Cooling system for electric vehicle and cooling method for electrical component

A cooling system for an electric vehicle is provided, wherein an exhaust air duct extending into a box is disposed in an air outlet of the box disposed in a lower portion of the vehicle interior; an air discharge port of the fan case coupled to the air outlet portion of the cooling duct faces an air inlet of the exhaust air duct with a predetermined gap therebetween in a direction of air flow; and when the air discharge port of the fan case is projected on a plane including the air inlet of the exhaust air duct, the air discharge port of the fan case is opened inside the air inlet of the exhaust air duct and a predetermined gap is formed in a transverse direction to the air flow between the air discharge port of the fan case and the air inlet of the exhaust air duct.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent Application No. 2011-096956, filed Apr. 25, 2011, which is incorporated herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a cooling system for an electric vehicle, and more particularly relates to a cooling system for an electric vehicle with improved cooling performance for an air-cooled electrical component mounted on the electric vehicle and a cooling method for the electrical component.

2. Description of Related Art

An electrical component such as a high-voltage battery, a charger, and a DC/DC converter is mounted on an electric vehicle such as a hybrid vehicle and a plug-in hybrid vehicle. These electrical components generate heat during operation and hence need to be cooled by a cooling system.

A conventional cooling system for an electric vehicle cools an electrical component in such a manner that the electrical component having a heat dissipating fin is disposed inside a box having an air inlet and an air outlet located in substantially the same position; a cooling duct covering the heat dissipating fin of the electrical component is attached thereto to form a substantially U-shaped air passage; and air is circulated through the air passage by an air blowing fan connected to the air inlet (see JP 2000-40535 A).

As disclosed in JP 2000-40535 A, the cooling system for an electric vehicle forcibly circulates air through and over the heat dissipating fins contacting a heat generating portion of the electrical component by the fan for cooling.

The cooling system for electrical components can cool the portions subjected to high temperature simply by circulating air through the heat dissipating fins. However, in a case in which the electrical component is disposed inside the box, the air inside the box is heated to high temperature by heat dissipation from a portion other than the heat dissipating fins of the electrical component. Then, when the electrical component is exposed to high temperature air, the thermal burden imposed on the electrical component increases.

In order to prevent a rise in air temperature around the electrical component, it can be considered to add not only a fan for cooling the electrical component but also a ventilation fan to ventilate the inside of the box. Unfortunately, addition of another ventilation fan is disadvantageous in that the mounting space and costs are increased.

SUMMARY OF THE INVENTION

The present invention provides a cooling system for an electric vehicle and a cooling method for an electrical component for the purpose of improving a cooling performance for the electrical component disposed inside a box without adding a dedicated ventilation fan.

The present invention provides a cooling system for an electric vehicle in which a box including an air inlet and an air outlet is disposed in a lower portion of a vehicle; an electrical component having a heat dissipating fin is disposed in the box; a cooling duct is attached to the electrical component for covering the heat dissipating fin; and a fan case having therein a fan for drawing air is coupled to an air outlet portion of the cooling duct, wherein an exhaust air duct extending into the box is disposed in the air outlet of the box; an air discharge port of the fan case faces an air inlet of the exhaust air duct with a predetermined gap therebetween in a direction of air flow; and when the air discharge port of the fan case is projected on a plane including the air inlet of the exhaust air duct, the air discharge port of the fan case is opened inside the air inlet of the exhaust air duct and a predetermined gap is formed in a transverse direction to the air flow between the air discharge port of the fan case and the air inlet of the exhaust air duct.

Furthermore, the present invention also provides a cooling method for an electrical component in an electric vehicle including a box disposed in a lower portion of a vehicle interior and including an air inlet and an air outlet; an electrical component disposed in the box and having a heat dissipating fin; a cooling duct attached to the electrical component and covering the heat dissipating fin; and a fan case coupled to an air outlet portion of the cooling duct and having therein a fan for drawing air, wherein an exhaust air duct extending into the box is disposed in the air outlet of the box; an air discharge port of the fan case faces an air inlet of the exhaust air duct with a predetermined gap therebetween in a direction of air flow; and a predetermined space formed between the air discharge port of the fan case and the air inlet of the exhaust air duct is set such that the relationship P1>P2>P3 is satisfied when the air drawn by the fan flows from the air discharge port of the fan case to the air inlet of the exhaust air duct, where P1 represents a pressure inside the fan case, P2 represents a pressure around the fan case, and P3 represents a pressure inside the exhaust air duct.

The cooling system for an electric vehicle according to the present invention can efficiently cool the heat dissipating fins of the electrical component by using a fan to draw air inside the cooling duct covering the heat dissipating fins.

Furthermore, when the air drawn by the fan flows from the air discharge port of the fan case to the air inlet of the exhaust air duct, portions other than the heat dissipating fins of the electrical component can be efficiently cooled by a negative pressure generated by the gaps formed therebetween to discharge hot air remaining inside the box containing the electrical component outside the vehicle.

Thus, the cooling system for an electric vehicle according to the present invention can improve the cooling performance for the electrical component installed in the box without adding a new dedicated ventilation fan for ventilating the inside of the box.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Now, with reference to the accompanying drawings, an embodiment of the present invention will be described.

Embodiment

FIGS. 1 to 10illustrate an embodiment of the present invention.FIG. 10illustrates an electric vehicle1, a vehicle interior2, a front wheel3, and a rear wheel4. As illustrated inFIGS. 8 and 9, the electric vehicle1includes a vertical wall6extending upward at a rear end of a front floor5; and a rear floor7extending backward at an upper end of the vertical wall6. Furthermore, the electric vehicle1includes a seat support portion8having an inverted U-shaped cross-section and extending in a vehicle width direction at a front portion of the front floor5; and a front seat9mounted thereon.

