Solenoid valve drive device

Abstract

To provide a solenoid valve drive device that achieves both suppression of collisions and good valve opening response at the time when the valve is opened.SOLUTION: An ECU serving as a solenoid valve drive device comprises a valve-opening current acquisition unit, a first duty control unit, and a second duty control unit. The valve-opening current acquisition unit acquires a valve-opening current value (valve-opening-time current X2) which is an amount of a current flowing through an electromagnetic coil when the valve is open. The first duty control unit executes duty control with an initial duty value Dini during an initial period from when energization starts to when the valve is opened. The second duty control unit gradually increases a duty value from the initial duty value Dini by a predetermined additional amount Dadd during a valve open period including valve opening timing t22 after the initial period. The larger the acquired valve-opening-time current X2 is, the larger the initial duty value Dini is changed to be. The additional amount Dadd is to be set to a value smaller than the initial duty value Dini.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The disclosure herein relates to a solenoid valve driver. [Background technology]

[0002] The solenoid valve drive device described in Patent Document 1 performs duty control on the amount of current supplied to the electromagnetic coil. Specifically, when closing the valve disc, the duty ratio is not suddenly set to zero, but is gradually reduced. This prevents the valve disc from colliding forcefully with the valve seat when the valve is closed, thereby extending the life of the valve disc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-156305 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the above-described control of gradually changing the duty ratio is also applied to the valve opening operation to prevent a collision when the valve is opened, the following problem arises. That is, when the valve is opened, there is a time lag between when the electromagnetic coil starts to be energized and when the valve element actually starts to open the valve. That is, it takes time for the energizing current to increase from the start of energization to the current value required to start opening the valve. If this time is long, the responsiveness of the valve opening deteriorates. Therefore, if an attempt is made to prevent a collision when the valve is opened by gradually increasing the duty ratio, the responsiveness of the valve opening deteriorates.

[0005] One disclosed object is to provide a solenoid valve drive device that achieves both suppression of collisions when the valve is opened and good valve opening responsiveness. [Means for solving the problem]

[0006] In order to achieve the above object, an electromagnetic valve drive device according to one aspect of the present disclosure includes: A solenoid valve drive device is applied to a solenoid valve (17) including a valve element (17a) that opens and closes a fluid passage (16) and an electromagnetic coil (17b) that exerts an electromagnetic force to open the valve element, and the solenoid valve drive device opens the valve by duty-controlling the amount of current supplied to the electromagnetic coil, a valve opening current acquisition unit (S16) that acquires a valve opening current value that is the amount of current flowing through the electromagnetic coil when the valve is opened; a first duty control unit (S33) that executes duty control with an initial duty value (Dini) during an initial period from the start of energization until before the valve is opened; and a second duty control unit (S34) that executes duty control so as to gradually increase the duty value by a predetermined additional amount (Dadd) from the initial duty value during a valve opening period including the valve opening timing after the initial period. The larger the acquired valve-opening current value, the larger the initial duty value is changed to. The additional amount is set to a value smaller than the initial duty value.

[0007] According to the above-described solenoid valve drive device, the larger the acquired valve-opening current value, the larger the initial duty value Dini is changed to. Therefore, the initial duty value Dini can be set to a duty value that is as large as possible without opening the valve. This increases the gradient of the current flow, thereby shortening the time required to open the valve. In other words, the responsiveness of the valve opening can be improved.

[0008] Furthermore, the additional amount Dadd is set to a value smaller than the initial duty value Dini. Therefore, by gradually increasing the duty value by the additional amount Dadd, the rate of increase in the amount of energization can be made smaller. This makes it possible to prevent the valve disc from colliding strongly when the valve is opened. This makes it possible to extend the life of the solenoid valve. In short, it is possible to reduce the impact when the valve is opened without impairing responsiveness, thereby achieving both improved responsiveness and a longer life for the solenoid valve.

