JP2015048816A - Compressor and its pressure control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compressor and its control method capable of executing an energy-saving operation while suppressing pressure rise in a load operation by shortening an operation cycle.SOLUTION: A compressor includes a suction flow channel 2, an intake regulation valve 4 maintained after the lapse of a prescribed operation period, maintenance time measuring means 11, means 13 for measuring number of times of operation, load operation time measuring means 12, and control means 18 for switching ON and OFF the intake regulation valve 4. The control means 18 switches a load operation to an unload operation, when a duration time from start of the load operation measured by the load operation time measuring means 12 during the load operation under a discharge pressure higher than a necessary minimum pressure necessary at a discharge side, is over an unloadable shortest time determined on the basis of a remaining time to the maintenance of the intake regulation valve 4, the number of times of allowable operation of the intake regulation valve 4, and the accumulated number of times of operation of the intake regulation valve 4.

Description

  The present invention relates to a compressor having an intake adjustment valve and a pressure control method thereof.

  Conventionally, the pressure of the discharge flow path, that is, the discharge pressure is kept above the required minimum pressure required on the load side by opening / closing the intake control valve provided in the suction flow path, and the discharge pressure is required. Compressors that perform energy saving operation by not increasing the height above are known. In this compressor, when the discharge pressure becomes equal to or higher than the upper limit set pressure, the intake control valve is turned off (closed), the supply of intake gas to the compressor is stopped, and the unload operation state is set. On the other hand, when the discharge pressure falls below the lower limit set pressure, the intake pressure control valve is turned on (opened) to bring the intake air to the maximum state and the load operation state. To keep the value.

  As a compressor using the above-described principle, for example, in Patent Document 1, when the discharge pressure is maintained between the lower limit set pressure and the upper limit set pressure, the load operation state or unloading is performed until a predetermined set time elapses. A compressor is described that maintains any of the load operating conditions. This compressor enables energy-saving operation without frequently repeating ON / OFF of the intake control valve.

  However, in the above compressor, since the operating state is fixed for a predetermined set time focusing on the time of time and pressure in order to reduce the power consumption, the number of times of performing the load operation can be suppressed to less than the allowable number. ing. Therefore, there remains room for further energy saving by increasing the number of times of performing the road operation and suppressing the pressure increase during the road operation.

  In Patent Document 2, the flow rate consumed in one cycle consisting of full load operation and no load operation is calculated from the full load operation time and the no load operation time, and an upper limit pressure is set according to the amount of use of the consumed flow rate. A compressor that automatically adjusts the value and the lower limit pressure setpoint is described.

  However, in the above compressor, the upper limit pressure set value and the lower limit pressure set value are operated by calculation, but any set value changes at a pressure higher than the necessary minimum lower limit pressure (Plim shown in FIG. 4 of Patent Document 2). I am letting. Therefore, since the operation is performed at a pressure higher than the conventionally known lower limit pressure value and the operation is based on a certain amount of pressure increase operation, more power is required than necessary.

  On the other hand, in the operation of the compressor, the area shown by the oblique lines in FIG. 5 (the integrated value of the discharge pressure during the operation time) corresponds to the power consumption, and it is known that the energy saving operation is achieved by reducing this area. . According to this, useless boosting operation results in a loss of power consumption. Therefore, in order to reduce the area, it is necessary to perform a control in which each operation cycle composed of the load time and the unload time is shortened to suppress the pressure increase during the load operation.

Japanese Patent No. 3607042 JP 2012-2156 A

  An object of the present invention is to provide a compressor capable of performing an energy saving operation by shortening an operation cycle and suppressing a pressure increase during a road operation, and a pressure control method thereof.

The compressor of the present invention is
A compressor body having a suction port for sucking gas, and a discharge port for discharging compressed gas sucked from the suction port;
A suction flow path for sucking gas from the outside to the suction port of the compressor body;
When turned on, the suction passage is opened and the compressor body is loaded, and when turned off, the suction passage is closed and the compressor body is unloaded, after a predetermined operation period has elapsed. An intake adjustment valve to be maintained;
Maintenance time measuring means for measuring the remaining time until maintenance of the intake regulating valve;
An operation frequency measuring means for measuring the cumulative operation frequency of the intake regulating valve;
Road operation time measuring means for measuring the duration from the start of the latest road operation;
Control means for switching between load operation and unload operation by turning on or off the intake adjustment valve;
With
The control means is in a load operation at a discharge pressure larger than the required minimum pressure required on the discharge side, and the duration from the start of the load operation measured by the load operation time measurement means is until the maintenance of the intake adjustment valve. When the minimum unloadable time determined based on the remaining time, the allowable number of operations of the intake adjustment valve, and the cumulative number of operations of the intake adjustment valve is exceeded, the operation is switched to the unload operation.

