Vehicle subframe structure

Abstract

The present invention provides a vehicle lower frame structure. The vehicle lower frame structure (10) includes an auxiliary frame (14) extending rearward of the vehicle. The auxiliary frame (14) includes a first frame portion (41) and a second frame portion (42). The first frame portion (41) has a first bottom (51) and an outer wall portion (52) rising from the first bottom (51). The second frame portion (42) has a second bottom (56) and an inner wall portion (57) rising from the second bottom (56), the second bottom (56) and the first bottom (51) together forming a bottom (55). The auxiliary frame (14) is formed into a U-shaped cross-section by the bottom (55), the outer wall portion (52) and the inner wall portion (57).

Description

[0001] This application claims priority based on Japanese Patent Application No. 2022-004102, filed on January 14, 2022, the contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the subframe structure of vehicles. Background Technology

[0003] As a vehicle lower frame structure, a known structure includes an arm that branches off from the front side beam and extends inward in the vehicle width direction, with a passageway side reinforcement extending from the rear end of the arm toward the rear of the vehicle. The main body of the arm is formed into a U-shaped cross-section with an upward opening. In the arm, flanges extend outward from a pair of upper edges of the main body toward the outside of the main body. That is, the arm, through the main body and the pair of flanges, is formed into a top hat-shaped cross-section with an upward opening (for example, see Japanese Patent Application Laid-Open No. 2005-219521). Summary of the Invention

[0004] In the aforementioned arm section, the main body is formed with a U-shaped cross-section, while the arm section as a whole is formed with a top hat-shaped cross-section. Therefore, the cross-sectional shape of the arm section becomes complex. Consequently, it is difficult to ensure the formability of the arm section when bending it from a flat plate.

[0005] Furthermore, there are cases where increasing the rigidity of the boom can improve the rigidity of the vehicle body. However, improving the rigidity of the boom requires, for example, increasing the overall thickness of the boom plate, which hinders the achievement of vehicle lightweighting.

[0006] Furthermore, increasing the overall plate thickness of the arm to improve rigidity makes it even more difficult to ensure the formability of the arm.

[0007] The present invention provides a vehicle lower frame structure that can easily ensure formability, improve rigidity, and achieve lightweighting.

[0008] The present invention proposes the following structure.

[0009] (1) The vehicle lower frame structure of the present invention includes: a rear end portion (e.g., the rear end portion 22 in the embodiment) which constitutes the rear portion of the front side frame (e.g., the front side frame 12 in the embodiment); and an auxiliary frame (e.g., the auxiliary frame 14 in the embodiment) which is disposed inside the vehicle width direction relative to the rear end portion and extends toward the rear of the vehicle. The auxiliary frame includes a first frame portion (e.g., the first frame portion 41 in the embodiment) and a second frame portion (e.g., the second frame portion 42 in the embodiment). The first frame portion has: a first bottom portion (e.g., the first bottom portion 51 in the embodiment) which faces toward The second frame portion has: a second bottom (e.g., a second bottom 56 in the embodiment) disposed in the vehicle width direction and overlapping the first bottom in the vertical direction, thereby forming a bottom together with the first bottom; and an inner wall portion (e.g., an inner wall portion 57 in the embodiment) erected from the inner edge of the second bottom in the vehicle width direction, and having a one-sided opening shape in cross-section through the first bottom, the second bottom, the outer wall portion, and the inner wall portion.

[0010] In this way, the auxiliary frame is formed by overlapping the first bottom of the first frame portion with the second bottom of the second frame portion. That is, the auxiliary frame can be divided into two parts: the first frame portion and the second frame portion. Therefore, compared to forming the cross-sectional shape of the first frame portion and the second frame portion into a shape with one opening (e.g., a U-shaped cross-section), each frame portion can be formed into a simple cross-sectional shape. As a result, the formability of the first frame portion and the second frame portion (i.e., the formability of the auxiliary frame) can be easily ensured.