[0009] The reference numbers in parentheses above merely indicate an example of the correspondence with specific configurations in the embodiments described below, and do not in any way limit the technical scope. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram of a fuel cell system to which a solenoid valve drive device according to a first embodiment is applied. [Figure 2] FIG. 2 is a schematic diagram of the electromagnetic valve driving device shown in FIG. [Figure 3] FIG. 10 is a diagram showing the time transition of the command duty and current. [Figure 4] 10 is a flowchart showing the procedure of an initial valve opening control that also serves as a primary check. [Figure 5] 10 is a flowchart showing the procedure of second and subsequent valve opening control. [Figure 6] 10 is a map in which duty values ​​for each voltage used in valve opening control are stored. [Figure 7] FIG. 6 is a schematic diagram of an electromagnetic valve drive device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, several embodiments will be described with reference to the drawings. Note that, in each embodiment, corresponding components are denoted by the same reference numerals, and redundant description may be omitted.

[0012] (First embodiment) The fuel cell system shown in Figure 1 includes an FC stack 10, a hydrogen tank 11, a compressor 12, a gas-liquid separator 13, a hydrogen injector 14, an air supply valve 15, an exhaust drain valve 17, and an ECU 30. ECU stands for Electronic Control Unit, and is an electronic control device. The fuel cell system is installed in a vehicle.

[0013] The FC stack 10, which is a fuel cell stack, is the power source for the drive motor installed in the vehicle. The FC stack 10 generates electricity by causing a chemical reaction between fuel and an oxidant and converting it into electrical energy. In the example of Figure 1, hydrogen is used as the fuel and oxygen from the air is used as the oxidant. A hydrogen tank 11 stores hydrogen in a compressed state and supplies it to the FC stack 10. A compressor 12 compresses air and supplies it to the FC stack 10.

[0014] The gas-liquid separator 13 separates the liquid and gas discharged from the FC stack 10. The main liquid discharged from the FC stack 10 is water, which is produced by the chemical reaction in the FC stack 10. The main gases discharged from the FC stack 10 are the excess hydrogen supplied and air. The excess hydrogen is supplied again to the FC stack 10. Exhaust gas and wastewater other than hydrogen are discharged from the discharge passage 16.

[0015] The hydrogen injector 14 is provided in the hydrogen supply path from the hydrogen tank 11 to the FC stack 10. When the hydrogen injector 14 opens, the compressed and stored hydrogen is injected towards the FC stack 10. The amount of hydrogen supplied to the FC stack 10 is controlled by controlling the open time and current value of the hydrogen injector 14. The air supply valve 15 is provided in the air supply path from the compressor 12 to the FC stack 10. When the air supply valve 15 opens, compressed air is supplied towards the FC stack 10. The amount of air supplied to the FC stack 10 is controlled by controlling the open angle of the air supply valve 15.

[0016] The exhaust and drain valve 17 is provided in the exhaust passage 16. When the exhaust and drain valve 17 opens, air is exhausted and drained from the exhaust passage 16. By draining the air, water produced by the power generation by the FC stack 10 is released from the FC stack 10. By exhausting the air, the pressure inside the FC stack 10 is adjusted to an appropriate pressure. The exhaust passage 16 corresponds to a fluid passage that is opened and closed by the exhaust and drain valve 17. The exhaust and drain valve 17 has a valve element 17a and an electromagnetic coil 17b (see Figure 2). When energized, the electromagnetic coil 17b generates an electromagnetic force, which opens the valve element 17a. When energized, the elastic force of an elastic member (not shown) closes the valve element 17a.

[0017] 2, the ECU 30 includes a microcomputer (microcomputer 31), a semiconductor switch 32, an IPD 33, a thermistor 34, a timer 35, and a voltage detection circuit 36. The ECU 30 controls the energization state of the compressor 12, the air supply valve 15, the hydrogen injector 14, the air supply valve 15, etc., thereby controlling the operation of the fuel cell system.

[0018] The microcomputer 31 includes a processor 31a and a memory 31b. The processor 31a controls the various energization states described above in accordance with a program stored in the memory 31b. The memory 31b also stores a map 31m, which will be described later. The data in the map 31m is rewritable.

[0019] The semiconductor switch 32 is provided on the low potential side of the electromagnetic coil 17b and controls the on / off of current to the electromagnetic coil 17b. The semiconductor switch 32 is PWM controlled by the microcomputer 31. That is, this PWM control controls the duty ratio of the on / off current to the electromagnetic coil 17b. The amount of current is maximum at a duty ratio of 100%, and zero at a duty ratio of 0%. A specific example of the semiconductor switch 32 is a MOSFET.

