Control for vehicle temperature conditioning system

A control for a temperature conditioning system including a vapor compression air conditioner and a heater for use in a vehicle, said control comprising

• (a) a discharge air temperature sensor, disposed downstream of the heater, for sensing the temperature of air discharged from the system into the interior of the vehicle;
• (b) a return air temperature sensor;
• and
• (c) control means responsive to the discharge air temperature sensor and return air temperature sensor and operative to activate the heater in a reheat mode to heat air cooled by the air conditioner, if the return air temperature decreases to less than a predetermined value and the discharge air temperature decreases to less than a setpoint value;
• and further operative to de-activate the heater to terminate the reheat mode when the discharge temperature increases above the setpoint value, whereby temperature overshoot in the interior of the vehicle resulting from thermal inertia of the heater is minimized.

A control for a system in which a vapor compression air conditioner and a heater are used to temperature condition air circulated through the interior of a vehicle, said control comprising

• (a) an outside ambient air temperature sensor;
• (b) a discharge air temperature sensor, disposed downstream of the heater, for sensing the temperature of air discharged from the system into the interior of the vehicle;
• (c) a return air temperature sensor;
• and
• (d) control means, responsive to the outside ambient, discharge, and return air temperature sensors and operative to energize the vapor compression air conditioner to cool the air circulated through the interior of the vehicle, if both
• (i) the return air temperature exceeds a predetermined maximum value, and
• (ii) the outside ambient air temperature exceeds a predetermined limit;
• and thereafter, while the air conditioner is in operation, the control means are further operative to activate the heater to reheat the cooled air;
• if both
• (a) the return air temperature decreases to less than the predetermined maximum value and
• (b) the discharge air temperature is less than a setpoint value;
• and to de-activate the heater;
• when the discharge temperature exceeds the setpoint value.

A method for controlling a temperature conditioning system including a vapor compression air conditioner and a heater for use in a vehicle, said method comprising the steps of

• (a) sensing the temperature of air discharged from the system into the interior of the vehicle, at a point downstream of the heater;
• (b) sensing the temperature conditioning demand in the interior of the vehicle;
• and
• (c) activating the heater in a reheat mode to heat air cooled by the air conditioner, said reheat mode being activated in response to the temperature conditioning demand;
• and further, de-activating the heater to terminate the reheat mode if the discharge air temperature increases above a setpoint value, whereby the temperature conditioning demand in the interior of the vehicle is satisfied without excessive reheat overshoot resulting from the thermal inertia of the heater.

A method for controlling a temperature conditioning sytem including a vapor compression air conditioner and a heater for use in a vehicle, said method comprising the steps of:

• (a) sensing the temperature of air discharged from the system into the interior of the vehicle, at a point downstream of the heater;
• (b) sensing the return air temperature;
• and
• (c) activating the heater in a reheat mode to heat air cooled by the air conditioner, if the return air temperature decreases to less than a predetermined value and the discharge air temperature decreases to less than a setpoint value;
• and further, de-activating the heater to terminate the reheat mode when the discharge temperature increases above the setpoint value, whereby temperature overshoot in the interior of the vehicle resulting from thermal inertia of the heater is minimized.

A method for controlling a system in which a vapor compression air conditioner and a heater are used to temperature condition air circulated through the interior of a vehicle, said method comprising the steps of

• (a) sensing the outside ambient air temperature;
• (b) sensing the temperature of air discharged from the system into the interior of the vehicle, at a point downstream of the heater;
• (c) sensing the return air temperature;
• and
• (d) energizing the vapor compression air conditioner to cool the air circulated through the interior of the vehicle, if both
• (i) the return air temperature exceeds a predetermined maximum value, and
• (ii) the outside ambient air temperature exceeds a predetermined limit;
• and thereafter, while the air conditioner is in operation, activating the heater to reheat the cooled air, if both
• (a) the return air temperature decreases to less than the predetermined maximum value, and
• (b) the discharge air temperature is less than a setpoint value;
• and de-activating the heater, if the discharge temperature increases to exceed the setpoint value.