Solenoid valve controller of internal combustion engine

Abstract

To provide a solenoid valve controller of an internal combustion engine capable of suppressing generation of wear or noise due to opening / closing of a valve.SOLUTION: When controlling a fuel pressure within a range lower than a fuel pressure when a valve of a shutoff valve disposed in a fuel supply system of a hydrogen engine is maintained in a full lift state, a solenoid valve controller controls at least one of a value of a current supplied to a solenoid coil and an energization time according to at least one of a fuel pressure difference between upstream and downstream of the shutoff valve and a fuel temperature so that the valve is opened or closed within a range in which it does not fully lift.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a control device for an electromagnetic valve provided in an internal combustion engine, typically a gas engine. [Background technology]

[0002] Conventionally, in a gas engine that uses gas such as hydrogen as fuel, a pressure reducing valve is provided in a fuel supply pipe extending from a fuel tank to a delivery pipe in a fuel supply system. Patent Document 1 discloses a configuration in which a pressure reducing valve is provided in a fuel supply pipe to reduce the pressure of the fuel supplied to a fuel injection valve (hereinafter, sometimes referred to as the supply fuel pressure). In general, this pressure reducing valve is of a mechanical type, and the supply fuel pressure is fixed to a constant value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-56380 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the case where the supply fuel pressure is fixed to a constant value by the pressure reducing valve, there are the following problems. That is, if the supply fuel pressure fixed by the pressure reducing valve is specified as a pressure (relatively high pressure) suitable for the case where the fuel injection amount into the combustion chamber is the maximum injection amount (so-called WOT), it becomes difficult to sufficiently improve the accuracy of the fuel injection amount when the injection amount is the minimum injection amount (so-called idling). On the other hand, if the supply fuel pressure fixed by the pressure reducing valve is specified as a pressure (relatively low pressure) suitable for the case where the injection amount is the minimum injection amount, there is a risk that the fuel injection amount when the maximum injection amount is required cannot be obtained sufficiently. For this reason, it is preferable to make the supply fuel pressure variable in order to obtain an appropriate fuel injection amount when the fuel injection amount into the combustion chamber is the maximum injection amount and when the fuel injection amount is the minimum injection amount.

[0005] As a means for satisfying this requirement, it is conceivable to provide a solenoid valve in the fuel supply pipe and adjust the supply fuel pressure by switching the solenoid valve between open and closed (alternately switching between a fully open state and a fully closed state). In the case of a configuration provided with such a solenoid valve, during idling operation, the fully open state and the fully closed state of the solenoid valve are alternately switched between in a short period of time to adjust the delivery pressure to a predetermined range (a range suitable for idling operation). In general, the drive current applied to the solenoid valve is set to fully open the solenoid valve. Therefore, in particular, in an operating state in which the fully open state and the fully closed state of the solenoid valve are alternately switched between in a short period of time, there is a concern that the valve body of the solenoid valve may wear out or generate abnormal noise due to a collision caused when the valve body is fully lifted, and there is room for improvement.

[0006] The present invention has been made in consideration of the above-mentioned points, and an object of the present invention is to provide an electromagnetic valve control device for an internal combustion engine that can suppress wear and abnormal noise caused by the opening and closing drive of the electromagnetic valve. [Means for solving the problem]

[0007] The solution of the present invention for achieving the above object is directed to an electromagnetic valve control device for an internal combustion engine that is arranged in a fuel supply system of the internal combustion engine and controls a solenoid valve whose open / close state is changed by moving a valve element according to a current supply state to an electromagnetic coil. The solenoid valve control device for an internal combustion engine is characterized in that it includes a current control unit that controls at least one of a value of a current supplied to the electromagnetic coil and a time of current supply to the electromagnetic coil according to at least one of a fuel pressure difference upstream and downstream of the solenoid valve and a fuel temperature so that the valve element is opened or closed in a range where the valve element does not fully lift when controlling the supply fuel pressure in a range lower than the supply fuel pressure when the valve element is maintained in a full lift state.