  When the minimum unloadable time is exceeded, the compressor is switched from load operation to unload operation. The shortest unloadable time is determined based on the remaining time until maintenance of the intake valve, the allowable number of operations, and the cumulative number of operations. As a result, the intake adjustment valve is operated up to the maximum allowable number of operations, and the intake adjustment valve is controlled in the shortest possible cycle, thereby making it possible to perform the energy saving operation while suppressing the pressure increase during the road operation to be small.

As one specific means, for example,
The minimum unloadable time T _U (unit: second (s)) is defined by the following equation (1).
<Equation 1>
_{T U = Tm ÷ (N1 MAX} -N1 ON) (1)
Tm: Remaining time until maintenance of intake control valve (s)
N1 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on N1 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on

As other means, for example,
The minimum unloadable time T _U (s) is defined by the following equation (2).
<Equation 2>
T _U = Tm ÷ (N2 _MAX− N2 _ON ) × 2 (2)
Tm: Remaining time until maintenance of intake control valve (s)
N2 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on and off N2 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on and off

The pressure control method of the compressor of the present invention is
A compressor body having a suction port for sucking gas, and a discharge port for discharging compressed gas sucked from the suction port;
A suction flow path for sucking gas from the outside to the suction port of the compressor body;
When turned on, the suction passage is opened and the compressor body is loaded, and when turned off, the suction passage is closed and the compressor body is unloaded, after a predetermined operation period has elapsed. An intake adjustment valve to be maintained;
A pressure control method for a compressor comprising:
Measure the remaining time until maintenance of the intake valve,
Measure the cumulative number of operations of the intake control valve,
Measure the duration from the start of the most recent road operation,
During road operation at a discharge pressure larger than the required minimum pressure required on the discharge side, the duration from the start of the most recent road operation is the remaining time until the maintenance of the intake adjustment valve and the allowable number of operations of the intake adjustment valve. When the minimum unloadable time determined based on the cumulative number of operations of the intake valve is exceeded, the operation is switched to the unload operation.

  When the minimum unloadable time is exceeded, the compressor is switched from load operation to unload operation. The shortest unloadable time is determined based on the remaining time until maintenance of the intake valve, the allowable number of operations, and the cumulative number of operations. As a result, the intake adjustment valve is operated up to the maximum allowable number of operations, and the intake adjustment valve is controlled in the shortest possible cycle, thereby making it possible to perform the energy saving operation while suppressing the pressure increase during the road operation to be small.

As one specific means, for example,
The minimum unloadable time T _U (s) is defined by the following equation (1).
<Equation 1>
_{T U = Tm ÷ (N1 MAX} -N1 ON) (1)
Tm: Remaining time until maintenance of intake control valve (s)
N1 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on N1 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on

As other means, for example,
The minimum unloadable time T _U (s) is defined by the following equation (2).
<Equation 2>
T _U = Tm ÷ (N2 _MAX− N2 _ON ) × 2 (2)
Tm: Remaining time until maintenance of intake control valve (s)
N2 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on and off N2 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on and off

  According to the present invention, it is possible to perform an energy saving operation by shortening the operation cycle by operating the intake adjustment valve to the maximum of the allowable number of operations and suppressing the pressure increase during the load operation.

Schematic of the compressor which concerns on embodiment of this invention. The flowchart which shows the compression control method which concerns on 1st Embodiment of this invention. The graph which shows the discharge pressure with respect to the operation time of the compressor of this invention and the conventional compressor. The flowchart which shows the compression control method which concerns on 2nd Embodiment of this invention. The graph which shows the discharge pressure with respect to the operation time of the conventional compressor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a compressor according to an embodiment of the present invention. The compressor 10 is, for example, a screw compressor, and includes a compressor main body 1 having a suction port 10a for sucking gas and a discharge port 10b for discharging compressed gas sucked from the suction port 10a. The compressor main body 1 includes a suction flow path 2 that sucks and guides gas from the outside to the suction port 10a, and a discharge flow path 5 that supplies the gas compressed by the compressor main body 1 to the discharge side via the discharge port 10b. Is connected. The suction flow path 2 is provided with a suction filter 3 that removes foreign substances from the sucked gas, and an intake control valve 4 that opens and closes the suction flow path 2.

