Vehicle-height control system

1. A vehicle-height control system configured to control a vehicle height for a wheel, the vehicle-height control system comprising:

a vehicle-height control actuator provided so as to correspond to the wheel;

a pressure-medium supply and discharge device configured to supply and discharge a pressure medium to and from the vehicle-height control actuator; and

a vehicle height controller configured to control the vehicle height for the wheel by controlling the pressure-medium supply and discharge device based on an inside temperature and an outside-air temperature to control at least one of supply and discharge of the pressure medium to and from the vehicle-height control actuator, the inside temperature being a temperature in the vehicle-height control system,

wherein the vehicle height controller is configured to determine, based on an operating state of an engine, whether the inside temperature is greater than the outside-air temperature by a set value.

2. The vehicle-height control system according to claim 1 , wherein the vehicle height controller is configured to control the pressure-medium supply and discharge device such that an actual value of the vehicle height for the wheel is brought closer to a target vehicle height, and the vehicle height controller comprises a target-vehicle-height determiner configured to determine the target vehicle height which is a target vehicle height in a case where a temperature difference is large, to a value greater than the target vehicle height which is a target vehicle height in a case where the temperature difference is small, and the temperature difference is a value obtained by subtracting the outside-air temperature from the inside temperature.

3. The vehicle-height control system according to claim 2 , wherein the target-vehicle-height determiner comprises a control-purpose-target-vehicle-height determiner configured to determine a control-purpose target vehicle height as the target vehicle height by adding a correction value determined based on the temperature difference, to a true target vehicle height determined based on a state of a vehicle.

4. The vehicle-height control system according to claim 3 , wherein the target-vehicle-height determiner comprises a correction value determiner configured to determine the correction value which is a value in a case where the temperature difference is large, to a value greater than the correction value which is a value in a case where the temperature difference is small.

5. The vehicle-height control system according to claim 1 , wherein the vehicle height controller comprises a down controller configured to lower the vehicle height for the wheel by controlling the pressure-medium supply and discharge device based on the inside temperature to control discharge of the pressure medium from the vehicle-height control actuator.

6. The vehicle-height control system according to claim 1 , wherein the vehicle height controller is configured to determine, based on the operating state of the engine and a vehicle speed, whether the inside temperature is greater than the outside-air temperature by the set value.

7. The vehicle-height control system according to claim 6 , wherein the vehicle height controller is configured to determine whether the inside temperature is greater than the outside-air temperature by the set value in a case where an engine rotation speed is greater than a set rotation speed, and a torque is greater than a set torque during running of the vehicle.

8. The vehicle-height control system according to claim 6 , wherein the vehicle height controller is configured to determine whether the inside temperature is greater than the outside-air temperature by the set value in a case where an idling duration is longer than a set length of time in a state in which the vehicle is stopped.