JP6981228B2 - Power control unit mounting structure - Google Patents

Description

The present invention relates to a mounting structure of a power control unit for driving a traveling motor in a front compartment.

Patent Document 1 discloses a mounting structure of the power control unit in the front compartment. In the technique disclosed in Patent Document 1, the front and rear of the power control unit are supported by a front bracket and a rear bracket, and the power control unit is fixed with a gap above the housing accommodating the motor. The reason why the front bracket and the rear bracket secure a gap between the power control unit and the housing is to suppress the vibration of the motor transmitted to the power control unit through the housing. In the following, for convenience of explanation, the front bracket and the rear bracket may be simply referred to as "bracket" when they are referred to without distinction. When referring to both the front bracket and the rear bracket, it may be referred to as "both brackets".

A power cable that transmits power of several tens of kilowatts or more is connected to the power control unit. In the mounting structure of Patent Document 1, the rear bracket includes a base fixed to the housing and a support portion extending from the base to support the power control unit. The base is provided with an arch for passing the power cable to and from the housing in the front-rear direction of the vehicle. Further, a surrender portion is provided in the support portion above the base portion. When a vehicle collides, the power control unit supported with a gap between it and the housing may be loaded from the front and retracted. When a load exceeding a predetermined value is applied to the rear bracket, the yielding portion yields first and the supporting portion bends backward. Since the support part bends above the arch part, the cable passing under the arch part is not caught in the deformation of the rear bracket.

FIG. 9 shows the rear bracket 140 disclosed in Patent Document 1. FIG. 9 shows the rear portion of the power control unit 20 and the rear bracket 140 as viewed from diagonally rearward. The power control unit 20 is supported by a rear bracket 140 and a front bracket (not shown) with a gap between the upper surface 30a of the housing 30. The connector 23 of the power cable 24 is connected to the rear surface 20c of the power control unit 20. In FIG. 9, the power cable 24 and the connector 23 are drawn by virtual lines. The rear bracket 140 includes a base 143 fixed to the housing 30 and a support 141 extending from the front end of the base 143 to the power control unit 20. The base portion 143 is provided with an arch portion 144 through which the power cable 24 passes in the front-rear direction of the vehicle between the base portion 143 and the housing 30. Further, ribs 145 are provided at both ends of the support portion 141, and through holes 146 are provided substantially in the center of the ribs 145 in the vertical direction. The through hole 146 corresponds to the yield portion described above. At the time of a collision, when the power control unit 20 receives a load from the front, the support portion 141 bends at the portion of the through hole 146 whose strength (rigidity) is low, and the impact of the collision is mitigated.

Japanese Unexamined Patent Publication No. 2017-024466

The technique disclosed herein relates to an improvement in the rear bracket in the mounting structure of Patent Document 1 in terms of weight reduction, ease of manufacture, and the like.

This specification discloses a mounting structure of a power control unit for driving a traveling motor in the front compartment. The power control unit is supported by a front bracket and a rear bracket at the front and rear thereof, and is fixed with a gap above the housing for accommodating the motor. The rear bracket comprises a base that is secured to the housing and a support that extends from the front end of the base to the power control unit. The base is provided with an arch for passing cables to and from the housing in the front-rear direction of the vehicle. The rear end of the arch portion in the vehicle front-rear direction is located in front of the vehicle from the fastening point where the base is fastened to the housing.

As shown in FIG. 9, in the conventional rear bracket 140, the arch portion 144 extends from the front end to the rear end of the base portion 143. In other words, the arch portion 144 extends to the rear of the bolt 54 (fastening portion) fixing the base portion 143 to the housing 30. Since the arch portion 144 has an effect of increasing the strength near the boundary between the base portion 143 and the support portion 141, the long arch portion 144 significantly increases the strength near the boundary between the base portion 143 and the support portion 141. In the conventional rear bracket 140, in the case of a collision, the support portion 141 does not break near the boundary between the support portion 141 and the base portion 143, and the support portion 141 breaks at the portion of the through hole 146 (yield portion) provided in the support portion 141. It bends and relaxes the collision load applied to the power control unit 20 from the front. The arch portion 144 extends to the rear end of the base and protects the power cable 24 passing under it. On the other hand, in the mounting structure disclosed in the present specification, the length of the arch portion in the front-rear direction is shortened, and the rigidity near the boundary between the base portion and the support portion of the rear bracket is reduced. That is, in the rear bracket 140 of Patent Document 1, the yielding portion (through hole 146) is arranged above the arch portion 144, whereas in the rear bracket disclosed in the present specification, the vicinity of the boundary between the base portion and the supporting portion is located. Corresponds to the surrender part. Since the arch part is shortened, it leads to weight reduction. Further, since it is not necessary to provide the through hole 146, the manufacturing process can be simplified. Further, since the rigidity of the rear bracket is lowered, the sharing ratio of the rear bracket can be lowered in the sharing ratio of the impact load by both brackets.

