JP7597602B2 - Vehicle front body structure - Google Patents

Description

The present invention relates to a front body structure of a vehicle, and in particular to a mounting structure for a suspension member to a vehicle body.

In a typical passenger car, the portion of the vehicle in front of the passenger compartment is an engine compartment that houses a power unit including a prime mover such as an engine for driving the vehicle. Below the boundary between the engine compartment and the passenger compartment, a suspension member is located that holds the suspension arm in a swingable manner.

Patent document 1 discloses a front body structure for a vehicle, and shows a structure including a pair of left and right lower arms (suspension arms), a subframe (suspension members) that supports the pair of left and right lower arms so that they can swing, and a pair of left and right connecting members that connect the rear portion of the subframe to a pair of left and right floor frames (side members).

JP 2015-186960 A

Depending on the mounting structure of the suspension member to the vehicle body, the vehicle's quietness and running stability change. There is a demand for a mounting structure for the suspension member that can ensure both quietness and running stability of the vehicle.

The object of the present invention is to provide a suspension member mounting structure that ensures both quietness and driving stability of the vehicle.

The front body structure of a vehicle of the present invention comprises a suspension member having a suspension retaining portion that retains a suspension arm so that it can swing, and having a body mounting portion that is fastened to a body floor of the body at the rear of the vehicle, a suspension arm having a ball joint support portion that supports a ball joint on the outer side in the vehicle width direction, and a retaining portion that is retained by the suspension retaining portion of the suspension member on the inner side in the vehicle width direction, and a brace having a first connecting portion connected to the suspension member and a second connecting portion connected to a body front side member that is a part having higher rigidity than the body floor, wherein, in a plan view of the vehicle, the suspension retaining portion is disposed on or in the vicinity of a line connecting the ball joint support portion and the body mounting portion, the brace is disposed such that the line connecting the first connecting portion and the second connecting portion is obliquely outward in the vehicle width direction as it approaches the rear of the vehicle, and the brace has a weak portion formed in a central portion between the first connecting portion and the second connecting portion .

According to this structure, vibrations from the road surface input to the suspension member via the suspension arm can be efficiently transmitted to the body floor, which is a low-rigidity part, and the vibrations can be attenuated. In addition, since the suspension member is connected to the body front side member, which is a high-rigidity part, via the brace, driving stability can be ensured. In addition, the brace functions as a reinforcing member that suppresses deformation of the suspension member against the load input to the suspension member. In addition, according to this structure, when a collision load is transmitted to the brace, the brace can be buckled starting from the weak part.

In the front body structure for a vehicle of the present invention, the weakened portion of the brace may be a portion in which an upper surface of the brace is formed into a concave shape .

In the vehicle front body structure of the present invention, the weakened portion of the brace may be a hole provided in the brace.
In the front body structure of a vehicle of the present invention, the brace may include flanges formed extending in the longitudinal direction at both short end portions, and the weak portion of the brace may be a cut-out portion of the flange of the brace.

The present invention makes it possible to ensure both quietness and driving stability of the vehicle.

FIG. 2 is a perspective view showing a front body structure of a vehicle. FIG. 2 is a perspective view showing a suspension member. FIG. 2 is a diagram showing a schematic view of the front vehicle body structure as viewed from below. This is a cross-sectional view taken along line AA in FIG. FIG. FIG. 2 is a diagram showing a schematic side view of the front vehicle body structure. 1A and 1B are diagrams illustrating a state in which a front vehicle body structure is deformed during a frontal collision. FIG. 4 is a cross-sectional view taken along line AA of FIG. 3 during a frontal collision. FIG. 1 is a diagram for explaining how vibrations from the road are transmitted. FIG. 13 is a diagram showing a schematic diagram of the characteristics of quietness and running stability of a vehicle according to the stiffness of a brace. FIG. 13 is a perspective view showing another brace. FIG. 13 is a perspective view showing yet another brace. 4 is a diagram showing the positional relationship between a ball joint support portion, a suspension holding portion, and a vehicle body mounting portion. FIG.

Below, an embodiment of the present invention will be described with reference to the drawings. In the following description, unless otherwise specified, terms expressing directions and orientations such as front, rear, left, right, up, down, etc., refer to directions and orientations related to the vehicle. In addition, in the left-right direction (width direction) of the vehicle, the side closer to the center line extending in the front-rear direction of the vehicle is referred to as the inside in the vehicle width direction, and the farther side is referred to as the outside in the vehicle width direction. In each figure, the arrow FR points forward, the arrow UP points upward, and the arrow LH points leftward.