[0011] Furthermore, by overlapping the first bottom of the first frame portion with the second bottom of the second frame portion, the thickness of the bottom formed by the first and second bottoms can be increased. This improves the rigidity of the auxiliary frame. Additionally, increasing the thickness of the bottom to improve the rigidity of the auxiliary frame allows for weight reduction compared to, for example, increasing the overall thickness of the auxiliary frame.

[0012] Therefore, it can improve the rigidity of the vehicle body and achieve vehicle weight reduction.

[0013] (2) Alternatively, the first frame portion can be formed into an L-shaped cross section through the first bottom and the outer wall portion, and the second frame portion can be formed into an L-shaped cross section through the second bottom and the inner wall portion.

[0014] This configuration allows the first and second frame portions to be formed with cross-sectional shapes simpler than a U-shaped cross-section. Consequently, the formability of the first and second frame portions (i.e., the formability of the auxiliary frame) can be easily ensured.

[0015] (3) Alternatively, in the auxiliary frame, the first bottom overlaps the second bottom below.

[0016] Here, the first frame portion having a first bottom is positioned on the outer side in the vehicle width direction relative to the second frame portion having a second bottom. Furthermore, the outer wall portion rises from the outer edge of the first bottom portion on the outer side in the vehicle width direction. Therefore, the first bottom extends from the outer wall portion of the first frame portion toward the inner side in the vehicle width direction.

[0017] Based on this structure, by forming the structure described above, the stepped portion formed by the inner edge of the first bottom and the second bottom can be separated and configured to be more significantly inward in the vehicle width direction relative to the outer wall portion. Furthermore, the inner end face of the inner edge of the first bottom (in other words, the inner end face of the stepped portion) can be configured to face inward in the vehicle width direction.

[0018] Therefore, for example, in cases where water splashes from the front wheels or from the outside of the vehicle, it can prevent the splashed water from adhering to the steps. This helps to prevent rusting on the steps due to splashed water.

[0019] (4) Alternatively, the auxiliary frame may have a fixing portion for mounting a sub-frame (e.g., sub-frame 16 in the embodiment) provided at the front end of the vehicle (e.g., the front end 14a in the embodiment), and the width of the overlapping portion (e.g., the overlapping portion 65 in the embodiment) at the front end in the vehicle width direction (e.g., the first width W1 in the embodiment) is wider than the width of the rear portion (e.g., the rear portion 14b in the embodiment) extending from the front end to the rear of the vehicle.

[0020] This configuration, with its wide overlapping section, enhances the rigidity of the front end of the auxiliary frame. In other words, it allows for the fixing of the fastener to the front end of the highly rigid auxiliary frame.

[0021] Therefore, for example, by applying an impact load to the subframe during a frontal collision, the fixing part can be appropriately detached from the front end of the auxiliary frame. Thus, the drive power source mounted on the subframe can be moved downwards from the vehicle compartment along with the subframe. This prevents the front of the vehicle compartment from deforming rearwards due to the power source, thus protecting the occupants.

[0022] In contrast, if the fixed part does not detach from the subframe due to the impact load input during a frontal collision, consider the possibility that the power source mounted on the subframe moves rearward, causing the front of the passenger compartment to deform rearward. Therefore, it may be difficult to protect the occupants.

[0023] Furthermore, the width of the overlapping portion is made wide only at the front end of the auxiliary frame. Therefore, the width of the overlapping portion can be made narrow at the rear end of the auxiliary frame. As a result, the overlap between the first bottom and the second bottom can be minimized at the rear end of the auxiliary frame. Therefore, the rigidity of the front end of the auxiliary frame can be improved, and the auxiliary frame can be made lighter.

[0024] (5) Alternatively, the overlapping portion may include a first overlapping portion (e.g., the first overlapping portion 66 in the embodiment) and a second overlapping portion (e.g., the second overlapping portion 67 in the embodiment). The first overlapping portion has a plurality of first connecting portions (e.g., the first connecting portion 71 in the embodiment) formed at the front end and connected at multiple locations in the vehicle width direction. The second overlapping portion has a second connecting portion (e.g., the second connecting portion 72 in the embodiment) formed at the rear portion and connected at one location in the vehicle width direction.

