JPH08270586A - Compressor controller - Google Patents

Abstract

PURPOSE: To prevent the breakdown, etc., of a screw following unwilling restart by controlling the restart, according to the judgment result of a judging means which judges whether the propriety of restart from the operation state just before power stoppage, in the case that the power stoppage occurs in the midst of driving a screw compressor and then current application is restarted. CONSTITUTION: In the case that the control of a compressor is operating a screw compressor 2, it stores this matter in a nonvolatile memory 25. In the case that power stoppage occurs during operation and the compressor 2 stops and then current application is restarted, CPU 20 initializes each part, and then it reads out the content of storage of the nonvolatile memory 25, and in the case that it is judged that an operation switch was turned on right before power stoppage and the compressor 2 was operating, it judges the propriety of the restart of the compressor 2 next. That is, the compressor 2 is restarted by reading the voltage of a charge and discharge circuit 27 as a power stoppage time detection means after A/D conversion 26, and comparing it with allowable voltage, and judging that the restart is possible in the case that it is higher than the allowable voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressor controller for controlling a screw compressor.

[0002]

2. Description of the Related Art Conventionally, there is a compressor control device for controlling a screw compressor. The screw compressor is a combination of a pair of rotatable screws, and a drive motor is connected to at least one of the screws. When a pair of screws are rotationally driven by this drive motor, fluids such as air are pumped by these screws.

The compressor control device for controlling the screw compressor as described above is composed of a power supply circuit and a control circuit, and supplies electric power to the drive motor of the screw compressor. Such a compressor controller is set to sequence control the power supply. That is, a relay and a timer are connected to the operation switch that starts driving the screw compressor, and once the operation switch is operated, the energized state is maintained until the stop switch is operated.

[0004]

Since the compressor controller described above controls the power supply to the screw compressor in sequence, the energized state once started is continuously maintained.

However, such a sequence-controlled compressor control device does not restart the energization of the screw compressor when the power failure occurs while the screw compressor is being driven. In this case, in order to restart the drive of the screw compressor, it is necessary to turn on the operation switch of the compressor control device again, which is not preferable because the operation is complicated.
If you do not notice the power failure, the screw compressor will remain stopped forever.

For example, if the operation switch of the compressor control device is a seesaw switch whose operating state is mechanically maintained, the energization is resumed at the same time as the end of the power failure. However, if the screw compressor whose operation is interrupted is inadvertently started, the screw may reverse due to the residual back pressure, and the screw and the drive shaft may be damaged.

That is, when a load is applied to the operation by narrowing the intake port of the screw compressor, the rotation of the screw gradually decreases when the power failure occurs, and the pressure of the air pressurized by the screw also gradually decreases. . At this time, if the time required for the air pressure to decrease is longer than the time required for the screw to stop, back pressure will act on the screw, so if the screw compressor is restarted in such a state, the screw will It is easy to damage.

[0008]

According to the first aspect of the present invention,
An electric power supply means for selectively supplying electric power supplied from the outside to the screw compressor is provided, and this power supply means is provided with a power failure end detection means for detecting the end of the power failure that has occurred in the power supplied from the outside. When the termination is detected, an operating state determination means for determining whether or not the screw compressor is operating immediately before the power failure is provided, and when the operation immediately before the power failure is determined, it is determined whether or not the screw compressor can be restarted. The determination means is provided, and the power supply control means for controlling the restart of the power supply by the power supply means is provided corresponding to the determination result of the activation possibility determination means.

According to a second aspect of the present invention, in the first aspect of the present invention, the operating state determination means stores state of presence or absence of operation of the screw compressor immediately before power failure and maintains the state without requiring electric power. When the end of the power failure is detected, the content storage means reads the stored content of the state storage means and determines the presence or absence of power supply immediately before the power failure.

According to a third aspect of the present invention, in the first aspect of the present invention, the startability determination means detects the power failure time detecting means for detecting the elapsed time of the power failure, and the detected elapsed time and the preset allowable time. And a time comparing means for determining whether or not the screw compressor can be restarted.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the startability determination means is preset with the back pressure detecting means for detecting the back pressure of the screw compressor and the detected back pressure. And a back pressure comparing unit that determines whether or not the screw compressor can be restarted by comparing with an allowable value.

