Method of controlling operation of engine-driven compressor, and engine-driven compressor

Abstract

To provide a method of controlling the operation of an engine- driven compressor that can smoothly transition from an unloaded operation to a full-loaded operation.SOLUTION: In transition from an unloaded operation (T1-T2 or T4-T5) to a full-loaded operation (T3-T4 or T7 and onwards), a transition operation (T2-T3 or T6-T7) is executed. In the transition operation, with an absorbing air adjustment valve 41 in a closed state, an increase in a rotation speed of an engine 50 is started from an unloaded rotation speed N1 to a full-loaded rotation speed N2 as a target rotation speed. The transition operation (T2-T3 or T6-T7) is performed for a predefined transition period of time (for example, two seconds), and after completion of the transition operation (T2-T3 or T6-T7), the absorbing air adjustment valve 40 is opened and transition is made to the full-loaded operation (T3-T4 or T7 and onwards).SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an operation control method for an engine-driven compressor, and an engine-driven compressor that executes the operation control method, and more specifically to an engine-driven compressor that transitions between no-load operation and full-load operation, and relates to an operation control method for an engine-driven compressor that enables a smooth transition from no-load operation to full-load operation, and an engine-driven compressor that executes the operation control method. [Background technology]

[0002] BACKGROUND ART Engine-driven compressors equipped with a diesel engine (hereinafter simply referred to as "engine") as a drive source for driving a compressor body are widely used in outdoor work such as civil engineering work sites and construction sites.

[0003] As an example of such an engine-driven compressor, Figure 4 shows a configuration example of an engine-driven compressor 100 that has an oil-cooled screw compressor as the compressor body 140, which compresses the gas to be compressed together with lubricating oil and discharges it as a gas-liquid mixed fluid.

[0004] In addition to the compressor main body 140 and engine 150 described above, this engine-driven compressor 100 is equipped with a receiver tank 160 into which compressed gas discharged from the compressor main body 140 as a gas-liquid mixed fluid with lubricating oil is introduced, and is configured so that the compressed gas after the lubricating oil has been separated and removed in this receiver tank 160 can be supplied to the consumer side to which an air working machine or the like (not shown) is connected.

[0005] The lubricating oil recovered in the receiver tank 160 is supplied to the compressor body 140 via an oil supply passage 164 equipped with an oil cooler 165 and an oil filter 166, and is configured to be recycled and reused.

[0006] Such an engine-driven compressor 100 is provided with an intake regulating valve 141 that controls the intake of the compressor main body 140 and a speed control device (not shown) that controls the rotational speed of the engine 150, so as to be able to supply compressed gas at a stable pressure to the consumption side. When the discharge side pressure of the compressor main body 140 (for example, the pressure in the receiver tank 160) falls below a predetermined rated pressure due to consumption of compressed gas on the consumption side, the intake regulating valve 141 is opened, and the engine 150 is operated in "full load operation" in which the target rotational speed is a predetermined high rotational speed, thereby generating compressed gas. On the other hand, when the consumption of compressed gas on the consumption side stops, for example, and the pressure in the receiver tank 160 rises above the no-load operation starting pressure, which is a predetermined high pressure relative to the above-mentioned rated pressure, the intake regulating valve 141 is closed, and the engine 150 is switched to "no-load operation" in which the engine 150 is operated in "no-load operation" in which the target rotational speed is a no-load rotational speed, which is a predetermined lower rotational speed relative to the full-load rotational speed, thereby stopping the generation of compressed gas.

[0007] As an example of an intake control device 120 that controls the opening and closing of the intake regulating valve 141 according to the pressure in the receiver tank 160, the engine-driven compressor 100 shown in Figure 4 is provided with a control flow path 121 that connects the receiver tank 160 and the closed-valve pressure chamber 142 of the intake regulating valve 141, and this control flow path 121 is provided with a pressure regulating valve 122 that closes when the pressure in the receiver tank 160 is below a predetermined rated pressure, begins opening when the pressure is above the rated pressure, and is fully open when the pressure is above the no-load operation start pressure.By controlling the introduction of operating pressure to the closed-valve pressure chamber 142 of the intake regulating valve 141 using this control flow path 121, the intake regulating valve 141 is fully open when the pressure in the receiver tank 160 is below the rated pressure, and is fully closed when the pressure is above the full-load operation start pressure, which is a predetermined higher pressure than the rated pressure.

[0008] In the engine-driven compressor 100 configured as described above, the engine 150, which is the drive source for the compressor body 140, has a small torque in the low rotation range and will stall if a large load is applied at start-up.

[0009] On the other hand, in the engine-driven compressor 100, the compressor body 140 is usually directly connected to the engine 150, and the engine 150 is configured to rotate the compressor body 140 from the time of startup.Furthermore, when the engine 150 starts, the pressure inside the receiver tank 160 is less than the rated pressure (for example, atmospheric pressure).In the configuration of the engine-driven compressor 100 equipped with the intake control device 120 configured as described above, when the engine starts, the engine 150 rotates the compressor body 140 with the intake adjustment valve 141 fully open, which places a heavy load on the engine and makes it prone to stalling.

[0010] Therefore, in order to reduce the load received from the compressor body 140 when the engine 150 is started, an engine-driven compressor 100 equipped with a start-up load reduction device indicated by reference numeral 126 in FIG. 4 has also been proposed.

[0011] This starting load reduction device 126 is composed of a bypass flow path 123 that bypasses the pressure regulating valve 122 provided in the control flow path 121 and connects the receiver tank 160 to the closed valve pressure chamber 142 of the intake control valve 141, and a starting unloader valve 124 that opens and closes this bypass flow path 123.

[0012] By providing such a starting load reduction device 126, when the engine 150 is started in a "starting load reduction mode" in which the starting unloader valve 124 is opened and the closed valve pressure receiving chamber 142 of the intake adjustment valve 141 is connected to the receiver tank 160 via the bypass flow path 123, the starting operation of the engine 150 causes the compressor body 140 to start rotating, increasing the pressure in the receiver tank 160, and this acts as the operating pressure to close the intake adjustment valve 141, thereby reducing the load on the engine 150 at the start of startup.

[0013] After the engine 150 starts, the start unloader valve 124 is closed to end operation in the start load reduction mode, and normal operation begins, with the intake control device 120 controlling the opening and closing of the intake adjustment valve 141.As a result, the intake adjustment valve 141 is controlled to open fully when the pressure in the receiver tank 160 is below the rated pressure, and to close fully at the no-load operation start pressure.

[0014] In addition, in an engine-driven compressor 100 equipped with such a starting load reduction device 126, in order to further accelerate the closing operation of the intake control valve 141 when the engine 150 is started, the engine-driven compressor of Patent Document 1 listed below has proposed an engine-driven compressor in which an airtight chamber is provided in the intake control valve, and this airtight chamber is divided by a pressure receiving body that controls the operation of the valve body, making one side a closed-valve pressure receiving chamber and the other an auxiliary pressure receiving chamber, and by starting the engine with the auxiliary pressure receiving chamber connected to the secondary side of the intake control valve, the introduction of pressure from within the receiver tank into the closed-valve pressure receiving chamber and the suction of negative pressure within the auxiliary pressure receiving chamber create a synergistic effect, allowing the intake control valve to close earlier after the engine begins its starting operation (see claim 1 and figure 1 of Patent Document 1).

[0015] Furthermore, after starting the engine in the starting load reduction mode using the starting load reduction device described above, if the compressor body is not sufficiently warmed up and the lubricating oil is highly viscous even after transitioning to normal operation, the engine may be placed under a heavy load and may stall if the transition is made to full load operation.

