ELECTRONIC CONTROL DEVICE

An electronic control device is configured to control at least one electromagnetic valve mounted on a vehicle. The electronic control device includes a regenerative current detector configured to detect a regenerative current circulating through the at least one electromagnetic valve immediately after power supply to the at least one electromagnetic valve is stopped. The electronic control device further includes a regenerative current singularity detector configured to detect a regenerative current singularity that is a singularity in a temporal change of the regenerative current. The electronic control device further includes a regenerative current failure detector configured to detect a stuck failure of the at least one electromagnetic valve based on a detection result of the regenerative current singularity detector.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority from Japanese Patent Application No. 2021-140124 filed on Aug. 30, 2021. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an electronic control device that controls an electromagnetic valve.

BACKGROUND

There is an electromagnetic valve control unit that controls an electromagnetic valve current flowing through an electromagnetic valve when the electromagnetic valve is driven.

SUMMARY

According to an aspect of the present disclosure, an electronic control device is configured to control at least one electromagnetic valve mounted on a vehicle.

DETAILED DESCRIPTION

Examples of the present disclosure will be described below.

According to an example of the present disclosure, an electromagnetic valve control unit is assumable. This electromagnetic valve control unit detects a stuck failure of an electromagnetic valve in accordance with presence or absence of a singularity at a time of rising of an electromagnetic valve current flowing through the electromagnetic valve when the electromagnetic valve is driven.

As a result of detailed studies by the inventor(s), an issue has been found. Specifically, a failed electromagnetic valve is erroneously determined to be normal due to a rapid voltage fluctuation in a direct-current power supply, which applies a power supply voltage to the electromagnetic valve.

According to an example of the present disclosure, an electronic control device is configured to control at least one electromagnetic valve mounted on a vehicle.

The electronic control device comprises a regenerative current detector configured to detect a regenerative current circulating through the at least one electromagnetic valve immediately after power supply to the at least one electromagnetic valve is stopped.

The electronic control device further comprises a regenerative current singularity detector configured to detect a regenerative current singularity that is a singularity in a temporal change of the regenerative current. The electronic control device further comprises a regenerative current failure detector configured to detect a stuck failure of the at least one electromagnetic valve based on a detection result of the regenerative current singularity detector,

This electronic control device of the present disclosure configured as described above detects a regenerative current singularity of a regenerative current that is not affected by the voltage fluctuation in the direct-current power supply. Thus, this electronic control device of the present disclosure enables to suppress occurrence of a situation in which the failed electromagnetic valve is erroneously determined to be normal due to a voltage fluctuation in the direct-current power supply. Thus, the electronic control device enables to improve detection accuracy of an electromagnetic valve failure.

According to another example of the present disclosure, an electronic control device is configured to control at least one electromagnetic valve mounted on a vehicle.

The electronic control device comprises an electromagnetic valve current detector configured to detect an electromagnetic valve current flowing through the at least one electromagnetic valve after power supply to the at least one electromagnetic valve is started.

The electronic control device further comprises a power supply voltage detector configured to detect a power supply voltage of a direct-current power supply that is configured to apply the power supply voltage to the at least one electromagnetic valve.

The electronic control device further comprises an electromagnetic valve current singularity detector configured to detect an electromagnetic valve current singularity that is a singularity in a temporal change of the electromagnetic valve current.

The electronic control device further comprises an electromagnetic valve current failure detector configured to detect a stuck failure of the at least one electromagnetic valve based on a detection result of the electromagnetic valve current singularity detector.

The electronic control device further comprises a failure detection inhibitor configured to determine whether a fluctuation in the power supply voltage has occurred based on a detection result of the power supply voltage detector and, on determination that the fluctuation in the power supply voltage has occurred, inhibit the electromagnetic valve current failure detector from detecting the stuck failure until a preset inhibition release condition is satisfied.

This electronic control device of the present disclosure configured as described above inhibits detection of a stuck failure when a fluctuation in the power supply voltage occurs. Thus, the electronic control device of the present disclosure enables to suppress occurrence of a situation in which the failed electromagnetic valve is erroneously determined to be normal due to a voltage fluctuation in the direct-current power supply, and enables to improve detection accuracy of an electromagnetic valve failure.

According to another example of the present disclosure, an electronic control device is configured to control at least one electromagnetic valve mounted on a vehicle.

The electronic control device comprises an electromagnetic valve current detector and a power supply voltage detector.

The electronic control device further comprises an electromagnetic valve current singularity detector configured to detect an electromagnetic valve current singularity that is a singularity in a temporal change of the electromagnetic valve current.

The electronic control device further comprises an electromagnetic valve current failure detector configured to detect a stuck failure of the at least one electromagnetic valve based on a detection result of the electromagnetic valve current singularity detector.

The electronic control device further comprises an invalidator configured to determine whether a fluctuation in the power supply voltage has occurred based on a detection result of the power supply voltage detector and, on determination that the fluctuation in the power supply voltage has occurred, invalidate at least a detection result of the electromagnetic valve current singularity detector corresponding to a time point at which the fluctuation in the power supply voltage occurs.

The electronic control device of the present disclosure configured as described above invalidates a detection result of an electromagnetic valve current singularity detector when a fluctuation in the power supply voltage occurs. Thus, the electronic control device of the present disclosure enables to suppress occurrence of a situation in which the failed electromagnetic valve is erroneously determined to be normal due to a voltage fluctuation in the direct-current power supply, and enables to improve detection accuracy of an electromagnetic valve failure.

First Embodiment

Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings.

An electronic control unit1(hereinafter, ECU1) according to the present embodiment is mounted on a vehicle and controls an electromagnetic valve2as illustrated inFIG.1. The ECU is an abbreviation for an electronic control unit.

The electromagnetic valve2includes a solenoid coil3and a movable core (not illustrated). A first end of the solenoid coil3is connected to a positive electrode of a vehicle power supply4, and a second end of the solenoid coil3is grounded.

In a non-energized state in which no current is flowing through the solenoid coil3, the electromagnetic valve2according to the present embodiment is in a closed valve state in which the valve is closed. On the other hand, when the electromagnetic valve2according to the present embodiment is in an energized state in which a current flows through the solenoid coil3, a magnetic attraction force for attracting the movable core is generated, the movable core thus moves, and the electromagnetic valve2enters an open valve state in which the valve is opened. The electromagnetic valve2may be configured to be in the open valve state in the non-energized state and to be in the closed valve state in the energized state.

Hereinafter, a state in which a current is flowing through the solenoid coil3in the electromagnetic valve2is referred to as a valve energized state, and a state in which no current is flowing through the solenoid coil3in the electromagnetic valve2is referred to as a valve non-energized state.

The ECU1includes a positive terminal11, a negative terminal12, a diode13, a switching element14, a shunt resistor15, a current detection circuit16, a voltage detection circuit17, a drive circuit18, and a microcomputer19.

The positive terminal11is connected to the first end of the solenoid coil3. The negative terminal12is connected to the second end of the solenoid coil3.

The diode13has an anode connected to the negative terminal12and a cathode connected to the positive terminal11.