[0008] This specification allows the valve disc of the solenoid valve to be controlled in an open / closed state within a range where it does not fully lift by controlling at least one of the current value and current duration to the solenoid coil in response to the fuel pressure difference and fuel temperature upstream and downstream of the solenoid valve, which affect the movement of the valve disc. This makes it possible to suppress wear on the valve disc and the generation of abnormal noise caused by collision when the valve disc is fully lifted. Effect of the Invention

[0009] In the present invention, when controlling the fuel supply pressure in a range lower than the fuel supply pressure when the valve element of a solenoid valve arranged in a fuel supply system of an internal combustion engine is maintained in a full lift state, at least one of the value of the current supplied to the solenoid coil and the energization time is controlled in accordance with at least one of the fuel pressure difference upstream and downstream of the solenoid valve and the fuel temperature so that the valve element is in an open / closed state in a range in which the valve element does not fully lift. This makes it possible to suppress wear on the valve element and the generation of abnormal noise caused by collision when the valve element is fully lifted. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a shutoff valve provided in a fuel supply system of a hydrogen engine according to an embodiment of the present invention. [Diagram 2] FIG. 2(a) is a diagram showing an example of a change in excitation current to an electromagnetic solenoid in an embodiment and an accompanying change in delivery pressure, and FIG. 2(b) is an enlarged diagram showing the area surrounded by a dashed line in FIG. 2(a). [Diagram 3] FIG. 3(a) is a flowchart showing the procedure for shutoff valve current control, FIG. 3(b) is a diagram corresponding to FIG. 2(b) for a first modified example, and FIG. 3(c) is a diagram corresponding to FIG. 2(b) for a second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the present invention will be described as being applied to a hydrogen engine (an internal combustion engine that uses hydrogen gas as fuel) mounted on a vehicle.

[0012] The fuel supply system of the hydrogen engine according to this embodiment includes a hydrogen storage tank, a fuel supply pipe, a delivery pipe, and an injector for each cylinder (not shown). The hydrogen storage tank is a tank for storing hydrogen under high pressure. The fuel supply pipe is provided with a shutoff valve (electromagnetic valve) 1 (see FIG. 1) for adjusting the pressure of the fuel supplied to the delivery pipe. Hereinafter, the fuel supply pipe upstream of the shutoff valve 1 (hydrogen storage tank side) will be referred to as the upstream fuel supply pipe, and the fuel supply pipe downstream of the shutoff valve 1 (delivery pipe side) will be referred to as the downstream fuel supply pipe. The delivery pipe is provided with a pressure sensor for detecting the pressure of hydrogen gas in the delivery pipe, and a temperature sensor for detecting the temperature of hydrogen gas in the delivery pipe. In addition to the shutoff valve 1, the fuel supply pipe is provided with a pressure reducing valve for reducing the pressure of hydrogen gas and a relief valve that opens when the fuel pressure inside the fuel supply pipe exceeds a predetermined value.

[0013] Next, the configuration of the shutoff valve 1 will be described. Fig. 1 is a cross-sectional view of the shutoff valve 1. In the following description, the left side in Fig. 1 will be referred to as the base end side, and the right side as the tip end side. As shown in Fig. 1, the shutoff valve 1 has a drive unit 2 equipped with an electromagnetic solenoid 21 and arranged on the base end side, and a pressure adjustment unit 3 capable of adjusting the supplied fuel pressure by driving the drive unit 2 and arranged on the tip side.

[0014] The drive unit 2 has a configuration in which an electromagnetic solenoid 21 is housed in a drive unit side casing 22 .

[0015] The drive unit side casing 22 includes a casing body 23 configured by integrally assembling a plurality of members, and a spring receiving member 24 bolted to the base end side of the casing body 23. The electromagnetic solenoid 21 includes a core material 21a and a solenoid coil (electromagnetic coil) 21b made of a conducting wire wound around the outer periphery of the core material 21a, and generates an electromagnetic force when a current is passed through the solenoid coil 21b. The magnitude of this electromagnetic force can be adjusted according to the value of the current (supply current value) passed through the solenoid coil 21b.

[0016] The pressure adjustment unit 3 includes a pressure adjustment unit side casing 31 , a pilot valve (valve body) 32 and a main valve 33 .