[0016] In this way, in order to prevent the engine from stalling when transitioning to full load operation without the compressor body being sufficiently warmed up, Patent Document 2 listed below proposes making the engine's no-load rotation speed variable, and setting the no-load rotation speed to be applied when the discharge gas temperature of the compressor body is above a predetermined temperature (for example, 60°C) and the no-load rotation speed to be applied when the temperature is below the predetermined temperature to a predetermined higher rotation speed (see claim 1 and Figure 3 of Patent Document 2). [Prior art documents] [Patent documents]

[0017] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-115598 [Patent Document 2] Japanese Patent Application Laid-Open No. 2018-127960 Summary of the Invention [Problem to be solved by the invention]

[0018] Of the engine-driven compressors described above, the configuration of the engine-driven compressor described in Patent Document 1 mentioned above allows the intake control valve to be closed early when the engine is started, thereby reducing the load on the engine immediately after starting, when it is prone to stalling.

[0019] However, in the configuration of the engine-driven compressor in Patent Document 1, even after transitioning from operation in the reduced starting load mode to normal operation, if the compressor body is still not sufficiently warmed up and the lubricating oil in the compressor body is still highly viscous, there is a risk of the engine stalling if the intake control valve is opened to transition from no-load operation to full-load operation.

[0020] On the other hand, in a configuration such as the engine-driven compressor of Patent Document 2, where the no-load rotation speed is variable and the no-load rotation speed applied when the compressor body has finished warming up (for example, when the discharge air temperature of the compressor body is 60°C or higher) is set to a predetermined high no-load rotation speed, and the rotation speed applied when the compressor body has not finished warming up (for example, when the discharge gas temperature of the compressor body is less than 60°C) is set to a predetermined high no-load rotation speed, engine stall can be prevented even when the compressor body has not finished warming up and the lubricating oil is highly viscous and the engine is switched to full-load operation.

[0021] However, in the control method described in Patent Document 2, a predetermined high no-load rotation speed is applied during no-load operation until the compressor body has completely warmed up, which increases fuel consumption during no-load operation.

[0022] Therefore, even if the compressor body is not sufficiently warmed up, it is desirable to be able to smoothly transition to full load operation without increasing the no-load rotation speed.

[0023] Furthermore, since the fuel consumption during no-load operation is fuel consumption that does not contribute to the generation of compressed gas, it is desirable to keep the engine speed during no-load operation as low as possible to keep fuel consumption low.

[0024] Here, the minimum no-load rotational speed is the rotational speed that generates the torque required to rotate the compressor body when the intake control valve is closed (no-load state). However, if the no-load rotational speed is set to this minimum rotational speed, the engine will stall because it will not be able to cope with the increase in load that occurs when switching from no-load operation to full-load operation.

[0025] Therefore, in existing engine-driven compressors, it is common to set the no-load rotational speed to a rotational speed that can generate a torque that is a certain margin above the torque that can handle the increase in load that occurs when transitioning from no-load operation to full-load operation, and there is still room for existing engine-driven compressors to lower the no-load rotational speed, and therefore room for reducing fuel consumption during no-load operation.

[0026] Therefore, the present invention has been made to eliminate the drawbacks of the above-mentioned conventional technology, and aims to provide an operation control method for an engine-driven compressor that can prevent engine stalling that may occur when transitioning from no-load operation to full-load operation, and can smoothly transition to full-load operation without increasing fuel consumption during no-load operation, preferably while reducing fuel consumption during no-load operation, and an engine-driven compressor that executes the operation control method. [Means for solving the problem]

[0027] The means for solving the problems are described below together with the reference numerals used in the description of the embodiment of the invention. These reference numerals are intended to clarify the correspondence between the claims and the description of the embodiment of the invention, and needless to say, are not used to restrict the interpretation of the technical scope of the present invention.

[0028] In order to achieve the above object, the operation control method of the engine-driven compressor 1 of the present invention includes: An operation control method for an engine-driven compressor (1) comprising an engine (50), a compressor body (40) driven by the engine (50), and an intake regulating valve (41) that controls intake to the compressor body (40) by opening and closing an intake port of the compressor body (40), and transitioning between full-load operation in which the intake regulating valve (41) is fully opened and the engine (50) is operated at a predetermined full-load rotation speed (N2) as a target rotation speed, and no-load operation in which the intake regulating valve (41) is fully closed and the engine (50) is operated at a no-load rotation speed (N1) that is a predetermined lower rotation speed than the full-load rotation speed (N2), When transitioning from the no-load operation (T1-T2 or T4-T5 in FIG. 3) to the full-load operation (T3-T4 or T7 or later in FIG. 3), a transition operation (T2-T3 or T6-T7 in FIG. 3) is performed in which the intake control valve 41 is closed and the rotation speed of the engine 50 starts to increase from the no-load rotation speed N1 to the full-load rotation speed N2 as a target rotation speed, This transition operation (T2-T3 or T6-T7 in FIG. 3) is performed until a predetermined transition time (for example, 2 seconds) has elapsed, or until the rotation speed of the engine 50 increases to a transition rotation speed, which is a predetermined higher rotation speed than the no-load rotation speed N1. After the transition operation (T2-T3 or T6-T7 in Figure 3) is completed, the intake control valve 41 is opened to transition to the full load operation (T3-T4 or T7 and thereafter in Figure 3) (see claim 1 and Figure 3).

[0029] In the above-described operation control method, after the engine 50 is started, the intake control valve 41 is fully closed until a predetermined end condition is satisfied, and the warm-up operation (T1-T2 in FIG. 3) is performed as the no-load operation in which the target rotation speed of the engine 50 is set to the no-load rotation speed N1, and After the warm-up operation is terminated by satisfying the termination condition, the operation may be switched to full load operation when the discharge side pressure of the compressor main body 40 (for example, the pressure in the receiver tank 60) becomes less than a predetermined rated pressure P2, and normal operation (after T3 in Figure 3) may be started, in which the operation is switched to no-load operation when the discharge side pressure becomes equal to or greater than a no-load operation starting pressure P3, which is a predetermined higher pressure than the rated pressure P2 (see claim 2 and Figure 3).

[0030] In this way, in a configuration in which a warm-up operation is performed, the transition operation (T2-T3 in FIG. 3) may be performed when transitioning from the no-load operation (T1-T2 in FIG. 3) during the warm-up operation to the full-load operation (T3-T4 in FIG. 3) that is performed with the start of the normal operation (see claim 3 and FIG. 3), and / or The transition operation (T6-T7 in Figure 3) may be performed when transitioning from the no-load operation (T4-T5 in Figure 3) to the full-load operation (T7 in Figure 3) during the normal operation (T3 onwards in Figure 3) after the warm-up operation (T1-T2 in Figure 3) is completed (see claim 4 and Figure 3).

[0031] The intake control valve 41 is configured to control the opening and closing operation thereof. a main control flow path 21 communicating between the closing valve pressure chamber 42 of the intake control valve 41 and the discharge side of the compressor body 40 (for example, a receiver tank 60); a pressure regulating valve 22 that closes the main control flow path 21 when the pressure on the discharge side (for example, in the receiver tank 60) of the compressor body 40 is less than the rated pressure P2, starts to open the main control flow path 21 when the pressure is equal to or greater than the rated pressure P2, and fully opens the main control flow path 21 when the pressure is equal to or greater than a no-load operation start pressure P3, which is a predetermined pressure higher than the rated pressure P2; an auxiliary control flow path 23 that bypasses the pressure regulating valve 22 and communicates between the discharge side of the compressor body 40 (for example, a receiver tank 60) and the closed valve pressure receiving chamber 42 of the intake regulating valve 41; An on-off valve 24 is provided to open and close the auxiliary control flow path 23, By opening the on-off valve 24 of the auxiliary control flow path 23, the intake adjustment valve 41 is closed during the warm-up operation (T1-T2 in FIG. 3), and by closing the on-off valve 24 of the auxiliary control flow path 23, the normal operation (T3 and thereafter in FIG. 3) can be performed by the main control flow path 21, After the warm-up operation (T1-T2 in FIG. 3) is completed, the on-off valve 24 of the auxiliary control flow path 23 is kept open until the transition operation (T2-T3 in FIG. 3) is completed. During the transition operation (T2-T3 in FIG. 3), the intake adjustment valve 41 is kept in a closed state. When the transition operation (T2-T3 in Figure 3) is completed, the on-off valve 24 of the auxiliary control flow path 23 may be closed to start the normal operation (T3 and thereafter in Figure 3) (see claim 5, Figures 1 and 3).

