JPH0260899B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to FRP used in vehicle suspension systems.
Regarding the stacked leaf spring device made by.

[Prior art] FRP spring plates are made of reinforcing fibers hardened with resin, and the reinforcing fibers have a diameter of 10 to 25 μm, for example.
Continuous fibers are used.

According to research conducted by the present inventors, in terms of tensile strength, using thinner reinforcing fibers is more durable than using thicker reinforcing fibers, while in terms of compressive strength, thicker reinforcing fibers are more durable. has been found to be advantageous. In addition, thick reinforcing fibers require fewer bundles and doublings, so they have better resin impregnation and alignment than thin reinforcing fibers, and have a shorter curing time, making them suitable for high-speed molding.

Therefore, when molding a single FRP spring plate, it is desirable to arrange thin reinforcing fibers on the tensile stress side of the spring plate and thick reinforcing fibers on the compressive stress side. .

However, in order to form FRP spring plates,
As illustrated in Fig. 1, roving a made of bundled reinforcing fibers is passed through a resin tank b to be impregnated with resin, and then pressed against mold c to form it. When reinforcing fibers of two or more different thicknesses are used, the number of rovings and resin tanks increases, leading to problems such as rovings becoming more likely to become tangled during mass production and the time and effort required to monitor the resin tanks increasing. For this reason, it is desirable to use reinforcing fibers of one type of thickness if possible to form one spring plate.

[Problems to be Solved by the Invention] In the case of a spring plate that uses reinforcing fibers of only one type of thickness, it is advantageous to use thin fibers when emphasis is placed on durability against tensile stress, such as in a suspension spring.

However, thin fibers have weaker compressive stress than thicker fibers, so if a spring plate made only of thin fibers is placed at the bottom of a stacked leaf spring system, stones bouncing off the road surface will be removed from the spring, as in a vehicle suspension system. If the bottom surface of the spring plate is likely to be hit, and the bottom surface of the spring plate is on the compressive stress side, when a stone, etc. hits the thin fibers on the bottom surface of the spring plate, the thin fibers, which are already weak against compression, will be damaged by the compressive stress. Problems may occur if the fibers are exposed to excessive heat or the buckling or hangnail standing of the fibers is promoted.

Therefore, the object of the present invention is to provide 1 spring plate as a single unit.
Reinforcing fibers of the same thickness can be used for each sheet, making mass production easy, and mass production is even easier by using thicker fibers.
Moreover, the object of the present invention is to provide an FRP stacked leaf spring device that can improve both durability and formability by protecting thin fibers that are vulnerable to compression.

[Means for Solving the Problems] The present invention, which was developed to achieve the above object, has the following features:
Made by stacking multiple FRP spring plates vertically.
In an FRP stacked leaf spring device, the upper spring plate is formed using reinforcing fibers that are thin and have the same diameter, and the lowermost spring plate is thicker than the fibers of the upper spring plate and has the same diameter as each other. This is an FRP stacked leaf spring device characterized by being molded using only reinforcing fibers.

[Function] Each spring plate is molded using reinforcing fibers of a single thickness. Although spring plates made of thick fibers have slightly lower tensile strength, they are easier to handle during molding than thin fibers, and require fewer yarns, making them suitable for mass production.

When the stacked leaf spring device of the present invention is installed on a vehicle in the same way as a normal suspension spring, the lower surface side of each spring leaf becomes compressive stress side due to the vehicle body load. In the present invention, the lowermost spring plate is made of thicker fibers than the upper spring plate. Thick fibers are less affected by contact with foreign objects than thin fibers under compressive loads, so they are less susceptible to damage even if foreign objects thrown up from the road surface come into contact with the lower surface of the spring plate, which is on the compressive stress side. .

[Example] A first example of the present invention will be described below with reference to FIG. 2. In Figure 2, 1 in the figure is
The main spring plate 1 is made of FRP, and eye members 2, 2 are attached to both ends of the main spring plate 1. Also, on the compressive stress side of the main spring plate 1, there is also FRP.
An auxiliary spring plate 3 made of aluminum is attached by a center bolt 4.

The main spring plate 1 is made of thin reinforcing fibers with high tensile strength and excellent durability, for example, 10 to 15 μm.
On the other hand, the auxiliary spring plate 3 is formed using only thick reinforcing fibers that have excellent formability and are suitable for mass production, for example, reinforcing fibers of about 20 μm or more. Note that, for ease of understanding, the spring plate using thick reinforcing fibers is shown with hatching in the drawing.