[0012]

According to the first aspect of the present invention, when a power failure occurs while the power supplied from the outside by the power supply means is being supplied to the screw compressor, the power failure end detection means detects the end of the power failure. . When the end of the power failure is detected, the operating condition determination means determines whether the screw compressor is operating immediately before the power failure, and when the operation immediately before the power failure is determined, the start availability determination means determines whether the screw compressor can be restarted. To do. In response to this determination result, the power supply control means controls the restart of the power supply by the power supply means, so the screw compressor is automatically restarted only when it is driven immediately before the power failure and can be started immediately after the power failure. It

According to a second aspect of the present invention, the state storage means stores the presence or absence of the operation of the screw compressor immediately before the power failure, and when the end of the power failure is detected, the content determination means reads the stored content of the state storage means and the power failure occurs. Since the presence / absence of the power supply immediately before is determined, the operating state determination means having these means can determine the presence / absence of the operation of the screw compressor immediately before the power failure.

According to a third aspect of the present invention, the power failure time detecting means detects the elapsed time of the power failure, and the time comparing means compares the detected elapsed time with the preset allowable time. Since the restart possibility is determined, the start possibility determining means including these means can determine the restart possibility of the screw compressor to which the power was supplied immediately before the power failure.

According to a fourth aspect of the present invention, the back pressure of the screw compressor is detected by the back pressure detecting means, and the detected back pressure is compared with a preset allowable value by the back pressure comparing means. Since it is determined whether or not the compressor can be restarted, the startability determination means including these means can determine whether or not the screw compressor to which power has been supplied immediately before the power failure can be restarted.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. First, the air compression system 1 of the present embodiment is shown in FIG.
As shown in FIG. 3, the screw compressor 2 and the compressor control device 3 are included.

As shown in FIG. 3, the screw compressor 2 has a pair of screws 4 and 5, and these screws 4 and 5 are rotatably combined to form a compression portion 6. . A drive motor 8 is connected to one of the screws 4 by a belt drive mechanism 7, and the compression portion 6 is located inside a main body housing 9 that is separate from the drive motor 8.

At the intake port 10 of the main body housing 9,
An intake filter 11 is mounted, and an inlet valve 12 is provided to be openable and closable at a position where the intake filter 11 communicates with the screw 4. The inlet valve 12 has a solenoid valve 13 as a drive source.
Are connected, and the solenoid valve 13 is connected to the compressor control device 3.

At the exhaust port 14 of the main body housing 9,
In addition to the oil separator 15 and the safety valve 16, a pressure sensor 17 which is a back pressure detecting means is mounted. The pressure sensor 17 is connected to the compressor control device 3, detects the pressure generated by the screws 4 and 5, and communicates with the compressor control device 3.

As shown in FIG. 2, the compressor control device 3 includes a system frame 18 together with the screw compressor 2.
The operation panel 19 of the compressor control device 3 is located on the outer surface of the system frame 18. As shown in FIG. 1, this compressor control device 3 has a CP
The CPU 20 includes a U (Central Processing Unit) 20, and the CPU 20 includes a ROM (Read Only Memory) 21 and an RA.
M (Random Access Memory) 22, I / O (Input / Outpu
t) 23, 24, non-volatile memory 25, A / DC (Analo
g / Digital Convertor) 26 is connected. I
The screw compressor 2 and the operation panel 19 are connected to the I / O 23 and the A / D 23.
A charge / discharge circuit 27 is connected to C26.

The nonvolatile memory 25 is an EEPROM (Electrically Erasable Program) such as a flash memory.
ammable ROM) and variably stores various data relating to the operation of the screw compressor 2, but the stored data is maintained without requiring electric power. The charge / discharge circuit 27 includes a resistor 29 and a capacitor 3 connected to a power source 28.
0, which charges electric power during energization and discharges electric power during a power failure.

As shown in FIG. 4, the operation panel 19 of the compressor control device 3 is provided with various switches 31 to 34 and various display sections 35. The switches 31 to
34 is an operation mode changeover switch 31, an operation mode changeover switch 32, and an operation switch 3 for inputting an operation start.
3. A stop switch 34 for inputting an operation stop.
The display section 35 displays the remaining maintenance time, various alarms, maintenance targets, and the like.

