JPH0628965B2 - FRP leaf spring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a leaf spring device made of FRP used in a suspension mechanism of a vehicle.

[Prior Art] A leaf spring device used for a suspension mechanism portion of a vehicle has, for example, both end portions of a spring plate attached to a vehicle body side through eyeball members, and a U-shaped portion in a longitudinal middle portion of the spring plate, that is, a center clamp portion. The mounting base on the axle side is tightened and fixed using bolts, nuts, pads, etc.

In the center clamp portion of the conventional leaf spring device illustrated in FIG. 7, the spring plates 1 and 2 have U bolts 3 and 4 as clamp members screwed with nuts 5 (only a part of which are shown). It is strongly clamped between the mounting base 7 and the pad 8. The mounting base 7 is provided with axle-side members such as an axle housing (not shown). If necessary, a spacer 9 made of synthetic resin or the like may be provided between the mounting base 7 and the pad 8.

[Problems to be Solved by the Invention] In the above-mentioned tightening structure, when the tightening force, that is, the axial force applied to the U bolts 3, 4 is extremely large, as in a large track leaf spring device, the spring is deformed by the pad 8 The surface pressure applied to the plates 1 and 2 tends to be non-uniform. For example, when the surface pressure distribution of the spring plate 1 located on the pad 8 side is measured using a pressure-sensitive paper or the like, as shown in FIG. 8, in the width direction both sides of the spring plate 1, that is, near the U bolts 3 and 4, A portion 1a (shown by hatching) where the surface pressure is particularly high is generated.
In addition, 1b is a center hole.

In this way, when there are high surface pressure portions on both sides of the spring plate 1, bending is applied in the width direction of the spring plate 1. Therefore FR
For springs with anisotropy using unidirectional reinforcing fibers along the longitudinal direction of the spring plate, such as P (fiber reinforced synthetic resin) spring plates, when bending is applied in the plate width direction, Easy to crack in the direction.

Also, when a flat washer having a width narrower than the width of the spring plate is sandwiched between and strongly tightened by U-bolts, the angled portions of the both ends of the washer in the width direction extend in the longitudinal direction of the spring plate. Because of strong contact with the surface of the spring plate in the direction of biting, the spring plate of FRP may cause longitudinal cracks along the longitudinal fibers. Further, even when a spacer is provided between the spring plate and the washer, the widthwise both edges of the washer strongly push the spring plate through the spacer, so that cracks also tend to occur along the longitudinal fiber. .

MEANS FOR SOLVING THE PROBLEM The present invention is directed to a spring plate made of FRP, a mounting base that comes into contact with the spring plate directly or via a spacer, and a spring plate facing the end face in the width direction of the spring plate. Has a pair of clamp members such as U bolts having a leg portion extending in the plate thickness direction and a leg-to-leg portion that straddles the spring plate, and a nut screwed to the leg portion, and the spring plate has a longitudinal direction thereof. A FRP leaf spring device which is reinforced by fibers along and which clamps the spring plate between the mounting base and the inter-leg portion of the clamp member, at least between the inter-leg portion of the clamp member and the spring plate. A washer is provided on the spring plate, and a portion of the surface of the washer that is on the spring plate side is fastened by at least each leg-to-leg portion at the intermediate portion in the plate width direction of the spring plate with respect to the spring plate or the spacer. width It has a convex shape on the spring plate side so that it comes into contact with a surface of a smaller width, and is connected to both ends of the contact surface in the plate width direction. It is characterized in that an inclined surface is provided which is inclined in a direction gradually separating from the spring plate.

[Operation] According to the leaf spring device having the above-described configuration, when the spring plate is sandwiched between the mounting base and the leg portion of the clamp member and tightened with the nut, the spring plate is mainly tightened in the middle portion in the width direction. The surface pressure is received, and excessive surface pressure is not applied to the vicinity of both widthwise ends of the spring plate. Therefore, it is possible to prevent the FRP spring plate from having an excessive bending moment in the plate width direction, and to prevent the center clamp portion from being cracked in the longitudinal direction.

Further, since the angled portion is eliminated by continuously providing inclined surfaces on both sides of the contact surface of the washer, both sides of the contact surface bite into the spring plate surface along the longitudinal fibers of the FRP spring plate. It is no longer pushed strongly in the direction and F
It is effective in avoiding vertical cracks along the longitudinal fibers of the RP spring plate.

[Embodiment] In one embodiment shown in FIGS. 1 and 2, the spring plates 11 and 12 are made of FRP. These spring plates 11, 12
Is a reinforcing fiber bundle along the longitudinal direction of the spring plate that is hardened with a matrix resin. Reinforcing fibers other than those in the longitudinal direction may be included.

