Engine cooling apparatus

#The present invention relates to an engine cooling apparatus, which cools down an engine by circulating a coolant, and more particularly to an engine cooling apparatus, which controls the flow rate of the coolant that passes through a radiator provided in a coolant circulation passage of the engine.

#As a conventional cooling apparatus provided in an engine, the most popular type has been one, which uniformly adjusts a coolant to a temperature of approximately 80° by a thermostat irrespective of an operation state of the engine. In order to achieve reduction in friction of the engine, improvement in fuel consumption or knocking performance and others, however, it is confirmed that changing a degree of cooling in accordance with an operation state of the engine (load condition, rotational speed or the like) is effective. Therefore, there have been proposed several cooling apparatuses designed to control a degree of cooling in accordance with an operation state of the engine.

#As this type of cooling apparatus, for example, there is an engine cooling apparatus disclosed in Japanese Laid-Open Patent Publication No. 5-179948. This engine cooling apparatus is configured for the purpose of adjusting a temperature of a coolant that circulates in the engine in accordance with the load condition of the engine. That is, this apparatus is designed to set a target temperature of the coolant based on the load condition of the engine and controls a flow rate of the coolant that passes through a radiator in such a manner that a temperature of the coolant that flows on an outlet side of a water jacket reaches this target temperature. More specifically, a temperature difference between an actual coolant temperature detected by a coolant temperature sensor and the target temperature is obtained. Further, an amount of duty change is obtained from this temperature difference by making reference to map data, and a temperature of the coolant that flows on the outlet side of the water jacket is adjusted to the target temperature by controlling a flow regulating valve, which adjusts a flow rate of the coolant passing through the radiator, based on the amount of duty change.

#The invention, together with objectives and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

#FIG. 1 is a schematic block diagram of an engine cooling apparatus according to a first embodiment of the present invention;

#FIG. 2 is a cross-sectional view showing a flow regulating valve of FIG. 1;

#A first embodiment, which embodies an engine cooling apparatus according to the present invention, will now be described in detail hereinafter with reference to the accompanying drawings.

#FIG. 1 shows a schematic structure of an engine cooling apparatus according to this embodiment. An engine 1 mounted in a vehicle includes a cylinder block 2 and an engine head 3. This cooling apparatus cools down the engine 1 by circulating a coolant, and a coolant passage 4 including a water jacket is provided to the cylinder block 2 and the engine head 3.

#An outlet 4a and an inlet 4b of the coolant passage 4 are connected by a main piping 5, and the coolant passage 4 and the main piping 5 constitute a coolant circulation passage according to the present invention. There are provided a first coolant temperature sensor 31, a radiator 7, a second coolant temperature sensor 32, a flow regulating valve 8 and a water pump (W/P) 9 in this order in the middle of the main piping 5 from the outlet 4a toward the inlet 4b.