The compressor controller 3 of this embodiment is
Power supply means, power failure end detection means, operating state determination means,
It has a startability determination means and a power supply control means.
The power supply means selectively supplies power supplied from an external commercial power source (not shown) to the drive motor 8 of the screw compressor 2 in response to the input of the operation switch 33.

More specifically, when the operation switch 33 of the operation panel 19 is input, electric power is supplied to the drive motor 8 of the screw compressor 2, so that the electric power supply means is realized here. ing. Since the power supply of the power supply means is sequence-controlled, the stop switch 34 is operated by an input or the power supplied from the external commercial power source (not shown) to the compressor control device 3 is interrupted. Continue until

The power failure end detection means detects the end of the power failure that has occurred in the power supplied from the outside to the power supply means, for example, by the fluctuation of the power supplied from the commercial power source. The operating state determining means has a state storing means and a content determining means, and determines whether or not the screw compressor 2 is operating immediately before the power failure when the end of the power failure is detected, as described in detail below. To do. Therefore, the state storage means stores the presence or absence of the operation of the screw compressor 2 immediately before the power failure and maintains it without power consumption, and the content determination means of the state storage means when the end of the power failure is detected. The stored contents are read to determine whether or not power is being supplied immediately before the power failure.

More specifically, when the operation of the screw compressor 2 is started or ended by the input operation of the operation switch 33 and the stop switch 34 as described above, the CPU 20 outputs identification data indicating them. Is stored in the non-volatile memory 25, so that the state storage means is realized here. Further, the CPU 20 reads the identification data from the non-volatile memory 25 when the power failure ends, and determines whether or not the screw compressor 2 is in operation immediately before the power failure. Therefore, the content determination means is implemented here.

The availability determining means has a power failure time detecting means and a time comparing means, and as described in detail below,
When the operation immediately before the power failure is determined, it is determined whether or not the screw compressor 2 can be restarted. Therefore, the power failure time detection means detects the elapsed time of the power failure, and the time comparison means compares the detected elapsed time with a preset allowable time to restart the screw compressor 2. Judge whether or not. Further, the power supply control means controls the restart of the power supply by the power supply means according to the determination result of the activation possibility determination means.

More specifically, while the power supply 28 is energized, the conduction of the I / O 23 is turned off by the control of the CPU 20, and the capacitor 30 of the charging / discharging circuit 27 charges the electric power. However, when a power failure occurs in the power source 28, the power charged in the capacitor 30 is discharged with time through the resistor 29. When the power supply is terminated and the power supply 28 is energized, the CPU 20
Turns on the conduction of the I / O 23 to prevent the capacitor 30 from being charged, detects the voltage of the capacitor 30 in such a state, and then turns off the conduction of the I / O 23 to charge the capacitor 30. To restart.

Then, the CPU 20 compares the detected voltage with an allowable voltage stored in advance in the ROM 21 or the like, and restarts the screw compressor 2 if the detected voltage is not lower than the allowable voltage. Therefore, the power failure time detection means, the time comparison means, and the power supply control means are realized here.

In the air compression system 1 of this embodiment having such a configuration, the compressor controller 3 drives and controls the screw compressor 2, and the screw compressor 2 sends air under pressure.

In this case, the user sets the operation mode and the operation mode by manually operating the changeover switches 31 and 32 of the operation panel 19 of the compressor control device 3, and the operation switch 33.
The start of operation is specified by. Then, C which detected this
The PU 20 starts supplying power to the screw compressor 2 according to the set mode. At this time, a relay and a timer are connected to the operation switch 33 for starting the driving of the screw compressor 2, and once the operation switch 33 is operated, the energized state is maintained until the stop switch 34 is operated.

When the operation switch 33 is manually operated in this way and the driving of the screw compressor 2 is started, the identification data indicating this is stored in the non-volatile memory 25 by the CPU 20. The nonvolatile memory 25 stores various data necessary for restarting the screw compressor 2, such as an operation mode and an operation mode that can be switched by the other changeover switches 31 and 32.

