Vehicle undercarriage

Abstract

This lower structure of a vehicle has left and right side members 2a, 2b that extend in the vehicle front-rear direction, and a first suspension cross member 7 and a second suspension cross member 8 that extend in the vehicle width direction with an interval therebetween in the vehicle front-rear direction and are coupled to the left and right side members 2a, 2b, a front drive shaft 15 for driving the front wheels of the vehicle being disposed so as to extend in the vehicle width direction between the first suspension cross member 7 and the second suspension cross member 8, wherein a support bracket 20 that extends in the vehicle front-rear direction and supports a right front drive shaft 15a, is provided so as to couple the first suspension cross member 7 and the second suspension cross member 8.

Description

[Technical Field]

[0001] The present invention relates to a support structure for a drive shaft of a vehicle. [Background technology]

[0002] Four-wheel drive vehicles and front-wheel drive vehicles such as pickup trucks are equipped with a differential device (front differential) at the front of the vehicle. For example, in the vehicle described in Patent Document 1, power is transmitted from an engine mounted on the vehicle body to a transmission (automatic transmission mechanism) and a center differential (transfer device), which then splits the power to the front and rear wheels of the vehicle. Power is transmitted from the center differential via a rear propeller shaft (propeller shaft) to a rear differential located at the rear of the vehicle, and power is transmitted via a front propeller shaft (drive pinion shaft) to a front differential located at the front of the vehicle.

[0003] The front differential is located between the left and right front wheels and divides the power transmitted from the front propeller shaft, transmitting some of the power to the right front wheel via the right front drive shaft that extends widthwise between the left and right front wheels, and some of the power to the left front wheel via the left front drive shaft. In Patent Document 1, the front differential and the transmission are housed in a case fixed to the vehicle body, and the front differential is positioned offset in the vehicle width direction from the center position in the vehicle width direction. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-184086 Summary of the Invention [Problem to be solved by the invention]

[0005] Many frame-type vehicles are equipped with suspension cross members that extend in the vehicle width direction, located in front of and behind the left and right front drive shafts. The left and right ends of the suspension cross members are connected to the left and right side members, and suspension arms that support the front wheels are supported near the left and right ends.

[0006] In this way, in vehicles with two suspension cross members, when the front differential is located separately from the transmission, the front differential case is often fixed so as to connect the two suspension cross members.

[0007] However, if the front differential is connected to the suspension cross member at a position offset in the vehicle width direction from the center, the front differential will bear the load acting on the front suspension cross member in the event of a frontal collision, resulting in a structure with different strength on the left and right sides of the vehicle. Therefore, to prevent differences in collision resistance performance between the left and right sides in the event of an offset collision, the strength and structure of the reinforcing members must be adjusted, which poses problems such as increased design and parts costs.

[0008] The present invention has been made to solve such problems, and has as its object to provide a vehicle underbody structure with excellent crash resistance. [Means for solving the problem]

[0009] In order to achieve the above object, the vehicle understructure of the present invention includes left and right side members extending in a longitudinal direction of the vehicle and spaced apart from each other in the vehicle width direction, and a first cross member and a second cross member extending in the vehicle width direction and spaced apart from each other in the longitudinal direction of the vehicle and connected to the left and right side members, wherein a drive shaft that drives the front wheels of the vehicle is disposed to extend in the vehicle width direction between the first cross member and the second cross member, and further includes a support member extending in the longitudinal direction of the vehicle and supporting the drive shaft, the support member connecting the first cross member and the second cross member. The support member has a weak portion that is more easily bent than the front and rear portions. It is characterized by: Thus, by providing a support member that connects the first cross member and the second cross member, the collision load transmitted from the front of the side member in the event of a vehicle frontal collision can be borne by the support member together with the side member. Furthermore, the support member can be buckled to absorb the impact load during a frontal collision. The strength of the support member can also be easily adjusted, making it easy to set uniform strength on both sides of the front of the vehicle in the vehicle width direction.

[0010] Preferably, a front differential device interposed on the drive shaft and allowing differential movement of the left and right front wheels of the vehicle is connected to the first cross member and the second cross member at a position offset to one side of the vehicle width direction from the center position in the vehicle width direction, and the support member is connected to the first cross member and the second cross member at a position offset to the other side of the vehicle width direction from the center position in the vehicle width direction. As a result, at one side of the front of the vehicle in the vehicle width direction, the front differential device is structured to connect the first cross member and the second cross member, thereby improving the strength of the portion of the front of the vehicle in the vehicle width direction on that side. Also, at the other side of the front of the vehicle in the vehicle width direction, the support member is structured to connect the first cross member and the second cross member, thereby improving the strength of the portion of the front of the vehicle in the vehicle width direction on that side. Therefore, the difference in strength between the right and left sides of the front of the vehicle in the vehicle width direction can be reduced, and the offset collision resistance performance of the front of the vehicle can be made uniform on both sides.

