuit configuration of an oil-cooled air compressor according to a first embodiment of the present invention.

FIG. 2 is a time chart showing an operation state of the oil-cooled air compressor in FIG.

FIG. 3 is a circuit configuration diagram showing a circuit configuration of an oil-cooled air compressor according to a second embodiment of the present invention.

FIG. 4 is a time chart showing an operating state of the oil-cooled air compressor in FIG.

FIG. 5 is a vertical sectional view showing an oil-cooled air compressor according to a conventional technique.

FIG. 6 is an enlarged vertical sectional view showing the suction unloader in FIG.

FIG. 7 is a circuit configuration diagram showing a circuit configuration of an oil-cooled air compressor according to a conventional technique.

FIG. 8 is a time chart showing an operating state of an oil-cooled air compressor according to a conventional technique.

[Explanation of symbols]

 1 Compressor Body 4 Suction Port 8 Electric Motor 9 Suction Unloader 15 Oil Tank 20 Pressure Switch 22 Solenoid Valve 23,52 Temperature Switch (Oil Temperature Detection Means) F Lubricating Oil

Claims (1)

[Claims] 1. A compressor main body which is rotationally driven by a motor and compresses air while receiving oil supply, and a compressor main body which is provided on a suction port side of the compressor main body and shuts off intake of outside air by supply of compressed air. A suction unloader to be in an unload state, an oil tank provided on the discharge port side of the compressor body for collecting oil in compressed air discharged from the compressor body, and a discharge system including the oil tank. A pressure detector for detecting the pressure and a solenoid valve provided between the suction unloader and the discharge system to supply compressed air to the suction unloader and opened and closed according to the pressure detected by the pressure detector. And an oil-cooled air compressor configured to be capable of switching between an intermittent operation mode in which the motor is stopped in the unload state and a continuous operation mode in which the motor continues to be driven even in the unload state. The oil temperature detecting means for detecting the oil temperature in the oil tank is provided, and when the temperature detected by the oil temperature detecting means is equal to or higher than a predetermined temperature, the motor is intermittently driven in the intermittent operation mode, An oil-cooled air compressor, wherein the motor is continuously driven in the continuous operation mode when the temperature detected by the detection means is equal to or lower than a predetermined temperature.