JP2019111837A - Loading structure of power control unit - Google Patents

Abstract

The technology disclosed herein relates to an improvement of a rear bracket in a mounting structure for supporting a power control unit above a housing containing a motor.
A housing (30) and a PCU (20) for driving a motor are mounted on a front compartment of a vehicle. The PCU 20 is supported at its front and rear by a front bracket 10 and a rear bracket 40. 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 base 43 includes an arch portion 44 passing the power cable 24 in the vehicle longitudinal direction between the base portion 43 and the housing 30. The rear end of the arch portion 44 is located forward of a fastening portion (bolt 54) for fastening the base 43 to the housing 30.
[Selected figure] Figure 4

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 a power control unit to a front compartment. In the technique disclosed in Patent Document 1, the power control unit is supported by front and rear brackets at the front and rear thereof, and is fixed with a gap above the housing accommodating the motor. The gap between the power control unit and the housing is secured by the front bracket and the rear bracket in order to suppress the vibration of the motor transmitted to the power control unit through the housing. In the following, for convenience of the description, 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 front and rear brackets, it may be written as "both brackets".

  Connected to the power control unit is a power cable that transmits power of several tens of kilowatts or more. In the mounting structure of Patent Document 1, the rear bracket includes a base fixed to the housing, and a support that extends from the base and supports the power control unit. The base is provided with an arch portion through which the power cable passes in the vehicle longitudinal direction between the housing and the housing. Furthermore, the support part is provided with a yielding part above the base. When a vehicle collides, the power control unit supported with a gap between itself and the housing may move backward from the front under load. When a load greater than a predetermined load is applied to the rear bracket, the yield portion first yields and the support portion is bent backward. As the support bends above the arch, cables passing under the arch will not be caught in the deformation of the rear bracket.

  FIG. 9 shows a rear bracket 140 disclosed in Patent Document 1. FIG. 9 shows the rear of the power control unit 20 and the rear bracket 140 as viewed obliquely from the rear. The power control unit 20 is supported by a rear bracket 140 and a front bracket (not shown) with a gap between it and the top surface 30 a of the housing 30. The connector 23 of the power cable 24 is connected to the rear surface 20 c 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 between the housing 30 and through which the power cable 24 passes in the longitudinal direction of the vehicle. In addition, ribs 145 are provided at both ends of the support portion 141, and a through hole 146 is provided substantially at the center of the rib 145 in the vertical direction. The through hole 146 corresponds to the above-described yielding portion. In the event of a collision, when the power control unit 20 receives a load from the front, the support portion 141 is bent at the location of the through hole 146 whose strength (rigidity) is low, and the impact of the collision is alleviated.

JP, 2017-024466, A

  The technology disclosed in the present specification relates to the improvement of the rear bracket in the mounting structure of Patent Document 1 in terms of weight reduction, manufacturability, and the like.

  This specification discloses a mounting structure of a power control unit for driving a motor for traveling to a front compartment. The power control unit is fixed with a gap above the housing that accommodates the motor, with the front and rear brackets supported by the power control unit. 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 portion passing the cable in the vehicle longitudinal direction between the base and the housing. The rear end of the arch portion in the vehicle longitudinal direction is located forward of the fastening point at which 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 143. In other words, the arch portion 144 extends further to the rear than the bolt 54 (fastening portion) fixing the base 143 to the housing 30. The arch portion 144 acts to increase the strength in the vicinity of the boundary between the base portion 143 and the support portion 141, so the long arch portion 144 significantly enhances the strength in the vicinity of the boundary between the base portion 143 and the support portion 141. In the conventional rear bracket 140, at the time 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 reduces the collision load applied to the power control unit 20 from the front. An arch 144 extends to the rear end of the base and protects the power cable 24 passing underneath. On the other hand, in the mounting structure disclosed in the present specification, the length in the front-rear direction of the arch portion is shortened, and the rigidity near the boundary between the base of the rear bracket and the support portion is reduced. That is, in the rear bracket 140 of Patent Document 1, the yield portion (through hole 146) is disposed above the arch portion 144, whereas in the rear bracket disclosed in this specification, the vicinity of the boundary between the base and the support portion is It corresponds to the yielding part. Since the arch part becomes short, it leads to weight reduction. Further, since the through holes 146 need not be provided, the manufacturing process can be simplified. Further, since the rigidity of the rear bracket is reduced, the sharing ratio of the rear bracket can be lowered in the sharing ratio of the collision load by both brackets.