  When the intake control valve 4 is turned on, the suction flow path 2 is opened, and the load operation is performed in which the gas sucked by the compressor body 1 is compressed and discharged. On the other hand, when the intake control valve 4 is turned off, the suction passage 2 is closed, the supply of gas to the compressor body 1 is stopped, and an unload operation is performed in which the compressor body 1 does not compress the gas.

Further, the intake control valve 4 is maintained after a predetermined operation period has elapsed from the later time after the compressor 10 is newly introduced or the intake control valve 4 is maintained. The predetermined operation time is, for example, 32000 hours, which is the same as the inspection and replacement time of an electromagnetic valve (not shown) that is one of the components constituting the intake control valve 4. In the first embodiment, the allowable number of operations of the intake control valve 4 in a predetermined operation time means the allowable number N1 _{MAX of} turning on the intake control valve 4, that is, the allowable number of times that the compressor 10 performs the load operation, for example, 5 million times It is.

  The discharge channel 5 is provided with a pressure measuring device 6 for measuring the pressure on the discharge side and a reservoir 7. The compressed gas is supplied to the discharge side through the reservoir 7.

A control device (control means) 8 is connected to the pressure measuring device 6, and the control device 8 is connected to the intake adjustment valve 4. A pressure signal indicating the discharge pressure Po (bar) measured by the pressure measuring device 6 is input to the control device 8. The control device 8 outputs a control signal to the intake control valve 4 based on the input discharge pressure _PO or the shortest unloadable time T _U (s) described later, and performs on / off control of the intake control valve 4. . Further, a maintenance time measuring device (means) 11 and a load operation time measuring device (means) 12 are connected to the control device 8. The maintenance time measuring device 11 measures the remaining time T _M (s) until the maintenance of the intake adjustment valve 4. The load operation time measuring device 12 measures a continuation time (load time T _L (s)) from the start of the latest load operation.

An operation number measuring device (means) 13 for measuring the cumulative operation number of the intake adjustment valve 4 is connected to the intake adjustment valve 4, and this operation number measurement device 13 is connected to the control device 8. Here, in the first embodiment, the cumulative operation count of the intake adjustment valve 4 is the intake adjustment valve from the later time point after the compressor 10 is newly introduced or the intake adjustment valve 4 is maintained, whichever is later. 4 is that the cumulative number _{N1 oN} which is turned on.

Next, a pressure control method for the compressor 10 will be described. According to the pressure control method, the load during the operation of the compressor body 1 with a large discharge pressure P _O than the required minimum pressure is required at the discharge side P _{L (bar),} measured in the load operating time measuring device 12 loaded If the duration T _L of the start of the operation exceeds the unloadable shortest time T _U to be described later, it switches the compressor body 1 in the unload operation.

The pressure control method described above will be specifically described with reference to FIG. FIG. 2 shows a flow of the pressure control method according to the first embodiment of the present invention. When the operation of the compressor 10 is started, the pressure measuring device 6 first measures the discharge pressure Po in step S1. In step S <b> 2, the control device 8 determines whether or not the compressor body 1 is in a load operation based on the measured discharge pressure Po. If loading operation proceeds to step S3, the maintenance time measuring device 11 measures the remaining time T _M to maintenance of the intake regulating valve 4. The operating frequency measuring device 13 measures the cumulative number N1 _ON when the intake adjustment valve 4 described above is turned on, that is, the cumulative number of times that the compressor 10 is loaded.