[0025] With this configuration, spot welding or other connections can be made at multiple locations along the width of the first overlapping portion. Therefore, the first overlapping portion can be connected along the width of the vehicle via multiple first connecting portions. Consequently, by increasing the rigidity of the first overlapping portion, the rigidity of the front end of the auxiliary frame can be improved.

[0026] Here, a fixing part is fixed to the front end of the high-rigidity auxiliary frame. Therefore, for example, an impact load input to the subframe during a frontal collision can cause the fixing part to detach appropriately from the front end of the auxiliary frame. Thus, the drive power source mounted on the subframe can move downwards from the vehicle compartment along with the subframe. This helps to prevent the front of the vehicle compartment from deforming rearwards due to the power source, thus protecting the occupants.

[0027] Furthermore, the width of the second overlapping section is narrowed at the rear of the auxiliary frame. Therefore, in the vehicle width direction of the second overlapping section, connections such as spot welding can be reduced to a single point. This reduces welding time required to join the second overlapping sections and improves welding-based workability.

[0028] According to the solution of the present invention, formability can be easily ensured, and rigidity can be improved and lightweighting can be achieved. Attached Figure Description

[0029] Figure 1 This is a perspective view of the vehicle's lower frame structure as seen from the lower left front side of the vehicle, according to an embodiment of the present invention.

[0030] Figure 2 This is a perspective view of the vehicle's lower frame structure as seen from the upper left rear side of the vehicle in an embodiment of the present invention.

[0031] Figure 3 This is a perspective view of the embodiment of the present invention, viewed from the upper left, showing the state in which the reinforcing member is decomposed from the auxiliary frame.

[0032] Figure 4 It is along Figure 3 A sectional view taken along line IV-IV.

[0033] Figure 5 It is along Figure 3 A cross-sectional view taken along the VV line.

[0034] Figure 6 This is a perspective view of the auxiliary frame in the embodiment of the present invention, viewed from the lower left front side of the vehicle. Detailed Implementation

[0035] The following description, based on the accompanying drawings, illustrates a vehicle lower frame structure according to an embodiment of the present invention. In the drawings, arrow FR indicates the front of the vehicle, arrow UP indicates the top of the vehicle, and arrow LH indicates the left side of the vehicle. The vehicle lower frame structure is configured to be approximately symmetrical from left to right; therefore, the left and right components are labeled with the same symbols, and the description of the right-side components is omitted.

[0036] <Vehicle Subframe Structure>

[0037] Figure 1 This is a three-dimensional view of the lower frame structure 10 of the vehicle, viewed from the lower left front side. Figure 2 This is a three-dimensional view of the lower frame structure 10 of the vehicle, viewed from the upper left rear side.

[0038] like Figure 1 , Figure 2 As shown, the vehicle lower frame structure 10 is a frame structure that constitutes the skeleton of the vehicle's lower part. Specifically, the vehicle lower frame structure 10 includes, for example, a front side frame 12, an auxiliary frame (passage side frame) 14 disposed inside the front side frame 12 in the vehicle width direction, and a sub-frame 16 disposed below the front side frame 12 and the auxiliary frame 14.

[0039] The front frame 12 has a front frame body 21 that extends horizontally from the front of the vehicle toward the rear of the vehicle and a rear end portion 22 that constitutes the rear of the front frame 12. That is, the rear end portion 22 extends downward from the rear end portion 21a of the front frame body 21 toward the rear of the vehicle.

[0040] A cantilever beam 24 extending outward in the vehicle width direction is provided at the rear end 22. A lower beam 26 extends from the outer end 24a of the cantilever beam 24 toward the rear of the vehicle.