Details and further improvements to the techniques disclosed herein will be described in the "Modes for Carrying Out the Invention" section below.

It is a perspective view which shows an example of the component layout in a front compartment. It is a side view of a housing and a PCU (power control unit). It is a perspective view of a rear bracket. It is the figure which looked at the rear bracket and PCU diagonally from the rear. It is an enlarged side view near the rear bracket. It is an enlarged side view near the deformed rear bracket. It is an enlarged side view near the rear bracket (conventional example). It is an enlarged side view near the deformed rear bracket (conventional example). It is the figure which looked at the conventional rear bracket and PCU diagonally from the rear.

The mounting structure 2 of the embodiment will be described with reference to the drawings. The mounting structure 2 of the embodiment is applied to a hybrid vehicle 100 including both a traveling motor 3 and an engine 98. The hybrid vehicle 100 has an engine 98, a motor 3, and a power control unit 20 for driving the motor 3 mounted in the front compartment 90 of the vehicle. In the front compartment 90, the power control unit 20 is fixed onto the housing 30. The housing 30 houses the motor 3, the power distribution mechanism 6, and the differential gear 4. In the following, for the sake of simplicity, the "power control unit 20" is abbreviated as "PCU 20". PCU is an abbreviation for Power Control Unit.

FIG. 1 shows the arrangement of the device group in the front compartment 90. In the front compartment 90, various devices such as a battery 95 are arranged in addition to the device group in which the engine 98, the PCU 20, and the housing 30 are mounted, but the description thereof will be omitted. It should be noted that in FIG. 1, the housing 30, the engine 98, and the like are schematically drawn. In the coordinate system in the figure, the F axis indicates the front of the vehicle, the V axis indicates the upper side of the vehicle, and the H axis indicates the vehicle width direction (left side of the vehicle). The meanings of the symbols in the coordinate system are the same in the following figures. Further, in the following, expressions such as "front", "rear", "front", and "rear" are used for the parts mounted on the front compartment 90, and "front" in these expressions is the front side of the vehicle. Means, "rear" means the rear side of the vehicle.

As described above, the housing 30 houses the power distribution mechanism 6 and the differential gear 4 in addition to the motor 3. The power distribution mechanism 6 is a gear set that combines / distributes the output torque of the engine 98 and the output torque of the motor 3. The power distribution mechanism 6 divides the output torque of the engine 98 and transmits it to the differential gear 4 and the motor 3 depending on the situation. Since the differential gear 4 is built in, the housing 30 is, in other words, the case of the motor and the transaxle. The housing 30 is made of, for example, die-cast or machined from aluminum.

The engine 98 and the housing 30 are connected so as to be adjacent to each other in the vehicle width direction. The engine 98 and the housing 30 are suspended by side members 96 that ensure the structural strength of the vehicle. In FIG. 1, only one side member 96 is drawn, but in FIG. 1, another side member extends to the lower left of the engine 98. The engine 98 and the housing 30 are suspended between the two side members.

The PCU 20 is a device that drives the motor 3. More specifically, the PCU 20 boosts the power of a high-voltage battery (not shown), converts it into alternating current, and supplies it to the motor 3. The PCU 20 may also convert the AC power generated by the motor 3 into DC power and further step down the voltage. The stepped down power charges the high voltage battery.

As will be described in detail later, in the mounting structure 2 of the embodiment, the PCU 20 is supported with a gap between it and the upper surface of the housing 30. The front side of the PCU 20 is supported by the front bracket 10, and the rear side of the PCU 20 is supported by the rear bracket 40. The relationship between the housing 30 and the PCU 20 will be described in detail with reference to FIG. 1 and FIG. FIG. 2 is a side view of the PCU 20 and the housing 30. The "side surface" is a view when viewed from the vehicle width direction (H-axis direction in the figure).

The PCU 20 and the housing 30 are electrically connected by six power cables 21. The power cable 21 is a wire harness for transmitting electric power from the PCU 20 to the motor 3. Although the description is omitted, two three-phase AC motors are housed in the housing 30, and the six power cables 21 transmit two sets of three-phase AC. Reference numeral 31 indicates a power cable terminal provided on the upper surface 30a of the housing 30. Although two motors are housed in the housing 30, the description will be continued below focusing on one of the motors (motor 3).

