Fastening structure of components installed in electric vehicles

Abstract

To provide a fastening structure that can prevent bolt damage during a frontal collision. [Solution] This fastening structure fastens a connector shell 3 adjacent to a PCU case 1 and a PCU upper cover 2, wherein the PCU upper cover 2 is fastened to the PCU case 1, and the connector shell 3 is provided with a fastening portion 4 consisting of a bolt 41 and an insertion hole 42. When fastening the connector shell 3 to the front end 13 of the PCU case 1 via the fastening portion 4, the front end face 23 of the PCU upper cover 2 and the first rear end face 33 of the connector shell 3 are positioned opposite each other with a first gap b between them, and the gap a between the bolt 41 and the insertion hole 42 in the fastening portion 4 of the connector shell 3 is made larger than the first gap b. This is a fastening structure for a component mounted on an electric vehicle.

Description

Technical Field

[0001] The present invention relates to a fastening structure for a member mounted on an electric vehicle, and for example, relates to a fastening structure for a case that houses a motor control unit (power control unit).

Background Art

[0002] Conventionally, a vehicle is provided with an underrun protector device that prevents intrusion into the lower part of the vehicle when a passenger car or the like collides with the vehicle (see Patent Document 1). On the other hand, in an electric vehicle, a power control unit (hereinafter sometimes referred to as a PCU) that controls a motor for vehicle travel is fixed on a transaxle case (hereinafter sometimes referred to as a TA case) and mounted in the front compartment of the vehicle. Therefore, a mounting structure for protecting the PCU and the like from the impact during a frontal collision has been proposed.

[0003] In Patent Document 2, there is a mounting structure in which a motor control unit (corresponding to a PCU) that controls a motor for vehicle travel is fixed on a motor case (corresponding to a TA case). The mounting structure includes a front bracket that supports the front side of the vehicle of the motor control unit and a rear bracket that supports the rear side of the vehicle of the motor control unit. The rear bracket is attached to the attachment surface of the motor case by a first fastening member disposed on the front side of the vehicle and a second fastening member disposed on the rear side of the vehicle. The rear bracket is formed with a first insertion hole into which the first fastening member is inserted and a second insertion hole into which the second fastening member is inserted, and the gap between the second fastening member and the second insertion hole is larger than the gap between the first fastening member and the first insertion hole.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] According to the motor control unit mounting structure described in Patent Document 2, the gap between the fastening member and the insertion hole on the first fastening part side is small, but this part is thick and has high mechanical strength. On the other hand, the gap between the fastening member and the insertion hole on the second fastening part side is large. If a frontal collision occurs, the PCU moves rearward relative to the TA case, and along with the deformation of the rear bracket, the fastening part is dragged towards the rear of the vehicle. As a result, the impact load is applied to the first fastening part side, which has a small gap, and not to the second fastening member side, which has a large gap. In other words, the structure is such that the impact load is received by the part with high mechanical strength. However, in Patent Document 2, the impact load is concentrated as a shear load on the first fastening part, so even though it has high strength, the first fastening member (bolt) may break due to stress concentration. When the bolt breaks at this time, it may damage surrounding devices. In particular, damage to electrical systems such as high-voltage connectors may cause short circuits.

[0006] The present invention has been made in view of the above technical problems, and the object of the present invention is to provide a fastening structure for a member mounted on an electric vehicle that can prevent damage to the fastening member in the event of a frontal collision, in a structure in which a member mounted on an electric vehicle is fastened to this member with a fastening member (bolt). [Means for solving the problem]

[0007] To achieve the above objective, the present invention provides a fastening structure for a member mounted on an electric vehicle, wherein a third member is fastened adjacent to a first member and a second member, the first member being integrated with the second member, the third member comprising a fastening portion consisting of a fastening member and an insertion hole, and a first rear end face, the front end face of the second member and the first rear end face of the third member being positioned opposite each other with a first gap between them, and the third member being fastened to the front end of the first member via the fastening portion, characterized in that the gap between the fastening member and the insertion hole in the fastening portion of the third member is greater than the first gap.

[0008] In the fastening structure for a member mounted on an electric vehicle of the present invention, the third member further comprises a portion which becomes a second rear end face, and the front end face of the first member and the second rear end face of the third member are arranged opposite each other with a second gap between them, and it is preferable that the gap between the fastening member and the insertion hole in the fastening portion of the third member is greater than the second gap.

