CN113653625A

CN113653625A - Engine-driven compressor and operation control method thereof

Info

Publication number: CN113653625A
Application number: CN202110515509.XA
Authority: CN
Inventors: 桐生贡
Original assignee: Hokuetsu Industries Co Ltd
Current assignee: Hokuetsu Industries Co Ltd
Priority date: 2020-05-12
Filing date: 2021-05-12
Publication date: 2021-11-16
Also published as: JP7427523B2; JP2021179186A

Abstract

The invention provides an engine-driven compressor and an operation control method thereof, which can reduce the load at the early stage of starting and can avoid the pressure rise at the early stage when overshoot occurs. The engine starting device is provided with a first bypass flow path and a second bypass flow path which bypass a pressure regulating valve provided in an intake air regulating device of a compressor main body and communicate a receiver tank with a valve-closed pressure receiving chamber of the intake air regulating valve, and a bleed air flow path which exhausts the valve-closed pressure receiving chamber, wherein an NO type first electromagnetic valve is provided in the first bypass flow path, and an NC type second electromagnetic valve is provided in the second bypass flow path, and the engine starting device starts the engine by non-energizing (opening) the first electromagnetic valve until a predetermined starting operation cancellation condition is satisfied. In a normal operation in which the intake air adjustment device performs the intake air control, when the pressure in the receiving container becomes equal to or higher than the overshoot pressure, the second solenoid valve is energized (opened) while the first solenoid valve is maintained in the energized (closed) state, and the overshoot avoidance operation is performed.

Description

Engine-driven compressor and operation control method thereof

Technical Field

The present invention relates to an operation control method of an engine-driven compressor and an engine-driven compressor for performing the operation control method, and more particularly, to an operation control method of an engine-driven compressor capable of reducing a start load, avoiding overshoot, and the like, and an engine-driven compressor for performing the operation control method.

Background

An engine-driven compressor including an engine such as a diesel engine as a drive source for driving a compressor main body is widely used for outdoor work such as civil work sites and construction sites where it is difficult to secure a power source.

As an example of such an engine-driven compressor, fig. 8 shows a structural example of an engine-driven compressor 300 provided with an oil-cooled compressor main body 340, and the oil-cooled compressor main body 340 compresses compressed gas and lubricating oil together and discharges the compressed gas as a gas-liquid mixed fluid.

The engine-driven compressor 300 is configured to: in addition to the compressor main body 340 and the engine 350, the present invention further includes a receiving tank 360, the receiving tank 360 separating the lubricating oil discharged together with the compressed gas from the compressor main body 340, and the compressed gas from which the lubricating oil has been separated in the receiving tank 360 is supplied to a consumption side to which an air working machine or the like, not shown, is connected after further removing oil components by an oil separator 366. The engine-driven compressor 300 is provided with an oil supply passage 364, and the oil supply passage 364 supplies the lubricating oil collected in the receiving container 360 to the compressor body 340 via the oil cooler 363 and the oil filter 367.

In the engine-driven compressor 300, an intake air adjusting device 310 is provided to supply a compressed gas having a stable pressure to a consumption side, and the intake air adjusting device 310 adjusts the intake air amount of the compressor main body 340 in accordance with the discharge-side pressure of the compressor main body 340, that is, the pressure in the receiving container 360 in the illustrated structure.

In the engine-driven compressor 300 shown in fig. 8, as the intake air adjustment device 310, an intake air adjustment valve 311 that opens and closes an intake port 341 of a compressor main body 340 and an unloading regulator 316 that controls opening and closing of the intake air adjustment valve 311 are provided, the unloading regulator 316 communicates with the receiver tank 360 via a control flow path 312, and compressed gas in the receiver tank 360 can be introduced into the unloading regulator 316 as an operating pressure for closing the intake air adjustment valve 311, and a pressure adjustment valve 313 is provided, and when the pressure in the receiver tank 360 is equal to or higher than a predetermined rated pressure, the control flow path 312 is opened by the pressure adjustment valve 313.

Further, reference numeral 314 in fig. 8 denotes an air bleeding flow path configured to: when the pressure regulating valve 313 closes the control flow path 312 and stops introducing the compressed gas into the unloading regulator 316, the compressed gas in the pressure receiving chamber of the unloading regulator 316 is discharged through the orifice 315, and the unloading regulator 316 can be returned to the fully open position by the biasing force of the return spring (not shown).

By providing the suction adjustment device 310 configured as described above, suction adjustment of the compressor main body 340 is performed in the following manner: if the pressure in the receiver tank 360 becomes equal to or higher than the rated pressure, the compressed gas in the receiver tank 360 starts to be introduced into the unloader regulator 316, the intake adjustment valve 311 throttles the intake port 341 of the compressor main body 340 or closes the intake port 341, and if the pressure in the receiver tank 360 decreases to be lower than the rated pressure, the intake adjustment valve 311 opens the intake port 341 of the compressor main body 340, and the pressure in the receiver tank 360 approaches the rated pressure.

In the engine-driven compressor 300 configured as described above, the engine 350, which is the drive source of the compressor main body 340, has a small torque in a low rotation speed range and is likely to be stopped (stalled) if it receives a load at the time of starting.

On the other hand, in the engine-driven compressor 300, the compressor body 340, which is the load of the engine 350, is directly coupled to the engine 350, and the engine 350 receives the load accompanying the rotation of the compressor body 340 from the start of the start, so if the load received from the compressor body 340 at the start of the engine 350 can be reduced, the engine 350 can be smoothly started.

Focusing on the structure of the engine-driven compressor 300, patent document 1 described later discloses a structure provided with a start load reducing device denoted by reference numeral 320 in fig. 8 in order to reduce a load applied to the engine 350 at the time of start.

The startup load reduction device 320 is configured by a bypass flow path 321 that bypasses the pressure adjustment valve 313 to communicate between the unloading regulator 316 and the receiving tank 360, and a bypass valve 325 that opens and closes the bypass flow path 321, and is configured such that: at the time of startup, the bypass valve 325 is operated to open the bypass flow path 321, thereby allowing the unloading regulator 316 to communicate directly with the receiver tank 360 without communicating with the receiver tank 360 via the pressure regulating valve 313.

As a result, if the compressor main body 340 starts rotating by the start of the engine 350 and the pressure in the receiver tank 360 rises, the unloading adjuster 316 operates to close the intake air adjustment valve 311 and shift the compressor main body 340 to the no-load operation, thereby reducing the load applied to the engine 350 at the start of the start.

After the operating state of the engine 350 is stabilized, the bypass valve 325 provided in the starting load reducing device 320 is operated to close the bypass flow path 321, and the pressure regulating valve 313 is returned to the normal operation of opening and closing the control flow path 312 in accordance with the pressure in the receiver tank 360, thereby enabling the known intake air adjustment.

Further, patent document 1 discloses a structure in which a manual on-off valve is provided as the bypass valve 325, but an engine-driven compressor has also been proposed in which the operation of opening and closing the bypass valve 325 can be electrically controlled based on the detected operating state of the engine by changing the manual on-off valve to an electromagnetic valve (see patent document 2).

Further, in a structure in which the bypass valve 325 is constituted by an electromagnetic valve and opening and closing thereof can be electrically controlled, the above-described starting load reduction device 320 is provided with a function other than the function of reducing the starting load, and as an example, in the example shown in fig. 9, the following points are the same as the example of fig. 8: when the engine is started, the bypass valve 325 is opened and the intake air adjustment valve 311 is closed to reduce the starting load ((a) of fig. 9), and if the engine is operating stably, the bypass valve 325 is closed to perform a normal operation in which the pressure adjustment valve 313 opens and closes the control flow path 312 in accordance with the pressure in the receiver tank 360 ((B) of fig. 9). However, when there occurs a so-called "overshoot" in which the pressure in the receiver tank 360 excessively increases with respect to the rated pressure due to the pressure adjustment valve 313 failing to perform the valve closing operation of the intake adjustment valve 311, the system also has a function as a safety device (see fig. 9C), specifically, the system opens the bypass valve 325 to close the intake adjustment valve 311, and discharges the compressed gas in the receiver tank 360 through the bypass flow path 321 and the bleed flow path 314 to reduce the pressure in the receiver tank 360 to avoid the overshoot. Further, the bypass valve 325 can also function as a purge mechanism (fig. 9 (a), opening the bypass valve 325 when the engine-driven compressor 300 is stopped, thereby discharging the compressed gas in the receiver tank 360 via the bypass flow path 321 and the bleed air flow path 314.

