Vehicle cooling system with system motor control apparatus

Refrigeration – With internal-combustion engine

Reexamination Certificate

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Details

C062S133000

Reexamination Certificate

active

06199398

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to, and claims priority from, Japanese Patent Applications Hei. 9-340311 and Hei. 10-343153, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates generally to a vehicle cooling system, and particularly to a control apparatus for controlling cooling of a vehicle radiator and air-conditioning condenser.
2. Discussion
A vehicle cooling apparatus is disclosed in Japanese Patent Application Laid-Open No. Hei. 4-365923. In this related art apparatus, an electric cooling fan for drawing cooling air through a radiator is controlled by pulse width modulation (PWM) in correspondence with the temperature of cooling water passing through the radiator.
In such an apparatus, a main battery and a sub battery are mounted in the vehicle, and the sub battery is used when the cooling water temperature reaches a predetermined high temperature. More particularly, the main battery and the sub battery are connected in series, and, when the cooling water temperature reaches the predetermined high temperature, the input power of a cooling fan electric motor is increased above the motor's rated input power (motor rated input power is defined as the input power of a motor in a control circuit in which an air conditioner start-up fan control voltage, or a fan voltage reached when refrigerant pressure exceeds a predetermined value, approximately equals a vehicle battery voltage under a vehicle standard voltage).
However, because the above apparatus requires two batteries, space required for the apparatus and overall vehicle cost are both increased. Also, because a switching circuit for the main battery/sub battery series connection is required, the number of parts and overall system complexity are increased.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a vehicle cooling apparatus which is of a simple construction, thereby enabling the size of the associated electric motor to be reduced and the need for an extra battery to be eliminated.
Accordingly, the present invention provides a controller that generates motor control signals in response to sensed system operating parameters, and a switching device that receives the motor control signals from the controller and that drives the motor in response thereto. The controller generates the motor control signals at a highest target duty ratio among target duty ratios calculated based on the sensed system operating parameters. This highest target duty ratio results in an input power provided to the motor by the switching device to be below a rated input power of the motor when the sensed system operating parameters are below a predetermined level. The highest target duty ratio remains above the rated input power only for a predetermined time period when a system operating parameter is above the predetermined level.
Thus with the present invention, while only a small electric motor is required, an input power greater than the rated input power of the electric motor can be applied via a change in the duty ratio. Consequently, an additional battery is not necessary, and the cooling apparatus structure is simplified.
Also, in the present invention, the time that the electric motor is used at or above its rated input power is kept short. Compared to a conventional system in which the electric motor is used at or above its rated input power for longer than the predetermined time, the durability of the electric motor is increased.


REFERENCES:
patent: 4425766 (1984-01-01), Claypole
patent: 4441462 (1984-04-01), Budinski
patent: 4590772 (1986-05-01), Nose et al.
patent: 5947189 (1999-09-01), Takeuchi et al.
patent: 5957663 (1999-09-01), Van Houten et al.
patent: 4-365923 (1992-12-01), None
patent: 8-260965 (1996-10-01), None

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