JP2009292376A - Suspension device and its under-steer suppression method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance operation stability of a vehicle in addition to relaxation of impact against push-up input from a road surface and stroke restriction as the function of a bumper rubber. <P>SOLUTION: A rear axle 3 is mounted to an upper part of a leaf spring 5 through an axle housing 19. The axle housing 19 is provided with front and rear bumper rubber receiving parts 23 and 25 projected in a vehicle longitudinal direction respectively, and above the front and rear bumper rubber receiving parts 23 and 25, front and rear bumper rubber 35 and 37 suspended from a rear side member are provided respectively. The rear bumper rubber 37 is downwardly projected more than the front bumper rubber 35, and a clearance dimension between the rear bumper rubber 37 and the rear bumper rubber receiving part 25 is made shorter than a clearance dimension between the front bumper rubber 35 and the front bumper rubber receiving part 23. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a suspension device for supporting an axle on a vehicle body via a leaf spring and a method for suppressing understeer thereof.

The longitudinal center of the leaf spring along the longitudinal direction of the vehicle is connected to the axle via the axle housing, and the axle housing is provided with front and rear bumper bar receiving portions that project in the longitudinal direction of the vehicle. There is known a suspension apparatus in which a bumper bar serving as an impact absorbing member facing the part is provided on the vehicle body side (see Patent Document 1 below).
Japanese Utility Model Publication No. 62-148408

  By the way, the function of the bumper bar in the above-described suspension device is to mitigate the impact against the thrust input from the road surface and to restrict the stroke, but does not particularly take into consideration the improvement of the steering stability of the vehicle.

  For example, in consideration of handling stability, it is common to set the understeer to a weaker understeer by increasing the understeer when loading a baggage rather than when the baggage is not loaded. In such a setting, there may be an oversteer when the vehicle is unloaded, which may suppress an improvement in steering stability.

  Contrary to the above, if the understeer is strengthened and set to weak understeer at the time of empty load, the understeer becomes stronger and strong understeer at the time of cargo loading, and also in this case, there is a risk of suppressing improvement in steering stability.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the steering stability of a vehicle while maintaining the functions of a shock absorbing member from a road surface and a function of reducing a stroke and a stroke restriction as a function of an impact absorbing member.

  In the present invention, the axle mounting member for connecting the leaf spring to the axle has a front projecting portion and a rear projecting portion that project in the vehicle front-rear direction with respect to the axle, and in the vertical direction between the front projecting portion and the vehicle body. A front impact absorbing member is provided in at least one of the mutually facing parts, and a rear impact absorbing member is provided in at least one of the parts facing each other in the vertical direction of the rear protrusion and the vehicle body so that the axle approaches the vehicle body. When the leaf spring is bent and deformed and at least one of the front impact absorbing member and the rear impact absorbing member abuts against the opposing portion and a load is applied, the axle mounting member is attached to the leaf spring. And the axle moves to the rear of the vehicle with respect to the vehicle body.

  According to the present invention, when the leaf spring is bent and deformed so that the axle approaches the vehicle body, when the at least one of the front impact absorbing member and the rear impact absorbing member comes into contact with the facing portion, the axle mounting member is Since the axle moves with the leaf spring mounting part as a fulcrum and the axle moves to the rear of the vehicle, the axle that has moved to the rear of the vehicle corresponds to the outer rear wheel when the vehicle turns on a curved road. The action of moving the front part of the vehicle toward the inside in the turning direction by the amount of the movement is changed by the left and right rear wheels in a direction in which oversteer becomes stronger, and understeer is suppressed.

  For this reason, in consideration of handling stability, even when the understeer is not loaded and the understeer is strengthened and set to weak understeer, the leaf spring bends so that the axle as described above approaches the vehicle body. When loading a load, which corresponds to the case of deformation, the oversteer changes in a direction in which it becomes stronger than when empty. As a result, it is possible to suppress the understeer at the time of loading from becoming excessively stronger than at the time of empty loading, and it is possible to secure the optimum weak understeer at the time of empty loading and loading to improve the steering stability.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view of a suspension device showing a first embodiment of the present invention, and FIG. 2A is a side view of the suspension device. The direction indicated by the arrow FR in the figure is the front of the vehicle, the direction indicated by the arrow LH is the left side of the vehicle, and the suspension device of FIG. 1 is viewing the rear suspension device on the left side of the rear of the vehicle from the front side of the vehicle body. The rear suspension device on the right side of the rear part of the vehicle has a structure symmetrical to that of FIG.