  The details and further improvement of the technology disclosed in the present specification will be described in the following "Forms for Carrying Out the Invention".

It is a perspective view which shows an example of the components layout in a front compartment. It is a side view of a housing and PCU (power control unit). It is a perspective view of a rear bracket. It is the figure which saw the rear bracket and PCU from diagonally back. It is an enlarged side view near a rear bracket. FIG. 6 is an enlarged side view of the vicinity of a 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 from diagonally back.

  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 provided with both a motor 3 for traveling and an engine 98. The hybrid vehicle 100 mounts an engine 98, a motor 3, and a power control unit 20 for driving the motor 3 in a front compartment 90 of the vehicle. In the front compartment 90, the power control unit 20 is fixed on the housing 30. The housing 30 accommodates the motor 3, the power distribution mechanism 6, and the differential gear 4. In the following, the “power control unit 20” is abbreviated as “PCU 20” to simplify the description. PCU is an abbreviation of Power Control Unit.

  The arrangement of devices in the front compartment 90 is shown in FIG. In the front compartment 90, the engine 98, the PCU 20, and the housing 30 are mounted. In addition to these devices, various devices such as a battery 95 are disposed, but the description thereof is omitted. It should be noted that the housing 30 and the engine 98 are schematically illustrated in FIG. 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 (the left side of the vehicle). The meaning of the symbols of the coordinate system is the same in the following figures. Also, in the following, expressions such as “front”, “rear”, “front”, “rear”, etc. are used for components mounted in the front compartment 90, but “front” in these expressions is the vehicle front side Means “rear” means the rear side of the vehicle.

  As described above, in addition to the motor 3, the power distribution mechanism 6 and the differential gear 4 are accommodated in the housing 30. 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 according to the situation. Since the differential gear 4 is built in, the housing 30 is, in other words, a case of a motor and a transaxle. The housing 30 is made, for example, by die-casting or cutting out of aluminum.

  The engine 98 and the housing 30 are connected 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 secure the structural strength of the vehicle. Although only one side member 96 is shown in FIG. 1, another side member extends also to the lower left of the engine 98 in FIG. The engine 98 and the housing 30 are suspended between 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 an alternating current, and supplies it to the motor 3. The PCU 20 may also convert AC power generated by the motor 3 into DC power and may further step down. The stepped down power charges the high voltage battery.

  Although the details will be described later, in the mounting structure 2 of the embodiment, the PCU 20 is supported with a gap between itself and the top surface of the housing 30. The front side of the PCU 20 is supported by the front bracket 10, and the rear side 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. 2 together with FIG. FIG. 2 is a side view of the PCU 20 and the housing 30. The “side surface” is a view as viewed from the vehicle width direction (H-axis direction in the drawing).

  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 power from the PCU 20 to the motor 3. Although the description is omitted, the housing 30 accommodates two three-phase AC motors, and the six power cables 21 transmit two sets of three-phase AC. Reference numeral 31 denotes a power cable terminal provided on the upper surface 30 a of the housing 30. Although two motors are accommodated in the housing 30, in the following, description will be continued focusing on one of the motors (motor 3).

  As described above, the motor 30, the power distribution mechanism 6, and the differential gear 4 are accommodated in the housing 30. In the housing 30, the output shaft 3a of the motor 3, the main shaft 6a of the power distribution mechanism 6, and the main shaft 4a of the differential gear 4 are arranged in parallel. These three axes extend in the vehicle width direction. As shown in FIG. 2, the three axes are arranged to form a triangle when viewed in the vehicle width direction. Due to the above arrangement of the three axes, 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 inclined downward.