The switching element14is a transistor provided on an energization path from the solenoid coil3to a ground. When the switching element14is in an on state, a current flows through the energization path, and when the switching element14is in an off state, no current flows through the energization path. Hereinafter, “the switching element14is in the on state” is also referred to as “the electromagnetic valve2is in the on state”, and “the switching element14is in the off state” is also referred to as “the electromagnetic valve2is in the off state”.

The switching element14has a first end connected to the negative terminal12, and the switching element14has a second end connected to a first end of the shunt resistor15. Then, a second end of the shunt resistor15is grounded.

The current detection circuit16detects a voltage across both ends of the shunt resistor15and detects a current (hereinafter, the electromagnetic valve current) flowing through the electromagnetic valve2on the basis of the voltage value. Then, the current detection circuit16outputs a current detection signal indicating a detection result of the electromagnetic valve current to the microcomputer19.

The voltage detection circuit17detects a voltage at the positive terminal11and outputs a voltage detection signal indicating the detection result to the microcomputer19.

The drive circuit18outputs, to the switching element14, a drive signal for driving the switching element14such that the switching element14is in the on state or the off state on the basis of a control signal output from the microcomputer19.

The microcomputer19includes a CPU21, a ROM22, and a RAM23.

Various functions of the microcomputer19are implemented by the CPU21executing a program stored in a non-transitory tangible storage medium. In this example, the ROM22corresponds to a non-transitory tangible storage medium storing a program. By executing the program, a method corresponding to the program is executed. A part or all of the functions executed by the CPU21may be configured as hardware by one or a plurality of ICs or the like.

A timing chart TC1inFIG.2illustrates temporal changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current in a state where the switching element14is switched from the off state to the on state in a normal state of the electromagnetic valve2.

As illustrated in the timing chart TC1inFIG.2, the vehicle power supply4constantly outputs a power supply voltage having a voltage value VB. When the switching element14is switched from the off state to the on state at time t0, a voltage across both ends of the solenoid coil3of the electromagnetic valve2(hereinafter, the electromagnetic valve voltage) rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases. Then, as the electromagnetic valve current increases, the magnetic attraction force increases, the movable core moves during a period from time t1to time t2, and the electromagnetic valve2enters the open valve state. When the movable core moves, as indicated by a dashed circle CL1, a current singularity that changes from decrease to increase occurs in the temporal change of the electromagnetic valve current.

A timing chart TC2inFIG.2illustrates temporal changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current in a case where the switching element14is switched from the off state to the on state when the electromagnetic valve2is stuck.

As illustrated in the timing chart TC2inFIG.2, the vehicle power supply4constantly outputs the power supply voltage having the voltage value VB. When the switching element14is switched from the off state to the on state at the time t0, the electromagnetic valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases. However, since the movable core does not move due to sticking although the movable core moves during a period from the time t1to the time t2in the normal state, the current singularity does not occur at the time t2.

Similarly to the timing chart TC2, a timing chart TC3inFIG.2illustrates temporal changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current in a case where the switching element14is switched from the off state to the on state when the electromagnetic valve2is stuck. However, the timing chart TC3is different from the timing chart TC2in that a rapid fluctuation of the power supply voltage occurs while the electromagnetic valve current is increasing.

As illustrated in the timing chart TC3inFIG.2, the power supply voltage rapidly decreases from VB [V] to V1[V] at the time t1. As a result, the electromagnetic valve voltage rapidly decreases from Vc [V] to V2[V]. Furthermore, at the time t2, the power supply voltage rapidly increases from V1[V] to VB [V]. As a result, the electromagnetic valve voltage rapidly increases from V2[V] to Vc [V]. Therefore, although the movable core does not move due to sticking, a current singularity occurs at the time t2as indicated by a dashed circle CL2. That is, there is a possibility that it is determined that the electromagnetic valve2is normal despite the occurrence of sticking in the electromagnetic valve2.

Next, a procedure of failure determination processing executed by the CPU21of the microcomputer19will be described. The failure determination processing is processing executed at each arrival of a timing at which the electromagnetic valve2is switched from the valve non-energized state to the valve energized state.

When the failure determination processing is executed, as illustrated inFIG.3, the CPU21first switches the electromagnetic valve2from the off state to the on state in S10. Specifically, the CPU21switches the switching element14from the off state to the on state.

Then, in S20, the CPU21reads the power supply voltage. Specifically, the CPU21acquires a voltage detection signal from the voltage detection circuit17, calculates a power supply voltage value on the basis of the acquired voltage detection signal, and stores the calculated power supply voltage value in the RAM23.

Then, in S30, the CPU21reads an electromagnetic valve voltage. Specifically, the CPU21acquires a current detection signal from the current detection circuit16, calculates an electromagnetic valve current value on the basis of the acquired current detection signal, and stores the calculated electromagnetic valve current value in the RAM23.

Then, in S40, the CPU21determines whether there is a fluctuation in the power supply voltage. Specifically, the CPU21determines whether a difference between the power supply voltage value calculated in previous S20and the power supply voltage value calculated in the current S20is greater than or equal to a voltage fluctuation determination value set in advance.

When there is a fluctuation in the power supply voltage, the CPU21switches the electromagnetic valve2from the on state to the off state in S50. Specifically, the CPU21switches the switching element14from the on state to the off state.

In S60, the CPU21reads the electromagnetic valve signal and stands by until the electromagnetic valve current value becomes 0. When the electromagnetic valve current value becomes 0, the CPU21proceeds to S10.

When there is no fluctuation in the power supply voltage in S40, the CPU21determines in S50whether a current singularity has been detected. Specifically, the CPU21determines that a current singularity has been detected when the electromagnetic valve current value continuously decreases during a period from before a preset first singularity determination time to the previous failure determination processing, and the electromagnetic valve current value changes from decrease to increase in the current failure determination processing.

When a current singularity has not been detected, the CPU21determines in S80whether the electromagnetic valve current value is saturated. Specifically, the CPU21calculates a difference between the electromagnetic valve current value calculated in previous S30and the electromagnetic valve current value calculated in current S30(hereinafter, an electromagnetic valve current difference), and sequentially stores the calculated electromagnetic valve current values in the RAM23. Then, on the basis of the plurality of stored electromagnetic valve current values, the CPU21determines that the electromagnetic valve current value is saturated when the electromagnetic valve current value continues to be less than a preset saturation determination value for a preset saturation determination time.

Here, when the electromagnetic valve current value is not saturated, the CPU21proceeds to S20.

On the other hand, when the electromagnetic valve current value is saturated, the CPU21sets an electromagnetic valve failure flag F1provided in the RAM23in S90, and ends the failure determination processing. In the following description, setting a flag indicates setting a value of the flag to 1, and clearing a flag indicates setting a value of the flag to 0.

When the current singularity is detected in S70, the CPU21clears the electromagnetic valve failure flag F1in S100, and ends the failure determination processing.

A timing chart TC4inFIG.4illustrates temporal changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current in a state where a rapid fluctuation in the power supply voltage occurs in the normal state of the electromagnetic valve2according to the first embodiment.

As illustrated in the timing chart TC4inFIG.4, the vehicle power supply4constantly outputs the power supply voltage having the voltage value VB. When the switching element14is switched from the off state to the on state at time t10, the electromagnetic valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases.

