JPH0874918A - Bumper spring - Google Patents

Abstract

PURPOSE: To provide a bumper spring by which non-linear spring characteristic can be obtained profitably. CONSTITUTION: A restraint ring 16 is provided by having a leg part 50 fitted in and engagingly locked to a recessed groove 40 formed in a bumper spring main body 14 and having a head part 52 extended from the outer periphery part of the leg part 50 in axial direction both sides and facingly positioned to the outer peripheral surface of the bumper spring main body 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bumper spring for a vehicle suspension, which is disposed outside a piston rod of a shock absorber so as to elastically limit an operation stroke of the shock absorber.

[0002]

BACKGROUND ART In a shock absorber that constitutes a vehicle suspension, generally, a cylindrical bumper spring formed of a rubber elastic body is externally arranged on a piston rod. The bumper spring is axially compressed and deformed between the cylinder of the shock absorber and the member on the vehicle body side or the wheel side where the piston rod of the shock absorber is attached, so that the operating stroke of the shock absorber is elastically changed. It is becoming restricted.

By the way, the bumper spring has
In order to achieve both good riding comfort and steering stability of the vehicle, a nonlinear spring characteristic is required, which is soft when the stroke of the shock absorber is small and hard enough when the stroke is large, and does not interfere with other members such as dust covers. It is required to secure a sufficiently large working stroke of the shock absorber while preventing it.

[0004] Therefore, from the past, there has been a conventional method, 61-2038.
As described in Japanese Patent Publication No. 07, etc., a restraint ring made of synthetic resin or the like is closely placed in a groove extending in the circumferential direction formed on the outer peripheral surface of the bumper spring body to expand the bumper spring body outward. By limiting the deformation of the bumper spring, the deformation of the bumper spring body is restricted when a large load is input to achieve hard spring characteristics and prevent interference with other members, while increasing the deformation stroke of the bumper spring body. A bumper spring has been proposed which realizes a low spring characteristic when a small load is input.

However, in the bumper spring having such a structure, if the restraint ring is attached to the body of the bumper spring in a non-adhesive manner, or if the adhesive force is weak and partially non-adhesive, a load is applied. The problem that the bumper spring body easily wraps around both sides of the restraint ring in the axial direction and bulges outward and is difficult to effectively limit the deformation, and the desired effect as described above cannot always be exhibited. Therefore, there was a problem that a reliable and strong bonding process of the restraint ring to the bumper spring body was indispensable, which made the manufacturing process troublesome and unavoidable cost increase. There is also a problem that it is difficult to secure sufficient reliability and durability because the desired characteristics are not exhibited.

[0006]

The present invention has been made in view of the circumstances as described above, and the problem to be solved is that even when the restraint ring is not adhered to the bumper spring body. SUMMARY OF THE INVENTION It is an object of the present invention to provide a bumper spring having an improved structure in which the effect of restricting outward bulging deformation of a bumper spring body can be effectively exerted, and a nonlinear spring characteristic can be advantageously realized.

[0007]

In order to solve such a problem, a feature of the present invention resides in that it is externally arranged on a piston rod of a shock absorber forming a vehicle suspension to elastically change an operation stroke of the shock absorber. In the limiting bumper spring, a groove is formed on the outer peripheral surface of a cylindrical bumper spring body made of an elastic body, the groove extending axially at an intermediate portion in the axial direction, and is fitted into the groove and locked. A restraining ring having a leg portion and a head portion that extends from the outer peripheral portion of the leg portion to both sides in the axial direction of the concave groove and is positioned to face the outer peripheral surface of the pumper spring body in the direction perpendicular to the axis. There is something.

Further, in a first preferred mode of the bumper spring according to the present invention, a curled portion extending in the circumferential direction is provided on each of both sides of the bumper spring body in the axial direction sandwiching the concave groove, and each of them is provided. An opening edge portion of the currant portion on the concave groove side is positioned to face an inner peripheral surface of the head portion of the restraining ring.

