Electronic control device

Abstract

To improve the detection accuracy of solenoid valve failure.SOLUTION: An ECU 1 controls a solenoid valve 2 mounted on a vehicle, and includes a shunt resistor 15 and a current detection circuit 16, and a microcomputer 19. The shunt resistor 15 and the current detection circuit 16 detect a regenerated current flowing back to the solenoid valve 2 immediately after the power supply to the solenoid valve 2 is stopped. The microcomputer 19 detects a regenerative current singular point in the time change of the regenerative current. Then, the microcomputer 19 detects sticking failure of the solenoid valve 2 on the basis of the detection result of the regenerative current singular point.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to an electronic control device that controls a solenoid valve.

Background Art

[0002] Patent Document 1 describes a solenoid valve control device that detects a sticking failure of a solenoid valve based on the presence or absence of a singularity at the rising edge of the solenoid valve current flowing through the solenoid valve when driving the solenoid valve.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As a result of the inventors' detailed examination, it has been found that in the technique described in Patent Document 1, there is a problem that a failed solenoid valve is misjudged as normal due to a rapid voltage fluctuation in the DC power supply that supplies the power voltage to the solenoid valve.

[0005] An object of the present disclosure is to improve the detection accuracy of solenoid valve failures.

Means for Solving the Problems

[0006] One aspect of the present disclosure is an electronic control device (1) that controls at least one solenoid valve (2) mounted on a vehicle, the electronic control device (1) including a regenerative current detection unit (15, 16), a regenerative current singularity detection unit (S630), and a regenerative current failure detection unit (S640, S660).

[0007] The regenerative current detection unit is configured to detect a regenerative current that flows back to at least one solenoid valve immediately after the power supply to the at least one solenoid valve is stopped. The regenerative current singularity detection unit is configured to detect a regenerative current singularity, which is a singularity in the temporal change of the regenerative current.

[0008] The regenerative current failure detection unit is configured to detect a sticking failure of at least one solenoid valve based on the detection result by the regenerative current singularity detection unit. The electronic control device of the present disclosure configured as described above detects a regenerative current singularity of the regenerative current that is not affected by voltage fluctuations in the DC power supply. Therefore, the electronic control device of the present disclosure can suppress the occurrence of a situation where a failed solenoid valve is misjudged as normal due to voltage fluctuations in the DC power supply, and can improve the detection accuracy of solenoid valve failures.

[0009] Another aspect of the present disclosure is an electronic control device (1) that controls at least one solenoid valve (2) mounted on a vehicle, including a solenoid valve current detection unit (15, 16), a power supply voltage detection unit (17), a solenoid valve current singularity detection unit (S70, S310), a solenoid valve current failure detection unit (S90, S100, S370, S380), and a failure detection prohibition unit (S40 to S60, S240 to S300).

[0010] The solenoid valve current detection unit is configured to detect a solenoid valve current flowing through at least one solenoid valve after the power supply to the at least one solenoid valve is started. The power supply voltage detection unit is configured to detect the power supply voltage of a DC power supply (4) that supplies the power supply voltage to at least one solenoid valve.

[0011] The solenoid valve current singularity detection unit is configured to detect a solenoid valve current singularity, which is a singularity in the temporal change of the solenoid valve current. The solenoid valve current failure detection unit is configured to detect a sticking failure of at least one solenoid valve based on the detection result by the solenoid valve current singularity detection unit.

[0012] The failure detection prohibition unit determines whether a power supply voltage fluctuation has occurred based on the detection result by the power supply voltage detection unit, and when it is determined that a power supply voltage fluctuation has occurred, prohibits the detection of a sticking failure by the solenoid valve current failure detection unit until a preset prohibition release condition is satisfied.

[0013] The electronic control device of the present disclosure configured as described above prohibits the detection of a sticking failure when a power supply voltage fluctuation occurs. Therefore, the electronic control device of the present disclosure can suppress the occurrence of a situation in which a failed solenoid valve is erroneously determined to be normal due to a voltage fluctuation in the DC power supply, and can improve the detection accuracy of a solenoid valve failure.

[0014] Another aspect of the present disclosure is an electronic control device (1) that controls at least one solenoid valve (2) mounted on a vehicle, including a solenoid valve current detection unit (15, 16), a power supply voltage detection unit (17), a solenoid valve current singularity detection unit (S440), a solenoid valve current failure detection unit (S470, S530), and an invalidation unit (S450, S460).

[0015] The solenoid valve current singularity detection unit is configured to detect a solenoid valve current singularity that is a singularity in the time change of the solenoid valve current. The solenoid valve current failure detection unit is configured to detect a sticking failure of at least one solenoid valve based on the detection result by the solenoid valve current singularity detection unit.

[0016] The invalidation unit determines whether a power supply voltage fluctuation has occurred based on the detection result by the power supply voltage detection unit, and when it is determined that a power supply voltage fluctuation has occurred, invalidates at least the detection result of the solenoid valve current singularity detection unit corresponding to the time point when the power supply voltage fluctuation has occurred.

[0017] The electronic control device of the present disclosure configured as described above invalidates the detection result of the solenoid valve current singularity detection unit when a power supply voltage fluctuation occurs. Therefore, the electronic control device of the present disclosure can suppress the occurrence of a situation where a failed solenoid valve is misjudged as normal due to a voltage fluctuation in the DC power supply, and can improve the detection accuracy of solenoid valve failure.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

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Figure 4

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Figure 8

Figure 9

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Figure 11

Figure 12

Figure 13

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Figure 15

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Figure 17

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Figure 19

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Figure 23

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Figure 25

Embodiments for Carrying Out the Invention

[0019] [First Embodiment] The first embodiment of the present disclosure will be described below with reference to the drawings. The electronic control unit 1 (hereinafter, ECU1) of the present embodiment is mounted on a vehicle and controls the solenoid valve 2 as shown in FIG. 1. ECU is an abbreviation for Electronic Control Unit.

[0020] The solenoid valve 2 includes a solenoid coil 3 and a movable core (not shown). The first end of the solenoid coil 3 is connected to the positive electrode of the vehicle power supply 4, and the second end of the solenoid coil 3 is grounded.

[0021] In the non-energized state where no current flows through the solenoid coil 3 of the solenoid valve 2 in this embodiment, the valve is in a closed state with the valve closed. On the other hand, when the solenoid valve 2 in this embodiment is in an energized state where current flows through the solenoid coil 3, a magnetic attraction force that attracts the movable core is generated, causing the movable core to move and the valve to be in an open state with the valve opened. Note that the solenoid valve 2 may be configured to be in an open state in the above non-energized state and in a closed state in the above energized state. Hereinafter, the state where current flows through the solenoid coil 3 in the solenoid valve 2 is referred to as a valve-energized state, and the state where no current flows through the solenoid coil 3 in the solenoid valve 2 is referred to as a valve-non-energized state.

[0022] The ECU 1 includes a positive terminal 11, a negative terminal 12, a diode 13, a switching element 14, a shunt resistor 15, a current detection circuit 16, a voltage detection circuit 17, a drive circuit 18, and a microcomputer 19.

[0023] The positive terminal 11 is connected to the first end of the solenoid coil 3. The negative terminal 12 is connected to the second end of the solenoid coil 3. The anode of the diode 13 is connected to the negative terminal 12, and the cathode is connected to the positive terminal 11.

[0024] The switching element 14 is a transistor provided on the current conduction path from the solenoid coil 3 to the ground. When the switching element 14 is in the on state, current flows through the above conduction path, and when the switching element 14 is in the off state, no current flows through the above conduction path. Hereinafter, "the switching element 14 is in the on state" is also referred to as "the solenoid valve 2 is in the on state", and "the switching element 14 is in the off state" is also referred to as "the solenoid valve 2 is in the off state".

[0025] The first terminal of the switching element 14 is connected to the negative terminal 12, and the second terminal of the switching element 14 is connected to the first terminal of the shunt resistor 15. Then, the second terminal of the shunt resistor 15 is grounded.

[0026] The current detection circuit 16 detects the voltage across both ends of the shunt resistor 15, and based on this voltage value, detects the current flowing through the solenoid valve 2 (hereinafter referred to as the solenoid valve current). Then, the current detection circuit 16 outputs a current detection signal indicating the detection result of the solenoid valve current to the microcomputer 19.

