Control method for thermo-electric heating of a vehicle seat
Conditioned air discharged from a vehicle heating, ventilation and air conditioning (HVAC) unit is further conditioned by a thermoelectric (TE) air temperature control module and then directed to air passages in a vehicle seat. Activation of the TE air temperature control module is based on climate control parameters utilized by the HVAC unit, including the set temperature and the cabin air temperature.
This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/329,711, filed on Jan. 10, 2006, and assigned to the assignee of the present invention.
FIELD OF THE INVENTIONThe present invention relates to thermoelectric temperature regulation of a vehicle seat, and more particularly to a method of controlling seat heating.
BACKGROUND OF THE INVENTIONOccupant comfort in a motor vehicle can be effectively addressed by controlling the temperature of the cabin air and by regulating the temperature of seating surfaces. Various mechanisms for achieving both cabin air and seat temperature control are well known in the art. See, for example, the U.S. Pat. Nos. 5,918,930 and RE38,128 in respect to seat temperature control. In U.S. Pat. No. 5,918,930, thermally conditioned air ordinarily discharged from the vehicle's heating, ventilation and air conditioning (HVAC) system is routed through passages in the vehicle seats; and in U.S. Pat. No. RE38,128, air handling modules including Peltier thermoelectric (TE) devices draw cabin air over the TE units and deliver the heated or cooled cabin air to passages in the vehicle seats. However, a more effective approach is to install a TE module in series between the HVAC system and the vehicle seat passages. This dramatically improves the transient thermal regulation of the seats, providing significantly faster cool-down when the HVAC system is in a cooling mode and significantly faster warm-up when the HVAC system is in a heating mode. In any event, the present invention is directed to a heating mode control strategy for a TE unit configured to supply conditioned air to air passages of a vehicle seat.
SUMMARY OF THE INVENTIONThe present invention provides an improved method of operation for a heated vehicle seat in which a TE air temperature control module supplies conditioned air to air passages in the seat. Preferably, air discharged from the vehicle HVAC unit is further conditioned by the TE air temperature control module and then directed to the air passages in the seat. Activation of the TE air temperature control module is based on climate control parameters utilized by the HVAC unit, including the set temperature and the cabin air temperature.
Referring to
Referring to
In operation, the HVAC unit 28 selectively activates the TE device 42 to further heat or chill the air flowing through heat exchanger 44 to provide optimal occupant comfort. In the illustrated embodiment, the control of TE device 42 is implemented by a microcontroller (uC) 28a resident within a control head of HVAC unit 28. Referring to
The present invention is directed to a control method carried out by the microcontroller 28a during the HVAC heating mode when HVAC unit 28 supplies heated air to the cabin and seat ducts 30, 32 in order to satisfy the occupant set temperature Tset. Referring to
The target seat temperature Ttar is determined based on thermal comfort considerations for any combination of cabin temperature Tcabin and set temperature Tset. The fundamental constraints on Ttar are determined for a nominal set temperature Tset such as 25° C., and include a first schedule (referred to herein as Ttar_cold) for cold cabin temperatures (say, 10° C. or less) and a second schedule (referred to herein as Ttar_warm) for warm cabin temperatures (say, 35° C. or more). The schedules Ttar_cold and Ttar_warm are of the form:
Ttar_cold=(K1*Tcabin3)+(K2*Tcabin2)+(K3*Tcabin)+K4, and
Ttar_warm=(K1*Tcabin3)+(K2*Tcabin2)+(K3*Tcabin)+K5
where K1-K3 are calibrated coefficients, and K4 and K5 are calibrated offsets. By way of example, the offset K5 may be 4.4° C. less than the offset K4. For intermediate cabin temperatures, the target seat temperature Ttar is linearly interpolated between the first and second schedules. This is graphically depicted in
In operation, microprocessor 28a periodically updates the target seat temperature Ttar based on Tcabin and Tset, and activates TE device 42 of TE air temperature control module 36 as generally described above in reference to
The block 102 determines the current mode (heating or cooling) of the TE device 42. Initially, the TE device will be configured for heating due to the operation of block 92; in this case, block 102 is answered in the affirmative, and the blocks 104-116 of
If the mode of TE device 42 is changed to cooling as described above, the block 102 of
In summary, the present invention provides an easily implemented control method for supplemental thermoelectric heating of a vehicle seat. The control method accounts for changes in the cabin and set temperatures, and achieves a desired occupant comfort level without requiring extensive calibration effort. While the present invention has been described with respect to the illustrated embodiment, it is recognized that numerous modifications and variations in addition to those mentioned herein will occur to those skilled in the art. For example, the disclosed control method could be used in a system where the HVAC discharge air or even cabin air is drawn through the TE air temperature control module 36 by an auxiliary fan, and so on. Accordingly, it is intended that the invention not be limited to the disclosed embodiment, but that it have the full scope permitted by the language of the following claims.