[0017] The pressure adjusting unit side casing 31 is integrally attached to the drive unit side casing 22 via a seal member 11, and a hydrogen gas flow space is formed therein. This hydrogen gas flow space has a fuel introduction space 31a connected to the upstream fuel supply pipe, and a fuel discharge space 31b connected to the downstream fuel supply pipe. Therefore, when at least one of the pilot valve 32 and the main valve 33 is in an open state, the fuel introduction space 31a and the fuel discharge space 31b communicate with each other, and hydrogen gas supplied from the hydrogen storage tank and depressurized by the pressure reducing valve passes through the shutoff valve 1 and is introduced into the delivery pipe.

[0018] The pilot valve 32 is a valve that can be moved by the electromagnetic force of the electromagnetic solenoid 21, and a part of it is inserted inside the core material 21a of the electromagnetic solenoid 21. A spring accommodating recess 32a is formed at the base end of the pilot valve 32. A spring 32b accommodated in the spring accommodating recess 32a is compressed between the bottom surface of the spring accommodating recess 32a and the spring receiving member 24, and applies a biasing force in the valve closing direction to the pilot valve 32. In other words, when the solenoid coil 21b of the electromagnetic solenoid 21 is not energized and no electromagnetic force is generated, the pilot valve 32 moves in the valve closing direction due to the biasing force of the spring 32b, whereas when the solenoid coil 21b of the electromagnetic solenoid 21 is energized and an electromagnetic force is generated, the pilot valve 32 moves in the valve opening direction against the biasing force of the spring 32b.

[0019] A tip portion 32g of the pilot valve 32 is inserted into a base end portion of the main valve 33 and is capable of moving within a predetermined movable range relative to the main valve 33. Below, the configurations of the tip portion 32g of the pilot valve 32 and the main valve 33, as well as the assembly state of these valves 32, 33 will be described.

[0020] The main valve 33 includes a generally disk-shaped tip portion 33a and a pilot valve insert portion 33b extending cylindrically from the outer edge of the tip portion 33a toward the base end. The tip portion 32g of the pilot valve 32 is inserted into the pilot valve insert portion 33b.

[0021] A fuel passage 33c extending in a direction along the axis of the main valve 33 is provided in the tip 33a of the main valve 33. One end of the fuel passage 33c is open to the space inside the pilot valve insertion portion 33b, and the other end is open to the fuel discharge space 31b. The pilot valve insertion portion 33b of the main valve 33 is also formed with a through hole 33d that penetrates the pilot valve insertion portion 33b in the radial direction. As a result, the space inside the pilot valve insertion portion 33b and the fuel introduction space 31a are communicated with each other through the through hole 33d. The fuel passage 33c and the through hole 33d serve as a passage for hydrogen gas when the pilot valve 32 is opened, as described later. For this reason, the inner diameter dimensions of the fuel passage 33c and the through hole 33d are determined according to the fuel supply pressure required when the pilot valve 32 is opened.

[0022] An annular recess 33e is formed on the end surface on the tip side of the tip portion 33a of the main valve 33, and a first seal member 33f made of rubber is attached to the recess 33e. When the main valve 33 is in a closed state, the first seal member 33f of the main valve 33 abuts against the opening edge of the fuel outlet space 31b to isolate the fuel introduction space 31a from the fuel outlet space 31b. A recess 32c is formed on the tip portion 32g of the pilot valve 32, and a cylindrical second seal member 32d made of rubber is attached to the recess 32c. When the pilot valve 32 is in a closed state, the second seal member 32d of the pilot valve 32 abuts against the opening edge of the fuel passage 33c of the main valve 33 to isolate the space inside the pilot valve insertion portion 33b from the fuel passage 33c.

