Ventilation – Vehicle – Condensation preventer
Patent
1995-09-25
1997-04-29
Joyce, Harold
Ventilation
Vehicle
Condensation preventer
62182, B60S 154
Patent
active
056243103
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention is related to air conditioning systems for vehicles and in particular, but not exclusively, for motor cars which have an air heated window, particularly a windscreen.
BACKGROUND
Most vehicles are now equipped with air conditioning and heating systems for maintaining the air within the vehicle passenger compartment at a set desired temperature value.
The air conditioning system supplies an air flow of controllable temperature to the passenger compartment. There are two types of air conditioning systems: a) an Automatic Climate Control (ACC) in which the temperature in the passenger compartment is monitored by a temperature sensor and the system is operated to maintain the passenger compartment at a desired temperature, and b) Automatic Temperature Control (ATC) in which the temperature of the air leaving the air distribution system is regulated to a desired temperature.
A problem that can occur with the air conditioning systems which have a heat exchange system including an evaporator, is that when the vehicle is left dormant after use, and then re-used after a short time period of idleness, usually in the order of one minute to 12 hours, then when the air conditioning system is reactivated large quantities of moisture laden air may be blown onto the windscreen if the system is set to windscreen demise or defrost. If the ambient air temperature is within the range 0-22 degrees C then the moisture in the air coming from the heating, ventilation and air conditioning unit (HVAC-unit) may condense on the glass areas inside the car reducing the sight of the driver.
This effect is caused by the evaporator having become chilled during previous use of the air conditioning system and therefore having a considerable amount of water condensed on the evaporator surface. During a vehicle stand still, or deactivation of the air conditioning system, the evaporator warms up above the ambient air temperature and the large quantities of water on the surfaces saturates the warmer air around the evaporator. If the air conditioning system blower is started in this condition the moisture laden air is carried away from the evaporator and if the system is set to windscreen defrost/defog position, or if air leaks to defrost/defog air ducts, then the moisture laden air is deposited on the glass areas.
SUMMARY OF THE INVENTION
The present invention seeks to prevent the depositing of large amount of condensate on the inside of the glass areas when first activating an air conditioning system after the vehicle has been dormant for a short period of time.
According to the invention there is provided an air conditioning system for a vehicle having a compartment with at least one window which is heatable by an air flow of controlled temperature, the air conditioning system including a distribution system which directs air flow to the window, a heat exchange system which includes an evaporator, a fan or blower for forcing air over the evaporator and a control means connected to the fan, characterised in that the control means includes a means for deactivating the fan for a predetermined time limit after activation of the air conditioning system.
The fan or blower has to be deactivated until the evaporator (or cooling device) has reached the optimum low temperature, which means between 5-20 seconds after activating the air conditioning compressor (in a reversed Carnot-cycle) and normally about 10 seconds.
Preferably the system further includes an external temperature sensor and is characterised in that the deactivating means is activated by the control means in response to signals from the external temperature sensor.
Conveniently the system further includes a solar sensor for sensing the intensity of the suns rays and which is connected to the control means, characterised in that the deactivation means is operably controlled by the control means in response to signals from the solar sensor.
Also according to the invention there is provided a method of controlling the air condition sys
REFERENCES:
patent: 2492970 (1950-01-01), Curry
patent: 4860552 (1989-08-01), Beckey
patent: 5167365 (1992-12-01), Mitoshi et al.
patent: 5301515 (1994-04-01), Iritani et al.
Andersson Thomas
Fredriksson Bernt
Joyce Harold
Saab Automobile Aktiebolag
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