JP7254498B2 - compressor - Google Patents

Description

The present invention relates to a compressor that compresses and discharges gas.

2. Description of the Related Art Compressors are known that take in gas such as air and discharge high-pressure gas such as compressed air using a compression mechanism. In particular, air compression is used in factory lines and work sites as an air source for machine tools, press machines, air blowers, and the like.

In order to maintain the compressor pressure at a predetermined value, this compressor has an intermittent operation control mode that stops the electric motor when the tank pressure reaches the upper limit, and an intermittent operation control mode that disables the compressor without stopping the electric motor. A continuous operation control mode is known which provides a load condition.

There is Patent Document 1 as a background art related to this technical field. Patent Document 1 includes a compressor body that compresses air, a tank that stores the air compressed by the compressor body, and a control unit that controls the driving of the compressor body. An air compressor is disclosed that controls a compressor main body so that an operation cycle time from stop to start to stop is equal to or longer than a predetermined time.

JP 2017-190781 A

In the air compressor in Patent Document 1, the upper limit of the tank pressure, which is the reference for stopping the compressor, is determined by setting the operation cycle time to be equal to or longer than a predetermined time, so the amount of air consumption increases rapidly. If the pressure increases to 200 MPa, continuous operation at high pressure may continue for a long time, causing the temperature of the compressor body to rise due to the heat of compression, making it impossible to ensure the lubrication life of sliding parts such as grease-filled bearings. , is not considered.

In view of the above problems, it is an object of the present invention to provide a compressor that can prevent the temperature rise of the compressor body due to heat of compression and that can ensure the life of the electric motor and electronic parts while being low in cost. aim.

An example of the present invention is a compressor comprising a compressor body for compressing gas, a tank for storing the gas compressed by the compressor body, and a control unit for controlling the driving of the compressor body. When the continuous load operation time of the compressor main body reaches a predetermined time T1, the control unit stops the operation or puts the compressor into an unloaded state.

Advantageous Effects of Invention According to the present invention, it is possible to provide a compressor capable of securing the service life of an electric motor and electronic parts while preventing the temperature rise of the compressor body due to heat of compression while being low in cost.

1 is an overall cross-sectional view of a compressor in Example 1. FIG. FIG. 4 is an explanatory diagram showing an unloaded state in Embodiment 1; 4 is a wiring diagram of the main parts in Example 1. FIG. 4 is an operation explanatory diagram of operation control in Embodiment 1. FIG. FIG. 10 is an operation explanatory diagram of operation control for explaining a problem in the second embodiment; FIG. 10 is an operation explanatory diagram of operation control in Embodiment 2; FIG. 11 is an operation explanatory diagram of operation control in Example 3; FIG. 5 is an operation explanatory diagram of a conventional intermittent operation control method; FIG. 5 is an operation explanatory diagram of a conventional continuous operation control method; 4 is a graph showing the relationship between pressure ratio and compression temperature in an air compressor.

Hereinafter, embodiments of the present invention will be described based on the drawings.

First, the conventional compressor operation control method, which is the premise of the present embodiment, will be described. Conventional compressor operation control methods include an intermittent operation control method and a continuous operation control method. An air compressor that compresses air as a gas will be described with reference to FIGS.

The intermittent operation control method shown in FIG. 8 is a control method in which when the tank pressure reaches the upper limit pressure, the pressure switch is turned OFF to stop the electric motor, and when the tank pressure reaches the lower limit pressure, the pressure switch is turned ON and the electric motor is started. be. This system stops the motor when the pressure in the tank reaches the upper limit pressure, so no power is wasted. However, since the motor is restarted at the lower limit pressure, if the motor is repeatedly started and stopped, the motor tends to overheat and the life of the electric parts is shortened.

In the continuous operation control method shown in FIG. 9, when the tank pressure reaches the upper limit pressure, for example, the suction valve is opened to reduce the load on the motor and perform unloaded operation, and when the pressure reaches the lower limit pressure, the suction valve is closed to return to normal load operation. With this method, even if the pressure in the tank reaches the upper limit pressure, the load is reduced by opening the air valve without stopping the electric motor. ing. However, since the motor is in unloaded operation, the load on the motor and electrical parts is lightened. It is possible to cool the machine body.