[0020] The IPD 33 is a semiconductor fuse with a built-in protection circuit. IPD is an abbreviation for Intelligent Power Device. In addition to being a semiconductor fuse, the IPD 33 also has a current detection function. The IPD 33 is provided on the high-potential side of the electromagnetic coil 17b and detects the current value Im (amount of current flowing through the electromagnetic coil 17b). The IPD 33 outputs the detected current value to the microcomputer 31.

[0021] The thermistor 34 is a temperature sensor that detects the ambient temperature of the ECU 30. The thermistor 34 outputs the detected temperature to the microcomputer 31. The timer 35 measures the elapsed time from the previous shutdown of the fuel cell system to the current startup. The timer 35 outputs the measured time to the microcomputer 31 at the timing of startup of the fuel cell system. The voltage detection circuit 36 ​​is a circuit that detects the voltage of the power supply applied to the electromagnetic coil 17b. The voltage detection circuit 36 ​​outputs the detected voltage to the microcomputer 31.

[0022] Next, the opening and closing valve control of the exhaust and drainage valve 17 by the microcomputer 31 will be described. The microcomputer 31 estimates the amount of water produced from the amount of power generated by the FC stack 10. Based on the estimated amount of water produced, the microcomputer 31 controls the timing and duration of opening of the exhaust and drainage valve 17 so that the amount of water in the FC stack 10 is adjusted to an appropriate level. Furthermore, the microcomputer 31 controls the timing and duration of opening of the exhaust and drainage valve 17 so that the pressure in the FC stack 10 is adjusted to an appropriate pressure. The microcomputer 31 also controls the magnitude of the current value Im flowing through the electromagnetic coil 17b and the rate at which the current value Im rises by PWM controlling the semiconductor switch 32.

[0023] There is a time lag between when the electromagnetic coil 17b is energized and when the valve element 17a actually starts to open. That is, it takes time for the energizing current to increase from the start of energization to the current value required to start opening the valve, and this time is the time lag. A long time lag means poor responsiveness between when the microcomputer 31 issues a valve opening command and when the valve actually opens, which hinders the water content and pressure in the FC stack 10 from being adjusted to the appropriate level.

[0024] To shorten the time lag and improve responsiveness, the duty can be increased from the start of energization until the valve opens, thereby accelerating the rate of increase in the current value Im. However, once the valve opens, there is no need to increase the duty. In other words, the current value Im required to maintain the valve element 17a in an open state is smaller than the current value Im required to switch from a closed state to an open state. Therefore, after the valve opens, it is desirable to reduce the current value Im to a maintenance current (DUTY = D2).

[0025] However, since there is variation in the valve opening timing, it is necessary to set the period during which the duty is increased to a longer period with a margin of error. Specific causes of the variation include variations in the individual exhaust drain valves 17 and variations in electrical resistance. Examples of variations in electrical resistance include variations in the length of the wire harness 17w connecting the exhaust drain valve 17 and the ECU 30, variations in the entire system of the power supply path to the exhaust drain valve 17, and variations due to temperature.

[0026] In this way, a margin is provided for the period during which the duty is increased in consideration of variations in valve opening timing, so a large amount of current flows through the electromagnetic coil 17b immediately after the valve opens. This causes the valve element 17a to strongly collide with a stopper (not shown) immediately after the valve opens, accelerating the deterioration of the exhaust drain valve 17 over time. In other words, if the valve is opened with a large amount of current to improve valve opening response, the collision at the time of opening becomes larger. To solve this problem, the ECU 30, which serves as the electromagnetic valve drive device, performs duty control as shown in Figure 3.

[0027] The horizontal axis in Figure 3 represents elapsed time. The vertical axis in the lower part of Figure 3 represents the PWM signal output by microcomputer 31 to the base electrode of semiconductor switch 32. This PWM signal corresponds to the command duty that microcomputer 31 commands semiconductor switch 32 to. The vertical axis in the upper part of Figure 3 represents the current value Im that flows through electromagnetic coil 17b and is detected by IPD 33. The left side of Figure 3 represents the command duty when the valve is opened for the first time after starting up the fuel cell system. The right side of Figure 3 represents the command duty when the valve is opened for the second or subsequent times after starting up the fuel cell system.