Further, in a preferred second aspect of the present invention, in the bumper spring according to the second aspect, the currant portion is formed to have a V-shaped cross section.

Further, in a preferred third aspect of the present invention, the concave groove of the bumper spring body into which the leg portion of the restraining ring is fitted has a thickness dimension at a mounting portion of the restraining ring in the bumper spring body. 40-80
Formed with a depth of.

Further, in a preferred fourth aspect of the present invention, even if a load is not input to the bumper spring, the facing surfaces of the head portion of the restraining ring and the bumper spring body contact each other. , The restraint ring is assembled.

Further, in a preferred fifth aspect of the present invention, the bumper spring body is composed of a thick-walled straight upper cylindrical portion and a thin, bellows-shaped lower cylindrical portion, and The restraint ring is mounted near the boundary between the upper cylindrical portion and the lower cylindrical portion.

[0013]

In the bumper spring having the structure according to the present invention as described above, even when the restraint ring is not adhered to the bumper spring body, the leg portions of the restraint ring are axially opposite to each other at the time of load input. The elastic deformation of the bumper spring main body which wraps around and bulges outward is limited by the contact of the restraining ring with the head.

Therefore, in such a bumper spring, the bumper spring body bulges outward when a large load is input by the restraint ring, even if the restraint ring is assembled in a non-bonded manner or if the bond is not sufficient. Since deformation can be effectively regulated, improvement in manufacturability and cost performance can be advantageously achieved while ensuring the required non-linear spring characteristics (load-deflection characteristics). If the bumper spring body is assembled in a non-bonded manner, a troublesome bonding process is unnecessary, and a dramatic improvement in manufacturability and cost performance can be achieved.

In addition, in such a bumper spring, since the outward bulging deformation of the bumper spring body is restricted by the head of the restraining ring when a large load is input, a sufficiently hard spring characteristic is exhibited. Even if the spring characteristic of the bumper spring body is set to be soft, overstroke can be advantageously prevented, and the spring characteristic in the low load range can be sufficiently softened to obtain a non-linear load-deflection characteristic more advantageously. It becomes.

Further, in such a bumper spring, the outward bulging deformation of the bumper spring main body at the time of inputting a large load is limited by the head of the restraint ring, so that the spring is made high at the time of inputting a large load. Therefore, it is not necessary to increase the axial dimension of the leg of the restraint ring so much that the volume of the bumper spring body is not significantly reduced by the placement of the restraint ring, and the bumper spring body is not enlarged. However, there is also an advantage that a soft spring characteristic and a large deformation stroke can be advantageously secured when a low load is input.

Further, in such a bumper spring, since the leg portion for locking the restraining ring to the bumper spring body is arranged so as to enter the inside of the bumper spring body by fitting into the concave groove, Inward bulging deformation of the bumper spring body at the time of a large load input can be effectively reduced or prevented, and buckling deformation due to such inward bulging deformation can be effectively prevented. Problems such as a decrease in durability due to can be advantageously avoided.

Further, in the bumper spring according to the first preferred aspect of the present invention, the spring portion can be further reduced in the small load region by the curled portion, and
The bump deformation of the bumper spring body from both axial sides of the head portion of the restraint ring can be advantageously suppressed, and the high spring characteristics can be stabilized and the durability can be improved in the large load range.

Furthermore, in the bumper spring according to the second preferred embodiment of the present invention, lower springs in a small load range and stabilization of high spring characteristics in a large load range can be achieved more advantageously. You will get it.

Further, in the bumper spring according to the third preferred embodiment of the present invention, the buckling bulging deformation of the bumper spring main body inward in the direction perpendicular to the axis at the time of inputting a large load is more advantageous. It can be prevented, and stable performance and excellent durability can be advantageously exhibited.

Furthermore, in the bumper spring according to the fourth preferred aspect of the present invention, the deformation of the bumper spring body can be more advantageously restricted by the restraint ring, and the restraint ring and the bumper spring body when a load is input. There is no problem with the contact sound of.