Therefore, in the air compressor, in order to suppress the temperature rise of the main body of the compressor, as the continuous operation control method described above, cooling is performed with a pulley fan in a no-load state as much as possible, and the upper limit of the control pressure is low. is as effective as This is because, as shown in FIG. 10, the temperature of the air after compression rises exponentially in proportion to the ratio of the discharge pressure Pd and the suction pressure Ps of the compressor.

Therefore, in this embodiment, operation control is performed according to the continuous load operation time of the compressor to reduce the temperature of the main body of the compressor.

FIG. 1 is an overall sectional view of a compressor in this embodiment. FIG. 1 shows the overall configuration of a reciprocating compressor, taking as an example an air compressor that compresses air as a gas.

In FIG. 1, air compressed in a compressor main body 2 for sucking and compressing air is stored in a tank 1 . A cylinder head 15 is assembled to the compressor main body 2, and the suction valve 12 and the unloader piston 13 shown in FIG. An unloader pipe 4 having a three-way solenoid valve 3 is provided between the tank 1 and the compressor body 2 .

A load state and an unload state will be described with reference to FIG. In FIG. 2, by energizing the three-way solenoid valve 3, the pressure in the tank 1 is applied to the unloader piston 13 that operates the suction valve 12 of the compressor body 2, forcibly unloading (see FIG. 2). Open the suction valve 12). As a result, even when the compressor body 2 is started, the intake valve 12 is open, so the air compressed by the compressor body 2 is not stored in the tank 1 and is released to the atmosphere from the air intake port 16. .

On the other hand, by de-energizing the three-way solenoid valve 3, the unloader piston 13 is put into a state where no pressure is applied (loaded state), and the suction valve 12 is caused to perform normal opening and closing operations. As a result, when the compressor main body 2 is started in the loaded state, the intake valve 12 is opened to take in air from the air intake port 16 , and the intake valve 12 is closed to store the compressed air in the tank 1 after compression. be.

FIG. 3 shows a wiring diagram of the main parts in this embodiment. In FIG. 3 , the electromagnetic contactor 5 is connected to a control board 6 as a control section together with the three-way solenoid valve 3 and controlled by the control board 6 together with the three-way solenoid valve 3 . The control board 6 detects the pressure of the tank 1 with the pressure sensor 11, and controls the operation and stop of the electric motor 9 by sending a signal for operating the electromagnetic contactor 5 from the electronic circuit. Further, the control board 6 operates the unloader piston 13 by sending a signal to the three-way electromagnetic valve 3, thereby controlling the unloading state and the loading state. A display 7 is mounted on the control board 6 to display the set pressure and the like.

The contents of control of the compressor by the control board 6 as the control section in this embodiment will be described with reference to FIGS.

When the operation switch 8 is not operated, the power source 17 of the electric motor 9 is cut off, so the compressor is stopped. The pressure in the tank 1 is the atmospheric pressure or the pressure of the air remaining in the tank 1, and when the three-way solenoid valve 3 is not energized, the unloader pipe 4 is in the atmospheric pressure state and is released from the unloaded state. The intake valve 12 is in a loaded state (a state in which compression operation can be performed).

When the operation switch 8 is pressed, a signal from the control board 6 activates the electromagnetic contactor 5 to close the contact 10 and start the electric motor 9 . When the electric motor 9 is started, the compressor main body 2 is operated and the pressure in the tank 1 is increased. When the pressure reaches a predetermined stop pressure Poff (arbitrarily set) and is detected by the pressure sensor 11, this detection signal is input to the control board 6, and the signal from the control board 6 causes the electromagnetic contactor 5 to operate. The power is cut off, the electric motor 9 stops, and the compressor main body 2 also stops.

After the compressor main body 2 stops, air is consumed by the operation of the customer's equipment connected to the stop valve 14, and the pressure in the tank 1 decreases. When the pressure in the tank 1 falls below a predetermined reference pressure (return pressure Pon) and is detected by the pressure sensor 11, a signal from the control board 6 energizes the electromagnetic contactor 5 to close the contact, and the electric motor 9 is restarted. It starts up and the compressor main body 2 resumes its operation.

