Suspension support structure

A suspension support structure has left and right suspension arms which are joined to and supported by a first cross member disposed so as to extend along the vehicle width direction and a second cross member disposed so as to extend along the vehicle width direction in the rear of the first cross member. The first cross member has a first intermediate part, and two first end parts which extend forward at an inclination to the vehicle body from the both ends of the first intermediate part and are supported at the vehicle body side. The second cross member has a second intermediate part, and two second end parts which extend rearward at an inclination to the vehicle body from the both ends of the second intermediate part and are supported at the vehicle body side.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a suspension support structure that joins and supports left and right suspension arms by cross members.

2. Description of the Related Art

In a conventional suspension support structure, as shown inFIG. 9of the accompanying drawings, suspension arms103are joined to and supported by first and second cross members101,102disposed so as to be substantially parallel to the vehicle width direction, both ends of each of the cross members101,102being fixed to a side frame (not shown in the drawing). The first and second cross members101,102are linked by two struts104,105, which are disposed so as to be substantially parallel to the front and back direction of the vehicle, thereby forming, with the first and second cross members101,102, a substantially rectangular overall shape. In the case in which a vehicle having the suspension support structure shown inFIG. 9is braked when traveling in a left direction inFIG. 9, if the right driven wheel (not shown in the drawing) rides up on sand or ice so that it spins, tire106receives a rearward-directed force107from the road surface, and forces108,109act in opposite directions along the vehicle width direction at the linking part between the first and second cross members101,102and the suspension arms103. There is a danger that these external forces108,109will cause a deformation in the rectangular structure formed by the first and second cross members101,102and the struts104,105, such as shown by the double-dot-dashed line in the drawing. For this reason, there arises the need to provide some partial reinforcement at the joining parts110,111,112, and113between the first and second cross members101,102and the struts104,105, so as to establish rigidity in the rectangular structure to suppress this deformation. Although such reinforcement can be eliminated by making the first and second cross members and struts as one piece, if this is done there is an inherent reduction in the dimensional accuracy because of the increase in the size of the structure. For this reason, there is a danger that there is an increase in the chance of a relative position offset between the cross members and the side frame when these elements are assembled, leading to complicating assembly.

SUMMARY OF THE INVENTION

Accordingly, considering the above-noted situation, it is an object of the present invention to provide a low-cost, lightweight suspension support structure that establishes rigidity, without requiring partial reinforcement, and with quality assembly.

In order to achieve the above-noted object, in as suspension support structure according to the present invention the left and right suspension arms are joined to and supported by a first cross member, which is disposed along the vehicle width direction, and a second cross member, which is disposed along the vehicle width direction in the rear of the first cross member. The first cross member has a first intermediate part, and two first end parts which extend from two ends of the first intermediate part toward the front of the vehicle at an inclination and are supported at the vehicle body. The second cross member has a second intermediate part which is joined to the first intermediate member, and two second end parts which extend from two ends of the second intermediate part toward the rear of the vehicle at an inclination and are supported at the vehicle body.

In the above-noted suspension support structure, the first intermediate part of the first cross member and the second intermediate part of the second cross member are joined, the two first end parts, left and right, from the ends of the first intermediate part at an inclination toward the front at are each supported at the vehicle body, and the two second end parts, left and right, from the ends of the second intermediate part at an inclination toward the rear at each supported at the vehicle body. The first cross member and second cross member, which join and support the suspension arms, therefore, form a substantially overall X-shape.

For example, in the case in which the vehicle transitions from a running condition to the braked condition, because if one of the driven wheels rides up on sand or ice so that it spins, the tire of the other driven wheel receives a rearward-directed force, forces acting in opposite directions along the vehicle width direction act upon the first cross member and the second cross member.

In contrast to the above, in the suspension support structure of the present invention because the first cross member and the second cross member form an substantially overall X-shape, even in forces in opposite directions act upon the first and second cross members, these are appropriately supported by the first end parts, left and right, which extend obliquely forward and the second end parts, left and right, which extend obliquely rearward. It is therefore possible without requiring partial reinforcement, to rigidly support the forces acting upon the first and second cross members.

