JP6703871B2 - Variable capacity compressor - Google Patents

Description

The present invention relates to a variable capacity compressor in which the setting of the pressure (rated pressure) of compressed gas supplied to the consumer side is variable, and more specifically, to a connected device such as a pneumatic device connected to the consumer side. The present invention relates to a variable capacity compressor including a protection device that protects the connected device by preventing the introduction of compressed gas exceeding the allowable pressure.

Compressors that generate compressed gas, such as compressed air, are used as a source of compressed air for pneumatic equipment such as excavators and rotary tools at civil engineering work sites, construction sites, factory facilities, etc. Engine-driven compressors equipped with an engine as a drive source for the main body are widely used outdoors where it is difficult to secure a power source or the like.

A configuration example of such a compressor 1'is shown in FIG. A compressor 1'shown in FIG. 8 includes a compressor body 2 which is an oil-cooled screw type that compresses a compressed gas together with lubricating oil as a compressor body 2 and discharges it as a gas-liquid mixed fluid. In the compressor 1 ′ provided with such an oil-cooled compressor body 2, in addition to the compressor body 2 and the drive source 3 such as a motor or an engine for driving the compressor body 2, the compressor body 2 Is provided with a receiver tank 4 for separating the lubricating oil from the compressed gas discharged by, and the compressed gas after the lubricating oil is separated in the receiver tank 4 is passed through an oil separator (not shown). Furthermore, after the oil content contained in the compressed gas is removed in the mist state, it can be supplied to the consumer side to which an air working machine (not shown) is connected, and is collected in the receiver tank 4. The lubricating oil thus prepared can be supplied to the compressor body 2 via the oil pipe 5 and the oil cooler 5a.

In such a compressor 1', in order to be able to supply a compressed gas of a predetermined pressure (rated pressure) to the consuming side, the discharge side pressure of the compressor body 2, the receiver tank 4 in the illustrated configuration. An intake control device 20 is provided to control the intake amount of the compressor body 2 in response to the change in the internal pressure.

As such an intake control device 20, in the compressor 1′ of FIG. 8, an intake control valve 21 provided at the intake port 2a of the compressor body 2, a closed valve pressure receiving chamber 21a of the intake control valve 21 and a receiver tank. A control flow path 22 communicating between the four and a pressure adjusting valve 23' for controlling the opening and closing of the control flow path 22 are provided.

Then, when the pressure in the receiver tank 4 exceeds the rated pressure from the state in which the control flow path 22 is closed, the pressure adjusting valve 23 ′ starts to open, and the opening degree increases in accordance with the pressure increase, and then it is fully opened. With this configuration, the intake control valve 21 in which the closed valve pressure receiving chamber 21a communicates with the receiver tank 4 via the pressure adjusting valve 23' is used to close the closed valve pressure receiving pressure in a state where the pressure in the receiver tank 4 is lower than the rated pressure. The working pressure is not introduced into the chamber 21a and the suction port 2a of the compressor body 2 is fully opened. However, when the pressure in the receiver tank 4 exceeds the rated pressure, introduction of compressed gas into the valve closed pressure receiving chamber 21a is started. The suction port 2a of the compressor body 2 is squeezed, and when the pressure regulating valve 23' is fully opened thereafter, the suction port 2a of the compressor body 2 is fully closed to shift to no-load operation and stop the generation of compressed gas. Therefore, the pressure in the receiver tank 4 is stopped at the maximum pressure (referred to as “no-load maximum pressure” in the present application) at the time of the transition to the no-load operation, and the compressed gas supplied to the consumer side is stopped. Perform intake control to bring the pressure close to the rated pressure.

In a compressor provided with such an intake control device 20, a so-called "variable capacity type" compressor in which the setting of the pressure (rated pressure) of the compressed gas supplied to the consumer side can be made variable Is also proposed.

As an example of such a variable displacement compressor, in Patent Document 1 described later, a pressure adjusting valve 23′ in the compressor described with reference to FIG. 8 is opened according to an input electric signal. There is described a variable displacement compressor provided with a control unit which is an electronic control device for changing the electro-pneumatic proportional valve to change the degree and controlling the operation of the electro-pneumatic proportional valve.

In this variable displacement compressor, the control unit stores in advance the relationship of the change in the correspondence relationship between the pressure in the receiver tank and the opening degree of the electropneumatic proportional valve with respect to the change in the set value of the rated pressure. The unit identifies the correspondence between the pressure in the receiver tank and the opening of the electro-pneumatic proportional valve based on the rated pressure set by the user, and determines the electro-pneumatic proportional valve based on the pressure in the receiver tank detected by the pressure sensor. By changing the output control signal, the pressure in the receiver tank can be controlled so as to approach the rated pressure, similarly to the intake control device using the pressure regulating valve 23', and the user can When the rated pressure setting is changed, the control unit identifies the correspondence between the pressure in the receiver tank and the opening of the electropneumatic proportional valve based on the changed rated pressure, and performs the intake control based on this. The pressure of the compressed gas supplied to the consumer side can be arbitrarily changed.

In addition, in the variable displacement compressor 1 in which the setting of the rated pressure is variable in this way, a device having a low normal pressure or an allowable pressure with respect to the set rated pressure (for example, 1.40 MPa) (for example, a normal pressure of 0.7 MPa, If you accidentally connect a pneumatic device with an allowable pressure of 1.0MPa) and start operation, compressed gas exceeding the allowable pressure will be supplied to the connected device, which may damage the connected device. However, there is a danger that the piping from the consumer side of the compressor to the connected equipment may burst or break.

Therefore, in the above-mentioned patent document 1, in order to prevent such an erroneous connection to the variable displacement compressor, the engine is not started unless the operator operates the confirmation operation means and then starts the operation. Alternatively, when the starting operation is performed without operating the confirmation operation means, the lowest discharge pressure is set within the range of the rated value that can be set, so that the pneumatic equipment is not damaged due to incorrect connection or It has been proposed to prevent the connection pipe from bursting or breaking (Patent Document 1 [0016] column, etc.).

Japanese Patent No. 4792015

In the variable displacement compressor introduced as the above-mentioned Patent Document 1, the engine does not start unless the operator operates the confirmation operation means, or the minimum pressure that can be set as the rated pressure is set as the rated pressure. Therefore, it is considered that there is a certain effect in preventing damage to the connected equipment and piping caused by human error such as incorrect connection.