Then, at time t11, the power supply voltage rapidly decreases from VB [V] to V1[V]. As a result, the electromagnetic valve voltage rapidly decreases from Vc [V] to V2[V], and the electromagnetic valve current also decreases.

When the switching element14is switched from the on state to the off state at time t12by the power supply voltage rapidly decreasing at the time t11, the electromagnetic valve voltage rapidly decreases from V2[V] to 0 [V], and the electromagnetic valve current gradually decreases.

When the electromagnetic valve current becomes 0, the switching element14is switched from the off state to the on state at time t13, and the electromagnetic valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases. Then, as the electromagnetic valve current increases, the magnetic attraction force increases, the movable core moves, and a current singularity occurs at time t14.

The ECU1configured as described above controls the electromagnetic valve2mounted on the vehicle, and includes the shunt resistor15, the current detection circuit16, the voltage detection circuit17, and the microcomputer19.

The shunt resistor15and the current detection circuit16detect the electromagnetic valve current flowing through the electromagnetic valve2after power supply to the electromagnetic valve2is started. The voltage detection circuit17detects a power supply voltage of the vehicle power supply4.

The microcomputer19detects a current singularity in a temporal change of the electromagnetic valve current (hereinafter, the electromagnetic valve current singularity).

The microcomputer19detects a stuck failure of the electromagnetic valve2on the basis of a detection result of the electromagnetic valve current singularity.

The microcomputer19determines whether a fluctuation in the power supply voltage has occurred on the basis of the detection result of the voltage detection circuit17, and inhibits a detection of a stuck failure until a preset inhibition release condition is satisfied when determining that a fluctuation in the power supply voltage has occurred. The inhibition release condition in the present embodiment is that the electromagnetic valve current becomes 0.

The ECU1as described above enables to suppress the occurrence of a situation in which the failed electromagnetic valve2is erroneously determined to be normal due to a voltage fluctuation in the vehicle power supply4, and enables to improve detection accuracy of an electromagnetic valve failure.

In the embodiment described above, the ECU1corresponds to an electronic control unit, the shunt resistor15and the current detection circuit16correspond to an electromagnetic valve current detector, the vehicle power supply4corresponds to a direct-current power supply, and the voltage detection circuit17corresponds to a power supply voltage detector.

Further, S70corresponds to processing as an electromagnetic valve current singularity detector, S90and S100correspond to processing as an electromagnetic valve current failure detector, and S40to S60correspond to processing as a failure detection inhibitor.

Second Embodiment

Hereinafter, a second embodiment of the present disclosure will be described with reference to the drawings. In the second embodiment, differences from the first embodiment will be described. Common configurations are denoted by the same reference numerals.

The ECU1according to the second embodiment is different from the ECU1according to the first embodiment in that the failure determination processing is changed.

Next, a procedure of the failure determination processing according to the second embodiment will be described.

When the failure determination processing according to the second embodiment is executed, the CPU21first switches the electromagnetic valve2from the off state to the on state in S210as illustrated inFIG.5.

Then, in S220, the CPU21reads the power supply voltage. Then, in S230, the CPU21reads the electromagnetic valve current.

Then, in S240, the CPU21determines whether here is a fluctuation in the power supply voltage.

Here, when there is a fluctuation in the power supply voltage, the CPU21sets a voltage stabilization standby flag F2and an invalid flag F3provided in the RAM23in S250. The CPU21resets (that is, sets to 0) a standby timer provided in the RAM23in S260, and proceeds to S220.

When there is no fluctuation in the power supply voltage in S240, the CPU21determines in S270whether the voltage stabilization standby flag F2has been set, Here, when the voltage stabilization standby flag F2has been set, the CPU21increments (that is, adds 1 to) the standby timer in S280.

Then, in S290, the CPU21determines whether a preset standby time has elapsed. Specifically, the CPU21determines whether a value of the standby timer is greater than or equal to an equivalent standby time value that is equivalent to the standby time.

Here, when the standby time has not elapsed, the CPU21proceeds to S220. On the other hand, when the standby time has elapsed, the CPU21clears the voltage stabilization standby flag F2in S300, and proceeds to S220.

When the voltage stabilization standby flag F2has been cleared in S270, the CPU21determines in S310whether a current singularity has been detected. When a current singularity has not been detected, the CPU21determines in S320whether the electromagnetic valve current value is saturated.

Here, when the electromagnetic valve current value is not saturated, the CPU21proceeds to S220. When the electromagnetic valve current value is saturated, the CPU21determines in S330whether the invalid flag F3has been set.

Here, when the invalid flag F3has been set, the CPU21dears the invalid flag F3in S340. Then, the CPU21switches the electromagnetic valve2from the on state to the off state in S350. In S360, the CPU21stands by until the electromagnetic valve current value becomes 0, and proceeds to S210when the electromagnetic valve current value becomes 0.

When the invalid flag F3has been cleared in S330, the CPU21clears the electromagnetic valve failure flag F1in S370, and ends the failure determination processing.

When the current singularity is detected in S310, the CPU21clears the electromagnetic valve failure flag F1in S380, and ends the failure determination processing.

A timing chart TC5inFIG.6illustrates temporal changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current in a state where a rapid fluctuation in the power supply voltage occurs in the normal state of the electromagnetic valve2according to the second embodiment.

As illustrated in the timing chart TC5inFIG.6, the vehicle power supply4constantly outputs the power supply voltage having the voltage value VB. When the switching element14is switched from the off state to the on state at time t20, the electromagnetic valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases.

Then, at time t21, the power supply voltage rapidly decreases from VB [V] to V1[V]. As a result, the voltage stabilization standby flag F2and the invalid flag F3are set. The electromagnetic valve voltage rapidly decreases from Vc [V] to V2[V], and the electromagnetic valve current also decreases.

Furthermore, at the time t22, the power supply voltage rapidly increases from V1[V] to VB [V]. Thus, the electromagnetic valve voltage rapidly increases from V2[V] to Vc [V], and a current singularity occurs.

However, the invalid flag F3is set at the time t22.

Thereafter, the voltage stabilization standby flag F2is cleared at time t23while the electromagnetic valve current gradually increases. Then, as the electromagnetic valve current increases, the magnetic attraction force increases, the movable core moves, and a current singularity occurs at time t24. As a result, the electromagnetic valve failure flag F1is cleared.

The ECU1configured as described above controls the electromagnetic valve2mounted on the vehicle, and includes the shunt resistor15, the current detection circuit16, the voltage detection circuit17, and the microcomputer19.

The microcomputer19detects an electromagnetic valve current singularity in a temporal change of the electromagnetic valve current.

The microcomputer19detects a stuck failure of the electromagnetic valve2on the basis of a detection result of the electromagnetic valve current singularity.

The microcomputer19determines whether a fluctuation in the power supply voltage VB has occurred on the basis of the detection result of the voltage detection circuit17, and inhibits a detection of a stuck failure until a preset inhibition release condition is satisfied when determining that a fluctuation in the power supply voltage VB has occurred. The inhibition release condition according to the present embodiment is that a preset standby time elapses after the fluctuation in the power supply voltage VB occurs.

