Solenoid valve drive device

1. A solenoid valve drive device wherein a hysteresis set value or a hysteresis time is set based on a first difference value between an extreme value of a hysteresis value of a solenoid valve current in a peak hold section of the solenoid valve current and a hysteresis set value, the solenoid valve drive device comprising:

a controller configured to:

output an opening/closing command to a first switching element for turning on/off a drive current supplied to the solenoid valve,

generate a hysteresis of the drive current by repeatedly turning on/off the first switching element in a first peak hold period after a current value of the drive current reaches a first current level, and

(i) set extreme values of the hysteresis such that the hysteresis of the drive current falls within a predetermined range from the first current level, or (ii) set a time interval between extreme values of the hysteresis such that the hysteresis of the drive current falls within a predetermined range from the first current level; and

a storage device configured to store set values of the extreme values of the hysteresis and a set value of the time interval between the extreme values of the hysteresis,

wherein the controller is further configured to:

calculate a first gradient of the hysteresis of the drive current using the extreme values of the hysteresis of the drive current and the time interval between the extreme values and calculate a second gradient of the hysteresis using the set values of the extreme values of the hysteresis and the set value of the time interval between the extreme values of the hysteresis, and

set the extreme values of the hysteresis or set the time interval between the extreme values of the hysteresis so that a second difference value between the first gradient and the second gradient falls within a predetermined gradient threshold in a case where the second difference value is not within the predetermined gradient threshold.

2. The solenoid valve drive device according to claim 1 , wherein

the first switching element is configured to supply the drive current to the solenoid valve by supplying a battery voltage to the solenoid valve,

the controller is configured to:

maintain an opened state of the solenoid valve using the battery voltage by turning on/off the first switching element in the first peak hold period after the current value of the drive current reaches a second current level higher than the first current level, and

make a timing at which the solenoid valve transitions from the opened state to a closed state fall within an allowable time after instructing the first switching element to be turned off by making the hysteresis fall within a predetermined range from the first current level in the first peak hold period.

3. The solenoid valve drive device according to claim 1 , wherein

the controller is configured to output an opening/closing command to a second switching element for turning on/off a drive current supplied to the solenoid valve,

the second switching element is configured to open the solenoid valve by supplying a boosted voltage obtained by boosting a battery voltage to the solenoid valve to supply the drive current having a second current level higher than the first current level to the solenoid valve, and

the controller is configured to drive and control the second switching element so that an extreme value of the drive current falls within a predetermined range from the second current level.

4. The solenoid valve drive device according to claim 3 , wherein

the controller is configured to:

generate a hysteresis of the drive current by repeatedly turning on/off the second switching element in a second peak hold period after the current value of the drive current reaches the second current level, and

set extreme values of the hysteresis or set a time interval between the extreme values of the hysteresis so that the hysteresis of the drive current falls within a predetermined range from the second current level.

5. The solenoid valve drive device according to claim 3 , wherein

the controller is configured to:

turn off the second switching element and acquire a measured value of the extreme value of the drive current, when the current value of the drive current reaches the second current level, and

drive and control the second switching element according to the measured value of the extreme value of the drive current so that the extreme value of the drive current falls within a predetermined range from the second current level, when opening the solenoid valve by turning on the second switching element again after turning off the second switching element.

6. The solenoid valve drive device according to claim 1 , wherein

the controller is configured to:

acquire the first difference value between the extreme value of the hysteresis and a set value of the extreme value of the hysteresis by acquiring a difference between a measured value of the drive current and a set value of the drive current, and

repeat the acquisition of the first difference value and repeat the setting of the extreme values of the hysteresis or the setting of the time interval between the extreme values of the hysteresis, until the first difference value becomes equal to or less than a predetermined threshold.

7. The solenoid valve drive device according to claim 1 , wherein

the controller is configured to:

acquire the first difference value between the extreme value of the hysteresis and a set value of the extreme value of the hysteresis by acquiring a difference between a measured value of the drive current and a set value of the drive current, and

repeat the acquisition of the first difference value and repeat the setting of the extreme values of the hysteresis or the setting of the time interval between the extreme values of the hysteresis, while the solenoid valve drive device is activated.

8. The solenoid valve drive device according to claim 1 , wherein

the controller is configured to:

acquire the first difference value between the extreme value of the hysteresis and a set value of the extreme value of the hysteresis by acquiring a difference between a measured value of the drive current and a set value of the drive current, and

repeat the acquisition of the first difference value a predetermined number of times and repeat the setting of the extreme values of the hysteresis or the setting of the time interval between the extreme values of the hysteresis a predetermined number of times.

9. The solenoid valve drive device according to claim 1 , wherein

the controller is configured to:

acquire a first extreme value in the hysteresis of the drive current, and

set the extreme values of the hysteresis or set the time interval between the extreme values of the hysteresis so that a second extreme value in the same hysteresis of the drive current falls within the predetermined range, in a case where the first extreme value does not fall within the predetermined range.

10. The solenoid valve drive device according to claim 1 , wherein the controller is configured to calculate an average value or an execution value of the extreme values of the hysteresis from a first time to a second time, and calculate a difference between the calculated value and the hysteresis set value as the first difference value.