Patent document 1: japanese laid-open patent publication No. 2002-

Patent document 2: japanese patent laid-open publication No. 2017-115598

As the operation form of the solenoid valve, there are a normally open type (NO type) solenoid valve and a normally closed type (NC type) solenoid valve, wherein the normally open type (NO type) solenoid valve means: the valve body is separated from the valve seat by the biasing force of the return spring and is in an open state when not energized, and is seated on the valve seat by energization of the solenoid to close the valve. The Normally Closed (NC) type solenoid valve is: the valve element, which is seated on the valve seat by the biasing force of the return spring and is in a valve-closed state when not energized, is opened by being separated from the valve seat by energization of the solenoid.

According to the solenoid valve, the valve element urged by the return spring when the solenoid is energized is driven by the force generated by the solenoid when the solenoid is energized, and the valve element is opened and closed, so that a larger valve element driving force can be obtained when the valve element is driven by the solenoid when the solenoid is energized.

In addition, in the case of a solenoid valve having a structure in which a valve body is normally seated on a valve seat from the primary side, because a force is generated in a direction in which the valve body is intended to be pressed against the valve seat when the valve is closed due to a pressure difference between the primary pressure and the secondary pressure of the solenoid valve when the valve is closed, a larger driving force is required to move the valve body in order to open the valve in a closed state than to close the valve in an open state.

As a result, a Normally Closed (NC) type solenoid valve, which performs a valve opening operation requiring a large driving force by a solenoid, has a larger maximum operating pressure difference (the maximum value of the difference between the primary pressure and the secondary pressure that can operate the solenoid valve) than a Normally Open (NO) type solenoid valve.

As described with reference to fig. 9 a, when the bypass valve 325 is formed of an electromagnetic valve and the bypass valve 325 and the bypass flow path 321 function as not only the starting load reducing device 320 but also a purge means for discharging the compressed gas in the receiver tank 360 when the engine-driven compressor 300 is stopped, the bypass valve 325 needs to be opened and purged in a non-energized state in which the main power supply of the engine-driven compressor 300 is shut off by using a normally open (NO type) electromagnetic valve.

In this way, when the start load reducing device 320 has a purge function of discharging the compressed gas in the receiver tank 360 when the engine-driven compressor 300 is stopped, the bypass valve 325 must be a Normally Open (NO) type solenoid valve, but the Normally Open (NO) type solenoid valve has a low maximum operating pressure difference as described above, and therefore, when an overshoot occurs in which the pressure in the receiver tank 360 excessively rises above the rated pressure, that is, when the difference between the primary pressure and the secondary pressure of the bypass valve 325 is increasing, the bypass valve 325 cannot be opened even when the energization is stopped.

Therefore, when the bypass valve 325 is a Normally Open (NO) type solenoid valve, the start load reducing device 320 cannot be directly caused to perform the overshoot avoidance operation described with reference to (C) of fig. 9, and it is necessary to provide a pressure reducing valve 326 on the primary side of the bypass valve 325 as shown in fig. 9, and to reduce the pressure difference between the primary side pressure and the secondary side pressure of the bypass valve 325 at the time of occurrence of the overshoot to be equal to or less than the maximum operating pressure difference of the bypass valve 325 that is the Normally Open (NO) type solenoid valve.

The specification of the pressure reducing valve 326 also includes the use pressure and the use temperature range, and the high pressure reducing valve is difficult to be purchased and expensive.

Disclosure of Invention

Accordingly, the present invention has been made to overcome the drawbacks of the engine-driven compressor described with reference to fig. 9, and an object thereof is to provide an operation control method of an engine-driven compressor and an engine-driven compressor for executing the operation control method, in which the valve closing of an intake air adjusting valve can be completed early after the start of the engine, the load applied to the engine immediately after the start of the engine can be reduced, a no-load operation can be started early when an overshoot occurs without providing a pressure reducing valve, and the discharge of compressed gas in a receiver tank can be suppressed as low as possible when the overshoot occurs, and the pressure rise in the receiver tank can be suppressed as low as possible.

Hereinafter, reference numerals used in the detailed description will be described in the summary of the invention. The reference numerals are used to clarify the correspondence between the description of the claims and the description of the embodiments, and are not used to limit the technical scope of the present invention.

In order to achieve the above object, an operation control method of an engine-driven compressor according to the present invention is a method of controlling an operation of an engine-driven compressor including an engine (not shown), a compressor body 40 driven by the engine, and an intake air adjusting device 10 controlling an intake air to the compressor body 40, the intake air adjusting device 10 including: an intake regulating valve 11 that opens and closes an intake port 41 of the compressor body 40; a control flow path 12 for communicating the valve-closed pressure receiving chamber 113 of the intake air adjustment valve 11 with the discharge side (the receiving container 60 in the illustrated embodiment) of the compressor body 40; and a pressure regulating valve 13 that opens the control flow path 12 when a discharge-side pressure of the compressor body 40 is equal to or higher than a predetermined rated pressure, and closes the control flow path 12 when the discharge-side pressure of the compressor body 40 is lower than the rated pressure, wherein the engine-driven compressor 1 is provided with: a first bypass passage 21 and a second bypass passage 22 that bypass the pressure regulating valve 13 and communicate the discharge side (receiving container 60) of the compressor body 40 and a valve-closed pressure receiving chamber 113 of the intake regulating valve 11, respectively; a bleed air flow path 14 for throttling and discharging the compressed gas in the closed-valve pressure receiving chamber 113 of the intake air adjustment valve 11; a first solenoid valve 23 that opens and closes the first bypass passage 21; and a second solenoid valve 24 that opens and closes the second bypass flow path 22, that sets the first solenoid valve 23 as a Normally Open (NO) type solenoid valve, that sets the second solenoid valve 24 as a Normally Closed (NC) type solenoid valve having a maximum operating pressure difference higher than a maximum pressure difference that can be generated between the primary side and the secondary side of the second solenoid valve 24, that performs a starting operation for starting the engine in a state where the first solenoid valve 23 is not energized (opened), that, after the engine is started, when a predetermined starting operation release condition is satisfied, that causes the first solenoid valve 23 to be energized (closed) and the second solenoid valve 24 to be not energized (closed) to stop the starting operation, that shifts to a normal operation for performing air intake control by the air intake adjustment device 10, and that, in the normal operation, when a pressure on a discharge side (in the receiving container 60) of the compressor main body 40 becomes higher than the rated pressure by a predetermined amount than the rated pressure When the force (P1) is equal to or greater than the force (P1), the second solenoid valve 24 is energized (opened) while the first solenoid valve 23 is maintained in the energized (closed) state, and the overshoot-avoiding operation is performed, which shifts to the no-load operation in which the intake air adjustment valve 11 is closed.

Preferably, in the above operation control method, the operation control method includes: in the overshoot-avoiding operation, when the pressure on the discharge side (in the receiving container 60) of the compressor main body is lower than the overshoot pressure (P1) by a predetermined low pressure and is equal to or lower than the recovery pressure (P2) higher than the rated pressure, the second solenoid valve is de-energized (closed), the overshoot-avoiding operation is terminated, and the normal operation is resumed.

Preferably, the second solenoid valve 24 is energized (opened) during the startup operation.