[0009] In the fastening structure for components mounted on an electric vehicle according to the present invention, the first component may be a PCU case housing a power control unit for controlling a motor for vehicle operation, the second component may be a PCU upper cover, and the third component may be a connector shell.

[0010] In the fastening structure for a component mounted on an electric vehicle of the present invention, the connector shell can be composed of an upper shell having a first rear end face and a lower shell having a fastening portion for fastening to the upper shell and a second rear end face. [Effects of the Invention]

[0011] The present invention provides a fastening structure for components mounted on an electric vehicle, which fastens a first component (e.g., a PCU case) and a second component (e.g., an upper cover) mounted in the front compartment of the electric vehicle, and a third component (e.g., a connector shell) adjacent to them. The second component is integrated into the first component, and the third component, which is closest to the front collision side, is fastened to the front end of the first component by a fastening portion consisting of a fastening member (bolt) and an insertion hole. Here, the distance between the fastening member and the through hole in the third component is greater than the distance between the second component and the third component. With this configuration, the third component moves to the rear of the vehicle due to the impact of a front collision, so the second component and the third component, which are spaced close together, collide, and the collision between the relatively high-strength components is avoided as the collision between the fastening member and the through hole, which are spaced far apart, is avoided. By providing a high-strength part that preferentially collides during a front collision in this way, shear force can be prevented from being applied to the fastening member (bolt).

[0012] Furthermore, by adding a configuration in which the distance between the fastening member and the through hole in the third member is greater than the distance between the first and third members, collisions occur not only between the second and third members, but also between the first and third members. By adding these collision points, the load transmission paths are increased and the impact force can be dispersed. Therefore, the stress (shear stress) on the fastening member can be further reduced. As described above, the present invention provides a fastening structure for components mounted on an electric vehicle that can prevent damage to fastening members such as bolts in the event of a frontal collision. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing the appearance when the fastening structure of the present invention is applied to a power control unit. [Figure 2] This is a schematic diagram illustrating one embodiment of the fastening structure of the present invention, showing the state before and after a frontal collision. [Figure 3]This schematic diagram illustrates another embodiment of the fastening structure of the present invention, showing the state before and after a frontal collision. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are merely examples of how the present invention can be implemented and do not limit the invention.

[0015] The fastening structure for components mounted on an electric vehicle according to the present invention can be applied, for example, to a hybrid vehicle equipped with both a motor and an engine for vehicle propulsion. In addition to the engine, the front compartment of the vehicle is equipped with a power control unit (hereinafter abbreviated as PCU) and a transaxle case (hereinafter abbreviated as TA case), as well as various other devices such as a sub-battery, relay box, air conditioner, and radiator. These devices correspond to the components mounted on the electric vehicle used in the present invention. In this embodiment, the structure for fastening the PCU case and the components attached to this case will be described as an example. Of course, it can also be applied to fastening structures between components in TA cases other than the PCU case, battery cases, etc.

[0016] Figure 1 is a schematic diagram illustrating a fastening structure to which the present invention is applied to a PCU, where (a) shows the external appearance of the PCU, and (b) is a top view of the PCU case 1, showing the case in which a connector shell 3 is to be fastened next to the PCU upper cover 2. The PCU10 is a power converter that boosts the power from the high-voltage battery, converts it to AC, and supplies it to the motor. It incorporates a voltage converter circuit and an inverter circuit to control the motor. These devices are housed in an aluminum die-cast PCU case 1 and covered by an aluminum die-cast PCU upper cover 2 (bolts and other fastening parts are not shown, and the same applies below). The TA case is also made of aluminum die-cast and houses the motor, a power distribution mechanism that combines and distributes the output torque of the engine and the motor, and a differential gear. The PCU case is integrally fastened on top of the TA case.

