JPH0788131B2 - Vehicle suspension - Google Patents

Description

TECHNICAL FIELD The present invention relates to a suspension system for a vehicle used in a suspension system of a vehicle.

[Conventional technology]

Various types of suspension systems for vehicles have been conventionally known. For example, a traditional suspension device using a vertical steel spring plate is one in which eyeball parts are provided at both ends of the spring plate, and these eyeball parts are connected to the vehicle body side. The axle housing is fixed to the section.

In addition, in suspensions of an independent suspension system, a suspension spring using a steel coil spring is widely used as represented by, for example, a MacPherson strut or a double wishbone type suspension.

[Problems to be solved by the invention]

In order to improve the riding comfort, it is desired to increase the vertical stroke of the wheel. However, in the conventional suspension system using the steel spring plate, the spring plate needs to be considerably long in order to increase the vertical deflection. However, since the mounting space of the spring plate is naturally limited, the spring plate cannot be lengthened unnecessarily, and the weight is considerably heavy.

On the other hand, in order to increase the vertical stroke of the suspension device using the coil spring, the height of the coil spring becomes large. However, since there are restrictions on the space for accommodating the springs of the vehicle body frame and the suspension mechanism, the height at which the coil spring can be incorporated is naturally limited.

Under these circumstances, it has been desired to develop a suspension device that has a suspension spring that can be stored in a relatively narrow space and that can obtain sufficient bending.

Further, as described in Japanese Utility Model Application Laid-Open No. 57-69705, it has been proposed to urge the lower arm by a torsion spring made of FRP formed into a coil spring shape. Since the lower arm is provided at a position different from the rotating shaft, the entire device is bulky. In addition, it is necessary to provide a rebound stopper and the like separately to prevent the torsion spring from flexing excessively when the vehicle body temporarily floats up during rebounding while the vehicle is running. become.

[Means for solving problems]

The present invention has a horizontally extending pivot shaft provided on a member on the vehicle body side, a suspension link pivotally pivoted vertically about the pivot shaft, and a torsion coil spring shape. A suspension system for a vehicle comprising a suspension spring made of FRP, wherein the coil portion of the suspension spring made of FRP is wound around the outer peripheral portion of the pivot shaft, and the suspension spring has a body load of One end of this spring is locked to the member on the vehicle body side so that the inside of the coil part becomes the tension side and the outside of the coil part becomes the compression side in the loaded state, and the other end part is the link side. Is connected to the above-mentioned link so as to urge it to rotate to the ground side.

The link is, for example, an upper link (upper arm) or a lower link (lower arm). FRP above
The spring is made by burying unidirectional continuous reinforcing fibers such as glass fiber or carbon fiber mainly in the longitudinal direction of the spring to cure the matrix resin.

[Action]

In the suspension device configured as described above, when the link swings in the up-and-down direction as the wheel moves up and down, the suspension spring bends with this movement. In this FRP spring, the coil part is wound around the pivot shaft of the link, and the end part can be arranged along the member on the vehicle body side and the link, so that it can be applied to the suspension mechanism part where space constraints are severe. Can be incorporated.
However, this type of spring requires a considerably large amount of flexion because it is necessary to secure the vertical stroke of the wheel.

Here, when the suspension spring is made of steel, it is not suitable for practical use because the bending cannot be made large due to the relationship between the bending elastic modulus of steel and the allowable strain magnitude. However, an FRP material in which a unidirectional continuous reinforcing fiber bundle such as glass fiber or carbon fiber is embedded in a matrix resin can be flexed about twice as much as steel because of the relationship between the flexural modulus and the magnitude of strain.
In terms of material mechanics, the maximum allowable deflection when a constant load is applied to a plate of constant width and length is Proportional to. E is the flexural modulus, and ε is the strain that can withstand repeated use. In other words, since the bending amount of FRP that can withstand repeated bending is sufficiently larger than that of steel, bending acts by being connected to the link and the member on the vehicle body side like the above-mentioned torsion coil spring. In the suspension spring, sufficient bending can be obtained for practical use.