The suspension support structure of the present invention is configured so that the first cross member and the second cross member are joined at both the first and second intermediate parts or, stated differently, it is configured so that the substantially overall X-shape is divided into two members. For this reason, compared to the case in which the overall structure is configured from a single member, each member is reduced in size, thereby making it possible to achieve the required dimension accuracy when manufacturing. It is therefore difficult for relative positional offset to occur when the first and second cross members are assembled to the vehicle body, thereby achieving quality assembly.

Additionally, because partial reinforcement is not required, it is possible to reduce cost and reduce the weight of the structure.

In the above-noted suspension support structure, the first intermediate part of the first cross member and the second intermediate part of the second cross member may be disposed in mutual opposition with a space therebetween and joined by a joining member.

In this configuration, although the first and second intermediate parts extending in the vehicle width direction, and the first and second end parts extending at an inclination, are bent or curved and connected, it is possible to reduce the bending angle of the connection part to the extent that the two intermediate parts are separated. For this reason, it is possible to reduce the individual loss of strength in the first cross member or second cross member (material) caused by the extension in a bent or curved manner, thereby further improving the overall rigidity of the structure.

It is alternatively possible to have a configuration in which the joining member can freely change the distance between the first intermediate part and the second intermediate part. Specifically, for example, it is possible to have the joining member held by bolts to the first intermediate part and the second intermediate part, and to provide bolt holes elongated in the front and back direction of the vehicle in joining member.

In this configuration, even if a dimensional error occurs in the first and second cross members at the time of fabrication, it is possible for this error to be absorbed by changing the distance between the first and second intermediate parts. There is therefore an improvement in the quality of the assembly of the first and second cross members into the car body.

Additionally, it is possible to fix a rack bracket supporting a steering rack unit for transmitting steering wheel operations to the left and right wheels at either one or more locations of the first end parts of the first intermediate part or the second end parts of the second intermediate part.

In this configuration, it is possible by the rack bracket to reduce individual loss of strength in the first cross member or second cross member (material) due to the first and second intermediate parts and the first and second end parts being connected in a bent or curved manner, thereby further improving the overall rigidity of the structure.

These and other objects and features of the present invention are made obvious by the illustrative embodiments described below in connection with the accompanying drawings, or are indicated in the attached claims. Additionally, other various advantages not referred to explicitly herein will occur to persons skilled in the art upon employing the invention in practice.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Various embodiments of the present invention are described below with reference to accompanying drawings. It is to be noted that the same or similar reference numerals are applied to the same or similar parts and elements throughout the drawings, and that descriptions of same or similar parts already described will be omitted or simplified.

In the descriptions below, the term front and back direction refers to the front and back direction of the vehicle, and the term left and right direction refers to the left and right direction in the view facing toward the front of the vehicle from therewithin. The arrow Ft in the accompanying drawings indicates the front direction of the vehicle.

As shown inFIG. 1, at the bottom part of the body of a vehicle having a chassis frame, a pair of side members1, left and right, are provided as the chassis frame so as to extend along the front and back direction of the vehicle at the left and right sides in the vehicle width direction. Each side member1has a substantially U-shaped cross-section opening toward to the inside in the vehicle width direction.

Brackets2are fixed to each of the left and right side members1. Each bracket2has a mounting plate3connected to the bottom wall under surface of the each side member1, and as shown inFIG. 2, a front leg part4extending downward from the front part of each mounting plate3, and a rear leg part5extending downward from the rear part of the each mounting plate3.

Left and right suspension arms7(only the one on the right side in the vehicle advancing direction being shown inFIG. 1) extending farther outside than the side members1in the vehicle width direction and supporting the front wheels6(only the one on the right side in the vehicle advancing direction being shown inFIG. 1) are tightened and fixed onto the front leg part4and the rear leg part5of each bracket2. The left and right suspension arms7are substantially V-shaped, the two end parts of each being tightened and fixed respectively to each of the front and rear leg parts4and5, and the portions extending outward in the vehicle width direction from the two end parts and crossing being joined to the front wheels6.