[0012] Preferably, the weakened portion is formed on the upper surface of the support member. As a result, when a rearward load acts on the support member during a vehicle frontal collision, the support member is caused to buckle by bending downward, thereby absorbing the collision load.

[0013] Preferably, a vehicle-mounted device is provided adjacent to the support member, and the weakened portion is formed in a concave shape facing away from the vehicle-mounted device. This allows the support member to be spaced apart from the on-vehicle equipment to form the fragile portion, so that when a load acts on the support member during a frontal collision and the support member buckles, the support member is bent at the fragile portion so as to move away from the on-vehicle equipment, thereby suppressing interference between the support member and the on-vehicle equipment and protecting the on-vehicle equipment.

[0014] Preferably, the first cross member and the second cross member have reinforcing portions at their ends, and the support member is connected to the ends of the first cross member and the second cross member. This allows the support member to be connected to high strength locations on the first cross member and the second cross member, further improving the strength of one side of the front part of the vehicle in the vehicle width direction.

[0015] Preferably, a connecting member is provided that connects the drive shaft and the support member, and the weakened portion is provided forward of the vehicle from a point where the support member is connected to the connecting member. This makes it easier for the support member to bend at the weak portion when a load acts on the support member and the support member buckles during a vehicle frontal collision.

[0016] Preferably, the connection position between the connecting member and the support member is located below and on the front side of the vehicle with respect to the axis of the drive shaft. This allows the inertial force of the drive shaft and front differential device to be efficiently absorbed by the support member via the arm in the event of a frontal vehicle collision, thereby improving the impact resistance of the support portion between the drive shaft and the support member. [Effects of the Invention]

[0017] According to the vehicle undercarriage structure of the present invention, the collision load transmitted from the front of the side member during a vehicle frontal collision can be received by the side member together with the support member, thereby improving the strength against a vehicle frontal collision at the position where the support member is located. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a top view showing a schematic structure of a front lower part of a vehicle according to an embodiment of the present invention; [Figure 2] 1 is a right side view showing a schematic structure of a front lower part of a vehicle according to an embodiment of the present invention. [Figure 3] 1 is a perspective view showing a schematic structure of a right front lower part of a vehicle according to an embodiment of the present invention. [Figure 4] FIG. 2 is a perspective view showing the structure of a shaft support bracket and its fixing portion in the present embodiment; [Figure 5] FIG. 2 is an explanatory diagram showing a transmission path of an impact load at the front of a vehicle in a frontal collision. [Figure 6] FIG. 2 is an explanatory diagram showing a state in which the front part of a vehicle is crushed in a frontal collision. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a top view showing the schematic structure of the front lower part of a vehicle 1 according to one embodiment of the present invention. FIG. 2 is a right side view showing the schematic structure of the front lower part of a vehicle 1 according to this embodiment. FIG. 3 is a perspective view showing the schematic structure of the right front lower part of a vehicle 1 according to this embodiment. Note that FIG. 3 is a view of the right front lower part of a vehicle 1 as seen from below. FIG. 4 is a perspective view showing the structure of a shaft support bracket 20 (support member) and its fixing part according to this embodiment, as seen from above the left front of the shaft support bracket 20.

[0020] A vehicle 1 employing the undercarriage structure of the present invention has various body frames such as side members 2a, 2b, etc. The vehicle 1 is a four-wheel drive vehicle, and is equipped with a front differential 5 (front differential device) at the front and a rear differential (rear differential device) (not shown) at the rear.

[0021] 1, a vehicle 1 includes a pair of side members 2a, 2b that extend in the front-rear direction of the vehicle and are spaced apart in the vehicle width direction. The pair of side members 2a, 2b are connected by multiple cross members.

[0022] 1 to 4, a first suspension cross member 7 (first cross member) and a second suspension cross member 8 (second cross member) are provided at the front of vehicle 1, spaced apart in the longitudinal direction of the vehicle. The first suspension cross member 7 and the second suspension cross member 8 extend in the vehicle width direction below the side members 2a, 2b, with both ends extending upward and fixed to the left and right side members 2a, 2b.

