JP2005186898A - Suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the fatigue strength at a joining part of each side rail and a cross member without increasing the weight of a vehicle. <P>SOLUTION: In a suspension device in which an axle 3 is suspended by a vehicle body side via an air spring 11, the air spring 11 is disposed on the inner side of the vehicle width direction of right and left side rails 1, a top part of the air spring 11 is fixed by a cross member 13 stretched between the side rails 1, and the cross member 13 is formed of a leaf spring material identical to that of a leaf spring 2 (or a material similar thereto: alloy steel with toughness). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a suspension device.

  There are various types of suspensions that are used to suspend the vehicle axle on the side rails. Among them, the leaf suspension, which consists of multiple leaf springs, has a simple structure. It has the features of low cost, high strength and high durability, and has been widely used in vehicles such as trucks.

  However, the conventional leaf suspension cannot be denied that its riding comfort is inferior to that of the current air suspension, and the combined use of leaf springs and air springs reduces riding costs while reducing costs. Research and development of suspension devices that can be improved is underway.

  3 to 5 show an example of a conventional suspension device using both a leaf spring and an air spring. In FIG. 3, reference numeral 1 denotes a pair of left and right side rails extending in the vehicle front-rear direction and forming a part of a chassis frame. Is a leaf spring installed along the side rail 1 in the longitudinal direction of the vehicle, 3 is an axle extending in the vehicle width direction, and the axle 3 is U-bolt 4 with respect to the upper surface of the longitudinal middle portion of the leaf spring 2. Are connected through.

  In the example shown here, the front half of the leaf spring 2 has a two-layer structure, and the front end of the leaf spring 2 is wound upward to form an eye 2a. Wrapped around the horizontal pin 6 mounted on the bracket 5 so as to be freely tiltable (note that the break position of the leaf spring 2 in FIG. 4 is shifted forward from the arrow IV-IV for convenience of explanation). ing).

  On the other hand, the rear end portion of the leaf spring 2 is wound upward in the same manner as the front end portion, and is formed as an eye 2b. The eye 2b is a horizontal pin of the shackle 8 mounted on the rear bracket 7 on the side rail 1 side. 9, the leaf spring 2 is bent in an arcuate shape so that the expansion and contraction in the front-rear direction caused by the bow spring is absorbed by the swinging of the shackle 8.

  In addition, a support beam 10 extending inward in the vehicle width direction is also coupled with the U-bolt 4 at a place where the axle 3 is supported by the leaf spring 2 via the U-bolt 4. An air spring 11 is seated on a portion of the beam 10 that protrudes inward in the vehicle width direction with respect to each side rail 1, and the top of each air spring 11 is fixed by a cross member 12 installed between the side rails 1. Yes.

  That is, when the layout in which each air spring 11 is offset to the position shifted inward in the vehicle width direction from directly below the left and right side rails 1 is employed, the air springs 11 are not interfered with the leaf springs 2 and sufficient. It is possible to arrange them with a height (capacity) (see FIG. 3).

  In addition, as far as the applicant of the present application knows, there are very few domestic examples of offset arrangement of the air spring 11 of this type in the vehicle width direction. Have already filed Japanese Patent Application Nos. 2002-263998 and 2003-164740, which have not been disclosed, as prior art relating to a suspension device using both leaf springs and air springs.

  However, the conventional suspension apparatus described above with reference to FIGS. 3 to 5 has a U-shaped cross section for fixing the top of the air spring 11 disposed on the inner side in the vehicle width direction with respect to the left and right side rails 1. Since the cross member 12 having high rigidity is used to support a large load in the vertical direction of the vehicle, the cross member 12 having such high rigidity is heavy and results in an increase in the vehicle weight. In addition, when rolling occurs in the vehicle body due to cornering or the like, if each side rail 1 is twisted, particularly high stress is generated at the joint between each side rail 1 and the cross member 12, and fatigue strength is reduced. There was a problem to do.

  It should be noted that increasing the fatigue strength of the joint portion between each side rail 1 and the cross member 12 by reinforcement results in a further increase in the vehicle weight, resulting in a further increase in weight. No countermeasure is desired.

  The present invention has been made in view of the above circumstances, and an object thereof is to improve the fatigue strength at the joint portion between each side rail and the cross member without causing an increase in vehicle weight.

  The present invention relates to a suspension device in which an axle is suspended on the vehicle body side via an air spring. An air spring is disposed on the inner side in the vehicle width direction with respect to the left and right side rails, and the top portion of the air spring is disposed between the side rails. The cross member is fixed by a cross member laid on, and the cross member is made of alloy steel having toughness.