Both end portions in the length direction of the spring plates 11 and 12 are attached to the vehicle body side through eyeball members and the like (not shown). Further, a mounting base 21 is provided at intermediate portions in the length direction of the spring plates 11 and 12 by using U bolts 15 and 16 and pads 20 as an example of a clamp member.

The mounting base 21 is a metal block-shaped member having a high rigidity, and a member such as an axle housing on the axle side is fixed. The pad 20 is generally a pressed product made of sheet metal and is provided with recesses 24 and 25 for stopping the movement of the U bolts 15 and 16.

The U bolts 15 and 16 have a pair of left and right leg portions 15a and 15a.
a, 16a, 16a and horizontal inter-leg portions 15b, 16b straddling the spring plate 11. Each leg 15a16
a faces the widthwise end faces (ridge portions) of the spring plates 11 and 12, respectively, and extends in the plate thickness direction of the spring plates 11 and 12, that is, in the vertical direction.

In addition, the upper surface side of the spring plate 11 in the drawing and the lower surface side of the spring plate 12,
A spacer 28 made of synthetic resin or the like is provided between the spring plates 11 and 12. These spacers 28 are provided in order to prevent wear of the spring plates 11 and 12. Therefore, in the case of this embodiment, the mounting base 21 contacts the spring plate 12 via the spacer 28.

A nut 30 is screwed into each of the U bolts 15 and 16, and by tightening each nut 30, the spring plates 11 and 12 are tightened between the pad 20 and the mounting base 21. It should be noted that each nut 30 is provided with appropriate loosening prevention means.

A washer 32 is provided between the leg portions 15b and 16b of the clamp member and the spring plate 11.
The washer 32 is made of metal or a material having high rigidity corresponding to metal.

In the washer 32, the width W (see FIG. 2) of the surface 32a contacting the spring plate 11 via the spacer 28 is such that
It has a trapezoidal shape that is narrower than the width of. That is, the cross section of the washer 32 in the width direction has a trapezoidal shape that is convex toward the spring plate 11 and has a width W that is in contact with the spring plate 11.
a is flat and has inclined surfaces 32c on both sides of the surface 32a, the thickness of which gradually decreases in a tapered shape.

In the leaf spring device having the above configuration, the nut 30 is attached to the base 2
By tightening to the 1 side, the U-bolts 15 and 16 are provided between the mounting base 21 and the washer 32 so that the spring plates 11, 1
2 can be tightened. In this case, since the washer 32 is in contact with the spring plate 11 side at the surface 32a of the widthwise central portion thereof, even if the U bolts 15 and 16 are tightened considerably strongly, the washer 32 has a local surface at both widthwise end portions. Does not cause pressure rise.

That is, since the spring plate 11 is not bent in the plate width direction, even the FRP spring plate 11 can be prevented from cracking in the longitudinal direction at the center clamp portion.

Further, since the inclined surfaces 32c are continuously formed on both sides of the contact surface 32a, no local stress such that the both sides of the contact surface 32a bite into the spring plate is generated, and FR
This is effective in avoiding vertical cracks along the longitudinal fibers of the P spring plate 11. The above-mentioned effect is exhibited even when the spacer 28 is provided between the spring plate 11 and the washer 32.

Moreover, according to the above configuration, the spring plates 11 and 12, the U bolts 15 and 16, the pad 20, the mounting base 21, and the like can use the existing parts used in the conventional plate spring device as they are.

Further, by appropriately changing the plate thickness of the washer 32, the height dimension of the center clamp portion can be adjusted according to the mounting dimension to the vehicle and the like.

Although the spacer 28 is interposed between the washer 32 and the spring plate 11 in the above embodiment, the spacer 28 can be omitted by appropriately selecting the material of the washer 32, for example.
In some cases, it is possible to directly contact the washer 32 and the spring plate 11. Similarly, the mounting base 21 may directly contact the spring plate 12.

Further, the washer 32 may be provided between the mounting base 21 and the spring plate 12. In this case, the washer 32 is provided so that the surface 32a having the width W described above faces the spring plate 12 side.

Further, the washer 32 may have a shape as illustrated in FIGS. 3 to 6. That is, in the example of FIG.
The width of the washer 32 is made substantially the same as the width of the spring plate 11, and the cross section of the washer 32 in the width direction is shaped so that the thickness changes in an arc shape with a large curvature so that the spring plate 11 side is convex. Further, in the example of FIG. 4, the shape is such that the spring plate side is convex so as to be convex. However, in the drawing, the curvature of the convex surface 32a is exaggerated for easy understanding. Reference numeral 35 indicates a center hole.