[0027] The voltage detection circuit 17 detects the voltage at the positive terminal 11 and outputs a voltage detection signal indicating the detection result to the microcomputer 19. Based on the control signal output from the microcomputer 19, the drive circuit 18 outputs a drive signal to the switching element 14 to drive the switching element 14 so that it is in the on state or the off state.

[0028] The microcomputer 19 includes a CPU 21, a ROM 22, and a RAM 23. Various functions of the microcomputer 19 are realized by the CPU 21 executing a program stored in a non-transitory tangible recording medium. In this example, the ROM 22 corresponds to the non-transitory tangible recording medium storing the program. Also, by executing this program, a method corresponding to the program is executed. Note that part or all of the functions executed by the CPU 21 may be configured hardware-wise by one or more ICs or the like.

[0029] The timing chart TC1 in FIG. 2 shows the time changes of the power supply voltage, the solenoid valve voltage, and the solenoid valve current when switching the switching element 14 from the off state to the on state during normal operation of the solenoid valve 2.

[0030] As shown in the timing chart TC1 of FIG. 2, the vehicle power supply 4 constantly outputs a power supply voltage with a voltage value VB. Then, when the switching element 14 switches from the off state to the on state at time t0, the voltage across both ends of the solenoid coil 3 of the electromagnetic valve 2 (hereinafter referred to as the electromagnetic valve voltage) rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases. Along with the increase in the electromagnetic valve current, the magnetic attraction force increases, and the movable core moves between time t1 and time t2, and the electromagnetic valve 2 becomes an open valve state. When the movable core moves, as shown by the dashed circle CL1, in the time change of the electromagnetic valve current, a current singularity point occurs where the current changes from decreasing to increasing.

[0031] The timing chart TC2 of FIG. 2 shows the time changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current when the switching element 14 is switched from the off state to the on state when the electromagnetic valve 2 is stuck.

[0032] As shown in the timing chart TC2 of FIG. 2, the vehicle power supply 4 constantly outputs a power supply voltage with a voltage value VB. Then, when the switching element 14 switches from the off state to the on state at time t0, the electromagnetic valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases. However, even though the movable core moves between time t1 and time t2 during normal operation, due to sticking, the movable core does not move, so a current singularity point does not occur at time t2.

[0033] The timing chart TC3 of FIG. 2 shows the time changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current when the switching element 14 is switched from the off state to the on state when the electromagnetic valve 2 is stuck, similar to the timing chart TC2. However, the timing chart TC3 is different from the timing chart TC2 in that a rapid change in the power supply voltage occurs while the electromagnetic valve current is increasing.

[0034] As shown in the timing chart TC3 of FIG. 2, the power supply voltage rapidly decreases from VB [V] to V1 [V] at time t1. As a result, the solenoid valve voltage rapidly decreases from Vc [V] to V2 [V]. Further, the power supply voltage rapidly increases from V1 [V] to VB [V] at time t2. As a result, the solenoid valve voltage rapidly increases from V2 [V] to Vc [V]. For this reason, even though the movable core does not move due to sticking, as shown by the broken circle CL2, a current singularity occurs at time t2. That is, there is a risk that the solenoid valve 2 may be judged to be normal even though sticking has occurred in the solenoid valve 2.

[0035] Next, the procedure of the failure determination process executed by the CPU 21 of the microcomputer 19 will be described. The failure determination process is a process that is executed every time the timing to switch the solenoid valve 2 from the valve non-energized state to the valve energized state arrives.

[0036] When the failure determination process is executed, as shown in FIG. 3, the CPU 21 first switches the solenoid valve 2 from the off state to the on state at S10. Specifically, the CPU 21 switches the switching element 14 from the off state to the on state.

[0037] Then, the CPU 21 reads the power supply voltage at S20. Specifically, the CPU 21 acquires a voltage detection signal from the voltage detection circuit 17, calculates a power supply voltage value based on the acquired voltage detection signal, and further stores the calculated power supply voltage value in the RAM 23.

[0038] Furthermore, the CPU 21 reads the solenoid valve signal at S30. Specifically, the CPU 21 acquires a current detection signal from the current detection circuit 16, calculates a solenoid valve current value based on the acquired current detection signal, and further stores the calculated solenoid valve current value in the RAM 23.

[0039] Then, the CPU 21 determines whether there is a change in the power supply voltage at S40. Specifically, the CPU 21 determines whether the difference between the power supply voltage value calculated in the previous S20 and the power supply voltage value calculated in the current S20 is equal to or greater than a preset voltage change determination value.

[0040] Here, when there is a fluctuation in the power supply voltage, the CPU 21 switches the solenoid valve 2 from the on state to the off state at S50. Specifically, the CPU 21 switches the switching element 14 from the on state to the off state.

[0041] Furthermore, the CPU 21 reads the solenoid valve signal at S60 and waits until the solenoid valve current value becomes 0. Then, when the solenoid valve current value becomes 0, the CPU 21 proceeds to S10. Also at S40, when there is no fluctuation in the power supply voltage, the CPU 21 determines at S50 whether a current singularity has been detected. Specifically, the CPU 21 determines that a current singularity has been detected when the solenoid valve current value continuously decreases from before the preset first singularity determination time until the previous failure determination process, and in the current failure determination process, the solenoid valve current value changes from decreasing to increasing.

[0042] Here, when no current singularity has been detected, the CPU 21 determines at S80 whether the solenoid valve current value is saturated. Specifically, the CPU 21 calculates the difference between the solenoid valve current value calculated in the previous S30 and the solenoid valve current value calculated in the current S30 (hereinafter referred to as the solenoid valve current difference), and sequentially stores the calculated solenoid valve current values in the RAM 23. Then, based on the plurality of stored solenoid valve current values, the CPU 21 determines that the solenoid valve current value is saturated when the state where the solenoid valve current value is less than the preset saturation determination value continues for the preset saturation determination time.

[0043] Here, when the solenoid valve current value is not saturated, the CPU 21 proceeds to S20. On the other hand, when the solenoid valve current value is saturated, the CPU 21 sets the solenoid valve failure flag F1 provided in the RAM 23 at S90 and ends the failure determination process. In the following description, setting a flag means setting the value of that flag to 1, and clearing a flag means setting the value of that flag to 0.

[0044] Also, when the current singularity is detected at S70, the CPU 21 clears the solenoid valve failure flag F1 at S100 and ends the failure determination process. The timing chart TC4 in FIG. 4 shows the time changes of the power supply voltage, the solenoid valve voltage, and the solenoid valve current when a rapid change in the power supply voltage occurs during normal operation of the solenoid valve 2 of the first embodiment.

[0045] As shown in the timing chart TC4 of FIG. 4, the vehicle power supply 4 constantly outputs a power supply voltage with a voltage value VB. Then, when the switching element 14 switches from the off state to the on state at time t10, the solenoid valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the solenoid valve current gradually increases.

[0046] Then, at time t11, the power supply voltage rapidly decreases from VB [V] to V1 [V]. As a result, the solenoid valve voltage rapidly decreases from Vc [V] to V2 [V], and the solenoid valve current also decreases. When the power supply voltage rapidly decreases at time t11, when the switching element 14 switches from the on state to the off state at time t12, the solenoid valve voltage rapidly decreases from V2 [V] to 0 [V], and the solenoid valve current gradually decreases.

[0047] Then, when the solenoid valve current becomes 0, the switching element 14 switches from the off state to the on state at time t13, and the solenoid valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the solenoid valve current gradually increases. And as the solenoid valve current increases, the magnetic attraction force increases, and when the movable core moves, a current singularity occurs at time t14.

[0048] The ECU 1 configured in this way controls the solenoid valve 2 mounted on the vehicle, and includes a shunt resistor 15, a current detection circuit 16, a voltage detection circuit 17, and a microcomputer 19.

[0049] The shunt resistor 15 and the current detection circuit 16 detect the solenoid valve current flowing through the solenoid valve 2 after the power supply to the solenoid valve 2 is started. The voltage detection circuit 17 detects the power supply voltage of the vehicle power supply 4.

[0050] The microcomputer 19 detects a current singularity (hereinafter referred to as the solenoid valve current singularity) in the time change of the solenoid valve current. The microcomputer 19 detects the sticking failure of the solenoid valve 2 based on the detection result of the solenoid valve current singularity.

[0051] The microcomputer 19 determines whether a fluctuation in the power supply voltage has occurred based on the detection result by the voltage detection circuit 17. When it is determined that a fluctuation in the power supply voltage has occurred, the detection of the sticking failure is prohibited until a preset prohibition release condition is satisfied. The prohibition release condition in this embodiment is that the solenoid valve current becomes 0.