  Thus, in this way, the air springs are arranged on the inner side in the vehicle width direction than the left and right side rails, so that each air spring has a sufficient height (capacity) and a low spring constant (multiplier). This is an alloy steel that has a tough cross member for fixing the top of the air spring even when such an offset arrangement of the air spring in the vehicle width direction is adopted. Therefore, when the side rails are twisted, the cross member side is flexibly deformed, and high stress is hardly generated at the joint portion of the cross member.

  In addition, if the cross member is made of tough alloy steel, yield / fatigue strength several times that of materials used for general vehicle frames can be obtained. Even if it is not a cross member with a large total area, a flat cross member with a small total area can sufficiently support a large load in the vertical direction of the vehicle, and the weight of the cross member can be greatly reduced. It becomes possible.

  Furthermore, when carrying out the present invention more specifically, for example, it is preferable to apply heat treatment to the alloy steel forming the cross member to impart toughness or to perform shot peening.

  According to the suspension device of the present invention described above, even if the side rails are twisted, the cross member side can be flexibly deformed so that no high stress is generated in the joint portion. A flat cross member with a small area can sufficiently support a large load in the vertical direction of the vehicle and can greatly reduce the weight of the cross member. An excellent effect that the fatigue strength can be improved without increasing the vehicle weight can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 and FIG. 2 show an example of an embodiment for carrying out the present invention, and portions denoted by the same reference numerals as those in FIGS. 3 to 5 represent the same items.

  As shown in FIGS. 1 and 2, in this embodiment, an air spring 11 is arranged on the inner side in the vehicle width direction from the left and right side rails 1 in the same manner as in FIGS. The suspension device has a top portion fixed by a cross member 13 laid between the side rails 1. The cross member 13 is a leaf spring material similar to the leaf spring 2 (or its approximate material: an alloy having toughness). Steel).

  This type of leaf spring material is subjected to heat treatment such as quenching and tempering to impart toughness, but it is preferable to further increase the fatigue strength by subjecting it to shot peening.

  That is, if a residual stress is applied by hitting a shot (small steel ball) at a high speed on the surface of the leaf spring material forming the cross member 13, the fatigue strength of the cross member 13 is improved.

  In the example shown here, a pair of cross members 13 formed in a flat plate shape are laid between the side rails 1 in parallel, and air springs 11 are formed on the lower surfaces of the cross members 13. The top is fixed by bolt fastening or the like.

  Thus, by arranging the air springs 11 on the inner side in the vehicle width direction from the left and right side rails 1 in this way, each air spring 11 has a sufficient height (capacity) and a low spring constant. The cross member 13 for fixing the top portion of the air spring 11 can be achieved even if such an offset arrangement of the air spring 11 on the inner side in the vehicle width direction is employed. Is made of a leaf spring material, when each side rail 1 is twisted, the cross member 13 side is flexibly deformed, and high stress is hardly generated at the joint portion of the cross member 13.

  Further, if the cross member 13 is made of a leaf spring material, yield / fatigue strength several times that of a material used for a general vehicle frame can be obtained. Even if the cross member 12 having a large area (see FIGS. 3 to 5) is not used, the flat cross member 13 that requires a small total area can sufficiently support a large load in the vehicle vertical direction. Thus, the weight can be significantly reduced by 13.

  Therefore, according to the above embodiment, even if the side rails 1 are twisted, the cross member 13 side can be flexibly deformed so that no high stress is generated in the joint portion. Since the flat cross member 13 having a small area can sufficiently support a large load in the vertical direction of the vehicle and the weight of the cross member 13 can be significantly reduced, each side rail 1, cross member 13, The fatigue strength at the joint can be improved without increasing the vehicle weight.

  The suspension device of the present invention is not limited to the above-described embodiment. The cross member does not necessarily have to be made of a leaf spring material, and an alloy steel having toughness such as an approximate material of the leaf spring material. Of course, incidental equipment such as leaf springs that are appropriately used together is not limited to the structure shown in the drawing, and various modifications can be made without departing from the scope of the present invention. is there.

It is a front view which shows an example of the form which implements this invention. It is an arrow view of the II-II direction of FIG. It is a side view which shows a prior art example. FIG. 4 is an arrow view in the IV-IV direction of FIG. 3. FIG. 5 is an arrow view in the VV direction of FIG. 4.

Explanation of symbols

1 Side rail 3 Axle 11 Air spring 13 Cross member

Claims (3)

  In a suspension device in which the axle is suspended on the vehicle body side via an air spring, an air spring is arranged on the inner side in the vehicle width direction than the left and right side rails, and the top of the air spring is installed between the side rails. A suspension device characterized in that it is fixed by a member and the cross member is made of tough alloy steel.   The suspension apparatus according to claim 1, wherein the alloy steel forming the cross member is heat-treated to give toughness.   2. The suspension apparatus according to claim 1, wherein the alloy steel forming the cross member is shot peened.

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