[0041] The auxiliary frame 14 is positioned inside the vehicle width direction relative to the rear end 22. The front end 14a of the auxiliary frame 14 at the front of the vehicle is connected to the rear end 22 via a connecting part 27. The auxiliary frame 14 extends along the floor passage toward the rear of the vehicle and connects to the floor frame (neither shown). Details regarding the auxiliary frame 14 are described later.

[0042] The sub-frame 16 is positioned below the front frame body 21 and the auxiliary frame 14. The front end 16a of the sub-frame 16 is fixed to the front frame body 21 from below by mounting bolts 29. The rear end 16b of the sub-frame 16 is fixed to the front end 14a of the auxiliary frame 14 from below by mounting bolts 31 (specifically, the first fixing part 44 described later). Figure 3 )).

[0043] The front end 33a of the bracket 33 is fixed to the rear end 16b of the sub-frame 16 by mounting bolts 31. The rear end 33b of the bracket 33 is fixed from below to the rear portion 14b of the auxiliary frame 14 by mounting bolts 34 (specifically, the second fixing portion 45 described later). Figure 3 )).

[0044] The subframe 16 is equipped with an engine and transmission unit, or a power source such as a drive motor, and a steering device.

[0045] <Auxiliary Frame>

[0046] Figure 3 This is a perspective view of the state in which the reinforcing member 43 is decomposed from the auxiliary frame 14, as seen from the upper left side.

[0047] Figure 4 It is along Figure 3 A sectional view taken along line IV-IV. Figure 5 It is along Figure 3 A cross-sectional view taken along the VV line.

[0048] like Figures 3-5 As shown, the auxiliary frame 14 is, for example, positioned below the lower front bulkhead panel and the floor panel (not shown). The lower front bulkhead panel is, for example, a panel that separates the engine compartment (power source compartment) from the passenger compartment. The floor panel is a panel that forms the floor portion of the passenger compartment.

[0049] The auxiliary frame 14 includes: a first frame portion 41 disposed on the outer side in the vehicle width direction; a second frame portion 42 disposed on the inner side in the vehicle width direction; a reinforcing member 43 disposed on the top; a first fixing portion (fixing portion) 44 disposed at the front end portion 14a of the auxiliary frame 14; and a second fixing portion 45 disposed at the rear portion 14b of the auxiliary frame 14. The main body of the auxiliary frame 14 is divided into the first frame portion 41 and the second frame portion 42.

[0050] <First Frame Section, Second Frame Section>

[0051] The first frame portion 41 forms the frame portion on the outer side in the vehicle width direction of the auxiliary frame 14. The first frame portion 41 has: a first bottom portion 51 horizontally disposed in the vehicle width direction; an outer wall portion 52 erected from the outer edge 51a of the first bottom portion 51 on the outer side in the vehicle width direction; and a first flange 53 extending outward from the upper edge 52a of the outer wall portion 52 in the vehicle width direction.

[0052] The first frame portion 41 is formed into an L-shaped cross-section through the first bottom portion 51 and the outer wall portion 52. In addition, the first frame portion 41 is formed into a crankshaft-shaped cross-section through the first bottom portion 51, the outer wall portion 52 and the first flange 53.

[0053] The second frame portion 42 forms a frame portion on the inner side of the auxiliary frame 14 in the vehicle width direction. The second frame portion 42 has: a second bottom portion 56 horizontally disposed in the vehicle width direction; an inner wall portion 57 erected from the inner edge 56a of the second bottom portion 56 in the vehicle width direction; and a second flange 58 extending inward in the vehicle width direction from the upper edge 57a of the inner wall portion 57. The second bottom portion 56 overlaps with the first bottom portion 51 in the vertical direction. Specifically, the second bottom portion 56 overlaps with the first bottom portion 51 on top.

[0054] Thus, the main body of the auxiliary frame 14 is formed by the first frame portion 41 and the second frame portion 42. In this way, by dividing the main body of the auxiliary frame 14 into the first frame portion 41 and the second frame portion 42, the first frame portion 41 can be formed into a cross-sectional shape that is simpler than the U-shaped or top hat-shaped cross-section of the auxiliary frame 14.

