JPH0261669B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to FRP used in vehicle suspension systems, etc.
This invention relates to a leaf spring device.

Spring plates made of FRP (fiber-reinforced synthetic resin) are lightweight, but have lower hardness than steel springs. As a result, this portion, which is located at a location where the surface pressure is locally high, is dented, and the reinforcing fibers directly below the portion are cut, the resin is damaged, and the life of the spring plate is shortened.

FIG. 1 shows an example of an axle mounting portion of a conventional spring device. In the figure, 1 is a spring plate, 2 is an axle housing, and this axle housing 2 includes a pad 3, U bolts 4, 4, nuts 5,
5 or the like is used to restrain the spring plate 1. However, in this case, as shown by hatching in the surface pressure distribution diagram illustrated in the lower half of FIG. 1, high stress is generated near the pads, the axle housing, and the like. This kind of surface pressure distribution poses almost no practical problem in the case of conventional steel springs, but in the case of FRP spring plates, the FRP can be damaged in areas where the surface pressure is locally high as described above. Research conducted by the present inventors has revealed that the durability may not be maintained due to the exposure.

The present invention has been made based on the above circumstances, and its purpose is to disperse surface pressure on the clamping surface of a spring plate that is strongly clamped between a pair of upper and lower clamping members by a U-bolt. The purpose is to improve the durability of FRP spring plates.

The gist of the present invention is to provide an FRP leaf spring device that includes a spring plate made of FRP and a tightening structure that tightens the spring plate in the thickness direction between a pair of upper and lower tightening members using U bolts. A caul plate that is in contact with the spring plate is interposed between the clamping surface of the spring plate and the opposite clamping surface of the spring plate, and the U-bolt is provided on the caulking plate. It has an extension part that extends from the position to the end side of the spring plate, and this extension part is also in contact with the spring plate, and the extension part has a thickness that extends toward the end side of the backing plate. The reason is that the rigidity of the plate end side is gradually reduced by forming a tapered shape such that the stiffness gradually decreases.

According to the present invention having the above configuration, the rigidity of the end of the backing plate interposed on the tightening surface becomes lower toward the end of the plate, and the surface pressure gradually decreases accordingly, so that, for example, near the pad, etc. Surface pressure can be distributed around the tightening surface. Therefore, even if the spring plate is made of FRP, problems such as damage to the resin or cutting of reinforcing fibers can be prevented, and the durability of the FRP spring plate can be improved.

An embodiment of the present invention will be described below with reference to FIGS. 2 to 5. In FIG. 2, the master spring plate 10 and the slave spring plate 11 are both made of FRP, and metal eyepiece members 12, 12 are attached to both ends of the master spring plate 10. Further, protection plates 13, 13 are attached to both ends of the child spring plate 11, and protection plates 14, 14 are also provided on the lower surface of the master spring plate 10, which faces these protection plates 13, 13.

A tightening structure 15 for tightening the spring plates 10, 11 in the thickness direction is provided at an intermediate portion in the longitudinal direction of the spring plates 10, 11. This tightening structure 15
In this embodiment, the axle housing 16 and the pad 1 are an example of a pair of upper and lower tightening members.
7, U bolts 18, 18 and nuts 19, 1
9, etc.

and between the clamping surface of the clamping structure 15 and the spring plate, specifically between the pad 17 and the main spring plate 10, and the mounting surface 16 of the axle housing 16.
Abutment plates 21 and 22 are interposed between a and the child spring plate 11. A similar backing plate 23 is also provided between the spring plates 10 and 11. These backing plates 21, 22, 23 are attached to the U bolts 18, 1
The spring plates 10 and 11 have extension portions 21a, 22a, and 23a extending from the position 8 toward the plate ends of the spring plates 10 and 11. These extension portions 21a, 22a, 23a are also in contact with the spring plates 10, 11. and extension part 2
In order to gradually reduce the rigidity on the plate end side of 1a, 22a, 23a, a plurality of caul plate components 25... (see FIG. 3) each having a different length are superposed in the thickness direction. Each plate component 25... is
It is made of elastic materials such as synthetic resin, metal, or FRP. Note that these metal and non-metal materials may be appropriately combined and stacked. And the above caul plate component 2
5... in between, U bolts 18, 18 and nut 1
9 and 19, the spring plates 10 and 11 are strongly tightened.

When the caul plate components 25 having different lengths are stacked as described above, the rigidity at the end is the fourth
As illustrated in the figure, the height decreases stepwise toward the end of the plate. Further, the surface pressure at this portion gradually decreases toward the plate end side, as conceptually shown in FIG. 5, so that the surface pressure can be dispersed.

Therefore, by interposing the caul plates 21, 22, 23 made up of these caul plate components 25 on the tightening surface, a local increase in surface pressure is suppressed. In particular, it is possible to suppress a local increase in surface pressure in the vicinity of the tightening surface, such as the pad or the mounting surface of the axle housing, and is extremely effective in preventing damage in these areas.

In addition, as a means for gradually decreasing the rigidity of the plate end side of the caul plate, the cross-sectional area of the caul plate component may be gradually decreased toward the plate end side.

FIG. 6 shows an example of this, in which the extension portions of each caul plate component 25 extending from the positions of the U bolts 18, 18 to the end sides of the spring plates 10, 11 are defined by the thickness of the tip. The plate is tapered so that it gradually decreases, thereby softening the rigidity on the plate end side. In this case as well, the caul plate component 2
The material of 5 may be metal, or may be a synthetic resin alone or a non-metal such as FRP.

As described above, according to the present invention, it is possible to disperse the surface pressure on the tightening surface, which is highly effective in preventing damage to the FRP spring plate and maintaining durability.

[Brief explanation of the drawing]

Fig. 1 is a front view showing the tightening part in a conventional leaf spring device along with a surface pressure distribution diagram, Figs. 2 to 5 show an embodiment of the present invention, and Fig. 2 shows an FRP
A front view of the leaf spring device, FIG. 3 is a front view of a part of the tightening part, FIG. 4 is a diagram showing the rigidity of the section A-B in FIG. 3, and FIG. 5 is a diagram showing the rigidity of the section A-B in FIG. It is a figure showing surface pressure. FIG. 6 is a front view of a tightening portion showing another embodiment of the present invention. 10, 11...Spring plate, 15...Tightening structure, 1
6...Axle housing, 17...Pad, 1
8...U bolt, 19...Natsuto, 21, 22,
23...Packing plate, 25...Packing plate component.

Claims (1)

[Claims] 1. In an FRP leaf spring device equipped with an FRP spring plate and a tightening structure that tightens the spring plate in the thickness direction between a pair of upper and lower tightening members with U bolts, the tightening surface of the spring plate and A backing plate that is in contact with the spring plate is interposed between the spring plate and the opposite tightening surface, and this backing plate is placed on the side of the plate end of the spring plate from the position where the U bolt is provided. The extension part is also in contact with the spring plate, and the extension part has a tapered shape whose thickness gradually decreases toward the end of the plate. An FRP leaf spring device characterized by gradually decreasing the rigidity of the leaf end side.