JPH01105029A - Leaf spring device - Google Patents

Abstract

PURPOSE:To prevent a leaf spring and a spring eye member from wearing caused by their rubbing by fixing an end part of the leaf spring to be tightened to an eye frame by a bolt penetrating in the plate thickness direction through the end part of the leaf spring and the eye frame in its mounting position. CONSTITUTION:A retaining member 14, equipped with a wedge-shaped member 16, is pulled in a direction of biting between an eye frame 3 and a leaf spring 1 and fixed by a tightening means 20. As the result, an end part of the leaf spring 1 is firmly held by a socalled wedge effect in the thickness direction between a bottom wall 5 of the eye frame 3 and the retaining member 14. Further the end part of the leaf spring 1, in its location providing the eye frame 3, is tightened in its thickness direction by a bolt 28 penetrating through the leaf spring 1 in its thickness direction. By a synergistic effect of these leaf spring and eye frame, very strongly fixing the leaf spring 1 to the eye frame 3, the leaf spring 1 can be prevented from its wear due to mutual rubbing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a leaf spring device used, for example, in a suspension spring for a vehicle.

[Prior Art] Leaf spring devices used in vehicle suspension springs are made of composite materials such as fiber-reinforced plastic (FRP) instead of conventional steel spring plates in order to reduce weight. There is a tendency for the use of spring plates that are

However, with such a spring plate made of a composite material, it is difficult to integrally wind and mold the center portion at the end of the plate.

Therefore, a center member made separately from the spring plate is attached to the end of the spring plate using bolts or the like.

For example, Patent Application Publication No. 81-501335 (
A plastic plate spring using an eyeball bush as shown in Prior Art 1) or Japanese Patent Application Laid-Open No. 61-2115
As shown in Japanese Patent No. 41 (Prior Art 2), an eyepiece member for a leaf spring, which is composed of a main body made of a bent metal plate and a cylindrical member, has been proposed.

[Problems to be Solved by the Invention] However, in some cases of the prior art 1, it is necessary to open holes for bolt insertion at the end of the spring plate where the load is applied. In composite materials that are reinforced with steel, the load concentrates near the holes, and damage may occur from the periphery of the holes. - On the other hand, in the case of Prior Art 2, there is no need to make holes in the spring plate, which is advantageous in terms of strength. However, during use, the spring plate and the eyepiece rub against each other in the longitudinal direction, albeit very slightly, and as a result, the surface of the FRP is worn out, leading to breakage of the reinforcing fibers. Therefore, in the above-mentioned prior art 2, in order to prevent the eyepiece member from shifting in the longitudinal direction, a protrusion that protrudes toward the spring plate is provided on a part of the eyepiece member, and this protrusion is fitted into a recess in the spring plate. has also been done. However, in this case, the protrusion locally contacts the spring plate, which may cause damage to the spring plate.

Therefore, an object of the present invention is to be able to firmly fix an eyeball member to a spring plate, and to prevent wear caused by rubbing between the spring plate and the eyeball member.

[Means for solving the IJIi point] In order to achieve the above object, the present invention provides a leaf spring device having the following configuration. That is, the present invention can be applied to, for example, FR
This leaf spring device includes a spring plate l made of a composite material such as P, and an eye assembly 2 attached to an end of the spring plate 1, the eye assembly 2 being attached to one side of the spring plate l. A metal eye frame 3 includes a bottom wall 5 that overlaps with the bottom wall 5 and a pair of left and right side walls 6.7 that are continuous with the bottom wall 5, and a metal eye frame 3 that overlaps the other side of the spring plate 1 and extends from one end side to the other end side. The presser member 14 has wedge-shaped parts 16 and 17 whose height changes in a tapered manner, and this wedge-shaped part 18.17 fits between the eye frame 3 and the spring plates 1 and Q2, and the wedge-shaped part 18. The means 2 is used to tighten the presser member 14 in the direction in which the member 17 bites between the spring plate 1 and the eyeball frame 3.
0, and a spring plate 1 that passes through the end of the spring plate l and the eyeball frame 3 in the plate thickness direction at the part where the eyeball frame 3 is attached.
A bolt 28 is provided to fasten the end of the frame 3 to the eye frame 3.