A total of tens to hundreds of the above-mentioned reinforcing fibers are 1
This strand is made into a book strand, and several to several tens of these strands are spliced together to form a roving.The roving is passed through a resin bath b as shown in Fig. 1, pressed against a mold c, and hardened to form a spring plate. obtain.

In the stacked leaf spring device shown in FIG. 2 constructed as described above, when a downward load is applied to both ends of the main spring plate 1, the lower surface of the main spring plate 1 gradually (compressive stress side) is the auxiliary spring plate 3
, and the spring constant increases, resulting in a nonlinear characteristic. Therefore, durability of the main spring plate 1 is more important than that of the auxiliary spring plate 3.

However, in this embodiment, as described above, the main spring plate 1 is molded using only thin reinforcing fibers, and the auxiliary spring plate 3 is molded using only thick reinforcing fibers. When used as a leaf spring device, the durability of the main spring plate is improved by the thin reinforcing fibers, and the single spring plate can be molded using the same type of reinforcing fiber, and the auxiliary spring plate 3 is made of thick reinforcing fibers. Since it can be used, it has good moldability and is suitable for mass production.

Moreover, since the lower surface (compressive stress side) of the main spring plate 1 made of thin fibers is covered by the auxiliary spring plate 3 made of thick fibers, favorable results can be obtained against stones thrown up from the road surface while driving. can get.

FIG. 3 shows a second embodiment of the present invention, in which a plurality of FRP spring plates 5a,
5b and 5c are stacked to form the main spring plate 5, and an auxiliary spring 6 is provided on the upper surface (tensile stress side) of the main spring 5 by stacking a plurality of FRP spring plates 6a, 6b, and 6c. Initially, only the main spring 5 acts as a spring, and when a certain load is reached, the members 7, 7 on the vehicle body side come into contact with the auxiliary spring 6, and the main spring 5 and the auxiliary spring 6 act simultaneously.

Therefore, in this second embodiment, thin reinforcing fibers are used for the auxiliary spring 6, which has a high working stress, to improve durability, and thick reinforcing fibers are used for the main spring 5 (not shown in the drawing). (Hatching has been added to make it easier to understand) The aim is to improve moldability.

Furthermore, FIG. 4 shows a third embodiment of the present invention, in which the longest first spring plate 5a of the main spring 5 is made of reinforcing fiber with an intermediate thickness, and the lower spring plates 5b and 5c are Thick reinforcing fibers are used for each of the spring plates 6a, 6b, and 6c of the auxiliary spring 6 located on the upper side. With such a configuration, the thickness of the reinforcing fibers can be distributed depending on the magnitude of the stress used, which is more effective in achieving both improved durability and improved formability.

[Effects of the Invention] According to the present invention, each spring plate alone can be efficiently molded using reinforcing fibers of the same thickness, and the reinforcing fibers can be used for each spring plate according to the magnitude of the stress used, the type of stress, etc. By changing the thickness of the reinforcing fibers, a highly durable stacked leaf spring device can be obtained. In addition, the use of thick reinforcing fibers further improves moldability, making it suitable for mass production, and also reduces the compressive stress side of spring plates, which use thin fibers that have high tensile strength but are weak in compression. It has great effects, such as being able to protect the surface by the spring plate made of thick fibers placed on the underside.

[Brief explanation of the drawing]

FIG. 1 is a schematic view showing an example of an FRP spring plate manufacturing apparatus, and FIGS. 2 to 4 are side views showing first to third embodiments of the present invention, respectively. 1...Main spring plate (main spring), 3...Auxiliary spring plate (auxiliary spring), 5...Main spring, 6...Auxiliary spring.

Claims (1)

[Claims] 1. In an FRP stacked leaf spring device in which a plurality of FRP spring plates are vertically stacked, the upper spring plate among the spring plates is made of thin reinforcing fibers with the same diameter. A stacked FRP leaf spring device, characterized in that the lowermost spring plate is formed using only reinforcing fibers that are thicker than the fibers of the upper spring plate and have the same diameter. 2. The FRP stacked leaf spring device according to claim 1, characterized in that the main spring is made of thin reinforcing fibers, and the auxiliary spring provided on the lower surface of the main spring is made of thick reinforcing fibers. 3. The FRP stacked leaf spring device according to claim 1, characterized in that the main spring is made of thick reinforcing fibers, and the auxiliary spring provided above the main spring is made of thin reinforcing fibers. 4 The main spring is composed of a plurality of spring plates, and only the first spring plate, which is the longest among these spring plates, is made of reinforcing fiber of intermediate thickness, and the spring plate is located on the lower surface side of the first spring plate. 4. The FRP stacked leaf spring device according to claim 3, wherein reinforcing fibers are thicker than the fibers of the first spring plate.