[0052] Such an ECU 1 can suppress the occurrence of a situation in which the failed solenoid valve 2 is misjudged as normal due to voltage fluctuations in the vehicle power supply 4, and can improve the detection accuracy of the solenoid valve failure.

[0053] In the embodiment described above, the ECU 1 corresponds to an electronic control unit, the shunt resistor 15 and the current detection circuit 16 correspond to a solenoid valve current detection unit, the vehicle power supply 4 corresponds to a DC power supply, and the voltage detection circuit 17 corresponds to a power supply voltage detection unit.

[0054] Also, S70 corresponds to the process as a solenoid valve current singularity detection unit, S90 and S100 correspond to the process as a solenoid valve current failure detection unit, and S40 to S60 correspond to the process as a failure detection prohibition unit.

[0055] [Second Embodiment] The second embodiment of the present disclosure will be described below with reference to the drawings. In the second embodiment, the parts different from the first embodiment will be described. The same reference numerals are given to the common configurations.

[0056] The ECU 1 of the second embodiment is different from the first embodiment in that the failure determination process is changed. Next, the procedure of the failure determination process of the second embodiment will be described. When the failure determination process of the second embodiment is executed, as shown in FIG. 5, the CPU 21 first switches the solenoid valve 2 from the off state to the on state at S210.

[0057] Then, the CPU 21 reads the power supply voltage at S220. Further, the CPU 21 reads the solenoid valve current at S230. Then, the CPU 21 determines whether there is a fluctuation in the power supply voltage at S240.

[0058] Here, if there is a fluctuation in the power supply voltage, the CPU 21 sets the voltage stability standby flag F2 and the invalid flag F3 provided in the RAM 23 at S250. Further, the CPU 21 resets (i.e., sets to 0) the standby timer provided in the RAM 23 at S260 and shifts to S220.

[0059] Also, if there is no fluctuation in the power supply voltage at S240, the CPU 21 determines whether the voltage stability standby flag F2 is set at S270. Here, if the voltage stability standby flag F2 is set, the CPU 21 increments (i.e., adds 1) the standby timer at S280.

[0060] Then, the CPU 21 determines whether a preset standby time has elapsed at S290. Specifically, the CPU 21 determines whether the value of the standby timer is equal to or greater than the standby time equivalent value corresponding to the standby time.

[0061] Here, if the standby time has not elapsed, the CPU 21 shifts to S220. On the other hand, if the standby time has elapsed, the CPU 21 clears the voltage stability standby flag F2 at S300 and shifts to S220.

[0062] Also, if the voltage stability standby flag F2 is cleared at S270, the CPU 21 determines whether a current singularity has been detected at S310. Here, if a current singularity has not been detected, the CPU 21 determines whether the solenoid valve current value is saturated at S320.

[0063] Here, when the solenoid valve current value is not saturated, the CPU 21 proceeds to S220. On the other hand, when the solenoid valve current value is saturated, the CPU 21 determines at S330 whether the invalid flag F3 is set.

[0064] Here, when the invalid flag F3 is set, the CPU 21 clears the invalid flag F3 at S340. Then the CPU 21 switches the solenoid valve 2 from the on state to the off state at S350. Further, the CPU 21 waits at S360 until the solenoid valve current value becomes 0, and when the solenoid valve current value becomes 0, it proceeds to S210.

[0065] Also at S330, when the invalid flag F3 is cleared, the CPU 21 sets the solenoid valve failure flag F1 at S370 and ends the failure determination process. Also at S310, when a current singularity is detected, the CPU 21 clears the solenoid valve failure flag F1 at S380 and ends the failure determination process.

[0066] The timing chart TC5 in FIG. 6 shows the time changes of the power supply voltage, the solenoid valve voltage, and the solenoid valve current when a rapid change in the power supply voltage occurs during normal operation of the solenoid valve 2 in the second embodiment.

[0067] As shown in the timing chart TC5 of FIG. 6, the vehicle power supply 4 constantly outputs a power supply voltage with a voltage value VB. Then, when the switching element 14 switches from the off state to the on state at time t20, the solenoid valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the solenoid valve current gradually increases.

[0068] Then, at time t21, the power supply voltage rapidly decreases from VB [V] to V1 [V]. As a result, the voltage stabilization standby flag F2 and the invalid flag F3 are set. Also, the solenoid valve voltage rapidly decreases from Vc [V] to V2 [V], and the solenoid valve current also decreases.

[0069] Furthermore, at time t22, the power supply voltage rapidly increases from V1 [V] to VB [V]. This causes the solenoid valve voltage to rapidly increase from V2 [V] to Vc [V], and a current singularity occurs. However, at time t22, the invalid flag F3 is set.

[0070] After that, the voltage stable standby flag F2 is cleared at time t23 while the solenoid valve current is gradually increasing. Then, as the solenoid valve current increases, the magnetic attraction force increases, causing the movable core to move, and a current singularity occurs at time t24. This clears the solenoid valve failure flag F1.

[0071] The ECU 1 configured in this manner controls the solenoid valve 2 mounted on a vehicle, and includes a shunt resistor 15, a current detection circuit 16, a voltage detection circuit 17, and a microcomputer 19.

[0072] The microcomputer 19 detects solenoid valve current singular points in the time change of the solenoid valve current. The microcomputer 19 detects a sticking fault of the solenoid valve 2 based on the detection result of the solenoid valve current singular point.

[0073] The microcomputer 19 judges whether or not a fluctuation in the power supply voltage VB has occurred based on the detection result by the voltage detection circuit 17, and when it judges that a fluctuation in the power supply voltage VB has occurred, it prohibits detection of a sticking fault until a preset prohibition release condition is satisfied. The prohibition release condition in this embodiment is that a preset waiting time has elapsed since the occurrence of a fluctuation in the power supply voltage VB.

[0074] Such an ECU 1 can prevent the occurrence of a situation in which a faulty solenoid valve 2 is erroneously determined to be normal due to voltage fluctuations in the vehicle power supply 4, and can improve the accuracy of detecting a solenoid valve failure.

[0075] In the embodiment described above, S310 corresponds to the process as an electromagnetic valve current singularity detection unit, S370 and S380 correspond to the process as an electromagnetic valve current fault detection unit, S240 to S300 correspond to the process as a fault detection prohibition unit, and the standby time corresponds to the prohibition time.

[0076] [Third Embodiment] The third embodiment of the present disclosure will be described below with reference to the drawings. In the third embodiment, the parts different from the first embodiment will be described. The same reference numerals are given to the common configurations.

[0077] The ECU1 of the third embodiment is different from the first embodiment in that the fault determination process is changed. Next, the procedure of the fault determination process of the third embodiment will be described. When the fault determination process of the third embodiment is executed, as shown in FIG. 7, the CPU21 first switches the electromagnetic valve 2 from the off state to the on state at S410.

[0078] Then the CPU21 reads the power supply voltage at S420. Further, the CPU21 reads the electromagnetic valve current at S430. Then the CPU21 determines at S440 whether a current singularity has been detected. Here, if a current singularity is detected, the CPU21 determines at S450 whether there is a fluctuation in the power supply voltage. Here, if there is a fluctuation in the power supply voltage, the CPU21 sets the invalid flag F3 at S460 and shifts to S420. On the other hand, if there is no fluctuation in the power supply voltage, the CPU21 clears the electromagnetic valve fault flag F1 at S470 and ends the fault determination process.

[0079] Also, if no current singularity is detected at S440, the CPU21 determines at S480 whether the electromagnetic valve current value is saturated. Here, if the electromagnetic valve current value is not saturated, the CPU21 shifts to S420. On the other hand, if the electromagnetic valve current value is saturated, the CPU21 determines at S490 whether the invalid flag F3 is set.

[0080] Here, when the invalid flag F3 is set, the CPU 21 clears the invalid flag F3 at S500. Then, the CPU 21 switches the solenoid valve 2 from the on state to the off state at S510. Further, the CPU 21 waits at S520 until the solenoid valve current value becomes 0, and when the solenoid valve current value becomes 0, it proceeds to S410.

