JP2006138297A - Operation control method for screw compressor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the amount of compressed fluid to be supplied to a consumption side while lowering the temperature of the compressed fluid to be discharged without stopping a compressor. <P>SOLUTION: This operation control method for the screw compressor comprises presetting certain pressure (target pressure Pt and/or reference pressure Pv) and controlling the capacity of a compressor body 10 for discharge side pressure Pd in the compressor body 10 to correspond to the preset pressure. When a temperature Td of the compressed fluid to be discharged from the compressor body 10 is a preset temperature (a warning temperature Td1) or higher, the preset pressure is lowered by a preset value ΔP in capacity control. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an operation control method for a screw compressor. More specifically, the present invention relates to a method for controlling the operation of a compressed compressor discharged from a compressor body when the temperature of the compressed fluid discharged from the compressor body exceeds a predetermined set temperature. The present invention relates to an operation control method for a screw compressor that can prevent an increase in temperature.

  Generally, a compressor is compressed when the temperature of the compressed fluid discharged from the compressor body exceeds a predetermined upper limit temperature in order to prevent serious damage to the compressor body due to seizure or the like. An emergency stop device is provided to stop the machine.

  However, if the compressor suddenly stops when the temperature of the compressed fluid discharged from the compressor body exceeds the preset upper limit value, for example, the working machine that has been supplied with compressed fluid from this compressor The supply of compressed fluid to the consumer side suddenly stops, and the operation of the compressed air equipment stops, greatly affecting factory operations and construction work.

  In this way, in order to prevent inconvenience due to the sudden stop of the compressor when the temperature of the compressed fluid discharged from the compressor body exceeds the set upper limit value, an oil-cooled screw compressor , In the stage before the emergency stop of the compressor, it has been proposed that some maintenance can be performed on the compressor and the emergency stop can be avoided (see Patent Document 1). When the `` upper limit value '' set to a lower level than the threshold temperature at which the operation of the compressor should be urgently stopped is set in advance, when the discharge air temperature of the compressor body detected by the sensor reaches this upper limit value, The amount of discharge when the compressor operation is shifted from the normal load mode to the load reduction mode in which, for example, the rotation speed of the motor driving the compressor body is shifted to a lower rotation speed to reduce the operation load of the compressor body. Decrease There are things that you have configured so that.

Prior art document information of the present invention includes the following.
JP 2003-3981 A

  According to the operation method of the conventional oil-cooled screw compressor configured as described above, it is discharged from the compressor main body by shifting to the above-described load reduction mode in which the rotational speed of the motor is set to a low rotational speed. The temperature of the compressed fluid can be prevented from further rising, and as a result, the operation can be continued without stopping the compressor. By removing the cause of the temperature rise of the discharged compressed air, it is possible to return to normal operation again.

  However, in the case of the above-described conventional operation control, the amount of compressed air discharged from the compressor body decreases because the motor is driven at a constant low speed, for example, while operating in the load reduction mode. When the compressed air is consumed during the operation in the load reduction mode as in the operation in the normal load mode, the consumption exceeds the supply amount of the compressed air, and the required amount of compressed air is consumed. Cannot be supplied.

  Therefore, even if the compressor can be continuously operated without stopping as described above, the consumption of compressed air by the pneumatic working machine connected to the consumer side while operating in the load reduction mode. It is necessary to stop the operation or to reduce the consumption, and the work performed by the pneumatic working machine or the like is stopped or the work efficiency is lowered.

  Further, during operation in the load reduction mode, as described above, for example, the motor speed is driven at a constant low speed so that the amount of air discharged from the compressor body is reduced. For example, if the compressed air consumed on the consumer side suddenly increases, the compressed air pressure drops rapidly and the compressed air pressure drops suddenly. The operation of the compressed air equipment such as the provided air working machine is eventually stopped.

  As described above, in the conventional operation control method, switching the compressor operation to the load reduction mode is performed as an emergency evacuation until the cause of the increase in the discharge air temperature due to maintenance or the like is removed. Even during operation in this load reduction mode, the purpose is not to continuously supply the required amount of compressed air to the consuming side.

  Therefore, even if the temperature of the compressed air discharged from the compressor main body decreases due to the operation in the load reduction mode, if the cause of the increase in the discharged air temperature is not removed by performing maintenance etc. However, even if the operation of the normal load mode is resumed without removing the cause of the increase in the temperature of the compressed air without being able to supply the required amount of compressed air, the compressor is again used. The discharge air temperature of the main body rises to the upper limit value and shifts to the load reduction mode.

  Furthermore, in the load reduction mode in which the amount of air discharged from the compressor body is reduced by reducing the number of revolutions of the motor, the compressor body provided in the compressor needs to supply cooling oil into the compression working space. In the case of a so-called “oil-free compressor”, the discharge air temperature of the compressor body rises due to the decrease in the rotational speed.

  In other words, in an oil-free screw compressor that is not lubricated with oil, a small gap should be provided between the male and female screw rotors so that they do not contact each other between the inner wall of the cylinder and the rotors. An oil-cooled compressor that prevents rotation of the compressed gas due to contact between the rotors and sealing with oil because no oil is introduced to rotate and seal such fine intervals. Unlike the main body, the structure is such that the backflow of the compressed gas is likely to occur, and this is prevented by increasing the rotational speed of the screw rotor.

  However, when the rotational speed of the compressor main body is reduced as described above, the amount of compressed gas flowing back into the compression working space located on the suction side where the pressure is lower than that on the discharge side increases. Thus, the compressed fluid that has flowed back is compressed again, so that the temperature of the compressed gas discharged from the compressor body rises and the temperature of the discharged gas rises.

  As an example, such an oil-free compressor has a compressed air discharged at a rotational speed of 80% of the rated rotational speed, assuming that the temperature of the compressed air discharged at the rated rotational speed is 170 ° C. The temperature becomes 175 ° C., and the temperature rises by 5 ° C.

  Therefore, the conventional operation control method with a reduction in the number of rotations of the motor cannot be applied to the oil-free screw compressor.

  The present invention has been made in order to eliminate the various disadvantages of the above-described conventional technology. When the temperature of the compressed fluid discharged from the compressor body provided in the compressor rises, the compressor is stopped. The temperature of the compressed fluid discharged without being reduced can be reduced, and the supply amount of the compressed fluid can be ensured even in the operation state where the discharge temperature is lowered, and the compressed fluid on the consumption side can be secured. It is an object of the present invention to provide an operation control method for a screw compressor that can secure a supply amount of a compressed fluid corresponding to a change in the consumption amount, particularly an increase in the consumption amount.