[0023] The front ends of suspension arms 9 are supported on both ends of the first suspension cross member 7 at the front of the vehicle. The rear ends of suspension arms 9 are supported on both ends of the second suspension cross member 8 at the rear of the vehicle.

[0024] The suspension arm 9 rotatably supports a front drive shaft 15 that drives the front wheels. The front drive shaft 15 is located in the front-to-rear position of the vehicle between the first suspension cross member 7 and the second suspension cross member 8, and extends in the vehicle width direction.

[0025] The front drive shaft 15 has a right front drive shaft 15a that connects the front differential 5 to the right front wheel of the vehicle 1, and a left front drive shaft 15b that connects the front differential 5 to the left front wheel of the vehicle 1.

[0026] The right front drive shaft 15a is supported by a right suspension arm 9 that is supported at the lower part near the right ends of the first suspension cross member 7 and the second suspension cross member 8. The left front drive shaft 15b is supported by a left suspension arm (not shown) that is supported at the lower part near the left ends of the first suspension cross member 7 and the second suspension cross member 8.

[0027] The front differential 5 of the vehicle of this embodiment is disposed between the left and right side members 2a, 2b, offset to the left of the center position in the vehicle width direction. The front portion of the front differential 5 is supported near the left end of the first suspension cross member 7 via an arm 18 extending forward of the vehicle so as to be swingable in the up and down direction.

[0028] The rear portion of the front differential 5 is elastically supported on the left portion of the second suspension cross member 8 via an elastic member 19 so as to be movable in the vertical direction. Furthermore, in this embodiment, a shaft support bracket 20 is provided to support the right front drive shaft 15a. The shaft support bracket 20 has, for example, a hollow box-like cross section and extends in the fore-and-aft direction of the vehicle. Its front end is supported near the right end of the first suspension cross member 7, while its rear end is supported near the right end of the second suspension cross member 8.

[0029] The shaft support bracket 20 supports the right front drive shaft 15a at approximately the center in the front-to-rear direction via an elastic member 21 and a connecting member 22. The connecting member 22 is supported by the shaft support bracket 20 at a position below and in front of the right front drive shaft 15a.

[0030] The left and right front drive shafts 15a, 15b are rotatably housed inside a cylindrical shaft case, which is supported by a connecting member 22 and left and right suspension arms 9 and is fixed to the case of the front differential 5.

[0031] A recess 25 (weak portion) is provided in the front portion of the shaft support bracket 20, i.e., in the area between the support portion of the elastic member 21 and the first suspension cross member 7. The recess 25 is formed so that the upper surface of the shaft support bracket 20 is recessed downward. As shown in FIG. 2, when viewed from the right in the vehicle width direction, the recess 25 is located below vehicle-mounted equipment 26, such as a motor, located above the shaft support bracket 20.

[0032] Furthermore, both ends of the first suspension cross member 7 each have a vertical member 28 extending upward, and both ends of the second suspension cross member 8 each have a vertical member 29 extending upward. The upper ends of the right-side vertical members 28, 29 are connected to the right side member 2a, and the upper ends of the left-side vertical members 28, 29 are connected to the left side member 2b.

[0033] In the first suspension cross member 7, both ends of the portion extending in the vehicle width direction and the lower portion of the vertical member 28 are connected or bent vertically, and a reinforcing member 31 (reinforcing portion) is provided to cover the upper surface and front and rear surfaces of the connection or bend portion. In addition, in the second suspension cross member 8, both ends of the portion extending in the vehicle width direction and the lower part of the vertical member 29 are connected or bent vertically, and a reinforcing member 32 is provided to cover the upper surface and front and rear surfaces of the connected or bent portion.

[0034] Both ends of the shaft support bracket 20 are connected to a reinforcing member 31 on the vehicle right side of the first suspension cross member 7 and a reinforcing member 32 on the vehicle right side of the second suspension cross member 8.

[0035] Fig. 5 is an explanatory diagram showing the transmission path of impact load at the front of a vehicle during a frontal collision. Fig. 6 is an explanatory diagram showing the state in which the front of the vehicle is crushed during a frontal collision. Figs. 5 and 6 are right side views showing the schematic structure of the front lower part of the vehicle.