[0081] Also, at S490, when the invalid flag F3 is cleared, the CPU 21 sets the solenoid valve failure flag F1 at S530 and ends the failure determination process. The timing chart TC6 in FIG. 8 shows the time changes of the power supply voltage, the solenoid valve voltage, and the solenoid valve current when a rapid change in the power supply voltage occurs during normal operation of the solenoid valve 2 in the third embodiment.

[0082] As shown in the timing chart TC6 of FIG. 8, the vehicle power supply 4 constantly outputs a power supply voltage with a voltage value VB. Then, when the switching element 14 switches from the off state to the on state at time t30, the solenoid valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the solenoid valve current gradually increases.

[0083] Then, at time t31, the power supply voltage rapidly decreases from VB [V] to V1 [V]. As a result, the invalid flag F3 is set. Also, the solenoid valve voltage rapidly decreases from Vc [V] to V2 [V], and the solenoid valve current also decreases.

[0084] Furthermore, at time t32, the power supply voltage rapidly increases from V1 [V] to VB [V]. As a result, the solenoid valve voltage rapidly increases from V2 [V] to Vc [V], and a current singularity occurs. However, the invalid flag F3 is set at time t32.

[0085] After that, as the solenoid valve current increases, the magnetic attraction force increases, and the movable core moves, causing a current singularity at time t33. Since the power supply voltage has not fluctuated at this point, the solenoid valve failure flag F1 is cleared.

[0086] The ECU1 configured as described above controls the solenoid valve 2 mounted on the vehicle, and includes a shunt resistor 15, a current detection circuit 16, a voltage detection circuit 17, and a microcomputer 19.

[0087] The microcomputer 19 detects a solenoid valve current singularity in the time variation of the solenoid valve current. Based on the detection result of the solenoid valve current singularity, the microcomputer 19 detects a sticking failure of the solenoid valve 2.

[0088] Based on the detection result by the voltage detection circuit 17, the microcomputer 19 determines whether a power supply voltage fluctuation has occurred. When it is determined that a power supply voltage fluctuation has occurred, at least the detection result of the solenoid valve current singularity corresponding to the time point when the power supply voltage fluctuation occurred is invalidated.

[0089] Such an ECU1 can suppress the occurrence of a situation where a failed solenoid valve 2 is misjudged as normal due to a voltage fluctuation in the vehicle power supply 4, and can improve the detection accuracy of solenoid valve failures.

[0090] In the embodiment described above, S440 corresponds to the process as a solenoid valve current singularity detection unit, S470 and S530 correspond to the processes as a solenoid valve current failure detection unit, and S450 and S460 correspond to the processes as an invalidation unit.

[0091] [Fourth Embodiment] The fourth embodiment of the present disclosure will be described below with reference to the drawings. In the fourth embodiment, the parts different from the first embodiment will be described. The same reference numerals are given to the common configurations.

[0092] The ECU1 of the fourth embodiment is different from the first embodiment in that the configuration of the ECU1 is changed and a regenerative current failure determination process is executed instead of the failure determination process. As shown in FIG. 9, the ECU 1 of the fourth embodiment differs from the first embodiment in that the voltage detection circuit 17 is omitted and the connection of the diode 13, the switching element 14, and the shunt resistor 15 is changed.

[0093] That is, for the diode 13, the anode is connected to the second end of the shunt resistor 15, and the cathode is connected to the positive terminal 11. Also, the first end of the switching element 14 is connected to the second end of the shunt resistor 15, and the second end of the switching element 14 is grounded. Further, the first end of the shunt resistor 15 is connected to the negative terminal 12.

[0094] When the switching element 14 is in the on state, current flows from the vehicle power supply 4 to the solenoid coil 3. Then, when the switching element 14 becomes off, due to the energy accumulated in the solenoid coil 3 when the switching element 14 was in the on state, current continues to flow through the diode 13 to the solenoid coil 3 (i.e., it refluxes).

[0095] The same current as the current flowing through the diode 13 flows through the shunt resistor 15. Therefore, the current detection circuit 16 detects the current (i.e., the regenerative current) flowing through the diode 13 immediately after the switching element 14 switches from the on state to the off state.

[0096] Next, the procedure of the regenerative current failure determination process of the fourth embodiment will be described. The regenerative current failure determination process is a process that is executed every time the timing to switch the solenoid valve 2 from the valve - energized state to the valve - non - energized state arrives.

[0097] When the regenerative current failure determination process is executed, as shown in FIG. 10, first, at S610, the CPU 21 switches the solenoid valve 2 from the on state to the off state. Further, at S620, the CPU 21 reads the regenerative current. Specifically, the CPU 21 acquires a current detection signal from the current detection circuit 16, calculates a regenerative current value based on the acquired current detection signal, and further stores the calculated regenerative current value in the RAM 23.

[0098] Then, at S630, the CPU 21 determines whether a current singularity has been detected. Specifically, the CPU 21 determines that a current singularity has been detected when the regenerative current value has continuously increased from before a preset second singularity determination time until the previous regenerative current fault determination process, and in the current regenerative current fault determination process, the regenerative current value has changed from increasing to decreasing.

[0099] Here, when a current singularity is detected, the CPU 21 clears the solenoid valve fault flag F1 at S640 and ends the regenerative current fault determination process. On the other hand, when a current singularity has not been detected, the CPU 21 determines at S650 whether the regenerative current value has reached 0. Here, when the regenerative current value has not reached 0, the CPU 21 proceeds to S620. On the other hand, when the regenerative current value has reached 0, the CPU 21 sets the solenoid valve fault flag F1 at S640 and ends the regenerative current fault determination process.

[0100] Timing chart TC7 in FIG. 11 shows the time changes of the power supply voltage, the solenoid valve voltage, and the solenoid valve current when a rapid change in the power supply voltage occurs during normal operation of the solenoid valve 2 in the fourth embodiment.

[0101] As shown in the timing chart TC7 of FIG. 11, the vehicle power supply 4 constantly outputs a power supply voltage with a voltage value VB. Then, when the switching element 14 switches from the on state to the off state at time t40, the solenoid valve voltage rapidly decreases from Vc [V] to 0 [V] or less. As a result, the solenoid valve current gradually decreases.

[0102] Then, at time t41, the power supply voltage rapidly decreases from VB [V] to V1 [V]. The solenoid valve current is not affected by this rapid decrease in the power supply voltage. Furthermore, at time t42, the power supply voltage rapidly increases from V1 [V] to VB [V]. The solenoid valve current is not affected by this rapid increase in the power supply voltage.

[0103] Then, as the magnetic attraction force decreases with the decrease in the solenoid valve current, the movable core moves, and the solenoid valve 2 enters the closed state. Note that when the movable core moves, a current singularity that changes from increasing to decreasing occurs at time t43.

[0104] FIG. 12 is a diagram showing the configuration of the ECU 1 to which a Zener diode 31 is connected to clamp the surge generated when the solenoid valve 2 is turned off. In the ECU 1 shown in FIG. 12, the anode of the Zener diode 31 is grounded, and the cathode of the Zener diode 31 is connected to the connection point between the switching element 14 and the shunt resistor 15. Also, the diode 13 is omitted.

[0105] The timing chart TC8 in FIG. 13 shows the time changes of the voltage at the negative terminal 12 (hereinafter referred to as the negative terminal voltage) and the solenoid valve current when the solenoid valve 2 is switched from the on state to the off state. The line L1 in the timing chart TC8 shows the time change of the negative terminal voltage in the ECU 1 of the fourth embodiment. The line L2 shows the time change of the negative terminal voltage in the ECU 1 shown in FIG. 12. The line L3 shows the time change of the solenoid valve current in the ECU 1 of the fourth embodiment. The line L4 shows the time change of the solenoid valve current in the ECU 1 shown in FIG. 12.

[0106] As shown in FIG. 12, when the switching element 14 switches from the on state to the off state at time t50, the negative terminal voltage rapidly increases and the solenoid valve current gradually decreases. Note that the negative terminal voltage of the ECU 1 shown in FIG. 12 is higher than that of the ECU 1 of the fourth embodiment. Also, the solenoid valve current of the ECU 1 shown in FIG. 12 decreases faster than that of the ECU 1 of the fourth embodiment.

[0107] Then, when the movable core moves between time t51 and time t52, a current singularity occurs in the ECU 1 of the fourth embodiment. However, in the ECU 1 shown in FIG. 12, the solenoid valve current has flowed out before the movable core moves, and no current singularity occurs. Therefore, in order to generate a current singularity, it is desirable not to use the Zener diode 31.