In the screw compressor 2 to which electric power is supplied as described above, the drive motor 8 rotationally drives the screws 4 and 5 of the compression section 6, and air is introduced from the intake port 10 to the exhaust port by these screws 4 and 5. Pump up to 14. At this time, the discharge pressure of the compression section 6 is detected by the pressure sensor 17 and communicated to the compressor control device 3, so that the compressor control device 3 causes the solenoid valve 13 to operate the inlet valve 12 according to the detected discharge pressure. By controlling the opening degree, the intake amount of outside air is adjusted to adjust the operation load of the screw compressor 2. As described above, when the screw compressor 2 is driven by energization, the charging / discharging circuit 27 of the compressor control device 3 is also energized and charged.

As described above, a power failure may occur while the compressor control device 3 is driving the screw compressor 2. In this case, in the air compression system 1 of the present embodiment, when the power failure ends, the compressor control device 3 determines whether or not the screw compressor 2 can be restarted, and if this is possible, the compressor control device 3 causes the screw compressor 2 to restart. To restart automatically. Therefore, the processing operation of the compressor control device 3 will be described in detail below with reference to FIG.

First, when the compressor controller 3 is driving the screw compressor 2 as described above, this is stored in the non-volatile memory 25, and the charge / discharge circuit 27 is charged. When a power failure occurs in such a state, the screw compressor 2 is stopped, and even if the power failure ends and power is started, the compressor control device 3 does not restart the power supply to the screw compressor 2 at this point.

Then, the CPU 20 of the compressor control device 3 which has detected the end of the power failure reads the contents stored in the non-volatile memory 25 after initializing the respective parts, and judges whether or not the screw compressor 2 is in operation immediately before the power failure. . When it is determined that the stop switch 34 is turned on immediately before the power failure and the screw compressor 2 is not operating, the processing operation is ended without starting the power supply. However, when it is determined that the operation switch 33 was turned on immediately before the power failure and the screw compressor 2 was operating, the screw compressor 2
Whether or not to restart can be determined.

In this case, the CPU 20 converts the voltage of the charge / discharge circuit 27 from an analog value to a digital value by the A / DC 26 and reads it, and compares the detected voltage with a preset allowable voltage. When the detected voltage is lower than this allowable voltage, it is determined that the screw compressor 2 has been stopped for more than the allowable time and cannot be restarted, and the processing operation is terminated without restarting the power supply. When the detected voltage is higher than the allowable voltage, it is determined that the screw compressor 2 can be restarted without exceeding the allowable time, and the power supply is restarted to restart the screw compressor 2.

That is, the air compression system 1 of this embodiment
The compressor control device 3 automatically restarts the screw compressor 2 when power is resumed after a power failure occurs while the screw compressor 2 is being driven by the compressor control device 3. It is not necessary to turn on the operation switch 33 of No. 3 again, and the screw compressor 2 does not remain stopped forever without noticing the power failure. Moreover, when the screw compressor 2 is automatically restarted in this way, if the elapsed time of power failure exceeds the allowable time, the screw compressor 2
Since the restart of the screw compressor is stopped, the screws 4, 5 of the screw compressor 2 are prevented from being damaged by the back pressure.

In the compressor controller 3 of this embodiment,
An example is shown in which the elapsed time of the power failure is detected by the discharge voltage of the charging / discharging circuit 27, and the restart time of the screw compressor 2 is determined by comparing the elapsed time with the allowable time. However, the present invention is not limited to the above embodiment, and for example, the startability determination means is formed by the pressure sensor 17 which is the back pressure detection means and the back pressure comparison means, and the screw compressor 2 is constituted by the pressure sensor 17. It is also possible to detect whether or not to restart the screw compressor 2 by detecting the back pressure and comparing the back pressure with a preset allowable value by the back pressure comparing means.

In this case, whether or not the screw compressor 2 can be restarted can be determined according to its back pressure, so that damage to the screws 4, 5 and the like can be reliably prevented. Moreover, the pressure sensor 17 for detecting the back pressure of the screw compressor 2
Is provided conventionally, and the pressure sensor 17
Need not be newly added and the charging / discharging circuit 27 need not be provided, so that the structure can be simplified.

