Front structure of electric vehicle

Abstract

The design allows the front structure of an electric vehicle to deform in an intended mode when subjected to an impact load, thereby effectively absorbing impact energy. [Solution] The front structure of the electric vehicle comprises a front side member 10 and a motor frame 45 that supports the drive unit 1. A portion of the front side member 10 is positioned to overlap the drive mount 1 when viewed from the side. The inner portion of the front side member 10, located outside the drive unit 1, has a weak portion 25 that is less rigid than the outer portion. The weak portion 25 is configured to bend outward when a load is applied to the front of the front side member 10.

Description

Technical Field

[0001] The present invention relates to a front structure of an electric vehicle.

Background Art

[0002] When the front part of a vehicle receives an impact load caused by, for example, a frontal collision, it has a mechanism for absorbing the impact energy generated by the impact load. As a structure for absorbing the impact energy caused by an impact load, for example, as disclosed in Patent Document 1, a structure in which a fragile part is provided in a member constituting the front part of a vehicle body is known.

[0003] The structure disclosed in Patent Document 1 has a front side frame arranged on both sides in the vehicle width direction in the front part of the vehicle and a sub-frame arranged below the front side frame. A first fragile part is provided in the front side frame, and a second fragile part is provided in the sub-frame. The first fragile part provided in the front side frame has a concave part, and when receiving an impact load, the concave part is deformed so as to bend inward in the vehicle width direction. In addition, the second fragile part provided in the sub-frame is deformed so as to bend downward when receiving an impact load.

[0004] Thus, in the structure of the above example, when an impact load is input to, for example, a bumper in the front part of the vehicle, the first and second fragile parts are deformed to stably absorb the impact energy caused by the impact load.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] For example, in an electric vehicle, an electric motor is located at the front of the vehicle, and multiple electrical components and harnesses are arranged around the electric motor. High voltage acts on the harness connected to the battery pack. Therefore, it is preferable to have a predetermined gap between the electrical components and harness and the members arranged around them.

[0007] However, in the structure of the example above, the first weak point provided on the front side frame deforms inward in the vehicle width direction, and the first weak point is configured to be pressed against the outer surface of the power source (engine). As a result, there is a possibility that the first weak point will come into contact with electrical components and harnesses. This contact may prevent the first weak point from deforming sufficiently.

[0008] Furthermore, in a structure like the example above, where each of the multiple members constituting the front of the vehicle body has a weak point, when subjected to an impact load, each weak point may not deform in the intended deformation mode. For example, depending on the direction in which the impact load acts, unintended load transmission may occur to the front side frame and subframe, resulting in only one of the first and second weak points deforming. In such cases, it may become difficult to absorb the impact as intended.

[0009] Therefore, in the structure of the example above, there was room for improvement in attempting to deform the components constituting the front of the vehicle in the intended deformation mode in order to absorb the impact energy generated by the impact load when an impact load such as a frontal collision acts on the front structure of the vehicle.

[0010] The present invention was made to solve the above problems, and its objective is to provide a front structure for an electric vehicle that, when an impact load is applied to the front structure of the electric vehicle, can deform the front structure in an intended deformation mode and effectively absorb impact energy. [Means for solving the problem]

[0011] To achieve the above objective, the front structure of an electric vehicle according to the present invention comprises side members arranged on both sides in the vehicle width direction at the front of the vehicle and extending in the vehicle longitudinal direction, and a motor frame arranged on the lower side of the side members and supporting a drive unit including an electric motor. In the front structure of the electric vehicle, the side members and the drive unit are arranged to overlap when viewed from the side, and the side member located on the outer side of the drive unit in the vehicle width direction is provided with a weak portion that can bend outward in the vehicle width direction when a load acting in the vehicle longitudinal direction acts on the side member. [Effects of the Invention]

[0012] According to the present invention, when an impact load is applied to the front structure of an electric vehicle, the front structure can be deformed in an intended deformation mode, thereby effectively absorbing the impact energy. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic perspective view showing one embodiment of the front structure of an electric vehicle according to the present invention. [Figure 2] Figure 1 is a schematic side view of the left front side member, seen from the inside in the vehicle width direction. [Figure 3] Figure 2 is a top view of the front side member. [Figure 4] Figure 2 is a schematic perspective view showing the front side member with the inner component removed. [Figure 5] Figure 2 is a schematic side view of the front side member, etc., as seen from the outside in the vehicle width direction. [Figure 6] Figure 2 is a schematic perspective view of the front side members, etc., as seen from below. [Figure 7] Figure 1 is a bottom view of the left front side member and its surrounding area, seen from below the vehicle. [Figure 8] This is an end view showing the end face in the direction of arrow AA in Figure 4, with the front inner member visible. [Modes for carrying out the invention]

[0014] Hereinafter, embodiments of the front structure of an electric vehicle according to the present invention will be described with reference to the drawings (Figures 1 to 8). In the figures, the direction of arrow Fr indicates the front in the longitudinal direction of the vehicle. In the description of the embodiments, "front (front end) and rear (rear end)" correspond to the front and rear of the vehicle in the longitudinal direction. Arrows R and L indicate the right and left sides as seen from the perspective of an occupant looking forward of the vehicle. Arrow U indicates the upward direction in the vertical direction of the vehicle.

[0015] The front structure of the electric vehicle in this embodiment includes front side members 10 arranged on both sides in the vehicle width direction at the front of the vehicle and extending in the vehicle longitudinal direction, and a motor frame 45 arranged on the lower side of the front side members 10 and supporting a drive unit 1 including an electric motor. In this front structure, a part of the front side member 10 is arranged to overlap the drive mount 1 when viewed from the side, and the inner part in the vehicle width direction of the front side member 10 located outside the drive unit 1 has a weak portion 25 which has lower rigidity than the outer part in the vehicle width direction, and the weak portion 25 is configured to bend so as to protrude outward in the vehicle width direction when a load is applied to the front of the front side member 10.