[0055] Figure 6 This is a three-dimensional view of the auxiliary frame 14 as seen from the lower left side of the front of the vehicle.

[0056] like Figures 4-6As shown, the first bottom 51 of the first frame portion 41 overlaps below the second bottom 56 of the second frame portion 42. By overlapping the first bottom 51 and the second bottom 56 in the vertical direction, the bottom 55 of the auxiliary frame 14 is formed by the first bottom 51 and the second bottom 56. The bottom 55 overlaps the first bottom 51 and the second bottom 56, thereby creating a thicker structure. In this state, a stepped portion 62 is formed at the bottom 55 through the inner edge 51b of the first bottom 51 and the second bottom 56.

[0057] Here, the first frame portion 41, having a first bottom 51, is positioned on the outer side in the vehicle width direction relative to the second frame portion 42, having a second bottom 56. Furthermore, the outer wall portion 52 rises from the outer edge 51a of the first bottom 51 in the vehicle width direction. Therefore, the first bottom 51 extends from the outer wall portion 52 of the first frame portion 41 toward the inner side in the vehicle width direction.

[0058] Therefore, the step portion 62 is positioned relatively far apart from the outer wall portion 52 in the vehicle width direction. Furthermore, the inner end face 51c of the inner edge 51b of the first bottom 51 (in other words, the inner end face 51c of the step portion 62) is positioned inward in the vehicle width direction.

[0059] return Figures 3-5 The second frame portion 42 is formed into an L-shaped cross-section via the second bottom portion 56 and the inner wall portion 57. Furthermore, the second frame portion 42 is formed into a crankshaft-shaped cross-section via the second bottom portion 56, the inner wall portion 57, and the second flange 58. That is, by dividing the main body of the auxiliary frame 14 into the first frame portion 41 and the second frame portion 42, the second frame portion 42 of the auxiliary frame 14 can be formed into a simpler cross-sectional shape than a one-sided open cross-section (U-shaped cross-section) or a top hat-shaped cross-section.

[0060] The auxiliary frame 14 is formed into a U-shaped cross-section through the bottom 55, the outer wall portion 52, and the inner wall portion 57. In other words, the bottom 55 (first bottom 51, second bottom 56), the outer wall portion 52, and the inner wall portion 57 form a shape with one side open in cross-section. Hereinafter, the part of the auxiliary frame 14 that is formed into a U-shaped cross-section through the bottom 55, the outer wall portion 52, and the inner wall portion 57 is sometimes referred to as the "U-shaped cross-section portion 61".

[0061] The U-shaped cross-section 61 has a more complex cross-sectional shape compared to the first frame section 41 and the second frame section 42.

[0062] In the U-shaped cross-section 61, the first flange 53 extends outward from the upper edge 52a of the outer wall portion 52 in the vehicle width direction. Additionally, in the U-shaped cross-section 61, the second flange 58 extends inward from the upper edge 57a of the inner wall portion 57 in the vehicle width direction. Therefore, the auxiliary frame 14 is formed into a top hat shape by the U-shaped cross-section 61, the first flange 53, and the second flange 58. The auxiliary frame 14 has a more complex cross-sectional shape compared to the first frame portion 41 and the second frame portion 42.

[0063] For example, the lower front panel and bottom plate (not shown) are connected from above to the first flange 53 and the second flange 58. Thus, the auxiliary frame 14 forms a closed section through the U-shaped section 61 and the lower front panel and bottom plate. This improves the rigidity of the auxiliary frame 14.

[0064] <Overlapping parts>

[0065] The auxiliary frame 14 forms an overlapping portion 65 by overlapping the first bottom 51 and the second bottom 56 in the vertical direction. The overlapping portion 65 has a first overlapping portion 66 and a second overlapping portion 67. The first overlapping portion 66 is formed at the front end 14a of the auxiliary frame 14 in front of the vehicle. The first width (width in the vehicle width direction) W1 of the first overlapping portion 66 is wider in the vehicle width direction than the second width W2 of the second overlapping portion 67 in the vehicle width direction.