Further, it is preferable that: the engine-driven compressor 1 is provided with a purge switch 71, and starts a purge operation in which the first electromagnetic valve 23 is not energized (thereby, the first electromagnetic valve 23 is opened and the second electromagnetic valve 24 is energized (opened) under a condition that "the pressure difference between the primary side and the secondary side of the first electromagnetic valve 23 is less than or equal to the maximum operating pressure difference of the first electromagnetic valve 23") by conduction of the purge switch 71, and the purge operation is ended and returned to the normal operation by energizing (closing) the first electromagnetic valve 23 and deenergizing (closing) the second electromagnetic valve 24 by disconnection of the purge switch 71.

Further, it is preferable that: when the main switch 70 is turned off, the first solenoid valve 23 is deenergized (thereby, the first solenoid valve 23 is opened under a condition that "the pressure difference between the primary side and the secondary side of the first solenoid valve 23 is smaller than or equal to the maximum operating pressure difference of the first solenoid valve 23"), the second solenoid valve 24 is energized (opened) to continue the operation of the engine, and a predetermined termination condition (for example, any one or a combination of a plurality of conditions of a predetermined time, the temperature of the cooling water of the engine, or the discharge temperature of the compressor body 40 being reduced to a predetermined temperature or lower) is satisfied, the second solenoid valve 24 is deenergized (closed), and the engine is stopped to terminate the cooling operation.

Further, an engine-driven compressor 1 according to the present invention is an engine-driven compressor including an engine (not shown), a compressor main body 40 driven by the engine, and an intake air adjusting device 10 for controlling an intake air to the compressor main body 40, the intake air adjusting device 10 including: an intake regulating valve 11 that opens and closes an intake port 41 of the compressor body 40; a control flow path 12 for communicating the valve-closed pressure receiving chamber 113 of the intake air adjustment valve 11 with the discharge side (the receiving container 60 in the illustrated embodiment) of the compressor body 40; and a pressure regulating valve 13 that opens the control flow path 12 when a discharge-side pressure of the compressor body 40 is equal to or higher than a predetermined rated pressure, and closes the control flow path 12 when the discharge-side pressure of the compressor body 40 is lower than the rated pressure, wherein the engine-driven compressor 1 is provided with: a first bypass passage 21 and a second bypass passage 22 that bypass the pressure regulating valve 13 and communicate the discharge side (receiving container 60) of the compressor body 40 and a valve-closed pressure receiving chamber 113 of the intake regulating valve 11, respectively; a bleed air flow path 14 for throttling and discharging the compressed gas in the closed-valve pressure receiving chamber 113 of the intake air adjustment valve 11; a first solenoid valve 23 that opens and closes the first bypass passage 21; a second solenoid valve 24 that opens and closes the second bypass passage 22; and a controller 30 that switches an operation state by controlling energization of the first solenoid valve 23 and the second solenoid valve 24, wherein the first solenoid valve 23 is a Normally Open (NO) type solenoid valve, and the second solenoid valve 24 is a Normally Closed (NC) type solenoid valve having a maximum operating pressure difference higher than a maximum pressure difference that can be generated between a primary side and a secondary side of the second solenoid valve 24, the controller 30 being configured to: a start operation is performed to start the engine in a state where the first electromagnetic valve 23 is not energized (opened), when a predetermined startup operation cancellation condition is satisfied after the engine is started, the first solenoid valve 23 is energized (closed) and the second solenoid valve 24 is de-energized (closed) to stop the startup operation, and the operation is shifted to a normal operation in which the intake air adjustment device 10 performs intake air control, in the normal operation, when the pressure on the discharge side of the compressor body 40 (in the receiving container 60) is equal to or higher than a predetermined high overpressure force (P1) with respect to the rated pressure, in a state where the first solenoid valve 23 is maintained in an energized (closed) state, the second solenoid valve 24 is energized (opened), and the overshoot-avoiding operation is shifted to the no-load operation in which the intake air adjustment valve 11 is closed.

In the engine-driven compressor 1 configured as described above, it is possible to configure: in the overshoot-avoiding operation, when the pressure on the discharge side (in the receiving container 60) of the compressor body 40 becomes a predetermined low pressure with respect to the overshoot pressure (P1) and becomes equal to or lower than the recovery pressure (P2) higher than the rated pressure, the controller 30 turns off (closes) the second electromagnetic valve 24, ends the overshoot-avoiding operation, and returns to the normal operation.

Further, it is preferable that: the controller 30 energizes (opens) the second solenoid valve 24 during the startup operation.

Further, it is preferable that: in the structure in which the purge switch 71 is provided in the engine-driven compressor 1, the controller 30 starts the purge operation in which the first electromagnetic valve 23 is not energized by conduction of the purge switch 71 (thereby, the first electromagnetic valve 23 is opened and the second electromagnetic valve 24 is energized (opened) under the condition that "the pressure difference between the primary side and the secondary side of the first electromagnetic valve 23 is less than or equal to the maximum operating pressure difference of the first electromagnetic valve 23"), and ends the purge operation by energizing (closing) the first electromagnetic valve 23 and deenergizing (closing) the second electromagnetic valve 24 by interruption of the purge switch 71, and returns to the normal operation.

Further, it is preferable that: the controller 30 performs a cooling operation in which the first solenoid valve 23 is deenergized (thereby opening the first solenoid valve 23 under a condition that "the pressure difference between the primary side and the secondary side of the first solenoid valve 23 is equal to or less than the maximum operating pressure difference of the first solenoid valve 23") by turning off the main switch 70, and the second solenoid valve 24 is energized (opened) to continue the operation of the engine, and when a predetermined termination condition (for example, any one or a combination of a plurality of conditions among a predetermined time, a cooling water temperature of the engine, a discharge temperature of the compressor body 40 which is reduced to a predetermined temperature or less) is satisfied, the second solenoid valve 24 is deenergized (closed), and the engine is stopped to terminate the cooling operation.

According to the configuration of the present invention described above, in the engine-driven compressor 1 that executes the operation control method of the present invention, the following significant effects can be obtained.

A first bypass flow path 21 and a second bypass flow path 22 that bypass the pressure regulating valve 13 are provided, the second bypass flow path 22 employs a Normally Closed (NC) type electromagnetic valve as the second electromagnetic valve 24 that opens and closes the second bypass flow path 22, the maximum operating pressure difference of the Normally Closed (NC) type electromagnetic valve is larger than the maximum pressure difference that can be generated between the primary side and the secondary side of the second electromagnetic valve, and when an overshoot occurs, the intake air regulating valve 11 can be closed and shifted to an overshoot avoidance operation by opening the second electromagnetic valve 24, so that when an overshoot occurs in which the difference between the primary side pressure and the secondary side pressure of the first electromagnetic valve 23 can become maximum, there is NO need to perform a valve opening operation on the first electromagnetic valve 23, and as a result, the following Normally Open (NO) type electromagnetic valve can be employed as the first electromagnetic valve 23 provided in the first bypass flow path 21, this Normally Open (NO) type solenoid valve has only the highest operating pressure difference smaller than the maximum pressure difference that can be generated between the primary side and the secondary side of the first solenoid valve 23, and even when such a Normally Open (NO) type solenoid valve is used, it is not necessary to provide a pressure reducing valve on the primary side of the first solenoid valve 23.

As a result, although the control for shifting to the NO-load operation is performed when the overshoot occurs, if the energization of the first electromagnetic valve 23 is stopped when the engine-driven compressor 1 is stopped (when the main power supply is turned off), the first electromagnetic valve 23 is opened, and the compressed gas in the receiver tank 60 can be discharged (purged), so that the advantage of using the Normally Open (NO) type electromagnetic valve described above can be enjoyed without providing an expensive pressure reducing valve.