1 is a perspective view showing a front body structure 12 of a vehicle 10. The front body structure 12 defines an engine compartment 18 separated from a passenger compartment 16 by a dashboard 14. The engine compartment 18 houses a power unit 20 (see FIG. 6) that integrates a prime mover for driving the vehicle, such as an engine or an electric motor, a transmission, and a final reduction gear. The front body structure 12 has body front side members 22 (hereinafter simply referred to as side members 22) that are arranged to extend in the front-rear direction on the left and right. A crash box 24 is connected to the front end of each of the left and right side members 22. The side members 22 are arranged in the engine compartment 18 at approximately the center in the up-down direction of the front body structure 12, and the rear parts of the side members 22 extend downward along the dashboard 14 and then rearward under the passenger compartment 16.

A suspension member 28 that holds the suspension arm so that it can swing is disposed below the boundary between the engine compartment 18 and the passenger compartment 16. The suspension member 28 is disposed so as to bridge the left and right side members 22 and is connected to these side members 22. The suspension member 28 has a forward extension portion 30 that extends forward. The forward extension portion 30 is located below the side members 22, and the front ends of the upper and lower side members 22 and the forward extension portion 30 are connected to each other by a connecting member 32 that extends vertically. In addition, a lower crash box 34 is connected to the front end of the forward extension portion 30.

Figure 2 is a perspective view of the suspension member 28, with some of the structure of the upper surface of the suspension member 28 omitted. The suspension member 28 has a base 29 connected to the rear of the forward extension 30, and two suspension posts 38 arranged on the left and right of the front edge of the base 29. The suspension member 28 is formed from multiple sheet metal members, and the rear part of the base 29 has a structure in which metal plates are arranged above and below to form a closed space. The suspension posts 38 extend upward and outward in the vehicle width direction from the base 29 of the suspension member 28, and their upper ends form front fastening points 46 that are fastened to the side members 22.

A pair of left and right floor fastening points 40 (also called vehicle body mounting parts 40) and a pair of left and right brace fastening points 42 (also called first connecting parts 42) located forward of the floor fastening points 40 and outboard in the vehicle width direction are formed at the rear of the base 29. The floor fastening points 40 have bolt insertion holes 40a that penetrate the upper and lower metal plates, and the brace fastening points 42 have bolt insertion holes 42a that penetrate only the lower metal plate.

Figure 3 is a schematic diagram showing the front body structure 12 as viewed from below, and Figure 4 is a cross-sectional view taken along line A-A in Figure 3. The suspension member 28 is disposed below the side member 22 and floor panel 48. The front body structure 12 includes a pair of left and right braces 26 attached to the vehicle body via a brace fastening point 42 (first connecting portion 42) of the suspension member 28 and a brace fastening point 43 (also referred to as a second connecting portion 43) of the side member 22.

The side member 22 has a U-shaped cross section that is open at the top and extends in the front-rear direction, and as shown in FIG. 4, the floor panel 48 covers it from above to form a closed cross section. The side member 22 has high rigidity and forms the framework of the vehicle body. The floor panel 48 (also called the body floor 48) is provided spreading out below the passenger compartment and has lower rigidity than the side member 22. The floor panel 48 is recessed downward at the floor fastening point 40 (see FIG. 3) of the suspension member 28, and the floor fastening point 40 and the brace fastening point 43 of the side member 22 are located at approximately the same position in the vertical direction.

A bolt is inserted into each of the two floor fastening points 40 from below, and the bolt passes through a bolt insertion hole 40a (see FIG. 2) in the suspension member 28 and a bolt insertion hole (not shown) formed in the floor panel 48, and is screwed into a nut (not shown) on the floor panel 48. This connects the rear part of the suspension member 28 and the floor panel 48.

The pair of braces 26 are fastened to the vehicle body symmetrically. FIG. 5 is a perspective view of the brace 26. The brace 26 is formed by pressing a rectangular metal plate, and has a weak part 50 in the center of the longitudinal direction that is weaker than the other parts of the brace 26. The weak part 50 is a concave part on the upper surface of the brace 26. The weak part 50 functions as a breakage point when a load of a certain level or more is applied in the longitudinal direction of the brace 26 due to a frontal collision of the vehicle (see FIG. 8). Bolt insertion holes 42b, 43b are formed at both longitudinal ends of the brace 26.

As shown in FIG. 4, a bolt is inserted from below into the brace fastening point 42 of the suspension member 28, and the bolt passes through the bolt insertion hole 42b of the brace 26 and the bolt insertion hole 42a of the suspension member 28, and is screwed into a nut on the lower metal plate in the suspension member 28. A bolt is also inserted from below into the brace fastening point 43 of the side member 22, and the bolt passes through the bolt insertion hole 43b of the brace 26 and the bolt insertion hole 43a formed in the side member 22, and is screwed into a nut on the side member 22. In this way, the brace 26 extends between the rear part of the suspension member 28 and the part of the side member 22 that is further rearward of the suspension member 28, and connects them.

