Front structure of electric vehicle

Abstract

The front structure of an electric vehicle is designed to deform in the intended mode when subjected to an impact load, thereby effectively absorbing impact energy. [Solution] In the front structure of the electric vehicle, an inner rigidity change section 21 is provided at the front of the inner part of the front side member 10. The inner rigidity change section 21 has a plurality of low-rigidity sections 21a and a plurality of high-rigidity sections 21b arranged alternately in the front-rear direction. The front side member 10 located on the rear side of the inner rigidity change section 21 is provided with a weak section 25 having lower rigidity than the high-rigidity section 21b.

Description

Technical Field

[0001] The present invention relates to the 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 vulnerable 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 disposed on both sides in the vehicle width direction at the front of the vehicle, and a sub-frame disposed below the front side frame. A rigidity change part is provided in the front side frame, and a vulnerable part is provided in the sub-frame. In the structure of this example, when an impact load from the front side of the vehicle is input to the front part of the vehicle body, immediately after the input, for example, members such as a bumper beam and a bumper beam extension are crushed, thereby absorbing a part of the impact energy caused by the impact load. Thereafter, the impact load is transmitted to the front side frame and the sub-frame.

[0004] The rigidity change part provided in the front side frame has a recess provided in the intermediate part in the vehicle front-rear direction of the front side frame, and when receiving an impact load, the recess is deformed so as to bend inward in the vehicle width direction. Further, the vulnerable part provided in the sub-frame is deformed so as to bend downward when receiving an impact load.

[0005] As described above, in the structure of the above example, when an impact load is input to, for example, a bumper beam at the front of the vehicle, the rigidity change part and the vulnerable part are deformed to stably absorb the impact energy caused by the impact load.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2016-150685 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, 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, immediately after an impact load acts on the front of the vehicle body, the bumper beam, etc., will collapse, but depending on the amount and direction of deformation of these members, unintended load transmission may occur to the front side frame and subframe, and as a result, only one of the rigidity change parts and the weak points may deform. In such cases, it may become difficult to absorb the impact as intended.

[0008] Furthermore, for example, if a weak point in the subframe is set to have higher rigidity than a rigidity-changing point, when an impact load from a frontal collision is applied, only the rigidity-changing point may deform. In such a case, the front side frame may collapse too much, and the amount the dash panel retracts when subjected to an impact load may be greater than expected.

[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 an electric motor. In the front structure of the electric vehicle, the front part of the inner part of the side member in the vehicle width direction is provided with a rigidity change section in which a plurality of low-rigidity sections and a plurality of high-rigidity sections having higher rigidity than the low-rigidity sections are alternately arranged in the vehicle longitudinal direction, and the side member located on the rear side of the rigidity change section is provided with a weak section having lower rigidity than the high-rigidity sections. [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., 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]Figure 1 is a top view with the motor frame omitted, and the reinforcing panel on the right side has been omitted. [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 (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 45 arranged on the lower side of the front side members 10 and supporting the electric motor 1. Furthermore, in this front structure, an inner rigidity change section 21 (rigidity change section) is provided at the front of the inner part in the vehicle width direction of the front side member 10, 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 arranged alternately in the vehicle longitudinal direction, and a weak section 25 having lower rigidity than the high-rigidity sections 21b is provided at the inner part in the vehicle width direction of the front side member 10 located on the vehicle rear side of the inner rigidity change section 21.

[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. In other words, the front structure of 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 member 10 is disposed on both sides in the vehicle width direction at the front part of the vehicle and is disposed inside the vehicle width direction of the front wheels (not shown). The front side member 10 is a highly rigid member formed of a metal material and constitutes a part of the vehicle body frame.

[0018] The front side member 10 located on the vehicle front side of the dash panel 51 extends in the vehicle front-rear direction, and the front side member 10 located on the lower side of the dash panel 51 extends outward in the vehicle width direction as it goes toward the rear of the vehicle and is joined to the side sill 55. The side sill 55 is a highly rigid member formed of a metal material like the front side member 10 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] The front side member 10 of the present embodiment has a front inner member 11 (inner wall portion, front member), a rear inner member 12 (rear member), an outer member 13 (outer wall portion), an inner curved member 14, and an outer curved member 15. The inner rigidity change portion 21 and the vulnerable portion 25 are provided on the front inner member 11. The outer rigidity change portion 22 described later is provided on the outer member 13. The inner rigidity change portion 21, the outer rigidity change portion 22, and the vulnerable portion 25 will be described in detail later.