Further, even during the overshoot-avoiding operation, the discharge-side pressure of the compressor body 40 (the pressure in the receiver tank 60) is introduced into the valve-closed pressure-receiving chamber 113 of the intake air adjustment valve 11 via the second bypass passage 22, so that if the discharge-side pressure of the compressor body 40 (the pressure in the receiver tank 60) becomes equal to or higher than the overshoot pressure P1 and the second electromagnetic valve 24 is opened by energization, the intake air adjustment valve 11 closes in a relatively short time to stop the compressor body 40 from generating compressed gas, and further increase in the discharge-side pressure of the compressor body 40 (the pressure in the receiver tank 60) at the time of occurrence of overshoot can be stopped early, whereby the peak pressure (Pmax) of the receiver tank 60 at the time of occurrence of overshoot can be suppressed low.

In the case where the second solenoid valve 24 is also energized (opened) to open the second solenoid valve 24 during the start-up operation, the working pressure is introduced into the valve-closing pressure receiving chamber 113 of the intake adjustment valve 11 from both the systems at the same time, and the bore of the Normally Closed (NC) type second solenoid valve 24 is normally larger than the bore of the Normally Open (NO) type first solenoid valve 23 to increase the flow passage area, whereby the valve-closing operation of the intake adjustment valve 11 during the engine start-up operation can be completed earlier.

The engine-driven compressor 1 is provided with a purge switch 71, and in a structure in which the first electromagnetic valve 23 is not energized (thereby, the first electromagnetic valve 23 is opened under a condition that "the pressure difference between the primary side and the secondary side of the first electromagnetic valve 23 is not more than the maximum operating pressure difference of the first electromagnetic valve 23") by conduction of the purge switch 71, and the second electromagnetic valve 24 is energized (opened), the operator can shift to a purge operation performed while discharging the discharge-side pressure of the compressor main body (the pressure in the receiving container 60) in a no-load operation state in which the intake adjustment valve 11 is closed, by operating the purge switch 71 as necessary.

In particular, since the Normally Closed (NC) type second solenoid valve 24 is generally larger in bore size and larger in flow passage area than the Normally Open (NO) type solenoid valve, the pressure on the discharge side (inside the receiver tank 60) of the compressor body 40 can be reduced at an early stage by performing such air discharge (purge) through the second bypass flow passage 22.

Further, the engine-driven compressor 1 is configured to: by turning off the main switch 70, the first solenoid valve 23 is not energized (thereby, under the condition that "the pressure difference between the primary side and the secondary side of the first solenoid valve 23 is less than or equal to the maximum operating pressure difference of the first solenoid valve 23", the first solenoid valve 23 is opened), the second solenoid valve 24 is energized (opened), and the cooling operation in which the engine is continuously operated in the no-load state in which the intake adjustment valve 11 is closed is performed, whereby the cooling operation of the engine is performed while the compressed gas on the discharge side (inside the receiving container 60) of the compressor body 40 is exhausted in the no-load state in which the intake adjustment valve 11 is closed, and the aforementioned cooling operation can be performed in a state in which the load applied to the engine is reduced as much as possible.

Drawings

Fig. 1 is an explanatory view of an overall configuration of an engine-driven compressor of the present invention.

Fig. 2 is a sectional view showing one example of the structure of the suction adjustment valve.

Fig. 3 is an explanatory view of essential parts of the engine-driven compressor of the present invention, where (a) is an explanatory view during the start-up operation, (B) is an explanatory view during the normal operation, and (C) is an explanatory view during the overshoot-avoidance operation.

Fig. 4 is an explanatory view of a main part of the engine-driven compressor of the present invention, where (a) is an explanatory view at the time of the purge operation and the stop operation, and (B) is an explanatory view at the time of the cooling operation.

Fig. 5 is a functional block diagram of the engine driven compressor of the present invention.

Fig. 6 is a timing chart showing operations of each part in the starting operation, the normal operation, and the overshoot-avoiding operation of the engine driven compressor according to the present invention.

Fig. 7 is a timing chart showing operations of each part from the purge operation to the stop of the engine-driven compressor according to the present invention.

Fig. 8 is an explanatory diagram of a conventional engine-driven compressor provided with a start-up load reducing device (corresponding to patent document 1).

Fig. 9 is an explanatory view of an engine-driven compressor in which a start-up load reduction device is provided with an overshoot avoidance function and a purge function at the time of stopping, (a) is an explanatory view showing operations of each part at the time of start-up operation and at the time of stopping, (B) is an explanatory view showing operations of each part at the time of normal operation, and (C) is an explanatory view showing operations of each part at the time of occurrence of overshoot.

Description of the reference numerals

1 engine-driven compressor

10 air suction adjusting device

11 air intake adjusting valve

111 body (valve box)

112 airtight chamber (jar)

113 closed pressure receiving chamber

114 auxiliary pressure receiving chamber (spring chamber)

114a spring

115 suction flow path

115a valve seat

116 valve body

116a valve shaft

117 sleeve

118 end plate

119 pressure body (piston)

12 control flow path

13 pressure regulating valve

14 bleed air flow path

15 throttling part

21 first bypass flow path

22 second bypass flow path

23 first solenoid valve (normally open (NO) type)

24 second solenoid valve (normally closed (NC) type)

25 shared flow path

26 divergence block

27 three-way electromagnetic valve

28a to 28c flow path

30 controller

36 timer

40 compressor body

41 air inlet

51 temperature sensor

60 receiving container

61 pressure regulating valve

62 discharge flow path

63 oil cooler

64 oil supply flow path

65 pressure sensor

66 service valve

70 main switch

71 purge switch

72 starting switch

300 engine driving compressor

310 air suction adjusting device

311 air intake adjusting valve

312 control flow path

313 pressure regulating valve

314 bleed air flow path

315 throttle part

316 unloading adjuster

320 starting load reducing device

321 bypass flow path

325 bypass valve

326 pressure reducing valve

340 compressor main body

341 air inlet

350 engine

360 receiving container

363 oil cooler

364 oil supply flow path

366 oil separator

367 oil filter

Detailed Description

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

(integral construction of Engine-driven compressor)

Reference numeral 1 in fig. 1 denotes an engine-driven compressor of the present invention, and the engine-driven compressor 1 includes a compressor main body 40, an engine (not shown) that drives the compressor main body 40, and a receiver tank 60 that stores compressed gas discharged from the compressor main body 40, and is configured to be capable of storing the compressed gas discharged from the compressor main body 40 in the receiver tank 60 and thereafter supplying the compressed gas to an air working machine, not shown, connected to an inspection valve 66 via a pressure regulating valve 61.

In the present embodiment, the compressor body 40 is an oil-cooled screw compressor that compresses compressed gas together with lubricating oil for lubrication, cooling, and sealing, and is configured such that a gas-liquid mixed fluid of the compressed gas and the lubricating oil is discharged, the compressed gas is introduced into the receiver tank 60 through the discharge flow path 62, the lubricating oil can be separated in the receiver tank 60, and an oil supply flow path 64 is provided, the oil supply flow path 64 supplying the lubricating oil recovered in the receiver tank 60 to the compressor body 40 again through the oil cooler 63.

However, the compressor body 40 mounted on the engine-driven compressor 1 which is the subject of the present invention is not limited to the oil-cooled compressor body, and an oil-less compressor body which does not require lubricating oil for compressing the compressed gas may be mounted, and in this case, the receiving container 60 described above, the oil supply passage 64 for supplying the lubricating oil collected in the receiving container 60 to the compressor body 40, and the like may be omitted.

(suction adjusting device)

The engine-driven compressor 1 configured as described above is similar to the structure of the conventional engine-driven compressor described with reference to fig. 8 in that the air intake adjusting device 10 performs air intake adjustment in which the air intake port 41 of the compressor body 40 is throttled or closed if the secondary pressure of the compressor body 40, that is, the pressure in the receiver tank 60 in the present embodiment becomes equal to or higher than a predetermined rated pressure, and the air intake port 41 of the compressor body 40 is fully opened so that the pressure in the receiver tank 60 approaches the predetermined rated pressure if the pressure in the receiver tank 60 is lower than the rated pressure.