In order to achieve the above object, an operation control method for a screw compressor according to the present invention includes:
A screw compression that sets a predetermined set pressure (target pressure Pt and / or reference pressure Pv) in advance and controls the capacity of the compressor body 10 so that the discharge side pressure Pd of the compressor body 10 matches the set pressure. In the operation control method of the machine,
When the temperature Td of the compressed fluid discharged from the compressor body 10 is equal to or higher than a preset temperature (warning temperature Td1), the set pressure in the capacity control is decreased by a predetermined value ΔP. Item 1).

  In the operation control method for the screw compressor described above, when the capacity control includes speed control for controlling the rotation speed of the compressor body 10 in accordance with the set pressure (target pressure Pt), the set pressure (target The pressure Pt) is decreased from the normal target pressure Pt1 (as an example, 0.7 MPa) as an example to the warning target pressure Pt2 (as an example, 0.65 MPa) that is lower than the predetermined value ΔP (as an example, 0.05 MPa). The maximum pressure of the compressor main body 10 in the speed control within the margin of the output generated in the drive source for driving the compressor main body due to the decrease in the discharge pressure of the compressor main body accompanying the decrease in the set pressure. The rotational speed Nmax can be increased (claim 2).

  Further, when the capacity control includes suction control for controlling the suction amount of the fluid to be compressed with respect to the compressor body 10 according to the set pressure (reference pressure Pv), the compressed fluid discharged from the compressor body 10 When the temperature becomes equal to or higher than the set temperature (warning temperature Td1), the set pressure may be reduced without reducing the rotational speed of the compressor body 10.

  A predetermined temperature higher than the set temperature is set as the upper limit temperature Tdmax as the upper limit value of the temperature of the compressed fluid discharged from the compressor body 10, and the temperature Td of the compressed fluid discharged from the compressor body 10 is The compressor body 10 may be stopped when the upper limit temperature Tdmax is reached (claim 4).

  Furthermore, the compressor main body 10 may be stopped when the temperature of the compressed fluid discharged from the compressor main body 10 is equal to or higher than the set temperature (warning temperature Td1) continuously for a predetermined time. ).

  In addition to the above configuration, when the discharge side pressure of the compressor main body 10 is equal to or higher than the set pressure, the compressed fluid discharged from the compressor main body 10 can be released to the atmosphere. 6).

  With the configuration of the present invention described above, when the temperature of the compressed fluid discharged from the compressor main body is equal to or higher than the set temperature, a pressure reduced by a predetermined value is applied as a reference pressure for capacity control. As a result, the discharge pressure of the compressed fluid discharged from the compressor can be lowered, the temperature of the compressed fluid discharged from the compressor body can be lowered, and the capacity control of the compressor body can be performed according to the reduced reference pressure. The compressed fluid corresponding to the change in the consumption amount of the compressed fluid on the side can be supplied, and the supply of the compressed fluid can be continued without stopping the compressor.

  Further, when the capacity control includes speed control of the compressor body, the discharge pressure of the compressor body decreases with a decrease in the reference pressure, so that the output of the drive source that drives the compressor body is reduced. By increasing the rotation speed of the compressor main body in the speed control within the range of the generated margin, the temperature of the compressed fluid discharged from the compressor main body can be lowered, and the consumption of the compressed fluid on the consumption side Even in the case where the flow rate increases, it is possible to provide an operation control method that can increase the amount of compressed fluid supplied in response to the increase.

  Further, when the capacity control includes the suction control of the compressor main body, it is possible to suppress a decrease in the supply amount of the compressed fluid by performing the capacity control without reducing the rotation speed of the compressor main body. As a result, it was possible to provide an operation control method capable of lowering the temperature of the compressed fluid discharged from the compressor body and supplying a necessary amount of compressed fluid to the consuming side.

  In addition, as described above, by increasing the rotation speed of the compressor main body or performing operation control without decreasing the rotation speed of the compressor main body, the discharge is accompanied by a decrease in the rotation speed of the compressor main body. It was possible to provide an operation control method that can be applied to an oil-free compressor in which the temperature of the compressed fluid to be increased rises.

  Next, embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1
1. FIG. 1 shows a configuration example of an oil-free compressor 1 to which an operation control method of the present invention is applied. In the illustrated embodiment, the oil-free compressor 1 is an oil-free screw type. Compressor body 10, a motor 15 that is a drive source of the compressor body 10, and an inverter 31 that converts the frequency of current from an AC power source and outputs the converted frequency to the motor 15. 10 is driven by a suction valve 21 connected to the suction port 10a of the compressor body 10 and a suction filter 34 communicated with the suction valve 21 via a suction passage 32. Outside air is introduced into the cylinder, the outside air introduced into the cylinder is compressed by the rotation of the rotor, and the obtained compressed air is discharged from the discharge port 10b of the compressor body 10. It is configured to be discharged.

  In the following embodiment described with reference to FIG. 1, the motor 15 is used as a drive source of the compressor body 10 as described above, and an inverter for controlling the rotational speed of the motor 15. The oil-free compressor provided with 31 is described as an example. However, the drive source of the compressor body 10 is not limited to the motor 15 described below, and this can be an engine. Instead of the inverter 31, for example, an electronic governor or the like that performs engine speed control may be provided.

  The compressor body 10 to be used is not limited to the oil-free type, and an oil-cooled type may be used.

  In the oil-free compressor 1 having such a basic configuration, the discharge port 10b of the compressor body 10 is communicated with an aftercooler 12 serving as a cooling means for compressed air via a discharge passage 61, and the aftercooler. 12 is connected to a supply passage 63 for introducing compressed air cooled by the aftercooler 12 to a consumption side to which an unillustrated air working machine or the like is connected.

2. Capacity control device The oil-free compressor 1 having the basic configuration as described above includes a speed control means 3 (inverter 31 in the present embodiment) for controlling the rotational speed of the compressor body 10, and a compressor. A capacity control device (2, 3, 4) comprising a suction control means 2 for controlling the amount of air sucked into the main body 10 and a control device 4 for electronically controlling the operation of the speed control means 3 and the suction control means 2. Is provided.