[Function] The leaf spring device having the above-mentioned structure has a so-called wedge shape by pulling and fixing the presser member having the wedge-shaped portion in the direction of biting between the eye frame and the spring plate by means of the tightening means. As a result, the end of the spring plate is strongly pinched in the thickness direction between the bottom wall of the eyeball frame and the presser member. Moreover, the end portion of the spring plate is tightened in the thickness direction of the eye frame by a bolt passing through the spring plate in the thickness direction at a portion where the eye frame is provided. Due to these synergistic effects, the spring plate and the eyepiece frame are fixed extremely firmly, which is extremely effective in preventing the spring plates from being worn out due to rubbing against each other.

[Embodiment] Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 3. The spring plate 1 made of a composite material is molded using, for example, a matrix resin and continuous reinforcing fibers mainly extending in the longitudinal direction.

Eyepiece assemblies 2 (only one is shown) are attached to both ends of the spring plate 1, respectively. This eyeball assembly 2 is constructed by combining metal parts described below.

Note that the upper surface side of the spring plate 1 in the figure is the tension side because tensile stress mainly acts upon it during use, and the lower surface side of the spring plate 1 is the compression side because the compressive stress mainly acts thereon.

The eyeball frame 3 that constitutes the main part of the eyeball assembly 2 is
It consists of a frame body 3a formed into a box shape by bending a thick metal plate, and a cylindrical body 9 described below fixed to the end of this frame body 3a. The frame main body 3a also includes a flat bottom wall 5 superimposed on one surface side (lower surface side in the figure) of the spring plate 1, a pair of side walls 6.7 rising on both left and right sides of the bottom wall 5, and a bottom wall 5. and an upper wall 8 facing the. A cylindrical body 9 is welded between the side walls 6,7. Since the cylindrical body 9 is connected to a bracket or a shackle (not shown) on the vehicle body side and is where the load of the vehicle body is applied, the center of the cylindrical body 9 becomes the load point M. Side walls 6, 7
has a tapered shape in which the height decreases from one end (the side where the cylindrical body 9 is provided) toward the other end when viewed from the side. Therefore, the height of the upper wall 8 also decreases in a tapered manner from one end side toward the other end side C9.

The presser member 14 accommodated within the frame body 3a of the eyeball frame 3 has a wedge shape as shown in FIG. That is, it consists of a flat plate part 15 superimposed on the upper surface side of the spring plate 1 in the figure, and wedge-shaped parts 16 and 17 rising on both left and right sides of this flat plate part 15. The wedge-shaped portions 16, 17, like the side walls 6, 7 described above, have a tapered shape in which the height decreases from one end toward the other end. A screw hole 18 is opened in each of the front end faces of the wedge-shaped portions 16,17. Further, at the rear edge of the flat plate portion 15,
A groove 19 is formed along the longitudinal direction of the flat plate portion 15 for passing a bolt 28, which will be described later.

In this embodiment, the tightening means 20 for pulling the wedge-shaped portions 16 and 17 includes a pair of left and right bolts 21, and a cross-sectional support plate 22 having a rising wall 22a supporting the bolts 21. The screw hole 1 into which the bolt 21 is screwed
It is composed of 8 etc. The above rising wall 22a
is arranged so as to hit the upper part of the front end surface of the frame body 3a.

Therefore, when the bolt 21 is turned in the tightening direction, the presser member 14
is pulled to the left in the figure, so that the wedge-shaped portions 16 and 17 are strongly wedged between the upper wall 8 of the eyepiece frame 3 and the spring plate 1.

Furthermore, at the end of the spring plate 1 and the bottom wall 5 of the eyepiece frame 3,
Holes 26 and 27 passing through the plate in the thickness direction are respectively provided, and bolts 28 are inserted through these holes 26 and 27. The tip side of this bolt 28 is connected to the groove 19 of the holding member 14.
It protrudes to the upper side through the hole and is screwed into the nut 29. By tightening these bolts 28 and nuts 29, the eye frame 3 and the presser member 14 are pressed in the thickness direction of the spring plate 1.