In the intermittent operation control method, operation/stop of the compressor body 2 is controlled by such control. Here, in this embodiment, in addition to the above-described intermittent operation control, continuous operation control for controlling the load state/unload state is performed.

Regardless of the operation control method, the load operation time Tload of the compressor body 2 (the time from when the compressor body 2 is started until it is stopped) is the ratio of the amount of air used (the amount of air Air volume ratio) is longer. This is because when the amount of air used is large, the pressure in the tank 1 is difficult to rise, and the time during which the compressor body 2 is in operation is long, and when the amount of air used is small, the pressure in the tank 1 is difficult to decrease. , the time during which the compressor main body 2 is stopped becomes longer.

When the load operation time Tload is long, the temperature of the compressor body 2 rises due to heat of compression, and thermal deterioration of the bearing-filled grease and the like progresses.

Therefore, in this embodiment, when the pressure P in the tank 1 is higher than the predetermined reference pressure (recovery pressure Pon) (recovery pressure Pon+ΔP), the load operation time T of the compressor body 2 exceeds the predetermined time T1. When the time elapses, the operation is forcibly stopped. This operation prevents continuous load operation for a long period of time in a state where the operating pressure is high, and makes it possible to prevent the temperature rise of the compressor main body 2 .

The control and the temperature state of the compressor body 2 in this embodiment will be described in detail with reference to FIG.

In FIG. 4, the upper part shows the pressure change in the tank 1, the middle part shows the operating state of the compressor, and the lower part shows the body temperature of the compressor. First, after the compressor body 2 starts operating, the pressure in the tank 1 rises.

When the pressure reaches a predetermined reference pressure (recovery pressure Pon+ΔP) or higher, the timer 21 (not shown) in the control board 6 starts measuring the load operation time Tload while the motor 9 continues to operate.

When the timer 21 reaches the permissible continuous load operating time T1 (predetermined operating time for reaching the upper limit temperature for ensuring the service life of thermally degraded parts such as bearing grease, not shown), the pressure P in the tank 1 is reached. does not reach the stop pressure Poff, the motor 9 is stopped and the operation of the compressor main body 2 is stopped.

After the stop, air is consumed by the operation of the customer's equipment connected to the stop valve 14, and when the pressure in the tank 1 falls below the return pressure Pon and is detected by the pressure sensor 11, the electric motor 9 is restarted to The machine body 2 resumes operation. Here, the measurement of the timer 21 is reset, the measurement of the load operation time T is resumed, and the same control is repeated.

If the pressure in the tank 1 exceeds the stop pressure Poff before the allowable continuous load operation time T1 is reached after the start of measurement of the load operation time T, and the pressure sensor 11 detects Then, the electric motor 9 stops, and the compressor body 2 stops operating.

By the above operation, continuous load operation for a long period of time in a state of high operating pressure can be prevented, and temperature rise of the compressor main body 2 can be prevented. Therefore, it is possible to prevent heat deterioration of the grease enclosed in the bearing and extend the life of the grease.

This embodiment prevents the temperature rise of the compressor main body 2, but does not use means for measuring the temperature itself. Based on the operation time predetermined as the time to reach the point, the control of operation and stop is performed. Therefore, it is possible to reduce the manufacturing cost of the product.

As described above, according to the present embodiment, it is possible to provide a compressor capable of securing the service life of the electric motor and electronic parts while preventing the temperature rise of the compressor body due to the heat of compression, while keeping the cost low. Become.

In this embodiment, the case where the pressure drop speed after stopping the operation of the compressor body is fast will be described.

FIG. 5 is an operation explanatory diagram of operation control for explaining problems in the present embodiment. FIG. 5 shows the same pressure, operating conditions, and temperature changes as in FIG.

As shown in FIG. 5, such as when the used air volume ratio is high or when the volume of the tank 1 is small, the pressure drop rate after stopping the operation of the compressor body 2 is too fast. Since the pressure in 1 falls below the return pressure Pon in a short period of time, there is a possibility that the service life of the electric motor 9 and other electronic parts will be shortened due to excessive start/stop. In addition, since the stop time of the compressor body 2 is short, the temperature of each part of the compressor body 2 does not drop sufficiently by cooling by natural heat dissipation, and the temperature rises due to the restart after reaching the return pressure Pon, and the temperature is the same thereafter. As the operation is repeated, heat is accumulated in a stepwise fashion, and there is a possibility that the temperature of heat-degrading parts such as the bearing-filled grease may exceed the temperature at which the service life can be secured.