[0066] Furthermore, the first overlapping portion 66 has a plurality of (two in the embodiment) first connecting portions 71 in the vehicle width direction (see also...). Figure 6 The first connecting portion 71 is connected by, for example, spot welding. In this embodiment, two portions are described as examples of multiple connecting portions, but the connecting portions are not limited to two portions. The first overlapping portion 66 is connected by multiple first connecting portions 71 with a gap in the vehicle's longitudinal direction.

[0067] The second overlapping portion 67 is formed in the auxiliary frame 14 at the rear portion 14b extending from the front end portion 14a toward the rear of the vehicle. In other words, the second overlapping portion 67 is the portion extending from the first overlapping portion 66 toward the rear of the vehicle. The second width W2 of the second overlapping portion 67 is narrower than the first width W1 of the first overlapping portion 66 in the vehicle width direction.

[0068] The second overlapping portion 67 has a second connecting portion 72 in the vehicle width direction (see also...). Figure 6 The second connecting portion 72 is connected, for example, by spot welding. The second overlapping portion 67 is connected by a plurality of second connecting portions 72 with gaps in the longitudinal direction of the vehicle.

[0069] Here, as Figure 6As shown, for example, the auxiliary frame 14 has a pair of recesses (e.g., reinforcing ribs) 75, 76 formed at the bottom 55 of the front end portion 14a. The pair of recesses 75, 76 are formed at the bottom 55 of the front end portion 14a in an upward recessed manner. The pair of recesses 75, 76 are arranged with a gap in the vehicle's longitudinal direction and extend in the vehicle width direction. Thus, the front end portion 14a of the auxiliary frame 14 is reinforced by the pair of recesses 75, 76.

[0070] like Figure 2 , Figure 3 As shown, the front end portion 14a of the auxiliary frame 14 is connected to the rear end portion 22 via a connecting portion 27. The connecting portion 27 engages with the front end portion 14a of the auxiliary frame 14 from above. The reinforcing member 43 is connected to the front end portion 14a of the auxiliary frame 14 from above. Thus, the front end portion 14a of the auxiliary frame 14 is reinforced by the reinforcing member 43.

[0071] <First fixing part, second fixing part>

[0072] The first fixing part 44 is provided at the front end 14a of the auxiliary frame 14 at the front of the first overlapping part 66 and near the first overlapping part 66. The first fixing part 44 is provided at the connecting part 27 and the reinforcing member 43. The first fixing part 44 is, for example, a part with a mounting bolt 31 (see reference) Figure 1 A sleeve with a through hole 44a that can pass through from below.

[0073] Similar to the first fixing part 44, the second fixing part 45, for example, uses a mounting bolt 34 (see reference). Figure 1 A sleeve with a through hole 45a that can pass through from below.

[0074] like Figure 1 , Figure 2 As shown, the rear end 16b of the sub-frame 16, together with the front end 33a of the bracket 33, is mounted from below to the first fixing part 44 by mounting bolts 31. The rear end 33b of the bracket 33 is mounted from below to the second fixing part 45 by mounting bolts 34.

[0075] As explained above, in the vehicle lower frame structure 10 of the embodiment, such as Figures 3-5 As shown, the main body of the auxiliary frame 14 is divided into two parts: a first frame portion 41 and a second frame portion 42. The auxiliary frame 14 is formed by overlapping the first bottom 51 of the first frame portion 41 and the second bottom 56 of the second frame portion 42 in the vertical direction. By dividing the auxiliary frame 14 into the first frame portion 41 and the second frame portion 42, the first frame portion 41 and the second frame portion 42 can be formed into a simpler cross-sectional shape than the auxiliary frame 14, such as a U-shaped or top-hat-shaped cross-section.