[0020] 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.

[0021] 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 7, 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] As shown in Figures 1 and 5, the motor frame 45 is a frame for supporting the electric motor 1 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.

[0031] 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. In addition, an outer flange portion 13f that protrudes outward in the vehicle width direction is provided at the front end of the outer member 13, and the front portion 19a of the brace 19 is joined to the outer flange portion 13f.

[0032] Here, the stiffness change sections 21 and 22 will be described. As shown in Figures 1 and 2, the stiffness change sections 21 and 22 are provided at the front of the front side member 10 and are formed to be weaker than the rear of the front side member 10. The stiffness change sections 21 and 22 consist of an inner stiffness change section 21 and an outer stiffness change section 22.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Ridges extending in the vehicle's vertical direction 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 point for deformation, and the inner rigidity change section 21 can deform to collapse in the vehicle's longitudinal direction.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] Next, the weak point 25 will be described. The weak point 25 is provided on the front side member 10 located on the rear side of the vehicle of the inner rigidity change section 21, and has lower rigidity than the inner rigidity change section 21. 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 in the middle part of the front side member 10 in the vehicle's longitudinal direction, and is formed to be weaker than the rear part of the front side member 10.

[0043] 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.

[0044] 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 11a 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. When an impact load such as a frontal collision is applied 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] Furthermore, as shown in Figures 1 to 3, in this embodiment, as described above, the stiffness change sections 21 and 22 are provided on the inner and outer parts of the front side member 10 in the vehicle width direction, respectively, and each of the stiffness change sections 21 and 22 provided on the inner and outer parts is configured by alternately arranging low-stiffness sections 21a and 22a and high-stiffness sections 21b and 22b in the vehicle longitudinal direction. In this example, the inner stiffness change section 21 and the outer stiffness change section 22 are arranged with low-stiffness sections 21a and 22a and high-stiffness sections 21b and 22b in a so-called bellows shape.

[0055] In this way, the low-rigidity sections 21a, 22a and high-rigidity sections 21b, 22b of the rigidity-changing sections 21, 22 are arranged in pairs in the vehicle width direction, making the front part of the front side member 10 more prone to collapsing in a bellows-like manner. As a result, the front part of the front side member 10 becomes more prone to collapsing in the longitudinal direction of the front side member 10.

[0056] Furthermore, as described above, the front structure of this embodiment has a brace 19 that covers the front end of the front side member 10, and a side portion 19b (extension portion) extending toward the rear of the vehicle is provided on the inner side of the brace 19 in the vehicle width direction, and the extension portion 19b is joined to the outer flange portion 13f of the front side member 10.

[0057] An impact load is applied to the front end of the front side member 10 via the brace 19, causing the inner rigidity change portion 21 to collapse, which in turn triggers deformation that causes the front side member 10 to bend outward.

[0058] At the front of the front side member 10, an outer flange portion 13f is provided at the front end of the outer member 13, allowing the rigidity of the outer portion in the vehicle width direction to be set higher than that of the inner portion. A portion of the load applied to the front side member 10 is transmitted via the inner surface portion 19b of the brace 19 along the inner wall portion 11a of the front inner member 11 toward the rear of the vehicle, and a portion of the load is transmitted via the front portion 19 of the brace 19, etc. toward the outward portion in the vehicle width direction.

[0059] Even when the load is transmitted to the rearward side of the vehicle beyond the rigidity change sections 21 and 22 of the front side member 10, and deformation causing the weak section 25 to bend outward begins, the trajectory of the colliding object does not change, and the impact load is transmitted toward the rear of the vehicle. Therefore, the inner rigidity change section 21 and the outer rigidity change section 22 collapse to absorb the impact, while the deformation of the weak section 25 to bend outward is promoted, thus maintaining the impact absorption effect.