Between the front leg parts4of the left and right brackets2, a first cross member8having a cross-section that is substantially U-shaped opening downward, is provided along the vehicle width direction. The first cross member8has a first intermediate part9, which is disposed along the vehicle width direction, and two first end parts10, which extend from two ends of the first intermediate part9. Each of the first end parts10has an extension part11, which extends from the first intermediate part9, bending in a curve forward at inclination to the vehicle, and an end12, which extends from the extension part11, bending in a curve toward the outside along the vehicle width direction. The left and right ends12are tightened and fixed to the front leg parts4of the left and right brackets2, respectively.

Between the rear leg parts5of the left and right brackets2, a second cross member13having a cross-section that is substantially U-shaped opening downward, is provided along the vehicle width direction in the rear of the first cross member8. The second cross member13has a second intermediate part14, which is disposed along the vehicle width direction at a distance from the first intermediate part9in the rear of it, and two end parts15, which extend from the two ends of the second intermediate part14. Each of the second end parts15has an extension part16, which extends from the second intermediate part14, bending in a curve rearward at an inclination to the vehicle, and an end17, which extends from the extension part16, bending in a curve toward the outside along the vehicle width direction. The left and right ends17are tightened and fixed to the rear leg parts5of the left and right brackets2, respectively.

The tightening structure between the bracket2and the first and second cross members8,13is described below in further detail, with reference to FIG.3.

As shown inFIG. 3, on the lower inner end parts of the front leg part4and the rear leg part5of the bracket2is fixed a pair of mutually opposing cross member mounting plates18,19, respectively, extending inward in the vehicle width direction. The ends12,17of the first and second cross members8,13are inserted between the mounting plates18,19, respectively, and tightened to the mounting plates18,19by bolts and nuts (not shown in the drawing).

The first and second cross members8,13are thus supported by the side members1of the vehicle body via the brackets2, and join and support the left and right suspension arms7.

The first intermediate part9of the first cross member8and the second intermediate part14of the second cross member13, which are disposed opposite to each other at a distance are joined by a joining member20. Specifically, as shown inFIG. 3, a first flange part21, which protrudes from the rear end of the first intermediate part9rearward to the second intermediate part14, is formed on the first intermediate part9, and a second flange part22, which protrudes from the front end of the second intermediate part14forward to the first intermediate part9, is formed on the second intermediate part14. The joining member20is disposed on the first and second flange parts21,22so as to span across the flange parts21,22. Bolt holes23,24are provided in the flange parts21,22, respectively, and two each of bolt insertion holes27,28are provided at the front and back in the joining member20. Bolts25,26, which are inserted through the bolt insertion holes27,28, are screwed into the bolt holes23,24, thereby tightening and fastening the joining member20to the first and second cross members8,13.

As shown inFIG. 4, the two bolt insertion holes28at the rear side of the vehicle are elongated in the front and back direction of the vehicle. By these elongated holes, it is possible to vary and adjust the distance between the end12of the first cross member8and the end17of the second cross member13in accordance with the priorly established distance L (shown inFIG. 3) between the mounting plate18at the rear of the front leg part4and the mounting plate19at the front of the rear leg part5. It should be noted that the bolts25,26are not shown in FIG.4.

As shown in FIG.5andFIG. 6, a steering rack unit29for transmitting steering wheel operations to the left and right wheels6(only the right of which is shown inFIG. 1) is disposed above the first cross member8. The steering rack unit29has a steering rack (not shown in the drawing), which meshes with a pinion gear (not shown in the drawing) on the end of a steering shaft (not shown in the drawing), and a rack tube30, which covers the steering rack. Tie rods31which extend from both ends of the steering rack are joined to left and right knuckle arms32(only the right of which are shown in FIG.5and FIG.6). It should be noted that the suspension arm7is not shown in FIG.6.

Rack brackets33are fixed to the extension parts11of the left and right end parts10of the first cross member8, and the rack tube30is placed on, joined and fixed to the rack brackets33. As shown inFIG. 2, the rack bracket33has a cross-section that is substantially U-shaped opening downward, and is disposed along the front and back direction of the vehicle so as to intersect with the first end part10. As shown inFIG. 7, two grooves35into which are inserted the opposing walls34of the rack bracket33, are formed in each end part10. By the opposing walls34being inserted and welded into the grooves35, the rack bracket33is fixed to the first end part10.