[0028] In the initial valve opening control, at time t11, the command duty is set to 100% and current begins to flow. Accordingly, the current value Im rises, and at time t12, when it reaches the current value Iopen required to open the valve, the valve element 17a opens. As the valve opens, an induced current flows momentarily through the electromagnetic coil 17b. Therefore, the waveform of the rising current value Im temporarily drops at the moment the valve opens. Thereafter, the current value Im rises again and saturates at a constant value.

[0029] The time ta from the start of energization at time t11 to the valve opening at time t12 is the time required for the valve to open, and corresponds to the length of the time lag mentioned above. The time tb in Figure 3 is a predetermined time that is sufficient for the current value Im to reach saturation. For example, the time tb is set to 20 ms.

[0030] At time t13 when time tb is reached, the command duty is reduced to D2. The value of D2 is set to the minimum value necessary to maintain the valve element 17a in the open state after the valve is opened. Time tc in FIG. 3 corresponds to the length of the energization time from time t11 when energization starts to time t14 when energization ends. In the initial valve opening control described above, the ECU 30 measures the valve opening current X2, which is the current value Im when the valve is opened (time t12), and the time ta required to open the valve.

[0031] The lower the battery voltage, the slower the rate of increase of the current Im immediately after the start of energization, as shown by the dashed line in Figure 3. Furthermore, the higher the electrical resistance, the slower the rate of increase of the current Im. As a result, the time ta required for the valve to open becomes longer. For example, when the ambient temperature is high, the electrical resistance of the electromagnetic coil 17b increases, and the time ta required for the valve to open becomes longer.

[0032] In the second and subsequent valve opening control operations, at time t21, the command duty is set to the initial duty value Dini and current is applied. Immediately thereafter, the duty value is gradually increased by a predetermined additional amount Dadd. The initial duty value Dini is set to a value smaller than the valve opening current X2. The additional amount Dadd is set to a value smaller than the initial duty value Dini.

[0033] The time interval for increasing the duty value by the additional amount Dadd is set as short as possible. For example, the duty value is increased by the additional amount Dadd every control period (e.g., 4 ms) of the microcomputer 31. The time for maintaining the initial duty value Dini may be the same as or longer than the control period of the microcomputer 31.

[0034] Thereafter, while the duty value is gradually increased by the additional amount Dadd, the valve opens at time t22. As with the initial valve opening control, if a temporary decrease in the waveform of the current value Im is detected, it is determined that the valve has opened. Once the valve is confirmed to be open, at time t23, the increase in the additional amount Dadd is stopped. Thereafter, the command duty (D1) at time t23 is maintained. Thereafter, at time t24, when the aforementioned time tb is reached, the command duty is reduced to D2. Thereafter, at time t25, when the aforementioned time tc is reached, the command duty is set to zero and power is stopped.

[0035] In other words, from the second valve opening control onwards, energization starts with an initial duty value Dini that is set to the largest possible duty value without opening the valve. This increases the slope of the increase in the current value Im, shortening the time ta required for valve opening. In other words, improving the valve opening response. However, during the period before and after the valve opening, including the valve opening time t22, the duty value is gradually increased by the additional amount Dadd, thereby decreasing the slope of the increase in the current value Im. This prevents the valve body 17a from strongly colliding with the stopper.

[0036] Next, the procedure by which the microcomputer 31 executes the above-mentioned valve opening control will be described with reference to FIGS.

[0037] The control shown in FIG. 4 shows the procedure for valve opening control when the valve is opened for the first time after the fuel cell system is started. First, in step S10, it is determined whether the time from the previous system shutdown to the current system startup is sufficiently long. For example, it is determined whether the elapsed time measured by the timer 35 is longer than a predetermined time. If the elapsed time is short, there is a high possibility that the temperature of the exhaust drain valve 17 and the ambient temperature of the thermistor 34 differ greatly. In this case, when a correction is made according to the resistance value of the electromagnetic coil 17b based on the temperature detected by the thermistor 34, the accuracy of the correction will be poor. Therefore, the predetermined time used for the determination in step S10 is set to a length that allows the above-mentioned difference to be considered sufficiently small.