[0016] As shown in Figure 1, the front structure of the electric vehicle in this embodiment is located on the front side of the dash panel 51. The dash panel 51 is a metal panel that separates the vehicle compartment (passenger compartment) from the power compartment. It extends in the vehicle width direction, connecting both sides of the vehicle body in the vehicle width direction, and extends upward from the front of the floor panel 53, which constitutes the floor of the vehicle compartment. The front structure in this embodiment is located in the power compartment and includes a front side member 10, a motor frame 45, a brace 19, a subframe 35, and a strut tower 31. Each component will be described below.

[0017] The front side members 10 are arranged on both sides in the vehicle width direction at the front part of the vehicle, and are arranged inside the vehicle width direction of the front wheels (not shown). The front side members 10 are highly rigid members formed of a metal material and constitute a part of the vehicle body frame.

[0018] The front side members 10 located on the vehicle front side of the dash panel 51 extend in the vehicle front-rear direction, and the front side members 10 located on the lower side of the dash panel 51 extend outward in the vehicle width direction as they go rearward of the vehicle and are joined to the side sill 55. The side sill 55 is, like the front side members 10, a highly rigid member formed of a metal material and constitutes a part of the vehicle body frame. The side sill 55 in this example extends in the vehicle front-rear direction and is joined to the outside of the vehicle width direction of the floor panel 53.

[0019] Also, a part of the front side members 10 is arranged so as to overlap the drive device 1 in a side view. In the region overlapping the drive device 1, the inner part in the vehicle width direction of the front side members 10 has a vulnerable part 25 with lower rigidity than the outer part in the vehicle width direction.

[0020] The front side members 10 of the present embodiment have a front inner member 11 (inner wall part, front member), a rear inner member 12 (rear member), an outer member 13 (outer wall part), an inner curved member 14, and an outer curved member 15. The vulnerable part 25 and the inner rigidity change part 21 are provided on the front inner member 11. The outer rigidity change part 22, which will be described later, is provided on the outer member 13. The inner rigidity change part 21, the outer rigidity change part 22, and the vulnerable part 25 will be described in detail later.

[0021] First, the front inner member 11 will be described. As shown in Figures 2 and 6, the front inner member 11 has an inner wall portion 11a, an upper surface portion 11c, a lower surface portion 11d, an upper flange portion 11e, and a lower flange portion 11f. The front inner member 11 has a hat-shaped cross-section that opens outward in the vehicle width direction. The inner wall portion 11a has a wall surface facing inward in the vehicle width direction, has a predetermined length in the vehicle vertical direction, and extends in the vehicle longitudinal direction. Also, as shown in Figure 2, an inner recess 11b that is recessed outward in the vehicle width direction is provided in the middle of the inner wall portion 11a in the vehicle vertical direction. The inner recess 11b extends in the vehicle longitudinal direction. The upper and lower ends of the inner recess 11b have ridges, ensuring a predetermined rigidity against loads acting in the vehicle longitudinal direction. In other words, the inner recess 11b functions as a bead that increases the rigidity of the inner wall portion 11a.

[0022] As shown in Figures 1 and 3, the upper portion 11c is the part that extends outward in the vehicle width direction from the upper end of the inner wall portion 11a and extends almost horizontally in the vehicle longitudinal direction. As shown in Figures 6 and 8, the lower portion 11d is the part that extends outward in the vehicle width direction from the lower end of the inner wall portion 11a, and the rear part of the lower portion 11d is slightly inclined downward as it approaches the rear of the vehicle. As shown in Figure 2, the upper flange portion 11e protrudes upward from the outer end in the vehicle width direction of the upper portion 11c and extends in the vehicle longitudinal direction along the outer end of the upper portion 11c. The lower flange portion 11f protrudes downward from the outer end in the vehicle width direction of the lower portion 11d and extends in the vehicle longitudinal direction along the outer end of the lower portion 11d.

[0023] As shown in Figures 2 and 6, the rear inner member 12 is a highly rigid member formed from, for example, high-tensile steel, and is joined to the rear of the front inner member 11. Similar to the front inner member 11, the rear inner member 12 has an inner wall portion 12a, an upper surface portion 12c, a lower surface portion 12d, an upper flange portion 12e, and a lower flange portion 12f, and has a hat-shaped cross-section that opens outward in the vehicle width direction. The inner wall portion 12a of the rear inner member 12 has a wall surface facing inward in the vehicle width direction, has a predetermined length in the vehicle vertical direction, and extends in the vehicle longitudinal direction. In addition, an inner recess 12b that is recessed outward in the vehicle width direction is provided in the middle of the inner wall portion 12a in the vehicle vertical direction. The inner recess 12b extends in the vehicle longitudinal direction. The upper and lower ends of the inner recess 12b have ridges, ensuring a predetermined rigidity against loads acting in the vehicle longitudinal direction. In other words, the inner recess 12b functions as a bead that increases the rigidity of the inner wall portion 12a. The front part of the inner wall portion 12a of the rear inner member 12 is joined to the rear part of the inner wall portion 11a of the front inner member 11.

[0024] The upper surface portion 12c of the rear inner member 12 is the portion that extends outward in the vehicle width direction from the upper end of the inner wall portion 12a, as shown in Figures 1 and 4. The upper surface portion 12c also curves downward as it approaches the rear of the vehicle. The lower surface portion 12d of the rear inner member 12 is the portion that extends outward in the vehicle width direction from the lower end of the inner wall portion 12a, and also curves downward as it approaches the rear of the vehicle.

[0025] As shown in Figure 2, the upper flange portion 12e protrudes upward from the outer end in the vehicle width direction of the upper surface portion 12c and extends in the vehicle longitudinal direction along the outer end of the upper surface portion 12c. The lower flange portion 12f protrudes downward from the outer end in the vehicle width direction of the lower surface portion 11d and extends in the vehicle longitudinal direction along the outer end of the lower surface portion 11d. The upper surface portion 12c, lower surface portion 12d, upper flange portion 12e, and lower flange portion 12f of the rear inner member 12 are joined to the upper surface portion 11c, lower surface portion 11d, upper flange portion 11e, and lower flange portion 11f of the front inner member 11, respectively.