[0036] As described above, in the vehicle 1 of this embodiment, the front differential 5 is positioned offset to the left in the vehicle width direction from the center position in the vehicle width direction. In addition, the first suspension cross member 7 and the second suspension cross member 8 are provided in front of and behind the front differential 5 and the front drive shaft 15. Furthermore, the front part of the front differential 5 is connected to the first suspension cross member 7 via the arm 18, and the rear part of the front differential 5 is connected to the second suspension cross member 8. Therefore, at the left front part of the vehicle, the front differential 5, together with the arm 18, is structured to connect the first suspension cross member 7 and the second suspension cross member 8. This makes the left front part of the vehicle relatively strong.

[0037] Meanwhile, at the front right of the vehicle, a shaft support bracket 20 that supports the front drive shaft 15 is connected to the first suspension cross member 7 and the second suspension cross member 8. Therefore, at the front right of the vehicle, the shaft support bracket 20 connects the first suspension cross member 7 and the second suspension cross member 8.

[0038] Connecting the first suspension cross member 7 and the second suspension cross member 8 with the shaft support bracket 20 improves the strength of the right front portion of the vehicle. For example, in the event of an offset collision with the right front portion of the vehicle, as shown by the arrow in Figure 5, the load received from the impact object OS toward the rear of the front end of the side member 2a is transmitted rearward through the side member 2a, and a portion of this load is transmitted from the side member 2a in front of the front drive shaft 15 to the rear portion of the side member 2a via the vertical member 28, the shaft support bracket 20, and the vertical member 29. In other words, the collision load received at the right front portion of the vehicle is distributed and borne by the side member 2a and the shaft support bracket 20 near the fore-and-aft positions of the front drive shaft 15.

[0039] In the case of an offset collision with the left front portion of the vehicle 1, part of the load received from the collision object OS toward the rear at the front portion of the side member 2b is transmitted from the side member 2a on the front side of the front drive shaft 15 through the vertical member 28, the arm 18, the front differential 5, and the vertical member 29 to the rear portion of the side member 2a. In other words, the collision load received at the left front portion of the vehicle is distributed and received by the side member 2a, the arm 18, and the front differential 5 near the fore-and-aft positions of the front drive shaft 15.

[0040] As a result, even in a vehicle in which the front differential 5 is disposed offset to the left in the vehicle width direction, the strength and impact absorption against the offset collision load at the front right and front left parts of the vehicle can be made substantially the same, making it possible to make the offset collision resistance performance uniform on both sides.

[0041] The shaft support bracket 20 is also provided with a recess 25, which is a weak portion that is more easily bent than the front and rear portions. This allows the shaft support bracket 20 to buckle and absorb the collision load in the event of a frontal collision. The strength of the shaft support bracket 20 can also be easily adjusted, making it easy to set uniform strength on both the left and right sides of the front of the vehicle in the vehicle width direction.

[0042] Furthermore, since this recess 25 is provided on the upper surface of the shaft support bracket 20, when a rearward load acts on the shaft support bracket 20 during a frontal vehicle collision, the shaft support bracket 20 can be buckled so as to bend downward, as shown in FIG.

[0043] Furthermore, the on-vehicle equipment 26 is provided adjacent to the upper side of the shaft support bracket 20, and the recess 25 is recessed downward, that is, in a direction away from the on-vehicle equipment 26. This allows the recess 25 to be formed in the shaft support bracket 20 with a gap between it and the on-vehicle equipment 26. Therefore, in the event of a frontal vehicle collision, the shaft support bracket 20 can be buckled and the collision load can be absorbed without being obstructed by the vehicle-mounted equipment 26 arranged adjacent to and above the shaft support bracket 20.

[0044] If vehicle-mounted equipment 26, such as a motor for driving the vehicle, is arranged above the shaft support bracket 20, if the shaft support bracket 20 buckles during a frontal collision of the vehicle, it will bend downward to avoid the vehicle-mounted equipment 26, thereby protecting the relatively expensive vehicle-mounted equipment 26.

[0045] Additionally, reinforcing members 31, 32 are provided at the ends of the first suspension cross member 7 and the second suspension cross member 8, and the shaft support bracket 20 is connected to the reinforcing members 31, 32. This allows the shaft support bracket 20 to be connected to a position on the first suspension cross member 7 and the second suspension cross member 8 that has high strength, ensuring the strength of the connecting portion of the shaft support bracket 20.

[0046] In addition, the right front drive shaft 15a is supported on the shaft support bracket 20 via an elastic member 21 and a connecting member 22, and in the shaft support bracket 20, the recess 25 is located further forward of the vehicle than the connection point (support point) with the connecting member 22. As a result, when a load acts on the shaft support bracket 20 from the first suspension cross member 7 side toward the rear of the vehicle during a frontal collision, the middle portion of the shaft support bracket 20 is supported by the connecting member 22, making it easier for the shaft support bracket 20 to bend at the recess 25.