[0108] The timing chart TC9 in FIG. 14 shows the time variation of the solenoid valve current when the solenoid valve 2 is switched from the on state to the off state. The line L11 of the timing chart TC9 shows the time variation of the solenoid valve current when the diode 13 is a rectifier diode. The line L12 of the timing chart TC9 shows the time variation of the solenoid valve current when the diode 13 is a Schottky barrier diode. The rectifier diode has a larger forward voltage Vf than the Schottky barrier diode. In the present embodiment, the forward voltage Vf of the rectifier diode is 0.7V, and the forward voltage Vf of the Schottky barrier diode is 0.4V.

[0109] As shown in FIG. 14, when the switching element 14 is switched from the on state to the off state at time t60, the solenoid valve current gradually decreases. However, when the diode 13 is a rectifier diode, the solenoid valve current decreases faster than when the diode 13 is a Schottky barrier diode.

[0110] Then, when the diode 13 is a rectifier diode, the movable core moves between time t61 and time t62. Also, when the diode 13 is a Schottky barrier diode, the movable core moves between time t63 and time t64. As shown in FIG. 14, by using a Schottky barrier diode for the diode 13, the rise of the solenoid valve current during the valve operation can be increased, and the current singularity can be significantly generated.

[0111] The ECU1 configured in this way controls the solenoid valve 2 mounted on the vehicle, and includes a shunt resistor 15, a current detection circuit 16, and a microcomputer 19. The shunt resistor 15 and the current detection circuit 16 detect the regenerative current that flows back to the solenoid valve 2 immediately after the power supply to the solenoid valve 2 is stopped.

[0112] The microcomputer 19 detects a current singularity (hereinafter referred to as a regenerative current singularity) in the time change of the regenerative current. Then, based on the detection result of the regenerative current singularity, the microcomputer 19 detects a sticking failure of the solenoid valve 2.

[0113] Such an ECU1 detects a regenerative current singularity of the regenerative current that is not affected by the voltage fluctuation in the vehicle power supply 4. For this reason, the ECU1 can suppress the occurrence of a situation where the failed solenoid valve 2 is misjudged as normal due to the voltage fluctuation in the vehicle power supply 4, and can improve the detection accuracy of the solenoid valve failure.

[0114] Also, the ECU1 includes a diode 13 through which the regenerative current flows. Thereby, the ECU1 can gradually decrease the regenerative current and can easily generate a regenerative current singularity in the time change of the regenerative current.

[0115] In the embodiment described above, the shunt resistor 15 and the current detection circuit 16 correspond to the regenerative current detection unit, S630 corresponds to the process as the regenerative current singularity detection unit, S640 and S660 correspond to the process as the regenerative current failure detection unit, and the diode 13 corresponds to the freewheeling diode.

[0116] [Fifth Embodiment] The fifth embodiment of the present disclosure will be described below with reference to the drawings. In the fifth embodiment, the parts different from the fourth embodiment will be described. The same reference numerals are given to the common configurations.

[0117] The ECU1 of the fifth embodiment is different from the fourth embodiment in that the configuration of the ECU1 is changed and that failure determination processing is executed instead of the regenerative current failure determination processing. The ECU1 of the fifth embodiment is different from the fourth embodiment in that, as shown in FIG. 15, a voltage detection circuit 17 is added. The voltage detection circuit 17 detects the voltage at the positive terminal 11 and outputs a voltage detection signal indicating the detection result to the microcomputer 19.

[0118] Next, the procedure of the failure determination process according to the fifth embodiment will be described. The failure determination process is a process that is executed every time the timing to switch the solenoid valve 2 from the valve non-energized state to the valve energized state arrives.

[0119] As shown in FIG. 16, the failure determination process according to the fifth embodiment differs from the third embodiment in that the processes of S510 and S520 are omitted and the process of S525 is added. That is, when the process of S500 ends, the CPU 21 executes the regenerative current failure determination process according to the fourth embodiment in S525 and ends the failure determination process.

[0120] The ECU 1 configured as described above controls the solenoid valve 2 mounted on the vehicle and includes a shunt resistor 15, a current detection circuit 16, a voltage detection circuit 17, and a microcomputer 19.

[0121] The shunt resistor 15 and the current detection circuit 16 detect the solenoid valve current flowing through the solenoid valve 2 after the power supply to the solenoid valve 2 is started. The voltage detection circuit 17 detects the power supply voltage of the vehicle power supply 4.

[0122] The microcomputer 19 detects a solenoid valve current singularity in the time change of the solenoid valve current. The microcomputer 19 detects a sticking failure of the solenoid valve 2 based on the detection result of the solenoid valve current singularity.

[0123] The microcomputer 19 determines whether or not a power supply voltage fluctuation has occurred based on the detection result by the voltage detection circuit 17. When it is determined that a power supply voltage fluctuation has occurred, at least the detection result of the solenoid valve current singularity corresponding to the time point when the power supply voltage fluctuation has occurred is invalidated.

[0124] The shunt resistor 15 and the current detection circuit 16 detect the regenerative current that flows back to the solenoid valve 2 immediately after the power supply to the solenoid valve 2 is stopped. The microcomputer 19 detects a regenerative current singularity in the time variation of the regenerative current. Then, based on the detection result of the regenerative current singularity, the microcomputer 19 detects a sticking failure of the solenoid valve 2.

[0125] When such a voltage fluctuation occurs in the power supply voltage, such an ECU1 invalidates the detection result of the solenoid valve current singularity and detects a regenerative current singularity of the regenerative current that is not affected by the voltage fluctuation in the vehicle power supply 4. For this reason, the ECU1 can suppress the occurrence of a situation in which the failed solenoid valve 2 is misjudged as normal due to the voltage fluctuation in the vehicle power supply 4, and can improve the detection accuracy of the solenoid valve failure.

[0126] In the embodiment described above, S440 corresponds to the process as the solenoid valve current singularity detection unit, S470 and S530 correspond to the process as the solenoid valve current failure detection unit, and S450 and S460 correspond to the process as the invalidation unit.

[0127] Also, S525 corresponds to the processes as the regenerative current singularity detection unit and the regenerative current failure detection unit. [Sixth Embodiment] The sixth embodiment of the present disclosure will be described below with reference to the drawings. In the sixth embodiment, the parts different from the fourth embodiment will be described. The same reference numerals are given to the common configurations.

[0128] The ECU1 of the sixth embodiment is different from the fourth embodiment in that the configuration of the ECU1 is changed. As shown in FIG. 17, the ECU1 of the sixth embodiment is different from the fourth embodiment in that the connection of the diode 13, the switching element 14, and the shunt resistor 15 is changed.

[0129] That is, the anode of the diode 13 is connected to the negative terminal 12, and the cathode is connected to the second end of the shunt resistor 15. Also, the first end of the switching element 14 is connected to the negative terminal 12, and the second end of the switching element 14 is grounded. Also, the first end of the shunt resistor 15 is connected to the positive terminal 11.

[0130] In the ECU1 configured in this way, the shunt resistor 15 and the current detection circuit 16 detect the regenerative current flowing in the energization path between the vehicle power supply 4 that supplies the power supply voltage to the solenoid valve 2 and the diode 13.

[0131] Similar to the ECU1 of the fourth embodiment, such an ECU1 can suppress the occurrence of a situation in which a failed solenoid valve 2 is erroneously determined to be normal due to voltage fluctuations in the vehicle power supply 4, and can improve the detection accuracy of solenoid valve failures.

[0132] [Seventh Embodiment] The seventh embodiment of the present disclosure will be described below with reference to the drawings. In the seventh embodiment, the parts different from the sixth embodiment will be described. The same reference numerals will be given to the common configurations.

[0133] As shown in FIG. 18, the ECU1 of the seventh embodiment controls the solenoid valves 2a, 2b, and 2c. The solenoid valves 2a, 2b, and 2c are each the same as the solenoid valve 2 and include solenoid coils 3a, 3b, and 3c and a movable core (not shown). The first ends of the solenoid coils 3a, 3b, and 3c are connected to the positive electrode of the vehicle power supply 4, and the second ends of the solenoid coils 3a, 3b, and 3c are grounded.

[0134] The ECU1 includes a positive terminal 11, negative terminals 12a, 12b, and 12c, diodes 13a, 13b, and 13c, switching elements 14a, 14b, and 14c, a shunt resistor 15, a current detection circuit 16, drive circuits 18a, 18b, and 18c, and a microcomputer 19.