[0026] As shown in Figures 4 and 5, the outer member 13 is a member joined to the outer portion in the vehicle width direction of the front inner member 11 and the outer portion in the vehicle width direction of the rear inner member 12, and has a predetermined length in the vertical direction of the vehicle and extends in the longitudinal direction of the vehicle. The upper part of the outer member 13 is joined to the upper flange portion 11e of the front inner member 11 and the upper flange portion 12e of the rear inner member 12 by spot welding, and the lower part of the outer member 13 is joined to the lower flange portion 11f of the front inner member 11 and the lower flange portion 12f of the rear inner member 12 by spot welding.

[0027] Furthermore, as shown in Figure 2, the outer member 13 has an outer recess 13b in the middle portion in the vehicle's vertical direction, similar to the inner wall portion 12a of the front inner member 11 and the rear inner member 12, which is recessed inward in the vehicle's width direction. The outer recess 13b extends in the vehicle's longitudinal direction, similar to the inner recess 11b. The upper and lower ends of the outer recess 13b have ridges, ensuring a predetermined rigidity against loads acting in the vehicle's longitudinal direction. In other words, the outer recess 13b functions as a bead that increases the rigidity of the outer member 13. The front side member 10, with the inner member and the outer member 13, forms a substantially rectangular closed cross-sectional structure, ensuring a predetermined rigidity.

[0028] As shown in Figures 6 and 7, the inner curved member 14 is joined to the rear of the rear inner member 12. The inner curved member 14 has an inner wall portion 14a, a lower surface portion 14d, an outer flange portion 14g, and an inner flange portion 14h. The inner wall portion 14a of the inner curved member 14 has a wall surface facing inward in the vehicle width direction and curves outward in the vehicle width direction as it approaches the rear of the vehicle. The front part of the inner curved member 14 is joined to the inner wall portion 12a of the rear inner member 12. The length of the inner wall portion 14a in the vehicle vertical direction is formed to gradually decrease as it approaches the rear of the vehicle. In addition, the outer part in the vehicle width direction of the lower cross member 40, which will be described later, is joined to the inner wall portion 14a by spot welding. The lower surface portion 14d of the inner curved member 14 is the part that extends outward in the vehicle width direction from the lower end of the inner wall portion 14a, and curves outward in the vehicle width direction as it approaches the rear of the vehicle, and further curves downward. The outer portion in the vehicle width direction at the rear of the lower surface portion 14d is joined to the side sill 55.

[0029] The outer flange portion 14g protrudes upward from the outer end in the vehicle width direction of the lower surface portion 14d and curves along the outer end in the vehicle width direction of the lower surface portion 14d. The inner flange portion 14h protrudes inward in the vehicle width direction from the upper end of the inner wall portion 14a and curves along the upper end of the inner wall portion 14a. The middle portion in the vehicle width direction of the lower cross member 40 is joined to the inner flange portion 14h.

[0030] The outer curved member 15 is a member joined to the rear of the outer member 13, has a predetermined length in the vertical direction of the vehicle, and curves outward in the width direction of the vehicle as it approaches the rear of the vehicle. The lower part of the outer curved member 15 is joined to the outer flange portion 14g of the inner curved member 14 by spot welding. Furthermore, the rear of the outer curved member 15 may be joined to the side sill 55.

[0031] As shown in Figures 1 and 5, the motor frame 45 is a frame for supporting the drive unit 1, which includes an electric motor for driving, and is a highly rigid member made of metal. The motor frame 45 has a frame main body portion 45a that extends in the vehicle width direction, and side frame portions 45b that extend forward from both sides of the frame main body portion 45a in the vehicle width direction. The side frame portions 45b are located below the front side member 10. The front part of the side frame portion 45b is joined to the front part of the front side member 10 via a brace 19. In addition, a vehicle body connecting portion 45c is provided in the middle part of the side frame portion 45b in the vehicle longitudinal direction. The vehicle body connecting portion 45c extends upward from the upper part of the side frame portion 45b, and the upper part of the vehicle body connecting portion 45c is connected to the lower part of the front side member 10 via a mounting bracket 48, which will be described later.

[0032] As shown in Figure 1, the brace 19 is a metal member that extends in the vertical direction of the vehicle and, like the front side member 10, constitutes part of the vehicle frame. The brace 19 has a front portion 19a and an inner side portion 19b. The upper part of the front portion 19a is joined to the front end of the front side member 10, and the lower part of the front portion 19a is joined to the side frame portion 45b of the motor frame 45.

[0033] Here, the weak point 25 will be described. The weak point 25 is provided on the front side member 10 located on the outer side in the vehicle width direction of the drive unit 1, and is configured to bend so as to protrude outward in the vehicle width direction when an impact load such as a front collision acts on the front of the front side member 10. In this example, as shown in Figures 2 and 3, the weak point 25 is provided on the inner side in the vehicle width direction of the middle part of the front side member 10 in the vehicle longitudinal direction, and is formed to be weaker than the rear of the front side member 10. Furthermore, the weak point 25 is provided on the front side member 10 located on the rear side of the inner rigidity change section 21, and has lower rigidity than the inner rigidity change section 21.

[0034] As shown in Figure 2, the weak point 25 is located approximately at the rear of the inner wall portion 11a of the front inner member 11, in the middle of the vehicle's longitudinal direction. In this example, the weak point 25 is positioned a first distance behind the inner stiffness change portion 21 (stiffness change portion), and a second distance from the rear end of the front inner member 11. The longitudinal length of the first distance is set to be longer than the longitudinal length of the second distance.

[0035] In this embodiment, the outer member 13 is provided with an outer recess 13b. The outer recess 13b extends continuously from the front end to the rear end of the outer member 13. In contrast, the rear part of the inner wall portion 11a of the front inner member 11 is provided with a weak portion 25, so the inner wall portion 11b has lower rigidity than the outer member 13.