The ECU1as described above enables to suppress the occurrence of a situation in which the failed electromagnetic valve2is erroneously determined to be normal due to a voltage fluctuation in the vehicle power supply4, and enables to improve detection accuracy of an electromagnetic valve failure.

In the embodiment described above, S310corresponds to processing as the electromagnetic valve current singularity detector, S370and S380correspond to processing as the electromagnetic valve current failure detector, S240to S300correspond to processing as the failure detection inhibitor, and the standby time corresponds to an inhibition time.

Third Embodiment

Hereinafter, a third embodiment of the present disclosure will be described with reference to the drawings. In the third embodiment, differences from the first embodiment will be described. Common configurations are denoted by the same reference numerals.

The ECU1according to the third embodiment is different from the ECU1according to the first embodiment in that the failure determination processing is changed.

Next, a procedure of the failure determination processing according to the third embodiment will be described.

When the failure determination processing according to the third embodiment is executed, the CPU21first switches the electromagnetic valve2from the off state to the on state in S410as illustrated inFIG.7.

Then, in S420, the CPU21reads the power supply voltage. In S430, the CPU21reads the electromagnetic valve current.

In S440, the CPU21determines whether a current singularity has been detected. Here, when a current singularity has been detected, the CPU21determines in S450whether there is a fluctuation in the power supply voltage. Here, when there is a fluctuation in the power supply voltage, the CPU21sets the invalid flag F3in S460and proceeds to S420. On the other hand, when there is no fluctuation in the power supply voltage, the CPU21clears the electromagnetic valve failure flag F1in S470, and ends the failure determination processing.

When a current singularity has not been detected in S440, the CPU21determines in S480whether the electromagnetic valve current value is saturated. Here, when the electromagnetic valve current value is not saturated, the CPU21proceeds to S420. When the electromagnetic valve current value is saturated, the CPU21determines in S490whether the invalid flag F3has been set.

Here, when the invalid flag F3has been set, the CPU21clears the invalid flag F3in S500. Then, the CPU21switches the electromagnetic valve2from the on state to the off state in S510. In S520, the CPU21stands by until the electromagnetic valve current value becomes 0, and proceeds to S410when the electromagnetic valve current value becomes 0.

When the invalid flag F3has been cleared in S490, the CPU21sets the electromagnetic valve failure flag F1in S530, and ends the failure determination processing.

A timing chart TC6inFIG.8illustrates temporal changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current in a state where a rapid fluctuation in the power supply voltage occurs in the normal state of the electromagnetic valve2according to the third embodiment.

As illustrated in the timing chart TC6inFIG.8, the vehicle power supply4constantly outputs the power supply voltage having the voltage value VB. When the switching element14is switched from the off state to the on state at time t30, the electromagnetic valve voltage rapidly increases from 0 [V] to Vc [V]. As a result, the electromagnetic valve current gradually increases.

Then, at time t31, the power supply voltage rapidly decreases from VB [V] to V1[V]. As a result, the invalid flag F3is set. The electromagnetic valve voltage rapidly decreases from Vc [V] to V2[V], and the electromagnetic valve current also decreases.

Furthermore, at the time t32, the power supply voltage rapidly increases from V1[V] to VB [V]. Thus, the electromagnetic valve voltage rapidly increases from V2[V] to Vc [V], and a current singularity occurs.

However, the invalid flag F3has been set at the time t32.

Then, as the electromagnetic valve current increases, the magnetic attraction force increases, the movable core moves, and a current singularity occurs at time t33. Since there has not been a fluctuation in the power supply voltage by this point of time, the electromagnetic valve failure flag F1is cleared.

The ECU1configured as described above controls the electromagnetic valve2mounted on the vehicle, and includes the shunt resistor15, the current detection circuit16, the voltage detection circuit17, and the microcomputer19.

The microcomputer19detects an electromagnetic valve current singularity in a temporal change of the electromagnetic valve current.

The microcomputer19detects a stuck failure of the electromagnetic valve2on the basis of a detection result of the electromagnetic valve current singularity.

The microcomputer19determines whether a fluctuation in the power supply voltage has occurred on the basis of the detection result of the voltage detection circuit17. When determining that a fluctuation in the power supply voltage has occurred, the microcomputer19invalidates at least the detection result of the electromagnetic valve current singularity corresponding to a time point at which the fluctuation in the power supply voltage has occurred.

The ECU1as described above enables to suppress the occurrence of a situation in which the failed electromagnetic valve2is erroneously determined to be normal due to a voltage fluctuation in the vehicle power supply4, and enables to improve detection accuracy of an electromagnetic valve failure.

In the embodiment described above, S440corresponds to processing as the electromagnetic valve current singularity detector, S470and S530correspond to processing as the electromagnetic valve current failure detector, S450and S460correspond to processing as an invalidator.

Fourth Embodiment

Hereinafter, a fourth embodiment of the present disclosure will be described with reference to the drawings. In the fourth embodiment, differences from the first embodiment will be described. Common configurations are denoted by the same reference numerals.

The ECU1according to the fourth embodiment is different from the ECU1according to the first embodiment in that the configuration of the ECU1is changed and that regenerative current failure determination processing is executed instead of the failure determination processing.

As illustrated inFIG.9, the ECU1according to the fourth embodiment is different from the ECU1according to the first embodiment in that the voltage detection circuit17is omitted and that connections of the diode13, the switching element14, and the shunt resistor15are changed.

That is, the diode13has the anode connected to the second end of the shunt resistor15and the cathode connected to the positive terminal11. The first end of the switching element14is connected to the second end of the shunt resistor15, and the second end of the switching element14is grounded. The first end of the shunt resistor15is connected to the negative terminal12.

When the switching element14is in the on state, a current flows from the vehicle power supply4to the solenoid coil3. When the switching element14is in the off state, energy accumulated in the solenoid coil3when the switching element14is in the on state causes a current to continuously flow (that is, circulate) to the solenoid coil3via the diode13.

The same current as the current flowing through the diode13flows through the shunt resistor15. Therefore, the current detection circuit16detects the current (that is, regenerative current) flowing through the diode13immediately after the switching element14is switched from the on state to the off state.

Next, a procedure of the regenerative current failure determination processing according to the fourth embodiment will be described. The regenerative current failure determination processing is processing executed at each arrival of a timing at which the electromagnetic valve2is switched from the valve energized state to the valve non-energized state.

When the regenerative current failure determination processing is executed, as illustrated inFIG.10, the CPU21first switches the electromagnetic valve2from the on state to the off state in S610. In S620, the CPU21reads the regenerative current. Specifically, the CPU21acquires a current detection signal from the current detection circuit16, calculates a regenerative current value on the basis of the acquired current detection signal, and stores the calculated regenerative current value in the RAM23.

In S630, the CPU21determines whether a current singularity has been detected. Specifically, the CPU21determines that a current singularity has been detected when the regenerative current value continuously increases during a period from before a preset second singularity determination time to the previous regenerative current failure determination processing, and the regenerative current value changes from increase to decrease in the current regenerative current failure determination processing.

