Solenoid drive device

1. A solenoid drive device comprising:

a first solenoid drive circuit including a first solenoid, a first switching element configured to perform duty control of an application voltage of the first solenoid, and a first current detection element configured to detect a first drive current supplied to the first solenoid;

a second solenoid drive circuit including a second solenoid, a second switching element configured to perform duty control of an application voltage of the second solenoid, and a second current detection element configured to detect a second drive current supplied to the second solenoid; and

a control element configured to change the first drive current and the second drive current by performing on/off duty control of the first switching element and the second switching element,

wherein the solenoid drive device includes a selection circuit configured to select either one of a first current detection signal outputted from the first current detection element and a second current detection signal outputted from the second current detection element,

wherein the control element comprises:

a duty control element configured to supply a selection command signal selecting either one of the first current detection signal and the second current detection signal to the selection circuit, acquire values of the first drive current and the second drive current based on a selection detection signal outputted from the selection circuit, and perform the on/off duty control depending on the acquired values of the first drive current and the second drive current; and

a failure determination element configured to perform failure determination with the selection circuit, the first solenoid drive circuit, and the second solenoid drive circuit as determination targets based on change characteristics of the selection detection signal,

wherein the duty control element performs the on/off duty control of the first switching element in the same control cycle as on/off duty control of the second switching element, and sets on/off switching direction of the first switching element at a start time of one control cycle and on/off switching direction of the second switching element reversely from each other, the on/off switching direction including a switching direction from on to off and a switching direction from off to on, and

wherein the failure determination element performs the failure determination based on change characteristics of the selection detection signal in a specified period when on/off states of the first switching element and the second switching element are different from each other.

2. The solenoid drive device according to claim 1 ,

wherein when the selection detection signal changes in a first direction within the specified period in a state where a selection command signal selecting one out of the first current detection signal and the second current detection signal is outputted,

the failure determination element:

determines that the determination target is normal when the selection detection signal changes in a second direction reverse to the first direction within the specified period in a state where a selection command signal selecting the other one out of the first current detection signal and the second current detection signal is outputted; and

determines that the selection circuit sticks to the one when the selection detection signal changes in the first direction.

3. The solenoid drive device according to claim 1 ,

wherein when the selection detection signal changes in a first direction within the specified period in a state where a selection command signal selecting one out of the first current detection signal and the second current detection signal is outputted,

the failure determination element determines that there is a failure with a solenoid drive circuit corresponding to the other current detection signal when there is no change of the selection detection signal in a state where a selection command signal selecting the other one out of the first current detection signal and the second current detection signal is outputted.

4. A solenoid drive device comprising:

a first solenoid drive circuit comprising:

a first solenoid;

a first switching element to control a first application voltage applied to the first solenoid; and

a first current detection element to detect a first drive current supplied to the first solenoid and to output a first current detection signal;

a second solenoid drive circuit comprising:

a second solenoid;

a second switching element to control a second application voltage applied to the second solenoid; and

a second current detection element to detect a second drive current supplied to the second solenoid and to output a second current detection signal;

a selection circuit connected to the first current detection element and the second current detection element; and

circuitry configured to

output a selection command signal to the selection circuit to select either one of the first current detection signal and the second current detection signal so as to output a selection detection signal,

acquire values of the first drive current and the second drive current based on the selection detection signal, and

control the first switching element and the second switching element with a duty control to control the first drive current and the second drive current in a control cycle according to the acquired values of the first drive current and the second drive current so that a first on/off switching direction of the first switching element at a start timing of the control cycle is opposite to a second on/off switching direction of the second switching element at the start timing, the first on/off switching direction and the second on/off switching direction including a switching direction from on to off and a switching direction from off to on, and

determine whether a failure in at least one of the selector, the first solenoid drive circuit, and the second solenoid drive circuit occurs based on a change in the selection detection signal in a period during which an on/off state of the first switching element is different form an on/off state of the second switching element.

5. The solenoid drive device according to claim 4 ,

wherein when the selection detection signal changes in a first direction within the period in a state where the selection command signal selecting one out of the first current detection signal and the second current detection signal is outputted,

the circuitry is configured to

determine that a determination target in which the failure occurs is normal when the selection detection signal changes in a second direction reverse to the first direction within the period in a state where the selection command signal selecting the other one out of the first current detection signal and the second current detection signal is outputted; and

determine that the selection circuit sticks to the one when the selection detection signal changes in the first direction.

6. The solenoid drive device according to claim 4 ,

wherein when the selection detection signal changes in a first direction within the period in a state where the selection command signal selecting one out of the first current detection signal and the second current detection signal is outputted,

the circuitry is configured to determine that there is the failure in the first solenoid drive circuit or the second solenoid drive circuit corresponding to an another current detection signal when there is no change of the selection detection signal in a state where the selection command signal selecting the other one out of the first current detection signal and the second current detection signal is outputted.