The operation of this embodiment of the present invention is described below.

When the tire6aof the front wheel6receives an inward-directed or outward-directed force in the vehicle width direction while the vehicle is running, this external force acts on the first and second cross members8,13via the suspension arms7. When this occurs, because the forces acting on the first and second cross members8,13are in the same direction, these forces are reliably dispersed and supported by the side member1and the first and second cross members8,13.

In the case, for example, in which the vehicle is braked from the running condition, if the front left wheel (one of the left and right driven wheels, not shown in the drawing) rides up onto sand or ice so that it spins, the tire6aof the front right wheel (the other of the left and right driven wheels) receives a rearward-directed force, such as shown by the arrow40in FIG.1. This external force acts on the first and second cross members8,13via the suspension arms7. When this occurs, the forces acting on the first and second cross members8,13are directed in mutually opposite directions (the directions indicated by the arrows41and42in FIG.1).

In contrast to the above, in the present invention as shown inFIG. 1the first intermediate part9of the first cross member8and the second intermediate part14of the second cross member13are joined via the joining members20, the two left and right first end parts10extend from the two ends of the first intermediate part9toward the front at an inclination to the vehicle body and are each supported by the vehicle body, and the two left and right second end parts15extend from the two ends of the second intermediate part14toward the rear at an inclination to the vehicle body and are each supported by the vehicle body. That is, the first cross member8and the second cross member13joining and supporting the left and right suspension arms7have an overall form that is substantially X-shaped via the joining members20.

Therefore, even if mutually opposing forces41,42act upon the first and second cross members8,13, the left and right first end parts10extending forward at an inclination and the left and right second end parts15extending rearward at an inclination support these forces properly. It is therefore possible to firmly support the forces acting on the first and second crossmembers8,13without the need for partial reinforcement, thereby enabling simplification of the structure and a reduction in cost and weight of the structure.

Not only when the vehicle is braked but also when the vehicle is in the running condition, if the front left wheel (not shown in the drawing) rides up onto sand or ice, the tire6aon the front right wheel6will receive a forward-directed force from the road surface (direction opposite to that shown by the arrow40of FIG.1), and forces in mutually opposing directions (directions opposite to those indicated, respectively by arrows41and42inFIG. 1) will act on the first and second cross members8,13. In this case as well, there is firm support of the forces acting on the first and second cross members8,13.

The support structure according to this embodiment of the present invention has a configuration in which the first cross member8and the second cross member13are joined via the joining members20at both intermediate parts (the first and second intermediate parts9and14) or, stated differently, the configuration is such that the overall structure, which is substantially X-shaped, is divided into two members, these being the first cross member8and the second cross member13. For this reason, compared to the case in which the overall structure is configured from a single member, there is a reduction in size of each member, and achievement of the desired dimensional accuracy at the time of fabrication. Therefore, it is difficult for relative positional offset to occur when the first and second cross members8,13are assembled to the vehicle body, thereby achieving quality assembly.

The first intermediate part9of the first cross member8and the second intermediate part14of the second cross member13are disposed in mutual opposition at a distance from each other, and are joined by the joining members20. In this case, although the first and second intermediate parts9,14which extend in the vehicle width direction, and the first and second end parts10,15which extend at an inclination, are bend or curved and connected, it is possible to reduce the bending angle at the connection part to the extent that the first and second intermediate parts9,14are mutually separated. For this reason, it is possible to suppress the deterioration in the individual strength of the first cross member8or second cross member13(materials) due to the extension with curvature at an inclination, thereby further improving the overall rigidity of the structure.

Because the bolt insertion holes28shown inFIG. 4at the rear of the joining member20have an elongated shape, it is possible to vary and adjust the distance between the end12of the first cross member8and the end17of the second cross member13in accordance with the priorly established distance L (shown inFIG. 3) between the mounting plate18at the rear of the front leg part4and the mounting plate19at the front of the rear leg part5.