[0038] If it is determined in step S10 that the stop time is sufficiently long, the temperature T2 monitored by the thermistor 34 is stored in the memory 31b in the following step S11. The voltage V2 monitored by the voltage detection circuit 36 ​​is stored in the memory 31b in the following step S12. The semiconductor switch 32 is operated with a duty ratio of 100%, thereby energizing the electromagnetic coil 17b. The current value Im is monitored by the IPD 33 in the following step S14.

[0039] In the next step S15, it is determined whether the current value Im is smaller than the immediately preceding value. If it is determined that it is smaller, it is assumed that the valve is open, as shown at time t12 in FIG. 3. If it is determined that the valve is open, in the next step S16, the valve-open current X2, which is the current value Im when the valve is open, is stored in the memory 31b. In the next step S17, the time ta required for the valve to open is stored in the memory 31b.

[0040] In the next step S18, it is determined whether the aforementioned time tb shown in Figure 3 has elapsed. If it is determined that the time tb has elapsed, the stable current value I2 at that time is stored in memory 31b. In the next step S20, the resistance R is calculated based on the voltage V2 acquired in step S12 and the current I2 acquired in step S19. Specifically, the resistance R is calculated using the formula R = V2 / I2.

[0041] In the following step S19, the resistance R calculated in step S20 is corrected by the temperature T2 stored in step S11. Specifically, the resistance R is corrected to a resistance value at a reference temperature (e.g., 25°C). For example, the resistance R is corrected to a resistance R2 using the formula R2 = R × (1 + α × (25 - T2)), where α is the temperature coefficient of copper, which is the material of the wire harness 17w and the electromagnetic coil 17b. The resistance R represents the resistance value of the entire system. The resistance value of the entire system is mainly determined by the internal resistance of the ECU 30, the wiring resistance of the wire harness 17w, and the resistance of the electromagnetic coil 17b.

[0042] In the following step S22, the values ​​in the map 31m described above are updated as follows based on the valve-opening current X2 stored in step S16 and the resistance value R2 calculated in step S21: As shown in Fig. 6, the map 31m stores values ​​of the initial duty value Dini and the additional amount Dadd corresponding to the power supply voltage.

[0043] Each of the symbols A, B, C, D, and E in Figure 6 indicates the default value Dini1 of the initial duty value Dini for each voltage. Each of the symbols a, b, c, d, and e in Figure 6 indicates the default value Dadd1 of the additional amount Dadd for each voltage. These default values ​​are set assuming that the default resistance value of the entire system is R1 and the default open-valve current is X1. The default resistance value R1 and the default open-valve current X1 are set to their maximum expected values.

[0044] The values ​​obtained by multiplying the ratio of R2 to R1 and the ratio of X2 to X1 by the default values ​​A to E and a to e are used as the updated initial duty value Dini and additional amount Dadd, and the map 31m is rewritten. In other words, the larger the detected resistance value R2, the larger the values ​​of the initial duty value Dini and additional amount Dadd are set to. Also, the larger the detected valve-opening current X2, the larger the values ​​of the initial duty value Dini and additional amount Dadd are set to.

[0045] The default values ​​Dini1 and Dadd1 are set by taking into maximum consideration the expected variations in the resistance value R between machines and the delay due to the reactance of the electromagnetic coil 17b. Therefore, the updated initial duty value Dini and additional amount Dadd are always smaller than the default values.

[0046] The control shown in FIG. 5 shows the procedure for valve opening control when the valve is opened for the second or subsequent time after the fuel cell system is started. First, in step S30, the voltage value is monitored by the voltage detection circuit 36. In the following step S31, the initial duty value Dini2 and additional amount Dadd2 corresponding to the voltage value detected in step S30 are read. For example, when using the map 31m shown in FIG. 6, if the detected voltage value is 14 V, Dini2 = B × (R2 / R1) × (X2 / X1) and Dadd2 = b × (R2 / R1) × (X2 / X1). Note that the initial duty value Dini2 and additional amount Dadd2 indicate updated values. The initial duty value Dini1 and additional amount Dadd1 indicate default values.