[0032] In this case, during the normal operation (after T3 in FIG. 3) performed with the on-off valve 24 of the auxiliary control flow path 23 closed, when the pressure on the discharge side of the compressor body 40 (for example, in the receiver tank 60) drops from a pressure equal to or higher than the no-load operation start pressure P3 to a predetermined transition operation start pressure P4, which is a pressure lower than the no-load operation start pressure P3 (T6 in FIG. 3), the on-off valve 24 of the auxiliary control flow path 23 is opened and the intake adjustment valve 41 is closed, and the transition operation (T6-T7 in FIG. 3) is started, When the transition operation (T6-T7 in Figure 3) is completed, the on-off valve 24 of the auxiliary control flow path 23 may be closed to transition to the full load operation (T7 and thereafter in Figure 3) (see claim 6, Figures 1 and 3).

[0033] Furthermore, the engine-driven compressor 1 of the present invention is An engine-driven compressor 1 is provided with an engine 50, a compressor body 40 driven by the engine 50, and an intake regulating valve 41 that opens and closes an intake port of the compressor body 40 to control intake to the compressor body 40, and is equipped with an operation control means 10 that transitions between a full-load operation in which the intake regulating valve 41 is fully opened and the engine 50 is operated at a predetermined full-load rotation speed N2 as a target rotation speed, and a no-load operation in which the intake regulating valve 41 is fully closed and the engine 50 is operated at a no-load rotation speed N1 that is a predetermined lower rotation speed than the full-load rotation speed N2 as a target rotation speed, The operation control means 10 When transitioning from the no-load operation (T1-T2 or T4-T5 in FIG. 3) to the full-load operation (T3-T4 or T7 or later in FIG. 3), a transition operation (T2-T3 or T6-T7 in FIG. 3) is performed in which the intake control valve 41 is closed and the rotation speed of the engine 50 starts to increase from the no-load rotation speed N1 to the full-load rotation speed N2 as a target rotation speed, The transition operation (T2-T3 or T6-T7 in FIG. 3) is performed until a predetermined transition time (for example, 2 seconds) has elapsed or until the rotation speed of the engine 50 increases to a transition rotation speed that is a predetermined higher rotation speed than the no-load rotation speed N1, After the transition operation (T2-T3 or T6-T7 in Figure 3) is completed, the intake control valve 41 is opened to transition to the full load operation (T3-T4 or T7 and thereafter in Figure 3) (see claim 7 and Figures 1-3).

[0034] In the engine-driven compressor 1 having the above configuration, The operation control means 10 is provided with an operation state determination means 71, After the engine 50 is started, the intake control valve 41 is fully closed until the operating state determination means 71 determines that a predetermined termination condition is satisfied, and the warm-up operation (T1-T2 in FIG. 3) is performed, which is the no-load operation in which the target rotation speed of the engine 50 is set to the no-load rotation speed N1, and When the operating state determination means 71 determines that the termination condition is satisfied, it terminates the warm-up operation, and then performs the full-load operation when the discharge side pressure of the compressor main body 40 (for example, the pressure in the receiver tank 60) is less than a predetermined rated pressure P2, and performs the no-load operation when the discharge side pressure is equal to or greater than a no-load operation starting pressure P3, which is a predetermined higher pressure than the rated pressure P2, thereby starting normal operation (after T3 in Figure 3) (see claim 8 and Figures 1-3).

[0035] In this way, in the configuration in which the warm-up operation (T1-T2) is performed, the operation control means 10 may be configured to execute the transition operation (T2-T3 in FIG. 3) when transitioning from the no-load operation (T1-T2 in FIG. 3) in the warm-up operation to the full-load operation (T3-T4 in FIG. 3) that is performed with the start of the normal operation (see claim 9, FIGS. 1-3), and / or The operation control means 10 may also be configured to execute the transition operation (T6-T7 in Figure 3) when transitioning from the no-load operation (T4-T5 in Figure 3) performed during the normal operation (T3 onwards in Figure 3) to the full-load operation (T7 onwards in Figure 3) (Claim 10, Figures 1-3).

[0036] The operation control means 10 further includes an intake control device 20 for controlling the opening and closing operation of the intake adjustment valve 41, The intake control device 20, a main control flow path 21 communicating between the closing valve pressure chamber 42 of the intake control valve 41 and the discharge side of the compressor body 40 (for example, a receiver tank 60); a pressure regulating valve 22 that closes the main control flow path 21 when the pressure on the discharge side (for example, the receiver tank 60) of the compressor body 40 is less than the rated pressure P2, starts to open the main control flow path 21 when the pressure is equal to or greater than the rated pressure P2, and fully opens the main control flow path 21 when the pressure is equal to or greater than a no-load operation start pressure P3, which is a predetermined pressure higher than the rated pressure P2; an auxiliary control flow path 23 that bypasses the pressure regulating valve 22 and communicates between the discharge side of the compressor body 40 (for example, a receiver tank 60) and the closed valve pressure receiving chamber 42 of the intake regulating valve 41; a solenoid valve 24 for opening and closing the auxiliary control flow path 23; A controller 70 for controlling the operation of the solenoid valve is provided, By opening the solenoid valve 24 of the auxiliary control flow path 23, the intake control valve 41 is closed during the warm-up operation (T1-T2 in FIG. 3), and by closing the solenoid valve 24 of the auxiliary control flow path 23, the normal operation (T3 and thereafter in FIG. 3) can be performed by the main control flow path 21. After the warm-up operation (T1-T2 in FIG. 3) is completed, the solenoid valve 24 of the auxiliary control flow path 23 is kept open until the transition operation (T2-T3 in FIG. 3) is completed. During the transition operation (T2-T3 in FIG. 3), the intake adjustment valve 41 is kept in a closed state. When the transition operation (T2-T3 in Figure 3) is completed, the solenoid valve 24 of the auxiliary control flow path 23 may be closed to start the normal operation (T3 and thereafter in Figure 3) (see claim 11, Figures 1 and 3).

[0037] In this case, pressure detection means 81 and 82 are provided to detect the discharge side pressure of the compressor body 40, The intake control device 20, During the normal operation (after T3 in FIG. 3) performed with the auxiliary control flow path 23 closed, when the pressure on the discharge side of the compressor body (for example, in the receiver tank 60) detected by the pressure detection means 81, 82 drops from a pressure equal to or higher than the no-load operation start pressure P3 to a predetermined transition operation start pressure P4 which is a pressure lower than the no-load operation start pressure P3, the electromagnetic valve 24 of the auxiliary control flow path 23 is opened and the intake adjustment valve 41 is closed to start the transition operation (T6-T7 in FIG. 3), When the transition operation (T6-T7 in FIG. 3) is completed, the solenoid valve 24 of the auxiliary control flow path 23 may be configured to be closed (see claim 12 and FIGS. 1 and 3).

[0038] The intake control device 20 provided in the operation control means 10 is a control flow path 21' communicating between the closing valve pressure chamber 42 of the intake control valve 41 and the discharge side of the compressor body 40 (for example, a receiver tank 60); a variable valve 25 such as an electro-pneumatic proportional valve that changes the flow area of ​​the control flow path 21' between fully open and fully closed; Pressure detection means 81, 82 for detecting the discharge side pressure of the compressor body 40, and A configuration including a controller 70 that controls the operation of the variable valve 25 based on the detection signals of the pressure detection means 81, 82 may be adopted (see claim 13 and FIG. 2). [Effects of the Invention]

[0039] With the configuration of the present invention described above, the engine-driven compressor 1 that executes the operation control method of the present invention can achieve the following significant effects.

