Electric device mounting structure

A mounting structure for an electric device of a vehicle includes a case body configured to accommodate the electric device inside the case body, at least one fixing portion provided continuously with the case body and configured to be fixed to a vehicle body of the vehicle, and at least one hollow portion disposed between the case body and the fixing portion. When a load from the vehicle body is transmitted to the fixing portion, the hollow portion is deformed and/or broken by the load so that the load can be absorbed. Thus, transmission of the load to the case body can be suppressed.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent Application No. 2016-166286 filed on Aug. 26, 2016, the entire content of which is incorporated herein by reference.

FIELD OF INVENTION

The present invention relates to a structure for mounting an electric device to a vehicle body.

RELATED ART

Recently, electric vehicles (EVs) in each of which drive wheels are driven by a drive motor, or hybrid vehicles each of which is designed to use a drive motor and an engine in combination to obtain power for driving the vehicle have been developed and put into practical use. As the hybrid vehicles, not only hybrid electric vehicles (HEVs) in each of which a power generator is driven by an engine to generate electric power to thereby charge a battery for feeding electric power to a drive motor, but also plug-in hybrid electric vehicles (PHEVs) in each of which a battery can be charged even by an external commercial power supply have been developed and put into practical use.

In such an electric vehicle, a DC-AC converter (inverter) for driving a drive motor is mounted. The inverter generally has high-voltage electric components housed inside a case made of a casting. The case of the inverter is fixed to a member through a mount material. The member is a skeleton member of a drive system room of the vehicle.

When an external impact is imposed on the vehicle due to collision etc., an impact load from the member is transmitted to the case of the inverter from a fixing portion. There is therefore a fear that the case may be damaged. In a technique according to the related art, a bendable portion is formed in a portion of the member to which the case of the inverter is fixed. When an impact load is input, the bendable portion is bent so that the inverter can be retracted not to interfere with another member. As a result, damage of the case can be avoided (see, e.g., JP 2015-189365A).

Since the bendable portion is bent to move the case and retract the inverter, the fixing portion and the case may be broken after the retraction depending on the magnitude of the impact load. Thus, there is a fear that the case may be damaged.

SUMMARY

Illustrative aspects of the present invention provide an electric device mounting structure according to which a case body can be suppressed from being damaged by a load from a vehicle body.

According to an illustrative aspect of the present invention, the structure includes a case body configured to accommodate the electric device inside the case body, at least one fixing portion provided continuously with the case body and configured to be fixed to a vehicle body of the vehicle, and at least one hollow portion disposed between the case body and the fixing portion.

DETAILED DESCRIPTION

An overall structure according to an embodiment of the present invention for mounting an electric device will be described with reference toFIGS. 1 and 2.FIG. 1is a front perspective view of a power unit room (an engine room) to illustrate a state in which a case body accommodating an inverter inside is supported by the electric device mounting structure according to the embodiment of the present invention, andFIG. 2is an exploded perspective view in which the case body is detached.

As shown inFIGS. 1 and 2, upper frames2are connected to left and right front pillars1respectively. The upper frames2extend to the front of a vehicle body. The upper frames2paired with each other are disposed on opposite sides in a vehicle width direction. The front pillars1are coupled to each other by a cowl top panel3. A dash panel4is disposed below the cowl top panel3. Thus, the power unit room R is separated from a vehicle cabin.

A power unit6of a drive motor, an engine etc. is mounted in the power unit room R. In addition, a DC-AC converter (inverter)11, as an electric device for driving the drive motor, is mounted in a state in which it is accommodated inside a case body12. The case body12is fixed to one of the upper frames2serving as a vehicle body side.

That is, a front attachment bracket14is fixed to a vehicle front side of the upper frame2. At least one fixing portion15is provided at one or a plurality of places of the case body12. In the Example, fixing portions15having bolt holes are provided at two places on the vehicle front side of the case body12. The fixing portions15are formed integrally with the case body12through a fixing bracket16. The vehicle front side of the case body12is fixed to the front attachment bracket14through the fixing portions15.

In addition, a rear attachment bracket17is fixed to a vehicle rear side of the upper frame2. The vehicle rear side of the case body12is fixed to the rear attachment bracket17through not-known metal fittings. Thus, the inverter11accommodated inside the case body12is fixed to the vehicle body side (upper frame2).