[0047] In the next step S32, it is determined whether or not there is a command to energize the electromagnetic coil 17b. If there is a command to energize, in the next step S33, energization begins at the initial duty value Dini2 read in step S31. In the next step S34, the duty ratio is gradually increased by the additional amount Dadd2 read in step S31.

[0048] In the next step S35, it is determined whether the current value of the current value Im is smaller than the immediately preceding value. If it is determined that it is smaller, it is assumed that the valve is open, as shown at time t22 in Figure 3. If it is determined that the valve is open, in the next step S36, the duty value D1 at the time when it was confirmed that the valve was open is maintained.

[0049] In the next step S37, it is determined whether or not a time tb in FIG. 3 has elapsed since the start of energization. If it is determined that the time tb has elapsed, in the next step S38, the command duty is maintained at the value D2 in FIG. 3. In the next step S39, it is determined whether or not a time tc in FIG. 3 has elapsed since the start of energization. If it is determined that the time tc has elapsed, in the next step S40, energization is terminated and the exhaust drain valve 17 is closed.

[0050] If it is determined in step S35 that the current value of the current value Im is not smaller than the immediately preceding value, fail-safe control is executed in the following steps S41, S42, and S43. That is, first in step S41, it is determined whether or not time tb in FIG. 3 has elapsed since the start of energization. If it is determined that time tb has elapsed, the following step S42 increases the command duty by more than the additional amount Dadd. For example, the command duty is increased to 100%, and this state is maintained for time ta.

[0051] In short, a positive determination in step S41 means that it was determined in step S35 that the previous Im was not greater than the current Im, and that time tb had passed in step S41. In other words, even though the command duty continues to be increased by the additional amount Dadd2, the valve still does not open even after time tb has passed. In this case, there is a possibility that some kind of abnormality has occurred, so in step S42 the command duty is set to 100% to attempt to open the valve.

[0052] In the next step S43, the duty values ​​stored in the map 31m are updated to the default values ​​Dini1 and Dadd1. As described above, the default values ​​Dini1 and Dadd1 are set to the maximum possible values, so in step S43 the duty values ​​are increased. In short, when there is a possibility of an abnormality as described above, the duty values ​​are increased from the next time onwards to prevent the recurrence of malfunctions such as valve failure.

[0053] <Summary of the first embodiment> As described above, according to this embodiment, the ECU 30 has a valve-opening current acquisition unit, a first duty control unit, and a second duty control unit. That is, in the initial valve-opening control, the microcomputer 31 acquires, from the IPD 33 in step S16, a valve-opening current value (valve-opening current X2), which is the amount of electricity supplied to the electromagnetic coil 17b when the valve is opened. When this control is being executed, the microcomputer 31 corresponds to the valve-opening current acquisition unit.

[0054] In addition, in the second and subsequent valve opening control, duty control is performed with the initial duty value Dini during the initial period from the start of energization until before the valve opens (step S33). When this control is being performed, the microcomputer 31 corresponds to the first duty control unit.

[0055] In the second and subsequent valve opening control, the duty value is gradually increased from the initial duty value Dini by a predetermined additional amount Dadd during the valve opening period including the valve opening timing (t22) after the initial period (step S34). When this control is being executed, the microcomputer 31 corresponds to the second duty control unit.

[0056] The larger the acquired valve-opening current X2, the larger the initial duty value Dini is changed to. Therefore, the initial duty value Dini for the second and subsequent valve-opening controls can be set to a duty value that is as large as possible without opening the valve. This increases the slope of the increase in the current value Im, thereby shortening the time ta required to open the valve. In other words, the responsiveness of the valve opening can be improved.

[0057] Furthermore, in this embodiment, the additional amount Dadd is set to a value smaller than the initial duty value Dini. Therefore, by gradually increasing the duty value by the additional amount Dadd, the increasing slope of the current value Im can be made smaller. This makes it possible to prevent the valve body 17a from colliding strongly when the valve is opened. This makes it possible to extend the life of the exhaust drain valve 17. In short, it is possible to reduce the impact when the valve is opened without impairing responsiveness, thereby achieving both improved responsiveness and a longer life for the exhaust drain valve 17.