[0040] When transitioning from no-load operation (see T1-T2 or T4-T5 in Figure 3) to full-load operation (T3-T4 or T7 and thereafter in Figure 3), a transition operation (T2-T3 or T6-T7 in Figure 3) is performed in which the intake control valve 41 is closed and the rotation speed of the engine 50 begins to increase from the no-load rotation speed N1 to the full-load rotation speed N2 as the target rotation speed, and this transition operation is performed until a predetermined transition time has elapsed or until the rotation speed of the engine 50 has increased to a predetermined transition rotation speed, after which the intake control valve 41 is opened to transition to full-load operation.As a result, an increase in load occurs as the intake control valve 41 opens in a state in which the rotation speed of the engine 50 is increased above the no-load rotation speed N1, and therefore the torque is increased, and therefore it is possible to prevent the engine 50 from stalling even when transitioning to full-load operation is made when, for example, the compressor body 40 has not been sufficiently warmed up and the lubricating oil is highly viscous.

[0041] Furthermore, the operation control method of the present invention is capable of dealing with the increase in load that accompanies the transition to full load operation without increasing the no-load rotation speed N1, thereby making it possible to reduce fuel consumption during no-load operation compared to the control method described in Patent Document 2 cited above, which prevents engine stall by applying a predetermined high no-load rotation speed until the compressor body has completely warmed up.

[0042] After the engine 50 is started, warm-up operation (see T1-T2 in Figure 3) is performed in a state where the intake control valve 41 is closed and the target rotation speed of the engine 50 is set to the no-load rotation speed N1 until a predetermined termination condition is met, and after the warm-up operation is completed, normal operation (from T3 in Figure 3 onwards) is started in which the operating state is switched between no-load operation and full-load operation depending on changes in the discharge side pressure of the compressor main body 40 (for example, the pressure in the receiver tank 60).In this configuration, since the engine 50 and / or compressor main body 40 are warmed up by the warm-up operation, it is possible to make it less likely that the engine will stall when transitioning to full-load operation, especially when transitioning to full-load operation, which is the first operation after the engine-driven compressor 1 is started.

[0043] In the case of an engine-driven compressor 1 configured to perform the warm-up operation described above, by performing the transition operation (T2-T3 in Figure 3) described above when transitioning from no-load operation performed during warm-up operation (T1-T2 in Figure 3) to full-load operation (T3-T4 in Figure 3) performed with the start of normal operation (T3 onwards in Figure 3), it is possible to effectively prevent stalling of the engine 50 when transitioning to the first full-load operation after start-up, when the temperature of the compressor body 40 is relatively low.

[0044] Furthermore, by applying the above-mentioned transition operation not only when the engine-driven compressor 1 transitions to its first full-load operation (T3-T4 in Figure 3) after startup, but also when transitioning from no-load operation (T4-T5 in Figure 3) to full-load operation (T7 and thereafter in Figure 3) during normal operation (when transitioning to full-load operation for the second or subsequent times after startup), it is possible to prevent the engine 50 from stalling when transitioning to full-load operation even when the compressor body 40 is at a relatively low temperature even after normal operation has begun.

[0045] In particular, if the system is configured to always perform transition operation when transitioning to full-load operation, the rotational speed of the engine 50 increases when full-load operation is initiated by transition operation, so even if the no-load rotational speed N1 is set to a relatively low rotational speed that has a slight margin above the minimum rotational speed required to generate the torque required to rotate the compressor body in an unloaded state, stalling of the engine 50 can be prevented, and therefore fuel consumption during no-load operation can be reduced.

[0046] In a configuration in which the intake control device 20 that opens and closes the intake regulating valve 41 is provided with a main control flow path 21 that connects the closed valve pressure chamber 42 of the intake regulating valve 41 to the discharge side of the compressor main body 40 (for example, the receiver tank 60), a pressure regulating valve 22 that opens and closes the main control flow path 21, an auxiliary control flow path 23 that bypasses the pressure regulating valve 22 and connects the discharge side (receiver tank 60) of the compressor main body 40 to the closed valve pressure chamber 42 of the intake regulating valve 41, and an opening and closing valve 24 that opens and closes the auxiliary control flow path 23, warm-up operation can be easily performed by starting the engine 50 with the opening and closing valve (solenoid valve) 24 of the auxiliary control flow path 23 open, and by closing the opening and closing valve (solenoid valve) 24 provided in the auxiliary control flow path 23, warm-up operation can be terminated with relatively simple control and normal operation can be started.

[0047] Furthermore, by opening the opening / closing valve (solenoid valve) 24 of the auxiliary control flow path 23 even during normal operation, the intake adjustment valve 41 can be closed even if the pressure in the receiver tank 60 is below the rated pressure P2, making it easy to close the intake adjustment valve 41 during transition operation performed during normal operation.

[0048] Furthermore, if the intake control device 20 is configured with a control flow path 21' that connects the closed valve pressure chamber 42 of the intake adjustment valve 41 and the discharge side of the compressor main body 40 (for example, the receiver tank 60), a variable valve 25 such as an electro-pneumatic proportional valve that changes the flow path area of ​​the control flow path 21' between fully open and fully closed, pressure detection means 81, 82 that detect the discharge side pressure of the compressor main body 40, and a controller 70 that controls the operation of the variable valve 25, the configuration of the intake control device 20 can be simplified. [Brief explanation of the drawings]

[0049] [Figure 1] FIG. 1 is an explanatory diagram of an engine-driven compressor according to the present invention. [Figure 2] FIG. 10 is an explanatory diagram showing a modified example of the engine-driven compressor of the present invention. [Figure 3] 2 is a time chart showing the operation of each part of the engine-driven compressor shown in FIG. 1. [Figure 4] FIG. 1 is an explanatory diagram of a conventional engine-driven compressor. DETAILED DESCRIPTION OF THE INVENTION

[0050] An example of the configuration of an engine-driven compressor 1 that executes the operation control method of the present invention will be described below with reference to the accompanying drawings.

[0051] [Overall structure of engine-driven compressor] The reference numeral 1 in Figure 1 denotes an engine-driven compressor of the present invention, and this engine-driven compressor 1 comprises a compressor main body 40, an engine 50 that drives the compressor main body 40, and an intake adjustment valve 41 that opens and closes the intake port of the compressor main body 40 to control the intake of air to the compressor main body 40.

[0052] In the configuration of this embodiment, which employs an oil-cooled screw compressor as the compressor main body 40, which compresses the gas to be compressed together with lubricating oil for lubrication, cooling, and sealing, a receiver tank 60 is provided for storing the compressed gas discharged from the compressor main body 40 as a gas-liquid mixed fluid with lubricating oil, and the compressed gas discharged from the compressor main body 40 is introduced into the receiver tank 60 to separate and remove the lubricating oil, after which it can be supplied via a pressure regulating valve 61 and a service valve 62 to the consumer side, which consists of an air working machine or the like (not shown) connected to the service valve 62.

[0053] On the other hand, the lubricating oil separated from the compressed gas and recovered in the receiver tank 60 is supplied to the compressor body 40 via an oil supply passage 64 equipped with an oil cooler 65 and an oil filter 66, thereby enabling the lubricating oil to be circulated and reused.

[0054] [Operation control means] (1) Overall configuration of operation control means The engine-driven compressor 1 configured as described above is provided with an operation control means 10 that transitions the operating state between full-load operation, in which the intake regulating valve 41 is fully opened and the engine 50 is operated at a predetermined full-load rotation speed N2 as a target rotation speed, and no-load operation, in which the intake regulating valve 41 is fully closed and the engine 50 is operated at a no-load rotation speed N1, which is a predetermined lower rotation speed than the full-load rotation speed N2, as a target rotation speed.