Moreover, the FRP spring in the present invention is twisted in the direction in which the coil portion rewinds when the vehicle body load is applied,
Since the inner surface of the coil part is the tension side, the characteristics of the FRP material, which is resistant to pulling, can be utilized, which is effective in increasing durability. Also, when the coil portion is twisted in the winding tightening direction with respect to displacement in the opposite direction such as during rebound, the coil portion bends in the direction in which the coil diameter decreases. This coil portion is wound around the pivot shaft, and it is possible to constrain it on the outer peripheral surface of the pivot shaft by reducing the coil diameter.

〔Example〕

In the vehicle suspension system shown in FIG. 1, pivot shafts 2 and 3 are provided at two positions above and below a member 1 (only part of which is shown) on the vehicle body side. The member 1 on the vehicle body side is a vehicle body frame, a subframe, or the like.

A link mechanism 5 for suspension is provided on the member 1 on the vehicle body side. That is, an upper link 6 is pivotally attached to the upper pivot shaft 2 and a lower link 7 is pivotally attached to the lower pivot shaft 3 so as to be vertically swingable. As shown in FIG. 2, the pivot shaft 2 is composed of a shaft 2a provided between a pair of bearing portions 1a and 1b, a cylindrical body 2b covered on the outer side of the shaft 2a, and the like. The shaft 2a is fixed by a nut 8.

Like the well-known double wishbone type, the links 6 and 7 project in the vehicle width direction, and the knuckle 9 is attached to the tip end of each link 6 and 7. Wheels 10 are rotatably supported on the knuckle 9. A shock absorber (not shown) is provided between the lower link 7 and the member 1 on the vehicle body side. Further, a similar suspension link mechanism is also provided on the right side of the member 1 on the vehicle body side in the drawing.

The link mechanism 5 is provided with a torsion coil spring-shaped FRP.
A suspension spring 11 made of plastic is used. This FRP spring 11
Is a unidirectionally reinforced fiber bundle mainly continuous in the longitudinal direction such as glass fiber or carbon fiber, which is impregnated with a matrix resin and then molded and cured into a predetermined shape. And arm portions 13 and 14 of. The arms 13, 14 are substantially straight or slightly curved. The cross-sectional shape of the coil portion 12 and the arm portions 13 and 14 is a quadrangle (thickness t, width b) as shown in FIG. As in the present embodiment, the FRP spring 11 having a rectangular or square cross section of the material is used.
Can be miniaturized and is easy to manufacture because the energy that can be stored is larger than that of a circular cross section.

The pivot shaft 2 is inserted through the coil portion 12 of the spring 11. That is, in the case of this embodiment, the coil portion 12 is wound on the outer side of the tubular body 2b. The inner diameter of the coil portion 12 is larger than the outer diameter of the tubular body 2b, and thus the coil portion 12 is a tubular body.
It can rotate with respect to 2b. The tubular body 2b is made of an FRP spring 11
It is desirable to use synthetic resin to prevent abrasion. When the tubular body 2b is made of metal, a liner (not shown) made of synthetic resin may be interposed between the tubular body 2b and the FRP spring 11 to prevent wear.

Further, one arm portion 13 is connected to the vehicle body-side member 1 by a connecting member 16, and the other arm portion 14 is connected to an end portion of the upper link 6 by a connecting member 17. Therefore, when the links 6 and 7 are rotationally displaced upward, the spring 11 is twisted in the unwinding direction, and the repulsive force thereof causes the links 6 and 7, that is, the knuckle 9
And the wheel 10 is urged downward, that is, toward the ground side. Therefore, in this embodiment, the coil portion is
The inside of 12 becomes the tension side (tensile side),
Since the outside of the coil portion 12 is the compression side (compression surface side), it is preferable for improving durability.

In a curved portion such as the coil portion 12, generally, the smaller the radius of curvature is, the larger the strain inside the curve becomes compared with the strain outside the curve. By the nature of the FRP material, the strength of the reinforcing fiber in the tensile direction, that is, the tension side is higher than that in the compression direction, that is, the compression side. For this reason, when using a FRP material that is weak in compression, it is more advantageous in strength to use it so that the inside of the bend becomes the tension side.