  In the present embodiment, the set pressure (target pressure Pt) serving as the reference for the speed control and the set pressure (reference pressure Pv) serving as the reference for the suction control are set as the set pressures when the capacity control is performed. The speed control means 3 is set separately, and the discharge side pressure Pd of the compressor main body 10 detected by the pressure detection means 50 such as a pressure sensor based on the signal from the control device 4 (this In the embodiment, the number of rotations of the motor 15 and thus the compressor main body driven by the motor 15 is set so that the pressure in the supply passage 63 matches the target pressure Pt (Pt1 or Pt2). The suction control means 2 controls the number of rotations 10 and the suction port 10 of the compressor body 10 according to the discharge side pressure Pd of the compressor body 10 according to the suction control signal from the control device 4 described above. The discharge side pressure of the compressor main body 10 is controlled by opening / closing control or opening degree control of the suction valve 21 provided in the control valve 10 or by discharging the pressure on the discharge side of the compressor main body 10. It is made to coincide with the reference pressure Pv (Pv1 or Pv2). By such speed control and intake air control, the compressor main body 10 maintains a substantially constant pressure even when the consumption amount of compressed air on the consumption side changes. The compressed air can be supplied to the consumer side.

2-1. Intake control means In the above-described intake control means 2 constituting the above-described capacity control device, the discharge side pressure Pd of the compressor body detected by the pressure detection means becomes a preset reference pressure Pv (Pv1 or Pv2). Thus, the suction amount of the compressor body and the discharge amount on the discharge side of the compressor body are controlled. In this embodiment, the suction control means 2 is communicated with the suction port 10a of the compressor body 10. The suction valve 21 opens and closes the suction passage 32 and the hydraulic cylinder 22 opens and closes the suction valve.

  In the illustrated embodiment, together with the suction valve 21, the discharge passage 35 branched from the discharge passage 61 between the discharge port 10 b of the compressor body 10 and the check valve provided upstream of the aftercooler 12. The air release valve 37 that opens and closes the air release passage 35 can be opened and closed by a hydraulic cylinder 22 that opens and closes the suction valve 21.

  The hydraulic cylinder 22 communicates with a hydraulic pump (not shown), and an open / close valve (not shown) that opens and closes a hydraulic circuit (not shown) that introduces hydraulic oil from the hydraulic pump to the hydraulic cylinder 22. A suction control signal from a control device 4 to be described later, which outputs a predetermined suction control signal according to the pressure detected by the pressure detection means 50 for detecting the discharge side pressure of the compressor body 10. In response to the opening and closing, the unloading operation in which the intake valve 21 is closed opens the release valve 37 to release the compressed air on the discharge side of the compressor body 10 and the load in which the intake valve 21 is opened. During operation, the discharge valve 37 is closed to stop the discharge of the compressed air discharged from the compressor body, whereby the discharge side pressure Pd of the compressor body is set to the set reference pressure Pv (Pv1 or Pv1). Is controlled to be Pv2).

2-2. Speed control means The speed control means 3, which is another constituent element of the capacity control device described above, receives the detection signal of the pressure detection means 50 that detects the discharge side pressure Pd of the compressor body 10, and will be described later. Receiving the target pressure signal included in the command signal from the compressor and the discharge side pressure signal of the compressor body, and compressing the compressor body so that the discharge side pressure Pd of the compressor body matches the target pressure Pt (Pt1, Pt2). The rotational speed N of the machine body 10 is controlled between an unload rotational speed Nmin which is a lower limit and a maximum rotational speed Nmax which is an upper limit.

  In this embodiment, the speed control means 3 receives a command signal from the control device 4 to be described later, and the discharge side pressure Pd of the compressor body included in the command signal is set to the target pressure Pt (Pt1 or Pt Pt2) is provided with a PI calculation circuit or a PID calculation circuit for calculating a frequency that causes rotation of the motor to be matched with Pt2), and converts the power supply frequency input from the AC power source into the calculated frequency to convert the compressor The inverter 31 is output to the motor 15 that drives the main body 10.

  Thereby, when the discharge side pressure Pd of the compressor body 10 is less than the target pressure Pt (Pt1 or Pt2) set in advance for speed control, the inverter 31 increases the rotational speed of the motor 15 to the rated rotational speed. As described above, the frequency of the drive signal output to the motor is gradually increased to increase the operating speed of the compressor body 10 to the maximum rotational speed Nmax, while the discharge pressure Pd of the compressor body 10 is set to the target pressure Pt. When (Pt1 or Pt2) is exceeded, the frequency of the drive signal output to the motor 15 is gradually decreased so that the rotational speed of the motor 15 is decreased to the unload rotational speed Nmin. Thus, speed control is performed to reduce the operating speed of the compressor body 10 to the unload speed Nmin.

  In addition, when the discharge side pressure Pd of the compressor body 10 matches the preset target pressure Pt (Pt1 or Pt2), the motor 15 is maintained so as to maintain the rotation speed of the motor 15 when the pressures match. The output frequency of the drive signal output to 15 is maintained constant without being increased or decreased.

2-3. Control Device As described above, the control device 4 that outputs various command signals for causing the suction control means 2 and the speed control means 3 to perform predetermined operations is the discharge air in the vicinity of the discharge port 10 b of the compressor body 10. Receiving the detection signals from the discharge air temperature detection means 54 for detecting the temperature of the compressor and the pressure detection means 50 for detecting the discharge side pressure of the compressor body 10, and receiving the suction control means 2 and the speed control means 3 described above. As an example, the control device 4 outputs a predetermined control signal to the control unit 4 by executing a program stored in advance in a predetermined storage area (for example, the storage unit 45 in FIG. 1). Can be configured by an electronic control device including a processing unit such as a microprocessor, and the processing unit executes the program, whereby the method of the present invention is performed. The means necessary for performing the speed control can be configured to be realized in the electronic control unit.

  In the present embodiment, as an example, the control device 4 implements a set pressure changing means 41, a command signal generating means 42, a stop signal generating means 43, and a suction control signal generating means 44, respectively. The operation control method of this invention is implement | achieved when each means performs the following operation | movement.

(1) Set pressure changing means The set pressure changing means 41 realized in the control device 4 is the discharge side of the compressor main body 10 detected by the pressure detecting means 50 when the discharge air temperature of the compressor main body 10 rises. According to the pressure Pd, the reference pressure Pv (Pv1 or Pv2) when the suction control means 2 performs the suction control and the target pressure Pt (Pt1 or Pt2) that becomes the reference when the speed control means 3 performs the speed control. The discharge air temperature Td of the compressor body 10 detected by the discharge air temperature detecting means 54 is changed, and the set temperature (hereinafter referred to as “warning temperature”) Td1 (an example) is stored in the storage means 45 in advance. When the temperature of the discharge air of the compressor body detected by the temperature detecting means 54 is lower than the warning temperature Td1, The normal target pressure Pt1 (as an example, 0.7 MPa) and the normal reference pressure Pv1 (as an example, 0.75 MPa) are applied as the aforementioned target pressure Pt and reference pressure Pv, respectively, and the detected discharge air temperature Td is When the warning temperature Td1 is exceeded, the warning target pressure Pt2 (for example, 0.65 MPa) lower than the normal target pressure Pt1 and the normal reference pressure Pv1 by a predetermined amount ΔP (for example, 0.05 MPa) and the warning time A reference pressure Pv2 (0.70 MPa as an example) is applied as the target pressure Pt and the reference pressure Pv, respectively.