[0055] This operation control means 10 is equipped with an intake control device 20 that controls the intake of the compressor main body 40 by controlling the opening and closing operation of an intake adjustment valve 41 that opens and closes the intake port of the compressor main body 40, in order to enable the transition of the operating state between the full load operation and no load operation described above, and a speed control device 30 that changes the rotational speed of the engine 50 between a full load rotational speed N2 and a no load rotational speed N1.

[0056] (2) Intake control device In the engine-driven compressor 1 shown in Figure 1, the intake control device 20, which controls the operation of the intake adjustment valve 41 provided at the intake port of the compressor main body 40, is composed of a main control flow path 21 that connects the closed valve pressure chamber 42 of the intake adjustment valve 41 to the discharge side of the compressor main body 40 (receiver tank 60 in the illustrated configuration), a pressure adjustment valve 22 that opens and closes the main control flow path 21, an auxiliary control flow path 23 that bypasses the pressure adjustment valve 22 and connects the discharge side of the compressor main body 40 (receiver tank 60 in the illustrated example) to the closed valve pressure chamber 42 of the intake adjustment valve 41, an opening / closing valve 24 consisting of an electromagnetic valve that opens and closes the auxiliary control flow path 23, and a controller 70 that controls the operation of the opening / closing valve (electromagnetic valve) 24.

[0057] The pressure regulating valve 22 provided in the aforementioned main control flow path 21 is configured to close when the discharge side pressure of the compressor main body 40 (in this embodiment, the pressure in the receiver tank 60) is below a predetermined rated pressure P2, to begin to open when it is above the rated pressure P2, and to fully open when it is above the no-load operation start pressure P3, which is a predetermined higher pressure than the rated pressure P2.As a result, in the normal operation state where the solenoid valve 24 is closed and the auxiliary control flow path 23 is closed, when the pressure in the receiver tank 60 is below the rated pressure P2, no operating pressure is introduced into the closing valve pressure receiving chamber 42 of the intake control valve 41, and the intake control valve 41 is fully open.When the pressure in the receiver tank 60 rises to above the rated pressure P2, the introduction of operating pressure into the closing valve pressure receiving chamber 42 of the intake control valve 41 begins, and the intake control valve 41 begins to close.

[0058] On the other hand, when the solenoid valve 24 provided in the aforementioned auxiliary control flow path 23 is opened, the pressure regulating valve 22 provided in the main control flow path 21 is bypassed and communication is established between the receiver tank 60 and the closed valve pressure chamber 42 of the intake regulating valve 41 via the auxiliary control flow path 23, so that the intake regulating valve 41 can be closed even if the pressure in the receiver tank 60 is below the rated pressure P2 while the compressor main body 40 is operating.

[0059] The aforementioned controller 70 is composed of an electronic control device such as a microcontroller, and by executing a pre-stored program, an intake adjustment section 72 is realized which controls the opening and closing operation of the solenoid valve 24 provided in the auxiliary control flow path 23 based on the operating state of the engine 50 received from an engine control unit (ECU) 51 provided in the engine 50 and detection signals from various sensors 81 to 83.

[0060] In addition, the controller 70, by executing a pre-stored program, realizes an operating state determination means 71 that determines whether or not a pre-set termination condition (in this embodiment, a pre-set warm-up time has elapsed since the engine 50 was started) has been met, such as the passage of a pre-set time since the engine 50 was started, the rise of the engine 50's cooling water and lubricating oil to a pre-set temperature, or the rise of the compressor body's discharge air and lubricating oil to a pre-set temperature, based on information received from the ECU 51 and various sensors 81 to 83.

[0061] The intake adjustment unit 72 of the controller 70 maintains the solenoid valve 24 provided in the auxiliary control flow path 23 in an open state from the start of the engine 50 until the operating state determination means 71 determines that the conditions for ending the warm-up operation have been met, i.e., during the warm-up operation.

[0062] In addition, the intake adjustment unit 72 of the controller 70 maintains the solenoid valve 24 provided in the auxiliary control flow path 23 in an open state until a predetermined transition period (for example, 2 seconds) has elapsed after the operating state determination means 71 determines that the conditions for terminating the warm-up operation have been met and the warm-up operation has ended.

[0063] In this embodiment, the intake adjustment unit 72 of the controller 70 is configured to maintain the solenoid valve 24 in an open state after the warm-up operation is completed until a predetermined transition period (for example, 2 seconds) has elapsed, but instead of this configuration, the intake adjustment unit 72 may be configured to maintain the solenoid valve 24 in an open state until the rotational speed of the engine 50 reaches a predetermined transitional rotational speed higher than the no-load rotational speed N1 after the warm-up operation is completed.

[0064] As described above, when the operating state determination means 71 determines that the conditions for terminating the warm-up operation have been met and the transition period has elapsed (or the transition rotation speed has been reached), the intake adjustment unit 72 of the controller 70 closes the solenoid valve 24 provided in the auxiliary control flow path 23.

[0065] When the solenoid valve 24 is closed, the operating pressure is introduced into the closing valve pressure chamber 42 of the intake control valve 41 only through the main control flow path 21, and in response to the opening and closing operation of the pressure control valve 22 provided in the main control flow path 21, the intake control valve 41 is fully open when the pressure in the receiver tank 60 is below the rated pressure P2, begins to close when the pressure exceeds the rated pressure P2, and is fully closed when the pressure exceeds the no-load operation start pressure P3, which is a predetermined higher pressure than the rated pressure P2.

[0066] On the other hand, when the pressure in the receiver tank 60 drops from the no-load operation start pressure P3 to a pressure below the no-load operation start pressure P3, a predetermined transition operation start pressure P4, which is a pressure below the no-load operation start pressure P3, is set within a range that is not significantly lower than the aforementioned rated pressure P2, and when the pressure in the receiver tank 60 drops to the transition operation start pressure P4, the intake adjustment unit 72 of the controller 70 closes the intake adjustment valve 41 by keeping the solenoid valve 24 provided in the auxiliary control flow path 23 open until a predetermined transition time (for example, 2 seconds) has elapsed, and closes the solenoid valve 24 of the auxiliary control flow path 23 after the aforementioned transition time has elapsed, returning to the opening and closing control of the intake adjustment valve 41 by the main control flow path 21.

[0067] In the embodiment shown in Figure 3, the transition operation start pressure P4 is set to a pressure lower than the rated pressure P2, but the transition operation start pressure P4 may also be set to a pressure higher than the rated pressure P2 as long as it is lower than the no-load operation start pressure P3.

[0068] In addition, in the embodiment shown in Figure 1, the intake control device 20 is configured to have two control flow paths: a main control flow path 21 and an auxiliary control flow path 23, and the opening and closing operation of the intake adjustment valve 41 described above is performed by the operation of the pressure adjustment valve 22 provided in the main control flow path 21 and the opening and closing control of the solenoid valve 24 provided in the auxiliary control flow path 23.

[0069] However, the configuration of the intake control device 20 is not limited to the configuration shown in Figure 1, and for example, as shown in Figure 2, a control flow path 21' may be provided that connects the closed valve pressure chamber 42 of the intake adjustment valve 41 and the receiver tank 60, and a variable valve 25 such as an electro-pneumatic proportional valve that changes the flow path area of ​​this control flow path 21' between fully open and fully closed may be provided.In this configuration, by controlling the operation of the electro-pneumatic proportional valve 25 with the intake adjustment section 72 of the controller 70, it is possible to realize the functions of both the pressure adjustment valve 22 and the solenoid valve 24 shown in Figure 1 using a single electro-pneumatic proportional valve 25.

