Heat exchange – With timer – programmer – time delay – or condition responsive... – Having heating and cooling capability
Reexamination Certificate
2001-04-27
2004-04-06
Ciric, L V (Department: 3753)
Heat exchange
With timer, programmer, time delay, or condition responsive...
Having heating and cooling capability
C165S042000, C165S043000, C165S223000, C165S231000, C165S240000, C237S00200B, C237S00200B
Reexamination Certificate
active
06715540
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present invention relates to an air-conditioning apparatus for heating the compartment within a vehicle with a hot water heating apparatus, and more particularly to an air conditioning apparatus that prevents window fogging due to re-evaporation of condensation water.
FIELD OF THE INVENTION
The present invention relates to an air-conditioning apparatus for heating the compartment within a vehicle through with a hot water heating apparatus, and more particularly to an air conditioning apparatus that prevents window fogging due to re-evaporation of condensation water.
BACKGROUND OF THE INVENTION
A hot-water heating apparatus has been used to heat air with a heater core using hot-water as a heat source by circulating the hot-water (engine coolant) through the heater core during vehicle compartment heating during winter. In this case, when the hot-water temperature is low, the air outlet temperature is also low and thereby not attaining sufficient heating.
Therefore, JP-B2-5-39807 discloses a heating circuit further combined with a hot-water heating apparatus to operate a heating circuit when the air outlet temperature of the hot water heater core or hot-water temperature is lower than a predetermined temperature and to improve heating capability by heating air passing through the hot water heater core with an indoor heat exchanger and heating circuit.
In some cases, an air-conditioning mode is set to filter external air during heating in winter. In this case, the air must be cooled and dehumidified to prevent fogging. Therefore, the indoor heat exchanger is operated as an evaporator for operating the heating circuit to cool air until the external air temperature is lowered up to about 0° C.
Therefore, in some cases, the heating circuit is operated for heating because the heating capability is reduced after the heating circuit cools to prevent fogging when the external air temperature is about 0° C. Moreover, in some cases, the heating circuit is stopped after cooling and then started again to heat.
In the above cases, since the condensed water generated during cooling remains on the surface of the indoor heat exchanger, if the heating circuit is operated to heat, the indoor heat exchanger radiates the heat as a high pressure side heat exchanger (heat radiator of coolant gas) and thereby rapidly increasing the temperature of the indoor heat exchanger. As such, the condensed water on the surface of the indoor heat exchanger is re-evaporated and is blown into the vehicle compartment, thereby causing fogging.
Moreover, the condensed water generated during cooling with the indoor heat exchanger is not easily evaporated at the lower external air temperature during winter and thereby remains for a long time. Therefore, fogging is sometimes caused when heating begins with the heating circuit even after a certain period of time has passed after switching to cooling.
SUMMARY OF THE INVENTION
The present invention provides an air-conditioning apparatus for heating a vehicle compartment with a hot-water heating apparatus using hot-water as the heat source and using a heating circuit to defog with re-evaporation of condensed water in the indoor heat exchanger during heating circuit heating.
In one aspect of the invention, an indoor heat exchanger operates as a low pressure side heat exchanger during the heating circuit cooling and as a high pressure side heat exchanger during heating circuit heating. A heater core is positioned downstream of the indoor heat exchanger to heat the air using the hot-water as the heat source, whereby the air heating capability of the indoor heat exchanger is limited so that the temperature of indoor heat exchanger becomes lower than the first predetermined temperature during heating circuit heating.
Accordingly, the temperature of the indoor heat exchanger is maintained lower than the first predetermined temperature (Te1) during the air heating operation. Therefore, re-evaporation of the condensed water on the surface of the indoor heat exchanger can be suppressed during heating. Therefore, fogging resulting from the highly humidified air is suppressed by setting the first predetermined temperature (Te1) to a low temperature such that the condensed water is not easily re-evaporated, for instance 10° C.
As a supply source of the hot-water to the heater core, a fuel battery or the like can be used in addition to the vehicle engine.
In another aspect, the present invention includes a determining means to determine whether the vehicle window glass is fogged or not to limit the air heating capability of the indoor heat exchanger when the determining means determines that the window glass is fogged.
Accordingly, when it is determined that the window glass is fogged during heating, the air heating capability of the indoor heat exchanger is limited to reduce blowing highly humidified air to suppress fogging. Moreover, when window glass is not fogged, this action is cancelled.
In another aspect, a determining means can determine whether fogging has occurred based on humidity near the windows as compared with general humidity. Here, humidity near the windows can be calculated (estimated) from the vehicle environment and operating conditions of the air-conditioning apparatus, in addition to the direct detection with a humidity sensor. For example, humidity of the indoor air near the window glass can be calculated (estimated) based on the physical amount in relation to the temperature of window glass. The physical amount in relation to the temperature of window glass can also be calculated (estimated) from the temperature of the window glass and some other physical quantity such as external air temperature, vehicle speed or the like correlated to the above physical amount.
Moreover, since the indoor air humidity correlates to the temperature near the window glass (when the temperature is higher, relative humidity is lower), air humidity can be estimated from the indoor air temperature near the window glass and this indoor air temperature near the window glass can be estimated from the outlet temperature of the air-conditioning apparatus.
As such, in another aspect, hot-water temperature is used as a physical amount in relation to the indoor air humidity near the window glass and it can be determined that the window glass is fogged when the hot-water temperature is lower than the predetermined hot-water temperature (Two). Namely, since the outlet temperature of the air-conditioning apparatus changes depending on the temperature of hot-water circulating in the heater core, it is determined whether the window glass is fogged or not based on the hot-water temperature.
In another aspect, the determination level (Two) of the hot-water temperature can be varied depending on the change of the external air temperature closely correlated with the temperature of the window glass and thereby fogging can be determined accurately by compensating the predetermined hot-water temperature (Two) to a higher temperature side through a drop of the external air temperature.
In another aspect, the determining means can determine whether the window glass is fogged based on the record of the heating circuit cooling.
In another aspect, the temperature of the indoor heat exchanger corresponding to an assured resistance pressure (P
0
) when the indoor heat exchanger operates as a low pressure side heat exchanger is set as a second predetermined temperature (Te2). Thereby, the air heating capability of the indoor heat exchanger is controlled to set the temperature of the indoor heat exchanger higher than the first predetermined temperature (Te1) but lower than the second predetermined temperature (Te2) when the determining means determines that the window glass is not fogged. As such, when the window glass is not fogged, the air heating capability of the heating circuit can be enhanced by setting the temperature of the indoor heat exchanger higher than the first predetermined temperature (Te1). Moreover, the indoor heat exchanger designed as the low pressure s
Itoh Satoshi
Izawa Satoshi
Kobayashi Ryo
Shimizu Toshitaka
Takano Yoshiaki
Ciric L V
Harness Dickey & Pierce PLC
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