  Here, the warning temperature Td1 is a temperature set lower by a predetermined value (10 ° C. as an example) than the upper limit value Tdmax (250 ° C. as an example) of the discharge air temperature at which the compressor main body can be safely operated. It is.

  In the set pressure changing means 41, after the normal target pressure Pt1 and the normal reference pressure Pv1 are changed to the target pressure Pt2 for warning and the target pressure Pt and the reference pressure Pv are once changed from the reference pressure Pv2 for warning, When the target pressure Pt2 and the warning reference pressure Pv2 are returned to the normal target pressure Pt1 and the normal reference pressure Pv1, the discharge air temperature detecting means 54 described above causes the discharge air temperature of the compressor body 10 to be changed again to the warning temperature Td1. The discharge air may be performed when it is detected that the temperature is less than or less than the return temperature Td2 (220 ° C. as an example) set to a temperature lower than the warning temperature Td1 described above. It may be performed when the temperature detecting means 54 detects it.

  In this case, the target pressure Pt and the reference pressure Pv are set to a predetermined time (about 30 seconds as an example) until the effect obtained by setting the target pressure Pt2 and the reference pressure Pv2 for warning are set to be ΔP lower, respectively. The changing unit 41 may not compare the discharge air temperature Td detected by the discharge air temperature detecting unit 54 with the warning temperature Td1 (or the return temperature Td2) again.

  Further, such a return to the normal target pressure Pt1 and the normal reference pressure Pv1 may be performed by, for example, instructing a reset (return) by operating a reset button (not shown). When the rise in the discharge air temperature of the compressor main body 10 is derived from the rise in the intake air temperature sucked into the compressor main body 10, the temperature of the intake air sucked into the compressor main body 10 is detected. When the intake air temperature detecting means (not shown) is separately provided and the intake air temperature detecting means receives the detection signal that the intake air temperature has decreased below a predetermined temperature, the set pressure changing means 41 The target pressure Pt and the reference pressure Pv may be returned to the normal target pressure Pt1 and the normal reference pressure Pv1.

  Furthermore, although illustration is omitted, when the compressor body 10 is a multi-stage compressor body composed of two stages, a high pressure stage and a low pressure stage, the discharge air temperature of the low pressure stage compressor body is detected. The first discharge air temperature detection means and the second discharge air temperature detection means for detecting the discharge air temperature of the high pressure stage compressor body are provided, respectively, and the temperature of the discharge air detected by the first discharge air temperature detection means is When the temperature exceeds the first warning temperature (200 ° C. as an example), the setting of the target pressure Pt and the reference pressure Pv is decreased by a predetermined value ΔP, and the discharge air temperature detected by the second temperature detection means is the second warning temperature. When the temperature becomes equal to or higher than (240 ° C. as an example), the setting of the target pressure Pt and the reference pressure Pv may be decreased by a predetermined value ΔP, and the pressure setting may be changed.

  In the above embodiment, when the discharge air temperature of the compressor main body becomes equal to or higher than the warning temperature Td1, both the target pressure Pt and the reference pressure Pv decrease by a predetermined value ΔP (0.05 MPa). As described above, the predetermined value ΔP for decreasing the pressure at the target pressure Pt and the reference pressure Pv does not have to be the same in both cases. For example, the predetermined value ΔP for decreasing the target pressure Pt is a predetermined value for decreasing the reference pressure Pv. It may be larger than the value.

  Further, the normal target pressure Pt1, the warning target pressure Pt2, the normal reference pressure Pv1, and the warning reference pressure Pv2 changed by the set pressure changing means 41 are stored in the storage means. Further, the normal target pressure Pt1, the normal reference pressure Pv1, and the predetermined value ΔP are stored in the storage means 45, and the discharge air temperature Td detected by the discharge air temperature detection means 54 is When the temperature is equal to or higher than the warning temperature Td1, the warning target pressure Pt2 and the warning reference pressure Pv2 may be obtained by subtracting ΔP from the normal target pressure Pt1 to the normal reference pressure Pv1.

  The reference pressure Pv is preferably set slightly higher than the target pressure Pt.

(2) Command signal generating means Among the means realized in the control device 4, the command signal generating means 42 described above is the discharge side pressure of the compressor body 10 (in the illustrated embodiment, in the supply passage 63). The detection signal from the pressure detection means 50 for detecting the pressure Pd) is received and converted into a pressure signal, and the target pressure Pt (normal target pressure Pt1 or warning) set in the set pressure changing means 41 is also obtained. Hour target pressure Pt2) is converted into a target pressure signal, and a command signal composed of this pressure signal and the target pressure signal is output to the aforementioned inverter 31 which is the speed control means 3.

(3) Suction control signal generating means The suction control signal generating means 44 of the control device 4 is configured so that the discharge side pressure (pressure Pd in the supply passage 63) of the compressor body 10 detected by the pressure detecting means 50 is set as described above. When the pressure becomes higher than the reference pressure Pv (normal reference pressure Pv1 or warning reference pressure Pv2) set by the pressure changing means 41, the intake valve 21 and the air release valve 37 provided in the intake passage 32 of the compressor body 10 are operated. The hydraulic cylinder 22 is operated to close the suction passage 32 and supply hydraulic oil to the hydraulic cylinder 22 so that compressed air between the check valve and the check valve is released to the atmosphere. When a command signal is output to a solenoid valve (not shown) provided in the oil supply pipe, and then the pressure Pd in the supply passage 63 drops below the reference pressure Pv, the intake valve 21 and the exhaust valve 37 A command signal is output to the solenoid valve (not shown) so as to open and close the suction passage 32 and stop the air release on the discharge side of the compressor body 10 by operating the hydraulic cylinder 22 that opens and closes. The control means 2 controls the discharge pressure of the compressor body 10 so as to coincide with the aforementioned reference pressure Pv (Pv1 or Pv2).