[0070] (3) Speed ​​control device In the illustrated embodiment, the speed control device 30 that controls the rotational speed of the engine 50 is composed of an engine control unit (ECU) 51 provided in the engine 50, a controller 70 that receives operation information of the engine 50 from the ECU 51 and outputs a target rotational speed of the engine 50 to the ECU 51, and pressure detection means 81 and / or 82 such as a pressure sensor that detects the pressure on the discharge side of the compressor main body 40 (in the illustrated example, the pressure in the receiver tank 60 and the pressure on the secondary side of the pressure regulating valve 22) and outputs it to the controller 70.

[0071] In the illustrated embodiment, a speed control unit 73 that controls the rotational speed of the engine 50 is realized by a controller 70 that is common to the controller 70 that constitutes the intake control device 20 described above, but the controller that constitutes the speed control device 30 and the controller that constitutes the intake control device 20 may also be provided independently.

[0072] The speed control section 73 of the controller 70 outputs the no-load rotation speed N1 to the ECU 51 as the target rotation speed until the operating state determination means 71 determines that the warm-up operation termination condition has been met.

[0073] Then, when the operating state determination means 71 determines that the conditions for terminating the warm-up operation have been met, the speed control unit 73 of the controller 70 terminates the rotational speed control of the engine 50, which has the no-load rotational speed N1 as the target rotational speed, and executes rotational speed control that changes the rotational speed of the engine 50 according to the discharge side pressure of the compressor main body 40, which in this embodiment is the pressure inside the receiver tank 60.

[0074] In the illustrated embodiment, the speed control unit 73 monitors pressure changes in the receiver tank 60 based on the secondary pressure of the pressure regulating valve 22 detected by the pressure detection means 82, and when the pressure in the receiver tank 60 rises, when the pressure in the receiver tank 60 is less than the rated pressure P2 (when the pressure detected by the pressure detection means 82 is 0 Pa in gauge pressure), it outputs the full load rotation speed N2 to the ECU 51 as the target rotation speed, and when the pressure in the receiver tank 60 rises to or above the no-load operation start pressure P3, which is a predetermined higher pressure than the rated pressure P2, it outputs the no-load rotation speed N1 to the ECU 51 as the target rotation speed.

[0075] Conversely, in a situation where the pressure in the receiver tank 60 drops from a state where it is equal to or higher than the no-load operation start pressure P3 to a state where it drops below the no-load operation start pressure P3, for example, due to the start of consumption of compressed gas on the consumption side, if the pressure in the receiver tank 60 detected by the pressure detection means 81 exceeds the aforementioned transition operation start pressure P4, the speed control unit 73 will maintain the engine 50 at the no-load rotational speed N1 without increasing the rotational speed, even if the pressure in the receiver tank 60 drops below the no-load operation start pressure P3 and the secondary side pressure of the pressure control valve 22 detected by the pressure detection means 82 changes, and when the pressure in the receiver tank 60 drops below the aforementioned transition operation start pressure P4, the speed control unit 73 will change the target rotational speed output to the ECU 51 from the no-load rotational speed N1 to the full-load rotational speed N2.

[0076] As a result, the rotational speed of the engine 50 increases from the no-load rotational speed N1 to the target rotational speed, which is the full-load rotational speed N2, and is maintained at the full-load rotational speed N2 until the pressure in the receiver tank 60 again rises above the no-load operation start pressure P3.

[0077] [Operation explanation, etc.] The operation of each part of the engine-driven compressor 1 of the present invention described above will be described with reference to the time chart of FIG.

[0078] When a starting operation is performed (T1), for example, by turning on a key switch (not shown) provided on the engine-driven compressor 1, the engine 50 of the engine-driven compressor 1 starts.

[0079] As the engine 50 starts, the speed control unit 73 of the controller 70 performs warm-up operation (T1-T2) by setting the target rotation speed of the engine 50 to the no-load rotation speed N1 until the operating state determination means 71 determines that the conditions for terminating the warm-up operation have been met.

[0080] Furthermore, the intake adjustment unit 72 of the controller 70 maintains the solenoid valve 24 provided in the auxiliary control flow path 23 in an open state during the warm-up operation (T1-T2) described above.

[0081] As a result, the closed valve pressure chamber 42 of the intake adjustment valve 41 is brought into communication with the receiver tank 60 via the auxiliary control flow path 23 .

[0082] Before the engine 50 starts, the pressure inside the receiver tank 60 is atmospheric pressure (0 Pa gauge pressure), and the intake control valve 41 is fully open. However, when the engine 50 starts and the compressor main body 40 directly connected to the engine 50 begins to rotate, the pressure inside the receiver tank 60 begins to rise, and when it reaches the starting unload pressure P1, the intake control valve 41 is fully closed, closing the intake port of the compressor main body 40.

[0083] As a result, with the intake regulating valve 41 closed, a warm-up operation (T1-T2) is performed under no-load operation with the rotation speed of the engine 50 set to the no-load rotation speed N1.

[0084] When the warm-up operation is completed (T2), the speed control section 73 of the controller 70 changes the target rotation speed of the engine 50 output to the ECU 51 from the no-load rotation speed N1 to the full-load rotation speed N2, and as a result, the rotation speed of the engine 50 starts to increase from the no-load rotation speed N1 to the full-load rotation speed N2.

[0085] On the other hand, the intake adjustment unit 72 of the controller 70 keeps the solenoid valve 24 provided in the auxiliary control flow path 23 in an open state even after the warm-up operation is completed (T2), until a predetermined transition period (T2-T3; for example, 2 seconds) has elapsed, thereby keeping the intake adjustment valve 41 in a closed state after the above-mentioned warm-up operation, until a predetermined transition period (T2-T3; for example, 2 seconds) has elapsed.

[0086] As a result, a transition operation is executed in which the rotation speed of the engine 50 starts to increase while the intake regulating valve 41 is maintained in a closed state (T2-T3).

[0087] When the above-mentioned transition operation is completed (T3), the intake adjustment unit 72 of the controller 70 closes the solenoid valve 24 provided in the auxiliary control flow path 23, thereby stopping the introduction of operating pressure to the closing valve pressure chamber 42 of the intake adjustment valve 41 via the auxiliary control flow path 23, and normal operation begins in which the opening and closing control of the intake adjustment valve 41 is performed by the main control flow path 21 and the pressure adjustment valve 22 provided in the main control flow path 21, and the intake adjustment valve 41 is opened and closed according to the pressure in the receiver tank 60.

[0088] At the end (T3) of the aforementioned transition operation (T2-T3), the pressure in the receiver tank 60 is at the starting unload pressure P1, which is lower than the rated pressure P2, and therefore the pressure regulating valve 22 provided in the main control flow path 21 is in a closed state.

[0089] Therefore, when the solenoid valve 24 of the auxiliary control flow path 23 is closed in this state, the introduction of operating pressure to the closed valve pressure chamber 42 of the intake control valve 41 stops, and with the end of the transition operation (T2-T3), the intake control valve 41 becomes fully open and transitions to full load operation (T3-T4).

[0090] In this way, when the warm-up operation (T1-T2) is completed and normal operation (T3 and onwards) begins, the operating state transitions from the no-load operation that was performed during the warm-up operation to full-load operation as normal operation begins, and the compressor main body 41 begins to generate compressed gas, placing a heavy load on the engine 50.

[0091] However, in the configuration of the engine-driven compressor 1 of the present invention, when transitioning from no-load operation (T1-T2) during warm-up operation to full-load operation (T3-T4) accompanying the start of normal operation, the aforementioned transition operation (T2-T3) is interposed, and during the transition operation (T2-T3) the rotational speed of the engine 50 is increased to a rotational speed higher than the no-load rotational speed N1, thereby increasing the engine torque and opening the intake control valve 41, thereby preventing the engine 50 from stalling even if the load increases due to the opening of the intake control valve 41.

[0092] Even after the transition operation (T2-T3) has elapsed, the rotation speed of the engine 50 increases toward the full load rotation speed N2, which is the target rotation speed, and when it reaches the full load rotation speed N2, it is maintained constant at the full load rotation speed N2.