In step S4, the controller 8 calculates the unloadable shortest time T _U. Unloadable shortest time T _U is defined by the following equation (1).
<Equation 1>
_{T U = Tm ÷ (N1 MAX} -N1 ON) (1)
Tm: Remaining time until maintenance of intake control valve 4 (s)
N1 _MAX : The allowable number of times that the intake adjustment valve 4 is turned on, which is the allowable number of operations of the intake adjustment valve 4. N1 _ON : The cumulative number of times that the intake adjustment valve 4 is turned on, which is the cumulative number of operations of the intake adjustment valve 4

Specifically to calculate the unload possible shortest time T _U. It is assumed that the compressor 10 is operated for the first time from the later time point after the introduction of the compressor 10 or the maintenance of the intake adjustment valve 4. At this time, the remaining time Tm until the intake adjustment valve 4 is maintained is 32,000 hours, which is the same as the inspection and replacement time of the intake adjustment valve 4 described above, and the cumulative number N1 _ON of the intake adjustment valve 4 being operated (turned on) is 0 times. In addition, it is assumed that the allowable operation number N1 _MAX of the intake adjustment valve 4 is 5 million times. When these numerical values are substituted into the above equation, the shortest unloadable time T _U when operating once (load operation) at that time is T _U = 32000 × 60 × 60 (s) ÷ (5 million (times) −0 (times)) = 23 (s).

As another example, the compressor 10 has already been operated for 10,000 hours from the time when the compressor 10 is newly introduced or the intake adjustment valve 4 is maintained, whichever is later, and is loaded 600,000 times. It is assumed that the engine is operated (the intake adjustment valve 4 is turned on). At this time, the remaining time Tm until the intake adjustment valve 4 is maintained is 22000 hours. Similarly to the above, the allowable operation number N1 _MAX of the intake adjustment valve 4 is 5 million times. When these numerical values are substituted into the above formula, the minimum unloadable time T _U at the time of operating once is T _U = 22000 × 60 × 60 (s) ÷ (5 million (times) −600,000 ( Times)) = 18 (s).

The controller 8 in step S5, the load time T _L is determined whether longer than unloadable shortest time T _U. Proceeds to step S6 if the load time T _L is longer than unloadable shortest time T _U, if not longer returns to step S1. The load operation time measuring device 12 measures the load time _TL that has continued from the start of the latest load operation.

In step S6, the pressure detector 6 measures the discharge-side pressure Po. Step S7, the control unit 8, the measured discharge pressure Po is determined whether or not it is necessary greater than the minimum pressure P _L. In the present embodiment, the minimum required pressure P _L is 6.0 (bar) but not limited thereto. When the discharge pressure Po is high, the process proceeds to step S8, and the load operation time measuring device 12 stops measuring the load time _TL . In step S9, the control device 8 turns off the intake adjustment valve 4, and switches the compressor 10 from the load operation to the unload operation. When the unload operation is started, the process returns to step S1. In step S7, even if the discharge pressure Po is not greater than the required minimum pressure P _L, the flow returns to step S1.

When the control device 8 determines in step S2 that the compressor 10 is not in the load operation, that is, in the unload operation, the process proceeds to step S10, and the pressure measuring device 6 measures the discharge pressure Po. Step S11, the control unit 8, the measured discharge pressure Po to determine the minimum required pressure P _L or less is. Proceeds to step S12 if it is less necessary minimum pressure P _L, the control unit 8 is turned on the intake regulating valve 4 is switched to the load operation of the compressor 10 from the unload operation. When the load operation is started, the process proceeds to step S13, and measurement of the time (load time T _L ) after the load operation time measuring device 12 starts the load operation is started. In step S14, one is added to the cumulative number N1 _{ON of} which the intake adjustment valve 4 is turned on, which is measured by the operation number measuring device 13, and the process returns to step S1.

When the control unit 8 in step S11, the pressure Po of the measured discharge side is determined not less necessary minimum pressure P _L, the flow returns to step S1.

As described above, when more than unloadable shortest time T _U, switch to unload operation of the compressor main body 1 from the load operation. Then, seeking in accordance with the cumulative operation times N1 _ON and remaining time Tm and the allowable operation number N1 _MAX of the unloadable shortest time T _U to maintenance of the intake regulating valve 4. As a result, the intake adjustment valve 4 is operated to the maximum of the allowable number of operations N1 _MAX , and the intake adjustment valve 4 is controlled in the shortest possible cycle, so that the pressure increase during the road operation can be kept small and energy saving operation can be performed. it can. As shown in FIG. 3, the area of the shaded area (integrated value of the discharge pressure during the operation time) in each cycle is smaller than the conventional one, confirming that the power consumption is reduced and energy-saving operation is performed. it can.