As shown in FIG. 3, a pair of suspension arms 36 are pivotally supported on the left and right ends of the base 29 of the suspension member 28.

Figure 6 is a schematic diagram showing the front body structure 12 as seen from the side. The upper end of the suspension post 38 of the suspension member 28 is fastened to the underside of the front part of the side member 22 to form a front fastening point 46. The forward extension part 30 of the suspension member 28 extends forward, then extends diagonally upward, and then extends forward again. The steering gear box 21 is firmly fixed to the upper surface of the base part 29 of the suspension member 28. The steering gear box 21 is a mechanism that converts the rotational motion of the steered wheels into linear motion in the left-right direction, thereby steering the front wheels. The power unit 20 is located in front of the steering gear box 21.

Next, we will explain the effects of the front body structure 12 described above.

Figure 7 is a schematic diagram showing the front body structure 12 during a frontal collision. During a frontal collision, the crash boxes 24 and lower crash boxes 34 are crushed, and the side members 22 are also deformed. Because the front end of the forward extension 30 of the suspension member 28 is located higher than its rear end, a bending moment is applied by the front collision load F, causing the forward extension 30 to bend downward. As the forward extension 30 bends downward, a downward force acts on the front edge of the base 29 of the suspension member 28, and this downward force causes the suspension post 38 to detach from the side member 22 at the front fastening point 46, and the front edge of the base 29 to move downward.

Furthermore, when the collision load F is applied to the brace 26 fastened to the suspension member 28, the brace 26 bends at its weak portion 50 (see FIG. 8), and the suspension member 28 can be moved rearward. The suspension member 28 is also fastened to the floor panel 48 at two floor fastening points 40. However, since the floor panel 48 has low rigidity, it is relatively easily deformed by the collision load F and does not significantly impede the rearward movement of the suspension member 28. In this way, the suspension member 28 is bent downward and deformed and moved backward, so that the steering gear box 21 can be retracted downward and rearward. This makes it possible to prevent the power unit 20, which is moving rearward due to the collision load F, from interfering with the steering gear box 21. The rearward movement of the power unit 20 is ensured, and therefore the collision energy can be absorbed.

In addition, according to the front body structure 12, the rear part of the suspension member 28 is fastened to the floor panel 48 at the floor fastening point 40 and is connected to the side member 22, which is the body frame, via the brace 26. This allows the vehicle to achieve both quietness and running stability. As shown in FIG. 9, vibrations from the road surface (thick black arrow) are transmitted to the suspension member 28 via the suspension arm 36. For example, if the rear part of the suspension member 28 is structured to be fastened only to the floor panel 48, the vibration transmitted to the suspension member 28 is transmitted only to the floor panel 48, which has a relatively low rigidity, and not to the body frame, thereby improving the quietness of the vehicle. However, in this structure, the rigidity of the floor panel 48 is low, so that the durability of the fastening point between the suspension member 28 and the floor panel 48 is low, and there is a problem that the fastening point is significantly deformed by the vibration input from the suspension arm 36, resulting in a decrease in running stability. On the other hand, if the rear portion of the suspension member 28 is fastened only to the side member 22, which is the body frame, the running stability can be improved, but the vibration input from the suspension arm 36 is transmitted to the body frame, and the quietness of the vehicle deteriorates. In this way, the quietness of the vehicle and the running stability are in a contradictory relationship. According to the front body structure 12 described above, the rear portion of the suspension member 28 is fastened to both the floor panel 48 and the side member 22, and these function in a complementary manner to achieve a good balance between the quietness and running stability of the vehicle.

Furthermore, in the front body structure 12 described above, the suspension member 28 is connected to the side member 22 via the brace 26. Vertical vibrations are transmitted to the suspension member 28 from the suspension arm 36, but by using the brace 26, which has low rigidity against vertical deformation, the transmission rate of vibrations from the suspension member 28 to the side member 22 can be suppressed.

Figure 10 is a diagram showing the characteristics of the quietness and running stability of the vehicle according to the rigidity of the brace 26. According to the front body structure 12 described above, as shown in Figure 10, the balance between the quietness and running stability of the vehicle can be changed by changing the rigidity of the brace 26. The rigidity of the brace 26 can be changed, for example, by increasing or decreasing the plate thickness of the brace 26, or by changing the height of the flanges 52 (see Figure 11) formed on both ends of the brace 26 in the short direction and extending in the longitudinal direction. For example, by using a brace 26 with high rigidity (for example, a brace with rigidity at the position of the star in Figure 10), a vehicle with a sporty character and relatively high running stability can be realized without making major changes to the vehicle structure.