The position where the bolt 28 is provided, that is, the hole 2 for inserting the bolt
The position of 6 is such that the distance L from the end of the spring plate 1 (see FIG. 1) falls within the range of 10 mm to 50 mm.

Further, a sheet-like liner 31 is interposed between the lower surface of the spring plate 1 and the bottom wall 5, and a liner 32 is also interposed between the upper surface of the spring plate 1 and the pressing member 14. These liners 31 and 32 are for preventing the metal eye frame 3 and the presser member 14 from coming into direct contact with the spring plate 1, and prevent the spring plate 1 from being worn out. The tightening applied to helps equalize the forces. Therefore, the liners 31 and 32 have a hardness lower than that of the spring plate 1, and have appropriate elasticity and flexibility.
For example, a material made of elastomer reinforced with fibers is used so that it will not be crushed even if repeated loads are applied. These liners 31, 32 are glued to the spring plate 1.

In the eyeball assembly 2 having the above configuration, the end of the spring plate 1 is inserted into the eyeball frame 3, the support plate 22 and the flat plate part 15 of the presser member 14 are overlapped, and the bolt 21 is rotated in the tightening direction. The wedge-shaped portions 16, 17 of the presser member 14 are strongly wedged between the upper wall 8 of the eyepiece frame 3 and the spring plate 1 due to the so-called wedge effect. When a force is applied in the direction in which the spring plate 1 comes off the eyeball frame 3, the presser member 14 is moved between the upper wall 8 and the spring plate 1 due to the wedge effect.
It bites into the space more and more. Moreover, the ends of the spring plate 1 are strongly tightened in the thickness direction of the eye frame 3 by the bolts 28. In addition, the entire circumference of the end of the spring plate 1 is surrounded by the bottom wall 5 and side walls 6, 7 of the box-shaped eye frame 3, the flat plate portion 15 of the presser member 14, the support plate 22, etc. and the bottom wall 5 and between the spring plate 1 and the support plate 22 are fitted with liners 31,32.

Due to these synergistic effects, the bonding strength between the spring plate 1 and the eyeball assembly 2 is extremely high, and the spring plate 1 is less likely to be damaged or worn due to rubbing.
It can demonstrate excellent durability.

Note that FIG. 4 shows a second embodiment of the present invention.

In this embodiment, the end of the spring plate 1 passes below the cylindrical body 9 and extends to near the end surface of the eyepiece frame 3.

The bolt 28 is lower than the load point M of the cylindrical body 9 on the spring plate 1.
The tip of the bolt 28 is screwed into a screw hole 35 provided in the cylindrical body 9. Therefore, with respect to the vertical load applied to the eye frame 3 via the cylindrical body 9, an unreasonable load is not applied to the through hole 26 for passing the bolt 28, and damage from the periphery of the hole 26 is prevented. It is effective on Since the other configurations and effects are the same as those of the first embodiment described above,
The same parts as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

Further, FIGS. 5 and 6 show a third embodiment of the present invention, and the eye frame 3 of this embodiment includes a box-shaped first member 36 and a first member inserted into the first member 36. 2
It consists of a member 37. A cylindrical body 9 is fixed to this second member 37. Further, a rising wall 37a is provided at the front end of the second member 37, and the bolt 21 is supported by this rising wall 37a. The distal end of the bolt 21 is screwed into the threaded hole 18 of the holding member 14 having a wedge-shaped portion 16, 17, as in the first and second embodiments described above.

Therefore, when the bolt 21 is rotated in the tightening direction, the presser member 14 is drawn to the left in the figure, and the wedge-shaped portion 16.1
7 is strongly wedged between the spring plate 1 and the upper wall 8 of the eyepiece frame 3. Also in the case of this third embodiment, the bolt 28 is connected to the cylindrical body 9.
By providing it closer to the plate end than the load point M, the load near the bolt insertion hole 26 is lightened.

In addition, in any of the above embodiments, the tightening is performed by the means 20.
In short, any clamp mechanism other than the above-mentioned embodiments is also applicable, as long as it can press the wedge-shaped portions 16 and 17 in a direction that bites them between the spring plate 1 and the eyepiece frame 3.