[0135] The positive terminal 11 is connected to the first ends of the solenoid coils 3a, 3b, and 3c. The negative terminals 12a, 12b, and 12c are each connected to the second ends of the solenoid coils 3a, 3b, and 3c.

[0136] Diodes 13a, 13b, and 13c are each identical to diode 13, with their anodes connected to negative terminals 12a, 12b, and 12c, and their cathodes connected to the second end of shunt resistor 15.

[0137] Switching elements 14a, 14b, and 14c are each identical to switching element 14 and are transistors provided on the current path from solenoid coils 3a, 3b, and 3c to ground.

[0138] The first ends of switching elements 14a, 14b, and 14c are each connected to negative terminals 12a, 12b, and 12c. The second ends of switching elements 14a, 14b, and 14c are grounded. The first end of shunt resistor 15 is connected to positive terminal 11.

[0139] Drive circuits 18a, 18b, and 18c each output a drive signal to switching elements 14a, 14b, and 14c based on a control signal output from microcomputer 19 to drive switching elements 14a, 14b, and 14c so that they are in the on state or the off state.

[0140] Timing chart TC10 in FIG. 19 shows the time change of the voltage across solenoid coils 3a, 3b, and 3c when solenoid valves 2a, 2b, and 2c are switched from the on state to the off state. Hereinafter, the voltage across solenoid coils 3a, 3b, and 3c will be referred to as the first, second, and third solenoid valve voltages, respectively.

[0141] As shown in FIG. 19, when switching element 14a switches from the on state to the off state at time t70, the first solenoid valve voltage rapidly decreases from Vc [V] to 0 [V] or less. As a result, the current detected by current detection circuit 16 (hereinafter referred to as the detected current) gradually decreases, and a current singularity occurs at time t71.

[0142] Also, when the switching element 14b switches from the on state to the off state at time t72, the second solenoid valve voltage rapidly decreases from Vc [V] to 0 [V] or less. As a result, the detected current gradually decreases, and a current singularity occurs at time t73.

[0143] Also, when the switching element 14c switches from the on state to the off state at time t74, the third solenoid valve voltage rapidly decreases from Vc [V] to 0 [V] or less. As a result, the detected current gradually decreases, and a current singularity occurs at time t75.

[0144] In the ECU1 configured as described above, the shunt resistor 15 and the current detection circuit 16 detect the respective regeneration currents of the plurality of solenoid valves 2a, 2b, 2c. Since such an ECU1 does not include three current detection circuits 16 corresponding to each of the solenoid valves 2a, 2b, 2c, the configuration of the ECU1 can be simplified.

[0145] [Eighth Embodiment] The eighth embodiment of the present disclosure will be described below with reference to the drawings. In the eighth embodiment, the parts different from the fourth embodiment will be described. The same reference numerals are given to the common configurations.

[0146] The ECU1 of the eighth embodiment is different from the fourth embodiment in that, as shown in FIG. 20, a terminal state detection circuit 50 is added and a terminal failure detection process is executed. The terminal state detection circuit 50 includes resistors 51, 52 and a diode 53. The first end of the resistor 51 is connected to the internal power supply 6. The first end of the resistor 52 is connected to the microcomputer 19. The second ends of the resistors 51, 52 are connected to the anode of the diode 53. The cathode of the diode 53 is connected to the second end of the shunt resistor 15.

[0147] In the terminal state detection circuit 50 configured as described above, when the voltage level of the negative terminal 12 is at a low level, the voltage level at the connection terminal with the microcomputer 19 (i.e., the first end of the resistor 52) becomes a low level. Also, when the voltage level of the negative terminal 12 is at a high level, the voltage level at the connection terminal with the microcomputer 19 becomes a high level.

[0148] That is, when the voltage level of the negative terminal 12 is at a low level, the terminal state detection circuit 50 outputs a terminal state detection signal with a low voltage level to the microcomputer 19. Also, when the voltage level of the negative terminal 12 is at a high level, the terminal state detection circuit 50 outputs a terminal state detection signal with a high voltage level to the microcomputer 19.

[0149] As shown in the first row C1 of FIG. 21, when the ECU 1 and the solenoid valve 2 are normal and the switching element 14 is turned off, the solenoid valve 2 is turned off. Then, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes a high level. For this reason, the current detection circuit 16 outputs a current detection signal with a low voltage level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal with a high voltage level.

[0150] Also, as shown in the second row C2, when the ECU 1 and the solenoid valve 2 are normal and the switching element 14 is turned on, the solenoid valve 2 is turned on. Then, current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes a low level. For this reason, the current detection circuit 16 outputs a current detection signal with a high voltage level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal with a low voltage level.

[0151] Also, as shown in the third row C3 and the fourth row C4, in a state where a battery short circuit fault occurs in which the negative terminal 12 and the vehicle power supply 4 are short-circuited, regardless of whether the switching element 14 is in an off state or an on state, the solenoid valve 2 is turned off.

[0152] Then, as shown in the third row C3, when the switching element 14 is in the OFF state, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes high level. Therefore, the current detection circuit 16 outputs a current detection signal whose voltage level becomes low level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal whose voltage level becomes high level.

[0153] Also, in a state where a battery short circuit fault occurs in which the negative terminal 12 and the vehicle power supply 4 are short-circuited, when the switching element 14 is turned on, current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes low level. Therefore, the current detection circuit 16 outputs a current detection signal whose voltage level becomes high level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal whose voltage level becomes low level.

[0154] When an overcurrent flows through the shunt resistor 15, the switching element 14 is turned off by the IPD built in the drive circuit 18. As a result, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes high level. Therefore, the current detection circuit 16 outputs a current detection signal whose voltage level becomes low level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal whose voltage level becomes high level. IPD is an abbreviation for Intelligent Power Device.

[0155] Thereafter, when the overcurrent in the shunt resistor 15 is eliminated, the switching element 14 becomes ON again. Then, when an overcurrent flows through the shunt resistor 15 again, the switching element 14 is turned off by the IPD built in the drive circuit 18.

[0156] Therefore, as shown in the fourth row C4, when the switching element 14 is turned on in a state where a battery short circuit failure has occurred, the state where the current detection signal is at a low level and the terminal state detection signal is at a high level, and the state where the current detection signal is at a high level and the terminal state detection signal is at a low level will be alternately repeated.

[0157] Also, as shown in the fifth row C5 and the sixth row C6, in a state where a ground short circuit failure occurs in which the negative terminal 12 and the ground are short-circuited, the solenoid valve 2 is turned on regardless of whether the switching element 14 is in an off state or an on state. And regardless of whether the switching element 14 is in an off state or an on state, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes a low level. For this reason, the current detection circuit 16 outputs a current detection signal whose voltage level becomes a low level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal whose voltage level becomes a low level.

[0158] Also, as shown in the seventh row C7 and the eighth row C8, in a state where an open failure occurs in which the negative terminal 12 is open, the solenoid valve 2 is turned off regardless of whether the switching element 14 is in an off state or an on state.

[0159] And, as shown in the seventh row C7, when the switching element 14 is in an off state, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes a high level. For this reason, the current detection circuit 16 outputs a current detection signal whose voltage level becomes a low level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal whose voltage level becomes a high level.

[0160] Also, as shown in the eighth row C8, when the switching element 14 is in an on state, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 becomes a low level. For this reason, the current detection circuit 16 outputs a current detection signal whose voltage level becomes a low level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal whose voltage level becomes a low level.

[0161] Next, the procedure of the terminal fault detection process executed by the CPU 21 of the microcomputer 19 will be described. The terminal fault detection process is a process that is repeatedly executed during the operation of the microcomputer 19.

[0162] When the terminal fault detection process is executed, as shown in FIG. 22, first, at S610, the CPU 21 determines whether the switching element 14 is in the off state. Here, when the switching element 14 is not in the off state, the process of S610 is repeated to wait until the switching element 14 becomes in the off state.

[0163] Then, when the switching element 14 becomes in the off state, the CPU 21 performs a ground short fault detection at S620. Specifically, the CPU 21 determines whether the voltage level of the negative terminal 12 is at a low level based on the terminal state detection signal. Here, when the voltage level of the negative terminal 12 is at a low level, the CPU 21 sets the ground short fault flag F11 provided in the RAM 23. On the other hand, when the voltage level of the negative terminal 12 is at a high level, the CPU 21 clears the ground short fault flag F11.