Claims
1. A method of operation for a thermoelectric air temperature control module that delivers conditioned air to a passenger seat of a vehicle, where the vehicle additionally includes a heating, ventilation and air conditioning (HVAC) unit, the method comprising the steps of:
- measuring a temperature of air in a cabin of said vehicle;
- determining a target seat temperature during a heating mode of said HVAC unit based on a set temperature of said HVAC unit and the measured cabin air temperature;
- measuring a temperature of said seat; and
- controlling an operating mode and an activation level of said thermoelectric air temperature control module to bring the measured seat temperature into conformance with said target seat temperature.
2. The method of claim 1, including the steps of:
- decreasing the activation level of said thermoelectric air temperature control module to provide less seat heating when the operating mode of said thermoelectric air temperature control module is heating and said measured seat temperature is above the target seat temperature by at least a calibrated value;
- increasing the activation level of said thermoelectric air temperature control module to provide more seat heating when the operating mode of said thermoelectric air temperature control module is heating and said measured seat temperature is below the target seat temperature by at least said calibrated value; and
- changing the operating mode of said thermoelectric air temperature control module from heating to cooling when said measured seat temperature is above the target seat temperature by at least said calibrated value and the activation level of said thermoelectric air temperature control module has been decreased to a minimum level.
3. The method of claim 2, including the steps of:
- increasing the activation level of said thermoelectric air temperature control module to provide more seat cooling when the operating mode of said thermoelectric air temperature control module is cooling and said measured seat temperature is above the target seat temperature by at least said calibrated value;
- decreasing the activation level of said thermoelectric air temperature control module to provide less seat cooling when the operating mode of said thermoelectric air temperature control module is cooling and said measured seat temperature is below the target seat temperature by at least a calibrated value; and
- changing the operating mode of said thermoelectric air temperature control module from cooling to heating when said measured seat temperature is below the target seat temperature by at least said calibrated value and the activation level of said thermoelectric air temperature control module has been decreased to the minimum level.
4. The method of claim 1, including the steps of:
- controlling said thermoelectric air temperature control module to provide maximum heating of the air delivered to said passenger seat upon initial activation of said HVAC unit in said heating mode.
5. The method of claim 1, where the step of determining the target seat temperature includes the steps of:
- determining a first target seat temperature based on the measured cabin air temperature using a schedule derived for cabin temperatures greater than a calibrated upper temperature; and
- adjusting said first target seat temperature upward based on a deviation of the measured cabin air temperature below said calibrated upper temperature to form said target seat temperature.
6. The method of claim 1, where the step of determining the target seat temperature includes the steps of:
- determining a nominal target seat temperature based on the measured cabin air temperature, using a schedule derived for a nominal value of said set temperature; and
- adjusting said nominal target seat temperature up or down based on a deviation of said set temperature above or below said nominal value to form said target seat temperature.
7. The method of claim 1, including the step of:
- limiting the determined target seat temperature to a calibrated maximum value.
Type: Application
Filed: Jan 4, 2007
Publication Date: Jul 12, 2007
Inventors: Lin Jie Huang (East Amherst, NY), Edward I. Wolfe (Amherst, NY), Prasad S. Kadle (Williamsville, NY), Xiaoxia Mu (East Amherst, NY)
Application Number: 11/649,682
International Classification: F25B 21/02 (20060101); F25D 23/12 (20060101);