[0058] Furthermore, the ECU 30 of this embodiment includes a valve-opening time acquisition unit and a fail-safe control unit. That is, in the second or subsequent valve-opening control, when the valve is opened after the valve-opening current X2 is acquired, the required time ta from the start of energization to valve opening is acquired (step S17). The microcomputer 31, when executing this control, corresponds to the valve-opening time acquisition unit. Furthermore, if the valve does not open after the upper limit time tb has elapsed despite gradually increasing the duty value by the additional amount Dadd, the required time ta is maintained at 100% duty (step S42). The microcomputer 31, when executing this control, corresponds to the fail-safe control unit. If the valve does not open in this way, it is assumed that some kind of abnormality has occurred, and the command duty is set to 100%. This improves the reliability of valve opening when an abnormality occurs.

[0059] Furthermore, the ECU 30 of this embodiment includes a resistance calculation unit. Specifically, in the initial valve opening control, the resistance value R2 of the entire system is calculated based on the voltage V2 applied to the electromagnetic coil 17b and the following stable current value I2 (step S20). The stable current value I2 is the stabilized amount of current supplied to the electromagnetic coil 17b after the valve is opened. When this control is being executed, the microcomputer 31 corresponds to the resistance calculation unit. Therefore, the initial duty value Dini in the second and subsequent valve opening controls can be set to a duty value that is as large as possible without opening the valve, with high accuracy. This can promote both improved responsiveness and a longer life for the exhaust drainage valve 17.

[0060] Furthermore, in this embodiment, the resistance value is corrected according to the temperature T2 at which the stable current value I2 is obtained, so that the initial duty value Dini can be set to a duty value that is as large as possible without causing the valve to open, with even greater accuracy.

[0061] Furthermore, in this embodiment, the valve-opening current acquisition unit acquires the current value when the amount of current supplied to the electromagnetic coil 17b switches from increasing to decreasing as the valve-opening current X2 (valve-opening current value). This allows the valve opening to be detected with high accuracy. Therefore, the initial duty value Dini can be set to an optimal value with high accuracy.

[0062] Furthermore, in this embodiment, the fluid passage in which the exhaust drain valve 17 is provided is the discharge passage 16 of the fuel cell stack 10. The valve-opening current X2 (valve-opening current value) is acquired the first time the valve is opened after the fuel cell system is started. The initial duty value Dini is set using the valve-opening current X2 acquired the first time from the next time the valve is opened. This reduces the frequency with which the map 31m is updated, and avoids unnecessary rewriting of the memory 31b.

[0063] Furthermore, in this embodiment, the larger the acquired valve-opening current X2, the larger the value of the additional amount Dadd is set to, which reduces the risk of the valve being unable to open due to the additional amount Dadd being set to an excessively small value.

[0064] (Second embodiment) In the present embodiment shown in Fig. 7, the IPD 33 shown in Fig. 2 is replaced with a current detection mechanism 33a. The current detection mechanism 33a is provided on the low-potential side of the electromagnetic coil 17b and detects the value of the current Im (amount of current flowing through the electromagnetic coil 17b). The current detection mechanism 33a includes a shunt resistor and an operational amplifier.

[0065] In this embodiment, the same control as that shown in Figures 4 and 5 is executed. Therefore, this embodiment also achieves the same effects as the first embodiment.

[0066] (Other embodiments) Although multiple embodiments of the present disclosure have been described above, not only the combinations of configurations explicitly stated in the description of each embodiment but also partial combinations of configurations of multiple embodiments can be made without explicit statements, as long as there are no particular problems with the combinations. Furthermore, combinations of configurations described in multiple embodiments and modified examples that are not explicitly stated are also considered to be disclosed by the following description.

[0067] In each of the above embodiments, the exhaust drain valve 17 employed as the solenoid valve controlled by the ECU 30 has both a drain function and an exhaust function. However, the solenoid valve may have either one of the drain or exhaust functions. Furthermore, although the exhaust drain valve 17 shown in FIG. 1 is provided downstream of the gas-liquid separator 13, it may also be provided upstream of the gas-liquid separator 13.