The weak portion 50 of the brace 26 described above is a concave shape on the upper surface of the brace 26, but the weak portion 50 can have various shapes. For example, as shown in FIG. 11, a hole may be provided as the weak portion 50A of the brace 26A. Also, as shown in FIG. 12, a cut-out portion of the flange 52 may be provided as the weak portion 50B of the brace 26B.

Next, the mounting structure of the suspension arm 36 and the suspension member 28 will be described. As shown in FIG. 13, the suspension member 28 has a suspension holding portion 60 on the rear side of the vehicle and a suspension holding portion 61 on the front side of the vehicle, which hold the suspension arm 36 so that it can swing. The suspension arm 36 has a ball joint support portion 64 that supports a ball joint on the outer side in the vehicle width direction, and holding portions 66, 67 that are held by the suspension holding portions 60, 61 of the suspension member 28 on the inner side in the vehicle width direction. In a plan view of the vehicle, the suspension holding portion 60 on the rear side of the vehicle is disposed near a line 70 that connects the ball joint support portion 64 and the vehicle body mounting portion 40. The suspension holding portion 60 may be disposed on the line 70 that connects the ball joint support portion 64 and the vehicle body mounting portion 40. This structure allows vibrations from the road surface input to the suspension member 28 via the suspension arm 36 to be efficiently transmitted to the body floor 48, which is a low-rigidity portion, and the vibrations can be attenuated.

The brace 26 is arranged so that the line 72 connecting the first connecting portion 42 and the second connecting portion 43 is inclined outward in the vehicle width direction as it approaches the rear of the vehicle. In this embodiment, the first connecting portion 42 is arranged on the line 70, but the first connecting portion 42 may be arranged near the line 70. With this structure, the suspension member 28 is connected to the body front side member 22, which is a high-rigidity portion, via the brace 26, thereby ensuring driving stability. In addition, the brace 26 functions as a reinforcing member that suppresses deformation of the suspension member 28 in response to a load input to the suspension member 28.

10 vehicle, 12 front body structure, 14 dashboard, 16 passenger compartment, 18 engine compartment, 20 power unit, 21 steering gear box, 22 body front side member (side member), 24 crash box, 26, 26A, 26B brace, 28 suspension member, 29 base, 30 forward extension, 32 connecting member, 34 lower crash box, 36 suspension arm, 38 suspension post, 40 floor fastening point (vehicle body mounting portion), 40a bolt insertion hole, 42 brace fastening point (first connecting portion), 42a, 42b bolt insertion hole, 43 brace fastening point (second connecting portion), 43a, 43b bolt insertion hole, 46 front fastening point, 48 floor panel (body floor), 50, 50A, 50B weak portion, 52 flange, 60, 61 suspension retaining portion, 64 Ball joint support portion, 66, 67; retaining portion, 70, 72; wire.

Claims (4)

a suspension member having a suspension holding portion that holds the suspension arm so as to be able to swing, and having a vehicle body mounting portion that is fastened to a body floor of the vehicle body at a rear side of the vehicle;
a suspension arm having a ball joint support portion supporting a ball joint on an outer side in a vehicle width direction, and a retaining portion that is retained by the suspension retaining portion of the suspension member on an inner side in the vehicle width direction;
a brace having a first connecting portion connected to the suspension member and a second connecting portion connected to a body front side member that is a portion having a higher rigidity than the body floor,
the suspension retaining portion is disposed on or in the vicinity of a line connecting the ball joint support portion and the vehicle body mounting portion in a plan view of the vehicle;
The brace is disposed such that a line connecting the first connecting portion and the second connecting portion is obliquely outward in a vehicle width direction toward the rear of the vehicle ,
The brace has a weakened portion formed in a central portion between the first connecting portion and the second connecting portion.
Front body structure of the vehicle. The front body structure of a vehicle according to claim 1,
The weakened portion of the brace is a portion in which the upper surface of the brace is recessed.
Front body structure of the vehicle. The front body structure of a vehicle according to claim 1,
The weakened portion of the brace is a hole provided in the brace.
Front body structure of the vehicle. The front body structure of a vehicle according to claim 1,
The brace includes flanges formed at both ends in a short side direction and extending in a longitudinal direction,
The weakened portion of the brace is a portion where the flange of the brace is cut out.
Front body structure of the vehicle.

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