  A rear axle 3 as an axle that is a drive shaft extending in the vehicle width direction is disposed below a rear side member 1 that is a vehicle body skeleton member that extends in the vehicle longitudinal direction and constitutes a vehicle body. A wheel (not shown) is attached to the portion 3a.

  A leaf spring 5 extending in the vehicle front-rear direction is disposed below the rear side member 1. The leaf spring 5 is curved so that both sides in the vehicle front-rear direction are directed upward, and a front end portion thereof can be rotated via a rotation support pin 9 to a front bracket 7 depending from the rear side member 1. Support.

  On the other hand, the rear end portion of the leaf spring 5 is connected to a rear bracket 11 suspended from the rear side member 1 via an upper rotation support pin 13 so as to be pivotable. The end is supported so as to be rotatable via a lower rotation support pin 17.

  The central portion of the leaf spring 5 in the longitudinal direction (vehicle longitudinal direction) is connected to the rear axle 3 via an axle housing 19 as an axle mounting member. The axle housing 19 includes a boss portion 21 provided with a support hole 21 a into which the rear axle 3 is inserted, a front bumper bar receiving portion 23 as a front protruding portion protruding from the boss portion 21 toward the front of the vehicle, and the boss portion 21. A rear bumper bar receiving portion 25 as a rear protruding portion that protrudes toward the rear of the vehicle, and a fixing portion 27 that is fixed in close contact with the upper surface of the leaf spring 5 are provided.

  Then, the leaf spring 5 is clamped and fixed by the fixing portion 27 and the fixing plate 29 disposed on the lower side of the leaf spring 5 with respect to the fixing portion 27, and the bolt 31 and the nut 33 are fastened in the clamped state. By fixing, the axle housing 19 is fixed to the leaf spring 5.

  The front and rear bumper bar receiving portions 23 and 25 of the axle housing 19 have planar front and rear bumper bar receiving surfaces 23a and 25a, respectively, on the upper surface of the rear side member 1 located above. A front bumper bar 35 as a front shock absorbing member and a rear bumper bar 37 as a rear shock absorbing member are provided below the rear side member 1 at positions facing the bumper bar receiving surfaces 23a and 25a in the vertical direction. The front bumper bar 35 and the rear bumper bar 37 are respectively fixed to the lower surfaces of rubber mounting blocks 39 and 41 attached to the lower surface of the rear side member 1, and the tip (lower end) has a convex arc shape.

  Further, as shown in FIG. 2A, the front and rear bumper bar receiving portions 23 and 25 are leaf springs having a shape in which the distal end side is thin and the proximal end side on the boss portion 21 side is thick with respect to the thickness in the vertical direction. 5 is an inclined surface, and the distance 43 from the leaf spring 5 is increased toward the tip side.

  In this example, the rear bumper bar 37 is made longer and longer than the front bumper bar 35 so that the gap A between the rear bumper bar 37 and the rear bumper bar receiving surface 25a is set to the front bumper bar 35. It is set shorter than the gap dimension B between the front bumper bar receiving surface 23a.

  That is, the gap dimension between the rear shock absorbing member and the part facing the rear shock absorbing member in the vertical direction is the gap dimension between the front shock absorbing member and the part facing the front shock absorbing member in the vertical direction. It will be shorter.

  In addition, in the state of Fig.2 (a), the front bumper bar receiving surface 23a and the back bumper bar receiving surface 25a shall be located on the substantially the same horizontal surface.

