JPH0378500B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is used in suspension mechanisms of vehicles, etc.
Regarding FRP leaf spring device.

[Prior Art] Recently, in order to reduce the weight of vehicles, there is a tendency to use FRP spring plates in suspension mechanisms. However, the disadvantage of FRP is that it is susceptible to wear and impact.
Therefore, in the case of a multi-leaf spring with non-linear characteristics in which the spring constant increases as the load increases, where multiple spring plates repeatedly come into contact and non-contact, the spring plates are made of FRP. If it is made of aluminum, the mutual contact parts are likely to wear out and be damaged.

On the other hand, in a known stacked leaf spring device using steel spring plates, for example, Patent Application Publication No. 4235 of 1932
As seen in the publication, a coil spring is interposed between the upper and lower spring plates having different lengths, and the deflection of the main spring plate is transmitted to the child spring plate via this coil spring. , some have a spring constant that is gradually increased.

[Problems to be Solved by the Invention] However, in the above-mentioned known example, the coil spring is in contact with the main spring plate at the longitudinal middle portion (high stress portion), so in the case of a steel spring plate, However, in the case of an FRP spring plate, the reinforcing fibers of the FRP may break at the part where the terminal end turn of the coil spring comes into contact.
This causes serious defects in the main spring plate under high stress, such as fiber hangnails.

In addition, the coil spring of the above-mentioned known example is always in contact with the upper and lower spring plates, and the upper and lower spring plates are bent at the same time regardless of the magnitude of the load, so only the main spring plate is bent until a predetermined load is reached. It is not possible to obtain nonlinear characteristics such as

Therefore, an object of the present invention is to provide an FRP leaf spring device that can obtain progressive nonlinear characteristics without causing the above-mentioned wear and damage.

[Means for Solving the Problems] The present invention, which was developed to achieve the above object, has the following features:
Focusing on the eyeball attachment part where the bending stress of the master spring plate is lowest, a coil spring having the following structure is brought into contact with this eyeball attachment part. That is, the present invention includes a main spring plate made of FRP with a center member attached to the end,
An FRP leaf spring device having a child spring plate which is overlapped in the thickness direction of the main spring plate and has a length extending between both ends of the main spring plate, wherein the child spring plate is located at the center member attachment part of the main spring plate. A metal spring receiving plate is provided on the side surface, and a metal spring receiving plate is provided at the end of the child spring plate at a position facing the spring receiving plate.
A coil spring that is compressed when in contact with the spring receiving plate is installed, and the free end of the coil spring on the side of the spring receiving plate is provided with a coil spring that is separated from the spring receiving plate when the deflection of the main spring plate is small. A contact member is provided that comes into contact with the spring receiving plate in a state where the deflection becomes large.

[Function] When the load applied to the main spring plate is small, only the main spring plate bends, but when the load becomes large, the spring receiving plate comes into contact with the contact member of the coil spring at the center member attachment part of the main spring plate. It becomes like this. Therefore, as the load increases, the coil spring is compressed, and the load is also transmitted to the child spring plate, causing the child spring plate to bend as well. When the child spring plate is deflected, the deflection of the coil spring is added, so a nonlinear characteristic is obtained in which the spring constant changes smoothly when the spring constant changes from small to large.

When the above-mentioned main spring plate and child spring plate are bent, relative displacement occurs between the main spring plate and the child spring plate due to the span change at the center member attachment part, but the above-mentioned coil spring is Because it makes sliding contact with the spring receiving plate of the spring plate, it prevents problems such as the end turn of the coil spring being twisted or the body of the coil spring being bent when the master spring plate and child spring plate bend together. , the load is smoothly transmitted from the parent spring plate to the child spring plate.

[Example] An example of the present invention will be described below with reference to FIG. In Figure 1, 1 in the figure is
A main spring plate made of FRP is shown, and eye members 2, 2 made of metal or FRP are attached to both ends of this main spring plate 1. Each eyepiece member 2, 2 is fixed to the end portion of the main spring plate 1 using a metal spring bearing plate 3, a bolt 4, and a nut 5, respectively. Each of the eyeball members 2, 2 is adapted to be supported by the vehicle body side of a vehicle (not shown).

Also, in the thickness direction of the main spring plate 1, FRP
The child spring plates 6 made of the same material are provided one on top of the other. The child spring plate 6 has approximately the same length as the master spring plate 1, that is, the length spans both ends of the master spring plate 1. Both spring plates 1 and 6 are designed to reduce weight.
Each plate has a tapered leaf whose thickness gradually decreases on the edge side, and the stress is equalized at each part in the length direction. In addition, depending on the case, the child spring plate 6
may be made of steel.

Further, both spring plates 1 and 6 are restrained by a center bolt 7 at their mutually intermediate portions in the longitudinal direction, and an axle housing (not shown) is attached to this portion.

Coil springs 1 are attached to both ends of the child spring plate 6.
0 and 10 are attached. Since these coil springs 10, 10 have the same structure, one will be explained below as a representative.

This coil spring 10 has a coil spring main body 11
and a contact member 12 fixed to the free end of the coil spring body 11.
As illustrated in FIG. 2, a spring seat 15 is fixed to the end of the child spring plate 6 using a nut 13 and a washer 14, and the coil spring 10 is fixed to this spring seat 15. Therefore, the coil spring 10 is
It is provided at a position opposite to the attachment portion of the center member 2 on the main spring plate 1, that is, in this embodiment, at a position opposite to the lower surface side of the metal spring receiving plate 3. Note that the contact member 12 and the spring seat 15
is made of metal, FRP, or a single synthetic resin.

In the leaf spring device of this embodiment having the above configuration, when a downward load based on a vehicle body load or the like is applied to the center members 2, 2 at both ends, only the main spring plate 1 is bent while the load is small.

When the load increases and the deflection of the master spring plate 1 becomes large, the lower surfaces of the spring bearing plates 3, 3 begin to come into contact with the contact members 12, 12. However, both contact members 12, 12 do not necessarily come into contact at the same time. Then, when the load increases, the coil springs 10, 10 are deflected according to the magnitude of the load,
The reaction force is transmitted to the main spring plate 1 via the spring bearing plates 3, 3. Further, a force that causes the child spring plate 6 to bend downward is also applied.

Therefore, when at least one of the coil springs 10, 10 starts to come into contact, the spring constant increases, and becomes substantially the maximum spring constant when the coil springs 10, 10 are completely in close contact. Thereafter, as the load increases, the child spring plate 6 and the master spring plate 1 bend in the same way, resulting in a substantially constant load-deflection characteristic. Therefore, the leaf spring device described above can function as a flexible spring in a light load range and as a stiff spring in a large load range, providing progressive nonlinear characteristics and improving handling stability and ride comfort. Good results can be obtained. Also, the spring plates 1 and 6
By using FRP, it is possible to achieve a significant weight reduction compared to conventional steel springs.

According to the above embodiment device, the coil spring 1
0 and 10 are in contact with the metal spring bearing plates 3, 3 at the attachment portions of the eyepiece members 2, 2, which are the lowest stress points of the master spring plate 1. Therefore, there is little damage due to wear or impact, and this is extremely effective in protecting the FRP main spring plate 1 from breakage accidents.

When the coil spring 10 is made of FRP, further weight reduction can be achieved. In addition, the contact member 12
If an elastic body such as rubber or a synthetic resin such as elastomer is used for this purpose, it is effective to reduce the tapping noise.

In addition, as illustrated in FIG. 3, the coil spring 1
A conical coil spring may be used as the spring 0, and a tapered spring wire may be used such that the thickness of the spring wire becomes thinner toward the small diameter portion 10a. By doing so, the contact height of the coil spring 10 can be made lower than that of a normal coil spring (see FIG. 2), and a sufficient amount of deflection can be ensured. For the same purpose, a barrel-shaped coil spring or a chain-shaped coil spring can also be used.

Furthermore, as shown in FIG. 4, the surface 12a of the contact member 12 facing the main spring plate 1 may be inclined so that the spring receiving plate 3 can evenly contact this surface 12a. good.