[0036] In this way, by providing the weak point 25, when an impact load such as a frontal collision is applied to the front end of the front side member 10, the load is transmitted to the weak point 25, and the weak point 25 can deform by bending so as to be convex outward in the vehicle width direction. In other words, by providing the weak point 25, when an impact load is applied to the front structure of an electric vehicle, the front structure can be deformed in the intended deformation mode, and the impact energy can be effectively absorbed.

[0037] Furthermore, in the region where the front side member 10 and the drive unit 1 overlap in a side view, the vulnerable portion 25 deforms so that it protrudes outward in the vehicle width direction. As a result, the front side member 10 deforms so that it moves away from (spreads outward from) devices such as the drive unit 1 and harnesses on which high voltage is applied, which are located on the front side of the dash panel 51. Therefore, it is possible to suppress the front side member 10 from pressing against and damaging the drive unit 1, etc.

[0038] The vulnerable portion 25 in this embodiment is a recessed groove that is recessed outward in the vehicle width direction and extends in the vehicle vertical direction, and extends continuously from the upper end to the lower end of the inner wall portion of the front inner member 11. As shown in Figure 2, the width of the recessed groove of the vulnerable portion 25 located above the inner recess 11b is substantially constant in the vehicle longitudinal direction from the upper end of the inner wall portion 11a to the upper end of the inner recess 11b. The width of the vulnerable portion 25 provided in the inner recess 11b decreases as it goes downward from the upper end of the inner recess 11b. The width of the recessed groove of the vulnerable portion 25 located below the inner recess 11b is substantially constant from the lower end of the inner recess 11b to the lower end of the inner wall portion 11a.

[0039] In this embodiment, the vulnerable portion 25 is made into a groove extending in the vertical direction of the vehicle, thereby forming a vertically extending ridge on the vulnerable portion 25. When an impact load is received from the front of the vehicle, this ridge becomes the starting point for outward bending, and in the intended deformation mode of the vulnerable portion 25, that is, when an impact load such as a frontal collision is input to the front end of the front side member 10, the vulnerable portion 25 can deform by bending so as to become convex outward in the vehicle width direction.

[0040] Furthermore, as shown in Figure 2, the front side member 10 of this embodiment has a front inner member 11 (front member) that extends in the longitudinal direction of the vehicle, and a rear inner member 12 (rear member) that is joined to the rear of the front inner member 11 and extends from the rear to the rear of the vehicle, with the weak point 25 provided at the rear of the front inner member 11. The rear inner member 12 is made of high-tensile steel and has higher rigidity than the front inner member 11. In other words, the rigidity of the front inner member 11 is set lower than the rigidity of the rear inner member 12.

[0041] In addition, the structure is designed to improve the rigidity of the rear of the front side member 10 compared to the front by forming the rear with a highly rigid material, but this is not the only option. For example, rigidity may be increased by increasing the cross-sectional shape of the rear. Alternatively, rigidity may be increased by providing a reinforcing structure such as a rib structure at the rear.

[0042] As described above, by having a front inner member 11 (front member) and a rear inner member 12 (rear member) with different rigidity levels, when an impact load is applied, the front inner member 11 deforms more easily than the rear inner member 12, which has higher rigidity, making it easier to induce deformation of the weak point 25 provided in the front inner member 11. As a result, the weak point 25 can be generated more reliably when a load is applied, and the intended deformation mode can be obtained.

[0043] Furthermore, in this embodiment, a mounting bracket 48 (mounting portion) is provided at the lower part of the front inner member 11 (front member) for attaching the motor frame 45, and at least a part of the mounting bracket 48 is positioned below the weak portion 25, and the rigidity of the mounting bracket 48 is set lower than the rigidity of the motor frame 45.

[0044] Here, the mounting bracket 48 will be described. As shown in Figure 4, the mounting bracket 48 is a box-shaped structure with an opening at the top and is made of metal. As shown in Figures 4 and 6, the mounting bracket 48 has a front portion 48a, a rear portion 48b, an outer portion 48c, an inner portion 48d, and a bottom portion 48e. As shown in Figure 2, the front portion 48a has a wall surface facing the front of the vehicle and extends from the lower surface portion 11d of the front inner member 11 of the front side member 10, sloping toward the rear of the vehicle as it moves downward toward the vehicle. The upper end of the front portion 48a is provided with a flange that protrudes forward, and the flange is joined to the lower surface portion 11d of the front inner member 11 by spot welding.

[0045] As shown in Figure 2, the rear section 48b has a wall surface facing the rear of the vehicle, is positioned at a distance from the rear of the front section 48a, and extends inclined forward from the lower surface 11d of the front inner member 11 of the front side member 10 as it goes downward towards the vehicle. The upper end of the rear section 48b is provided with a flange that protrudes to the rear, and the flange is joined to the lower surface 11d of the front inner member 11 by spot welding. The rear section 48b and the front section 48a are inclined to move closer to each other as they go downward.

[0046] As shown in Figures 2 and 4, the inner portion 48d connects the inner end of the front portion 48a in the vehicle width direction to the inner end of the rear portion 48b in the vehicle width direction, and the upper end of the inner portion 48d is joined to the lower part of the inner wall portion 11a of the front inner member 11 by spot welding. In this embodiment, the inner portion 48d of the mounting bracket 48 is positioned to cover the lower part of the groove-shaped weak portion 25 from the inside in the vehicle width direction and is spot welded to the front and rear inner wall portions 11a of the weak portion 25. In addition, a through hole 48g is formed in the inner portion 48d. The through hole 48g is an elongated hole extending in the vehicle's longitudinal direction.

[0047] As shown in Figure 4, the outer portion 48c connects the outer end of the front portion 48a in the vehicle width direction to the outer end of the rear portion 48b in the vehicle width direction, and the upper end of the outer portion 48c is joined to the lower flange portion 11f of the front inner member 11 by spot welding. As shown in Figures 2 and 6, the bottom portion 48e is the part that connects to the lower ends of the front portion 48a, the rear portion 48b, the inner portion 48d, and the outer portion 48c, and has a frame mounting hole 48f that penetrates in the vertical direction. The shaft member 45d is passed through the frame mounting hole 48f, and the vehicle body connecting portion 45c of the motor frame 45 is connected to the mounting bracket 48 via the shaft member 45d.

