Temperature adjustment apparatus and method of controlling Peltier element

1. A temperature adjustment apparatus comprising:

a Peltier element supplied with electric power to allow heat exchange between an electronic device mounted on a vehicle and a heat exchange portion of the vehicle;

a Peltier element temperature sensor that detects a temperature of a first surface of the Peltier element serving as an exothermic surface and a temperature of a second surface of the Peltier element serving as an endothermic surface;

an electronic control unit operatively connected to the Peltier element and the Peltier element temperatures sensor, the electronic control unit configured to:

control the electric power supplied to the Peltier element;

obtain information on a temperature of air outside the electronic device;

store drive condition information in which the temperature of air outside the electronic device, an electric power supplied to the Peltier element and a supply time period during which electric power is supplied are associated with each other;

determine the electric power continuously supplied to the Peltier element during a continuous energization based on the temperature of air outside the electronic device; and

determine the electric power and the supply time period during an intermittent energization based on the electric power during the continuous energization, the intermittent energization being a state in which a deenergizing state and an energizing state are alternately occurred, the deenergizing state being a state in which no electric power is supplied to the Peltier element, the energizing state being a state in which electric power is supplied to the Peltier element,

wherein the electronic control unit executes, according to a determination made by the electronic control unit, temperature maintenance control in which the deenergizing state is occurred when the temperature difference between the first surface of the Peltier element and the second surface of the Peltier element becomes larger than a first predetermined value as a result of supply of electric power to the Peltier element, and the energizing state is restarted when the temperature difference between the first and second surfaces is reduced to a second predetermined value smaller than the first predetermined value after supply of electric power to the Peltier element is stopped,

wherein the electronic control unit executes the continuous energization until the temperature of the electronic device reaches a target temperature and the electronic control unit executes the intermittent energization after the temperature of the electronic device reaches the target temperature.

2. The temperature adjustment apparatus according to claim 1 , wherein the temperature of the electronic device is repeatedly increased and reduced between the target temperature and a lower limit temperature lower than the target temperature in the temperature maintenance control, and

wherein a COP (coefficient of performance) of the Peltier element during the temperature maintenance control is higher than a COP (coefficient of performance) of the Peltier element when the temperature of the electronic device is maintained at a fixed temperature corresponding to an intermediate temperature between the target temperature and the lower limit temperature by continuously supplying constant electric power to the Peltier element.

3. The temperature adjustment apparatus according to claim 2 , further comprising a case in which the electronic device is housed,

wherein the information on the temperature of air outside the electronic device is acquired from a sensor provided on an external surface of the case;

the heat exchange portion includes part of the case and extends to a position inside a duct provided on the vehicle, air being passed through the duct; and

the Peltier element is in contact with the electronic device and with the heat exchange portion.

4. The temperature adjustment apparatus according to claim 1 , further comprising a case in which the electronic device is housed,

wherein the information on the temperature of air outside the electronic device is acquired from a sensor provided on an external surface of the case;

the heat exchange portion includes part of the case and extends to a position inside a duct provided on the vehicle, air being passed through the duct; and

the Peltier element is in contact with the electronic device and with the heat exchange portion.