Heating systems – Heat and power plants – Vehicle
Reexamination Certificate
2000-12-04
2001-12-18
Joyce, Harold (Department: 3749)
Heating systems
Heat and power plants
Vehicle
C237S01230B, C165S042000
Reexamination Certificate
active
06330979
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application is related to and claims priority from Japanese Patent Applications No. Hei. 11-357994 filed on Dec. 16, 1999 and No. 2000-172107 filed on Jun. 8, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vehicle air conditioner which automatically determines a windshield-fogging condition and automatically selects a foot/defroster mode to prevent a windshield from being fogged during heating operation in winter.
2. Description of Related Art
In a conventional automatic control type air conditioner for a vehicle, generally, heating operation for a passenger compartment is started from a foot mode in winter. During the foot mode, a large amount of air to be blown into the passenger compartment (e.g., about 70 to 80%) is blown toward the foot area of a passenger in the passenger compartment from a foot outlet, and a small amount of air is blown toward a windshield from a defroster outlet.
At a cold time when outside air temperature decreases to 0° C. or lower, if only a small amount of air (warm air) is blown toward the windshield from the defroster outlet, the temperature of the windshield is not sufficiently increased, and the inner surface of the windshield is readily fogged. Accordingly, a driver (passenger) manually switches an air-blowing mode to a foot/defroster mode or a defroster mode to defrost the windshield.
In this case, whenever the windshield is fogged, it is necessary for the driver to manually set the foot/defroster mode or the defroster mode, and the manual operation annoys the driver.
U.S. Pat. No. 5,137,213 discloses a vehicle air conditioner for improving both defrosting performance for a windshield and heating performance for a passenger compartment. That is, a first defroster/foot mode corresponding to the foot mode and a second defroster/foot mode corresponding to the foot/defroster mode are set as a defroster/foot mode where air is blown toward the inner surface of the windshield from the defroster outlet while air is blown to the foot area (lower side) from the foot outlet. In the first defroster/foot mode, an amount of air blown from the defroster outlet is made smaller. In the second defroster/foot mode, the amount of air blown from the defroster outlet is made larger than that during the first defroster/foot mode. When the outside air temperature is low, the windshield is prevented from being fogged by setting the second defroster/foot mode. When a target temperature of air blown into the passenger compartment is set higher than a predetermined temperature, the air-blowing mode is switched to the first defroster/foot mode while air-blowing amount is increased in accordance with an increase of the target temperature.
However, since the air-blowing mode is switched between the first defroster/foot mode and the second defroster/foot mode) according to only the conditions of the target temperature of air blown into the passenger compartment and the outside air temperature, a windshield-fogging condition cannot be accurately determined, and the windshield may be fogged.
On the other hand, if a setting range of the foot/defroster mode is simply enlarged in order to improve the fog-preventing performance of the windshield, a setting range of the foot mode is relatively reduced, thereby deteriorating the heating performance of the passenger compartment.
SUMMARY OF THE INVENTION
In view of the foregoing problems, it is an object of the present invention to provide a vehicle air conditioner that improves both of fog-preventing performance of a windshield and heating performance of a passenger compartment by suitably selecting a foot/defroster mode based on a windshield-fogging condition.
According to the present invention, in a vehicle air conditioner which can set a foot mode and a foot/defroster mode, a control unit sets the foot mode when a target temperature of air blown into a passenger compartment is higher than or equal to a predetermine target value. The control unit selects the foot/defroster mode in place of the foot mode, when at least one of a first condition where a vehicle speed is higher than or equal to a predetermined speed and a second condition where a sunlight amount entering into the passenger compartment is lower than or equal to a predetermined amount is satisfied. Therefore, a windshield-fogging condition can be suitably determined based on at least the vehicle speed and the sunlight amount, and the foot/defroster mode can be automatically set based on the windshield-fogging condition. Accordingly, the fog-preventing performance of the windshield can be improved without a manual operation of a driver. Further, when the windshield-fogging condition is not determined, the foot mode is always set in a heating operation, so that heating performance in the passenger compartment is improved.
Preferably, the foot/defroster mode is selected in place of the foot mode, when a third condition where an outside air temperature is lower than or equal to a predetermined outside temperature is further satisfied in addition to the first and second conditions. Therefore, the windshield-fogging condition can be accurately determined.
Alternatively, the control unit selects the foot/defroster mode in place of the foot mode, when a temperature of the windshield is lower than a predetermined temperature. The temperature of the windshield can be estimated based on parameters relating to the temperature of the windshield. For example, the parameters are the outside air temperature and the vehicle speed, the outside air temperature and the sunlight amount, three the outside air temperature, the vehicle speed and the sunlight amount, or the like. In addition, the temperature of the windshield can be directly detected using a temperature sensor.
Preferably, the control unit includes a foot mode selection portion for selecting the foot mode when a target temperature of air blown into the passenger compartment is larger than a predetermined target value, a determining portion for determining a warm-up control or a stationary heating control, and a foot/defroster mode selection portion for selecting the foot/defroster mode in place of the foot mode. When the determining portion determines the warm-up control, the foot/defroster mode selection portion selects the foot/defroster mode when the outside air temperature is lower than a predetermined temperature and when the sunlight amount entering into the passenger compartment is lower than a predetermined amount. On the other hand, when the determining portion determines the stationary heating control, the foot/defroster mode selection portion selects the foot/defroster mode when the outside air temperature is lower than a predetermined temperature and when the vehicle speed is higher than a predetermined speed. Accordingly, during the warm-up control or the stationary heating control, the windshield-fogging condition can be accurately determined, and the foot mode and the foot/defroster mode can be automatically selectively set in accordance with a vehicle condition.
REFERENCES:
patent: 5137213 (1992-08-01), Yamamoto et al.
patent: 5566881 (1996-10-01), Inoue et al.
patent: 5794845 (1998-08-01), Ito et al.
patent: 5884839 (1999-03-01), Aoki et al.
patent: 5931380 (1999-08-01), Aoki et al.
Hotta Hiroyuki
Kamei Seiji
Umebayashi Makoto
Uramune Hidekazu
Yamashita Kouji
Boles Derek
Denso Corporation
Harness Dickey & Pierce PLC
Joyce Harold
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