Therefore, in this embodiment, when the pressure P in the tank 1 is equal to or higher than a predetermined reference pressure (recovery pressure Pon+ΔP) and the load operating time Tload of the compressor body 2 is equal to or longer than a predetermined time T1, the operation is forced to start. Switch to the unload state instead of stopping.

Details of the control in this embodiment will be described with reference to FIG. It should be noted that FIG. 6 shows the same pressure, operating state, and temperature changes as in FIG.

In FIG. 6, first, after the compressor body 2 starts operating, the pressure in the tank 1 increases. When the pressure reaches the predetermined return pressure Pon+ΔP, the timer 21 (not shown) in the control board 6 starts measuring the load operation time Tload while the motor 9 continues to operate.

When the timer 21 reaches the permissible continuous load operation time T1 (predetermined operation time as the time required for heat-deteriorating parts such as bearing grease to reach the upper limit temperature to ensure the life span: not shown), the stop pressure Poff is reached. To switch the operation of a compressor body 2 to an unloaded state even if the compressor body 2 is not loaded.

After switching to the unloaded state, air is consumed by the operation of the customer's equipment connected to the stop valve 14, and the pressure in the tank 1 falls below the return pressure Pon. Switch the operation of 2 to the load state. Here, the measurement of the timer 21 is reset, the measurement of the load operation time Tload is restarted, and the same control is repeated.

If the pressure in the tank 1 exceeds the stop pressure Poff before the allowable continuous load operation time T1 is reached after the start of measurement of the load operation time T, and the pressure sensor 11 detects , the operation of the compressor main body 2 is switched to the unloaded state.

In addition, after the operation of the compressor body 2 is switched to the unloaded state, air is not consumed, the pressure in the tank 1 does not fall below the return pressure Pon, and the fixed time T2 (the compressor body 2 can be sufficiently cooled) When a predetermined operating time (not shown) elapses, the electric motor 9 is stopped and the operation of the compressor main body 2 is stopped.

The above operation prevents continuous load operation for a long period of time in a state where the operating pressure is high. Efficient cooling can prevent temperature rise. Furthermore, it is possible to prevent the life of the electric motor 9 and other electronic components from being shortened due to over-frequent starting and stopping.

Further, after the temperature of the compressor body 2 is sufficiently cooled by the operation in the unloaded state, the operation can be stopped to suppress wasteful power consumption.

In this embodiment, the case where the pressure drop rate after the operation of the compressor main body is set to the unloaded state is very slow will be described.

That is, when the air volume ratio is low, the pressure drop after the operation of the compressor main body 2 is unloaded is very slow, and the time it takes for the pressure in the tank 1 to fall below the return pressure Pon is very long. Even though sufficient time can be secured for the natural heat dissipation of the compressor main body 2 when it becomes long, if switching to the unloaded state is performed according to the second embodiment, there is a problem that power is wasted. .

Therefore, in this embodiment, only when the previous unload/stop time Tstop, which is the sum of the previous unload operation time and the stop time, is equal to or less than the predetermined time T3, the pressure P of the tank 1 is set to the predetermined reference pressure ( is equal to or higher than the return pressure Pon+.DELTA.P) and the load operation time T of the compressor body 2 has passed the predetermined time T1, the switching to the unloaded state is performed in the same manner as in the second embodiment. Similarly, the operation is forcibly stopped.

Details of the control in this embodiment will be described with reference to FIG. It should be noted that FIG. 7 shows the same pressure, operating state, and temperature changes as in FIG.

In FIG. 7, when the operation of the compressor body 2 is stopped or switched to an unloaded state, a timer 22 (not shown) in the control board 6 starts measuring the unload/stop time Tstop.

After the start of measurement of the unload/stop time Tstop, air is consumed by the operation of the customer's equipment connected to the stop valve 14, the pressure in the tank 1 falls below the return pressure Pon, and the pressure sensor 11 detects , the operation of the compressor body 2 is switched to the load state.