(4) Stop signal generating means Further, the stop signal generating means 43 is detected by the upper limit value Tdmax (for example, 250 ° C.) of the discharge air temperature stored in the storage means 45 and the discharge air temperature detecting means 54 described above. The detected discharge air temperature of the compressor body 10 is compared, and when the detected discharge air temperature Td of the compressor body 10 becomes equal to or higher than the upper limit temperature Tdmax, a stop signal is output to the inverter 31 to Stop supplying power from the power supply.

  The stop signal is output when the discharge air temperature detected by the discharge air temperature detection means 54 is continuously equal to or higher than the warning temperature Td1 for a predetermined time instead of the above configuration. Also good.

  Although illustration is omitted, when the compressor body 10 is a multistage compressor body composed of two stages of a high pressure stage and a low pressure stage, the low pressure stage is the same as described in the above-mentioned set pressure changing means. First discharge air temperature detection means for detecting the discharge air temperature of the compressor main body and second temperature detection means for detecting the discharge air temperature of the high pressure stage compressor main body are provided, and the first temperature detection means When the temperature of the discharge air to be detected is equal to or higher than the upper limit (210 ° C. as an example) of the discharge air temperature set for the low-pressure stage compressor body, or the discharge detected by the second temperature detection means When the air temperature becomes equal to or higher than the upper limit value (for example, 250 ° C.) of the discharge air temperature set for the high-pressure stage compressor body, the motor body is stopped and the compressor body is emergency-stopped. It may be configured.

3. Action / Effect In the compressor provided with the capacity control device configured as described above, for example, when the discharge air temperature of the compressor body 10 is lower than the warning temperature Td1 (240 ° C.), The above-mentioned set pressure changing means 41 applies the normal target pressure Pt1 (0.7 MPa) and the normal reference pressure Pv1 (0.75 MPa) as the target pressure Pt and the reference pressure Pv, respectively.

  In this way, according to the target pressure Pt (normal target pressure Pt 1) set by the set pressure changing means 41, the command signal generating means 42 of the control device 4 sends the above-mentioned to the inverter 31 that is the speed control means 3. A command signal composed of a target pressure signal obtained by signalizing the normal target pressure Pt1 and a pressure signal obtained by signalizing the discharge side pressure Pd of the compressor body 10 is output.

  The PID arithmetic circuit of the inverter 31 that has received this command signal causes the motor 15 that generates the rotational speed N of the compressor body 10 to match the discharge side pressure of the compressor body 10 with the normal target pressure Pt1 (0.7 MPa). The frequency corresponding to the rotational speed of the compressor is obtained by computation, and the inverter 31 converts the power from the power source into the frequency obtained by this computation and outputs it to the motor 15, thereby changing the rotational speed N of the compressor body. The speed control of the compressor body 10 is performed.

  On the other hand, when the discharge-side pressure Pd of the compressor main body 10 is less than the normal target pressure Pt1 (0.7 MPa), the rotation speed N of the compressor main body is increased to the maximum rotation speed Nmax within a range not exceeding the output of the motor 15. When the discharge side pressure Pd of the compressor body 10 becomes equal to or higher than the normal target pressure Pt1 (0.7 MPa), speed control is performed to reduce the rotational speed N of the compressor body to the unload rotational speed Nmin. .

  Further, even when the rotational speed N of the compressor body 10 decreases to the unload rotational speed Nmin by such speed control, the discharge side pressure Pd of the compressor body 10 rises and is detected by the pressure detection means 50. When the discharge side pressure of the compressor main body 10 becomes equal to or higher than the normal reference pressure Pv1 (0.75 MPa), a solenoid valve (not shown) is actuated by the suction control signal from the suction control signal generating means 44 of the control device 4, and the suction passage Suction control is performed in which the hydraulic cylinder 22 that operates the suction valve 21 that opens and closes the valve 32 is operated and the suction valve 21 closes the suction passage 32.

  As a result, the supply of compressed air to the consumption side stops, and the increase in the discharge side pressure Pd of the compressor body 10 stops.

  Thereafter, when the discharge side pressure Pd of the compressor main body 10 decreases below the normal reference pressure Pv1 (0.75 MPa), the solenoid valve (not shown) is switched by the suction control signal output by the suction control signal generating means 44, and the hydraulic cylinder 22 operates, the suction valve 21 opens the suction passage 32, the compressor body 10 sucks and compresses the outside air, and restarts the supply of compressed air to the consumption side.

  The hydraulic cylinder 22 that operates the intake valve 21 is also connected to an air release valve 37 that opens the discharge side of the compressor body 10 to the atmosphere. When the intake valve 21 opens the intake passage 32, the air release valve 37 is opened. Is closed and is controlled to open and close by the hydraulic cylinder 22 so that the air release valve 37 is opened when the intake valve 21 closes the intake passage 32. Therefore, the compressed air is discharged between the compressor body 10 and the check valve. The pressure in the discharge port (discharge chamber) of the compressor body is adjusted by starting or stopping the operation.

  On the other hand, when the discharge air temperature of the compressor main body 10 detected by the discharge air temperature detection means 54 becomes equal to or higher than the warning temperature Td1 (240 ° C.), the set pressure changing means 41 realized in the control device 4 is Instead of the aforementioned normal target pressure Pt1 (0.7 MPa) and normal reference pressure Pv1 (0.75 MPa) set as the target pressure Pt and the reference pressure Pv, a predetermined value ΔP (0. 05 MPa) The low warning target pressure Pt2 (0.65 MPa) and the warning reference pressure Pv2 (0.7 MPa) are set as the target pressure Pt and the reference pressure Pv, respectively.

  Thus, by changing the target pressure Pt and the reference pressure Pv to low values, the discharge-side pressure Pd of the compressor body 10 instantaneously becomes equal to or higher than the target pressure Pt (warning target pressure Pt1; 0.65 MPa). The inverter 31 that has received the command signal corresponding to the changed target pressure Pt from the command signal generating means 42 of the control device 4 reduces the rotational speed N of the compressor body 10 to the unload rotational speed Nmin.

  Further, when the discharge side pressure Pd of the compressor body 10 is increased to a reference pressure Pv (a warning reference pressure Pv2; 0.7 MPa) or more by the operation of the compressor body at the unload rotation speed Nmin. The suction control signal generating means 44 of the control device 4 outputs a suction control signal to an electromagnetic valve (not shown) so that the suction valve 21 closes the suction passage 32 and the air release valve 37 opens the air release passage 35. Then, the hydraulic cylinder 22 is operated. As a result, the amount of air taken in by the compressor body 10 is reduced, and the pressure at the discharge port (discharge chamber) of the compressor body 10 is reduced.