[0017] As shown in the top view of Figure 1(b), the PCU upper cover 2 is fastened to the top of the PCU case 1 with bolts or the like, making it an integrated unit. In this example, the PCU case 1 has an outer edge portion 12 that protrudes outward from the PCU upper cover 2. This outer edge portion 12 is located towards the front of the vehicle. A connection port 50 for a high-voltage connector 5 called a PN connector is formed on this outer edge portion 12. The connection port 50 is covered by a connector shell 3 to protect the high-voltage connector 5. In the event of a frontal collision, an impact load is applied to the outer edge portion 12, so the connector shell 3 is made of a strong material with sufficient strength. In this example, a lightweight and relatively strong aluminum die-cast upper shell 31 is used. In Figure 1(b), the arrows indicate how the upper shell 31 is fastened to cover the connection port 50. Furthermore, connection ports (not shown) for other power cables and harnesses are formed on the outer edge 12 of the PCU case 1, and these are also covered with similar connector shells.

[0018] Figure 2 schematically shows a cross-section of the area around section A in Figure 1, with (a) showing the state before the frontal collision and (b) showing the state after the frontal collision. First, the PCU case 1 (corresponding to the first member of the present invention) and the PCU upper cover 2 (corresponding to the second member of the present invention) are fastened with bolts or the like, and the two members are integrated. A structure for fastening a connector shell 3 (corresponding to the third member of the present invention) adjacent to the PCU upper cover 2 is shown. Here, as the connector shell 3, the upper shell 31 is used as described above, and the upper shell 31 is provided with a fastening portion 4 including a bolt 41 and a through hole 42. Therefore, the upper shell 31 is fastened and fixed to the front end portion 13 (corresponding to the front end portion of the first member of the present invention) of the PCU case 1 using this fastening portion 4. Note that the fastening portion may use a bolt-nut member, a screw member, or the like, and the type and form of the fastening component are not limited.

[0019] Here, when fastening the upper shell 31 to the front end portion 13 of the PCU case 1, it is important to arrange them to face each other with a gap b between the front end face 23 of the PCU upper cover 2 (corresponding to the front end face of the second member of the present invention) and the rear end face 33 of the upper shell 31 (corresponding to the first rear end face of the third member of the present invention), and at this time, the distance a between the bolt 41 and the through hole 42 of the fastening portion of the upper shell 31 is made larger than the gap b. Specifically, the distance a is the distance between the outer surface of the bolt 41 and the inner surface of the through hole 42, which can be said to be the shortest contact distance between the two (the same applies to the following embodiments). Note that in order to make the distance a larger, it is easy to form the through hole 42 as an elongated hole.

[0020] With such a configuration, in the event of a frontal collision, a collision load (input load) is applied to the upper shell 31. As shown in Fig. 2(b), the upper shell 31 moves toward the rear side (rear side) of the vehicle, reducing the gap b until the PCU upper cover 2 and the upper shell 31 collide C1 (the gap becomes zero). However, at this time, there is still a margin between the bolt 41 and the through-hole 42 (maintaining the gap a'), and the collision is avoided. Therefore, bolt breakage is avoided, and damage to internal PN connectors, etc., can also be avoided. Also, both the PCU upper cover 2 and the upper shell 31 are made of aluminum die-cast, which are lightweight and have sufficient strength. As a result, they are resistant to impact loads and do not lead to significant damage to other surrounding parts.

[0021] Next, Fig. 3 is a schematic diagram showing another embodiment. Similar to Fig. 2, (a) shows the state before a frontal collision, and (b) shows the state after a frontal collision. In this example, the connector shell 3 is composed of an upper upper shell 31 and a lower lower shell 32. The lower shell 32 has a substantially L shape and has a collision wall 35 at the rear (rear side), and a fastening portion 40 composed of a bolt 43 and a through-hole 44 at the front (front side). The lower shell 32 is made of the same aluminum die-cast strength member as the upper shell 31. Thus, this embodiment is formed by further fastening and fixing the lower shell 32 to the upper shell 31 shown in the embodiment of Fig. 2 described above. Here, the important points are to arrange them facing each other with a gap c between the front end face 14 of the PCU case 1 (corresponding to the front end face of the first member of the present invention) and the end face 34 of the collision wall 35 of the lower shell 32 (corresponding to the second rear end face of the third member of the present invention), and in this example, the gap a between the bolt 41 and the through-hole 42 of the fastening portion of the upper shell 31 described above is set to be larger than the gap c. Conversely, the gap c can be set, for example, to the same distance as the gap b so that the gap c is smaller than the gap a.