Here, when the current singularity has been detected, the CPU21clears the electromagnetic valve failure flag F1in S640, and ends the regenerative current failure determination processing. On the other hand, when a current singularity has not been detected, the CPU21determines in S650whether the regenerative current value has reached 0. Here, when the regenerative current value has not reached 0, the CPU21proceeds to S620. On the other hand, when the regenerative current value has reached 0, the CPU21sets the electromagnetic valve failure flag F1in S640, and ends the regenerative current failure determination processing.

A timing chart TC7inFIG.11illustrates temporal changes of the power supply voltage, the electromagnetic valve voltage, and the electromagnetic valve current in a state where a rapid fluctuation in the power supply voltage occurs in the normal state of the electromagnetic valve2according to the fourth embodiment.

As illustrated in the timing chart TC7inFIG.11, the vehicle power supply4constantly outputs the power supply voltage having the voltage value VB. When the switching element14is switched from the on state to the off state at time t40, the electromagnetic valve voltage rapidly decreases from Vc [V] to 0 [V]. As a result, the electromagnetic valve current gradually decreases.

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

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

Then, as the electromagnetic valve current decreases, the magnetic attraction force decreases. Then, the movable core moves, and the electromagnetic valve2enters the closed valve state. The movement of the movable core generates a current singularity that changes from increase to decrease at time t43.

FIG.12is a diagram illustrating a configuration of the ECU1to which a Zener diode31is connected in order to damp a surge generated when the electromagnetic valve2is turned into the off state.

In the ECU1illustrated inFIG.12, an anode of the Zener diode31is grounded, and a cathode of the Zener diode31is connected to a connection point between the switching element14and the shunt resistor15. The diode13is omitted.

A timing chart TC8inFIG.13illustrates temporal changes of a voltage of the negative terminal12(hereinafter, negative terminal voltage) and the electromagnetic valve current in a case where the electromagnetic valve2is switched from the on state to the off state. A line L1of the timing chart TC8indicates a temporal change of the negative terminal voltage in the ECU1according to the fourth embodiment. A line L2indicates a temporal change of the negative terminal voltage in the ECU1illustrated inFIG.12. A line L3indicates a temporal change of the electromagnetic valve current in the ECU1according to the fourth embodiment. A line L4indicates a temporal change of the electromagnetic valve current in the ECU1illustrated inFIG.12.

As illustrated inFIG.12, when the switching element14is switched from the on state to the off state at time t50, the negative terminal voltage rapidly increases, and the electromagnetic valve current gradually decreases. The negative terminal voltage of the ECU1illustrated inFIG.12is larger than the negative terminal voltage of the ECU1according to the fourth embodiment. The electromagnetic valve current of the ECU1illustrated inFIG.12decreases faster than the electromagnetic valve current of the ECU1according to the fourth embodiment.

Then, when the movable core moves between time t51and time t52, a current singularity occurs in the ECU1according to the fourth embodiment. However, in the ECU1illustrated inFIG.12, the electromagnetic valve current is consumed before the movable core moves, and a current singularity does not occur. Therefore, in order to generate a current singularity, it is desirable not to use the Zener diode31.

A timing chart TC9inFIG.14illustrates a temporal change of the electromagnetic valve current in a state where the electromagnetic valve2is switched from the on state to the off state. A line L11of the timing chart TC9indicates a temporal change in the electromagnetic valve current when the diode13is a rectifier diode. A line L12of the timing chart TC9indicates a temporal change in the electromagnetic valve current when the diode13is a Schottky barrier diode. A forward voltage Vf of the rectifier diode is larger than a forward voltage of the Schottky barrier diode. In the present embodiment, the forward voltage Vf of the rectifier diode is 0.7 V, and the forward voltage Vf of the Schottky barrier diode is 0.4 V.

As illustrated inFIG.14, when the switching element14is switched from the on state to the off state at time t60, the electromagnetic valve current gradually decreases. However, when the diode13is a rectifier diode, the electromagnetic valve current decreases faster than when the diode13is a Schottky barrier diode.

When the diode13is a rectifier diode, the movable core moves during a period from time t61to time t62. When the diode13is a Schottky barrier diode, the movable core moves during a period from time t63to time t64. As illustrated inFIG.14, by using a Schottky barrier diode for the diode13, it is possible to increase lifting of the electromagnetic valve current during a valve operation, and remarkably generate a current singularity.

The ECU1configured as described above controls the electromagnetic valve2mounted on the vehicle, and includes the shunt resistor15, the current detection circuit16, and the microcomputer19.

The shunt resistor15and the current detection circuit16detect the regenerative current circulating through the electromagnetic valve2immediately after the power supply to the electromagnetic valve2is stopped.

The microcomputer19detects a current singularity in a temporal change of the regenerative current (hereinafter, the regenerative current singularity). Then, the microcomputer19detects a stuck failure of the electromagnetic valve2on the basis of a detection result of the regenerative current singularity.

The ECU1as described above detects a regenerative current singularity of a regenerative current that is not affected by a voltage fluctuation in the vehicle power supply4. Thus, the ECU1enables to suppress the occurrence of a situation in which the failed electromagnetic valve2is erroneously determined to be normal due to a voltage fluctuation in the vehicle power supply4, and enables to improve the detection accuracy of an electromagnetic valve failure.

The ECU1includes the diode13through which a regenerative current flows. As a result, the ECU1enables to gradually reduce the regenerative current, and enables to easily generate a regenerative current singularity in the temporal change of the regenerative current.

In the embodiment described above, the shunt resistor15and the current detection circuit16correspond to a regenerative current detector, S630corresponds to processing as a regenerative current singularity detector, S640and S660correspond to processing as a regenerative current failure detector, and the diode13corresponds to a freewheeling diode.

Fifth Embodiment

Hereinafter, a fifth embodiment of the present disclosure will be described with reference to the drawings. In the fifth embodiment, differences from the fourth embodiment will be described. Common configurations are denoted by the same reference numerals.

The ECU1according to the fifth embodiment is different from the ECU1according to the fourth embodiment in that the configuration of the ECU1is changed and that the failure determination processing is executed instead of the regenerative current failure determination processing.

The ECU1according to the fifth embodiment is different from the ECU1according to the fourth embodiment in that the voltage detection circuit17is added as illustrated inFIG.15. The voltage detection circuit17detects a voltage at the positive terminal11and outputs a voltage detection signal indicating the detection result to the microcomputer19.

Next, a procedure of the failure determination processing according to the fifth embodiment will be described. The failure determination processing is processing executed at each arrival of a timing at which the electromagnetic valve2is switched from the valve non-energized state to the valve energized state.

As illustrated inFIG.16, the failure determination processing according to the fifth embodiment is different from the failure determination processing according to the third embodiment in that the processings of S510and S520are omitted and the processing of S525is added.

That is, when the processing of S500ends, the CPU21executes the regenerative current failure determination processing according to the fourth embodiment in S525, and ends the failure determination processing.

The ECU1configured as described above controls the electromagnetic valve2mounted on the vehicle, and includes the shunt resistor15, the current detection circuit16, the voltage detection circuit17, and the microcomputer19.