However, the rated pressure set in the variable displacement compressor is equal to the allowable pressure or normal pressure of the connected equipment, and there is a human error (such as when the operator starts the engine in a prescribed procedure). Even if the human error does not exist, the intake control valve is closed even if the pressure in the receiver tank exceeds the rated pressure due to the failure of the control flow path or the electropneumatic proportional valve installed in the control flow path. If the compressed gas is not introduced into the valve pressure receiving chamber, or if the compressed gas at the pressure required to fully close the intake control valve is not introduced due to a leak or the like in the control flow path, the connected equipment will be used. Even if the pressure in the receiver tank rises due to a decrease in the amount of compressed air consumed by stopping the intake air, the intake control valve does not shift to no-load operation with the intake port of the compressor body fully closed. The compressor body 2 continues to generate compressed gas, and the pressure in the receiver tank continues to rise even if it exceeds the above-mentioned maximum no-load pressure.

In this way, the pressure in the receiver tank of the variable displacement compressor, and hence the pressure of the compressed gas supplied to the consumer side, further rises above the no-load maximum pressure for the set rated pressure, and Exceeding the permissible pressure may damage the connected equipment.

It should be noted that in the normal compressor, when the pressure in the receiver tank rises to a predetermined higher pressure than the rated pressure, a safety valve (not shown) opens and the compressed gas in the receiver tank is released, so that the receiver tank And pipes are prevented from being damaged.

Therefore, as described with reference to FIG. 8, in a general compressor whose rated pressure is fixed, the blowout pressure of the safety valve is set to a pressure approximately equal to the allowable pressure of the connecting device connected to the consumer side. By doing so, the safety valve can function not only as a protective device for the compressor, but also as a protective device for the connected device connected to the consumer side.

However, when the safety valve is installed in a variable displacement compressor whose rated pressure is variable, it is necessary to set the blowout pressure of the safety valve to a pressure higher than the maximum value of the pressure that can be set as the rated pressure. ..

As a result, a relatively low pressure (0.7 MPa as an example) is selected and set as the rated pressure from the range of pressure that can be set as the rated pressure (0.50 to 1.45 MPa as an example), and the normal pressure corresponding to this is selected. When an air pressure device with an allowable pressure (for example, a pneumatic device with a normal pressure of 0.7 MPa and an allowable pressure of 1.0 MPa) is connected and used, the pressure in the receiver tank will be reduced due to the failure of the electropneumatic proportional valve. When the safety valve is activated, the pressure of the safety valve is already significantly higher than the allowable pressure (1.0 MPa as an example) when the safety valve is activated. Since the compressed gas of 0.7MPa) is introduced, the above-mentioned safety valve is not a protective device for the connected equipment.

Therefore, the present invention has been made in order to solve the above-mentioned drawbacks of the prior art. In a variable displacement compressor in which the setting of the rated pressure can be changed, the set pressure can be handled regardless of the set value of the rated pressure. To provide a variable displacement compressor equipped with a protective device that protects connected equipment by preventing excessive pressure exceeding the allowable pressure from being introduced to connected equipment such as pneumatic equipment To aim.

The means for solving the problems will be described below together with the reference numerals used in the modes for carrying out the invention. This code is for clarifying the correspondence between the description of the claims and the description of the modes for carrying out the invention, and needless to say, it is limitedly used for the interpretation of the technical scope of the present invention. It is not something that can be done.

In order to achieve the above object, the variable capacity compressor 1 of the present invention comprises:
A control flow that connects the intake control valve 21 provided at the intake port 2a of the compressor body 2 and the valve closing pressure receiving chamber 21a of the intake control valve 21 to the discharge side of the compressor body 2 (receiver tank 4 in the embodiment). A path 22, an electropneumatic proportional valve 23 that opens and closes the control flow path 22, and an operation of the electropneumatic proportional valve 23 based on the set rated pressure and the detected value of the discharge side pressure of the compressor body 2. The electropneumatic proportional valve control means 24 is provided to operate the intake control valve 21 by opening/closing the control flow path 22 and increasing/decreasing the opening degree of the electropneumatic proportional valve 23. The intake control device 20 for controlling the intake air of the compressor main body 2 is provided so that the pressure approaches the rated pressure, and the set value of the rated pressure can be arbitrarily set within a predetermined pressure range to reduce consumption. In the variable displacement compressor 1 in which the setting of the pressure of the compressed gas supplied to the side is variable,
A bypass flow passage 41 that bypasses the electro-pneumatic proportional valve 23 and connects the discharge side (the receiver tank 4 in the embodiment) of the compressor body 2 and the valve closing pressure receiving chamber 21a of the intake control valve 21; Solenoid valves 42, 42' for opening and closing the flow path 41, and pressure abnormality in the discharge side pressure of the compressor body 2 are monitored and determined, and when the pressure abnormality is determined, the solenoid valves 42, 42' are operated. And a protection device 40 having a solenoid valve control means 43 for opening the bypass passage 41,
The solenoid valve control means 43 is
According to a preset correspondence relationship, based on the set value of the rated pressure, a pressure that is a predetermined high pressure with respect to the set value, and is lower than the allowable pressure of the connected device at the normal pressure corresponding to the set value. Calculate the upper limit pressure which is
The calculated upper limit pressure is compared with the detected value of the discharge side pressure of the compressor body 2 (the pressure inside the receiver tank 4 in the embodiment), and when the detected value is equal to or higher than the upper limit pressure, the pressure abnormality is determined. It is characterized by (claim 1).

After the determination of the pressure abnormality, the solenoid valve control means 43 keeps the bypass passage 41 open regardless of the change in the detected value of the discharge side pressure from the compressor body 2. 'May be configured to be retained (Claim 2).

Upper limit pressure described above, the compressor body of the discharge pressure predetermined with respect to the no-load maximum pressure is the maximum value that can be taken (the pressure in the receiver tank 4) value in the normal operation in the set value before Symbol rated pressure it can be set to β or high pressure (claim 3: see FIGS. 5 and 6).

When the solenoid valve control means 43 determines a pressure abnormality, it is supplied to the valve closing pressure receiving chamber 21a necessary to fully close the intake control valve 21 set based on a calculated value or an actually measured value obtained in advance. The set value of the pressure of the compressed gas is compared with the measured value of the pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21a detected by the second pressure sensor 51 or the like, and if the measured value is less than the set value. In some cases, an emergency stop means 52 for making an emergency stop of the drive source of the compressor body 2 may be further provided (claim 4).

A receiver tank 4 provided with an oil separator (not shown) for storing the compressed gas discharged from the compressor body 2 together with the lubricating oil is provided.
The control channel 22 and the bypass channel 41 may be connected to the receiver tank 4 on the primary side of the oil separation device so as to communicate with the discharge side of the compressor body 2 (claim 5). ..

With the configuration of the present invention described above, the variable capacity compressor 1 of the present invention can obtain the following remarkable effects.