As described above, the housing 30 houses the motor 3, the power distribution mechanism 6, and the differential gear 4. Inside the housing 30, the output shaft 3a of the motor 3, the spindle 6a of the power distribution mechanism 6, and the spindle 4a of the differential gear 4 are arranged in parallel. These three shafts extend in the vehicle width direction. As shown in FIG. 2, the three axes are arranged so as to form a triangle when viewed from the vehicle width direction. Due to the above arrangement of the three shafts, the upper surface 30a of the housing 30 is inclined forward and downward. Therefore, the PCU 20 supported above the upper surface 30a is also arranged so as to be inclined forward.

The PCU 20 is supported above the housing 30 by the front bracket 10 and the rear bracket 40. The front bracket 10 supports the front surface 20a of the PCU 20, and the rear bracket 40 supports the rear surface 20c of the PCU 20. A gap SP is secured between the lower surface 20b of the PCU 20 and the upper surface 30a of the housing 30. This gap SP is secured by the front bracket 10 and the rear bracket 40.

The front bracket 10 includes a base 13 fixed to the housing 30 and a support 11 extending from the rear end of the base 13 to the PCU 20. As described above, the rear end of the base 13 of the front bracket 10 means the rear end of the base 13 fixed on the housing 30 on the vehicle rear side.

The base portion 13 of the front bracket 10 is fixed to the upper surface 30a of the housing 30 by bolts 52, and the upper portion of the support portion 11 is connected to the front surface 20a of the PCU 20 by bolts 51. A vibration-proof bush 12 is sandwiched between the upper portion of the support portion 11 and the PCU 20. As shown in FIG. 1, the front bracket 10 is fixed to the housing 30 by three bolts arranged in the vehicle width direction and connected to the PCU 20 by two other bolts arranged in the vehicle width direction. The front bracket 10 is made by pressing a metal plate (steel plate).

The rear bracket 40 includes a base 43 fixed to the housing 30 and a support 41 extending from the front end of the base 43 to the PCU 20. The front end of the base 43 means the vehicle front end of the base 43 fixed on the housing 30.

The arrow W in FIG. 2 schematically shows the collision load that the PCU 20 receives when the hybrid vehicle 100 collides forward (or diagonally forward). When the PCU 20 receives a large impact load W from the front, both the support portion 11 of the front bracket 10 and the support portion 41 of the rear bracket 40 bend backward. The rigidity of the front bracket 10 and the rear bracket 40 is suppressed to a size that allows the front bracket 10 and the rear bracket 40 to bend when a collision load W of a predetermined size or more is applied. This is because if the rigidity of the front bracket 10 and the rear bracket 40 is too high, the damage caused by the collision load W received by the PCU 20 cannot be reduced. By deforming the front bracket 10 and the rear bracket 40, the impact received by the PCU 20 is alleviated, and the load applied to the fastening portion between the bases 13, 43 and the housing 30 is also alleviated. Further, it is desirable that the bending rigidity of the front bracket 10 and the bending rigidity of the rear bracket 40 around the axis parallel to the H axis of the coordinate system in the figure are equal to each other. This is because if the bending rigidity is different, the load sharing will be uneven between the front and rear brackets. The deformation of the rear bracket 40 due to the collision load W will be described in detail later.

The rear bracket 40 will be described in detail. A perspective view of the rear bracket 40 is shown in FIG. FIG. 4 shows a view of the PCU 20 and the rear bracket 40 as viewed diagonally from the rear. In FIG. 4, the PCU 20 is drawn with a virtual line to help understanding. In FIG. 4, a part of the housing 30 for fixing the rear bracket 40 is also drawn with a virtual line. The rear bracket 40 is formed by molding a metal plate by press working. The base 43 of the rear bracket 40 is fixed to the upper surface 30a of the housing 30 by bolts 54, and the upper portion of the support 41 is connected to the rear surface 20c of the PCU 20 by bolts 53. A vibration-proof bush 42 is interposed between the upper part of the support portion 41 and the PCU 20. The rear bracket 40 is fixed to the housing 30 by four bolts 54 arranged in the vehicle width direction, and is connected to the PCU 20 by two separate bolts 53 arranged in the vehicle width direction. The rear bracket 40 is made by pressing a metal plate (steel plate). As described above, the anti-vibration bush 12 is also interposed between the upper part of the support portion 11 of the front bracket 10 and the PCU 20. The PCU 20 is supported with a gap between the housing 30 and the motor vibration transmitted to the PCU 20 via the housing 30 by sandwiching the anti-vibration bushes 12 and 42 between the brackets 10 and 40 and the PCU 20. And engine vibration is suppressed.