[0047] The connection position between the connecting member 22 and the shaft support bracket 20 is located below and in front of the vehicle with respect to the axis of the right front drive shaft 15a. As a result, in the event of a frontal collision, the inertial force of the front drive shaft 15 and front differential 5, which tend to move forward relative to the body frame such as the side members 2a and 2b, can be efficiently absorbed by the shaft support bracket 20 via the connecting member 22, thereby improving the impact resistance of the support portion between the front drive shaft 15 and the shaft support bracket 20 and suppressing movement of the front drive shaft 15, etc.

[0048] The present invention is not limited to the above-described embodiments. For example, the detailed structures of various components such as the shaft support bracket 20 may be changed as appropriate.

[0049] In addition, in this embodiment, the front differential 5 is disposed on the left side in the vehicle width direction of the vehicle 1, and the shaft support bracket 20 is disposed on the right side in the vehicle width direction, but they may be disposed in reverse.

[0050] Alternatively, even if the front differential 5 is located in the center of the vehicle 1 in the vehicle width direction, the shaft support brackets 20 may be arranged on the left and right sides of the front differential 5 in the vehicle width direction, and both may be arranged so as to be connected to the first suspension cross member 7 and the second suspension cross member 8. Even if the front differential 5 is located in the center of the vehicle 1 in the vehicle width direction, in the case of a vehicle in which the strength of the left and right sides of the front of the vehicle is different, the shaft support bracket 20 can be appropriately positioned to eliminate the difference in strength between the left and right sides.

[0051] Alternatively, even in a vehicle in which the front differential 5 is located in the center of the vehicle width direction of the vehicle 1 and has left and right uniformity in terms of offset collision resistance, the strength of the vehicle body between the first suspension cross member 7 and the second suspension cross member 8 can be improved by connecting the shaft support bracket 20 to the first suspension cross member 7 and the second suspension cross member 8. Furthermore, the present invention can be widely applied to vehicles with a frame structure having a first suspension cross member 7 and a second suspension cross member 8. [Explanation of symbols]

[0052] 1 vehicle 2a, 2b Side members 5 Front differential (front differential device) 7 First suspension cross member (first cross member) 8 Second suspension cross member (second cross member) 15a Right front drive shaft (drive shaft) 20 Shaft support bracket (support member) 22 Connecting member 25 Concave part (weak part) 26 Vehicle-mounted equipment 31 Reinforcing member (reinforcing part)

Claims

1. left and right side members extending in a front-rear direction of the vehicle and spaced apart from each other in a vehicle width direction; a first cross member and a second cross member extending in a vehicle width direction and spaced apart from each other in a front-rear direction of the vehicle and connected to the left and right side members, a drive shaft for driving front wheels of the vehicle is disposed so as to extend in a vehicle width direction between the first cross member and the second cross member; a support member extending in a vehicle longitudinal direction and supporting the drive shaft, the support member connecting the first cross member and the second cross member; The support member is provided with a weak portion that is more easily bent than the front and rear portions. A vehicle undercarriage characterized by:

2. a front differential device that is interposed in the drive shaft and allows differential movement of left and right front wheels of the vehicle, and is connected to the first cross member and the second cross member at a position that is offset toward one side in the vehicle width direction from a center position in the vehicle width direction; The support member is connected to the first cross member and the second cross member at a position offset toward the other side in the vehicle width direction from the center position in the vehicle width direction.

2. The vehicle undercarriage according to claim 1.

3. The weakened portion is formed on the upper surface of the support member.

2. The vehicle undercarriage according to claim 1.

4. a vehicle-mounted device provided adjacent to the support member; The weakened portion is formed in a concave shape facing away from the vehicle-mounted device.

2. The vehicle undercarriage according to claim 1.

5. the first cross member and the second cross member have reinforcing portions at their ends, The support member is connected to the ends of the first cross member and the second cross member.

3. The vehicle undercarriage according to claim 2.

6. a connecting member that connects the drive shaft and the support member, The weakened portion is provided forward of a connection point of the support member with the connecting member.

2. The vehicle undercarriage according to claim 1.

7. The connecting position between the connecting member and the support member is located below the front of the vehicle with respect to the axis of the drive shaft.

7. The vehicle undercarriage according to claim 6.

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