A bypass flow passage 41 that bypasses the electro-pneumatic proportional valve 23 to communicate between the discharge side of the compressor body 2 and the closed pressure receiving chamber 21a of the intake control valve 21, and solenoid valves 42, 42 that open and close the bypass flow passage 41. ', and the protection device 40 including the solenoid valve control means 43 is provided, and the detected value of the discharge side pressure of the compressor body 2 (pressure in the receiver tank 4) has a predetermined upper limit pressure corresponding to the set rated pressure. Since the bypass flow passage 41 is configured to open when the temperature exceeds the limit, the electropneumatic proportional valve 23 provided in the control flow passage 22 fails and does not open or does not reach a predetermined opening degree. When the compressed gas for control is not supplied to the valve closing pressure receiving chamber 21a, or the compressed gas having the pressure necessary to fully close the intake control valve 21 is not introduced, the intake control valve 21 When the detected value of the discharge side pressure of the compressor body 2 (the pressure in the receiver tank 4) reaches the upper limit pressure due to the reason that the valve is not closed or the valve is delayed, the bypass flow passage 41 is opened and the intake air is taken. By closing the control valve 21 and shifting the engine-driven compressor to no-load operation, it is possible to prevent the discharge side pressure of the compressor body 2 (pressure inside the receiver tank 4) from further increasing, and to connect to the consumption side. It was possible to prevent compressed gas exceeding the upper limit pressure from being supplied to pneumatic equipment.

When the solenoid valve control means 43 is configured to hold the solenoid valves 42 and 42′ in the state in which the bypass flow passage 41 is opened after the pressure abnormality is determined, then the compressor main body 2 Intake using the electro-pneumatic proportional valve 23 and the control flow path 22 in which it is suspected that a malfunction such as a failure does not occur even if the discharge side pressure of the device falls below the rated pressure It was possible to prevent the control from being restarted.

At the set rated pressure, the discharge side pressure of the compressor main body 2 is a pressure higher than the maximum no-load maximum pressure, which is the maximum possible value, by a predetermined value β or more By setting the upper limit pressure below the allowable pressure of the pressure connecting device and opening the bypass flow passage 41 when the upper limit pressure is reached, the tolerance (manufacturing error, manufacturing error, It was possible to prevent malfunction of the solenoid valve provided in the bypass flow path, even if the maximum no-load pressure fluctuates slightly due to differences in operating environment such as during warm and cold weather.

When the solenoid valve control means 43 determines a pressure abnormality, the set value of the pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21a necessary to fully close the intake control valve 21 and the valve closing pressure A structure provided with an emergency stop means 52 which compares the measured value of the pressure of the compressed gas supplied to the chamber 21a and when the measured value is less than the set value, causes the drive source 3 of the compressor body 2 to make an emergency stop Then, in addition to the electro-pneumatic proportional valve 23, when the solenoid valves 42 and 42′ further fail, or when an abnormality such as clogging or breakage occurs in the control flow passage 22 or the bypass flow passage 41, introduction into the valve closing pressure receiving chamber 21a is performed. Even when the pressure is low and the compressor body 2 does not shift to no-load operation, the drive source 3 itself can be stopped to prevent a subsequent pressure increase, and excessive pressure is applied to the connected device connected to the consumer side. It was possible to more reliably prevent the compressed gas from being introduced.

In the configuration of the variable displacement compressor 1 including the receiver tank 4 having an oil separation device (not shown) for storing the compressed gas discharged from the compressor body 2, the compressor body 2 is of an oil cooling type. By communicating the control flow path 22 and the bypass flow path 41 with the receiver tank 4 on the primary side of the oil separation device, compressed air containing oil mist is supplied to both flow paths, and the electropneumatic proportional valve 23 is supplied. The mist oil facilitated the operation of sliding parts such as the pistons and valves of the solenoid valves 42 and 42', and other internal components, and the rust prevention of these parts could be achieved.

Further, since the oil film is formed on the inner surfaces of both the flow paths 22 and 41, even if water contained in the discharge air is condensed in the flow paths 22 and 41 to generate water drops, the inner surfaces of the flow paths 22 and 41 are formed. It was possible to cause water droplets to flow down together with the gas flow without adhering and staying, and to be sucked from the valve closing pressure receiving chamber 21a of the intake control valve 21 to the suction port 2a of the compressor body 2 via the escape passage 21b.

As a result, malfunctions of the electropneumatic proportional valve 23 and the solenoid valves 42, 42' can be reduced, and water droplets in the flow passages 22, 41 freeze and become uncontrollable, resulting in excess of connected devices connected to the consumer side. It was possible to prevent pressure and damage.

Explanatory drawing of the variable displacement compressor of this invention. Explanatory drawing which shows the modification of the variable displacement compressor of this invention. Explanatory drawing which shows another modification of the variable displacement compressor of this invention. The functional block diagram of a compressor control unit. Correlation diagram of rated pressure and upper limit pressure (example of setting upper limit pressure to stepless). Correlation diagram of rated pressure and upper limit pressure (example of setting upper limit pressure stepwise). The front view of an operation panel. Explanatory drawing of the conventional compressor.

The variable capacity compressor of the present invention will be described below with reference to the accompanying drawings.

In the following description, the variable displacement compressor according to the present invention will be described in such a manner that the drive source of the compressor body is an engine and that a lubricating oil is used as the compressor body for lubricating, cooling and sealing the compression action space. A configuration example in which a cold screw compressor is provided will be described, but the configuration of the variable capacity compressor of the present invention is not limited to these configurations.

[Overall structure of engine-driven compressor]
In FIG. 1, reference numeral 1 is a variable displacement compressor of the present invention. The variable displacement compressor 1 includes an engine 3 as a drive source and an oil-cooled screw compressor driven by the engine 3. The main body 2, the compressor main body 2 is provided with a receiver tank 4 for storing compressed gas discharged as a gas-liquid mixed fluid with lubricating oil, and in the receiver tank 4, the compressed gas and the lubricating oil are separated into gas and liquid, The compressed gas from which the lubricating oil has been separated is supplied to the consumer side via the check valve 4a, and the lubricating oil separated and collected in the receiver tank 4 is cooled by the oil cooler 5a via the oil pipe 5. After that, the compressor main body 2 is supplied again.

In order to make the pressure of the compressed gas supplied to the consuming side close to the set rated pressure, the variable displacement compressor 1 has a discharge side pressure (receiver tank 4 An intake control device 20 that controls the intake air of the compressor body 2 according to the change in the internal pressure) and a speed control device 30 that controls the rotation speed of the engine 3 are provided.