[0060] Furthermore, in this embodiment, as described above, an outer flange portion 13f is provided on the outer side in the vehicle width direction at the front of the front side member 10, and the front portion 19a of the brace 19 is joined to the outer flange portion 13f. In addition, through holes 21c and 21d are formed in the inner rigidity change portion 21 of the front side member 10. In this example, as shown in Figure 2, among the low rigidity portions 21a of the inner rigidity change portion 21, an elongated through hole 21c extending in the vehicle vertical direction is formed in the low rigidity portion 21a located on the front side, and a round through hole 21d is formed in the inner recess 11b located between the upper and lower low rigidity portions 21a located on the front side.

[0061] By providing these through holes 21c and 21d, the rigidity of the rigidity change sections 21 and 22 is set lower on the inner side of the front side member 10 than on the outer side. In other words, the rigidity of the inner rigidity change section 21 is set lower than the rigidity of the outer rigidity change section 22.

[0062] In the configuration of this embodiment, as described above, during a collision, the vulnerable portion 25 deforms by bending so that it protrudes outward in the vehicle width direction. Here, the outer flange portion 13f and the front portion 19a of the brace 19 are joined to the front side of the outer rigidity change portion 22, and through elongated holes 21c and through round holes 21d are provided in the inner rigidity change portion 21, etc., to reduce rigidity. As a result, when an impact load is input to the front side member 10, the low-rigidity portion 21a located in front of the inner rigidity change portion 21 deforms first by collapsing. Subsequently, the bellows-shaped inner rigidity change portion 21 and outer rigidity change portion 22 deform.

[0063] As deformation begins to collapse from the inner stiffness change section 21, the impact load transmitted from the stiffness change sections 21 and 22 to the weak section 25 is transmitted in a direction that is slightly inclined outward in the vehicle width direction as it moves towards the rear of the vehicle. That is, the inner stiffness change section 21 collapses first, and a load transmission path is created that moves from the inner part at the front of the front side member 10 to the outer part at the rear. For example, a transmission path is formed in the direction of arrow X in Figure 3. As a result, it becomes possible to more reliably generate deformation in which the weak section 25 bends so that it protrudes outward in the vehicle width direction.

[0064] Furthermore, in this embodiment, a protruding flange portion (projection) is provided on the upper part of the side member located above the through holes 21c and 21d. In this example, the protruding flange portion 11e1 is provided on the front part of the upper flange portion 11e of the front inner member 11. This increases the rigidity of the portion where the protruding flange portion 11e1 is provided, thereby promoting deformation of the portion where the through holes 21c and 21d are formed.

[0065] Furthermore, as described above, the brace 19 extends in the vertical direction of the vehicle, the lower part of the brace 19 is joined to the motor frame 45, and the front end of the motor frame 45 is positioned on the vehicle-forward side of the rigidity change sections 21 and 22. In this example, the lower part of the front section 19a of the brace 19 is joined to the front part of the side frame section 45b of the motor frame 45. Also, the front part of the side frame section 45b of the motor frame 45 is positioned on the vehicle-forward side of the rigidity change sections 21 and 22.

[0066] When an impact load acts on the front of the vehicle, as described above, the impact load acts on the front of the side frame portion 45b of the motor frame 45 toward the rear of the vehicle, and then the impact load acts on the front of the front side member 10. In other words, a force acts on the motor frame 45 to move toward the rear of the vehicle before the load acts on the front side member 10. As a result, stress concentrates in the stiffness change portions 21 and 22. Therefore, the impact load is reliably transmitted by the stiffness change portions 21 and 22, and the impact energy can be absorbed in the stiffness change portions 21 and 22. It is also possible to adjust the position of the motor frame 45 so that stress concentration is more likely to occur in the stiffness change portions 21 and 22.