[0023] In addition, the pilot valve insertion portion 33b of the main valve 33 has pin insertion holes 33g, 33g formed on each of the opposing surfaces. A pin 32e extending in a direction perpendicular to the axis of the pilot valve 32 is attached to the tip portion 32g of the pilot valve 32. Specifically, a through hole penetrating in the radial direction is formed in the tip portion 32g of the pilot valve 32, and the pin 32e is inserted into this through hole. The inner diameter of the through hole and the outer diameter of the pin 32e are approximately equal. The length of the pin 32e is set to be slightly longer than the outer diameter of the tip portion 32g of the pilot valve 32. Both end portions of the pin 32e (portions protruding from the outer surface of the pilot valve 32) are inserted into the pin insertion hole 33g. The outer diameter of the pin 32e is set to be smaller than the inner diameter of the pin insertion hole 33g. Therefore, the pilot valve 32 is capable of moving relative to the main valve 33 (relative movement in the direction along the axis) by an amount equal to the difference between the outer diameter of the pin 32e and the inner diameter of the pin insertion hole 33g.

[0024] Specifically, when the main valve 33 and the pilot valve 32 are both in a closed state, a predetermined distance is provided between the surface of the outer surface of the pin 32e facing the base end side and the inner surface of the pin insertion hole 33g that faces this surface. Therefore, when the pilot valve 32 moves due to the electromagnetic force of the electromagnetic solenoid 21, if the amount of movement is equal to or less than the above-mentioned predetermined amount, the pin 32e does not apply an operating force (an operating force in the valve opening direction for the main valve 33) to the inner surface of the pin insertion hole 33g. Therefore, only the pilot valve 32 is in an open state. In this state, the hydrogen gas that has flowed into the fuel introduction space 31a from the upstream fuel supply pipe is led out to the downstream fuel supply pipe through the through hole 33d, the space inside the pilot valve insertion part 33b, the fuel passage 33c, and the fuel lead-out space 31b.

[0025] On the other hand, when the electromagnetic force of the electromagnetic solenoid 21 becomes large and the movement amount of the pilot valve 32 exceeds the above-mentioned predetermined amount, the pin 32e applies an operating force to the inner surface of the pin insertion hole 33g, and the electromagnetic force of the electromagnetic solenoid 21 is also transmitted to the main valve 33. As a result, the main valve 33 is opened (the main valve 33 is raised). Before the main valve 33 opens, the pilot valve 32 is already in an open state and the pressure difference between the fuel introduction space 31a and the fuel discharge space 31b (the pressure difference between the front and rear of the main valve 33) is small, so that the main valve 33 can be opened with a relatively small electromagnetic force. In this state, the hydrogen gas that has flowed into the fuel introduction space 31a from the upstream fuel supply pipe passes through a gap formed between the main valve 33 and the pressure adjustment unit side casing 31, passes through the fuel discharge space 31b, and is discharged to the downstream fuel supply pipe. In this case, the cross-sectional area of ​​the gap formed between the main valve 33 and the pressure regulating unit casing 31 is larger than the cross-sectional area of ​​the hydrogen gas flow path (e.g., the cross-sectional area of ​​the fuel passage 33c) when only the pilot valve is open. Therefore, the amount of fuel supplied to the delivery pipe is set to a relatively large flow rate, thereby making the supply fuel pressure relatively high.

[0026] Next, the operation of the shutoff valve 1 configured as described above will be described. As described above, in a hydrogen engine, in order to obtain an appropriate fuel injection amount when the fuel injection amount into the combustion chamber is the maximum injection amount and when the fuel injection amount is the minimum injection amount, it is preferable to make the supply fuel pressure variable. The shutoff valve 1 in this embodiment is configured to make the supply fuel pressure variable by controlling the excitation current to the electromagnetic solenoid 21 to switch between a state in which only the pilot valve 32 is opened and a state in which the main valve 33 is opened. For example, when the accelerator pedal depression amount detected by the accelerator pedal position sensor is zero and the engine is in an idling operation state, the excitation current is made relatively low to open only the pilot valve 32, thereby setting the supply fuel pressure low, thereby making it possible to improve the accuracy of the fuel injection amount. On the other hand, when the accelerator pedal depression amount detected by the accelerator pedal position sensor is large, for example, during WOT, the excitation current is made relatively high to open the main valve 33, thereby setting the supply fuel pressure high, thereby making it possible to obtain a sufficient fuel injection amount.