  Thereby, the generation of compression heat generated when the compressor main body 10 compresses air is suppressed, the discharge air temperature Td of the compressor main body 10 is lowered, and the rotor of the compressor main body 10 is damaged by being seized. Is prevented.

  Thereafter, when the discharge side pressure Pd of the compressor body 10 becomes less than the warning reference pressure Pv2 (0.70 MPa), the suction control signal generating means 44 of the control device 4 is applied to an electromagnetic valve (not shown) provided in the control circuit. In response to the operation of a solenoid valve (not shown) that receives the suction control signal, the hydraulic cylinder 22 opens the suction valve 21 and sucks air into the compressor body 10 through the suction passage 32. At the same time, the air release valve 37 closes the air release passage 35, and the introduction and compression of the outside air to the compressor body 10 are resumed and the air release is stopped.

  When the discharge side pressure Pd of the compressor body 10 becomes less than the warning target pressure Pt1 (0.65 MPa) due to consumption of compressed air on the consumption side, the rotation speed N of the compressor body 10 exceeds the output of the motor. When the discharge side pressure Pd rises above the warning target pressure Pt1 (0.65 Mpa), the compressor body speed N is reduced to the unload speed Nmin. The inverter 31 that has received the command signal from the command signal generating means 42 of the device 4 controls the speed of the compressor main body 10 by the motor 15, and sets the discharge side pressure Pd of the compressor main body 10 to the warning target pressure Pt1 (0. 65MPa).

  As described above, when the discharge air temperature Td of the compressor body 10 becomes equal to or higher than the preset warning temperature Td1 (240 ° C.), the target pressure Pt serving as the reference for speed control of the compressor body is changed to the normal target pressure Pt1 ( 0.7MPa), the warning target pressure Pt2 (0.65MPa) lower than the normal target pressure Pt1 by a predetermined value ΔP (0.05MPa) is lowered. Therefore, by switching the pressure, the discharge side pressure Pd and the compressor The pressure in the discharge chamber of the main body 10 is lowered, the compression ratio of the compressor main body 10 is lowered, the generation of compression heat generated when compressing air is suppressed, and the stop signal generating means 43 of the control device 4 generates a stop signal. The discharge air temperature can be prevented from rising above the discharge air temperature (upper limit value Tdmax), and as a result, the supply of compressed air to the consuming side can be continued without stopping the compressor. ing.

  Further, when the discharge side pressure Pd of the compressor body becomes less than the warning target pressure Pt1 (0.65 MPa), the rotation speed N of the compressor body increases to the maximum rotation speed Nmax within a range not exceeding the motor output. Therefore, even if the consumption of compressed air on the consumption side increases after such pressure switching, the discharge amount of compressed air supplied to the consumption side corresponding to the increase in compressed air Can be increased.

  In particular, since the discharge pressure of the compressor body 10 is reduced by switching the target pressure Pt to the warning target pressure Pv2 that is lower than the normal target pressure Pt by a predetermined value ΔP (0.05 MPa), the compressor body 10 The motor 15 that drives the motor has a margin in output due to the decrease in the discharge pressure.

  Therefore, it is possible to increase the number of rotations of the motor, and hence the number of rotations of the compressor main body, within a margin range generated with respect to the output of the motor 15.

  As a result, even when the compressed air consumed on the consumption side increases rapidly, the compressed air can be sufficiently supplied, and the pressure of the compressed air can be prevented from rapidly decreasing.

  In particular, in the present embodiment in which the oil-free compressor main body 10 is used as the compressor main body 10, the amount of compressed air flowing backward is increased by increasing the rotational speed of the compressor main body 10 in this way. Since the discharge air temperature Td can be decreased and the discharge air temperature Td can be lowered, the discharge air temperature Td of the compressor body can be more reliably prevented from rising above the upper limit value Tdmax, and the work can be interrupted due to the emergency stop of the compressor. It can be avoided.

  As described above, the compressor operation control method described in the related art is accompanied by a decrease in the supply amount of compressed air. Although it was not possible to cope with the sudden increase in consumption and the operation of the compressed air equipment could be stopped, the compressor main body 10 Even if the discharge of compressed air from the compressor body 10 may temporarily stop until the discharge-side pressure Pd of the engine is switched from the normal target pressure Pt1 to the warning target pressure Pt2, the target pressure Pt is switched. Since the volume control corresponding to the consumption amount of compressed air on the consumption side is performed after the operation is performed, various working machines connected to the consumption side can be used as they are.

  Further, as described above, in the conventional compressor operation control method, as the discharge air temperature of the compressor main body 10 increases, the rotation speed of the compressor main body decreases. On the other hand, when applied to a screw compressor of the type, the discharge air temperature of the compressor body is raised. For this reason, this cannot be applied to an oil-free type compressor. However, in the operation control method of the present invention, the compressor main body is not reduced without a decrease in the rotation speed of the compressor main body. Since the discharge pressure can be reduced, this can also be applied to an oil-free compressor.

[Embodiment 2]
Next, another embodiment of the present invention will be described with reference to FIG.

  In the embodiment shown in FIG. 2, a compressor to which the operation control method of the present invention is applied includes a compressor body 10, a motor 15 that drives the compressor body, a power source that supplies power to the motor, and the like. However, in the compressor of the present embodiment, the speed control of the compressor main body 10 is not performed and the suction is performed in the compressor of the present embodiment. The discharge pressure of the compressor main body 10 is controlled only by control. Therefore, unlike the compressor described in the first embodiment, an inverter for performing speed control is not provided, and the motor 15 is It is driven at a constant rotational speed by the input of constant frequency power from the power source.

  In the compressor of the first embodiment described above, the compressor main body 10 has been described as including an oil-free compressor main body. However, in the present embodiment, the compressor main body 10 includes an oil-free compressor main body. A cold compressor body is used. Therefore, on the discharge side of the compressor main body 10, a receiver tank 70 for introducing a gas-liquid mixed fluid of compressed air and cooling oil discharged from the oil-cooled compressor main body 10 to separate the gas and liquid, and this A separator 71 is provided for removing oil remaining in the compressed air that has been gas-liquid separated by the receiver tank 70 and supplying only the compressed air to the consumer side.

  However, in the configuration of the present embodiment, an oil-free compressor main body can be used as described in the first embodiment, and in this case, a receiver tank 70 provided on the discharge side of the compressor main body. The separator 71 can be omitted.