The configuration of the intake air adjustment device 10 including the intake air adjustment valve 11, the control flow path 12, and the pressure adjustment valve 13 and the configuration including the bleed air flow path 14 are the same as those of the engine-driven compressor described with reference to fig. 8, wherein the air intake regulating valve 11 controls the opening and closing of the air intake 41 of the compressor body 40, in the illustrated example, the control flow path 12 is a Normally Open (NO) type intake air adjusting valve, and communicates the closed valve pressure receiving chamber 113 of the intake air adjusting valve 11 with the discharge side (receiver tank 60) of the compressor body 40, and the pressure adjusting valve 13 is configured to adjust the pressure of the refrigerant in the receiver tank 60, the control flow path 12 is opened when the pressure in the receiving container 60 is equal to or higher than a predetermined rated pressure, when the pressure in the receiving container 60 is lower than the rated pressure, the control flow path 12 is closed, and the bleed flow path 14 discharges the compressed gas in the closed-valve pressure receiving chamber 113 through the throttle section 15.

(suction adjusting valve)

The intake adjustment valve 11 constituting the intake adjustment device 10 opens and closes the intake port 41 of the compressor body 40 as described above, and in the present embodiment, the intake adjustment valve 11 shown in fig. 2 is used as an example.

The intake air adjustment valve 11 shown in fig. 2 is configured such that: an intake flow path 115 through which compressed gas passes is formed by a space formed in the body (valve box) 111, and the intake flow path 115 can be closed by seating a valve body 116 on a valve seat 115a provided in the intake flow path 115.

The valve body 116 is a so-called "umbrella valve" in which a valve shaft 116a is attached to a disk-shaped valve body 116, and is configured such that: in a state where the valve shaft 116a is inserted into a cylindrical sleeve 117 formed in the body 111, the valve body 116 is moved forward and backward along the axial direction of the sleeve 117, whereby the valve body 116 can be moved between a valve-closed position seated on the valve seat 115a and a valve-open position separated from the valve seat 115 a.

In order to enable such movement of the valve body 116, the cylinder 112 communicating with the suction flow channel 115 via the sleeve 117 is formed coaxially with the sleeve 117 in the valve housing 111 of the intake adjustment valve 11.

The cylinder 112 is constituted such that: in a state where the valve shaft 116a is inserted into the sleeve 117, an end portion on the opposite side to the formation side of the sleeve 117 is closed by an end plate 118 to form an airtight chamber, and the inside of the airtight chamber (cylinder) 112 is divided into two chambers by a pressure receiving body 119 connected to the other end of the valve shaft 116a, that is, a piston of the present embodiment, whereby a valve closing pressure receiving chamber 113 of the intake adjustment valve 11 is formed on the end plate 118 side, and an auxiliary pressure receiving chamber 114 is formed on the opposite side to the valve closing pressure receiving chamber 113 through the piston 119.

In the illustrated structure, in order to make the intake adjustment valve 11 Normally Open (NO), the spring 114a that presses the piston 119 toward the valve-closed pressure receiving chamber 113 side is housed in the aforementioned auxiliary pressure receiving chamber 114, and the auxiliary pressure receiving chamber 114 is made to function as a spring chamber, but the spring 114a is not necessarily provided in the auxiliary pressure receiving chamber 114 as long as the intake adjustment valve 11 can be made normally open.

In the illustrated structure, not only the valve body 116 and the valve seat 115a are provided in the common body (valve housing) 111, but also the cylinder 112 and the piston 119 for moving the valve body 116 forward and backward are provided in the common body (valve housing) 111, but a structure may be adopted in which driving mechanisms such as an intake adjustment valve body not provided with a valve body driving mechanism and an unloading adjuster for driving the valve body of the intake adjustment valve body are separately provided, as in the conventional engine-driven compressor described with reference to fig. 8, and in this case, the valve-closing pressure receiving chamber 113, the auxiliary pressure receiving chamber 114, and the pressure receiving body 119 described above are formed in the unloading adjuster.

In the illustrated embodiment, the piston 119 that moves upon receiving the pressure of the compressed gas introduced into the valve-closing pressure receiving chamber 113 is provided as the pressure receiving member to partition the inside of the cylinder 112, which is the airtight chamber of the drive mechanism of the valve body 116, but the pressure receiving member 119 is not limited to the piston described above, and may be a diaphragm or the like as the pressure receiving member 119, as long as the operation of the valve body 116 can be controlled by the compressed gas introduced into the valve-closing pressure receiving chamber 113.

(flow path for control)

The valve closing pressure receiving chamber 113 of the intake adjustment valve 11 configured as described above communicates with the first bypass passage 21 and the second bypass passage 22 (see fig. 1 to 4) in addition to the control passage 12 described above, and the valve closing pressure receiving chamber 113 of the intake adjustment valve 11 communicates with the discharge side (the receiver tank 60) of the compressor body 10 via the first bypass passage 21 and the second bypass passage 22 described above, and the intake adjustment valve 11 can be operated to close the valve using the pressure in the receiver tank 60 as the operating pressure.

The embodiment shown in fig. 1 shows the following configuration: the other end of the common flow path 25, one end of which communicates with the receiving container 60, is connected to and branched from a branching block 26 made of an aluminum alloy, one ends of the control flow path 12, the first bypass flow path 21, and the second bypass flow path 22 communicate with the branching block 26, and the other ends of the control flow path 12, the first bypass flow path 21, and the second bypass flow path 22 communicate with the valve closing pressure receiving chamber 113 of the intake air adjusting valve 11. However, one end of the control flow path 12, the first bypass flow path 21, and the second bypass flow path 22 may directly communicate with the receiver tank 60 as shown in fig. 3 and 4, without communicating with the receiver tank 60 via the above-described branching block 26 and the common flow path 25.

The first bypass passage 21 is provided with a first solenoid valve 23 for opening and closing the first bypass passage 21, and the second bypass passage 22 is provided with a second solenoid valve 24 for opening and closing the second bypass passage 22.

Among them, the first solenoid valve 23 is a Normally Open (NO) type solenoid valve, and the first solenoid valve 23 is not a solenoid valve that performs a valve opening operation when an overshoot occurs in which a large pressure difference occurs between the primary side and the secondary side, so that a solenoid valve can be employed in which the maximum operating pressure difference is lower than the maximum pressure difference that can occur between the primary side and the secondary side of the first solenoid valve 23 (a pressure difference at the time of valve closing when an overshoot occurs), and a structure can be formed in which a pressure reducing valve is not provided on the primary side of the first solenoid valve 23.

On the other hand, as the second solenoid valve 24 provided in the second bypass passage 22, a Normally Closed (NC) type solenoid valve is used, in which the maximum operating pressure difference is larger than the maximum pressure difference that can be generated between the primary side and the secondary side of the second solenoid valve 24 in the second bypass passage 22 (the pressure difference at the time of valve closing when overshoot occurs).

In fig. 1 to 3, reference numeral 27 denotes a three-way solenoid valve, and the C port of the three-way solenoid valve 27 is caused to communicate with an auxiliary pressure receiving chamber 114 (spring chamber) of the intake adjustment valve 11 via a flow path 28C, the flow path 28a attached to the a port is caused to communicate with an intake flow path 115 of the intake adjustment valve 11 on the secondary side of a valve seat 115a, and the flow path 28B attached to the B port is caused to communicate with the primary side of the intake adjustment valve 11, and is released into the atmosphere via an air cleaner (not shown) attached to the primary side of the intake adjustment valve 11.

Thereby, the structure is as follows: the auxiliary pressure receiving chamber 114 of the air intake adjustment valve 11 can be selectively communicated with the intake flow path 115 on the secondary side of the valve seat 115a and the primary side of the air intake adjustment valve 11 by switching of the three-way solenoid valve 27.