[0093] When the intake control valve 41 is fully opened and the engine 50 is operated with the full load rotation speed N2 as the target rotation speed, the pressure inside the receiver tank 60 rises, and in response to this pressure rise, the speed control section 73 of the controller 70 maintains the rotation speed of the engine 50 at the full load rotation speed N2 as long as the pressure inside the receiver tank 60 remains below the rated pressure P2, even if the pressure rises.

[0094] On the other hand, when the pressure in the receiver tank 60 exceeds the rated pressure P2, the speed control unit 73 of the controller 70 gradually reduces the target rotational speed of the engine 50 from the full-load rotational speed N2 in accordance with the increase in pressure in the receiver tank 60, and when the pressure in the receiver tank 60 exceeds the no-load operation start pressure P3, the target rotational speed of the engine 50 is reduced to the no-load rotational speed N1 (T4).

[0095] In addition, under the control of the main control flow path 21 and pressure regulating valve 22 of the intake control device 20, the intake regulating valve 41 is fully open when the pressure in the receiver tank 60 is below the rated pressure P2, and when the pressure rises above the rated pressure P2, the intake regulating valve 41 begins to close, and when the pressure rises above the no-load operation start pressure P3, the intake regulating valve 41 is fully closed (T4).

[0096] As a result, the engine-driven compressor 1 transitions to no-load operation (T4-T5), and while the pressure in the receiver tank 60 is equal to or higher than the no-load operation start pressure P3, the intake control valve 41 is closed and the engine 50 is operated at the no-load rotation speed N1.

[0097] In this way, when the service valve 62 is opened during no-load operation (T4-T5) and the consumption of compressor gas by pneumatic equipment etc. connected to the consumption side begins, the pressure in the receiver tank 60 drops below the full-load operation start pressure P3.

[0098] As the pressure in the receiver tank 60 decreases, the pressure regulating valve 22 provided in the main control flow path 21 of the intake control device 20 begins to close, and the operating pressure introduced into the closing valve pressure chamber 42 of the intake regulating valve 41 is reduced, causing the intake regulating valve 41 to begin to open, and when the pressure in the receiver tank 60 drops below the rated pressure P2, the intake regulating valve 41 becomes fully open (T5-T6).

[0099] On the other hand, even if the secondary pressure of the pressure regulating valve 22 detected by the pressure detection means 82 changes due to the pressure in the receiver tank 60 dropping below the no-load operation start pressure P3, the speed control section 73 of the controller 70 constituting the speed control device 30 maintains the rotational speed of the engine 50 at the no-load rotational speed N1 until the pressure in the receiver tank 60 drops to the predetermined transition operation start pressure P4 (T5-T6).

[0100] As the consumption of compressed gas continues on the consumption side, the pressure in the receiver tank 60 further decreases and falls below the transition operation start pressure P4, and the intake adjustment unit 72 of the controller 70 opens the solenoid valve 24 provided in the auxiliary control flow path 23, which starts the introduction of operating pressure to the closing valve pressure receiving chamber 42 of the intake adjustment valve 41 via the auxiliary control flow path 23, causing the intake adjustment valve 41 to become fully closed (T6).

[0101] Furthermore, when the pressure in the receiver tank 60 drops below the transition operation start pressure P4, the speed control section 73 of the controller 70 that constitutes the speed control device 30 changes the target rotational speed of the engine 50 from the no-load rotational speed N1 to the full-load rotational speed N2, causing the rotational speed of the engine 50 to start increasing from the no-load rotational speed N1 toward the full-load rotational speed N2 (T6).

[0102] In this way, in the engine-driven compressor 1 of the present invention, even if the pressure in the receiver tank 60 falls below the no-load operation start pressure P3 and the intake control valve 41 begins to open, the no-load rotation speed N1 is maintained without increasing the rotation speed of the engine 50 until the pressure in the receiver tank 60 drops to the transition operation start pressure P4 (T5-T6), and then the rotation speed of the engine 50 is increased with the intake control valve 41 closed (T6 onwards), thereby preventing an increase in load and the resulting stall of the engine that occurs when the engine rotation speed is increased with the intake control valve 41 open.

[0103] The intake adjustment unit 72 of the controller 70 that constitutes the intake control device 20 opens the solenoid valve 24 provided in the auxiliary control flow path 23 (T6) and then closes the solenoid valve 24 provided in the auxiliary control flow path 23 and opens the intake adjustment valve 41 after a predetermined transition period (for example, 2 seconds) has elapsed (T7).

[0104] In this way, during the aforementioned transition period (T6-T7), the engine-driven compressor 1 performs transition operation in which the rotational speed of the engine 50 begins to increase with the intake control valve 41 closed, and then opens the intake control valve 41 to transition to full-load operation after increasing the rotational speed of the engine 50 to a certain extent and increasing the engine torque, thereby preventing the engine from stalling even when transitioning from no-load operation to full-load operation during normal operation.

[0105] 〔others〕 In the embodiment described above, a configuration has been described in which a transition operation is performed intermediately when transitioning from no-load operation during warm-up to full-load operation when normal operation begins (when transitioning to full-load operation for the first time after starting the engine-driven compressor 1) and when transitioning from no-load operation to full-load operation during normal operation (when transitioning to full-load operation for the second or subsequent times after starting the engine-driven compressor 1), but such a transition operation may be applied to only one of these.

[0106] Furthermore, when the above-mentioned transition operation is performed when transitioning to full load operation during normal operation (the second or subsequent transition to full load operation after starting the engine-driven compressor 1), the above-mentioned transition operation may be applied only when transitioning from the first no-load operation to full load operation during normal operation (the second transition to full load operation after starting the engine-driven compressor 1), or the above-mentioned transition operation may be applied when transitioning to full load operation until a specified condition is met, such as the discharge gas temperature or lubricating oil temperature of the compressor main body 40 rising above a specified value, or further, the above-mentioned transition operation may be performed when transitioning to full load operation every time the engine-driven compressor 1 is in operation.

[0107] If the configuration is such that the above-mentioned transition operation is always performed when transitioning to full-load operation, it is possible to smoothly transition from no-load operation to full-load operation even if the no-load rotation speed is set to the lowest possible rotation speed, and fuel consumption during no-load operation can be reduced. [Explanation of symbols]

[0108] 1. Engine-driven compressor 10 Operation control means 20 Intake control device 21 Main control channel 21' Control Channel 22 Pressure Regulating Valve 23 Auxiliary control channel 24 On-off valve (solenoid valve) 25 Variable valve (electro-pneumatic proportional valve) 30 Speed ​​control device 40 Compressor body 41 Intake adjustment valve 42 Closed valve pressure chamber 50 Engine 51 Engine Control Unit (ECU) 60 Receiver Tank 61 Pressure Regulating Valve 62 Service valve 64 Oil supply passage 65 Oil cooler 66 Oil filter 70 Controller 71 Driving state determination means 72 Intake adjustment unit 73 Speed ​​control section 81, 82 Pressure detection means 83 Discharge temperature detection means 100 Engine-driven compressor 120 Intake control device 121 Control Channel 122 Pressure Regulating Valve 123 Bypass flow path 124 Start unloader valve 126 Starting load reduction device 140 Compressor body 141 Intake adjustment valve 142 Closed valve pressure chamber 150 Engine 160 Receiver Tank 164 Oil supply channel 165 Oil cooler 166 Oil filter P1 Starting unload pressure P2 rated pressure P3 No-load operation start pressure P4 Transition operation start pressure N1 No-load rotation speed N2 full load rotation speed

Claims

1. An operation control method for an engine-driven compressor includes an engine, a compressor body driven by the engine, and an intake control valve that controls intake air to the compressor body by opening and closing an intake port of the compressor body, and transitions between a full-load operation in which the intake control valve is fully opened and the engine is operated at a predetermined full-load rotation speed as a target rotation speed, and a no-load operation in which the intake control valve is fully closed and the engine is operated at a no-load rotation speed that is a predetermined rotation speed lower than the full-load rotation speed, When transitioning from the no-load operation to the full-load operation, a transition operation is performed in which the intake control valve is closed and the rotational speed of the engine starts to increase from the no-load rotational speed to the full-load rotational speed as a target rotational speed, The transition operation is performed until a predetermined transition time has elapsed or until the rotation speed of the engine increases to a transition rotation speed that is a predetermined higher rotation speed than the no-load rotation speed, and after the transition operation is completed, the intake control valve is opened to transition to the full load operation.