The shunt resistor15and the current detection circuit16detect the electromagnetic valve current flowing through the electromagnetic valve2after power supply to the electromagnetic valve2is started. The voltage detection circuit17detects a power supply voltage of the vehicle power supply4.

The microcomputer19detects an electromagnetic valve current singularity in a temporal change of the electromagnetic valve current.

The microcomputer19detects a stuck failure of the electromagnetic valve2on the basis of a detection result of the electromagnetic valve current singularity.

The microcomputer19determines whether a fluctuation in the power supply voltage has occurred on the basis of the detection result of the voltage detection circuit17. When determining that a fluctuation in the power supply voltage has occurred, the microcomputer19invalidates at least the detection result of the electromagnetic valve current singularity corresponding to a time point at which the fluctuation in the power supply voltage has occurred.

The shunt resistor15and the current detection circuit16detect the regenerative current circulating through the electromagnetic valve2immediately after the power supply to the electromagnetic valve2is stopped.

The microcomputer19detects a regenerative current singularity in the temporal change of the regenerative current. Then, the microcomputer19detects a stuck failure of the electromagnetic valve2on the basis of a detection result of the regenerative current singularity.

The ECU1as described above invalidates the detection result of the electromagnetic valve current singularity when a fluctuation in the power supply voltage occurs, and detects a regenerative current singularity of a regenerative current that is not affected by the voltage fluctuation in the vehicle power supply4. Thus, the ECU1enables to suppress the occurrence of a situation in which the failed electromagnetic valve2is erroneously determined to be normal due to a voltage fluctuation in the vehicle power supply4, and enables to improve the detection accuracy of an electromagnetic valve failure.

In the embodiment described above, S440corresponds to processing as the electromagnetic valve current singularity detector, S470and S530correspond to processing as the electromagnetic valve current failure detector, S450and S560correspond to processing as an invalidator.

Further, S525corresponds to processing as the regenerative current singularity detector and the regenerative current failure detector.

Sixth Embodiment

Hereinafter, a sixth embodiment of the present disclosure will be described with reference to the drawings. In the sixth embodiment, differences from the fourth embodiment will be described. Common configurations are denoted by the same reference numerals.

The ECU1according to the sixth embodiment is different from the ECU1according to the fourth embodiment in that the configuration of the ECU1is changed.

As illustrated inFIG.17, the ECU1according to the sixth embodiment is different from the ECU1according to the fourth embodiment in that the connections of the diode13, the switching element14, and the shunt resistor15are changed.

That is, the diode13has the anode connected to the negative terminal12and the cathode connected to the second end of the shunt resistor15. The first end of the switching element14is connected to the negative terminal12, and the second end of the switching element14is grounded. The first end of the shunt resistor15is connected to the positive terminal11.

In the ECU1configured as described above, the shunt resistor15and the current detection circuit16detect the regenerative current flowing in the energization path between the diode13and the vehicle power supply4that applies the power supply voltage to the electromagnetic valve2.

Similarly to the ECU1according to the fourth embodiment, the ECU1described above enables to suppress the occurrence of a situation in which the failed electromagnetic valve2is erroneously determined to be normal due to a voltage fluctuation in the vehicle power supply4, and enables to improve detection accuracy of an electromagnetic valve failure.

Seventh Embodiment

Hereinafter, a seventh embodiment of the present disclosure will be described with reference to the drawings. In the seventh embodiment, differences from the sixth embodiment will be described. Common configurations are denoted by the same reference numerals.

As illustrated inFIG.18, the ECU1according to the seventh embodiment controls electromagnetic valves2a,2b,and2c.The electromagnetic valves2a,2b,and2care the same as the electromagnetic valve2, and include solenoid coils3a,3b,and3c,respectively, and a movable core (not illustrated). First ends of the solenoid coils3a,3b,and3care connected to a positive electrode of the vehicle power supply4, and second ends of the solenoid coils3a,3b,and3care grounded.

The ECU1includes the positive terminal11, negative terminals12a,12b,and12c,diodes13a,13b,and13c,switching elements14a,14b,and14c,the shunt resistor15, the current detection circuit16, drive circuits18a,18b,and18c,and the microcomputer19.

The positive terminal11is connected to the first ends of the solenoid coils3a,3b,and3c.The negative terminals12a,12b,and12care connected to the second ends of the solenoid coils3a,3b,and3c,respectively.

Each of the diodes13a,13b,and13cis the same as the diode13, and has an anode connected to each of the negative terminals12a,12b,and12cand a cathode connected to the second end of the shunt resistor15.

Each of the switching elements14a,14b,and14cis the same as the switching element14, and is a transistor provided on an energization path from each of the solenoid coils3a,3b,and3cto the ground.

First ends of the switching elements14a,14b,and14care connected to the negative terminals12a,12b,and12c,respectively. Second ends of the switching elements14a,14b,and14care grounded. The first end of the shunt resistor15is connected to the positive terminal11.

The drive circuits18a,18b,and18coutput, to the switching elements14a,14b,and14c,respectively, a drive signal for driving the switching elements14a,14b,and14csuch that the switching elements14a,14b,and14care in the on state or the off state on the basis of a control signal output from the microcomputer19.

A timing chart TC10inFIG.19illustrates temporal changes of voltages across both ends of the solenoid coils3a,3b,and3cin a case where the electromagnetic valves2a,2b,and2care switched from the on state to the off state. Hereinafter, the voltages across both ends of the solenoid coils3a,3b,and3care referred to as first, second, and third electromagnetic valve voltages, respectively.

As illustrated inFIG.19, when the switching element14ais switched from the on state to the off state at time t70, the first electromagnetic valve voltage rapidly decreases from Vc [V] to 0 [V]. As a result, the current detected by the current detection circuit16(hereinafter, detected current) gradually decreases, and a current singularity occurs at time t71.

When the switching element14bis switched from the on state to the off state at time t72, the second electromagnetic valve voltage rapidly decreases from Vc [V] to 0 [V]. As a result, the detected current gradually decreases, and a current singularity occurs at time t73.

When the switching element14cis switched from the on state to the off state at time t74, the third electromagnetic valve voltage rapidly decreases from Vc [V] to 0 [V]. As a result, the detected current gradually decreases, and a current singularity occurs at time t75.

hi the ECU1configured as described above, the shunt resistor15and the current detection circuit16detect a regenerative current of each of a plurality of the electromagnetic valves2a,2b,and2c.The ECU1as described above does not include three current detection circuits16corresponding to the electromagnetic valves2a,2b,and2c,and thus enables to have a simplified configuration.

Eighth Embodiment

Hereinafter, an eighth embodiment of the present disclosure will be described with reference to the drawings. In the eighth embodiment, differences from the fourth embodiment will be described. Common configurations are denoted by the same reference numerals.

As illustrated inFIG.20, the ECU1according to the eighth embodiment is different from the ECU1according to the fourth embodiment in that a terminal state detection circuit50is added and terminal failure detection processing is executed.

The terminal state detection circuit50includes resistors51and52and a diode53. The resistor51has a first end connected to an internal power supply6. The resistor52has a first end connected to the microcomputer19. The resistors51and52have second ends connected to an anode of the diode53. The diode53has a cathode connected to the second end of the shunt resistor15.