[0027] FIG. 2(a) shows an example of a change in the supply current (excitation current for switching between opening and closing the pilot valve 32 and the main valve 33) to the electromagnetic solenoid 21 of the shutoff valve 1 according to this embodiment, and a change in the delivery pressure associated therewith. Specifically, FIG. 2(a) shows an example of a case in which the vehicle moves from normal driving (period Tm1 in the figure) after starting to drive, through a deceleration period (period Tm2 in the figure), to idling driving (period Tm3 in the figure), and then through an acceleration period (period Tm4 in the figure), to returning to normal driving (period Tm5 in the figure). As shown in FIG. 2(a), during idling driving, only the pilot valve 32 is opened by alternately switching ON / OFF of the excitation current in a short period of time. As a result, fuel is supplied to the delivery pipe at a relatively small flow rate, and the supply fuel pressure is set low, thereby making it possible to improve the accuracy of the fuel injection amount. On the other hand, during WOT, the excitation current is made relatively high to open the main valve 33. As a result, fuel is supplied to the delivery pipe at a relatively large flow rate, and the supply fuel pressure is set high, thereby making it possible to obtain a sufficient amount of fuel injection.

[0028] Next, a control system for the shutoff valve 1 will be described. The shutoff valve 1 is controlled by an ECU (not shown). Connected to the ECU are a water temperature sensor (a sensor that detects the temperature of engine coolant), a crank angle sensor, an air flow meter, an intake air temperature sensor, the pressure sensor (a sensor that detects the pressure of hydrogen gas in the delivery pipe), the temperature sensor (a sensor that detects the temperature of hydrogen gas in the delivery pipe), and the like (all not shown). Also connected to the ECU is an accelerator opening sensor (not shown) that outputs a detection signal corresponding to the amount of depression of the accelerator pedal.

[0029] As described above, when the drive current (excitation current) passed through the shutoff valve (solenoid valve) is set to fully open the shutoff valve, particularly in an operating state in which the shutoff valve is alternately switched between fully open and fully closed states within a short period of time, there is a concern that the valve may wear out or produce abnormal noise due to collisions when the shutoff valve is fully lifted.

[0030] In consideration of this, the ECU is provided with a current control section as a functional section realized by a control program. When controlling the supply fuel pressure in a range lower than the supply fuel pressure when the main valve 33 is maintained in a full lift state (for example, the supply fuel pressure during WOT) (for example, when controlling the supply fuel pressure during idling), the current control section controls the value of the current supplied to the solenoid coil 21b and the energization time according to the fuel pressure difference between the upstream and downstream of the cutoff valve 1 and the fuel temperature so that the pilot valve 32 is opened or closed in a range where it does not fully lift.

[0031] Next, a description will be given of the shutoff valve current control, which is a characteristic control of this embodiment. This shutoff valve current control is the control of the value of the current supplied to the solenoid coil 21b and the energization time, which is performed by the current control section.

[0032] Fig. 3(a) is a flowchart showing the procedure for shutoff valve current control. This flowchart is repeatedly executed at predetermined time intervals while the hydrogen engine is operating. First, in step ST1, it is determined whether or not a fuel pressure reduction flag is ON. This fuel pressure reduction flag is turned ON, for example, during idling operation (for example, when the amount of accelerator pedal depression detected by the accelerator position sensor is zero). If the fuel pressure reduction flag is OFF and the determination in step ST1 is NO, normal shutoff valve current control (control according to the required fuel pressure based on the amount of accelerator pedal depression, etc.) is performed.

[0033] On the other hand, if the fuel pressure reduction flag is ON and the determination in step ST1 is YES, the process proceeds to step ST2, where it is determined whether or not the pressure of the hydrogen gas in the delivery pipe (delivery internal pressure) detected by the pressure sensor has decreased to a predetermined lower threshold Pt. This lower threshold Pt can be set arbitrarily. For example, it is set as a value near the lower limit value of the delivery internal pressure at which idling operation can be maintained. If the delivery internal pressure has decreased to the lower threshold Pt and the determination in step ST2 is YES, various state quantities are acquired in step ST3. The state quantities acquired here include the engine cooling water temperature, hydrogen gas temperature (fuel temperature), engine rotation speed, engine output (engine torque), etc. The engine cooling water temperature is acquired by a detection signal from the water temperature sensor. The hydrogen gas temperature is acquired by a detection signal from the temperature sensor. The engine rotation speed is calculated based on the crank angle detection signal from the crank angle sensor. The engine torque is calculated based on a detection signal from a torque sensor or information on the fuel injection amount and fuel injection timing from each injector.