2. After the engine is started, the intake control valve is fully closed until a predetermined end condition is satisfied, and a warm-up operation is performed, which is the no-load operation with the target rotation speed of the engine set to the no-load rotation speed; and 2. The operation control method for an engine-driven compressor according to claim 1, wherein, after the warm-up operation is terminated as a result of the termination condition being satisfied, the operation is transitioned to the full-load operation when the discharge-side pressure of the compressor body becomes less than a predetermined rated pressure, and the operation is transitioned to the no-load operation when the discharge-side pressure of the compressor body becomes equal to or greater than a no-load operation starting pressure, which is a predetermined higher pressure than the rated pressure, thereby starting normal operation.

3. 3. The operation control method for an engine-driven compressor according to claim 2, wherein the transition operation is executed when transitioning from the no-load operation during the warm-up operation to the full-load operation that is performed in conjunction with the start of the normal operation.

4. 4. The method for controlling operation of an engine-driven compressor according to claim 2, wherein the transition operation is executed when transitioning from the no-load operation to the full-load operation that is performed during the normal operation.

5. a main control flow path communicating between a valve-closing pressure chamber of the intake control valve and a discharge side of the compressor body; a pressure regulating valve that closes the main control flow path when the pressure on the discharge side of the compressor body is lower than the rated pressure, starts to open the main control flow path when the pressure is equal to or higher than the rated pressure, and fully opens the main control flow path when the pressure is equal to or higher than a no-load operation start pressure, which is a predetermined higher pressure than the rated pressure; an auxiliary control flow path that bypasses the pressure regulating valve and communicates between the discharge side of the compressor body and the closed valve pressure receiving chamber of the intake regulating valve; an on-off valve for opening and closing the auxiliary control flow path; the intake control valve is closed during the warm-up operation by opening the on-off valve of the auxiliary control flow path, and the normal operation can be performed by the main control flow path by closing the on-off valve of the auxiliary control flow path; After the warm-up operation is completed, the on-off valve of the auxiliary control flow path is kept open until the transition operation is completed, thereby keeping the intake adjustment valve in a closed state during the transition operation, and 4. The method for controlling operation of an engine-driven compressor according to claim 2, wherein, when the transitional operation is completed, the on-off valve of the auxiliary control flow path is closed to start the normal operation.

6. during the normal operation performed with the on-off valve of the auxiliary control flow path closed, when the pressure on the discharge side of the compressor body drops from a pressure equal to or higher than the no-load operation start pressure to a predetermined transition operation start pressure which is a pressure lower than the no-load operation start pressure, the on-off valve of the auxiliary control flow path is opened and the transition operation is started with the intake adjustment valve closed, 6. The method for controlling operation of an engine-driven compressor according to claim 5, wherein, when the transition operation is completed, the on-off valve of the auxiliary control flow path is closed to transition to the full load operation.

7. An engine-driven compressor includes an engine, a compressor body driven by the engine, and an intake regulating valve that controls intake of the compressor body by opening and closing an intake port of the compressor body, and is equipped with operation control means that transitions between a full-load operation in which the intake regulating valve is fully opened and the engine is operated at a predetermined full-load rotation speed as a target rotation speed, and a no-load operation in which the intake regulating valve is fully closed and the engine is operated at a no-load rotation speed that is a predetermined rotation speed lower than the full-load rotation speed, The operation control means When transitioning from the no-load operation to the full-load operation, a transition operation is performed in which the intake control valve is closed and the rotational speed of the engine starts to increase from the no-load rotational speed to the full-load rotational speed as a target rotational speed, The transition operation is performed until a predetermined transition time has elapsed or until the rotation speed of the engine increases to a transition rotation speed that is a predetermined higher rotation speed than the no-load rotation speed, After the transition operation is completed, the intake control valve is opened to transition to the full load operation.

8. The operation control means includes an operation state determination means, After the engine is started, the intake control valve is fully closed until the operating state determination means determines that a predetermined termination condition is satisfied, and a warm-up operation is performed, which is the no-load operation in which a target rotation speed of the engine is set to the no-load rotation speed; and 8. The engine-driven compressor according to claim 7, wherein when the operating state determination means determines that the termination condition is satisfied, the warm-up operation is terminated, and thereafter, normal operation is started, in which the full-load operation is performed when the discharge-side pressure of the compressor body is lower than a predetermined rated pressure, and the no-load operation is performed when the discharge-side pressure is equal to or higher than a no-load operation starting pressure which is a predetermined higher pressure than the rated pressure.

9. The operation control means 9. The engine-driven compressor according to claim 8, wherein the transition operation is performed when transitioning from the no-load operation during the warm-up operation to the full-load operation that is performed when the normal operation starts.

10. The operation control means 10. The engine-driven compressor according to claim 8, wherein the transition operation is performed when transitioning from the no-load operation to the full-load operation that is performed during the normal operation.

11. the operation control means includes an intake control device that controls the opening and closing operation of the intake adjustment valve, The intake control device a main control flow path communicating between a valve-closing pressure chamber of the intake control valve and a discharge side of the compressor body; a pressure regulating valve that closes the main control flow path when the pressure on the discharge side of the compressor body is lower than the rated pressure, starts to open the main control flow path when the pressure is equal to or higher than the rated pressure, and fully opens the main control flow path when the pressure is equal to or higher than a no-load operation start pressure, which is a predetermined higher pressure than the rated pressure; an auxiliary control flow path that bypasses the pressure regulating valve and communicates between the discharge side of the compressor body and the closed valve pressure receiving chamber of the intake regulating valve; a solenoid valve that opens and closes the auxiliary control flow path; a controller for controlling the operation of the solenoid valve; The solenoid valve of the auxiliary control flow path is opened to close the intake control valve during the warm-up operation, and the solenoid valve of the auxiliary control flow path is closed to enable the normal operation to be performed by the main control flow path, After the warm-up operation is completed, the solenoid valve of the auxiliary control flow path is kept open until the transition operation is completed, thereby keeping the intake adjustment valve in a closed state during the transition operation.

10. The engine-driven compressor according to claim 8, wherein, when the transitional operation is completed, the solenoid valve of the auxiliary control flow path is closed to start the normal operation.

12. a pressure detecting means for detecting the pressure on the discharge side of the compressor body; The intake control device includes: during the normal operation performed with the auxiliary control flow path closed, when the pressure on the discharge side of the compressor body detected by the pressure detection means drops from a pressure equal to or higher than the no-load operation start pressure to a predetermined transition operation start pressure which is a pressure lower than the no-load operation start pressure, the solenoid valve of the auxiliary control flow path is opened and the transition operation is started with the intake adjustment valve closed, 12. The engine-driven compressor according to claim 11, wherein the solenoid valve in the auxiliary control flow path is closed when the transition operation is completed.

13. the operation control means includes an intake control device that controls the opening and closing operation of the intake adjustment valve, The intake control device a control flow path communicating between a closing valve pressure chamber of the intake adjustment valve and a discharge side of the compressor body; a variable valve that changes the flow area of ​​the control flow path between fully open and fully closed; a pressure detection means for detecting the discharge side pressure of the compressor body; and 10. The engine-driven compressor according to claim 8, further comprising a controller that controls the operation of the variable valve based on a detection signal from the pressure detection means.

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