The intake control device 20 includes an intake control valve 21 provided at the intake port 2a of the compressor main body 2, a valve closing pressure receiving chamber 21a of the intake control valve 21 and a discharge side of the compressor main body 2. Then, a control flow path 22 that communicates between the receiver tanks 4, an electropneumatic proportional valve 23 that controls the opening and closing of the control flow path 22, and an electropneumatic proportional valve control means 24 that outputs a control signal to the electropneumatic proportional valve 23. In the present embodiment, the electro-pneumatic proportional valve control means 24 is realized by a compressor control unit 6 (which will be described later) that integrally controls the operation of the variable displacement compressor 1. The proportional valve control means 24 is specified by the rated pressure set by the user and the discharge side pressure of the compressor body 2 detected by the pressure sensor 7 (the pressure in the receiver tank 4) according to the preset correspondence relationship. The control signal corresponding to the opening that the electropneumatic proportional valve 23 should take is output.

The electro-pneumatic proportional valve 23 provided in the control flow passage 22 controls the opening degree of the valve provided therein according to the control signal from the electro-pneumatic proportional valve control means 24 to open and close the control flow passage 22 as well as the passage. The area can be changed so that the compressed gas introduced into the control flow path 22 on the downstream side of the electropneumatic proportional valve 23 is controlled, and when the electropneumatic proportional valve 23 is fully closed. When the intake control valve 21 is fully opened and the pressure in the receiver tank 4 exceeds the rated pressure, the electro-pneumatic proportional valve 23 opens, and the electro-pneumatic proportional valve 23 increases in opening degree with the increase in pressure, and eventually becomes full open. Thus, the suction port 2a of the compressor body 2 can be narrowed or closed.

The speed control device 30 described above includes an engine control unit (ECU) 32 provided in the engine 3 and a speed control means 31 that outputs a speed control signal to the ECU 32. In this case, the speed control means 31 is also realized by the compressor control unit 6 described later.

[Protection device]
As described above, the compressor of the present invention configured as a variable displacement compressor can be used as a pneumatic device or the like connected to the consumer side even if the electropneumatic proportional valve described above fails. On the other hand, a protective device 40 is provided to prevent the introduction of compressed gas that exceeds the allowable pressure of the pneumatic equipment.

This protection device 40 bypasses the electro-pneumatic proportional valve 23 and connects the discharge side of the compressor body 2 (receiver tank 4 in the example shown in the drawing) with the closed valve pressure receiving chamber 21 a of the intake control valve 21. A flow path 41, electromagnetic valves 42 and 42' for opening and closing the bypass flow path 41, and a pressure abnormality on the discharge side (receiver tank 4) of the compressor body 2 are monitored and determined, and the pressure abnormality is determined. At this time, the solenoid valve control means 43 is configured to open the bypass passage 41 by operating the solenoid valves 42 and 42'.

In the illustrated example, the both ends of the bypass flow passage 41 are connected to the control flow passage 22 on the primary side and the secondary side of the electropneumatic proportional valve 23, and a part of the flow passage is connected to the control flow passage 22. Although commonly used, the bypass flow passage 41 may be configured to directly communicate between the receiver tank 4 and the valve closing pressure receiving chamber 21a of the intake control valve 21 separately from the control flow passage 22.

In the example shown in FIGS. 1 and 2, a configuration in which an electromagnetic on-off valve is provided as the electromagnetic valve 42 that opens and closes the bypass flow passage 41 is adopted, but instead of this configuration, as shown in FIG. 3, control on the receiver tank 4 side is performed. A three-way solenoid valve 42' may be provided at a branch point between the flow passage 22 and the bypass flow passage 41. In this configuration, either the control flow passage 22 or the bypass flow passage 41 is selected by the three-way solenoid valve 42'. By bypassing the receiver tank 4, the bypass flow channel 41 can be opened and closed.

In order to control the opening/closing of the solenoid valves 42, 42', the compressor control unit 6 is further provided with a solenoid valve control means 43 in addition to the electropneumatic proportional valve control means 24 and the speed control means 31 described above. This solenoid valve control means 43 calculates the upper limit pressure for the rated pressure set by the user according to the preset correspondence relationship between the rated pressure and the upper limit pressure, and the calculated upper limit pressure, The pressure in the receiver tank 4 detected by the pressure sensor 7 is compared, and when the pressure in the receiver tank 4 becomes equal to or higher than the upper limit pressure, a pressure abnormality in the receiver tank 4 is determined, and a control signal for opening the bypass flow passage 41. To the solenoid valves 42, 42'.

In this way, the solenoid valves 42, 42 ′ open the bypass flow passage 41, so that in the configuration shown in FIGS. 1 and 2, the compressed gas in the receiver tank 4 passes through the bypass flow passage 41 and the intake control valve 21 flows. It is prevented that the pressure in the receiver tank 4 exceeds the upper limit pressure and further rises when the pressure is introduced into the valve closing pressure receiving chamber 21a and the compressor main body 2 stops the intake to stop the generation of compressed gas.

Instead of the configuration shown in FIG. 1 and FIG. 2, as shown in FIG. 3, a three-way solenoid valve 42′ is provided at the branch point of the control flow passage 22 and the bypass flow passage 41 on the receiver tank 4 side, and either one of the flow passages is provided. In the configuration in which (22 or 41) can be selectively communicated with the receiver tank 4, a pressure adjusting valve 44 is provided in the bypass flow passage 41, and the operating pressure of the pressure adjusting valve 44 is set to a variably set rated pressure. Configure to set to minimum pressure.

In this configuration, when the solenoid valve control means 43 determines that the pressure in the receiver tank 4 is abnormal, the solenoid valve 42' is then set to the switching position in which the bypass passage 41 is opened regardless of the pressure change in the receiver tank 4. In the case where the electropneumatic proportional valve 23 fails, the intake air control thereafter can be performed by the pressure adjusting valve 44 provided in the bypass flow passage 41, and the compressed gas can be supplied to the consumer side. It is possible to continue.

In this configuration, since the rated pressure set by the pressure adjusting valve 44 is the lowest pressure that can be variably set, the rated pressure before the pressure abnormality judgment is set to any of low pressure, medium pressure, and high pressure. Even if there is, after the transition to the intake control by the bypass flow passage 41 and the pressure adjusting valve 44, the compressed gas having a pressure exceeding the allowable pressure of the pneumatic equipment connected to the consumer side is not supplied and is connected. It is possible to prevent damage to the pneumatic equipment.

When the compressed gas is supplied to the medium-pressure or high-pressure pneumatic equipment in the compressor 1 after shifting to the intake control by the bypass flow passage 41 and the pressure adjusting valve 44 in this manner, the operator uses the pneumatic equipment to be used. It suffices to adjust the pressure setting of the pressure adjusting valve 44 in accordance with the pressure specification of No. 1, whereby the supply of the compressed gas to not only the low pressure pneumatic equipment but also the medium pressure or high pressure pneumatic equipment can be continued. ..