[0067] Furthermore, in this embodiment, the front end of the electric motor 1 is positioned further rearward than the front ends of the stiffness change sections 21 and 22, and the front end of the motor frame 45 is positioned further forward than the front end of the front side member 10. In this example, the stiffness change sections 21 and 22 are positioned further forward than the electric motor 1, as shown in Figure 5. Of the low-rigidity sections 21a and 22a of the stiffness change sections 21 and 22, the front low-rigidity sections 21a and 22a are positioned further forward than the electric motor 1. With this arrangement, a certain amount of impact energy is absorbed by the stiffness change sections 21 and 22, and then the impact load is transmitted to the electric motor 1. That is, since the load is transmitted to the electric motor 1 with reduced impact energy, the protective effect of the electric motor 1 can be enhanced.

[0068] Furthermore, in this embodiment, the front end of the motor frame 45 is positioned further forward than the front end of the front side member 10, so the front end of the motor frame 45 is positioned further forward than the rigidity change sections 21 and 22.

[0069] When an impact load is applied to the front of the vehicle, while the stiffness-changing sections 21 and 22 are compressed, a force acts on the motor frame 45 to move it towards the rear of the vehicle. As a result, the motor frame 45 is pushed towards the rear of the vehicle by the amount that the stiffness-changing sections 21 and 22 are compressed (the amount within which it can be crushed). Consequently, the electric motor 1 and its surrounding components can be protected.

[0070] Furthermore, as the motor frame 45 is pushed towards the rear of the vehicle, load concentration occurs on the front part (rigidity change section 21, 22) of the front side member 10, making it easier to control the deformation mode.

[0071] Furthermore, in this embodiment, the rigidity-changing portions 21 and 22 have a recess and a convex portion arranged side by side in the longitudinal direction of the vehicle, with the recess constituting a low-rigidity portion 21a and the convex portion constituting a high-rigidity portion 21b. Since the recess is a low-rigidity portion 21a, it is possible to deform by crushing the recess. In addition, since the low-rigidity portion 21a, which is a recess, is provided on the inner side of the front part of the front side member 10, the low-rigidity portion 21a can be used as a starting point for the fragile portion 25 to bend outward. This makes it possible to deform the front side member 10 in the intended deformation mode.

[0072] Furthermore, as described above, the weak point 25 is located on the inner side of the front side member 10 in the vehicle width direction, in the middle of the vehicle's longitudinal direction, and is recessed outward in the vehicle width direction and extends in the vehicle's vertical direction. Therefore, the weak point 25 can undergo deformation that causes it to bend outward in the vehicle width direction.

[0073] 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, and the rigidity change portion 21, 22 and the weak portion 25 are provided in the front inner member 11. Also, as described above, the rear inner member 12 is made of high-tensile steel plate and has higher rigidity than the front inner member 11.

[0074] 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.

[0075] In this embodiment, since the front inner member 11 is provided with an inner stiffness change section 21 and a weak section 25, the load is transmitted to both the inner stiffness change section 21 and the weak section 25, making it possible to deform the inner stiffness change section 21 and the weak section 25 as intended. Furthermore, as shown in Figure 2, since the weak section 25 extends from the upper end to the lower end of the front inner member 11, the deformation in which the weak section 25 bends outward can be generated more reliably, and the intended deformation mode can be obtained.

[0076] Furthermore, since the vulnerable portion 25 deforms to protrude outward, the front side member 10 deforms to move away from devices such as the electric motor 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 these devices. Moreover, in this embodiment, the front side member 10 is located on the outer side in the vehicle width direction of the dash panel 51, below the apron side member 52 that extends forward from the outer side of the strut tower 31. Therefore, the deformation of the vulnerable portion 25 to bend outward is less likely to be hindered by the apron side member 52.

[0077] Furthermore, as described above, the front structure of this embodiment includes a strut tower 31 and a subframe 35. As shown in Figures 1, 7, and 8, 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.

[0078] 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 metal 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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. The subframe 35 and the front side member 10 are spaced apart, so that the side frame does not hinder the deformation of the front side member 10.

[0084] Furthermore, in this embodiment, the motor frame 45 is joined to the front side member 10 via a mounting bracket 48, as shown in Figure 2, and the mounting bracket 48 is joined to the lower side of the weak portion 25. As shown in Figure 4, the mounting bracket 48 is a box-shaped structure with an opening at the top and is made of a metal material.