[0164] When the process of S620 ends, the CPU 21 determines whether the switching element 14 is in the on state at S630. Here, when the switching element 14 is not in the on state, the process of S630 is repeated to wait until the switching element 14 becomes in the on state.

[0165] When the switching element 14 is turned on, the CPU 21 performs battery short circuit failure detection at S640. Specifically, the CPU 21 determines whether the voltage level of the negative terminal 12 repeatedly switches between the high level and the low level based on the terminal state detection signal. Here, when the voltage level of the negative terminal 12 repeatedly switches between the high level and the low level, the CPU 21 sets the battery short circuit failure flag F12 provided in the RAM 23. On the other hand, when the voltage level of the negative terminal 12 does not repeatedly switch between the high level and the low level, the CPU 21 clears the battery short circuit failure flag F12.

[0166] When the process of S640 ends, the CPU 21 performs open circuit failure detection at S650 and ends the terminal failure detection process. Specifically, the CPU 21 determines whether current is flowing through the shunt resistor 15 based on the current detection signal. Here, when no current is flowing through the shunt resistor 15, the CPU 21 sets the open circuit failure flag F13 provided in the RAM 23. On the other hand, when current is flowing through the shunt resistor 15, the CPU 21 clears the open circuit failure flag F13.

[0167] The ECU 1 configured in this way includes a positive terminal 11, a negative terminal 12, and a terminal state detection circuit 50. The positive terminal 11 is connected to the first end, which is the end on the side connected to the vehicle power supply 4 that supplies the power supply voltage VB to the solenoid valve 2 in the solenoid valve 2. The negative terminal 12 is connected to the second end, which is the end on the side connected to the ground in the solenoid valve 2.

[0168] The terminal state detection circuit 50 includes a resistor 51 and a diode 53, and detects the voltage level at the negative terminal 12. The shunt resistor 15 and the current detection circuit 16 detect the regenerative current flowing through the energization path between the negative terminal 12 and the diode 13.

[0169] When the microcomputer 19 stops supplying the power voltage to the solenoid valve 2, it detects a ground short circuit fault at the negative terminal 12 based on the detection result of the terminal state detection circuit 50.

[0170] When the microcomputer 19 supplies the power voltage to the solenoid valve 2, it detects a battery short circuit fault at the negative terminal 12 based on the detection result of the terminal state detection circuit 50.

[0171] When the microcomputer 19 supplies the power to the solenoid valve 2, it detects an open fault at the negative terminal 12 based on the detection result of the terminal state detection circuit 50. Such an ECU 1 can detect a ground short circuit fault, a battery short circuit fault, and an open fault at the negative terminal 12.

[0172] In the embodiment described above, the terminal state detection circuit 50 corresponds to a terminal state detection unit, the resistor 51 corresponds to a pull-up resistor, S620 corresponds to the process as a ground short circuit fault detection unit, S640 corresponds to the process as a battery short circuit fault detection unit, and S650 corresponds to the process as a first open fault detection unit.

[0173] [Embodiment 9] The ninth embodiment of the present disclosure will be described below with reference to the drawings. In the ninth embodiment, the differences from the sixth embodiment will be described. The same reference numerals are assigned to the common configurations.

[0174] As shown in FIG. 23, the ECU 1 of the ninth embodiment is different from the sixth embodiment in that the terminal state detection circuit 50 is added and the terminal fault detection process is executed. Since the terminal state detection circuit 50 of the ninth embodiment is the same as that of the eighth embodiment, the description thereof is omitted.

[0175] As shown in FIGS. 21 and 24, the first row C1 and the second row C2 in FIG. 24 are the same as the first row C1 and the second row C2 in FIG. 21, respectively. Also, the fourth row C4 and the fifth row C5 in FIG. 24 are the same as the third row C3 and the fourth row C4 in FIG. 21, respectively. Also, the seventh row C7 and the eighth row C8 in FIG. 24 are the same as the fifth row C5 and the sixth row C6 in FIG. 21, respectively. Also, the tenth row C10 and the eleventh row C11 in FIG. 24 are the same as the seventh row C7 and the eighth row C8 in FIG. 21, respectively. For this reason, the descriptions of the first row C1, the second row C2, the fourth row C4, the fifth row C5, the seventh row C7, the eighth row C8, the tenth row C10, and the eleventh row C11 in FIG. 24 are omitted.

[0176] As shown in the third row C3 of FIG. 24, when the switching element 14 is switched from the on state to the off state when the ECU1 and the solenoid valve 2 are normal, the solenoid valve 2 is switched from the on state to the off state. As a result, current flows through the shunt resistor 15 only for a short time, and the voltage level of the negative terminal 12 changes from the low level to the high level. For this reason, the current detection signal output from the current detection circuit 16 becomes high level only for a short time from the low level and then returns to the low level again. Also, the terminal state detection signal output from the terminal state detection circuit 50 changes from the low level to the high level.

[0177] As shown in the sixth row C6 of FIG. 24, when the switching element 14 is switched from the on state to the off state in a state where a battery short circuit failure has occurred, the solenoid valve 2 remains in the off state. At this time, as in the normal state, current flows through the shunt resistor 15 only for a short time, and the voltage level of the negative terminal 12 changes from the low level to the high level. For this reason, the current detection signal output from the current detection circuit 16 becomes high level only for a short time from the low level and then returns to the low level again. Also, the terminal state detection signal output from the terminal state detection circuit 50 changes from the low level to the high level.

[0178] As shown in the 9th row C9 of FIG. 24, when the switching element 14 is switched from the on state to the off state in a state where a ground short circuit fault has occurred, the solenoid valve 2 remains in the on state. At this time, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 remains at the low level. Therefore, the current detection circuit 16 outputs a current detection signal whose voltage level becomes the low level. Also, the terminal state detection circuit 50 outputs a terminal state detection signal whose voltage level becomes the low level.

[0179] As shown in the 12th row C12 of FIG. 24, when the switching element 14 is switched from the on state to the off state in a state where an open fault has occurred, the solenoid valve 2 remains in the off state. At this time, no current flows through the shunt resistor 15, and the voltage level of the negative terminal 12 changes from the low level to the high level. Therefore, the current detection signal output from the current detection circuit 16 remains at the low level. Also, the terminal state detection signal output from the terminal state detection circuit 50 changes from the low level to the high level.

[0180] Next, the procedure of the terminal fault detection process executed by the CPU 21 of the microcomputer 19 will be described. As shown in FIG. 25, the terminal fault detection process of the 9th embodiment is different from the terminal fault detection process of the 8th embodiment in that the process of S650 is omitted and the processes of S660 and S670 are added.

[0181] That is, when the process of S640 ends, the CPU 21 determines in S660 whether the switching element 14 is in the off state. Here, if the switching element 14 is not in the off state, the process of S660 is repeated to wait until the switching element 14 becomes in the off state.

[0182] When the switching element 14 is turned off, the CPU 21 performs open fault detection at S670 and ends the terminal fault detection process. Specifically, the CPU 21 determines whether current flows through the shunt resistor 15 based on the current detection signal. Here, when no current flows through the shunt resistor 15, the CPU 21 sets the open fault flag F13. On the other hand, when current flows through the shunt resistor 15, the CPU 21 clears the open fault flag F13.

[0183] The thus configured ECU 1 includes a positive terminal 11, a negative terminal 12, and a terminal state detection circuit 50. Based on the detection result of the terminal state detection circuit 50 when the power supply voltage to the solenoid valve 2 is stopped, the microcomputer 19 detects a ground short fault at the negative terminal 12.

[0184] Based on the detection result of the terminal state detection circuit 50 when the power supply voltage is supplied to the solenoid valve 2, the microcomputer 19 detects a battery short fault at the negative terminal 12.

[0185] Based on the detection result of the terminal state detection circuit 50 immediately after the supply of the power supply voltage to the solenoid valve 2 is stopped, the microcomputer 19 detects an open fault at the negative terminal 12.

[0186] Such an ECU 1 can detect a ground short fault, a battery short fault, and an open fault at the negative terminal 12. In the embodiment described above, S670 corresponds to the process as the second open fault detection unit.

[0187] Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment and can be implemented in various modifications. [Modification Example 1] For example, in the above embodiment, a form was shown in which a point where the solenoid valve current value changes from decreasing to increasing in the time change of the solenoid valve current is detected as a solenoid valve current singularity. However, the solenoid valve current singularity only needs to be a point that can identify the transition between the closed valve state and the open valve state of the solenoid valve 2. For example, it may be a point where the solenoid valve current value changes from increasing to decreasing, or it may be a point where the decreasing slope changes rapidly.