[0076] Specifically, the first frame portion 41 can be formed into an L-shaped cross-section, which is simpler than the U-shaped cross-section of the auxiliary frame 14, by means of the first bottom portion 51 and the outer wall portion 52. The first frame portion 41 can be formed into a crankshaft-shaped cross-section, which is simpler than the top hat-shaped cross-section of the auxiliary frame 14, by means of the first bottom portion 51, the outer wall portion 52, and the first flange 53.

[0077] The second frame portion 42 can be formed into an L-shaped cross-section, which is simpler than the U-shaped cross-section of the auxiliary frame 14, through the second bottom portion 56 and the inner wall portion 57. The second frame portion 42 can be formed into a crankshaft-shaped cross-section, which is simpler than the top hat-shaped cross-section of the auxiliary frame 14, through the second bottom portion 56, the inner wall portion 57, and the second flange 58.

[0078] Therefore, the formability of the first frame portion 41 and the second frame portion 42 (i.e., the formability of the auxiliary frame) can be easily ensured.

[0079] The first bottom 51 of the first frame portion 41 overlaps with the second bottom 56 of the second frame portion 42, thereby forming a thicker bottom 55 by the thickness of the first bottom 51 and the second bottom 56. This increases the rigidity of the auxiliary frame 14. By increasing the thickness of the bottom 55 to improve the rigidity of the auxiliary frame, a lighter auxiliary frame 14 can be achieved compared to, for example, increasing the overall thickness of the auxiliary frame 14.

[0080] Therefore, it can improve the rigidity of the vehicle body and achieve vehicle weight reduction.

[0081] like Figures 3-6 As shown, the first bottom 51 and the second bottom 56 overlap, thereby forming a stepped portion 62 at the bottom 55 through the inner edge 51b of the first bottom 51 and the second bottom 56. The stepped portion 62 is configured to be significantly separated from the outer wall portion 52 in the vehicle width direction. Furthermore, the inner end face 51c of the inner edge 51b of the first bottom 51 (in other words, the inner end face 51c of the stepped portion 62) is configured to face inward in the vehicle width direction.

[0082] Therefore, for example, in cases where water splashes from the front wheel (not shown) or from the outside of the vehicle, the splashed water is less likely to adhere to the step 62. This helps to prevent rusting of the step 62 due to splashed water.

[0083] like Figure 1 , Figure 3 , Figure 6 As shown, a first fixing part 44 is provided at the front end 14a of the auxiliary frame 14, and a sub-frame 16 is mounted on the first fixing part 44. At the front end 14a of the auxiliary frame 14, the first width W1 of the first overlapping part 66 (refer to...) Figure 4The second width W2 of the second overlapping portion 67 (refer to) Figure 5 The width of the first overlapping portion 66 is increased. Therefore, the rigidity of the front end portion 14a of the auxiliary frame 14 can be improved by means of the first overlapping portion 66. That is, the first fixing portion 44 can be fixed to the front end portion of the auxiliary frame 14 with high rigidity.

[0084] Therefore, for example, the impact load input to the subframe 16 during a frontal collision can cause the first fixing part 44 to detach appropriately from the front end 14a of the auxiliary frame 14. Thus, the drive power source (not shown) mounted on the subframe 16 can move downwards from the vehicle compartment along with the subframe 16. This helps to prevent the front of the vehicle compartment from deforming rearwards due to the power source, thus protecting the occupants.

[0085] In contrast, if the first fixing part 44 does not detach from the front end 14a of the auxiliary frame 14 due to the impact load input to the sub-frame 16 during a frontal collision, consider the possibility that the power source mounted on the sub-frame 16 moves rearward, causing the front of the passenger compartment to deform rearward. In this case, it may be difficult to protect the occupants.

[0086] Furthermore, the first width W1 of the first overlapping portion 66 in the overlapping portion 65 is formed wide at the front end portion 14a of the auxiliary frame 14. Therefore, the second width W2 of the second overlapping portion 67 can be formed narrow at the rear portion 14b of the auxiliary frame 14. As a result, the overlap between the first bottom 51 and the second bottom 56 can be minimized at the rear portion 14b of the auxiliary frame 14. Therefore, the rigidity of the front end portion 14a of the auxiliary frame 14 can be improved, and the auxiliary frame 14 can be made lighter.