As mentioned above, when a constant load is applied to a material of constant width and constant length, the maximum amount of bending that can be repeatedly used is Proportional to. Table 1 below shows experimental results comparing the conventional spring steel with the test pieces of the glass fiber reinforced synthetic resin (GFRP) and the carbon fiber reinforced synthetic resin (CFRP) developed by the present inventors.

From Table 1, GFRP Is 2.4 times that of spring steel and CFRP is 1.6 times that of spring steel, and under the same load, GFRP can withstand the largest cyclic deformation.

A shape model of the FRP spring 11 is shown in FIG. The following table 2
Regarding the spring 11, the results obtained by comparing the GFRP and CFRP springs with the spring steel springs are shown. The elastic modulus E and the strain ε are the values shown in Table 1. The maximum load was 140 Kg- ^m torque. The developed length of the spring is constant at about 700 mm. The deflection δ is the amount of displacement at a position of 350 mm from the rotation center of the pivot shaft 2. Considering practicality, two types of plate width b, 30 mm and 20 mm, were examined.

When the FRP spring 11 having the above-described shape and size is used in the suspension device shown in FIG. 1, a maximum deflection δmax of 150 mm or more is desired in practice. As can be seen from Table 2, GFRP and CFRP
Steel springs satisfy this condition, but steel springs lack deflection. According to the research conducted by the present inventors, in order to obtain the bending that can be mounted on an actual vehicle by the spring 11, It is necessary to use the above materials. Such a value is not possible with steel, but can be achieved by using FRP.

As shown in Figs. 5 and 6, a pair of FRPs
The springs 11, 11 'may be combined. In this case, each spring 1
The winding directions of 1, 11 'are opposite to each other. A stopper 2 having one end 11a, 11a 'fixed to the member 1 on the vehicle body side
The springs 11 and 11 'are prevented from rotating by locking them to 0 and 20'. The other ends 11b and 11b 'are connected to the link 6 side by a connecting member 17.

Further, the present invention can be applied to a suspension device using a link other than the double wishbone type. In addition to the rectangular shape, the spring 11 may have a circular shape, an oval shape, an oval cross section, or the like.

〔The invention's effect〕

According to the present invention, a sufficient vertical stroke can be obtained even when using a suspension spring that can be incorporated in a suspension mechanism section where space is severely restricted, and the inner surface side of the coil section becomes the tension side, which improves durability. Since the coil is wound around the pivot shaft of the suspension link, it is effective for downsizing the entire device, and the coil is wound around the pivot shaft against displacement in the opposite direction such as rebound. Since it can be bent in the tightening direction, it can also function as a rebound stopper. In addition, the suspension spring is made of FRP, which has a great effect in making the suspension mechanism compact and lightweight.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a part of a suspension device according to an embodiment of the present invention in a partial cross section, FIG. 2 is a plan view of a part of the suspension device shown in FIG. 1, and FIG. FIG. 4 is a perspective view showing an example of a FRP spring, and FIG. 4 is a sectional view taken along line IV-IV of the spring shown in FIG. FIG. 5 is a plan view of a part of the suspension device showing another embodiment of the present invention, and FIG. 6 is a perspective view of a part of the suspension device shown in FIG. 1 …… Body member, 2,3 …… Pivot shaft, 6,7 …… Link, 10 …… Wheel, 11 …… FRP spring, 11a, 11b …… Spring end, 12 …… Coil part , 13,14 …… Arms (ends of springs).

Claims (1)

[Claims] 1. A pivot shaft provided in a member on a vehicle body side and extending in a horizontal direction, a suspension link pivotally mounted in a vertically swingable manner about the pivot shaft, and formed into a torsion coil spring shape. A suspension system for a vehicle, which comprises a suspension spring made of FRP, wherein the coil portion of the suspension spring made of FRP is wound around the outer periphery of the pivot shaft, and the suspension spring is attached to the vehicle body load. One end of this spring is locked to the member on the vehicle body side so that the inside of the coil becomes the tension side and the outside of the coil becomes the compression side when the A suspension system for a vehicle, wherein the link is connected to the link so as to urge the link to rotate toward the ground.