A hollow portion is disposed in the fixing bracket16between the case body12and the fixing portions15. When a load from the vehicle body (load from the front) is transmitted to the fixing portions15of the fixing bracket16, the hollow portion (fragile portion) disposed thus is deformed and/or broken to absorb the load. Thus, transmission of the load to the case body12can be suppressed to the minimum.

The structure for mounting an electric device (the inverter11in the present example) will be described in more detail with reference toFIGS. 3 to 5.FIG. 3is a bottom view of the case body.FIG. 4is a bottom perspective view of the case body12illustrating the fixing portions15.FIG. 5is a sectional view of taken along the line V-V inFIG. 3including a section of one of the fixing portions15.

As shown inFIGS. 3 to 5, the fixing bracket16between the case body12and the fixing portions15is configured to connect the fixing portions15at the two places continuously. At least one hollow portion21is disposed on a back side of the fixing bracket16. In the Example, the fixing portions15at the two places are connected to each other through the fixing bracket16having a series of hollow portions21.

In the present example, a curved wall portion22bulging toward the case body12is formed on a case body12side of each of the fixing portions15. The hollow portions21are also disposed between the case body12and the curved wall portions22. When a plurality of ribs23each extending in a front/rear direction of the vehicle are disposed in the vehicle width direction, the hollow portions21of the present example are provided at a plurality of places in the width direction of the fixing bracket16. That is, the hollow portions21are disposed three-dimensionally.

As shown inFIG. 5, a thickness h of a vehicle front side wall25for forming the hollow portions21is formed to be thinner than a thickness H of a wall26on the case body12side. Therefore, when a load acts rearward from the front of the vehicle, a portion of the vehicle front side wall25(e.g., an upper end of the wall25) is deformed and/or broken earlier than the wall26on the case body12side. Accordingly, deformation and/or breakage of the case body12can be suppressed.

The ribs23are disposed between the case body12and the fixing portions15so that at least one hollow portion21can be provided. Accordingly, deformation and/or breakage caused by the load can be allowed while rigidity for supporting the case body12inside which the inverter11is accommodated is ensured.

In the example described above, the case body12is made by, for example, aluminum casting. The case body12is cast and manufactured integrally with the fixing portions15(bolt insertion holes) and the hollow portions21. In addition to the inverter11for driving the drive motor, a DC-DC converter, a charging device, a battery pack etc. can be applied as the electric device accommodated inside the case body12.

A behavior of the mounting structure for the inverter11will be described primarily with reference toFIGS. 6 and 7(partially with reference toFIG. 3).

FIG. 6is an external view of the mounting structure when a load is input from the front.FIG. 7is a sectional view of the mounting structure when the load is input from the front.

As shown inFIGS. 6 and 7, when the load P from the front of the vehicle body is transmitted to the fixing portions15of the fixing bracket16in the mounting structure for the inverter11having the aforementioned configuration, the hollow portions21(fragile portions) are deformed and/or broken by the load so that the load can be absorbed. Thus, transmission of the load from the vehicle body to the case body12can be suppressed to the minimum. Therefore, damage of the case body12caused the load from the vehicle body can be suppressed.

In addition, the plurality of (two in the present example) fixing portions15are connected to one another through the series of the hollow portions21. Accordingly, when a load P is input to one of the fixing portions15, the load P can be absorbed by the series of the hollow portions21as a whole (stress in reaction to the load P can be dispersed). As a result, transmission of the load from the vehicle body can be suppressed regardless of the input place of the load P.

In addition, the curved wall portions22are formed on the case body12sides of the fixing portions15. Accordingly, the hollow portions21are provided three-dimensionally so that the hollow portions21can absorb the load P in multiple directions (radially) in dispersed manner. As a result, transmission of the load P from the vehicle body side can be suppressed regardless of the input direction of the load P. In other words, loads P from different directions can be absorbed and transmission of any load P from any direction can be suppressed.

In the mounting structure for the inverter11described above, when the load P is input from the front of the vehicle, the hollow portions21(fragile portions) can be deformed and/or broken to absorb the load P. Accordingly, the case body12moves relative to the fixing portions15(movement of an absolute position of the case body12is suppressed to the minimum) so that damage of the case body12can be avoided.

The fixing bracket16may include a flat wall portion24as shown inFIG. 3, and may further include an upper wall27between the front wall25and the rear wall26, and a lower wall28as shown inFIG. 5.