  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 20 a of the PCU 20, and the rear bracket 40 supports the rear surface 20 c of the PCU 20. A gap SP is secured between the lower surface 20 b of the PCU 20 and the upper surface 30 a of the housing 30. The 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 mentioned above, the rear end of the base 13 of the front bracket 10 means the end on the vehicle rear side of the base 13 fixed on the housing 30.

  The base 13 of the front bracket 10 is fixed to the upper surface 30 a of the housing 30 by bolts 52, and the upper portion of the support 11 is connected to the front surface 20 a of the PCU 20 by bolts 51. The antivibration 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 aligned in the vehicle width direction and connected to the PCU 20 by two other bolts aligned 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 end on the vehicle front side of the base 43 fixed on the housing 30.

  The arrow W in FIG. 2 schematically indicates the collision load that the PCU 20 receives when the hybrid vehicle 100 makes a frontal collision (or a diagonal frontal collision). When the PCU 20 receives a large collision load W from the front, the support portion 11 of the front bracket 10 and the support portion 41 of the rear bracket 40 both bend backward. The rigidity of the front bracket 10 and the rear bracket 40 is suppressed to a size that causes bending when receiving a collision load W of a predetermined size or more. This is because if the rigidity of the front bracket 10 and the rear bracket 40 is too high, damage due to the collision load W that the PCU 20 receives can not 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 portions of the base portions 13, 43 and the housing 30 is also alleviated. Further, it is desirable that the bending stiffness of the front bracket 10 about the axis parallel to the H axis of the coordinate system in the figure and the bending stiffness of the rear bracket 40 be equal. If the bending stiffness is different, the load sharing becomes 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 the PCU 20 and the rear bracket 40 viewed obliquely from the rear. In FIG. 4, the PCU 20 is drawn in phantom lines to aid understanding. In FIG. 4, a part of the housing 30 for fixing the rear bracket 40 is also drawn by an imaginary line. The rear bracket 40 is formed by pressing a metal plate. The base 43 of the rear bracket 40 is fixed to the upper surface 30 a of the housing 30 by a bolt 54, and the upper portion of the support 41 is connected to the rear surface 20 c of the PCU 20 by a bolt 53. An antivibration bush 42 is interposed between the upper portion of the support portion 41 and the PCU 20. The rear bracket 40 is fixed to the housing 30 by four bolts 54 aligned in the vehicle width direction, and is connected to the PCU 20 by two other bolts 53 aligned 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 portion of the support portion 11 of the front bracket 10 and the PCU 20. The PCU 20 is supported with a gap between it and the housing 30, and by sandwiching the anti-vibration bushes 12, 42 between the brackets 10, 40 and the PCU 20, the motor vibration transmitted to the PCU 20 through the housing 30 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 portion of the rib 45 is curved along the edge of the base 43. Here, “both sides of the support portion 41” means both sides (that is, ends in the vehicle width direction) of the support portion 41 when viewed from the front (or rear) of the vehicle. The ribs 45 are 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 a size that allows the support portion 41 to bend under a predetermined collision load.

  The base portion 43 is provided with an arch portion 44 which is curved as viewed from the front (or rear) of the vehicle. The arch portion 44 is formed 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 forward of the fastening point of the base 43 to the housing 30 (i.e., the bolt 54). In FIG. 4, a 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 again with reference to FIG. 5 later. The arch portion 44 is provided between the lower surface of the base 43 and the upper surface 30 a of the housing 30 in order to secure a space penetrating in the front-rear direction.

  A power cable 24 passes between the top surface 30a of the housing 30 and the arch portion 44 (see FIG. 4). That is, the arch portion 44 is provided between the upper surface 30 a of the housing 30 and the base portion 43 in order to pass the power cable 24 in the vehicle longitudinal direction. The power cable 24 extends from the connector 23 provided on the rear surface 20 c of the PCU 20 and passes under the arch portion 44. The end 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 from a high voltage battery that drives the driving 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 that damage to the power cable 24 in the event of a vehicle collision can be avoided.