  According to the suspension device of the present embodiment described above, when the leaf spring 5 is bent and deformed from the state of FIG. 2A so that the rear axle 3 approaches the rear side member 1 on the vehicle body side, as shown in FIG. In addition, in a state where the front bumper bar 35 is not in contact with the front bumper bar receiving surface 23a, in other words, the rear bumper bar 37 contacts the rear bumper bar receiving surface 25a before the front bumper bar 35 contacts the front bumper bar receiving surface 23a. Elastically deforms in contact.

  As a result, the axle housing 19 is watched together with the rear axle 3 in FIG. 2 (b) with the vicinity of the clamping portion of the leaf spring 5 by the fixing portion 27 and the fixing plate 29 as the attachment site to the leaf spring 5 as a fulcrum. For example, the angle θ is turned in the direction, and the rear axle 3 moves from the state shown in FIG.

  Here, the rear axle 3 moving to the rear of the vehicle turns on the bounce side where the center portion of the leaf spring 5 is displaced upward and the vehicle body is bent toward the road surface when the vehicle turns on a curved road. Assume that it is located outside. In this case, the rear axle 3 moves rearward so that the positional relationship between the left and right rear wheels changes back and forth, and the action of moving the rear part of the vehicle toward the outside of the turn works by this change. Along with this, the action of trying to turn the front part of the vehicle toward the inside of the turn occurs, and the oversteer changes in a stronger direction.

  For this reason, in consideration of handling stability, the rear axle 3 approaches the rear side member 1 as described above even if the understeer is strengthened and set to weak understeer when no load is loaded on the vehicle. When loading a load, which corresponds to the case where the leaf spring 5 is bent and deformed, the oversteer changes in a direction in which the oversteer becomes stronger than when the load is unloaded, so that the understeer at the time of loading becomes too stronger than when unloaded. It is possible to suppress this, and it is possible to secure the optimum weak understeer at the time of empty loading and loading and improve the steering stability.

  As shown in FIG. 2B, after the rear bumper bar 37 abuts against the rear bumper bar receiving surface 25a and is elastically deformed, and the leaf spring 5 is further bent and deformed, the front bumper bar 35 comes into contact with the front bumper bar receiving surface 23a. The bumper bars 35 and 37 share the load for restricting the stroke.

  In addition, even when the rear bumper bar 37 is already in contact with the rear bumper bar receiving surface 25a at the time of loading, the outer rear wheel when traveling on a curved road is shown in FIG. The pressing load on the rear bumper bar receiving surface 25a of the rear bumper bar 37 having a short gap is larger than the pressing load of the front bumper bar 35 on the front bumper bar receiving surface 23a. For this reason, the axle housing 19 rotates in the same manner as in FIG. 2B, and the rear axle 3 moves to the rear of the vehicle, so that the oversteer becomes stronger.

  Further, when the cargo is loaded, the rear bumper bar 37 is already in contact with the rear bumper bar receiving surface 25a, and the front bumper bar 35 is also in contact with the front bumper bar receiving surface 23a. Rotates, the rear axle 3 moves rearward of the vehicle, and the direction of the oversteer changes.

  FIG. 3 shows a conventional apparatus (curve P) and the present embodiment as a view of the movement trajectory in the vehicle longitudinal direction of the axle (rear axle 3) with respect to the vertical stroke (mm) of the suspension (leaf spring 5) as seen from the side of the vehicle body. (Curve Q) is shown in comparison, and the horizontal axis is the vehicle longitudinal movement amount (mm) of the axle, that is, roll steer. In FIG. 3, the left side is the front of the vehicle.

  In the present embodiment, the position of the rear axle 3 located on the outside of the turn that becomes the bound side when the vehicle is turning is from the point Pb on the curve P to the point Qb on the curve Q of the conventional apparatus by the length L. Has moved to.

  In addition, the point R in the figure is a vehicle front-rear direction position of the rear axle that is located on the inside of the turn that becomes the rebound side during turning, and this position is deformed in a direction in which the leaf spring 5 is separated from the rear side member 1 by rebound, Since the rear bumper bar 37 is not in contact with the rear bumper bar receiving surface 25a, the force for rotating the axle housing 19 as described above is not generated, and therefore, the conventional device and the present embodiment device match.