In addition, since the inspection and replacement timing of the intake adjustment valve 4 is determined by the product specifications, by controlling the intake adjustment valve 4 to be the expected allowable number of operations N1 _MAX when the inspection and replacement timing has elapsed, The operation number N1 _ON of the intake regulating valve 4 can be maximized within the range of the allowable operation number N1 _MAX . As a result, it is possible to prevent the intake adjustment valve 4 from reaching the allowable number of operations N1 _MAX prior to the inspection and replacement timing and being inspected and replaced at a time far from the original inspection and replacement timing.

  Next, the pressure control method will be specifically described with reference to the flow of the pressure control method according to the second embodiment of the present invention shown in FIG.

Steps S1 to S3 are the same as those in the first embodiment, and a description thereof will be omitted. In step S4, the controller 8 calculates the unloadable shortest time T _U. In addition, the operation frequency measuring device 13 measures the cumulative number N2 _ON in which an after-mentioned intake adjustment valve 4 is turned on and off, that is, the cumulative number in which the intake adjustment valve 4 is opened and closed.

In the first embodiment, defining the unloadable shortest time T _U in equation (1). In the second embodiment contrast, unloadable shortest time T _U is defined by the following equation (2).
<Equation 2>
T _U = Tm ÷ (N2 _MAX− N2 _ON ) × 2 (2)
Tm: Remaining time until maintenance of intake control valve 4 (s)
N2 _MAX : The allowable number of times that the intake adjustment valve 4 that is the allowable operation number of the intake adjustment valve 4 is turned on and off N2 _ON : The cumulative number of times that the intake adjustment valve 4 that is the cumulative operation number of the intake adjustment valve 4 is turned on and off

In the first embodiment, the allowable number of times of operation of the intake control valve 4 is the next maintenance from the time when the compressor 10 is newly introduced or the time after the intake adjustment valve 4 is maintained, whichever is later. It means the allowable number of times N1 _MAX that the intake adjustment valve 4 is turned on until. On the other hand, in the second embodiment, the allowable number of operation times of the intake control valve 4 is that the intake control valve 4 is turned on (opened) and off (closed) between the later time point and the next maintenance. ) Means the allowed number of times N2 _MAX .

In the first embodiment, the cumulative number of operations of the intake adjustment valve 4 means that the intake adjustment valve 4 is turned on from the later time after the compressor 10 is newly introduced or the intake adjustment valve 4 is maintained. It means that the accumulated number of times N1 is _ON . On the other hand, in the second embodiment, the cumulative number of operations of the intake adjustment valve 4 means the cumulative number N2 _ON of which the intake adjustment valve 4 is turned on and off from the later time point.

Specifically to calculate the unload possible shortest time T _U. The remaining time Tm from when the compressor 10 is newly introduced or after the intake adjustment valve 4 is maintained, whichever is later, until the intake adjustment valve 4 is maintained is the inspection and replacement of the intake adjustment valve 4. It is assumed that it is 32000 hours which is the same as the time. Further, it is assumed that the allowable opening / closing frequency N2 _MAX of the intake adjustment valve 4 is 5 million times that of the first embodiment, that is, 10 million times.

Further, it is assumed that the compressor 10 has already been operated for 10,000 hours from the later time point, and the intake adjustment valve 4 has been opened and closed 1.2 million times. At this time, the remaining time until the maintenance of the intake adjustment valve 4 is 22000 hours. When these numerical values are substituted into the above formula, the minimum unloadable time T _{U for} operating once at that time is T _U = 22000 × 60 × 60 (seconds) ÷ (10 million (times) −1.2 million ( Times)) × 2 = 18 (seconds).

Subsequent steps S5 to S9 are the same as those in the first embodiment, and a description thereof will be omitted. In step S9A, one time is added to the number of _{ON / OFF} times N2 _ON of the intake adjustment valve 4 measured by the operation number measuring device 13, and the process returns to step S1.

Since the control device 8 at step S2 determines that the compressor 10 is not in the load operation, the processing from step S10 to step S13, which is the same as that in the first embodiment, is omitted. In step S14A, one time is added to the _{ON / OFF} count N2 _ON of the intake adjustment valve 4 measured by the operation count measuring device 13, and the process returns to step S1.