Here, if the unload/stop time Tstop is equal to or longer than the predetermined time T3, the next cycle (when Tload>T1 next) performs the same control as in the first embodiment, and resets the measurement of the timer 22 . Further, if the unload/stop time Tstop is equal to or less than the predetermined time T3, the control similar to that of the second embodiment is performed in the next cycle, and the measurement of the timer 22 is reset.

In this embodiment, an example will be described in which T1 during the above operation may be changed according to the previous stop time Tstop.

That is, when the previous unload/stop time is long, the compressor body 2 is sufficiently cooled, so the allowable continuous load operation time T1 can be lengthened. As a result, it is possible to prevent the life of the electric motor 9 and other electronic components from being shortened due to over-frequent starting and stopping.

Further, the determination of which of the control methods of the first embodiment and the second embodiment should be taken, or what the allowable continuous load operation time T1 should be, is determined by the unload/stop time Tstop shown in this embodiment. Alternatively, the ratio of the previous load operation time and the previous unload/stop time (ratio of air used in the previous operation cycle) may be used, or the average of several operation/stop cycles may be taken. .

Although the embodiments have been described above, each of these embodiments merely shows an example of implementation for carrying out the present invention, and the technical scope of the present invention is not limitedly interpreted by these. . That is, the present invention can be embodied in various forms without departing from its technical concept or main features. For example, in the above embodiment, a reciprocating compressor was used as the compressor, but the compressor is not limited to this. It may be a booster compressor or the like. Also, although the gas to be compressed has been described as air, it is not limited to this, and nitrogen or the like may be used.

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. Further, the above control unit may be realized by software by a processor interpreting and executing a program for realizing each function, or may be realized by hardware by designing an integrated circuit, for example.

1: tank, 2: compressor body, 3: 3-way solenoid valve, 4: unloader piping, 5: electromagnetic contactor, 6: control board, 7: display, 8: operation switch, 9: electric motor, 10: contact, 11: pressure sensor, 12: intake valve, 13: unloader piston, 14: stop valve, 15: cylinder head, 16: air intake, 17: power supply

Claims (5)

a compressor body for compressing gas;
a tank for storing the gas compressed by the compressor main body;
a fan that cools the compressor body by operating the compressor body;
A control unit for controlling the driving of the compressor body,
When the continuous load operation time of the compressor main body reaches a predetermined time T1, the control unit stops the operation or puts the compressor into an unloaded state,
When the time during which the compressor main body was previously stopped or operated in an unloaded state reached a predetermined time T3, the operation is resumed after the continuous load operation time of the compressor main body reaches a predetermined time T1. stop and
If the time during which the compressor main body was previously stopped or operated in the unloaded state did not reach the predetermined time T3, the continuous load operation time of the compressor main body reaches the predetermined time T1, and then the compressor is operated. is placed in an unloaded state , and the compressor body is cooled by the fan during operation in the unloaded state . A compressor according to claim 1,
The compressor, wherein the control unit stops the operation when the operation in the unloaded state reaches a predetermined time T2. A compressor according to claim 1 or 2,
The tank has pressure detection means for detecting internal pressure,
The compressor, wherein the control unit starts measuring the continuous load operation time when the pressure in the tank is equal to or higher than a predetermined reference pressure. A compressor according to any one of claims 1 to 3,
The control unit changes a predetermined time T1 for continuous load operation of the compressor body according to the time during which the compressor body was previously stopped or operated in an unloaded state. machine. a compressor body for compressing gas;
a tank for storing the gas compressed by the compressor main body;
A control unit for controlling the driving of the compressor body,
When the continuous load operation time of the compressor main body reaches a predetermined time T1, the control unit stops the operation or puts the compressor into an unloaded state,
When the time during which the compressor main body was previously stopped or operated in an unloaded state reached a predetermined time T3, the operation is resumed after the continuous load operation time of the compressor main body reaches a predetermined time T1. stop and
If the time during which the compressor main body was previously stopped or operated in the unloaded state did not reach the predetermined time T3, the continuous load operation time of the compressor main body reaches the predetermined time T1, and then the compressor is operated. to the unloaded state,
A compressor characterized in that a predetermined time T1 for continuous load operation of said compressor body is changed according to a time period during which said compressor body was previously stopped or operated in an unloaded state.

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