  Further, a point S in the figure is a point where the rear bumper bar 37 starts to contact the rear bumper bar receiving surface 25a, and a point T is a point where the front bumper bar 35 starts to contact the front bumper bar receiving surface 23a. Further, the point U corresponds to an empty load when no load is loaded on the vehicle, and the point V corresponds to a load when a specified amount of load is loaded on the vehicle.

  Further, in the present embodiment, the gap dimension between the front bumper bar 35 and the front bumper bar receiving surface 23a that is a part facing the front bumper bar 35, and the rear bumper bar 37 and the rear bumper bar 37 that is a part facing the rear bumper bar 37 are provided. The gap dimension between the receiving surface 25a and the receiving surface 25a is different from each other. At this time, here, the rear bumper bar 37 on the side with the shorter gap dimension is first brought into contact with the opposite rear bumper bar receiving surface 25a, and the axle housing 19 is rotated with the attachment portion with the leaf spring 5 as a fulcrum. The axle 3 can be moved rearward of the vehicle.

  Further, in the present embodiment, when the axle housing 19 rotates around the attachment portion with the leaf spring 5 to move the rear axle 3 toward the rear of the vehicle, the rear axle 3 is moved together with the axle housing 19 to the upper part of the leaf spring 5. Is provided on the rear side member 1 side. As a result, the space between the leaf spring 5 and the rear side member 1 is effectively used, and the space between the vehicle body including these members and the road surface is kept wider than when these are provided below the leaf spring 5. be able to.

  In the present embodiment, when the gap dimension A between the rear bumper bar 37 and the rear bumper bar receiving surface 25a is set shorter than the gap dimension B between the front bumper bar 35 and the front bumper bar receiving surface 23a, the rear bumper bar 37 is set. Is made longer than the vertical length of the front bumper bar 35. Thereby, it is only necessary to change the size of the bumper bar, and there is no particular change site in the structural part on the vehicle body side, so that an increase in manufacturing cost due to the vehicle body structure change can be suppressed.

  In the above-described embodiment, the front bumper bar 35 and the rear bumper bar 37 are attached to the rear side member 1 on the vehicle body side. However, the front bumper bar and the rear bumper bar may be provided on the axle housing 19 side. A front bumper bar receiving surface and a rear bumper bar receiving surface with which the front bumper bar and the rear bumper bar abut are provided on the rear side member 1 side.

  In addition, a front bumper bar and a rear bumper bar may be provided on both the axle housing 19 side and the rear side member 1 side. In this case, the front bumper bar and the rear bumper bar also serve as the front bumper bar receiving surface and the rear bumper bar receiving surface, respectively. Will do.

  In the above-described first embodiment, the overslang structure is described in which the rear axle 3 is disposed above the leaf spring 5. However, as the second embodiment, the rear axle 3 is disposed below the leaf spring 5. The present invention can also be applied to the underslang structure.

  In the underslang structure, contrary to the above-described embodiment (overslang structure), the gap dimension between the front bumper bar 35 and the front bumper bar receiving surface 23a is the same as the gap between the rear bumper bar 37 and the rear bumper bar receiving surface 25a. Set shorter than the dimension. That is, according to the suspension device in this case, when the leaf spring 5 is bent and deformed so that the rear axle 3 approaches the rear side member 1 on the vehicle body side, the rear bumper bar is moved forward before the rear bumper bar contacts the rear bumper bar receiving surface. The bumper bar contacts the front bumper bar receiving surface.

  As a result, the axle housing rotates counterclockwise in FIG. 2B with the vicinity of the attachment site with the leaf spring 5 as a fulcrum, and the rear axle located at the lower part of the leaf spring 5 moves rearward of the vehicle accordingly. As a result of the movement, the oversteer changes in the same direction as described above, and understeer is suppressed.

  Further, in the first and second embodiments described above, the hardness of the front bumper bar 35 and the rear bumper bar 37 are equal to each other, and the rear bumper bar 37 and the rear bumper bar receiving surface 25a which is a part facing the rear bumper bar 37 are provided. The gap dimension between the front bumper bar 35 and the front bumper bar receiving surface 23a, which is the part facing the front bumper bar 35, are different from each other.