[0048] Since the front end of the motor frame 45 (the front end of the side frame portion 45b) is located further forward than the first weak points 21 and 22, when an impact load such as a frontal collision is applied, an impact load directed towards the rear of the vehicle is input to the side frame portion 45b of the motor frame 45. In this embodiment, when a load is transmitted to the weak point 25, the connection between the mounting bracket 48 and the motor frame 45 is released in conjunction with the deformation mode in which the weak point 25 spreads outward.

[0049] The mounting bracket 48 is less rigid than the motor frame 45. In this example, the mounting bracket 48 is made of sheet metal and is less rigid than the shaft member 45d of the motor frame 45. Therefore, when the mounting bracket 48 moves outward in the vehicle width direction together with the weak part 25, the more rigid shaft member 45d breaks the inner part 48d and bottom part 48e of the mounting bracket 48, releasing the connection between the mounting bracket 48 and the vehicle body connection part 45c of the motor frame 45. As mentioned above, a through hole 48g is formed in the inner part 48d of the mounting bracket 48, reducing the strength of the inner part 48c. Therefore, when the mounting bracket 48 tries to move outward, the shaft member 45d is likely to break the inner part 48c.

[0050] For example, an impact load caused by a frontal collision is input to the front end of the side frame portion 45b of the motor frame 45, and then, with a slight delay, to the front end of the front side member 10. At this time, the impact load is transmitted from the front to the rear of the side frame portion 45b of the motor frame 45, causing the motor frame 45 to move backward. As a result, a load directed towards the rear of the vehicle acts on the mounting bracket 48. Furthermore, when the vulnerable portion 25 deforms outward in response to the impact load, a load (a load in the vehicle width direction) acts on the mounting bracket 48 to resist the deformation of the vulnerable portion 25.

[0051] As described above, when a load along the vehicle's longitudinal and vehicle width directions acts on the mounting bracket 48, the mounting bracket 48 breaks, and the connection between the front side member 10 and the motor frame 45 at the mounting bracket 48 is released. This release of connection promotes the deformation of the weak point 25, allowing the desired deformation mode to be obtained. In this embodiment, the mounting bracket 48 is positioned below the weak point 25, but this is not limited to this configuration. For example, a part of the mounting bracket 48 may be positioned below the weak point 28 and towards the front of the vehicle. In this case as well, a load mainly along the vehicle's longitudinal direction acts on the mounting bracket 48, causing it to break and allowing the same deformation mode as described above to be obtained.

[0052] Furthermore, the front side member 10 of this embodiment includes an inner wall portion 11a of a front inner member 11 that is provided with a weak portion 25 and faces the inside of the vehicle, and an outer member 13 (outer wall portion) that is spaced apart on the outside in the vehicle width direction of the inner wall portion 11a. A reinforcement 28 is arranged to connect the inner wall portion 11a and the outer member 13, and the reinforcement 28 is joined to the front and rear sides of the weak portion 25.

[0053] The reinforcement 28 will now be described. As shown in Figure 4, the reinforcement 28 has an outer surface portion 28c that is positioned opposite the inner surface of the outer member 13, a front surface portion 28a that extends inward in the vehicle width direction from the front end of the outer surface portion 28c, and a rear surface portion 28b that extends inward in the vehicle width direction from the rear end of the outer surface portion 28c. The outer surface portion 28c has a recess formed therein that corresponds to the outer recess 13b. The outer surface portion 28c is positioned with a gap inward in the vehicle width direction relative to the outer member 13.

[0054] A front upper flange 28a1 is provided at the upper end of the front portion 28a, projecting forward of the vehicle, and the front upper flange 28a1 is joined to the upper surface portion 11c of the front inner member 11 by spot welding. Furthermore, a front inner flange 28a2 is provided at the inner end of the front portion 28a in the vehicle width direction, projecting forward, and the front inner flange 28a2 is joined to the inner wall portion 11a of the front inner member 11 by spot welding. In addition, a front lower flange 28a3 is provided at the lower end of the front portion 28a, projecting forward of the vehicle, and the front lower flange 28a3 is joined to the lower surface portion 11d of the front inner member 11 by spot welding. In this example, the front lower flange 28a3, the lower surface portion 11d, and the flange 48a1 of the front portion 48a of the mounting bracket 48 are joined by spot welding in a three-layer stacked state.

[0055] As shown in Figures 4 and 8, the upper rear flange 28b1 is provided at the upper end of the rear portion 28b, projecting forward of the vehicle, and the upper rear flange 28b1 is joined to the upper surface portion 11c of the front inner member 11 by spot welding. Furthermore, the inner rear flange 28b2 is provided at the inner end of the rear portion 28b in the vehicle width direction, projecting backward of the vehicle, and the inner rear flange 28b2 is joined to the inner wall portion 11a of the front inner member 11 by spot welding. In addition, the lower rear flange 28b3 is provided at the lower end of the rear portion 28b, projecting backward of the vehicle, and the lower rear flange 28b3 is joined to the lower surface portion 11d of the front inner member 11 by spot welding. The lower rear flange 28b3, the lower surface portion 11d, and the flange 48b1 of the rear portion 48b of the mounting bracket 48 are joined by spot welding in a three-layer stacked state.

[0056] The front inner flange 28b2 is joined to the inner wall portion 11a located on the front side of the weak portion 25, and the rear inner flange 28b2 is joined to the inner wall portion 11a located on the rear side of the weak portion 25. By joining the reinforcements 28 to the front and rear of the weak portion 25, the rigidity around the weak portion 25 is improved, and the deformation of the weak portion 25 is promoted. In addition, stress is concentrated in the weak portion 25, which further promotes the deformation of the weak portion 25.