[0034] Then, the process proceeds to step ST4, where the upstream / downstream pressure difference ΔP of the shutoff valve 1 is calculated. The pressure on the upstream side of the shutoff valve 1 used in the calculation of this upstream / downstream pressure difference ΔP can be detected by a fuel pressure sensor disposed on the upstream side of the shutoff valve 1. It can also be estimated from the internal pressure of the hydrogen storage tank. For example, if the pressure reducing valve is of a mechanical type, the upstream pressure of the pressure reducing valve (approximately equal to the internal pressure of the hydrogen storage tank) and the downstream pressure (approximately equal to the pressure on the upstream side of the shutoff valve 1) are balanced with a spring force, making it possible to estimate the upstream pressure from the internal pressure of the hydrogen storage tank. Also, the pressure on the downstream side of the shutoff valve 1 used in the calculation of the upstream / downstream pressure difference ΔP can be the delivery internal pressure detected by a pressure sensor.

[0035] Thereafter, the process proceeds to step ST5, where the temperature Tv of the shutoff valve 1 is calculated. Methods for estimating the temperature Tv of the shutoff valve 1 include estimating the temperature of the shutoff valve 1 based on the hydrogen gas temperature (fuel temperature), the engine coolant temperature, the engine rotation speed, the engine output, and the like. The temperature Tv of the shutoff valve 1 may also be estimated by fitting these state quantities to a map created by a pre-test. Instead of estimating the temperature of the shutoff valve 1, a temperature sensor may be directly attached to the shutoff valve 1 to detect the temperature of the shutoff valve 1.

[0036] In step ST6, a drive current value (supply current value) Ip to be supplied to the solenoid coil 21b is calculated. This drive current value Ip corresponds to the maximum drive current value in one pulse waveform of the excitation current during idling operation in FIG. 2(a). This drive current value Ip is determined as a value at which the pilot valve 32 does not fully lift, according to the upstream / downstream differential pressure ΔP and the temperature Tv of the shutoff valve 1 calculated as described above. Specifically, the pilot valve 32 is more difficult to open as the upstream / downstream differential pressure ΔP is larger, so the drive current value Ip is calculated to be a higher value as the upstream / downstream differential pressure ΔP is larger. In addition, the pilot valve 32 is more difficult to open as the temperature Tv of the shutoff valve 1 is higher (the current value is less likely to rise due to an increase in the resistance value of the solenoid coil 21b), so the drive current value Ip is calculated to be a higher value as the temperature Tv of the shutoff valve 1 is higher. This drive current value Ip is calculated based on a predetermined calculation formula or a map previously set by experiment or simulation.

[0037] In step ST7, the drive time Ti of the solenoid coil 21b (the time during which current is applied to the solenoid coil 21b) is calculated. This drive time Ti corresponds to the continuous current application time in one pulse waveform of the excitation current during idling operation in FIG. 2(a). This drive time Ti is also determined as a value at which the pilot valve 32 does not fully lift according to the upstream-downstream differential pressure ΔP and the temperature Tv of the shutoff valve 1 calculated as described above. Specifically, the pilot valve 32 is more difficult to open as the upstream-downstream differential pressure ΔP is larger, so the drive time Ti is calculated to be longer as the upstream-downstream differential pressure ΔP is larger. In addition, the pilot valve 32 is more difficult to open as the temperature Tv of the shutoff valve 1 is higher, so the drive time Ti is calculated to be longer as the temperature Tv of the shutoff valve 1 is higher. This drive time Ti is also calculated based on a predetermined calculation formula or a map previously set by experiment or simulation.