In the bumper spring according to the fifth preferred aspect of the present invention, the soft spring characteristic of the lower cylindrical portion is exhibited when a small load is input, and the hard spring characteristic of the upper cylindrical portion is input when a large load is input. Is exerted, non-linear load-deflection characteristics can be more advantageously realized, and in addition to the bellows-shaped lower cylindrical portion, a restraint ring is provided near the boundary between the upper and lower cylindrical portions. Since it is mounted, the occurrence of wrinkles and the like due to buckling deformation at the time of inputting a large load can be prevented, and excellent durability can be exhibited.

[0023]

EXAMPLES Examples of the present invention will now be described in detail with reference to the drawings in order to clarify the present invention more specifically.

First, FIGS. 1 and 2 show a bumper spring 10 as an embodiment of the present invention. The bumper spring 10 includes a bumper spring main body 14 having an insertion hole 12 extending through the central axis and having a substantially cylindrical shape as a whole, and the bumper spring main body 1
4 and a restraining ring 16 having a substantially annular shape attached to the outer peripheral surface of the intermediate portion in the axial direction. Then, as shown in FIG. 3, a suspension insulator 22 externally attached to the piston rod 20 of the shock absorber 18 in the insertion hole 12 to support the piston rod 20 on the vehicle body side in a vibration-proof manner, and a shock absorber 18 of the shock absorber 18. By being positioned between the shock absorber 18 and the cylinder 24, the shock absorber 18 is axially compressed and deformed between the suspension insulator 22 and the cylinder 24 when the shock absorber 18 operates.
The operating stroke of the is elastically limited.

More specifically, the bumper spring body 14
Is an upper cylindrical portion 2 having a substantially straight thick cylindrical shape.
6, a lower cylindrical portion 28 having a thin-walled cylindrical shape bent in a bellows shape, and an intermediate cylindrical portion 30 having a medium-walled cylindrical shape located between the upper cylindrical portion 26 and the lower cylindrical portion 28. It is configured and integrally molded with a rubber elastic body.

The bumper spring body 14
Is provided with a plurality of inward projections 32 extending in the axial direction on the inner circumferential surface of the opening of the insertion hole 12 on the side of the upper cylindrical portion 26, and these inward projections 32 cause the shock absorber 18 to It is adapted to be fitted into a fitting portion 34 formed on the piston rod 20 (see FIG. 3). Further, on the axial end surface on the side of the upper cylindrical portion 26, an annular circumferential groove 36 that functions as an air vent passage to the suspension insulator 22 (see FIG. 3) side, a positioning recess, and the like.
And a plurality of radial grooves 38 extending radially are formed.

Further, the intermediate cylindrical portion 30 is formed with a groove 40 having a substantially rectangular cross-section which is located at a central portion in the axial direction and which extends continuously in the circumferential direction, with an opening on the outer peripheral surface. Furthermore, on both sides sandwiching the groove 40 in the axial direction, the intermediate cylindrical portion 30 and the upper cylindrical portion 26 and the lower cylindrical portion 28 located on both axial sides thereof are located at the respective boundary portions, and are substantially A pair of curled portions 42 and 44, which have a V-shaped cross section and open to the outer peripheral surface and extend continuously in the circumferential direction, are formed.

Furthermore, in the lower cylindrical portion 28, the outer peripheral surface at the end in the axial direction is a tapered tapered surface 46, and
An annular peripheral groove 48 that continuously extends in the circumferential direction is formed on the inner peripheral surface located between the currant portion 44 and the tapered surface 46. Then, these cursed portion 44 and tapered surface 46
Further, the peripheral groove 48 forms a bent bellows shape.

