Controller and control method for linear solenoid valve

A controller for a linear solenoid valve, the controller comprising circuitry configured to execute:

• a pulse-width-modulation control that controls an exciting current in the linear solenoid valve supplied with hydraulic oil;
• and
• a dither control that cyclically increases and decreases the exciting current so as to vibrate a spool of the linear solenoid valve, wherein
• a vibration cycle of the spool obtained through the dither control,
• the dither control includes a first dither control that vibrates the spool in a first dither cycle and a second dither control that vibrates the spool in a second dither cycle that is shorter than the first dither cycle, pulse cycles of a pulse-width-modulation signal generated through the pulse-width-modulation control being pulse-width-modulation cycles, consecutive ones of the pulse-width-modulation cycles corresponding to the second dither cycle, and
• the circuitry is configured to execute the first dither control and the second dither control when an oil temperature of the hydraulic oil is between a first oil temperature and a second oil temperature that is higher than the first oil temperature.

A method for controlling a linear solenoid valve, the method comprising:

• executing a pulse-width-modulation control that controls an exciting current in the linear solenoid valve supplied with hydraulic oil;
• executing a dither control that cyclically increases and decreases the exciting current so as to vibrate a spool of the linear solenoid valve, wherein a vibration cycle of the spool obtained through the dither control, the dither control includes a first dither control that vibrates the spool in a first dither cycle and a second dither control that vibrates the spool in a second dither cycle that is shorter than the first dither cycle, pulse cycles of a pulse-width-modulation signal generated through the pulse-width-modulation control being pulse-width-modulation cycles, consecutive ones of the pulse-width-modulation cycles corresponding to the second dither cycle;
• and
• executing the first dither control and the second dither control when an oil temperature of the hydraulic oil is between a first oil temperature and a second oil temperature that is higher than the first oil temperature.