In the terminal state detection circuit50configured as described above, when a voltage level of the negative terminal12is at a low level, a voltage level of a connection end with microcomputer19(that is, the first end of the resistor52) is at a low level. When the voltage level of the negative terminal12is at a high level, the voltage level of the connection end with the microcomputer19is at a high level.

In other words, in the terminal state detection circuit50, when the voltage level of the negative terminal12is at the low level, a terminal state detection signal for the voltage level to be the low level is output to microcomputer19. In the terminal state detection circuit50, when the voltage level of the negative terminal12is at the high level, a terminal state detection signal for the voltage level to be the high level is output to microcomputer19.

As illustrated in a first row C1inFIG.21, when the switching element14is in the off state in a case where the ECU1and the electromagnetic valve2are normal, the electromagnetic valve2is in the off state. Then, no current flows through the shunt resistor15, and the voltage level of the negative terminal12turns into the high level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the low level. The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the high level.

As illustrated in a second row C2, when the switching element14is in the on state in a case where the ECU1and the electromagnetic valve2are normal, the electromagnetic valve2is in the on state. Then, a current flows through the shunt resistor15, and the voltage level of the negative terminal12turns into the low level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the high level. The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the low level.

Further, as illustrated in a third row C3and a fourth row C4, in a state in which a battery short-circuit failure in which the negative terminal12and the vehicle power supply4are short-circuited occurs, the electromagnetic valve2is in the off state regardless of whether the switching element14is in the off state or the on state.

Then, as illustrated in the third row C3, when the switching element14is in the off state, no current flows through the shunt resistor15, and the voltage level of the negative terminal12is at the high level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the low level.

The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the high level.

When the switching element14is in the on state in a state where a battery short-circuit failure occurs in which the negative terminal12and the vehicle power supply4are short-circuited, a current flows through the shunt resistor15, and the voltage level of the negative terminal12is at the low level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the high level. The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the low level.

Then, when an overcurrent flows through the shunt resistor15, the switching element14enters the off state by an IPD built in the drive circuit18. Thus, no current flows through the shunt resistor15, and the voltage level of the negative terminal12turns into the high level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the low level. The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the high level. IPD stands for intelligent power device.

Thereafter, when the overcurrent of the shunt resistor15is eliminated, the switching element14returns to the on state. Then, when an overcurrent flows through the shunt resistor15again, the switching element14enters the off state by the IPD built in the drive circuit18.

Therefore, as illustrated in the fourth row C4, when the switching element14is in the on state in a state where the battery short-circuit failure occurs, a state where the current detection signal is at the low level and the terminal state detection signal is at the high level and a state where the current detection signal is at the high level and the terminal state detection signal is at the low level are alternately repeated.

As illustrated in a fifth row C5and a sixth row C6, in a state where a ground short-circuit failure in which the negative terminal12and the ground are short-circuited occurs, the electromagnetic valve2is in the on state whether the switching element14is in the off state or the on state. Then, whether the switching element14is in the off state or in the on state, no current flows through the shunt resistor15, and the voltage level of the negative terminal12is at the low level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the low level. The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the low level.

As illustrated in a seventh row C7and an eighth row C8, in a state where an open failure in which the negative terminal12is opened occurs, the electromagnetic valve2is in the off state whether the switching element14is in the off state or the on state.

Then, as illustrated in the seventh row C7, when the switching element14is in the off state, no current flows through the shunt resistor15, and the voltage level of the negative terminal12is at the high level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the low level.

The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the high level.

Then, as illustrated in the eighth row C8, when the switching element14is in the on state, no current flows through the shunt resistor15, and the voltage level of the negative terminal12is at the low level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the low level. The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the low level.

Next, a procedure of the terminal failure detection processing executed by the CPU21of the microcomputer19will be described. The terminal failure detection processing is processing repeatedly executed during the operation of the microcomputer19.

When the terminal failure detection processing is executed, as illustrated inFIG.22, the CPU21first determines in S610whether the switching element14is in the off state. Here, when the switching element14is not in the off state, the processing of S610is repeated to stand by until the switching element14is in the off state.

Then, when the switching element14enters the off state, the CPU21detects a ground short-circuit failure in S620. Specifically, the CPU21determines whether the voltage level of the negative terminal12is at the low level on the basis of the terminal state detection signal. Here, when the voltage level of the negative terminal12is at the low level, the CPU21sets a ground short-circuit failure flag F11provided in the RAM23. Here, when the voltage level of the negative terminal12is at the high level, the CPU21clears the ground short-circuit failure flag F11.

When the processing of S620ends, the CPU21determines in S630whether the switching element14is in the on state. Here, when the switching element14is not in the on state, the processing of S630is repeated to stand by until the switching element14is in the on state.

Then, when the switching element14enters the on state, the CPU21detects a battery short-circuit failure in S640. Specifically, on the basis of the terminal state detection signal, the CPU21determines whether the voltage level of the negative terminal12is repeatedly switched between the high level and the low level. Here, when the voltage level of the negative terminal12is repeatedly switched between the high level and the low level, the CPU21sets a battery short-circuit failure flag F12provided in the RAM23. On the other hand, when the voltage level of the negative terminal12is not repeatedly switched between the high level and the low level, the CPU21clears the battery short-circuit failure flag F12.

When the processing of S640ends, the CPU21detects an open failure in S650, and ends the terminal failure detection processing. Specifically, the CPU21determines whether a current is flowing through the shunt resistor15on the basis of the current detection signal. Here, when no current is flowing through the shunt resistor15, the CPU21sets an open failure flag F13provided in the RAM23. Here, when a current is flowing through the shunt resistor15, the CPU21dears the open failure flag F13.

The ECU1configured as described above includes the positive terminal11the negative terminal12, and the terminal state detection circuit50.

The positive terminal11is connected to a first end of the electromagnetic valve2, the first end being an end connected to the vehicle power supply4that applies the power supply voltage VB to the electromagnetic valve2. The negative terminal12is connected to a second end of the electromagnetic valve2, the second end being an end connected to the ground.

The terminal state detection circuit50includes the resistor51and the diode53, and detects the voltage level at the negative terminal12.

The shunt resistor15and the current detection circuit16detect a regenerative current flowing through the energization path between the negative terminal12and the diode13.

The microcomputer19detects a ground short-circuit failure in the negative terminal12on the basis of a detection result of the terminal state detection circuit50when the application of the power supply voltage to the electromagnetic valve2is stopped.

The microcomputer19detects a battery short-circuit failure in the negative terminal12on the basis of the detection result of the terminal state detection circuit50while power is supplied to the electromagnetic valve2.

The microcomputer19detects an open failure in the negative terminal12on the basis of the detection result of the terminal state detection circuit50while power is supplied to the electromagnetic valve2.

The ECU1as described above enables to detect a ground short-circuit failure, a battery short-circuit failure, and an open failure at the negative terminal12.

In the embodiment described above, the terminal state detection circuit50correspods to a terminal state detector, the resistor51corresponds to a pull-up resistor, S620corresponds to processing as a ground short-circuit failure detector, S640corresponds to processing as a battery short-circuit failure detector, and S650corresponds to processing as a first open failure detector.