On the other hand, the restraining ring 16 has a ring-shaped leg portion 50 and a ring-shaped head portion 52 which projects from the outer peripheral edge portion of the leg portion 50 on both axial sides by a predetermined length. The bumper spring body 14 is made of a material having higher rigidity than at least the bumper spring body 14. The leg portion 50 has a cross-sectional shape substantially corresponding to the recessed groove 40 formed in the intermediate cylindrical portion 30 of the bumper spring body 14, and the head portion 52 has an outer diameter dimension of the intermediate cylindrical portion 30. Has an inner diameter substantially corresponding to.

The restraint ring 16 is attached to the bumper spring body 14 by fitting the leg portion 50 into the groove 40 and locking the leg portion 50. The outer peripheral surface of the portion 50 is in close contact with the inner peripheral surface of the concave groove 40, and the inner peripheral surface of the head portion 52 is in close contact with the outer peripheral surface of the intermediate cylindrical portion 30 of the bumper spring body 14. Further, in the present embodiment, the axial length between the pair of curled portions 42 and 44 in the intermediate cylindrical portion 30 is substantially the same as the axial length of the head portion 52 of the restraining ring 16, and each curled portion 42. The opening edge portions on the inner side in the axial direction (on the side of the concave groove 40) of the shafts 44, 44 are closely attached to the inner peripheral surface of the head portion 52 of the restraining ring 16.

The binding of the restraint ring 16 to the bumper spring body 14 is performed by forming the restraint ring 16 and the bumper spring body 14 separately and then deforming the bumper spring body 14 to externally attach the restraint ring 16. It is also possible to assemble them by dividing the restraining ring 16 in the circumferential direction from the outside in the direction perpendicular to the axis of the bumper spring body 14, and then to assemble them by welding or the like. However, preferably, the preformed restraint ring 16 is installed in the molding die of the bumper spring body 14, and the rubber material is filled into the molding die to vulcanize and form the bumper spring body 14. It will be assembled at the same time as the bumper spring body 14 is molded. On the contrary, the pre-formed bumper spring body 14 is installed in the mold of the restraint ring 16 and the restraint ring 16 is formed by filling the mold with a material such as resin. It is also possible to assemble the ring 16 to the bumper spring body 14 simultaneously with its formation.

When assembling the restraint ring 16 to the bumper spring body 14, it is not necessary to perform a special bonding process. In this embodiment, the restraint ring 16 is attached to the bumper spring body 14. It is assembled in a non-bonded state.

Further, here, the depth at which the leg portion 50 of the restraint ring 16 enters the intermediate cylindrical portion 30 of the bumper spring main body 14, in other words, the leg portion 50 or the concave groove 4 is formed.
The radial dimension of 0: t is not particularly limited,
It is desirable to set (t / D) = 0.4 to 0.8 with respect to the thickness dimension D of the intermediate cylindrical portion 30 to which the restraint ring 16 is attached. If the value of t / D is too small, when the large load is input to the bumper spring 10, the intermediate cylindrical portion 30 is likely to be deformed inward in the radial direction, resulting in a buckling phenomenon or a piston rod of the shock absorber 18. This is because a problem such as interference with 20 may be caused. On the other hand, if the value of t / D is too large, the thickness of the intermediate cylindrical portion 30 becomes too thin, and it is difficult to secure sufficient durability. This is because there is a risk that

The axial length L of the head portion 52 of the restraint ring 16 and the axial projection length from the leg portion 50 are not particularly limited, and the material of the bumper spring body 14 (spring characteristic). It will be appropriately determined depending on the characteristics required for the bumper spring and the like.

In the bumper spring 10 having the above-described structure, when a small load is input, the soft spring characteristic can be advantageously exhibited due to the elastic deformation of the lower cylindrical portion 28, and the load gradually increases. As a result, the lower cylindrical portion 28 is axially crushed and the intermediate cylindrical portion 30 and the upper cylindrical portion 26 are elastically deformed. There, since the outward bulging deformation of the intermediate cylindrical portion 30 is limited by the head portion 52 of the restraining ring 16, when the deformation amount is relatively small, a soft spring characteristic is exhibited. As the amount of deformation increases, the spring characteristics rapidly harden. