JP2009234334A - Lower vehicle body structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict a rolling action of a vehicle having a rigid axle suspension mechanism assembled in a ladder frame structure. <P>SOLUTION: A main frame 110 is formed with each of openings 160 for a shock absorber for receiving the upper end of a shock absorber 150. This opening 160 is formed at the front part of a rigid axle case 120 in a right side main frame 110R and formed at the rear side of the rigid axle case 120 in a left side main frame 110L. The shock absorber 150 inserted into the opening 160 for the shock absorber has an axle member 164 inserted into its upper end eye 150a, and the axle member 164 is supported by a bearing member 166 fixed to the upper wall of the main frame 110. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vehicle body lower structure, and more particularly to a vehicle body lower structure provided with a rigid axle employed in a suspension mechanism such as a truck.

  As seen in Patent Documents 1 and 2, a truck generally has a pair of left and right main frames having a closed rectangular cross section, which extends from the front end to the rear end of the vehicle body, and between the left and right main frames. A lower structure in which a plurality of cross members are arranged at intervals in the longitudinal direction of the vehicle body, that is, a frame structure is adopted. This type of frame structure is called a “ladder frame”.

  In trucks with large changes in load capacity, the rigid axle suspension mechanism is traditionally used as the suspension mechanism for the rear wheels. As shown in FIG. 11, in the rigid axle suspension mechanism, the left and right rear wheels 2, 2 substantially integrated by the rigid axle case 1 are interlocked with each other, and the cargo box 3 rolls accordingly. The left and right rear wheel shock absorbers 4 and 4 are preferably disposed as close to the rear wheels as possible to suppress the roll. However, in the case of a ladder frame structure, assembling a shock absorber on the lateral sides of the left and right main frames 5, 5 in the vehicle width direction is an unrealistic design because the shock absorber interferes with the rear wheels. End up. For this reason, conventionally, a configuration in which the shock absorbers 4 and 4 are assembled to the inner side surfaces of the left and right main frames 5 and 5 in the vehicle width direction is employed.

  The disadvantage of the combination of the ladder frame structure and the rigid axle suspension mechanism, that is, the left and right rear wheels 2 and 2 are interlocked with each other, so that the vehicle body (the cargo box 3) is easy to roll, and this roll is suppressed. In view of the drawback that it is difficult, Patent Document 3 proposes to adopt an independent suspension instead of the rigid axle suspension and also proposes a frame structure suitable for the independent suspension.

Japanese Utility Model Publication No. 58-60571 JP-A-8-175143 Japanese Utility Model Publication No. 58-60571

  The rigid axle suspension mechanism consists of a rigid axle, a leaf spring, and a shock absorber, but the leaf spring is difficult to throw away for trucks and buses where the change in vehicle height is small even if the load changes greatly. Has advantages.

  An object of the present invention is to provide a vehicle body lower structure that can suppress a roll of a vehicle in which a rigid axle suspension mechanism is incorporated in a ladder frame structure.

According to the present invention, the above technical problem is
A vehicle body lower structure in which a rigid axle suspension mechanism for rear wheels is disposed at the rear end portions of the left and right main frames extending from the front end portion to the rear end portion of the vehicle body,
A leaf spring disposed along the lower surface of the main frame;
It is achieved by providing a vehicle body lower structure comprising a shock absorber formed by the main frame and disposed in a space which is located on the axis of the main frame and is open at least upward.

  According to the present invention, in the rigid axle suspension mechanism, the shock absorber can be arranged on the axis of the main frame in a plan view, and it is closer to the rear wheel than before without causing the problem of interference with the rear wheel. Since the shock absorber can be disposed, the roll of the vehicle can be suppressed. Further, since the space formed by the main frame is open upward, a long shock absorber can be arranged as in the conventional case.

  Typically, the “space located on the axis of the main frame” is typically “a shock absorber opening through which the space located on the axis of the main frame vertically penetrates the main frame”. Second, “a space formed by providing the main frame with a curved portion obtained by bending the main frame inward in the vehicle width direction”.

  The “space located on the axis of the main frame” is the first “shock absorber opening that penetrates the main frame vertically”, and the portion where the shock absorber opening is provided is located in the vehicle width direction. In the case where the main frame has a bulging shape or when the second “curved portion in which the main frame is bent inward in the vehicle width direction” is provided in the main frame, the space located on the axis of the main frame is Preferably, one main frame of the left and right main frames is positioned forward of the rigid axle case included in the rigid axle suspension mechanism, and the other main frame is positioned rearward of the rigid axle case.

  According to this, the fuel tank disposed in front of the rigid axle case included in the rigid axle suspension mechanism is located behind the other main frame, that is, the rigid axle case, "a space located on the axis of the main frame" A fuel tank having the same volume as that of the conventional fuel tank can be mounted.

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

The first embodiment (FIGS. 1-9):
FIG. 1 is a perspective view of a rear portion of a track related to the first embodiment as seen from the side, and FIG. 2 is a perspective view as seen from above. As is well known, the truck 100 has an engine room (not shown) and a cabin 102 (FIG. 1) in order toward the rear in the longitudinal direction of the vehicle body, and has a cargo box 104 following the cabin 102.

  As the frame structure of the track 100, a ladder frame structure is adopted as in the conventional case. That is, it has a pair of left and right main frames 110, 110 extending in the vehicle longitudinal direction from the front end portion to the rear end portion of the truck 100, and between the left and right main frames 110, 110 from the front end portion of the vehicle body. The first to fifth five cross members are sequentially arranged at intervals, and FIG. 2 shows the fourth and fifth cross members 112 and 114 located at the rear of the vehicle body.

  A rigid axle case 120 is disposed in the vicinity of the fourth cross member 112. The rigid axle case 120 incorporates a differential gear (not shown in the drawing) at the center in the vehicle width direction. As is well known, the output from the engine mounted in the engine room is transmitted to the differential gear via the propeller shaft 122 and distributed to the left and right rear wheels 124 and 124 via this differential gear. In the figure, reference numeral 130 denotes a fuel tank, 132 denotes an exhaust pipe, and 134 denotes a main silencer.

The rear wheel suspension mechanism of the track 100 includes a leaf spring 140. A front bracket 142 and a rear bracket 144 are fixed to the main frame 110 at a rear end portion of each main frame 110 so as to be separated from each other in the vehicle longitudinal direction, and a front end of a leaf spring 140 is connected to the front bracket 142. The rear end of the leaf spring 140 is connected to the rear bracket 144 via a link 146.

  The rear wheel suspension mechanism also includes left and right shock absorbers 150, and each shock absorber 150 is disposed on the axis of the main frame 110 corresponding thereto. This will be described in detail. First, the left and right main frames 110 and 110 have a rectangular closed cross-sectional structure (FIG. 4) with a frame inner 116 and a frame outer 118, and the rear portions of the left and right main frames 110 and 110 Extend parallel to each other (FIG. 2).

  2 and 3, “R” is added to the right main frame 110 and “L” is added to the left main frame 110 for identification. A shock absorber 150 is disposed on the right main frame 110R behind the rigid axle case 120 on its axis. On the other hand, a shock absorber 150 is disposed in front of the rigid axle case 120 on the left main frame 110L on its axis.

  5 and 6, the leaf spring 140 and the rigid axle case 120 are integrated by the spring seat 152, but the portion where the spring seat 152 at the left and right ends of the rigid axle case 120 is fastened, that is, A shock absorber mounting bracket 154 that pivotally supports the lower end of the shock absorber 150 is fixed to the lower portion on the axis of the main frame 110 by welding (FIG. 7). The shock absorber mounting bracket 154 extends forward at the right end of the rigid axle case 120, and extends rearward at the left end of the rigid axle case 120.

  Returning to FIG. 3, the main frame 110 has an opening 160 for receiving the upper end portion of the shock absorber 150. The shock absorber opening 160 penetrates the main frame 110 vertically (FIG. 8). A shock absorber opening 160 is formed in front of the rigid axle case 120 in the right main frame 110R. On the other hand, a shock absorber opening 160 is formed in the left main frame 110L behind the rigid axle case 120. As can be seen best from FIG. 3, the portion of each main frame 110 where the shock absorber opening 160 is formed has a shape that bulges left and right. That is, as described above, the main frame 110 includes the frame inner 116 and the frame outer 118. However, the frame inner 116 has an inner portion in the vehicle width direction with respect to the portion where the shock absorber opening 160 is provided. An inwardly bulging portion 116a having an arcuate shape in plan view that bulges toward the direction is formed, and an outwardly bulging portion having an arc shape in plan view bulging outward in the vehicle width direction is formed on the frame outer 118. 118a is formed. The shock absorber opening 160 is constituted by a pair of half cylinders 162 and 162 shown in FIG. 9 shows an example in which the half cylinders 162 and 162 are installed on the left main frame 110L, and the half cylinder 162 is attached to the left main frame 110L in a posture inclined obliquely rearward by an angle θ. Installed. On the other hand, with respect to the right main frame 110R, the half cylinder 162 is installed in an obliquely inclined posture.

  The shock absorber 150 inserted into the shock absorber opening 160 has a shaft member 164 inserted into an upper end eye 150a thereof, and the shaft member 164 is fixed to the upper wall of the main frame 110 across the shock absorber opening 160. Supported by 166.

  With the above-described configuration, each shock absorber 150 is positioned on the axis of the main frame 110 having a ladder frame structure when viewed from the top, and obliquely separated from the rigid axle case 120 with respect to the right main frame 110R when viewed from the side. It arrange | positions in the state inclined forward. On the other hand, the left shock absorber 150 is disposed obliquely rearward from the rigid axle case 120.

  As described above, since the shock absorber 150 is arranged on the axis of the main frame 110 having the ladder frame structure, there is no possibility that the shock absorber 150 interferes with the rear wheel 124, and the figure used in the description of the conventional example. 11, since the shock absorber 150 is located outside the vehicle width direction, that is, at a position closer to the rear wheel 124 (reference numeral 2 in FIG. 11) than the conventional one, Roll can be suppressed.