[0087] At the front end portion 14a of the auxiliary frame 14, the first width W1 of the first overlapping portion 66 is formed to be wide. Therefore, in the vehicle width direction of the first overlapping portion 66, it is possible to perform connections such as spot welding at multiple locations (two locations in the embodiment). As a result, the first overlapping portion 66 can be connected in the vehicle width direction by multiple first connecting portions 71. Consequently, the rigidity of the front end portion 14a of the auxiliary frame 14 can be improved by increasing the rigidity of the first overlapping portion 66.

[0088] Here, a first fixing part 44 is fixed to the front end 14a of the high-rigidity auxiliary frame 14. Thus, for example, the first fixing part 44 can be appropriately detached from the front end 14a of the auxiliary frame 14 by the impact load input to the sub-frame 16 during a frontal collision. Therefore, the drive power source (not shown) mounted on the sub-frame 16 can be moved downwards from the vehicle compartment along with the sub-frame 16. This helps to prevent the front of the vehicle compartment from deforming rearwards due to the power source, thus protecting the occupants.

[0089] In the rear portion 14b of the auxiliary frame 14, the second width W2 of the second overlapping portion 67 is made narrow. Therefore, in the vehicle width direction of the second overlapping portion 67, connections such as spot welding can be suppressed into a single second connection portion 72. As a result, welding time for joining the second overlapping portions 67 can be reduced, and welding-based workability can be improved.

[0090] It should be noted that the technical scope of the present invention is not limited to the aforementioned embodiments, and various modifications can be made without departing from the spirit of the present invention.

[0091] Furthermore, without departing from the spirit of the present invention, the constituent elements in the foregoing embodiments can be appropriately replaced with well-known constituent elements, and the foregoing variations can also be appropriately combined.

Claims

1. A vehicle subframe structure, characterized in that, The vehicle's lower frame structure includes: The rear end forms the rear part of the front frame and extends toward the rear of the vehicle. An auxiliary frame is disposed inside the vehicle width direction relative to the rear end and extends along the floor passage toward the rear of the vehicle. as well as The subframe is positioned below the front frame. The auxiliary frame includes a first frame portion and a second frame portion. The first frame portion has: The first bottom section is positioned facing the width of the vehicle; and The outer wall portion rises from the outer edge of the first bottom portion in the vehicle width direction. The second frame part has: The second bottom is positioned in the vehicle width direction and overlaps with the first bottom in the vertical direction, thereby forming a bottom together with the first bottom; as well as The inner wall portion rises from the inner edge of the second bottom portion in the vehicle width direction. The first bottom, the second bottom, the outer wall portion, and the inner wall portion form a square opening in cross-section. The front end of the sub-frame is fixed to the front side frame, and the rear end of the sub-frame is fixed to the auxiliary frame.

2. The vehicle subframe structure according to claim 1, characterized in that, The first frame portion is formed into an L-shaped cross-section through the first bottom portion and the outer wall portion. The second frame portion is formed into an L-shaped cross section through the second bottom portion and the inner wall portion.

3. The vehicle subframe structure according to claim 1, characterized in that, In the auxiliary frame, the first bottom overlaps the second bottom below.

4. The vehicle subframe structure according to claim 1, characterized in that, The auxiliary frame has a fixing part for mounting the sub-frame located at the front end of the vehicle. The overlapping portion of the first bottom and the second bottom is wider in the vehicle width direction at the front end than the width in the vehicle width direction at the rear portion extending from the front end toward the rear of the vehicle.

5. The vehicle subframe structure according to claim 4, characterized in that, The overlapping portion includes a first overlapping portion and a second overlapping portion. The first overlapping portion has a plurality of first connecting portions formed at the front end and connected at multiple locations in the vehicle width direction. The second overlapping portion has a second connecting portion formed in the rear portion and connected at one location in the vehicle width direction.

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