The pressure adjusting valve 44 may be adjusted to an operating pressure corresponding to the rated pressure set in advance as a variable pressure that can be set. In this case, the operator is required to change the setting of the pressure adjusting valve 44 every time the setting of the rated pressure is changed. However, the intake control by the bypass flow passage 41 and the pressure adjusting valve 44 is performed by the determination of the pressure abnormality. Even after the transition, it is possible to continuously supply compressed gas having a pressure corresponding to the set rated pressure to the pneumatic equipment connected to the consumer side.

In the configuration shown in FIG. 1, only the protection device 40 including the bypass flow passage 41, the on-off valve 42, and the on-off valve control means 43 is provided as a protection device for the connected device connected to the consumer side. In addition to this, as shown in FIG. 2 and FIG. 3, in addition to the case where the control flow path 22 or the electropneumatic proportional valve 23 side has a problem such as clogging or failure, the bypass flow path is also provided. Even when a malfunction such as clogging or failure occurs on the side of 41 or the solenoid valves 42, 42', it is prevented that an excessive pressure exceeding the allowable pressure is supplied to the connected device connected to the consumer side. For this purpose, an emergency stop device 50 may be provided.

As such an emergency stop device 50, the variable displacement compressor 1 shown in FIGS. 2 and 3 has a second pressure sensor 51 for detecting the pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21 a of the intake control valve 21. And an emergency stop means for monitoring the pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21a based on the detection signal of the second pressure sensor 51 and outputting an emergency stop signal to the ECU 32 of the engine 3 based on the monitoring result. 52 is provided.

In the present embodiment, the emergency stop means 52 is realized by the pressure control unit 6 described above, and the emergency stop means 52 is configured such that the solenoid valve control means 43 of the protection device 40 described above determines the pressure abnormality of the receiver tank 4. The pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21a detected by the second pressure sensor 51 when the control signal for opening the bypass flow passage 41 is being output to the solenoid valves 42, 42'. When the measured value is less than the set value, the measured value is compared with the set value set as the pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21a required to fully close the intake control valve 21. ，The above-mentioned emergency stop signal is output to stop the engine in an emergency.

[Electronic control system]
(1) Overall Configuration The electropneumatic proportional valve control means 24, speed control means 31, solenoid valve control means 43, and emergency stop means 52 described above each include a microprocessor, MPU (Micro Processing Unit), or the like. The electronic control device is realized by executing a predetermined program, and in the present embodiment, each of these means is an electronic control device for centrally controlling the operation of the variable displacement compressor 1. , Is realized by the compressor control unit 6.

Therefore, the compressor control unit 6 in the variable displacement compressor according to the present invention is the same as the compressor control unit 6 of the known variable displacement compressor 1 that originally includes the electropneumatic proportional valve control means 24 and the speed control means 31. It can be obtained by additionally writing a program for realizing the solenoid valve control means 43 and the emergency stop means 52 described above.

As shown in FIG. 4, the compressor control unit 6 includes an input unit 80 including an operation panel and switches for the user to perform a rated pressure setting operation, an engine 3 (the ECU 32 of the engine 3 and a rotation speed). Detection means), a pressure sensor 7 for detecting the pressure in the receiver tank 4, a second pressure sensor 51 for detecting the pressure of the compressed gas supplied to the closed valve pressure receiving chamber 21a of the intake control valve 21, an electropneumatic proportional valve 23. And the electromagnetic valves 42, 42' are connected to form an electronic control system, and the state of each unit received by the compressor control unit 6 from the input unit 80, the ECU 32, the rotation speed detecting means, and the pressure sensor (7, 51). In response, the control signal is output to the electro-pneumatic proportional valve 23, the electromagnetic on-off valves 42 and 42', and the ECU 32 to control each part.

In the present embodiment, the compressor control unit 6 is provided as a unit that integrally controls the operation of the engine-driven variable displacement compressor as described above. In addition to the electro-pneumatic proportional valve control means 24, the speed control means 31, the solenoid valve control means 43, and the emergency stop means 52 described above, the engine start/stop, various settings, warnings, and other indications, and other necessary Although means for controlling is realized, in the following description, only means related to the present invention will be described, and description of other means will be omitted.

(2) Input Unit In order to make the setting of the rated pressure changeable, the variable displacement compressor 1 of the present invention is provided with an input unit 80 for the user to input for setting the rated pressure.

In the present embodiment, the input unit 80 is a set prohibition switch provided at a position apart from the rated pressure setting switches (82 to 86) provided on the operation panel as shown in FIG. 7 and the operation panel. It is composed of 81.

Of these, the setting prohibition switch 81 is configured to be able to switch between a “permit” position and a “prohibit” position. With the setting prohibition switch 81 set to the “prohibit” position, the rated pressure setting provided on the operation panel is set. Even if the switches (82-86) for the operation are operated, the set pressure cannot be changed, so that the setting of the rated pressure will not be changed unintentionally by an erroneous operation. ..

In the present embodiment, on the operation panel, as switches for setting a rated pressure, “low pressure (0.5 to 0.75 MPa)”, “intermediate pressure (0.76 to 1.08 MPa)”, and “high pressure (1.09 to 1.45MPa)” to select the rated pressure setting range, the pressure value within the pressure range selected by the setting range selection switch (82, 83, 84) and the setting range selection switch (82, 83, 84) "UP" and "DOWN" switches (84, 85; in the example shown, the UP switch is also used as the high-voltage selection switch 84) for selecting, and after the setting is completed, the setting contents are confirmed and completed. A “fix” switch 86 is provided.

When changing the setting of the rated pressure, the user first switches the setting prohibition switch 81 to the "permit" position through the input unit 80, and then uses the setting range selection switch to switch the pressure range to be set. (For example, the low pressure switch 82) is pressed and held, the lamp 82a provided on this switch is made to blink, and the set value of the discharge pressure displayed on the display section 87 is set by operating the UP switch 84 or the DOWN switch 85. When the setting/decision switch 86 is pressed after setting the numerical value, the setting of the rated pressure stored in the storage unit of the compressor control unit 6 described later is rewritten.

After that, the user returns the setting prohibition switch 81 to the “prohibition” position, and the setting work of the rated pressure is completed.

(3) Compressor control unit
(3-1) Overall Configuration of Compressor Control Unit The compressor control unit 6 includes a storage unit 6a that stores the rated pressure and various programs set by the user by the method described above, and the engine 3 (ECU 32 of the engine and rotation speed detection). Means) and the data received from the pressure sensors 7 and 51 according to a program stored in the storage unit 6a, and a control signal obtained based on the calculation processing is applied to the ECU 32 of the engine 3 and the electropneumatic proportional valve 23, And an arithmetic processing unit 6b for outputting to the solenoid valves 42, 42'.