Ribs 45 extending in the vertical direction along the edge of the support portion 41 are provided on both sides of the support portion 41 of the rear bracket 40. The lower part of the rib 45 is curved along the edge of the base 43. Here, "both sides of the support portion 41" means both sides of the support portion 41 (that is, ends in the vehicle width direction) when viewed from the front (or rear) of the vehicle. The rib 45 is provided to increase the strength of the support portion 41 made of a metal plate. However, as described above, the overall strength of the rear bracket 40 is suppressed to such an extent that the support portion 41 bends under a predetermined collision load.

The base portion 43 is provided with an arch portion 44 that is curved when viewed from the front (or rear) of the vehicle. The arch portion 44 is formed so as to extend rearward from the boundary between the base portion 43 and the support portion 41. However, the rear end of the arch portion 44 is located in front of the fastening point (that is, the bolt 54) of the base portion 43 to the housing 30. In FIG. 4, the straight line L1 indicates the position of the rear end of the arch portion 44. The positional relationship between the rear end of the arch portion 44 and the bolt 54 will be described later with reference to FIG. The arch portion 44 is provided to secure a space penetrating in the front-rear direction between the lower surface of the base portion 43 and the upper surface 30a of the housing 30.

A power cable 24 passes between the upper surface 30a of the housing 30 and the arch portion 44 (see FIG. 4). That is, the arch portion 44 is provided to pass the power cable 24 in the front-rear direction of the vehicle between the upper surface 30a of the housing 30 and the base portion 43. The power cable 24 extends from the connector 23 provided on the rear surface 20c of the PCU 20 and passes under the arch portion 44. The tip of the power cable 24 is connected to an air conditioner (not shown). In the case of the hybrid vehicle 100, the air conditioner operates at a high voltage output by a high voltage battery that drives the traveling motor 3. The power of the high voltage battery is supplied to the PCU 20, and the power is supplied from the high voltage battery (not shown) to the air conditioner (not shown) via the PCU 20 and the power cable 24. Since high voltage power flows through the power cable 24, it is desirable to avoid damage to the power cable 24 when a vehicle collides.

Various electrical devices are mounted at high density in the front compartment, and multiple electrical devices are connected by power cables and communication cables. Therefore, cables can pass through various locations within the front compartment. In some cases, it may have to pass in the vicinity of the rear bracket 40 that supports the PCU 20. The power cable 24 is an example. The power cable 24 is passed under the arch portion 44. On the other hand, as described above, the support portion 41 of the rear bracket 40 bends backward when the vehicle collides forward (or diagonally forward). If the power cable 24 is involved in the bending and deformation of the support portion 41, an excessive load may be applied to the power cable 24. In some cases, the upper part of the support portion 41 may break. The fracture surface of the support portion 41 is sharp, and if the power cable 24 touches the fracture surface, the power cable 24 may be damaged. The arch portion 44 through which the power cable 24 is passed is provided to protect the power cable 24 from the deformed or broken support portion 41.

Next, the relationship between the deformation of the rear bracket at the time of collision and the arch portion 44 will be described. Hereinafter, the description will be continued with reference to FIGS. 5 and 6 together with FIG. FIG. 5 is an enlarged side view of the vicinity of the rear bracket 40. FIG. 6 is an enlarged side view of the rear bracket 40 deformed by receiving a collision load. In FIGS. 5 and 6, since the arch portion 44 is hidden by the rib 45, the arch portion 44 is shown by a broken line.

The broken line L1 shown in FIG. 5 indicates the rear end of the arch portion 44. The broken line L2 indicates the front end of the bolt head of the bolt 54. The bolt 54 corresponds to a fastening portion for fixing the base 43 to the housing 30. The rear end (dashed line L1) of the arch portion 44 is located in front of the vehicle with respect to the fastening portion (dashed line L2) for fastening the base portion 43 to the housing 30.

The front end of the arch portion 44 is located at the boundary between the base portion 43 and the support portion 41, and serves to increase the bending rigidity of the boundary between the base portion 43 and the support portion 41. By shortening the arch portion 44, it is possible to suppress an increase in bending rigidity at the boundary between the base portion 43 and the support portion 41. As a result, when a load is applied to the PCU 20 from the front, that is, when a load is applied to the support portion 41 of the rear bracket 40, bending deformation can occur at the boundary between the support portion 41 and the base portion 43. Assuming that the position of the bolt 53 fixing the support portion 41 to the PCU 30 is the load point with respect to the support portion 41, the distance from the load point (bolt 53) to the bending starting point (the boundary between the base portion 43 and the support portion 41) is , Distance B1 (see FIG. 6).