[0022] With this configuration, in the event of a frontal collision, the collision load (input load) is applied to the upper shell 31, causing the upper shell 31, along with the lower shell 32, to move towards the rear of the vehicle (rear side) as shown in Figure 3(b). As a result, the gap b is reduced, and the PCU upper cover 2 and the upper shell 31 collide C1 (the gap becomes 0). At the same time, the gap c is also reduced, causing the front end face 14 of the PCU case 1 and the end face 14 of the lower shell 32 to collide C2 (the gap becomes 0). However, as in Figure 2, there is still sufficient space a between the bolt 41 and the through hole 42 (the gap a' is maintained), and the collision is avoided. Therefore, bolt damage is avoided, and damage to the internal PN connector, etc., can also be avoided. Furthermore, since the lower shell 32, in addition to the PCU upper cover 2 and upper shell 31, is also made of die-cast aluminum and has high strength, the pressure load resistance is even higher. Moreover, in this example, the number of collision points has increased to two, increasing the load transmission path. Therefore, the impact force can be dispersed, and the shear stress on the bolt can be further reduced.

[0023] According to the above embodiment, the components mounted on the electric vehicle are the same as in the conventional PCU case, PCU upper cover, and connector shell (upper shell and lower shell), and are not reinforced by providing separate protector members or the like. By improving the arrangement and fastening structure of the mounted components that have been used in the conventional manner, the movement of the components (connector shell) due to the impact of a frontal collision is utilized to preferentially cause collisions between strength components, thereby preventing damage to bolts and preventing damage to other surrounding components. Furthermore, it has been confirmed that the pressure resistance load is the same as when a protector member is provided.

[0024] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above and can be implemented with appropriate modifications as needed. For example, the fastening structure of the present invention is not limited to PCU cases, but can be applied to various devices such as battery cases, inverter cases, and converter cases. Furthermore, these cases are not limited to aluminum die-cast, but can be any strong material having a predetermined strength. In addition, the strength can be increased by appropriately increasing the thickness of the collision wall of the lower shell. Moreover, although hybrid vehicles were used as an example in this embodiment, it is also possible to apply it to electric vehicles and fuel cell vehicles. [Explanation of symbols]

[0025] 1: PCU case 2: PCU Upper Cover 3: Connector shell 4, 40: Fastening part 5: High-voltage connector (PN connector) 10: PCU 12: Outer edge 13: Front end of the PCU case 14: Front end face of the PCU case 23: Front end face of PCU upper cover 31: Upper Shell 32: Roashell 33: Rear end face of the upper shell 34: End face of the impact wall of the lower shell 35: Lower Shell Collision Wall 41, 43: Bolt 42, 44: Through hole (long hole)

Claims

1. A fastening structure for components mounted on an electric vehicle, wherein a third component is fastened adjacent to a first component and a second component, The first member has the second member integrated into it, and the third member has a fastening portion consisting of a fastening member and an insertion hole and a first rear end face. The front end face of the second member and the first rear end face of the third member are positioned opposite each other with a first gap between them, and the third member is fastened to the front end of the first member via the fastening portion. A fastening structure for a member mounted on an electric vehicle, characterized in that the distance between the fastening member and the insertion hole in the fastening portion of the third member is greater than the distance between the first member and the third member.

2. A fastening structure for a component mounted on an electric vehicle according to claim 1, The third member further comprises a portion which becomes the second rear end face, The front end face of the first member and the second rear end face of the third member are arranged facing each other with a second gap between them. A fastening structure for a member mounted on an electric vehicle, characterized in that the distance between the fastening member and the insertion hole in the fastening portion of the third member is greater than the distance between the second member and the third member.

3. A fastening structure for a member mounted on an electric vehicle according to claim 1 or 2, The first component is a PCU case housing a power control unit that controls the motor for vehicle driving. The second component is the PCU upper cover. A fastening structure for components mounted on an electric vehicle, characterized in that the third component is a connector shell.

4. A fastening structure for a component mounted on an electric vehicle according to claim 3, The connector shell is characterized by comprising an upper shell having a first rear end face and a lower shell having a fastening portion for fastening to the upper shell and a second rear end face, thus providing a fastening structure for a component mounted on an electric vehicle.

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