(3-2) Arithmetic processing section In the speed control means 31, the electropneumatic proportional valve control means 24, the solenoid valve control means 43, and the emergency stop means 52, the arithmetic processing section 6b described above is stored in the storage section 6a. It is realized by executing a predetermined program.

Among them, the speed control means 31 calculates the rotation speed of the engine 3 based on the preset value of the rated pressure and the pressure in the receiver tank 4 detected by the pressure sensor 7 in accordance with the preset correspondence relationship, and the rotation of the engine 3 A speed control signal is output to the ECU 32 of the engine 3 so that the speed matches the calculated rotation speed.

Further, the electro-pneumatic proportional valve control means 24 is a receiver that the electro-pneumatic proportional valve 23 provided in the control flow path 22 detects the set value of the rated pressure set by the user and the pressure sensor 7 according to the preset correspondence relationship. A control signal is output to the electropneumatic proportional valve 23 so that the opening degree becomes a predetermined opening specified by the pressure in the tank 4.

Further, the solenoid valve control means 43 described above calculates the upper limit pressure based on the set value of the rated pressure set by the user according to the preset correspondence relationship, and measures the pressure in the receiver tank 4 detected by the pressure sensor 7. The value is compared with the upper limit pressure, and when the measured value is equal to or higher than the upper limit pressure, a pressure abnormality of the receiver tank is determined, and a control signal for opening the bypass flow passage 41 is sent to the solenoid valves 42, 42'. Output.

Further, as shown in FIGS. 2 and 3, the emergency stop means 52 provided in the arithmetic processing unit 6b has a second pressure for detecting the pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21a of the intake control valve 21. This is a means provided when the configuration in which the sensor 51 is provided is adopted, and the solenoid valve control means 43 outputs a control signal for opening the bypass flow passage 41 to the solenoid valves 42, 42' by determining the pressure abnormality in the receiver tank 4. In this state, the pressure of the compressed gas supplied to the closed valve pressure receiving chamber 21a of the intake control valve 21 detected by the second pressure sensor 51 is intaken based on a previously calculated value or an actually measured value. The pressure of the compressed gas supplied to the valve closing pressure receiving chamber 21a detected by the second pressure sensor 51 is compared with the set value stored in the storage unit as the pressure required to fully close the control valve. If it is less than this set value, the ECU 32 of the engine 3 outputs an emergency stop signal for stopping the engine 3 in an emergency.

Although not shown, the above-mentioned arithmetic processing unit 6b detects a detection signal from a rotation speed detection unit that detects the rotation speed of the engine 3 and a generated voltage or current of a power generator such as an alternator provided in the engine 3. An operating state determination means for determining the operating state of the engine (stop, start, transition to stable operation after start) based on the value, the detected value of the oil pressure of the engine 3, the count time by the timer, and the like may be provided. ..

In this case, irrespective of the pressure in the receiver tank 4 detected by the pressure sensor 7 at the time of starting the engine 3 or during the time from the start to the transition to stable operation based on the judgment result of the operation state judging means, FIG. In the apparatus configuration shown in FIG. 2, the solenoid valve control means 43 may be configured to output a control signal for opening the bypass flow passage 41 to the solenoid valve 42. In the apparatus configuration shown in FIG. The control means 43 is caused to output a control signal for opening the control flow path 22 and closing the bypass flow path 41 to the solenoid valve (three-way solenoid valve) 42', and the electro-pneumatic proportional valve control means 24 for the electro-pneumatic proportional valve 23. May be configured to output a control signal for fully opening.

With this configuration, when the engine 3 is started, the closed valve pressure receiving chamber 21a of the intake control valve 21 communicates with the receiver tank 4, and the compression introduced into the receiver tank 4 by the rotation of the compressor body 2 is performed. Since the gas is immediately introduced into the closed valve pressure receiving chamber 21a of the intake control valve 21 to close the suction port 2a of the compressor body 2 for no-load operation, the bypass flow passage 41, the control flow passage 22, the electromagnetic flow passage 22 The valves 42, 42' and the electropneumatic proportional valve 23 can also be provided with a function as a starting load reducing device that reduces the load on the engine in an unstable operating state immediately after starting.

(3-3) Storage Unit In the storage unit described above, the rated pressure input and set by the user via the input unit 80 is stored, and the pressure in the receiver tank 4 is corresponding to the rated pressure. The speed control means 31 and the electropneumatic proportional valve described above are provided so that the speed control of the engine according to the change, the intake control of the compressor body, the opening/closing of the bypass passage 41 and the emergency stop of the engine 3 can be performed. A program for realizing the control means 24, the solenoid valve control means 43, and the emergency stop means 52 is stored.

In order to change the operation pattern of the rotational speed control of the engine 3 and the intake control of the compressor main body 2 in response to the change of the setting of the rated pressure, for the change of the rated pressure in the presettable numerical range, The correspondence relationship of how the relationship between the pressure in the receiver tank 4, the rotation speed of the engine 3, and the opening degree of the electropneumatic proportional valve 23 changes is obtained, and the ECU 32 of the engine 3 is based on this correspondence relationship. When a user changes the setting of the rated pressure by storing the program for generating the speed control signal output to the control valve and the control signal output to the electropneumatic proportional valve 23 in the storage unit 6a, the set rated pressure is set to the set rated pressure. The speed control means 31 and the electropneumatic proportional valve control means 24 are configured to execute corresponding speed control and intake control.

Further, in order to enable the opening/closing control of the solenoid valves 42 and 42′ provided in the protection device 40, the storage unit 6a of the compressor control unit 6 stores the correspondence relationship between the rated pressure and the upper limit pressure, The solenoid valve control means 43 is caused to calculate the upper limit pressure based on the rated pressure set by the user based on this correspondence, and the pressure in the receiver tank detected by the pressure sensor is compared with the calculated upper limit pressure to make the receiver tank. A program for outputting a control signal for opening the bypass passage 41 when the internal pressure becomes equal to or higher than the upper limit pressure is stored.

Here, the intake control valve 21 performs intake control so that the pressure in the receiver tank 4 approaches the rated pressure set by the user, but the intake control valve 21 causes the pressure in the receiver tank 4 to exceed the rated pressure. At this time, the suction port 2a of the compressor body 2 starts to be squeezed, and then the suction port 2a is fully closed to shift to the no-load operation when the pressure in the receiver tank 4 further increases. The pressure in the tank 4 exceeds the rated pressure and rises to the above-mentioned maximum no-load pressure.