[0188] [Modification Example 2] In the above embodiment, a form was shown in which a point where the regenerative current value changes from increasing to decreasing in the time change of the regenerative current is detected as a regenerative current singularity. However, the regenerative current singularity only needs to be a point that can identify the transition between the closed valve state and the open valve state of the solenoid valve 2. For example, it may be a point where the regenerative current value changes from decreasing to increasing, or it may be a point where the increasing slope changes rapidly.

[0189] The microcomputer 19 and its method described in the present disclosure may be realized by a dedicated computer configured by a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the microcomputer 19 and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Or, the microcomputer 19 and its method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer. The method for realizing the functions of each part included in the microcomputer 19 does not necessarily need to include software, and all of its functions may be realized using one or more hardware.

[0190] The multiple functions of one component in the above embodiment may be realized by a plurality of components, or one function of one component may be realized by a plurality of components. Further, the multiple functions of a plurality of components may be realized by one component, or one function realized by a plurality of components may be realized by one component. Also, a part of the configuration of the above embodiment may be omitted. Further, at least a part of the configuration of the above embodiment may be added to or replaced with the configuration of another above embodiment.

[0191] In addition to the above-described ECU 1, the present disclosure can also be realized in various forms such as a system including the ECU 1 as a component, a program for causing a computer to function as the ECU 1, a non-transitory tangible recording medium such as a semiconductor memory storing this program, and a failure detection method.

Description of Reference Numerals

[0192] 1... ECU, 2... solenoid valve, 4... vehicle power supply, 15... shunt resistor, 16... current detection circuit, 17... voltage detection circuit, 19... microcomputer

Claims

1. An electronic control unit (1) for controlling at least one solenoid valve (2) mounted on a vehicle, a regenerative current detection unit (15, 16) configured to detect a regenerative current flowing back to the at least one solenoid valve immediately after the power supply to the at least one solenoid valve is stopped; a regenerative current singularity detection unit (S630) configured to detect a regenerative current singularity that is a singularity in the time change of the regenerative current; a regenerative current fault detection unit (S640, S660) configured to detect a sticking fault of the at least one solenoid valve based on a detection result by the regenerative current singularity detection unit An electronic control unit comprising.

2. The electronic control unit according to claim 1, An electronic control unit comprising a freewheeling diode (13) through which the regenerative current flows.

3. The electronic control unit according to claim 2, The regenerative current detection unit is an electronic control unit that detects the regenerative current flowing in a current conduction path between a DC power supply (4) that supplies a power supply voltage to the at least one solenoid valve and the freewheeling diode.

4. The electronic control unit according to any one of claims 1 to 3, The at least one solenoid valve is a plurality of solenoid valves, An electronic control unit in which one regenerative current detection unit detects the regenerative current of each of the plurality of solenoid valves.

5. The electronic control unit according to claim 2, In the at least one solenoid valve, with the end on the side connected to the DC power supply that supplies the power supply voltage to the at least one solenoid valve as the first end and the end on the side connected to the ground as the second end, the electronic control unit further includes: a positive terminal (11) connected to the first end; a negative terminal (12) connected to the second end; a terminal state detection unit (50) including a pull-up resistor (51) and a diode (53) and configured to detect a voltage level at the negative terminal; The regenerative current detection unit detects the regenerative current flowing in a current conduction path between the negative terminal and the freewheeling diode, The electronic control unit further includes: a ground short fault detection unit (S620) configured to detect a ground short fault at the negative terminal based on a detection result of the terminal state detection unit when the supply of the power supply voltage to the at least one solenoid valve is stopped; A battery short circuit fault detection unit (S640) configured to detect a battery short circuit fault at the negative terminal based on a detection result of the terminal state detection unit when the power supply voltage is being supplied to the at least one solenoid valve. A first open fault detection unit (S650) configured to detect an open fault at the negative terminal based on a detection result of the regenerative current detection unit when the power supply is being supplied to the at least one solenoid valve. An electronic control device comprising the same.

6. The electronic control device according to claim 3, In the at least one solenoid valve, with an end on the side connected to a DC power supply that supplies the power supply voltage to the at least one solenoid valve as a first end and an end on the side connected to ground as a second end, the electronic control device further includes: A positive terminal connected to the first end; A negative terminal connected to the second end; A terminal state detection unit configured to include a pull-up resistor and a diode and detect a voltage level at the negative terminal; A ground short circuit fault detection unit configured to detect a ground short circuit fault at the negative terminal based on a detection result of the terminal state detection unit when the supply of the power supply voltage to the at least one solenoid valve is stopped; A battery short circuit fault detection unit configured to detect a battery short circuit fault at the negative terminal based on a detection result of the terminal state detection unit when the power supply voltage is being supplied to the at least one solenoid valve; A second open fault detection unit (S670) configured to detect an open fault at the negative terminal based on a detection result of the regenerative current detection unit immediately after the supply of the power supply voltage to the at least one solenoid valve is stopped. An electronic control device comprising the same.

7. An electronic control device (1) for controlling at least one solenoid valve (2) mounted on a vehicle, A solenoid valve current detection unit (15, 16) configured to detect a solenoid valve current flowing through the at least one solenoid valve after the start of the power supply to the at least one solenoid valve; A power supply voltage detection unit (17) configured to detect the power supply voltage of a DC power supply (4) that supplies the power supply voltage to the at least one solenoid valve. A solenoid valve current singularity detection unit (S70, S310) configured to detect a solenoid valve current singularity that is a singularity in the time change of the solenoid valve current; A solenoid valve current fault detection unit (S90, S100, S370, S380) configured to detect a sticking fault of the at least one solenoid based on a detection result by the solenoid valve current singularity detection unit; Based on the detection result by the power supply voltage detection unit, it is determined whether or not a fluctuation in the power supply voltage has occurred. When it is determined that a fluctuation in the power supply voltage has occurred, until a preset prohibition release condition is satisfied, a fault detection prohibition unit (S40 to S60, S240 to S300) configured to prohibit the detection of the sticking fault by the solenoid valve current fault detection unit; Comprising, further, A regenerative current detection unit configured to detect a regenerative current that flows back to the at least one solenoid immediately after the power supply to the at least one solenoid is stopped; A regenerative current singularity detection unit configured to detect a regenerative current singularity that is a singularity in the time change of the regenerative current; A regenerative current fault detection unit configured to detect the sticking fault of the at least one solenoid based on a detection result by the regenerative current singularity detection unit; An electronic control device comprising.

8. The electronic control device according to claim 7, The prohibition release condition includes that the solenoid valve current becomes zero. An electronic control device.

9. The electronic control device according to claim 7, The prohibition release condition includes that a preset prohibition time has elapsed since the occurrence of the fluctuation in the power supply voltage. An electronic control device.

10. An electronic control device (1) for controlling at least one solenoid valve (2) mounted on a vehicle, A solenoid valve current detection unit (15, 16) configured to detect a solenoid valve current flowing through the at least one solenoid after the power supply to the at least one solenoid is started; A power supply voltage detection unit (17) configured to detect the power supply voltage of a DC power supply (4) that supplies the power supply voltage to the at least one solenoid; A solenoid valve current singularity detection unit (S440) configured to detect a solenoid valve current singularity that is a singularity in the time change of the solenoid valve current; A solenoid valve current fault detection unit (S470, S530) configured to detect a sticking fault of the at least one solenoid based on a detection result by the solenoid valve current singularity detection unit; Based on the detection result by the power supply voltage detection unit, it is determined whether a fluctuation in the power supply voltage has occurred. When it is determined that a fluctuation in the power supply voltage has occurred, at least an invalidation unit (S450, S460) configured to invalidate the detection result of the solenoid valve current singularity detection unit corresponding to the time point when the fluctuation in the power supply voltage has occurred is provided, and further, a regenerative current detection unit configured to detect a regenerative current that flows back to the at least one solenoid immediately after the power supply to the at least one solenoid is stopped; a regenerative current singularity detection unit configured to detect a regenerative current singularity that is a singularity in the time change of the regenerative current; a regenerative current fault detection unit configured to detect the sticking fault of the at least one solenoid based on the detection result by the regenerative current singularity detection unit is provided in the electronic control device.

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