  On the other hand, the gap dimension between the front bumper bar 35 and the front bumper bar receiving surface 23a which is a part facing the front bumper bar 35, the rear bumper bar 37 and the rear bumper bar receiving surface 25a which is a part facing the rear bumper bar 37, The hardness of the front bumper bar 35 and the rear bumper bar 37 may be made different from each other by making the front bumper bar 35 and the rear bumper bar 37 different from each other.

  In this case, first, an overslang structure in which the rear axle 3 is disposed above the leaf spring 5 as in the first embodiment shown in FIG. In the third embodiment, the rear bumper bar 37 is made harder than the front bumper bar 35 to reduce the shock absorbing ability.

  As a result, when the leaf spring 5 is bent and deformed so that the rear axle 3 approaches the rear side member 1 on the vehicle body side, the front bumper bar 35 and the rear bumper bar 37 almost simultaneously correspond to the corresponding front bumper bar receiving surface 23a and rear bumper bar receiving surface 25a. And contact each.

  At this time, the pressing load of the hard rear bumper bar 37 on the rear bumper bar receiving surface 25a is larger than the pressing load of the soft front bumper bar 35 on the front bumper bar receiving surface 23a. For this reason, due to the large pressing load by the rear bumper bar 37, the axle housing 19 is moved to the leaf spring 5 by the fixing portion 27 and the fixing plate 29, which are attachment portions to the leaf spring 5, as in the first embodiment. 2 is rotated in the clockwise direction in FIG. As a result, the rear axle 3 moves from the state shown in FIG. 2A toward the rear of the vehicle, so that understeer can be suppressed as in the first embodiment.

  Next, when the materials of the front bumper bar 35 and the rear bumper bar 37 are made different from each other, for example, the rear axle is attached to the leaf spring 5 as in the second embodiment. Consider the underslang structure placed below In the fourth embodiment, contrary to the third embodiment, the front bumper bar 35 is made harder than the rear bumper bar 37 to reduce the shock absorbing ability.

  As a result, when the leaf spring 5 is bent and deformed so that the rear axle 3 approaches the rear side member 1 on the vehicle body side, the front bumper bar 35 and the rear bumper bar 37 correspond to the corresponding front bumper bar almost simultaneously, as in the third embodiment. It contacts the receiving surface 23a and the rear bumper bar receiving surface 25a.

  At this time, the pressing load applied to the front bumper bar receiving surface 23a by the hard front bumper bar 35 is larger than the pressing load applied to the rear bumper bar receiving surface 25a of the soft rear bumper bar 37. For this reason, due to the large pressing load by the front bumper bar 35, the axle housing 19 is moved to the leaf spring 5 by the fixing portion 27 and the fixing plate 29, which are attachment portions to the leaf spring 5, as in the second embodiment. 2 is rotated in the counterclockwise direction in FIG. As a result, the rear axle 3 moves from the state of FIG. 2A to the rear of the vehicle, so that understeer can be suppressed in the same manner as in the second embodiment.

1 is a perspective view of a suspension device showing an embodiment of the present invention. (A) is a side view of the suspension device of FIG. 1, and (b) is an operation explanatory view showing a state in which the rear bumper bar is in contact with the rear bumper bar receiving surface from the state of (a). FIG. 6 is an axle movement locus diagram showing a movement locus in the vehicle longitudinal direction of an axle with respect to a vertical stroke of a suspension as viewed from the side of a vehicle body in comparison with the conventional device and the present embodiment.