Therefore, in the present embodiment, the discharge side pressure (the pressure in the receiver tank 4) of the compressor body for which the intake control is normally performed can be taken for each settable rated pressure based on the actual measurement value or the like. The maximum load pressure is calculated in advance, and the upper limit is set so that the pressure is higher than the no-load maximum pressure by a predetermined value β or more, and is less than the allowable pressure in the pneumatic equipment at the normal pressure corresponding to the set rated pressure. The pressure is set, and the control program based on this upper limit pressure is stored in the storage unit 6a.

Here, in the pneumatic device connected to the consuming side of the variable displacement compressor 1 and working with compressed gas, the normal pressure of the compressed gas to be used and the allowable pressure that can withstand the use are predetermined. a pneumatic devices atmospheric pressure of, 0.7 MPa (low-pressure) as an example, 1.03 MPa (medium pressure), 1.4 MPa are divided in advance by the application and so on (high), the allowable pressure greater pressure segment each Is set in advance (see FIGS. 5 and 6).

Therefore, the no-load maximum pressure for each rated pressure is, for example, the no-load maximum pressure is actually measured for any rated pressure at low pressure, medium pressure, and high pressure. Draw the straight line that rises to the right, and obtain it in advance by reading or calculating the relational expression of this straight line, and allow the upper limit pressure for each variably set rated pressure to the unloaded maximum pressure. The value β is added so that the upper limit pressure is set to be equal to or lower than the allowable pressure of the pneumatic equipment at each of the low pressure, the medium pressure, and the high pressure.

The permissible value β may be set as a constant and the upper limit pressure may be set as a straight line that gradually increases to the right as shown by the dotted line in FIG.

In addition, as shown in FIG. 6, this upper limit pressure is, for example, the maximum no-load at any settable pressure (for example, 0.70 MPa, 1.05 MPa, 1.40 MPa) in each pressure range of low pressure, medium pressure, and high pressure. A value obtained by adding the allowable value β to the upper limit value of pressure, therefore, one upper limit pressure (a total of three upper limit pressures) is set for each pressure range, and this upper limit pressure is lower than the allowable pressure of the pneumatic equipment. You may set so that it becomes.

Based on the relationship between each set pressure and the upper limit pressure thus obtained, the solenoid valve control means 43 calculates the upper limit pressure corresponding to this rated pressure based on the set value of the rated pressure stored in the storage unit 6a, The pressure in the receiver tank 4 detected by the pressure sensor 7 is compared with the calculated upper limit pressure, and when the pressure in the receiver tank 4 becomes equal to or higher than the upper limit pressure, the bypass passage 41 is opened.

In addition, in FIG. 5 and FIG. 6, the two-dot chain line graph shown at the top shows the blowout pressure of the safety valve, and from the allowable value β with respect to the maximum no-load pressure at the maximum value of variably settable rated pressure, Is also set by adding a predetermined allowable value α.

In the illustrated example, the safety valve outlet pressure is set to a pressure higher than the high pressure equipment allowable pressure, but the safety valve outlet pressure may be set to the same pressure as the high pressure equipment allowable pressure.

[Operation, etc.]
In the variable displacement compressor 1 of the present invention configured as described above, after the user operates the switches provided in the input section 80 to complete the input and setting of the rated pressure, the engine 3 is started to perform compression. When the machine body 2 is rotated to start the generation of compressed gas, the compressed gas generated by the rotation of the compressor body 2 is introduced into the receiver tank 4.

When the compressed gas is consumed in the connected device connected to the consumer side, the pressure in the receiver tank 4 is equal to or lower than the set rated pressure, and the speed control means receives the detection signal of the pressure sensor 7. Reference numeral 31 outputs a speed control signal for setting the engine 3 at a full load operating speed, and electro-pneumatic proportional valve control means 24 outputs a control signal for fully closing the electro-pneumatic proportional valve 23 to turn on the intake control valve 21. Perform full load operation with full opening.

When the pressure in the receiver tank 4 exceeds the rated pressure because the consumption of compressed gas is reduced or stopped due to the suspension of the use of pneumatic equipment, the speed control means 31 that has received the detection signal of the pressure sensor 7 causes the speed control means 31 of the engine 3 to receive the detection signal. The speed control signal for decelerating the speed is output to the ECU 32 of the engine 3, and the electropneumatic proportional valve control means 24 outputs a control signal for narrowing the electropneumatic proportional valve 23 to the electropneumatic proportional valve 23, which the pressure sensor 7 detects. When the pressure in the receiver tank 4 further rises, the speed control means 31 outputs a speed control signal for decelerating the engine to a no-load operation, and the electropneumatic proportional valve control means 24 controls the electropneumatic proportional valve 23 to be fully opened. When a signal is output to close the intake control valve, the compressor is transferred to no-load operation, and the control flow path 22 and the electropneumatic proportional valve 23 are functioning normally, the above-mentioned speed is set. Control and intake control are repeated.

On the other hand, an abnormality occurs in the control flow path 22 or the electropneumatic proportional valve 23, the pressure in the receiver tank 4 detected by the pressure sensor 7 exceeds the rated pressure set by the user, and the electropneumatic proportional valve control means 24 Even though the valve opening signal is output to the electro-pneumatic proportional valve 23, the intake air of the compressor body 2 is not throttled, and the compressor body 2 does not shift to the no-load operation. When the pressure rises and reaches the upper limit pressure corresponding to the set rated pressure, the solenoid valve control means 43 determines a pressure abnormality in the receiver tank 4, and the solenoid valve 42 provided in the bypass flow passage 41, A control signal for opening the bypass flow passage 41 is output to 42 ′, the electropneumatic proportional valve 23 is bypassed, and the receiver tank 4 and the valve closing pressure receiving chamber 21 a of the intake control valve 21 are connected.

As a result, the compressed gas in the receiver tank 4 is introduced into the closed valve pressure receiving chamber 21a of the intake control valve 21, and the intake control valve 21 closes the intake port 2a of the compressor body 2 to shift to no-load operation and compress. The generation of the compressed gas by the machine body 2 is stopped, and the pressure increase in the receiver tank 4 is stopped, so that the compressed gas exceeding the allowable pressure is prevented from being introduced into the pneumatic device connected to the consumer side. It

Further, since the upper limit pressure is set to a pressure lower than the safety valve blowout pressure, the pressure in the receiver tank does not rise above the safety valve blowout pressure, and it is possible to prevent the safety valve from blowing.

When the solenoid valve control means 43 determines the pressure abnormality in the receiver tank 4 and opens the bypass passage 41, the pressure change in the receiver tank 4 is changed until a predetermined operation such as operation of a reset switch is performed. Regardless of the above, the bypass channel 41 is configured to be maintained in an open state, and thereafter, even when the pressure in the receiver tank 4 is reduced due to consumption of compressed gas on the consumption side, It is preferable that the suction port 2a of the compressor body 2 can be maintained in a closed state.