  Further, in the compressor of the first embodiment, the suction valve 21 that opens and closes the suction passage 32 as the suction control means 2 is described as being opened and closed by the hydraulic cylinder 22 that is operated by refueling from a hydraulic pump (not shown). In the suction control means 2 provided in the compressor of the present embodiment, a pressure-receiving valve-closed suction valve 21 that closes the suction passage 32 by introducing compressed air into the pressure-receiving chamber is adopted as the suction valve 21. A control passage 39 for introducing the discharge side pressure of the compressor body 10 into the pressure receiving chamber of the suction valve 21 is provided, and the control passage 39 is opened and closed according to the suction control signal from the suction control signal generating means 44 of the control device 4. And the above-described intake control means 2 is provided, and the control passage 39 between the electromagnetic valve 23 and the intake valve 21 is branched to provide the intake valve. An air discharge passage 35 ′ communicating with the suction passage 32 on the primary side is provided, and the pressure on the discharge side of the compressor body 10 is discharged through the suction filter 34 when the suction valve 21 is closed. is doing. A part of the compressed air released at this time is sucked into the compressor body 10.

  As described above, the compressor according to the present embodiment is configured not to perform speed control of the compressor main body 10, so that the capacity control of the compressor main body 10 is used as a reference for suction control. Since the control device 4 according to the first embodiment is provided with the command signal output means 42 for outputting a command signal to the inverter 31, the control device 4 according to the first embodiment is provided. Such a control signal output means 42 is not provided in the control device 4, and the set pressure changing means 41 changes only the reference pressure Pv which is a reference in the suction control. It is configured.

[Description of operation]
In the compressor 1 shown in FIG. 2 configured as described above, the storage means 45 of the control device 4 stores the upper limit value Tdmax (the discharge air temperature of the compressor main body that can safely operate the compressor main body 10. As an example, a warning temperature Td1 (105 ° C as an example) that is set to be lower than the upper limit by a predetermined temperature is stored, and the set pressure changing means 41 of the control device 4 is a discharge air temperature. When the discharge air temperature Td of the compressor body 10 detected by the detection means 54 is compared with the warning temperature Td1 (105 ° C.) stored in the storage means 45, the discharge air temperature Td is less than the warning temperature Td1. The normal reference pressure Pv1 is used as the reference pressure Pv for the suction control. When the discharge air temperature Td is equal to or higher than the warning temperature Td1, a predetermined value ΔP (as an example, with respect to the normal reference pressure Pv1) .05MPa) low, and outputs a suction control signal for suction control of the compressor body 10 vigilance at reference pressure Pv2 as reference pressure Pv, respectively.

  In the present embodiment, as the above-mentioned normal reference pressure Pv1, the start pressure of the unload operation (normal start pressure Pv1a; 0.7 MPa as an example) for closing the suction passage 32 and releasing the compressed air, The return pressure (normal return pressure Pv1b; 0.6 MPa as an example) for returning to the load operation in which the suction passage 32 of the compressor body 10 being unloaded is opened and the discharge of compressed air is stopped is different from each other. Is stored in the storage means, and the normal start where the set pressure changing means 41 is the normal reference pressure Pv1 is detected by a detection signal that the discharge air temperature detecting means 54 detects the discharge air temperature equal to or higher than the warning temperature Td1. At the time of warning when the pressure Pv1a (0.7 MPa) and the normal return pressure Pv1b (0.6 MPa) are reduced by a predetermined value ΔP (0.05 MPa as an example) stored in the storage means The reference pressure Pv2 (the warning start pressure Pv2a, the warning return pressure Pv2b) is obtained by calculation, and the warning reference pressure Pv2 (the warning start pressure Pv2a, the warning return pressure Pv2b) is obtained during the suction control. The reference pressure Pv is applied.

  The suction control signal generation means 44 of the control device 4 is applied according to the discharge side pressure Pd of the compressor body 10 detected by the pressure detection means 50 and the discharge air temperature detected by the discharge air temperature detection means 54. A suction control signal for comparing the reference pressure Pv (normal reference pressure Pv1 or warning reference pressure Pv2) and causing the electromagnetic valve 23 provided in the suction control means 2 to perform a predetermined operation. Output.

  That is, when the discharge air temperature of the compressor body 10 detected by the discharge air temperature detecting means 54 is lower than the warning temperature Td1 (105 ° C.), the normal reference pressure Pv1 ( Pv1a, Pv1b) is applied, and the suction control signal generating means 44 is configured so that the discharge side pressure of the compressor body 10 (pressure Pd in the supply passage 63 in the illustrated example) is the above-described normal start pressure Pv1a (for example, 0). 7 MPa), the suction control signal for opening the electromagnetic valve 23 is output, the compressed air is supplied to the pressure receiving chamber of the suction valve 21 through the control passage 39 to close the suction passage 32, and the discharge passage Compressed air is discharged to the atmosphere via 35 ', and the pressure in the discharge chamber of the compressor body 10 is reduced.

  On the other hand, when the discharge side pressure of the compressor body 10 (in the example shown, the pressure Pd in the supply passage 63) drops below the normal return pressure Pv1b (for example, 0.6 MPa), the compressed air to the intake valve 21 is reduced. While stopping the supply and opening the suction passage 32, the suction control signal for operating the solenoid valve 23 to output the compressed air through the discharge passage 35 'is output.

  When the discharge air temperature of the compressor main body 10 detected by the discharge air temperature detecting means 54 becomes equal to or higher than the warning temperature Td1 (105 ° C.), the set pressure changing means 41 is set to the normal start pressure Pv1a ( 0.7MPa) and the normal return pressure Pv1b (0.6MPa), the warning reference pressure Pv2 (the warning start pressure Pv2a, The warning return pressure Pv2b) is obtained by calculation, and the above-described suction control signal generation means 44 uses the warning obtained by the set pressure changing means 41 to determine the discharge side pressure Pd of the compressor body 10 detected by the pressure detection means 50. Compared with the hour reference pressure Pv2 (the warning start pressure Pv2a and the warning return pressure Pv2b), the same operation as described above is performed.