Furthermore, the electric vehicle1includes an upper floor10extending frontward parallel to the front floor5from an upper end of the vertical wall6; and a front wall11extending downward from a front end of the upper floor10and connecting to the front floor5. Furthermore, the electric vehicle1includes a rear portion12of the front floor5located between the vertical wall6and the front wall11; a right side wall13and a left side wall14disposed on respective opposite sides of the rear portion12in the vehicle width direction and extending up to the upper floor10; a right side partition wall15and a left side partition wall16disposed in between the right side wall13and the left side wall14; and a rear seat17disposed on the upper floor10.

The electric vehicle1includes a box19that is defined by the right side wall13, the right side partition wall15, and the vertical wall6, the upper floor10, the front wall11and the rear portion12located between the right side wall13and the right side partition wall15, and forms a part of a cooling system18. The box19is disposed on a right side of a lower portion of the vehicle interior2in the vehicle width direction. The box19includes an air inlet20located in substantially the center of the front wall11and facing inside the vehicle interior2; and an air outlet21located on a rear side of the right side wall13and facing outside the vehicle. The box19includes thereinside an electrical component22such as a high-voltage battery, a charger, and a DC/DC converter.

As illustrated inFIGS. 3A and 3B, the electrical component22has heat dissipating fins23on the underside thereof. The electrical component22has a cooling duct24covering the heat dissipating fins (heat radiating fins)23. As illustrated inFIGS. 1 and 2, in the cooling duct24, an air inlet portion25is disposed facing the air inlet20of the front wall11and a suction side of a fan case27is coupled to an air outlet portion26. The fan case27includes an air discharge port28facing an air outlet21of the box19; and a fan29for drawing air inside. The air outlet21of the box19has an exhaust air duct30extending toward the fan case27disposed in the box19. The exhaust air duct30has an air inlet31facing the air discharge port28of the fan case27.

In the cooling system18, as illustrated inFIG. 4, the air discharge port28of the fan case27faces the air inlet31of the exhaust air duct30with a predetermined gap S1therebetween in a direction of the air flow. Furthermore, in the cooling system18, as illustrated inFIGS. 5 and 6, when the air discharge port28of the fan case27is projected on a plane including the air inlet31of the exhaust air duct30, the air discharge port28of the fan case27is opened to inside the air inlet31of the exhaust air duct30, and a predetermined gap S2is formed in a transverse direction to the air flow between the air discharge port28of the fan case27and the air inlet31of the exhaust air duct30. Thus, the cooling system18forms a predetermined space32including the gaps S1and S2between the air discharge port28of the fan case27and the air inlet31of the exhaust air duct30.

The cooling system18can efficiently cool the heat dissipating fins23of the electrical component22by using a fan29disposed in the fan case27coupled to the cooling duct24to draw air inside the cooling duct24covering the heat dissipating fins23and discharge the air through the exhaust air duct30to outside the vehicle.

Furthermore, thanks to the predetermined space32formed between the air discharge port28of the fan case27and the air inlet31of the exhaust air duct30as illustrated inFIG. 7, the relationship P1>P2>P3 is satisfied in the cooling system18when the air drawn by the fan29flows from the air discharge port28of the fan case27to the air inlet31of the exhaust air duct30, where P1 represents a pressure inside the fan case27, P2 represents a pressure around the fan case27, and P3 represents a pressure inside the exhaust air duct30.

Thus, the cooling system18uses a negative pressure (differential pressure) generated by the gaps S1and S2formed between the fan case27and the exhaust air duct30to discharge hot air remaining inside the box19containing the electrical component22to outside the vehicle interior2. Accordingly, the cooling system18can cool portions other than the heat dissipating fins23of the electrical component22by taking in the air inside the vehicle interior2through the air inlet20into the box19.

Thus, the cooling system18can improve the cooling performance for the electrical component22installed in the box19without adding a new dedicated ventilation fan for ventilating the inside of the box19.

Furthermore, the conventional cooling system has a problem in that when a fan case27is directly bonded to an exhaust air duct30, the bonded portion between the fan case and the exhaust air duct needs to have a structure for preventing backlash and air leaks, thus complicating the bonding structure. In contrast to this, the cooling system18has gaps S1and S2formed between the air discharge port28of the fan case27and the air inlet31of the exhaust air duct30, which can simplify the structure of the bonded portion between the fan case27and the exhaust air duct30, leading to an improvement in manufacturability and a reduction in costs, which is advantageous in terms of assembly.

Furthermore, the cooling system18is structured such that the cooling air generated by the fan29is discharged outside the vehicle interior2, thereby to guide the air inside the vehicle interior2into the box19and then to discharge it outside the vehicle interior2. Thus, the inside of the vehicle interior2can be ventilated during charging of a battery mounted on the electric vehicle1. Particularly in summer, the temperature inside the vehicle interior2rises during charging of the electric vehicle1if the windows are closed, but the cooling system18can alleviate the temperature rise. Thus, the cooling system18can improve the ventilation performance inside the vehicle interior.

The cooling system for an electric vehicle according to the present invention can improve the cooling performance for an electrical component installed in the box and can be applied to cool a heat generating device installed in the box of not only an electric vehicle but also a vehicle mounting an internal combustion engine.