Further, in the configuration shown in FIGS. 1 and 2, after the solenoid valve control means 43 determines the pressure abnormality in the receiver tank 4 and opens the bypass flow passage 41, the speed control means 31 also receives the receiver tank 4 after that. It is preferable that the control signal for fixing the rotation speed of the engine 3 to the no-load rotation speed is output to the engine 3 regardless of the change in the internal pressure.

With such a configuration, when abnormality occurs in the intake control using the control flow path 22 and the electropneumatic proportional valve 23, not only the intake control valve 21 is kept fully closed, but also the engine rotation speed is reduced. By maintaining the state where the load rotation speed is reduced, the rotation speed of the compressor body 2 can be reduced to suppress an increase in the discharge pressure, and further, noise reduction and fuel consumption after a no-load operation transition can be reduced. it can.

In the configuration shown in FIG. 3, one of the control channel 22 and the bypass channel 41 is configured to selectively communicate with the receiver tank 4, and the bypass channel 41 can be variably set. There is provided a pressure adjusting valve 44 adjusted to an operating pressure corresponding to the minimum rated pressure.

Therefore, in this configuration, the pressure in the receiver tank 4 detected by the pressure sensor 7 becomes equal to or higher than the upper limit pressure, and the solenoid valve control means 43 determines the pressure abnormality of the receiver tank 4 and closes the control flow path 22. By opening the bypass passage 41, and thereafter, the solenoid valve control means 43 is configured so that the three-way solenoid valve 42 ′ holds the switching position where the bypass passage 41 is opened regardless of the pressure change in the receiver tank 4. It is possible to perform the intake control by the pressure adjusting valve 44, whereby the variable displacement compressor 1 can be continuously used and the compressed gas can be continuously supplied to the pneumatic equipment.

Therefore, in the description with reference to FIGS. 1 and 2, when the pressure in the receiver tank 4 exceeds the upper limit pressure and the solenoid valve control means 43 determines a pressure abnormality in the receiver tank 4, the speed control means 31 and the engine 3 Although it has been described that it is preferable to fix the rotation speed to the no-load rotation speed, in the structure shown in FIG. 3, the speed control means 31 determines the pressure after the solenoid valve control means 43 determines the pressure abnormality. The speed control corresponding to the minimum value of the rated pressure that can be variably set according to the pressure in the receiver tank 4 detected by the sensor 7 may be performed.

1 Variable capacity compressor 1'Compressor (fixed capacity type)
2 Compressor body 2a Suction port 3 Drive source (engine)
4 receiver tank 4a check valve 5 oil pipe 5a oil cooler 6 compressor control unit 6a storage unit 6b arithmetic processing unit 7 pressure sensor 20 intake control device 21 intake control valve 21a closed valve pressure receiving chamber 21b escape flow channel 22 control flow channel 23 Electro-pneumatic proportional valve 23' Pressure adjusting valve 24 Electro-pneumatic proportional valve control means 30 Speed control device 31 Speed control means 32 Engine control unit (ECU)
33 Rotation speed detection means (rotation speed sensor)
40 Protective device 41 Bypass flow path 42 Solenoid valve (solenoid on-off valve)
42' solenoid valve (three-way solenoid valve)
43 Solenoid valve control means 44 Pressure adjusting valve 50 Emergency stop device 51 Second pressure sensor 52 Emergency stop means 80 Input section 81 Setting prohibition switch 82 Setting range selection switch (low pressure switch)
83 Setting range selection switch (medium pressure switch)
84 Setting range selection switch (high pressure switch) and UP switch 82a, 83a, 84a Lamp 85 DOWN switch 86 Setting/confirmation switch 87 Display

Claims (5)

An intake control valve provided at the intake port of the compressor body, a control flow passage that connects the valve closing chamber of the intake control valve to the discharge side of the compressor body, and an electropneumatic proportional valve that opens and closes the control flow passage. And an electropneumatic proportional valve control means for controlling the operation of the electropneumatic proportional valve on the basis of the set rated pressure and the detected value of the discharge side pressure of the compressor body. By operating the intake control valve by opening/closing the passage and increasing/decreasing the opening, an intake control device is provided for controlling the intake of the compressor main body so that the discharge side pressure of the compressor main body approaches the rated pressure. In the variable capacity compressor in which the setting value of the rated pressure can be arbitrarily set within a predetermined pressure range, and the setting of the pressure of the compressed gas supplied to the connection device on the consumption side is variable,
A bypass flow passage that bypasses the electro-pneumatic proportional valve to communicate between the discharge side of the compressor body and the closed pressure receiving chamber of the intake control valve, a solenoid valve that opens and closes the bypass flow passage, and the compressor. A protection device including a solenoid valve control means for monitoring and determining a pressure abnormality in the discharge side pressure of the main body, and operating the solenoid valve to open the bypass passage when the pressure abnormality is determined;
The solenoid valve control means is
According to a preset correspondence, based on the set value of the rated pressure, a pressure that is a predetermined high pressure with respect to the set value , and a pressure that is lower than the allowable pressure of the connected device at the normal pressure corresponding to the set value. Calculate the upper limit pressure which is
A variable displacement compressor characterized by comparing the calculated upper limit pressure with a detection value of the discharge side pressure of the compressor body, and determining the pressure abnormality when the detected value is equal to or higher than the upper limit pressure. After the pressure abnormality is determined, the solenoid valve control means holds the solenoid valve in the state in which the bypass passage is opened regardless of a change in the detected value of the discharge side pressure of the compressor body. The variable capacity compressor according to claim 1. To be a predetermined value or more high pressure to the no-load maximum pressure is the maximum value of discharge pressure can be taken of the compressor body in a normal operation in the set value before Symbol rated pressure was set to the upper limit pressure The variable capacity compressor according to claim 1 or 2, wherein. When a pressure abnormality is determined by the solenoid valve control means, the set value of the pressure of the compressed gas supplied to the closed valve pressure receiving chamber necessary to fully close the intake control valve and the pressure of the compressed gas supplied to the closed valve pressure receiving chamber are supplied. The emergency stop means for stopping the drive source of the compressor main body in an emergency is provided when the measured value of the compressed gas is compared with the measured value and the measured value is less than the set value. [3] The variable capacity compressor according to any one of [3] to [3]. An oil cooling type compressor body is provided, and a receiver tank provided with an oil separation device for storing compressed gas discharged from the compressor body together with lubricating oil is provided.
The control flow path and the bypass flow path are connected to the receiver tank on the primary side of the oil separation device so as to communicate with the discharge side of the compressor body. Variable capacity compressor described.

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