In the second embodiment, to calculate the unloadable shortest time T _U by considering the number of times the intake regulating valve 4 is in addition to the number of open been turned closed is turned off. Therefore, by controlling the intake adjustment valve 4 in as short a cycle as possible, the pressure increase during the load operation can be suppressed to be small, and the energy saving operation can be performed.

The present invention is not limited to the above embodiment, and various modifications can be made.
The configuration of the compressor 10 is not particularly limited as long as the above-described compression control method can be performed. Further, the remaining time Tm until the maintenance of the intake adjustment valve 4, the allowable operation times N1 _MAX and N2 _MAX of the intake adjustment valve 4, and the cumulative operation times N1 _ON and N2 _ON of the intake adjustment valve 4 are not particularly limited.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Suction flow path 4 Intake regulating valve 8 Control apparatus (means)
11 Maintenance time measuring device (means)
12 Road operation time measuring device (means)
13 Operation frequency measuring device (means)

Claims (6)

A compressor body having a suction port for sucking gas, and a discharge port for discharging compressed gas sucked from the suction port;
A suction flow path for sucking gas from the outside to the suction port of the compressor body;
When turned on, the suction passage is opened and the compressor body is loaded, and when turned off, the suction passage is closed and the compressor body is unloaded, after a predetermined operation period has elapsed. An intake adjustment valve to be maintained;
Maintenance time measuring means for measuring the remaining time until maintenance of the intake regulating valve;
An operation frequency measuring means for measuring the cumulative operation frequency of the intake regulating valve;
Road operation time measuring means for measuring the duration from the start of the latest road operation;
Control means for switching between load operation and unload operation by turning on or off the intake adjustment valve;
With
The control means is in a load operation at a discharge pressure larger than the required minimum pressure required on the discharge side, and the duration from the start of the load operation measured by the load operation time measurement means is until the maintenance of the intake adjustment valve. The compressor switches to unload operation when the minimum unloadable time determined based on the remaining time of the engine, the allowable number of operations of the intake adjustment valve, and the cumulative number of operations of the intake adjustment valve is exceeded. The compressor according to claim 1, wherein the minimum unloadable time T _U (s) is defined by the following formula (1).
<Equation 1>
_{T U = Tm ÷ (N1 MAX} -N1 ON) (1)
Tm: Remaining time until maintenance of intake control valve (s)
N1 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on N1 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on The compressor according to claim 1, wherein the minimum unloadable time T _U (s) is defined by the following equation (2).
<Equation 2>
T _U = Tm ÷ (N2 _MAX− N2 _ON ) × 2 (2)
Tm: Remaining time until maintenance of intake control valve (s)
N2 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on and off N2 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on and off A compressor body having a suction port for sucking gas, and a discharge port for discharging compressed gas sucked from the suction port;
A suction flow path for sucking gas from the outside to the suction port of the compressor body;
When turned on, the suction passage is opened and the compressor body is loaded, and when turned off, the suction passage is closed and the compressor body is unloaded, after a predetermined operation period has elapsed. An intake adjustment valve to be maintained;
A pressure control method for a compressor comprising:
Measure the remaining time until maintenance of the intake valve,
Measure the cumulative number of operations of the intake control valve,
Measure the duration from the start of the most recent road operation,
During road operation at a discharge pressure larger than the required minimum pressure required on the discharge side, the duration from the start of the most recent road operation is the remaining time until the maintenance of the intake adjustment valve and the allowable number of operations of the intake adjustment valve. A compressor pressure control method for switching to an unload operation when a minimum unloadable time determined based on a cumulative operation count of the intake control valve is exceeded. 5. The compressor pressure control method according to claim 4, wherein the minimum unloadable time T _U (s) is defined by the following equation (1).
<Equation 1>
_{T U = Tm ÷ (N1 MAX} -N1 ON) (1)
Tm: Remaining time until maintenance of intake control valve (s)
N1 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on N1 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on 5. The compressor pressure control method according to claim 4, wherein the minimum unloadable time T _U (s) is defined by the following equation (2).
<Equation 2>
T _U = Tm ÷ (N2 _MAX− N2 _ON ) × 2 (2)
Tm: Remaining time until maintenance of intake control valve (s)
N2 _MAX : The allowable number of times that the intake adjustment valve that is the allowable operation number of the intake adjustment valve is turned on and off N2 _ON : The cumulative number of times that the intake adjustment valve that is the cumulative operation number of the intake adjustment valve is turned on and off

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