Alternatively, as shown in FIG. 5, the axis of the coil spring 10 may be
Alternatively, the spring seat 15 may be attached to a spring seat 15 that is inclined so as to face in a vertical direction. In this case, the direction of the load applied to the coil spring 10 can be made to substantially match the axis of the coil.

Furthermore, as illustrated in FIG. 6, a rubber-like elastic body 20 may be interposed between the contact member 12 and the spring seat 15 so that the coil spring wires do not come into contact with each other even under maximum load. In this case, it is possible to prevent the occurrence of tapping noise and also to prevent a decrease in fatigue strength due to impactful contact. The elastic body 2
0 is fixed to either the contact member 12 or the spring seat 15.

In addition, the eyepiece member 2 illustrated in FIG. 7 is made of FRP
It consists of an eyeball main body 21 made of plastic, and a bush 22 made of metal or the like held by the eyeball main body 21. In this case, the FRP eyeball body 21 directly connects the coil spring 1.
0, a metal spring bearing plate 3 is fastened together with the eyeball body 21 by bolts 4 and nuts 5.

In each of the above embodiments, a metal plate is used as the spring bearing plate 3. However, in the case of a metal eyepiece member, for example, the attachment base of the eyepiece member should be opposed to the coil spring 10, and this portion The contact member 12 of the coil spring 10 may be brought into contact with the contact member 12 of the coil spring 10. In this case, a part of the eyepiece member also serves as a spring bearing plate.

Furthermore, as schematically shown in FIG. 8, the spring constants of the coil springs 10, 10 may be made to differ from each other in order to cope with the wind-up phenomenon that occurs when the vehicle suddenly starts or brakes. good. In this case, wind-up performance can be improved by increasing the spring constant or free height of the side that receives larger deflection during wind-up.

Furthermore, the present invention can of course be applied to a stacked leaf spring device having two or more child spring plates.

[Effects of the Invention] According to the present invention, the contact member of the coil spring comes into contact via the metal spring bearing plate at the center attachment portion of the master spring plate with low bending stress, so there is no difference between contact and non-contact. Even if contact is repeated, it is possible to prevent problems such as wear and damage that would occur if the main spring plate is made of FRP, and stress concentration can also be prevented. Since the coil spring comes into contact with the spring receiving plate via the contact member provided at its free end, the coil spring and the spring are Even if the receiving plate moves relative to the longitudinal direction of the spring plate, the contact member can slide, which prevents problems such as the end turn of the coil spring being twisted or the body of the coil spring being bent. Load can be smoothly transmitted between the parent spring plate and the child spring plate via the spring.

[Brief explanation of drawings]

FIG. 1 is a front view of an FRP leaf spring device showing one embodiment of the present invention, and FIGS. 2 to 6 are sectional views showing mutually different aspects of the coil spring portion, respectively.
FIG. 7 is a sectional view showing a modified example of the eyepiece member;
The figure is a front view schematically showing the wind-up state. DESCRIPTION OF SYMBOLS 1... Main spring plate, 2... Eye member, 3... Spring receiving plate, 6... Child spring plate, 10... Coil spring, 12... Contact member.

Claims (1)

[Claims] 1 A master spring plate 1 made of FRP with a center member 2 attached to its end, and a child spring plate 6 which is overlapped in the thickness direction of the master spring plate 1 and has a length extending between both ends of the master spring plate 1. An FRP leaf spring device having
A metal spring bearing plate 3 is provided on the side of the child spring plate 6 of the eyepiece attachment part of the main spring plate 1, and a metal spring bearing plate 3 is provided at the end of the child spring plate 6 at a position opposite to the spring bearing plate 3. A coil spring 10 that is compressed when in contact with the spring receiver plate 3 is attached to the spring receiver plate 3, and the spring receiver plate is attached to the free end of the coil spring 10 on the side of the spring receiver plate 3 when the deflection of the parent spring plate 1 is small. 3. An FRP leaf spring device characterized in that a contact member 12 is provided which is separated from the spring support plate 3 and comes into contact with the spring bearing plate 3 when the deflection of the master spring plate 1 is increased.