(switches, sensors, etc.)

The engine-driven compressor 1 of the present invention configured as described above is provided with a controller 30 (described later) that controls the operation of each part of the engine-driven compressor 1, and switches and sensors (see fig. 5) that output electric signals to the controller 30.

As the switches, switches for performing operations such as turning on/off of the main power supply of the engine-driven compressor 1, starting of the engine, and starting and stopping of the purge (for causing the controller 30 described later to perform) may be provided.

As an example, in the embodiment shown in fig. 5, a main switch 70, a start switch 72, and a purge switch 71 are provided as such switches on an operation panel of the engine-driven compressor 1.

The main switch 70 is configured to be capable of switching between "off" and "on" of the main power supply by being rotated.

The "off" is a stopped state in which the energization of each part of the engine-driven compressor 1 is stopped, and the "on" is a so-called "accessory position" in which the energization of the electronic control device such as the engine and the controller 30, various sensors, the measuring instruments, and the like is stopped.

The start switch 72 is a switch for starting the engine, and if the start switch 72 is pressed for a predetermined time (for example, 1 second) or longer, the starter motor of the engine is energized to start the engine.

In the structure of the engine-driven compressor 1 including the main switch 70 and the start switch 72, the structure is such that: after the main switch 70 is rotated from the "off" position to the "on" position, the engine is started by long pressing the start switch 72, so that the engine-driven compressor 1 can be started and continued, and if the main switch 70 is rotated from the "on" position to the "off" position, the engine-driven compressor 1 can be stopped.

The switch for starting and stopping the engine-driven compressor 1 is not limited to the structure in which the main switch 70 and the start switch 72 are provided separately as described above, and various structures can be employed as long as on/off of accessories (main switch) and on/off of the starter motor are possible, and the switch for on/off of accessories and on/off of the starter motor may be constituted by a known key switch or the like which can be switched from an off position to an on position (accessory position) and further to a start position for rotating the starter motor of the engine by inserting a key and rotating the key switch.

Further, reference numeral 71 in fig. 5 denotes a purge switch for instructing start and stop of discharge (purge) of the compressed gas in the receiver tank 60, and when the purge switch 71 is turned on, the controller 30 described later starts discharge of the compressed gas in the receiver tank 60 and stops the discharge by turning off the purge switch 71.

In the illustrated example, the purge switch 71 is constituted by an alternate switch, and is configured such that: the purge switch 71 in the off state is switched to on by one pressing operation, and is returned to off by further one pressing operation of the purge switch 71 from the on state.

However, the structure of the purge switch 71 is not limited to the illustrated example, and any of various known switches such as a toggle switch may be used as long as the on/off state can be switched.

The engine-driven compressor 1 of the present invention is provided with a pressure sensor 65 (fig. 1, 3 to 5) for detecting the pressure in the receiver tank 60, and the controller 30 monitors the pressure change in the receiver tank 60 based on a detection signal from the pressure sensor 65.

Further, the engine-driven compressor 1 of the present invention is provided with a temperature sensor 51 (fig. 1, 3 to 5) for detecting the discharge temperature of the compressor body 40, and the controller 30 monitors the change in the discharge temperature of the compressor body 40 based on a detection signal from the temperature sensor 51.

(controller)

The engine-driven compressor 1 according to the present invention configured as described above is provided with the controller 30 as an electronic control device, and the controller 30 controls the operations of the first electromagnetic valve 23, the second electromagnetic valve 24, and the three-way electromagnetic valve 27 described above based on the operations of the switches described above, the pressure change in the receiver tank 60 detected by the pressure sensor 65, and the change in the discharge temperature of the compressor main body 40 detected by the temperature sensor 51.

The controller 30 executes the following control based on the operation states of the

switches

70, 71, and 72, the pressure in the receiving container 60 detected by the pressure sensor 65, and the discharge temperature of the compressor body 40 detected by the temperature sensor 51.

(1) Starting operation

After the operator turns the main switch 70 to the "on" position (see T1 in fig. 6), if the start switch 72 is pressed one step further, the controller 30 turns on the second electromagnetic valve 24 by energizing (conducting) the second electromagnetic valve 24 while maintaining the first electromagnetic valve 23 in an open state, which is a non-energized state (disconnected state), and rotates the starter motor in this state to start the engine (T2 in fig. 6).

Thus, if the pressure in the receiver tank 60 rises due to the rotation of the compressor body 40 and becomes equal to or higher than the operating pressure of the intake adjustment valve 11, the intake adjustment valve 11 closes (T3 in fig. 6), the first electromagnetic valve 23, which is maintained in a non-energized (blocked) state as shown in fig. 3 a, is maintained in an open state, the second electromagnetic valve 24 is opened by energization (conduction), and the "start-up operation" of the engine is performed in a no-load state in which the intake adjustment valve 11 closes the intake port 41 of the compressor body 40 until a predetermined release condition is satisfied.

In the structure in which the three-way solenoid valve 27 shown in fig. 1 and 3 is provided, the controller 30 switches the three-way solenoid valve 27 to a position (a position at which the ports C-a communicate with each other) at which the auxiliary pressure receiving chamber 114 of the intake air adjusting valve 11 communicates with the intake flow path 115 on the secondary side of the valve seat 115a during the startup operation.

As a result, the auxiliary pressure receiving chamber 114 of the intake adjustment valve 11 can be made negative pressure at the time of engine startup, and thus the valve closing operation of the intake adjustment valve 11 at the time of engine startup can be completed earlier.

(2) Normal running

If the aforementioned cancellation condition of the startup operation is satisfied, the controller 30 switches the first solenoid valve 23 in the non-energized (off) state to the energized (on) state, and switches the second solenoid valve 24 in the energized (on) state to the non-energized (off) (T4 of fig. 6).

As a result, as shown in fig. 3 (B), both the first solenoid valve 23 and the second solenoid valve 24 are in the closed state, and the control flow path 12 and the pressure regulating valve 13 control the introduction of the operating pressure into the closed pressure receiving chamber 113 of the intake regulating valve 11, and the operation shifts to the "normal operation" in which the intake control of the compressor body 40 is performed.

In the present embodiment, the configuration is such that: when the discharge temperature of the compressor body 40 detected by the temperature sensor 51 at the start of the normal operation is lower than 60 ℃, the aforementioned "start operation" is stopped and the aforementioned "normal operation" is shifted to when any of the conditions that the detected temperature of the temperature sensor 51 reaches 60 ℃ and that 120 seconds have elapsed since the engine start is calculated by the timer 36 are satisfied, and when the discharge temperature of the compressor body detected by the temperature sensor 51 at the start of the normal operation is 60 ℃ or higher, the aforementioned "start operation" is stopped and the aforementioned "normal operation" is shifted to when 30 seconds have elapsed since the engine start is calculated by the timer 36.

During the transition to the normal operation, the pressure in the receiver tank 60 is still lower than the operating pressure of the pressure regulating valve 13, and the compressed gas is not introduced into the closed-valve pressure receiving chamber 113 of the intake regulating valve 11, so that the intake regulating valve 11 is opened (see fig. 3B and T4 of fig. 6), the compressor body 40 starts the compression of the intake gas, and the pressure in the receiver tank 60 rises.

Then, if the pressure in the receiver tank 60 rises to a predetermined rated pressure or more, the pressure regulating valve 13 is opened and the intake regulating valve 11 is closed, and if the pressure in the receiver tank 60 drops to a pressure lower than the rated pressure due to, for example, consumption of compressed gas on the consumption side, the pressure regulating valve 13 is closed and the intake regulating valve 11 is opened, and the compressor body 40 starts compression of the intake gas, and by repeating such operations, during normal operation, known intake control is performed so that the pressure of the compressed gas supplied to the consumption side approaches the rated pressure.