  In the front compartment, various electrical devices are mounted at high density, and a plurality of electrical devices are connected by power cables and communication cables. Therefore, cables can pass through various places in the front compartment. In some cases, it may also be necessary to pass near 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 is bent backward when the vehicle makes a frontal collision (or a diagonal frontal collision). If the power cable 24 is caught in the bending deformation of the support portion 41, an excessive load may be applied to the power cable 24. In some cases, the upper side of the support portion 41 may be broken. The fractured surface of the support portion 41 is sharp, and the power cable 24 may be damaged if the power cable 24 touches it. An arch 44 through which the power cable 24 passes is provided to protect the power cable 24 from the deformed or broken support 41.

  Next, the relationship between the deformation of the rear bracket at the time of a collision and the arch portion 44 will be described. 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 due to the 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.

  A 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 (broken line L1) of the arch portion 44 is located forward of the fastening portion (broken line L2) for fastening the base 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 of 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 be generated 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 a load point on the support portion 41, the distance from the load point (bolt 53) to the bending start point (boundary between the base 43 and the support portion 41) is , Distance B1 (see FIG. 6).

  An enlarged side view of the rear bracket 140 of Patent Document 1 (Japanese Patent Application Laid-Open No. 2017-024466) as a comparative example is shown in FIGS. 7 and 8. For the detailed shape of the rear bracket 140, refer to FIG.

  The conventional rear bracket 140 includes 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 of the base portion 143 to the rear end. 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 low at the location 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 the bending deformation. The distance from the load point (bolt 53) at this time to the bending start point (through hole 146) is a 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 current rear bracket 40 (distance B1) than in the case of the conventional rear bracket 140 (distance B2). Will be longer.

  Assuming that the bolt 53 is a load point, the received load is represented by W1, the displacement in the direction parallel to the F axis of the load point is represented by dX, and the rigidity between the load W1 and the displacement dX is represented by K1 as W1 = K1 × dX1. The rigidity K1 is proportional to the cube of the distance from the load point to the starting point of the bending deformation (the distance B1 in FIG. 6, the distance B2 in FIG. 7). That is, by causing the starting point of the 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 reduced compared to 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 reducing the rigidity K1 of the rear bracket 40, the sharing ratio of the front bracket 10 to the load W applied to the PCU 20 increases, and the sharing ratio 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 a yield portion. Therefore, it is not necessary to provide a through hole in the rib of the support portion. Accordingly, the manufacturing process of the rear bracket is simplified.

  The arch portion 44 of the rear bracket 40 is short as compared to 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 reduced, and the weight can be reduced.

  Points to note regarding the technology described in the embodiment 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 44 may be a signal cable rather than a power cable. The PCU 20 is an example of a power control unit. In the embodiments, the technology of the present application has been described using 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 power generated by the fuel cell.

  As mentioned above, although the specific example of this invention was described in detail, these are only an illustration and do not limit a claim. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above. The technical elements described in the present specification or the drawings exhibit technical usefulness singly or in various combinations, and are not limited to the combinations described in the claims at the time of application. In addition, the techniques exemplified in the present specification or the drawings can simultaneously achieve a plurality of purposes, and achieving one of the purposes itself has technical utility.

2: Mounting structure 3: Motor 4: Differential gear 6: Power distribution mechanism 10: Front bracket 11: Support portion 12, 42: Vibration proof bush 13, 43: Base 20: Power control unit (PCU)
23: connector 24: power cable 30: housing 40: rear bracket 41: support portion 44: arch portion 45: ribs 51, 52, 53, 54: bolt 90: front compartment 98: engine 100: hybrid vehicle

Claims (1)

The mounting structure of the power control unit that drives the motor for traveling to the front compartment,
The power control unit is fixed with a gap above the housing that accommodates the motor while the front and rear of the power control unit is supported by the front bracket and the rear bracket.
The rear bracket includes 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 portion for passing a cable in a vehicle longitudinal direction between the base and the housing.
The power control unit mounting structure, wherein a rear end of the arch portion in the vehicle longitudinal direction is located forward of a fastening point at which the base is fastened to the housing.

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