As a comparative example, enlarged side views of the rear bracket 140 of Patent Document 1 (Japanese Unexamined Patent Publication No. 2017-024466) are shown in FIGS. 7 and 8. Please refer to FIG. 9 for the detailed shape of the rear bracket 140.

The conventional rear bracket 140 is provided with an arch portion 144 at the boundary between the support portion 141 and the base portion 143. The arch portion 144 extends from the front end to the rear end of the base portion 143. As a result of providing the long arch portion 144, the bending rigidity of the boundary between the base portion 143 and the support portion 141 is increased. In the conventional rear bracket 140, the through hole 146 is provided in the rib 145 of the support portion 141, and the strength of the support portion 141 is lowered at the position of the through hole 146. When the PCU 30 receives a load from the front, the position of the through hole 146 of the rear bracket 140 becomes the starting point of bending deformation. The distance from the load point (bolt 53) to the bending start point (through hole 146) at this time is the distance B2 (see FIG. 8). The distance from the load point to the starting point of bending (distance B1 in FIG. 6, distance B2 in FIG. 8) is in the case of the rear bracket 40 (distance B1) this time rather than in the case of the conventional rear bracket 140 (distance B2). Becomes longer.

When the bolt 53 is a load point, the load received is represented by W1, the displacement amount of the load point in the direction parallel to the F axis is represented by dX, and the rigidity between the load W1 and the displacement amount dX is represented by K1. W1 = K1 × dX1. The rigidity K1 is proportional to the cube of the distance from the load point to the starting point of bending deformation (distance B1 in FIG. 6, distance B2 in FIG. 7). That is, by generating the starting point of bending deformation at the boundary between the base portion 43 and the support portion 41, the rigidity K1 at the load point (bolt 53) is lowered as compared with the conventional rear bracket 140. The load W applied to the PCU 20 is shared by the rear bracket 40 and the front bracket 10. By lowering the rigidity K1 of the rear bracket 40, the share of the front bracket 10 with respect to the load W applied to the PCU 20 increases, and the share of the rear bracket 40 decreases.

The advantages of the mounting structure 2 of the embodiment are summarized below. In the conventional rear bracket 140 (FIG. 9), a through hole 146 is provided in the support portion 141 to form a yielding portion. In the rear bracket 40 in the mounting structure 2 of the embodiment, the boundary between the base portion 43 and the support portion 41 corresponds to the yielding portion. Therefore, it is not necessary to provide a through hole in the rib of the support portion. The manufacturing process of the rear bracket is simplified accordingly.

The arch portion 44 of the rear bracket 40 is shorter than the arch portion 144 of FIG. Since the arch portion 44 is short, the material of the rear bracket 40 can be reduced, the material cost can be suppressed, and the weight can be reduced.

The points to be noted regarding the technique described in the examples will be described. It is also preferable to provide the arch portion 44 with a clamp for locking the power cable 24. The cable passing through the arch portion 44 may be a signal cable instead of a power cable. The PCU 20 is an example of a power control unit. In the embodiment, the technique of the present application has been described by taking the hybrid vehicle 100 as an example. The techniques disclosed herein are also preferably applied to electric vehicles and fuel cell vehicles. In the case of a fuel cell vehicle, the power control unit is a device that drives a driving motor using the electric power generated by the fuel cell.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above. The technical elements described herein or in the drawings exhibit their technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the techniques exemplified in the present specification or the drawings can achieve a plurality of purposes at the same time, and achieving one of the purposes itself has technical usefulness.

2: Mounting structure 3: Motor 4: Differential gear 6: Power distribution mechanism 10: Front bracket 11: Support portion 12, 42: Anti-vibration bush 13, 43: Base 20: Power control unit (PCU)
23: Connector 24: Power cable 30: Housing 40: Rear bracket 41: Support 44: Arch 45: Ribs 51, 52, 53, 54: Bolt 90: Front compartment 98: Engine 100: Hybrid vehicle

Claims (2)

It is a structure mounted on the front compartment of the power control unit that drives the driving motor.
The front and rear of the power control unit are supported by front brackets and rear brackets, and the power control unit is fixed with a gap above the housing for accommodating the motor.
The rear bracket comprises a base fixed to the housing and a support extending from the front end of the base to the power control unit.
The base includes an arch for passing cables to and from the housing in the front-rear direction of the vehicle.
A mounting structure of a power control unit in which the rear end of the arch portion in the vehicle front-rear direction is located in front of the vehicle from the fastening point where the base portion is fastened to the housing. The mounting structure according to claim 1, wherein the cable is a power cable that transmits output power of a power source for driving the motor.

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