[0057] Furthermore, the lower part of the reinforcement 28 is joined to the mounting bracket 48. In this example, the front lower flange 28a3 and the rear lower flange 28b3 are joined to the mounting bracket 48 via the lower surface portion 11d. As a result, the area around the mounting bracket 48 is more rigid than the mounting bracket 48 itself. Consequently, when an impact load is applied, the rearward movement of the motor frame 45 and the outward bending deformation of the front side member 10 effectively break the mounting bracket 48, releasing the connection between the motor frame 45 and the front side member 10.

[0058] In this embodiment, the reinforcement 28 is integrally formed from an outer surface portion 28c, a front surface portion 28a, and a rear surface portion 28b, but is not limited to this. The reinforcement 28 may be composed of two members, as long as the front surface portion 28a and the rear surface portion 28b are arranged adjacent to each other in front of and behind the weak part 25. For example, the front reinforcement corresponding to the front surface portion 28a may be placed on the front side of the weak part 25, and the rear reinforcement corresponding to the rear surface portion 28b may be placed on the rear side of the weak part 25. In this case, the front reinforcement may be placed above the front side portion 48a of the mounting bracket 48, and the rear reinforcement may be placed above the rear side portion 48b. This promotes deformation of the weak part 25, similar to the above.

[0059] Furthermore, the front structure of this embodiment has a subframe 35 positioned on the upper side of the vehicle above the front side member 10, extending along the vehicle width direction to connect both sides of the vehicle body, with a gap between the front side member 10 and the subframe 35. In this example, the subframe 35 is joined to strut towers 31 positioned on both sides in the vehicle width direction at the front of the vehicle. The strut towers 31 and the subframe 35 will be described below.

[0060] As shown in Figures 1 and 6, the strut tower 31 is joined to each of the front side members 10 on both sides in the vehicle width direction and extends in the vehicle vertical direction. As shown in Figure 1, the strut tower 31 is located on the front side of the vehicle on the outer side in the vehicle width direction of the dash panel 51. The strut tower 31 is made of a metal material and has an inner portion 31a, a front portion 31b, and a top portion 31c. The inner portion 31a has a wall surface facing inward in the vehicle width direction. A flange is provided at the rear of the inner portion 31a, and this flange is joined to the dash panel 51 by spot welding.

[0061] The front section 31b has a wall surface that extends outward in the vehicle width direction from the front of the inner section 31a. A subframe 35 is joined to the front section 31b. The inner section 31a and the front section 31b are integrally formed. The top section 31c is a separate component from the inner section 31a and the front section 31b, and is joined to the upper part of the inner section 31a and the upper part of the front section 31b.

[0062] The coil springs and shock absorbers that constitute the suspension are arranged inside the strut tower 31, that is, in the space on the outer side of the inner portion 31a in the vehicle width direction. The upper part of the shock absorber is attached to the top surface portion 31c. The strut tower 31 has high rigidity, especially in the vertical direction of the vehicle, and can effectively receive the load transmitted from the shock absorbers and the like.

[0063] As shown in Figure 1, the subframe 35 is a member that extends in the vehicle width direction so as to connect the strut towers 31 on both sides at the front of the vehicle, and is made of a metal material. In this example, the subframe 35 has a central member 36 located in the middle of the vehicle width direction and an outer extension member 37 positioned on the outside of the central member 36 in the vehicle width direction.

[0064] The central member 36 is the portion that extends in the vehicle width direction and is positioned at a distance from the front of the dash panel 51. The outer extension member 37 is joined to the outer end of the central member 36 in the vehicle width direction. The outer extension member 37 extends outward in the vehicle width direction from the outer end of the central member 36 to a position corresponding to the outer part of the front side member 10, and from that position it extends upward in inclination as it moves outward in the vehicle width direction. A flange is provided at the rear of the outer extension member 37, and this flange is joined to the front part 31b of the strut tower 31 by spot welding. The outer end of the outer extension member 37 is also joined to the apron side member 52. The lower part of the outer extension member 37 is positioned at a distance from the upper surface 11c of the front inner member 11 and the upper surface 12c of the rear inner member 12 of the front side member 10, as shown in Figures 2 and 6. The outer extension member 37 is also positioned above the weak point 25, as shown in Figure 2.

[0065] For example, electrical components are fixed to the subframe 35. Since the subframe 35 is joined to the apron side member 52 and the strut tower 31, the electrical components can be fixed stably. Because the subframe 35 and the front side member 10 are spaced apart, the deformation of the weak part 25 of the front side member 10 is less likely to be hindered, and the front side member 10 can be deformed in the intended deformation mode.

[0066] Furthermore, in this embodiment, an inner rigidity change section 21 (rigidity change section) is provided on the inner side of the front side member 10 in the vehicle width direction, on the vehicle front side of the weak section 25, in which a plurality of low-rigidity sections 21a and a plurality of high-rigidity sections 21b having higher rigidity than the low-rigidity sections 21a are alternately arranged in the vehicle longitudinal direction, and the front part of the inner rigidity change section 24 is located on the vehicle front side of the drive unit 1 in the vehicle longitudinal direction.

[0067] The internal stiffness change section 21 is provided at the front of the inner wall portion in the vehicle width direction of the front side member 10. In this example, as shown in Figures 1 and 2, the internal stiffness change section 21 is provided at the front of the inner wall portion 11a of the front inner member 11 of the front side member 10. Furthermore, the internal stiffness change section 21 is composed of a plurality of low-stiffness sections 21a and a plurality of high-stiffness sections 21b arranged alternately in the vehicle longitudinal direction.

[0068] In this example, the low-rigidity portion 21a of the inner rigidity change portion 21 is a recessed groove that is recessed outward in the vehicle width direction and extends in the vehicle vertical direction. As shown in Figure 2, two low-rigidity portions 21a are provided on the inner wall portion 11a located above the inner recess 11b and are spaced apart from each other in the front-rear direction. Furthermore, two low-rigidity portions 21a are provided on the inner wall portion 11a located below the inner recess 11b and are spaced apart from each other in the front-rear direction. The low-rigidity portions 21a above and below the inner recess 11b are arranged side by side in the vehicle vertical direction. The low-rigidity portions 21a located at the front and aligned vertically are spaced further rearward than the front end of the inner wall portion 11a of the front inner member 11.