[0038] After the drive current value Ip and the drive time Ti are calculated in this manner, the process proceeds to step ST8, where the solenoid coil 21b is energized with the drive current value Ip and the drive time Ti.

[0039] 2(b) is an enlarged view of the area surrounded by the dashed line in FIG. 2(a), and shows an example of the change in excitation current and the associated change in delivery pressure when the solenoid coil 21b is energized as described above. As shown in FIG. 2(b), in a situation where the delivery pressure is relatively low at the timing when the solenoid coil 21b is energized (timing t1), current control is performed to set the drive current value (excitation current) Ip to a relatively high value (I1 in the figure) and the drive time Ti to a relatively long value (T1 in the figure) within a range where the pilot valve 32 does not fully lift. On the other hand, in a situation where the delivery pressure is relatively high at the timing when the solenoid coil 21b is energized (timing t2), current control is performed to set the drive current value Ip to a relatively low value (I2 in the figure) and the drive time Ti to a relatively short value (T2 in the figure) within a range where the pilot valve 32 does not fully lift. In addition, the delivery pressure A in FIG. 2(b) is the target delivery pressure during idling operation.

[0040] After the solenoid coil 21b is energized in this manner, the process proceeds to step ST9, where it is determined whether or not the fuel pressure reduction flag has been turned OFF. If the fuel pressure reduction flag is maintained ON and the determination in step ST9 is NO, the process returns to step ST2. On the other hand, if the fuel pressure reduction flag is ON and the determination in step ST9 is YES, the aforementioned shutoff valve current control is terminated. The above operations are repeated during the operation of the hydrogen engine.

[0041] As described above, in this embodiment, when controlling the supply fuel pressure during idling operation, the drive current value (supply current value) Ip to the solenoid coil 21b and the drive time (energization time) Ti are controlled in accordance with the upstream-downstream pressure difference ΔP of the shutoff valve 1 and the temperature Tv of the shutoff valve 1 so that the pilot valve 32 is opened or closed within a range in which it does not fully lift. This makes it possible to suppress wear of the pilot valve 32 and the generation of abnormal noise caused by collision when the pilot valve 32 is fully lifted.

[0042] -Other embodiments- The present invention is not limited to the above-described embodiment, and all modifications and applications within the scope of the claims and equivalents thereto are possible.

[0043] For example, in the above embodiment, the present invention has been described as being applied to a hydrogen engine mounted on a vehicle. However, the present invention is not limited to this, and can also be applied to gas engines used for purposes other than vehicles. Furthermore, the fuel is not limited to hydrogen gas.

[0044] In the above embodiment, the drive current value Ip and the drive time Ti to the solenoid coil 21b are controlled according to the upstream / downstream pressure difference ΔP of the shutoff valve 1 and the temperature Tv of the shutoff valve 1. The present invention is not limited to this, and the drive current value Ip may be controlled with the drive time Ti constant, or the drive current value Ip may be controlled with the drive time Ti constant. Fig. 3(b) is a diagram equivalent to Fig. 2(b) in the former case (first modified example) (the drive time Ti is constant at T3 in the diagram), and Fig. 3(c) is a diagram equivalent to Fig. 2(b) in the latter case (second modified example) (the drive current value Ip is constant at I3 in the diagram). [Industrial Applicability]

[0045] The present invention is applicable as a control device for a shutoff valve provided in a hydrogen engine. [Explanation of symbols]

[0046] 1...Shut-off valve (solenoid valve) 21b...Solenoid coil (electromagnetic coil) 32...Pilot valve (valve body)

Claims

[Claim 1] A solenoid valve control device for an internal combustion engine, which controls a solenoid valve that is disposed in a fuel supply system of the internal combustion engine and whose open / close state is changed by moving a valve body in response to a current supply state to an electromagnetic coil, a current control unit that controls at least one of a value of current supplied to the electromagnetic coil and a current flow time in accordance with at least one of a fuel pressure difference upstream and downstream of the solenoid valve and a fuel temperature so that the valve is opened or closed in a range in which the valve body does not fully lift, when controlling the supply fuel pressure in a range lower than the supply fuel pressure when the valve body is maintained in a full lift state.

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