[0085] Furthermore, in this embodiment, as shown in Figures 7 and 8, a floor panel 53 of the vehicle compartment is positioned on the rear side of the front side member 10, and a reinforcing panel 18 extending in the vehicle width direction is joined to the front of the floor panel 53. A lower cross member 40 extending in the vehicle width direction is joined to the lower side of the reinforcing panel 18, and an inner curved member 14 and an outer curved member (rear part of the rear member) are also joined thereto.

[0086] 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.

[0087] For example, in this embodiment, the inner stiffness change portion 21 is provided on the inner wall portion 11a located above and below the inner recess 11b in the front part of the front inner member 11, but it is not limited to this. For example, the inner stiffness change portion 21 may also be provided in the inner recess 11b. [Explanation of Symbols]

[0088] 1 Electric motor 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 11e1 Protruding flange portion (protruding part) 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 13f Outer flange section 14 Inner curved member 14a Inner wall 14d Bottom part 14g outer flange section 14h Inner flange section 15 Outer curved member 19 Brace 19a Front part 19b Inner side (extension) 21. Internal stiffness change section (stiffness change section) 21a Low rigidity part 21b High rigidity part 21c Through hole 21d Through hole 22. External stiffness change section (stiffness change section) 22a Low rigidity part 22b High rigidity part 25 Vulnerable parts 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 45 Motor Frame 45a Frame main body 45b Side frame section 45c Body coupling section 45d shaft member 48 Mounting bracket 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 vehicle width direction at the front of the vehicle and extending in the vehicle longitudinal direction; and a motor frame positioned below the side members and supporting an electric motor, The front portion of the inner side of the side member in the vehicle width direction is provided with a rigidity variation section, in which a plurality of low-rigidity sections and a plurality of high-rigidity sections having higher rigidity than the low-rigidity sections are alternately arranged in the longitudinal direction of the vehicle. The front structure of an electric vehicle is characterized in that the side member located on the rear side of the rigidity change section is provided with a weak section having lower rigidity than the high-rigidity section.

2. The side member has an inner wall portion facing inward in the vehicle width direction, and an outer wall portion arranged at a distance from the inner wall portion in the vehicle width direction. The stiffness-changing portion is provided at the front of the inner wall portion and the front of the outer wall portion, The front structure of an electric vehicle according to claim 1, characterized in that, in the longitudinal direction of the vehicle, the positions of the low-rigidity portion and the high-rigidity portion of the rigidity change portion of the inner wall correspond to the positions of the low-rigidity portion and the high-rigidity portion of the rigidity change portion of the outer wall.

3. The side member has a brace covering the front end, An extension is provided on the inner side of the brace in the vehicle width direction, extending toward the rear of the vehicle. The front structure of an electric vehicle according to claim 1, characterized in that the extension is joined to the side member.

4. An outer flange portion protruding in the vehicle width direction is provided on the outer side of the front part of the side member, and the brace is joined to the outer flange portion. The front structure of an electric vehicle according to claim 1, characterized in that a through hole is formed in the rigidity change portion of the side member.

5. The front structure of an electric vehicle according to claim 4, characterized in that a protruding portion is provided on the upper part of the side member located above the through hole, which protrudes upward.

6. The brace extends in the vertical direction of the vehicle, The lower part of the brace is joined to the motor frame, The front structure of an electric vehicle according to claim 3, characterized in that the front end of the motor frame is located on the vehicle-forward side from the rigidity change portion.

7. The front end of the electric motor is positioned further rearward than the front end of the rigidity change section. The front structure of an electric vehicle according to claim 1, characterized in that the front end of the motor frame is positioned further forward than the front end of the front side member.

8. The front structure of an electric vehicle according to any one of claims 1 to 7, characterized in that the rigidity changing portion has a recess and a convex portion arranged side by side in the longitudinal direction of the vehicle, the recess constitutes the low rigidity portion, and the convex portion constitutes the high rigidity portion.

9. The front structure of an electric vehicle according to any one of claims 1 to 7, characterized in that the vulnerable portion is located on the inner side of the side member in the vehicle width direction, in the middle of the vehicle in the vehicle longitudinal direction, recessed toward the outer side in the vehicle width direction, and extending in the vehicle vertical direction.

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