[0069] The high-rigidity portion 21b of the inner rigidity change portion 21 is located adjacent to the low-rigidity portion 21a in the longitudinal direction of the vehicle, and is provided on the inner wall portion 11a located in front of and behind the low-rigidity portion 21a. That is, similar to the low-rigidity portion 21a, the high-rigidity portion 21b is provided on both the inner wall portion 11a located above the inner recess 11b and the inner wall portion 11a located below the inner recess 11b.

[0070] Ridges extending in the vertical direction of the vehicle are formed at the front and rear ends of the low-rigidity section 21a. For example, when an impact load such as a frontal collision is applied to the front end of the front side member 10, the ridges become the starting points for deformation, and the inner rigidity change section 21 can deform so as to collapse in the longitudinal direction of the vehicle.

[0071] The outer rigidity change section 22 is provided at the front of the outer wall portion in the vehicle width direction of the front side member 10. In this example, as shown in Figures 3 and 4, the outer rigidity change section 22 is provided at the front of the outer member 13 of the front side member 10. Furthermore, similar to the inner rigidity change section 21, the outer rigidity change section 22 is composed of a plurality of low-rigidity sections 22a and a plurality of high-rigidity sections 22b arranged alternately in the vehicle longitudinal direction.

[0072] The low-rigidity portion 22a of the outer rigidity change portion 22 is a groove that is recessed inward in the vehicle width direction and extends in the vehicle vertical direction. As shown in Figures 4 and 5, two low-rigidity portions 22a are provided on the outer member 13 located above the outer recess 13b, and two more low-rigidity portions 22a are provided on the outer member 13 located below the outer recess 13b. The low-rigidity portions 22a above the outer recess 13b and the low-rigidity portions 22a below the outer recess 13b are arranged side by side in the vehicle vertical direction. The vertically aligned low-rigidity portions 22a located at the front are spaced further rearward than the front end of the inner wall portion 11a of the front inner member 11.

[0073] As shown in Figure 4, the high-rigidity portion 22b of the outer rigidity change portion 22 is located adjacent to the low-rigidity portion 22a in the vehicle longitudinal direction, similar to the high-rigidity portion 21b of the inner rigidity change portion 21, and is provided with outer members 13 located in front of and behind the low-rigidity portion 22a. That is, the high-rigidity portion 22b is provided on both the upper and lower sides of the outer recess 13b, similar to the low-rigidity portion 22a.

[0074] Furthermore, as shown in Figure 3, the low-rigidity portion 22a and the high-rigidity portion 22b of the outer rigidity change portion 22 are arranged to correspond to the low-rigidity portion 21a and the high-rigidity portion 21b of the inner rigidity change portion 21. For example, the low-rigidity portion 22a of the outer rigidity change portion 22 is positioned outside the low-rigidity portion 21a of the inner rigidity change portion 21 in the vehicle width direction, and is positioned so that their positions are aligned in the vehicle vertical direction. Similarly, the high-rigidity portion 22b of the outer rigidity change portion 22 is positioned outside the high-rigidity portion 21b of the inner rigidity change portion 21 in the vehicle width direction, and is positioned so that their positions are aligned in the vehicle vertical direction.

[0075] Furthermore, at least a portion of the stiffness change sections 21 and 22 are located further rearward than the front end of the motor frame 45, as shown in Figure 5. In this example, the front ends of the inner stiffness change section 21 and the outer stiffness change section 22 are located further forward than the front end of the side frame section 45b of the motor frame 45.

[0076] Since the front side member 10 is provided with both rigidity change sections 21, 22 and a weak section 25, when an impact load is applied to the front of the front side member 10, the load can be transmitted to both the rigidity change sections 21, 22 and the weak section 25. In other words, when an impact load is applied, the front side member 10 can be deformed in the intended deformation mode, and the impact energy caused by the impact load can be effectively absorbed.

[0077] When an impact load, such as from a frontal collision, is applied to the front of the vehicle, the low-rigidity section 21a located between the two high-rigidity sections 21b of the inner rigidity change section 21 deforms so as to collapse in the longitudinal direction of the vehicle. Similarly, the low-rigidity section 22a located between the two high-rigidity sections 22b of the outer rigidity change section 22 collapses in the longitudinal direction of the vehicle. Multiple low-rigidity sections 21a and 22a of the rigidity change sections 21 and 22 collapse sequentially from the front to the rear.

[0078] For example, by providing an internal rigidity change section 21, the inner part of the front of the front side member 10 can be crushed. This makes it possible to give the front of the front side member 10 a trigger for deformation that causes the front side member 10 to bend outwards.

[0079] For example, when an object (collision object) having a predetermined length in the vertical direction of the vehicle collides with the front of the vehicle, the impact load generated by the collision acts on the front of the vehicle. If the lower part of the front of the vehicle is located further forward than the upper part of the front of the vehicle, the collision object will collide with the front of the motor frame 45 before the front side member 10, and then with the front of the front side member 10. In other words, the timing of the collision object's impact with the front side member 10 will be slightly delayed compared to the timing of its impact with the motor frame 45.

[0080] Here, when an impact load acts on the front of the vehicle along the longitudinal direction of the front side member 10 (in this example, the horizontal direction perpendicular to the vehicle width direction), a slight difference in the timing of the collision causes a tilt in the longitudinal direction of the front side member 10 in the direction in which the impact load acts. In this way, when a load acts in a direction that tilts with respect to the longitudinal direction (axial direction) of the front side member 10, it is possible to trigger a bending deformation in the stiffness change parts 21 and 22.

[0081] When an impact load is applied to the stiffness change sections 21 and 22, the low-stiffness section 21a of the inner stiffness change section 21 and the low-stiffness section 22a of the outer stiffness change section 22 deform in a way that causes them to collapse. In other words, the inner stiffness change section 21 and the outer stiffness change section 22 deform in a way that causes them to collapse in the longitudinal direction (axial direction) of the front side member 10. By deforming the inner stiffness change section 21 and the outer stiffness change section 22, a portion of the impact energy generated by the impact load is absorbed.