  Also, by inserting the upper end of the shock absorber 150 into the shock absorber opening 160 formed in the main frame 110, a relatively long shock absorber 150 can be installed, so that the shock can be reduced with a long stroke. Can do. In addition, the portion of the main frame 110 where the shock absorber opening 160 is formed bulges in an arc shape in a plan view inward and outward in the vehicle width direction by the inner and outer bulging portions 116a and 118a of the frame inner 116 and the frame outer 118. Therefore, a difference in behavior is not induced between the left and right main frames 110 in the case of a rear collision.

Second Embodiment (FIG. 10):
FIG. 10 is a view of the left and right main frames 110R and 110L of the ladder frame as viewed from above in the second embodiment. It will be understood from FIG. 10 that a part of the left and right main frames 110R and 110L is curved inward in the vehicle width direction. The curved portions 170R and 170L are offset back and forth across the rigid axle case 120. Specifically, the curved portion 170R of the right main frame 110R is located in front of the rigid axle case 120, while the left main frame 110L is located behind the rigid axle case 120.

  Thus, by providing the main frame 110 with the curved portion 170 curved inward in the vehicle width direction, the shock absorber 150 can be mounted by attaching the upper end of the shock absorber 150 to the lateral side of each main frame 110 in the vehicle width direction. It can be arranged on the axis of the main frame 110 in plan view. Reference numeral 172 indicates a shaft member that pivotally supports the upper end eye 150 a of the shock absorber 150, and the shaft member 172 extends outward in the vehicle width direction of each main frame 110.

  As in the second embodiment, the upper end portion of the shock absorber 150 is attached to the outer side surface of the main frame 110 in the vehicle width direction by providing the main frame 110 with a curved portion 170 that curves inward in the vehicle width direction. This makes it possible to install the shock absorber 150 close to the rear wheel 124 while installing a long shock absorber in the same manner as attaching to the inner side surface of the conventional main frame in the vehicle width direction.

  Further, the curved tanks 170R and 170L of the left and right main frames 110R and 110L are offset back and forth across the rigid axle case 120, so that the fuel tank 130 disposed adjacent to the front of the rigid axle case 120 is shown in FIG. As can be seen from the above, by arranging the fuel tank 130 on the side where the curved portion 170 is located behind the rigid axle case 120 (left side in the second embodiment), it is possible to mount a fuel tank having the same volume as the conventional one. it can.

It is the perspective view which looked at the track of the 1st example from the side. It is the perspective view which looked at the track of Drawing 1 from the upper part. It is the perspective view which extracted the rear part of the ladder frame structure of FIG. It is sectional drawing of a main frame. It is a fragmentary perspective view which shows the attachment structure of the leaf | plate spring fixed to a rigid axle case, and a shock absorber. FIG. 6 is a cross-sectional view related to FIG. 5. It is a fragmentary perspective view for demonstrating the bracket of the rigid axle case for attaching the lower end part of a shock absorber. It is sectional drawing along the VIII-VIII line of FIG. It is a perspective view for demonstrating the half cylinder for forming the opening for shock absorbers in the rear-end part of a main frame. It is the figure which looked at the rear part of the ladder frame structure regarding 2nd Example from the bottom. It is a figure for demonstrating the conventional structure and its problem.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Truck 104 Cargo box 110 Main frame 116 Frame inner 116a Inward bulging part of frame inner 118 Frame outer 118a Outer bulging part of frame outer 120 Rigid axle case 122 Propeller shaft 124 Rear wheel 130 Fuel tank 140 Leaf spring 150 Shock Absorber 150a Top eye 152 Spring seat 154 Shock absorber mounting bracket 160 Shock absorber opening

Claims (5)

A vehicle body lower structure in which a rigid axle suspension mechanism for rear wheels is disposed at the rear end portions of the left and right main frames extending from the front end portion to the rear end portion of the vehicle body,
A leaf spring disposed along the lower surface of the main frame;
A vehicle body lower structure, comprising: a shock absorber disposed in a space formed by the main frame and located on an axis of the main frame and open at least upward. The space located on the axis of the main frame is a shock absorber opening that vertically penetrates the main frame,
The vehicle body lower part structure according to claim 1, wherein an upper end portion of the shock absorber is inserted into the shock absorber opening.   The vehicle body lower part structure according to claim 2, wherein a portion of the main frame in which the shock absorber opening is provided has a shape bulging inward and outward in the vehicle width direction. A space located on the axis of the main frame is formed by providing the main frame with a curved portion that curves the main frame inward in the vehicle width direction.
The vehicle body lower part structure according to claim 1, wherein an upper end portion of the shock absorber is attached to an outer side surface in the vehicle width direction of the curved portion of the main frame.   The space located on the axis of the main frame is located in front of the rigid axle case included in the rigid axle suspension mechanism in one main frame of the left and right main frames, and in the other main frame than the rigid axle case. The vehicle body lower part structure according to claim 3 or 4, which is located rearward.

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