Explanation of symbols

1 Rear side member (vehicle body)
3 Rear axle (axle)
5 Leaf spring 19 Axle housing (axle mounting member)
23 Front bumper bar receiving part (front protruding part)
25 Rear bumper bar receiving part (rear protruding part)
35 Front bumper bar (front shock absorbing member)
37 Rear bumper bar (rear impact absorbing member)
A Dimension of gap between rear bumper bar and rear bumper bar receiving surface B Dimension of gap between front bumper bar and front bumper bar receiving surface

Claims (11)

  Both ends of the leaf spring in the vehicle front-rear direction are attached to the vehicle body, and the vehicle spring front-rear direction center portion of the leaf spring is connected to the axle via an axle attachment member, and the axle attachment member protrudes forward of the vehicle with respect to the axle. A front projecting portion and a rear projecting portion projecting rearward of the vehicle, and providing a front impact absorbing member at at least one of the front projecting portion and the vehicle body facing each other in the vertical direction, A rear impact absorbing member is provided in at least one of the portions of the rear projecting portion and the vehicle body facing each other in the vertical direction, and the leaf spring is bent and deformed so that the axle approaches the vehicle body. At least one of the member and the rear impact absorbing member abuts against the facing portion and a load is applied, and the axle mounting portion Suspension apparatus characterized by but rotates as a fulcrum mounting portion of the leaf spring with the axle, the axle is moved toward the rear of the vehicle.   The gap size between the front shock absorbing member and the portion facing the front shock absorbing member is different from the gap size between the rear shock absorbing member and the portion facing the rear shock absorbing member. The suspension device according to claim 1.   The suspension device according to claim 1, wherein the hardness of the front shock absorbing member and the hardness of the rear shock absorbing member are different from each other.   The axle is attached to the vehicle body side of the leaf spring together with the axle attachment member, and at least the rear impact absorbing member is brought into contact with the facing portion and a load is applied, and the axle attachment member is attached to the leaf spring together with the axle. The suspension device according to any one of claims 1 to 3, wherein the suspension device rotates about an attachment portion as a fulcrum, and the axle moves rearward with respect to a vehicle body.   The gap dimension between the rear shock absorbing member and the part facing the rear shock absorbing member in the vertical direction, and the gap dimension between the front shock absorbing member and the part facing the front shock absorbing member in the vertical direction The suspension device according to claim 4, wherein the suspension device is shorter.   The suspension device according to claim 4, wherein the hardness of the rear shock absorbing member is higher than the hardness of the front shock absorbing member.   The axle is mounted on the opposite side of the leaf spring from the vehicle body together with the axle mounting member, and at least the front impact absorbing member is brought into contact with the opposite portion to be loaded, and the axle mounting member is moved together with the axle to the leaf spring. The suspension device according to any one of claims 1 to 3, wherein the suspension device is rotated with a mounting portion as a fulcrum, and the axle moves rearward with respect to the vehicle body.   The gap dimension between the front shock absorbing member and the part facing the front shock absorbing member in the vertical direction, and the gap dimension between the rear shock absorbing member and the part facing the rear shock absorbing member in the vertical direction. The suspension device according to claim 7, wherein the suspension device is shorter.   The suspension device according to claim 7, wherein the hardness of the front shock absorbing member is higher than the hardness of the rear shock absorbing member.   By making the vertical length of the front shock absorbing member different from the vertical length of the rear shock absorbing member, between the front shock absorbing member and the portion facing the front shock absorbing member in the vertical direction. The suspension apparatus according to claim 2, wherein a gap dimension and a gap dimension between the rear impact absorbing member and a portion facing the rear impact absorbing member in the vertical direction are different from each other.   Both ends of the leaf spring in the vehicle front-rear direction are attached to the vehicle body, and the vehicle spring front-rear direction center portion of the leaf spring is connected to the axle via an axle attachment member, and the axle attachment member projects forward of the vehicle with respect to the axle. A front projecting portion and a rear projecting portion projecting rearward of the vehicle, and providing a front impact absorbing member at at least one of the front projecting portion and the vehicle body facing each other in the vertical direction, A rear impact absorbing member is provided in at least one of the portions of the rear projecting portion and the vehicle body facing each other in the vertical direction, and the leaf spring is bent and deformed so that the axle approaches the vehicle body. A load is applied by bringing at least one of the member and the rear impact absorbing member into contact with the opposing portion, and the axle And the member is rotated as a fulcrum mounting portion of the leaf spring with the axle, the understeer suppression method of the suspension device, characterized in that moving the vehicle backwards the axle relative to the vehicle body.

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