[0068] The ECU 30 in each of the above embodiments has a fail-safe control unit. However, the fail-safe control unit may be eliminated, and control may be performed so as to prohibit the valve from opening when there is a possibility of an abnormality.

[0069] In each of the above-described embodiments, the ECU 30 updates the initial duty value Dini and the additional amount Dadd based on both the resistance value R2 and the valve-opening current X2. Alternatively, the calculation of the resistance value R2 may be eliminated and the initial duty value Dini and the additional amount Dadd may be updated based on the valve-opening current X2.

[0070] In each of the above embodiments, the current value when the amount of current flow switches from increasing to decreasing is acquired as the valve-open current X2. Alternatively, a sensor may be provided to detect valve opening directly, and the current value when the valve opening is detected may be acquired as the valve-open current X2.

[0071] In each of the above embodiments, the solenoid valve of the fuel cell system is the object of control by the ECU 30 (solenoid valve driving device), but the object of control by the ECU 30 is not limited to such a solenoid valve, and solenoid valves of other systems may also be the object of control. [Explanation of symbols]

[0072] 10 fuel cell stack, 16 discharge passage (fluid passage), 17 solenoid valve, 17a valve body, 17b electromagnetic coil, Dadd additional amount, Dini initial duty value, S16 valve opening current acquisition unit, S17 valve opening time acquisition unit, S20 resistance calculation unit, S33 first duty control unit, S34 second duty control unit, S42 fail-safe control unit, ta required time.

Claims

1. A solenoid valve drive device is applied to a solenoid valve (17) including a valve element (17a) that opens and closes a fluid passage (16) and an electromagnetic coil (17b) that exerts an electromagnetic force to open the valve element, and the solenoid valve drive device opens the valve by duty-controlling the amount of current supplied to the electromagnetic coil, a valve-opening current acquisition unit (S16) that acquires a valve-opening current value that is the amount of current flowing through the electromagnetic coil when the valve is opened; a first duty control unit (S33) that executes the duty control with an initial duty value (Dini) during an initial period from the start of energization to before the valve is opened; a second duty control unit (S34) that executes the duty control so as to gradually increase the duty value from the initial duty value by a predetermined additional amount (Dadd) during a valve opening period including a valve opening timing after the initial period; Equipped with The larger the acquired valve-opening current value, the larger the initial duty value is changed to; The additional amount is set to a value smaller than the initial duty value.

2. a valve opening time acquisition unit (S17) that acquires the time (ta) required from the start of energization to the opening of the valve during the valve opening operation when the valve opening current value is acquired; a fail-safe control unit (S42) that, when the valve does not open even after the upper limit time has elapsed despite the duty value being gradually increased by the additional amount from the initial duty value, continues the required time at 100% duty; The electromagnetic valve driving device according to claim 1 , comprising:

3. a resistance calculation unit (S20) that calculates a resistance value of the entire system based on a stable current value, which is a stabilized amount of current supplied to the electromagnetic coil after the valve is opened, and a voltage value applied to the electromagnetic coil; 3. The electromagnetic valve driving device according to claim 1, wherein the initial duty value is changed to a larger value as the calculated resistance value increases.

4. The electromagnetic valve driving device according to claim 3 , wherein the resistance value is corrected in accordance with the temperature at the time when the stable current value is acquired.

5. 3. The electromagnetic valve drive device according to claim 1, wherein the valve-opening current acquisition unit acquires, as the valve-opening current value, a current value at which an amount of current supplied to the electromagnetic coil switches from an increase to a decrease.

6. the fluid passage is a discharge passage of a fuel cell stack (10); the valve opening current value is acquired at the first valve opening operation after a fuel cell system including the fuel cell stack is started up; 3. The electromagnetic valve driving device according to claim 1, wherein the initial duty value is set using the valve-opening current value acquired initially at the next or subsequent valve-opening operation.

7. 3. The electromagnetic valve driving device according to claim 1, wherein the additional amount is set to a larger value as the acquired valve-opening current value increases.

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