Automatic temperature and humidity regulation – Ventilator type – Electrically actuated
Reexamination Certificate
2001-07-19
2002-08-27
Tapolcai, William E. (Department: 3744)
Automatic temperature and humidity regulation
Ventilator type
Electrically actuated
C236S09100C
Reexamination Certificate
active
06439468
ABSTRACT:
TECHNICAL FIELD
It has been found that thermal comfort for an occupant in a vehicle is improved significantly when the air temperature is measured at the occupant's breath-level. The present invention is directed to a control system that works in conjunction with an automatic climate control system to measure air temperature at or adjacent to a vehicle occupant's breath-level and outputs a signal to the climate control system in order to improve the thermal comfort for the occupant. The present invention uses ultrasonic transducers to generate and receive acoustic waves that are propagated along a pre-selected path that passes adjacent to the vehicle occupant's breath-level. The transmission time of the acoustic waves is used to determine an average air temperature. The present invention correlates well with the temperature measured by a thermocouple in air at breath-level. This invention may also be used to measure air flows within the vehicle cabin.
BACKGROUND OF THE INVENTION
Automatic control of air temperature in a vehicle is made difficult both by the unpredictable nature of the cabin thermal environment and because people have different perceptions of thermal comfort. The factors that affect thermal comfort can be generally attributed to those environmental factors that affect body heat loss. In a vehicle interior, thermal comfort is mainly affected by the distribution of air temperature and air velocity around the occupant. Also important are the occupant's clothing, the amount of radiant heating and the humidity in the passenger cabin. A vehicle as used here refers to an automotive vehicle such as a car, bus, truck, van, sport utility vehicle, recreation vehicle, etc, or to an aircraft.
Several systems are presently used in vehicles for automatic climate control (ACC). Most current vehicles utilize an in-car sensor, located in the instrument panel near the base of the steering wheel, which draws air through a port from the vehicle's passenger cabin over a thermistor that measures the temperature of the air passing through the port. The sensor outputs the temperature to the vehicle's heating, ventilation and air conditioning (HVAC) system to control heating and cooling. Some vehicles also use multiple thermistors located at various points in the vehicle interior, and then average the temperature throughout the cabin.
In use, the ACC system has transient modes, such as warm-up and cool-down. During steady state operation, it tries to maintain the interior temperature at a desired set point. Present in-car temperature sensors, however, are prone to response-time lag and drift. This leads to control problems during some transient modes and even under steady state conditions.
More recently, some vehicles have begun using an infrared detector that measures the average surface temperature of persons or objects in a selected field of view based on a thermistor that measures air temperature and a thermopile detector that measures radiant flux from the field of view, such as, for example, disclosed in U.S. Pat. No. 5,518,176. Such systems, however, tend to be somewhat unreliable in accurately measuring air temperature because the temperature of a solid surface in a vehicle's interior changes slowly in response to changes in air temperature. Therefore, during a fast transient, the output from a sensor that measures the temperature of solids, such as an infrared detector, does not correlate well with the actual air temperature in the vehicle.
Models are known in the art for determining and controlling the temperature distribution inside a vehicle cabin using various inputs to the ACC controller. In addition to the in-car thermistor or infrared-based sensor, other inputs to current ACC systems include sensors of outside air temperature and sunlight exposure to the cabin, known as solar heat load. The desired temperature setting selected by each occupant is yet another input factor, or a default setting if none is selected by some occupants. Additional inputs include interior vehicle air flows, air vent discharge temperature, the thermal history of the vehicle, and the presence of occupants. The present invention may be used to replace the current in-car thermistor-based or infrared-based sensor and obtain a much improved measurement of bulk air temperature near or adjacent to the breath-level of one or more vehicle occupants. By accurately and rapidly measuring the average air temperature and average air velocity along a pre-selected path, the models known in the art can be used to find the temperature distribution in a vehicle cabin more accurately and more quickly than is currently done with the in-car sensor. It has been surprisingly found, however, that thermal comfort of a vehicle's occupant correlates very well with the temperature measured by a thermocouple, hanging in the air, positioned at breath-level in front of that occupant. It has further been found that the breath-level measurement is substantially better than the measurement of air temperature using in-car sensors or infrared temperature detectors known in the art.
SUMMARY OF THE INVENTION
The present invention is directed to an acoustic HVAC control system that determines the average air temperature along a pre-selected path to provide more accurate and timely climate control of a vehicle interior. It has been found that existing temperature measurement provides a poor correlation to thermal comfort of an occupant and that the correlation is much better when the temperature is measured at breath-level in front of the occupant's (such as the driver's) face. However, until the present invention, temperature measurement at such a location has not been feasible.
The present invention finds good agreement between breath-level temperature and the average air temperature along a pre-selected path even when the path is adjacent to the occupant and not directly in front of the occupant's face. For example, good agreement is found when the path is along the occupant side of the roof console that is mounted on the headliner near the occupant. Good agreement is also found when the path is along the top of the instrument panel or between the “A” pillar near a front seat occupant and the rear view mirror. Further, the path could be along the side of the occupant's seat or headrest, a rear view mirror, on the headliner above the occupant or from one part of the instrument panel to another. For the particular case of the vehicle's driver, the path is preferably from one part of the steering wheel or steering column to the another or to the instrument panel. For an occupant of a rear seat, the acoustic path is preferably from one part of the seat-back in front of the occupant to another (e.g., top-to-bottom or side-to-side). For an occupant of an aircraft seated in a seat on one side of the aircraft (that is, a window seat), the acoustic path is preferably parallel to and near that side of the aircraft. Thus, the exact location of the path adjacent to the occupant or to the occupant's breath-level is less important in that the path averages the air temperature near or adjacent to the occupant's breath-level, thus measuring the local average air temperature and not just an average temperature of the air in the entire vehicle. This local measurement can then be repeated if desired for other locations in the vehicle to facilitate zone control by the ACC system to improve thermal comfort for occupants in those locations.
It is however important that most of the path of the acoustic wave be spatially separated from the solid surfaces in the vehicle. This is because of the thermal boundary layer in the air near such surfaces. At such surfaces, the air velocity is zero and the air temperature is the same as the temperature of the solid. Outside of the boundary layer, which can for example be as much as 1 centimeter thick under some circumstances in the vehicle, turbulent flow tends to equalize the bulk air temperature. Thus, it is desirable to have the majority o
Han Taeyoung
Lambert David K.
Partin Dale Lee
Sultan Michel Farid
Delphi Technologies Inc.
Griffin Patrick M.
Tapolcai William E.
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