Further, in each of the above embodiments, the cylindrical body 9 and the wedge-shaped portion 16
．． 17 are provided on the upper surface side of the spring plate 1 in the drawing, but the structure is not limited to this. For example, the cylindrical body 9 may be provided on the upper side of the spring plate 1 in the figure, and the wedge-shaped portions 16 and 17 may be provided on the opposite side (the lower side in the figure) of the spring plate 1. This prevents the flaket or shackle on the vehicle body side connected to the cylindrical body 9 from interfering with the wedge-shaped portions 16 and 17. Furthermore, if the bolt 21 used for wedge tightening is constructed so that the bolt 21 is tilted at an angle so that the head of the bolt 21 is separated from the spring plate 1, tightening the bolt 21 with a tool such as a spanner becomes easier.

FIG. 7 shows an example using a tapered FRP spring plate 1.

This spring plate 1 has a tapered portion 1b formed in such a shape that the thickness decreases from a center portion 1a located at a longitudinally intermediate portion toward the end of the plate. In addition, center part 1a
Seat plates 40 and 41 are superimposed on the upper and lower surfaces of the seat plate, and a center bolt 42 is inserted through the seat plates 40 and 41. The structure of the eyeball assembly 2 may be similar to each of the embodiments described above. When such a tapered spring plate 1 is employed, stress in the longitudinal direction of the spring plate 1 can be equalized as shown by the solid line in FIG. 8, which is preferable in terms of weight reduction. In addition, in the case of a spring plate having approximately the same thickness in the longitudinal direction, the stress decreases toward the plate end side, as shown by the broken line in the figure.

Since the tapered spring plate 1 has a thinner plate thickness at the end of the plate, the shear stress when bent in the vertical direction is higher than that of a spring plate of equal thickness. For this reason, the bolt 28 is attached to the plate end IC.
Test results have revealed that if a hole 26 is provided for the bolt to pass through, there is a possibility that shear failure due to fatigue may occur starting from this bolt hole 26.

The above-mentioned shear failure is a type of failure in which the spring plate 1 is divided into upper and lower halves, as shown by the dashed-dotted line in Fig. 7, and is unique to FRP and cannot be seen in steel spring plates. It is destruction. The reason why such destruction occurs is that the FRP spring plate is a composite material mainly reinforced with fibers continuous in the longitudinal direction, and there is a possibility that so-called delamination may occur. In particular, in the case of the tapered spring plate 1 mentioned above, where the thickness of the plate end side is thinner,
Since the shear stress on the plate end side is high, the bolt hole 26
Delamination is likely to occur starting from this point. Note that the shear stress τ can be calculated using the following formula.

r-1,5xP/ (BX t) -(1)P: Load acting on the spring plate B: Plate width t: Plate thickness In order to prevent complete failure, -FR shown in Fig. 9 is applied.
As with the P-taper spring plate 1, it is effective to make the plate thickness t2 of the plate end portion IC on the combination side thicker than the plate thickness ti of the tapered portion 1b continuous to this plate end portion IC. In this case, the magnitude of t2 is preferably designed so that τ is 1.5 to 2 kgf'/d or less from the above equation (1). Note that the static shear fracture strength of FRP is 6 to 7 kgf/-. Further, as in the embodiment shown in FIG. 10, the thicknesses of both the tension side and the compression side of the plate end portion IC may be increased.

The FRP Taber spring plate 1 shown in FIG. 11 is rounded with a relatively large radius of curvature R1 so that reinforcing fibers 45 (only a portion is shown) are sufficiently spread over at least the tension-side plate thickness change portion 44. ing. In this case, it is effective to make R1 larger than the radius of curvature R2 of the plate thickness changing portion 46 on the compression side.

In the embodiment shown in FIG. 12, a thickened portion 47 is provided mainly in the vicinity of the bolt hole 26 in the plate end portion IC of the FRP tapered spring plate 1.
The plate thickness t2 of the tapered portion 1b is made thicker than the plate thickness tl of the tapered portion 1b. In this case, the above-mentioned portion 4 is attached to the bottom wall 5 of the eyeball frame 3.
By providing four parts 48゛ into which 7 is fitted,
The eye assembly 2 becomes more difficult to come out in the direction of arrow F in the figure.