Further, in the compressor controller 3 of this embodiment,
Since the non-volatile memory 25 stores the presence or absence of operation of the screw compressor 2 immediately before the power failure, the screw compressor 2 immediately before the power failure is stored.
It is possible to reliably determine the driving state of the vehicle with a simple structure. Moreover, since the non-volatile memory 25 stores and maintains the maintenance data without requiring power, maintenance of the backup power supply is not required, and the stored contents can be accurately maintained even after a long power failure.

[0042]

According to the first aspect of the present invention, the power supply means for selectively supplying the power supplied from the outside to the screw compressor is provided, and the power supply means is supplied with the power from the outside. Is installed to detect the end of the power failure, and when the end of the power failure is detected, the operating condition determination means to determine whether or not the screw compressor is operating immediately before the power failure is provided. The screw is provided with the power availability control means for controlling the restart of the power supply by the power supply means in response to the determination result of the power availability determination means. If the screw compressor can be automatically restarted if power is restored after a power failure occurs while the compressor is being driven, and the screw compressor cannot be restarted. Since abort the restart, it is possible to prevent such damage to the screw by the back pressure.

According to a second aspect of the present invention, the operating state determination means stores state information indicating whether or not the screw compressor is operating immediately before the power failure and maintains it without power consumption, and when the end of the power failure is detected. By having the content determination means for reading the stored content of the state storage means and determining the presence or absence of power supply immediately before the power failure, the operating state of the screw compressor immediately before the power failure can be reliably determined with a simple structure.

According to a third aspect of the present invention, the start possibility determination means compares the detected elapsed time with the preset allowable time by the power failure time detecting means for detecting the elapsed time of the power failure and the screw compressor. By having a time comparison means for determining whether or not the screw compressor can be restarted, whether or not the screw compressor can be restarted immediately after a power failure can be judged by a simple structure, and the screw due to the back pressure at the time of automatic restart can be determined. It is possible to prevent damage to the compressor.

According to a fourth aspect of the present invention, the startability determination means includes back pressure detection means for detecting the back pressure of the screw compressor,
By having a back pressure comparison means for comparing the detected back pressure with a preset allowable value to determine whether or not the screw compressor can be restarted, it is possible to determine whether or not the screw compressor can be restarted immediately after a power failure. The determination can be made with a simple structure, and damage to the screw compressor due to back pressure at the time of automatic restart can be prevented.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a compressor control device of the present invention.

FIG. 2 is a side view showing an air compression system having a compressor control device and a screw compressor.

FIG. 3 is a vertical sectional side view showing a screw compressor.

FIG. 4 is a front view showing an operation panel of the compressor control device.

FIG. 5 is a flowchart showing a processing operation of a compressor control device.

[Explanation of symbols]

 2 screw compressor 3 compressor control device 17 back pressure detection means 25 state storage means

Claims (4)

[Claims] 1. A power supply means for selectively supplying electric power supplied from the outside to a screw compressor, and a power failure end detection means for detecting the end of a power failure that has occurred in the power supplied from the outside to the power supply means. And an operating state determination means that determines whether or not the screw compressor is operating immediately before the power outage when the end of the power outage is detected, and whether or not the screw compressor can be restarted when the operation immediately before the power outage is determined. A compressor control device comprising: a start possibility determination unit; and a power supply control unit that controls restart of power supply by the power supply unit in response to a determination result of the start possibility determination unit. 2. An operating state judging means stores a state storing means for storing the presence or absence of the operation of the screw compressor immediately before a power failure and maintaining it without power consumption, and a memory of the state storing means when the end of the power failure is detected. The compressor control device according to claim 1, further comprising: a content determination unit that reads out the content and determines whether or not power is supplied immediately before a power failure. 3. The start possibility determination means compares the detected elapsed time with a preset allowable time to determine whether or not the screw compressor can be restarted by detecting a power failure time detecting means for detecting the elapsed time of the power failure. The compressor control device according to claim 1, further comprising: a time comparison unit for making a determination. 4. The start possibility determination means compares the detected back pressure with a back pressure detection means for detecting the back pressure of the screw compressor, and restarts the screw compressor by comparing the detected back pressure with a preset allowable value. 2. The compressor control device according to claim 1, further comprising back pressure comparing means for determining whether or not it is possible.