Cooling device of an engine

Details Cooling device of an engine Cooling device of an engine

1999-04-23

2001-03-13

Kwon, John (Department: 3747)

Internal-combustion engines

Cooling

With liquid coolant circulating means

C123S041470

Reexamination Certificate

active

06199518

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a cooling device of an engine which cools the engine by circulating a cooling liquid.
DESCRIPTION OF THE PRIOR ART
A conventional cooling device of this kind includes a liquid pump which is driven by a rotational force of a crank shaft and which circulates the cooling liquid in a cooling liquid circuit of an engine in order to cool the engine. In this conventional cooling device, the liquid pump is always driven by the rotational force of the crank shaft during engine operation and it is impossible to adjust the flow rate of the cooling liquid discharged by the liquid pump. Therefore, the flow rate or flowing amount of the cooling liquid discharged by the liquid pump becomes larger than the flow rate required for cooling the engine under certain circumstances and the consumption of fuel increases due to the greater load on the engine.
A cooling device which overcomes these drawbacks is disclosed in Japanese patent application laid-open publication No. 62(1987)-210287. This cooling device includes a liquid pump which is driven by the rotational force through an electromagnetic clutch in order to circulate the cooling liquid in the cooling liquid circuit of the engine. In this cooling device, the transmission of the rotational force from the crank shaft to the liquid pump is controlled by the electromagnetic clutch and the liquid pump is efficiently driven by the rotational force of the crank shaft. On the other hand, a driving device for driving a auxiliary apparatus of the engine such as a distributor is disclosed in Japanese utility model application laid-open publication No. 2(1990)-135616. In this driving device, the auxiliary apparatus is driven by the rotation of a cam shaft. If this driving device is used as a driving device for driving a liquid pump for circulating the cooling liquid, the flow rate of the cooling liquid discharged by the liquid pump is prevented from becoming greater than the flow rate required for cooling the engine.
In the cooling device disclosed in the former publication, however, the electromagnetic clutch is disposed so as to be coaxial with a shaft of the liquid pump and to surround the liquid pump, and the size of the liquid pump is increased in the axial and radial directions. As a result, the cooling device is restricted by the space required for installing on the engine. Further, in the device disclosed in the latter publication, since the rotation of the crank shaft is transmitted to the cam shaft while being reduced and the rotational speed of the cam shaft becomes half that of the crank shaft, the flow rate of the cooling liquid required for cooling the engine is not ensured and cooling performance deteriorates.
Recently, a cooling device which includes a liquid pump and an electric motor which drives the liquid pump was suggested and is disclosed in Japanese Patent application laid-open publication No. 5(1993)-231149. The liquid pump is driven by the electric motor in response to the temperature of the cooling liquid. In this cooling device, it is able to more efficiently drive the liquid pump in response to the running condition of the engine. However, since a suitable cooling effect for the engine is obtained only by the liquid pump driven by the electric motor, scaling up of the electric motor is required and therefore the consumption of the electric power out of the system in order to drive the electric motor increases.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide an improved cooling device of an engine which overcomes the above drawbacks.
In order to achieve this objective, there is provided a cooling device of an engine which includes a first liquid pump driven by decelerated rotation of an engine for circulating the cooling liquid in the engine and a second liquid pump driven by electricity for circulating the cooling liquid in the engine as a supplement.


REFERENCES:
patent: 4759316 (1988-07-01), Itakura
patent: 5095855 (1992-03-01), Fukuda et al.
patent: 5979394 (1999-11-01), Schmidt
patent: 2 160 588 (1985-12-01), None
patent: 62-210287 (1987-09-01), None
patent: 2-135616 (1990-11-01), None
patent: 5-231149 (1993-09-01), None
patent: 9-88585 (1997-03-01), None
patent: 89-04419 (1989-03-01), None

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