Further, as shown in FIG. 13, a thickened portion 47 may be provided on a part of the tension side of the FRP tapered spring plate 1, or as shown in FIG.

Part 4 where the thickness is increased on the compression side
Even if 7 is provided, the same effect as described in FIG. 12 can be expected. Furthermore, as shown in FIG.
A thickened portion 47 may be provided on the entire tension side of C.

If the thickness of the plate end portion IC is made thicker than the thickness of the tapered portion 1b connected thereto as in each of the embodiments shown in FIGS. 9 to 15 described above, shear failure as shown in FIG. 7 will occur. It is effective in preventing the occurrence of Also, from the purpose of preventing shear failure, the plate end portion I
Increasing the plate thickness of C is also effective in an FRP Taber spring plate that does not use bolts 28 (bolt holes 26 are not provided).

[Effects of the Invention] According to the present invention, the eye assembly can be firmly fixed to the end of the spring plate, and the spring plate will not wear out due to slight friction during use or due to local stress concentration. This is highly effective in preventing damage, etc.

[Brief explanation of the drawing]

Figure 1 is a side view of the end of the leaf spring device showing the first embodiment of the present invention, Figure 2 is a perspective view partially showing the end of the leaf spring device shown in Figure 1, and Figure 2 is a perspective view showing the end of the leaf spring device shown in Figure 1. 3 is a perspective view of the holding member in FIG. 1, FIG. 4 is a side view of the end of a leaf spring device showing a second embodiment of the invention, and FIG. 5 is a third embodiment of the invention. FIG. 6 is a side view of the end of the leaf spring device, FIG. 6 is a perspective view partially showing the end of the leaf spring device shown in FIG. 5, and FIG.
A side view showing the fourth embodiment of the present invention applied to a spring plate, FIG. 8 is a diagram showing the stress distribution of the spring plate shown in FIG. 7, and FIG. 9 is a side view showing the fourth embodiment of the present invention applied to a spring plate. FIG. 10 is a side view of the end portion of the leaf spring device showing a modification of the spring plate; FIG. 11 is a side view showing the arrangement of fibers at the end portion of the leaf; FIGS. FIG. 15 is a side view showing different modifications of the plate end portions. DESCRIPTION OF SYMBOLS 1...Spring plate, 1a...Center part, 1b...Tapered part, IC...Plate end part, 2...Eye assembly, 3...Eye frame, 5...Bottom wall , 6, 7...
Side wall, 14... Pressing member, 16.17... Wedge-shaped portion, 20... Tightening means, 28... Bolt, M.
...The load point of the eyeball frame. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Figure 3 Figure 40 Figure 5 60 Figure 9 10121 Figure 11 Figure 120 Figure 13 Figure 14 Figure 15

Claims (4)

[Claims] (1) A leaf spring device comprising a spring plate and an eyelet assembly attached to an end of the spring plate, the eyelet assembly comprising a bottom wall superimposed on one side of the spring plate and the eyelet assembly. It has a metal eye frame with a pair of left and right side walls connected to the bottom wall, and a wedge-shaped part overlapped with the other side of the spring plate and whose height changes in a tapered shape from one end to the other end. a presser member whose wedge-shaped portion inserts between the eyeball frame and the spring plate; and a tightening means which pulls the presser member in a direction where the wedge-shaped portion bites between the spring plate and the eyelet frame. , characterized in that a bolt passes through the end of the spring plate and the eye frame in the plate thickness direction and tightens and fixes the end of the spring plate to the eye frame at a portion where the eye frame is attached. Leaf spring device. (2) The leaf spring device according to claim 1, wherein the bolt is inserted closer to the end of the spring plate than the load point of the eye frame. (3) The spring plate is made of FRP reinforced mainly with fibers along the longitudinal direction of the spring plate.
Leaf spring device as described in section. (4) The above-mentioned FRP spring plate has a tapered portion having a tapered shape such that the thickness decreases from the center portion toward the plate end side, and the plate end portion to which the eyeball assembly is attached. 4. The leaf spring device according to claim 3, wherein the plate thickness is greater than the plate thickness of the tapered portion continuous to the plate end portion.