In addition, in the structure in which the three-way electromagnetic valve 27 shown in fig. 1 and 3 is provided, the controller 30 is configured to: during this normal operation, the three-way solenoid valve 27 is switched to a position at which the auxiliary pressure receiving chamber 114 of the air intake adjustment valve 11 communicates with the primary side of the air intake adjustment valve 11, whereby the auxiliary pressure receiving chamber 114 of the air intake adjustment valve 11 is released into the atmosphere, and the air intake adjustment valve 11 can be operated to open and close in accordance with a change in pressure in the receiver tank 60 introduced into the closed pressure receiving chamber 113.

(3) Overshoot avoidance operation

The controller 30 monitors the pressure in the receiver tank 60 based on the detection signal from the pressure sensor 65, and if the pressure in the receiver tank 60 becomes equal to or higher than the overshoot pressure (P1) set to a predetermined high pressure than the above-described rated pressure, the controller 30 switches the second solenoid valve 24 in the non-energized (disconnected) state to the energized (conducting) state while maintaining the first solenoid valve 23 in the energized (conducting) state (see T5 in fig. 6).

Thus, although the first solenoid valve 23 is kept closed, the second solenoid valve 24 is opened, and the compressed gas from the receiver tank 60 is introduced into the closed-valve pressure receiving chamber 113 of the intake adjustment valve 11, so that the opening of the second solenoid valve 24 is slightly delayed and the intake adjustment valve 11 is closed (T6 in fig. 6), and the overshoot avoidance operation is performed in the state where the first solenoid valve 23 is closed, the state where the second solenoid valve 24 is opened, and the state where the intake adjustment valve 11 is closed (see fig. 3 (C)).

In the structure in which the three-way solenoid valve 27 shown in fig. 1 and 3 is provided, the controller 30 switches the three-way solenoid valve 27 to a position at which the auxiliary pressure receiving chamber 114 of the intake adjustment valve 11 communicates with the primary side of the intake adjustment valve 11 and is released into the atmosphere during the overshoot-avoiding operation, which is similar to the normal operation of fig. 3 (B).

While the pressure in the receiver tank 60 slightly increases during the period from the transition to the overshoot-avoiding operation until the intake air adjustment valve 11 is closed (T5 to T6 in fig. 6), if the intake air adjustment valve 11 is closed (T6 in fig. 6), the compressor body 40 stops the intake air and does not discharge any more compressed gas, and the compressed gas in the receiver tank 60 is discharged through the second bypass passage 22 and the bleed passage 14, whereby the pressure in the receiver tank 60 can be prevented from further increasing.

Then, if the controller 30 determines that the pressure in the receiver tank 60 is lower than the overshoot pressure (P1) by a predetermined amount and is equal to or lower than the recovery pressure (P2) set to a pressure higher than the rated pressure based on the detection signal of the pressure sensor 65, the energization of the second solenoid valve 24 is stopped (T7 in fig. 6).

As a result, the second electromagnetic valve 24 is closed, and the engine-driven compressor 1 returns to the normal operation in which the opening and closing operations of the air-conditioning valve 11 are controlled by the control flow path 12 and the pressure adjustment valve 13 as shown in fig. 3 (B).

As described above, the engine-driven compressor 1 according to the present invention is configured such that: the second solenoid valve 24, which is a Normally Closed (NC) type solenoid valve having a high maximum operating pressure difference, is opened, whereby the intake adjustment valve 11 is closed and the compressed gas is discharged (purged) when an overshoot occurs. When the overshoot occurs, the first solenoid valve 23, which is a Normally Open (NO) type solenoid valve, is maintained in a closed state, so that it is not necessary to provide a pressure reducing valve on the primary side of the first solenoid valve 23.

(4) Purge operation

In the configuration in which the purge switch 71 is provided in the engine-driven compressor 1 as shown in fig. 5, the following "purge operation" can be performed: the operation is performed in a state where the intake adjustment valve 11 is closed by the on operation of the purge switch 71 by the operator and the compressed gas is discharged through the bleed air flow path 14.

The operator turns on the purge switch 71, and if the controller 30 receives an on signal from the purge switch 71, the first solenoid valve 23 in the energized (on) state is switched to the de-energized (off) state, and the second solenoid valve 24 in the de-energized (off) state is switched to the energized (on) state, and the purge operation is shifted to T8 in fig. 7.

Thereby, the second electromagnetic valve 24 of the Normally Closed (NC) type having a high highest working pressure difference is opened while being energized (conducted).

On the other hand, in the case where the pressure difference between the primary side and the secondary side when the purge switch 71 is turned on is higher than the maximum operating pressure difference, the first solenoid valve 23, which is a Normally Open (NO) type solenoid valve having a low maximum operating pressure difference, cannot immediately perform the actuation operation and maintains the closed state even if the purge switch 71 is turned on and is switched to the non-energized state (see fig. 4a and T8 of fig. 7).

However, when the compressed gas in the receiver tank 60 is introduced into the closed-valve pressure receiving chamber of the intake adjustment valve 11 through the second bypass passage 22 by opening the second solenoid valve 24 and the intake adjustment valve 11 is closed (maintained in the closed state in the illustrated example), the compressed gas in the receiver tank 60 is discharged through the second bypass passage 22 and the bleed passage 14 without discharging the compressed gas from the compressor body 40, and the pressure in the receiver tank 60 gradually decreases.

Then, if the pressure in the receiver tank 60 decreases and the difference between the primary pressure and the secondary pressure of the first electromagnetic valve 23 becomes equal to or less than the maximum operating pressure difference of the first electromagnetic valve 23, the first electromagnetic valve 23 opens (see T9 in fig. 7), and the compressed gas starts to be discharged through the first bypass flow path 21 and the bleed air flow path 14, whereby the pressure in the receiver tank 60 further decreases.

In addition, the structure in which the three-way solenoid valve 27 shown in fig. 1 and 3 is provided is the same as that in the normal operation of fig. 3 (B) in terms of: during this purge operation, the controller 30 switches the three-way solenoid valve 27 to a position at which the auxiliary pressure receiving chamber 114 of the intake adjustment valve 11 communicates with the primary side of the intake adjustment valve 11 and is released to the atmosphere.

From the state where the purge operation is performed, if the operator switches the purge switch 71 off, the controller switches the first solenoid valve 23 in the non-energized (off) state to the energized (on) state, switches the second solenoid valve 24 in the energized (on) state to the non-energized (off) state, and ends the purge operation (T10 in fig. 7).

Thereby, both the first solenoid valve 23 and the second solenoid valve 24 are closed, and the normal operation shown in fig. 3 (B) is resumed.

In the illustrated embodiment, the structure in which the "purge operation" is performed by the operator manually performing the on operation of the purge switch 71 has been described, but in addition to this structure, the controller 30 may automatically start the purge operation when a predetermined condition is satisfied regardless of the presence or absence of the operation of the purge switch 71.

In this case, the configuration may be such that: a detection means for detecting the time of the no-load operation for closing the suction control valve 11 and a maintenance pressure sensor for detecting the pressure supplied to the air working machine and the like are provided, and if it is detected that the no-load operation continues for a predetermined time (for example, 20 seconds), the controller 30 performs an "automatic purge operation" for automatically switching the first solenoid valve 23 to a non-energized (off) state and the second solenoid valve 24 in a non-energized (off) state to an energized (on) state, and ends the "automatic purge operation" in accordance with the detection of the maintenance pressure, closes both the first solenoid valve 23 and the second solenoid valve 24, and returns to the normal operation.

In the case where the controller 30 is capable of executing the "automatic purge operation" for automatically starting the purge operation without the operation of the purge switch 71 as described above, it may be configured to be able to change whether or not to cause the controller 30 to perform such a setting of the "automatic purge operation", and in this case, a means (for example, a touch panel or the like) for an operator to input such a setting change may be provided on the operation panel.