Ninth Embodiment

Hereinafter, a ninth embodiment of the present disclosure will be described with reference to the drawings. In the ninth embodiment, differences from the sixth embodiment will be described. Common configurations are denoted by the same reference numerals.

As illustrated inFIG.23, the ECU1according to the ninth embodiment is different from the ECU1according to the sixth embodiment in that the terminal state detection circuit50is added and the terminal failure detection processing is executed.

Since the terminal state detection circuit50of the ninth embodiment is the same as the terminal state detection circuit50according to the eighth embodiment, the description thereof will be omitted.

As illustrated inFIGS.21and24, a first row C1and a second row C2inFIG.24are the same as the first row C1and the second row C2inFIG.21, respectively. A fourth row C4and a fifth row C5inFIG.24are the same as the third row C3and the fourth row C4inFIG.21, respectively. A seventh row C7and an eighth row C8inFIG.24are the same as the fifth row C5and the sixth row C6inFIG.21, respectively. A tenth row C10and an eleventh row C11inFIG.24are the same as the seventh row C7and the eighth row C8inFIG.21, respectively. Therefore, 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 C11inFIG.24are omitted.

As illustrated in the third row C3inFIG.24, when the switching element14is switched from the on state to the off state in a case where the ECU1and the electromagnetic valve2are normal, the electromagnetic valve2is switched to the off state. Thus, a current flows through the shunt resistor15only for a short time, and the voltage level of the negative terminal12turns from the low level to the high level. Therefore, the current detection signal output from current detection circuit16changes from the low level to the high level only for a short time, and returns to the low level again. The terminal state detection signal output from the terminal state detection circuit50changes from the low level to the high level.

As illustrated in the sixth row C6inFIG.24, when the switching element14is switched from the on state to the off state in a state where a battery short-circuit failure occurs, the electromagnetic valve2remains in the off state. At this time, as in the normal time, a current flows through the shunt resistor15only for a short time, and the voltage level of the negative terminal12turns from the low level to the high level. Therefore, the current detection signal output from current detection circuit16changes from the low level to the high level only for a short time, and returns to the low level again. The terminal state detection signal output from the terminal state detection circuit50changes from the low level to the high level.

As illustrated in the ninth row C9inFIG.24, when the switching element14is switched from the on state to the off state in a case where a ground short-circuit failure occurs, the electromagnetic valve2remains in the on state. At this time, no current flows through the shunt resistor15, and the voltage level of the negative terminal12remains in the low level. Thus, the current detection circuit16outputs a current detection signal for the voltage level to be the low level. The terminal state detection circuit50outputs a terminal state detection signal for the voltage level to be the low level.

As illustrated in a twelfth row C12inFIG.24, when the switching element14is switched from the on state to the off state in a state where an open failure occurs, the electromagnetic valve2remains in the off state. At this time, no current flows through the shunt resistor15, and the voltage level of the negative terminal12turns from the low level to the high level. Thus, the current detection signal output from the current detection circuit16remains in the low level. The terminal state detection signal output from the terminal state detection circuit50changes from the low level to the high level.

Next, a procedure of the terminal failure detection processing executed by the CPU21of the microcomputer19will be described.

As illustrated inFIG.25, the terminal failure detection processing according to the ninth embodiment is different from the terminal failure detection processing according to the eighth embodiment in that the processing of S650is omitted and the processing of S660and S670are added.

That is, when the processing of S640ends, the CPU21determines in S660whether the switching element14is in the off state, Here, when the switching element14is not in the off state, the processing of S660is repeated to stand by until the switching element14is in the off state.

When the switching element14enters the off state, the CPU21detects an open failure in S670, and ends the terminal failure detection processing. Specifically, the CPU21determines whether a current flows through the shunt resistor15on the basis of the current detection signal. Here, when no current flows through the shunt resistor15, the CPU21sets the open failure flag F13. On the other hand, when a current flows through the shunt resistor15, the CPU21clears the open failure flag F13.

The ECU1configured as described above includes the positive terminal11, the negative terminal12, and the terminal state detection circuit50.

The microcomputer19detects a ground short-circuit failure in the negative terminal12on the basis of a detection result of the terminal state detection circuit50when the application of the power supply voltage to the electromagnetic valve2is stopped.

The microcomputer19detects a battery short-circuit failure in the negative terminal12on the basis of the detection result of the terminal state detection circuit50while power is supplied to the electromagnetic valve2.

The microcomputer19detects an open failure in the negative terminal12on the basis of the detection result of the terminal state detection circuit50immediately after the application of the power supply voltage to the electromagnetic valve2is stopped.

The ECU1as described above enables to detect a ground short-circuit failure, a battery short-circuit failure, and an open failure at the negative terminal12.

In the embodiment described above, S670corresponds to processing as a second open failure detector.

Although one embodiment of the present disclosure has been described above, the present disclosure is not limited to the embodiment, and various modifications can be made.

First Modification

For example, the above embodiment has shown a mode in which a point at which the electromagnetic valve current value changes from decrease to increase in the temporal change of the electromagnetic valve current is detected as an electromagnetic valve current singularity. However, the electromagnetic valve current singularity may be any point as long as a transition between the closed valve state and the open valve state in the electromagnetic valve2can be identified. For example, the electromagnetic valve current singularity may be a point at which the electromagnetic valve current value changes from increase to decrease, or may be a point at which a decrease gradient changes rapidly.

Second Modification

The above embodiment has shown a mode in which a point at which the regenerative current value changes from increase to decrease in the temporal change of the regenerative current is detected as a regenerative current singularity. However, the regenerative current singularity may be any point as long as a transition between the closed valve state and the open valve state in the electromagnetic valve2can be identified. For example, the regenerative current singularity may be a point at which the regenerative current value changes from decrease to increase, or may be a point at which an increase gradient changes rapidly.

The microcomputer19and a method thereof described in the present disclosure may be achieved by a dedicated computer provided by configuring a processor and a memory programmed to execute one or a plurality of functions embodied by a computer program. Alternatively, the microcomputer19and the method thereof described in the present disclosure may be achieved by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the microcomputer19and the method thereof described in the present disclosure may be achieved by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or a plurality of functions and a processor configured by one or more hardware logic circuits.

The computer program may be stored in a computer-readable non-transitory tangible recording medium as an instruction executed by a computer. The method of achieving functions of parts included in the microcomputer19does not need to include software, and all the functions may be achieved by using one or a plurality of pieces of hardware.

A plurality of functions of one component in the embodiment may be achieved by a plurality of components, or one function of one component may be achieved by a plurality of components. A plurality of functions of a plurality of components may be achieved by one component, or one function achieved by a plurality of components may be achieved by one component. A part of the configuration of the embodiment may be omitted. At least a part of the configuration of the embodiment may be added to or replaced with another configuration of the embodiment.

In addition to the ECU1described above, the present disclosure can be achieved in various forms such as a system including the ECU1as a component, a program for causing a computer to function as the ECU1, a non-transitory tangible recording medium such as a semiconductor memory storing the program, and a failure detection method.