In FIGS. 3 and 4, the convex surface 32 a contacts the spring plate 11. When the U bolts 15 and 16 are strongly tightened, both end portions in the width direction of the washer 32 are bent and deformed, so that a uniform surface pressure is obtained.

The washer 32 shown in FIG. 5 and FIG. 6 is a portion 32b near a portion located between the leg portions 15a and 15a of one U bolt 15 and between the leg portions 16a and 16a of the other U bolt 16. Only, the washer 32 has a trapezoidal or arcuate shape in which the cross section in the width direction is convex toward the spring plate side. Each of the washers 32 shown in FIGS. 5 and 6 is intended to prevent a local increase in the surface pressure generated near the legs 15a and 16a of the U-bolt.

Although the U-bolt is used as the clamp member in the above embodiment, the clamp member basically has a pair of left and right legs and an inter-leg portion that is located between these legs and straddles the spring plate. Therefore, in addition to the U-bolt integrally formed with the leg portion and the inter-leg portion portion, for example, a clamp member including a plurality of parts in which the leg portion and the inter-leg portion portion are separately formed Good. Further, the number of spring plates does not matter.

[Effects of the Invention] According to the present invention, it is possible to prevent a local increase in surface pressure due to tightening, and to prevent vertical cracks from occurring along the longitudinal fibers in the clamp portion of the FRP spring plate. There is.

[Brief description of drawings]

FIG. 1 is a side view of a tightening portion of an FRP leaf spring device showing an embodiment of the present invention, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIGS. A perspective view showing a modified example of the washer, FIG. 6 is a side view of the washer shown in FIG. 5,
FIG. 7 is a side view of a tightening portion in a conventional leaf spring device, and FIG. 8 is a schematic plan view showing a portion having a high surface pressure in the conventional tightening portion. 11, 12 ... Spring plate, 15, 16 ... U bolt (clamp member), 15a, 16a ... Leg portion, 15b, 16b
...... Leg portion, 21 ...... Mounting base, 28 ...... Spacer, 30 ...... Nut, 32 …… Washer, 32 a …… A surface that contacts the spring plate side.

Claims (5)

[Claims] 1. A spring plate (11) made of FRP, a mounting base (21) contacting the FRP spring plate (11) directly or via a spacer (28), and a width direction of the spring plate (11). A pair of clamp members having leg portions (15a) and (16a) facing the end face of the spring plate (11) extending in the plate thickness direction and inter-leg portion portions (15b) and (16b) straddling the spring plate (11) ( 15) (16) and a nut (30) screwed to the leg portions (15a) (16a), the spring plate (11) is reinforced by fibers along its longitudinal direction, In the FRP leaf spring device for tightening the spring plate (11) between the mounting base (21) and the inter-leg portions (15b, 16b) of the clamp members (15), (16), at least the clamp member (15) Inter-leg part of (16) (15
b) A washer (32) is provided between the spring plate (11) and the spring plate (11b), and at least the inter-leg portions (15b) (15b) of the surface of the washer (32) on the spring plate (11) side are provided. 16b) tighten the spring plate (1) to the spring plate (11) or spacer (28).
1) The spring plate (11) has a convex shape so that the surface (32a) having a width smaller than the plate width of the spring plate (11) comes into contact at the middle portion in the plate width direction, and the contact surface (32a) ) Of the washer (32) on both sides in the plate width direction, respectively, which are continuous with the contact surface (32a).
F is characterized in that inclined faces (32c) are provided so as to gradually separate from the spring plate (11) toward both ends in the plate width direction.
RP leaf spring device. 2. The washer (32) includes the clamp member (15) (1).
6) between the legs (15b) (16b) and the spring plate (11),
The FRP plate spring device according to claim 1, wherein the FRP plate spring device is provided between the mounting base (21) and the spring plate (12). 3. The washer (32) has a width substantially equal to the width of the spring plate (11), and the washer (32) has a cross-section in the width direction which is convex on the spring plate (11) side. The FRP leaf spring device according to claim 1 or 2 characterized by the above. 4. The cross section of the washer (32) in the width direction is a spring plate (1
1) The FRP leaf spring device according to claim 1 or 2, wherein the FRP leaf spring device has a warp such that the side is convex. 5. The washer (32) has a cross-section in the width direction of the washer (32) that is convex toward the spring plate (11) only near the location between the legs (15a) and (16a). The FRP leaf spring device according to claim 1 or 2, wherein the FRP leaf spring device has such a shape and the other portions are flat.