(5) Cooling operation

Further, the engine-driven compressor 1 is configured to: in the case where the engine is stopped after the main switch 70 is switched to the off position until a predetermined end condition is satisfied (in the present embodiment, a predetermined time has elapsed), and then the cooling operation is performed in which the operation of the engine is continued, if the main switch 70 is switched to the off position, the controller 30 switches the first solenoid valve 23 in the energized (conductive) state to the non-energized (off) state, and switches the second solenoid valve 24 in the non-energized (off) state to the energized (conductive) state, and shifts to the cooling operation (T11 in fig. 7).

As a result, the Normally Closed (NC) type second electromagnetic valve 24 having a high maximum operating pressure difference is opened while being energized (conducted), and as a result, the compressed gas introduced into the receiving container 60 through the valve-closed pressure receiving chamber 113 of the intake air regulating valve 11 closes (maintains the closed state) (T11 in fig. 7), and the compressed gas is not discharged from the compressor body 40, while the compressed gas in the receiving container 60 is discharged through the second bypass flow path 22 and the bleed air flow path 14, and the pressure in the receiving container 60 gradually decreases.

On the other hand, when the pressure difference between the primary side and the secondary side when the main switch 70 is turned off is higher than the maximum operating pressure difference, even if the first solenoid valve 23, which is a Normally Open (NO) type solenoid valve having a low maximum operating pressure difference, is switched to a non-energized state by the interruption of the main switch 70, the actuation operation cannot be immediately performed and the closed state is maintained (see T11 in fig. 7), the pressure in the receiver tank 60 decreases, the difference between the primary pressure and the secondary pressure of the first solenoid valve 23 becomes equal to or less than the maximum operating pressure difference of the first solenoid valve 23, and the valve opens (see T12 in fig. 7), as shown in fig. 4 (B), not only the compressed gas introduced into the closed-valve pressure-receiving chamber 113 of the intake air adjustment valve 11 via the second bypass passage 22 is discharged via the bleed passage 14, the compressed gas introduced into the closed-valve pressure-receiving chamber 113 through the first bypass passage 21 is also discharged through the bleed passage 14.

In addition, the structure in which the three-way solenoid valve 27 shown in fig. 1 and 3 is provided is the same as that in the normal operation of fig. 3 (B) in terms of: during this cooling operation, the controller 30 switches the three-way solenoid valve 27 to a position at which the auxiliary pressure receiving chamber 114 of the intake adjustment valve 11 communicates with the primary side of the intake adjustment valve 11 and is released to the atmosphere.

On the other hand, if the elapse of the predetermined time from the start of the cooling operation is counted by the timer 36, the controller 30 stops the engine and stops energizing the second electromagnetic valve 24 (T13 of fig. 7).

As a result, although the Normally Closed (NC) type second electromagnetic valve 24 is closed, the Normally Open (NO) type first electromagnetic valve is maintained in the open state, and the compressed gas in the receiver tank 60 continues to be discharged through the first bypass flow path 21 and the bleed air flow path 14, and the pressure in the receiver tank 60 decreases, so the pressure in the valve-closed pressure chamber 113 of the intake adjustment valve 11 also decreases, and the intake adjustment valve 11 opens (T14 in fig. 7), and in this state, the operation of the engine-driven compressor 1 is completely stopped.

Claims

1. A method for controlling the operation of an engine-driven compressor,

the engine-driven compressor includes an engine, a compressor body driven by the engine, and an intake air adjustment device for controlling intake air to the compressor body,

the suction adjustment device includes:

an intake regulating valve for opening and closing an intake port of the compressor main body;

a control flow path for communicating a valve-closed pressure receiving chamber of the intake adjustment valve with a discharge side of the compressor body; and

a pressure regulating valve that opens the control flow path when a discharge-side pressure of the compressor main body is equal to or higher than a predetermined rated pressure, and closes the control flow path when the discharge-side pressure of the compressor main body is lower than the rated pressure,

the engine-driven compressor is provided with:

a first bypass flow path and a second bypass flow path that bypass the pressure regulating valve and communicate the discharge side of the compressor body and a valve-closed pressure receiving chamber of the intake regulating valve, respectively;

a discharge flow path for throttling and discharging the compressed gas in the valve-closed pressure receiving chamber of the intake adjustment valve;

a first solenoid valve that opens and closes the first bypass passage; and

a second electromagnetic valve for opening and closing the second bypass flow path,

the first solenoid valve is a normally open type solenoid valve, and

the second solenoid valve is a normally closed solenoid valve having a maximum operating pressure difference higher than a maximum pressure difference that can be generated between a primary side and a secondary side of the second solenoid valve,

performing a starting operation for starting the engine in a state where the first electromagnetic valve is not energized,

when a predetermined startup operation cancellation condition is satisfied after the engine is started, the first solenoid valve is energized and the second solenoid valve is de-energized to stop the startup operation, and the engine is shifted to a normal operation in which the intake air adjustment device performs intake air control, and the engine is started

In the normal operation, when the pressure on the discharge side of the compressor body is equal to or higher than a predetermined overshoot pressure with respect to the rated pressure, the second solenoid valve is energized while the first solenoid valve is maintained in the energized state, and the overshoot-avoiding operation is shifted to the no-load operation in which the intake air adjustment valve is closed.

2. The operation control method of the engine driven compressor according to claim 1,

in the overshoot-avoiding operation, when the pressure on the discharge side of the compressor body is lower than the overshoot pressure by a predetermined low pressure and is equal to or lower than a recovery pressure higher than the rated pressure, the second solenoid valve is de-energized to end the overshoot-avoiding operation, and the normal operation is resumed.

3. The operation control method of the engine driven compressor according to claim 1 or 2,

in the start operation, the second electromagnetic valve is energized.

4. The operation control method of the engine driven compressor according to claim 1 or 2,

the engine-driven compressor is provided with a purge switch, and starts a purge operation in which the first solenoid valve is not energized and the second solenoid valve is energized by conduction of the purge switch, and ends the purge operation in which the first solenoid valve is energized and the second solenoid valve is not energized by disconnection of the purge switch, and returns to the normal operation.

5. The operation control method of the engine driven compressor according to claim 1 or 2,

when a predetermined termination condition is satisfied, the second solenoid valve is de-energized, and the engine is stopped to terminate the cooling operation.

6. An engine-driven compressor characterized in that,

comprises an engine, a compressor body driven by the engine, and an air suction adjusting device for controlling air suction of the compressor body,

the suction adjustment device includes:

the engine-driven compressor is provided with:

a first solenoid valve that opens and closes the first bypass passage;

a second electromagnetic valve that opens and closes the second bypass flow path; and

a controller that controls energization to the first solenoid valve and the second solenoid valve to switch an operation state,

the first solenoid valve is a normally open type solenoid valve, and

the controller is configured to:

7. The engine-driven compressor according to claim 6, characterized in that,

in the overshoot-avoiding operation, when the pressure on the discharge side of the compressor body is lower than the overshoot pressure by a predetermined low pressure and is equal to or lower than a recovery pressure higher than the rated pressure, the controller turns off the second solenoid valve to end the overshoot-avoiding operation, and returns to the normal operation.

8. The engine-driven compressor according to claim 6 or 7, characterized in that,

the controller energizes the second electromagnetic valve in the startup operation.

9. The engine-driven compressor according to claim 6 or 7, characterized in that,

the engine-driven compressor includes a purge switch,

the controller starts a purge operation in which the first solenoid valve is not energized and the second solenoid valve is energized by turning on the purge switch, ends the purge operation in which the first solenoid valve is energized and the second solenoid valve is not energized by turning off the purge switch, and returns to the normal operation.

10. The engine-driven compressor according to claim 6 or 7, characterized in that,

the controller performs a cooling operation in which the first solenoid valve is not energized and the second solenoid valve is energized to continue the operation of the engine by turning off a main switch, and when a predetermined termination condition is satisfied, the controller stops the engine to terminate the cooling operation while the second solenoid valve is not energized.