That is, even if a dimensional error occurs in the first cross member8or the second cross member13at the time of fabrication, it is possible to absorb this error by a change in the distance between the first intermediate part9and the second intermediate part14. There is therefore an improvement in quality of the assembly of the first and second cross members8,13into the vehicle body. It will be understood that although in this embodiment the bolt insertion holes28of the joining members20are elongated, it is alternatively possible to elongate the bolt holes23,24provided in the first flange part21or the second flange part22of the first intermediate part9or the second intermediate part14, respectively.

Additionally, because the rack bracket33supporting the steering rack unit29for transmitting operation of the steering wheel to the left and right wheels is fixed to the extension part11of the first end part10of the first cross member8, it is possible by the rack bracket29to reduce a loss of the individual strength of the first cross member8(material) caused by the first intermediate part9and the first end part10being bent or curved and connected, thereby providing a further improvement in the rigidity of the overall structure.

In this manner, it is possible to achieve good assembly and achieve rigidity without the need for partial reinforcement, thereby enabling achievement of a suspension support structure that is both low in cost and lightweight.

Although in this embodiment the rack bracket33is fixed to the extension part11of the first end part10of the first cross member8, regardless of the position of fixing to the first cross member8, it is possible to suppress a deterioration in strength of the first cross member8. Therefore, the rack bracket33can be fixed to the first intermediate part9or to the end12, but it is preferable that it be fixed to the extension part11, which has the greatest deterioration in strength of the first cross member8.

A second embodiment of the present invention is described below, with reference to FIG.8.

A support structure according to this embodiment is the same as the first embodiment from which the joining members20have been removed. Elements that are the same as those in the first embodiment have been assigned the same reference numerals and will not be described herein.

Specifically, in this embodiment, as shown inFIG. 8, the first intermediate part9of the first cross member50and the second intermediate part14of the second cross member51are disposed so as to be adjacent at the front and rear, and the intermediate parts9,14are directly bolted together by a bolts and nuts (not shown in the drawing).

According to this embodiment, in the same manner as in the first embodiment of the present invention, because the first cross member50and the second cross member51which join and support the left and right suspension arms7have an overall shape that is substantially X-shaped, even if forces in opposite directions act on the first and second cross members50,51, the left and right first end parts10extending forward at an inclination and the left and right second end parts15extending rearward at an inclination support these forces properly. It is therefore possible, without the need for partial reinforcement, to firmly support the forces acting on the first and second cross members50,51, thereby resulting in the simplification of the structure, reduced cost, and light weight.

Because the structure, the overall shape of which substantially an X-shape, is divided into two members (the first cross member50and the second cross member51), compared to the case in which the overall structure is configured from a single member, each member is reduced in size, thereby making it possible to achieve the required dimension accuracy at the time of fabrication. It is therefore difficult for relative positional offset to occur when the first and second cross members50and51are assembled to the vehicle body, thereby achieving quality assembly.

Because the rack bracket33is fixed to the extension part11of the first end part10of the first cross member50, it is possible to reduce a loss of the individual strength of the first cross member50(material) by the rack bracket33, thereby providing a further improvement in the rigidity of the overall structure.

Additionally because in this embodiment of the present invention in particular the first cross member50and the second cross member51are directly joined, it is possible to reduce the number of parts and lighten and simplify the structure compared to the first embodiment, which requires a strut.

It is possible in this manner to achieve good assembly, achieve rigidity, and obtain a suspension support structure with low cost and light weight, without the need for partial reinforcement.

Although the first and second embodiments of the present invention are described in terms of a suspension support structure applied to a vehicle having a chassis frame, it will be understood that it is also possible to apply the present invention to a vehicle of monocoque body construction. It is further possible to join the first and second cross members8,13,50, and51directly to the side members1, without using bracket2. It is also possible to join the suspension arms7directly to the first and second cross members8,13, not to the bracket2. Additionally, it is possible to fix the rack bracket33to the second end part15of the second cross members13,51.

As described in detail above, according to the present invention it is possible without the need for partial reinforcement, to achieve a good assembly, achieve rigidity, and obtain a suspension support structure that is low-cost and lightweight.

While preferred embodiments of the present invention are described above using specific terms, such description is exemplary and will not be taken to be restrictive, and it will be understood that changes and variations may be made to the present invention within the spirit of the present invention or the scope of the present invention as recited in the accompanying claims.