[0082] Subsequently, a portion of the impact load is transmitted to the weak point 25, which is located behind the stiffness-changing sections 21 and 22. At this time, the weak point 25 deforms by bending so as to be convex outward in the vehicle width direction. Therefore, the amount of deformation of the weak point 25 (the amount by which the weak point 25 deforms outward) can be set to be greater than the amount of deformation of the stiffness-changing sections 21 and 22 (the amount of axial crushing, the amount of collapse in the longitudinal direction). In other words, the weak point 25 can absorb more impact energy than the amount of impact energy absorbed by the stiffness-changing sections 21 and 22.

[0083] Furthermore, as the intermediate portion of the front side member 10 in the vehicle's longitudinal direction deforms to bend outward, the weak portion 25 deforms to be pushed outward in the vehicle's width direction. Due to this deformation, the impact load can be absorbed not only by the deformation of the stiffness-changing portions 21, 22 and the weak portion 25, but also by the entire front side member 10.

[0084] Furthermore, since the deformation amount of the vulnerable part 25 can be set to be large, the impact energy transmitted to the rear side of the dash panel 51 can be effectively reduced. In other words, according to this embodiment, when an impact load is applied to the front of the vehicle, it is possible to reduce the amount by which the dash panel 51 moves backward.

[0085] The description of this embodiment is illustrative for explaining the present invention and does not limit the invention as described in the claims. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0086] For example, in this embodiment, a groove is provided to cause the weak portion 25 to bend outward, but this is not limited to this. The weak portion 25 only needs to have lower rigidity than its surroundings, and for example, the weak portion 25 may have a bent shape with a ridge extending in the vertical direction of the vehicle. [Explanation of Symbols]

[0087] 1. Drive unit 10 Front side member (side member) 11 Front inner member (front member) 11a Inner wall 11b Inner recess 11c Top part 11d Bottom part 11e Upper flange section 11f Lower flange section 12. Rear inner member (rear member) 12a Inner wall 12b Inner recess 12c Top part 12d Bottom part 12e Upper flange section 12f Lower flange section 13 Outer Member 13b Outer recess 14 Inner curved member 14a Inner wall 14d Bottom part 14g outer flange section 14h Inner flange section 15 Outer curved member 18 Reinforcement Panels 19 Brace 19a Front part 19b Inner side 21. Internal stiffness change section (stiffness change section) 21a Low rigidity part 21b High rigidity part 21c Through hole 21d Through round hole 22. External stiffness change section (stiffness change section) 22a Low rigidity part 22b High rigidity part 25 Vulnerable parts 28 Reinforcement 28a Front part 28a1 Front upper flange 28a2 Front inner flange 28a3 Front lower flange 28b Rear part 28b1 Rear upper flange 28b2 Rear inner flange 28b3 Rear lower flange 28c External part 31 Strut Tower 31a Inside part 31b Front part 31c Top section 35 Subframes 36 Central Member 37 Outer extension member 40 Lower Cross Member 41 Front wall 41a Upper front flange 42 Bottom part 43 Rear wall 43a Upper rear flange 43b Protrusion 45 Motor Frame 45a Frame main body 45b Side frame section 45c Body coupling section 45d shaft member 48 Mounting bracket 48a Front side 48b Rear side 48c outer part 48d Inner part 48e Bottom part 48g through hole 48f Frame mounting holes 51. Dashboard 52 Apron Side Members 53 Floor Panel 55 Side sill

Claims

1. A front structure for an electric vehicle, comprising: side members positioned on both sides in the width direction of the vehicle front and extending in the longitudinal direction of the vehicle; and a motor frame positioned below the side members and supporting a drive unit including an electric motor, A portion of the aforementioned side member is positioned to overlap the drive mount when viewed from the side. The inner portion in the vehicle width direction of the side member located outside the drive unit has a weaker portion that is less rigid than the outer portion in the vehicle width direction. The front structure of an electric vehicle is characterized in that the weak portion is configured to bend so as to protrude outward in the vehicle width direction when a load is applied to the front of the side member.

2. The side member comprises a front member and a rear member joined to the rear of the front member and extending from the rear toward the rear of the vehicle. The rigidity of the front member is set lower than that of the rear member. The front vehicle structure according to claim 1, characterized in that the vulnerable portion is located on the inner side of the front member in the vehicle width direction.

3. A mounting portion is provided at the lower part of the front member for attaching the motor frame. At least a portion of the mounting portion is located below the weak portion. The front structure of an electric vehicle according to claim 2, characterized in that the rigidity of the mounting portion is set lower than the rigidity of the motor frame.

4. The side member includes an inner wall portion on which the vulnerable portion is provided and facing the inside of the vehicle, and an outer wall portion arranged at a distance from the outer side of the inner wall portion in the vehicle width direction, A reinforcement is positioned to connect the inner wall portion and the outer wall portion. The front structure of an electric vehicle according to claim 1, characterized in that the reinforcement is joined to the front and rear sides of the weak portion.

5. The front structure of an electric vehicle according to claim 4, characterized in that the lower part of the reinforcement is joined to the mounting portion.

6. The front structure of an electric vehicle according to claim 1, characterized in that the weak portion is a groove extending in the vertical direction of the vehicle.

7. The aforementioned side member has a subframe positioned on the upper side of the vehicle, extending along the width direction of the vehicle to connect both sides of the vehicle body, The front structure of an electric vehicle according to claim 1, characterized in that the side member and the subframe are arranged with a gap between them.

8. On the inner side of the side member in the vehicle width direction, on the vehicle front side of the weak portion, a rigidity variation section is provided, in which a plurality of low-rigidity portions and a plurality of high-rigidity portions having higher rigidity than the low-rigidity portions are alternately arranged in the vehicle longitudinal direction. The front structure of an electric vehicle according to claim 1, characterized in that, in the longitudinal direction of the vehicle, the front portion of the rigidity change portion is located further forward than the drive unit.

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