  In the above description, the storage unit 45 stores the normal reference pressure Pv1 (normal start pressure Pv1a, normal return pressure Pv1b) and a predetermined value ΔP to be subtracted from the normal reference pressure Pv1. When the detected discharge air temperature is equal to or higher than the warning temperature Td1 (105 ° C.), the set pressure changing means 41 calculates the warning reference pressure Pv2 (the warning start pressure Pv2a and the warning return pressure Pv2b) by calculation. As described above, the above-mentioned warning reference pressure Pv2 (warning start pressure Pv2a, warning return pressure Pv2b) obtained in advance is stored together with the normal reference pressure Pv1 (normal start pressure Pv1a, normal return pressure Pv1b). The preset pressure changing means 41 is stored in the storage means 45 in accordance with the discharge air temperature detected by the discharge air temperature detection means 54. During the reference pressure, or as applied to select the one corresponding to the detected temperature.

  It should be noted that the stop signal generating means 43 of the control device 4 detects the discharge air temperature detected by the discharge air temperature detecting means 54 and the upper limit value Tdmax of the discharge air temperature stored in the storage means 45 of the control device 4 (for example, 110 ° C.), and when the discharge air temperature Td becomes equal to or higher than the upper limit value Tdmax (110 ° C.), a stop signal is output to the motor (power supply to the motor is stopped). This is the same as the embodiment described with reference to FIG.

  Thus, according to the control method of the present embodiment, when the discharge air temperature Td is equal to or higher than the warning temperature Td1 (for example, 105 ° C.), the reference pressure Pv is lower than the normal reference pressure Pv1 by a predetermined value ΔP. As a result of applying the set warning reference pressure Pv2, the discharge-side pressure Pd of the compressor body 10 is changed from the reference pressure Pv2 (the warning start pressure Pv2a) of 0.65 MPa by switching the reference pressure Pv. Since the pressure becomes high, the suction valve 21 closes the suction passage 32 thereby reducing the amount of air sucked into the compressor main body 10 and discharging the compressed air to the atmosphere to discharge the compressor main body 10 with the discharge port ( The pressure in the discharge chamber decreases.

  As a result, the generation of compression heat generated when the compressor body 10 compresses air is suppressed, the discharge air temperature Td is lowered, the discharge air temperature Td becomes equal to or higher than the upper limit value Tdmax, and the compressor is brought to an emergency stop. It can be effectively prevented.

  Further, when the discharge air temperature Td is equal to or higher than the warning temperature Td1 (105 ° C.), the discharge side pressure Pd and the discharge chamber are applied by applying the warning reference pressure Pv2 set to a pressure lower than the normal reference pressure Pv1. Therefore, the compression ratio of the compressor body 10 is lowered, the generation of compression heat generated when the compressor body 10 compresses air is suppressed, and the discharge air temperature Td rises to the upper limit value Tdmax or more. This can be suitably prevented.

  Further, in this embodiment, since no inverter is provided, and therefore the speed of the compressor body is not reduced, the amount of compressed air supplied to the consumer side is not reduced, and the compression consumed on the consumer side Even when the air suddenly increases, the compressed air can be sufficiently supplied, the pressure of the compressed air can be prevented from abruptly decreasing, and it can be applied to an oil-free compressor. However, the discharge air temperature does not increase with the decrease in the rotational speed of the compressor body 10.

[Other changes]
In the first and second embodiments described above, it has been described that the compressed air is released into the atmosphere in conjunction with and motivated by the operation of the suction valve 21, but for example, means for controlling the opening and closing of the suction valve 21; In order to release the compressed air to the atmosphere after the suction passage 32 is closed by the suction valve 21 separately provided with an air release valve (for example, an electromagnetic valve) for releasing the compressed air to the atmosphere Control may be made to shift the operation timing by causing the operation to be performed by a separate means.

  Further, it is not always necessary to release the compressed air. In this case, the release valve 37 and the release passages 35 and 35 'may not be provided.

  Further, in each of the embodiments described above, the compressor body 10 is driven by the motor 15. However, as described above, this may be performed by the engine.

Operation | movement explanatory drawing of the compressor for implement | achieving the operation control method of the screw compressor of this invention. Operation | movement explanatory drawing of another compressor for implement | achieving the operation control method of the screw compressor of this invention.

Explanation of symbols

1 Compressor 10 Compressor body 10a Inlet (of compressor body)
10b Discharge port (compressor body)
12 Aftercooler 15 Motor 2 Suction control means 21 Suction valve 22 Hydraulic cylinder 23 Solenoid valve 3 Speed control means 31 Inverter 32 Suction passage 34 Suction filter 35, 35 ′ Air release passage 37 Air release valve 38 Silencer 39 Control passage 4 Control device 41 Setting Pressure changing means 42 Command signal generating means 43 Stop signal generating means 44 Suction control signal generating means 45 Storage means 50 Pressure detecting means 54 Discharge air temperature detecting means 61 Discharge passage 63 Supply passage 70 Receiver tank 71 Separator

Claims (6)

In the operation control method of the screw compressor that sets a predetermined set pressure in advance and performs capacity control of the compressor body so that the discharge side pressure of the compressor body matches the set pressure,
An operation control method for a screw compressor, wherein the set pressure in the capacity control is decreased by a predetermined value when a temperature of a compressed fluid discharged from the compressor main body is equal to or higher than a preset set temperature. The capacity control includes a speed control for controlling the rotation speed of the compressor body according to the set pressure,
When the set pressure is reduced, within the range of the output margin generated in the drive source that drives the compressor main body due to the decrease in the discharge pressure of the compressor main body accompanying the decrease in the set pressure, the speed control 2. The screw compressor operation control method according to claim 1, wherein the maximum rotational speed of the compressor body is increased. The capacity control includes a suction control for controlling a suction amount of a fluid to be compressed into the compressor body according to the set pressure;
The said set pressure is reduced, without reducing the rotation speed of the said compressor main body, when the temperature of the compressed fluid which the said compressor main body discharges becomes more than the said preset temperature. Operation control method for screw compressor.   As the upper limit value of the temperature of the compressed fluid discharged from the compressor body, a predetermined temperature higher than the set temperature is set as the upper limit temperature, and the temperature of the compressed fluid discharged from the compressor body is equal to or higher than the upper limit temperature. The operation control method of the screw compressor according to any one of claims 1 to 3, wherein the compressor main body is stopped when the screw compressor is stopped.   The screw according to any one of claims 1 to 3, wherein the compressor main body is stopped when the temperature of the compressed fluid discharged from the compressor main body is equal to or higher than the set temperature continuously for a predetermined time. Compressor operation control method. The screw compressor according to any one of claims 1 to 5, wherein when the discharge side pressure of the compressor body becomes equal to or higher than the set pressure, the compressed fluid discharged from the compressor body is released to the atmosphere. Operation control method.

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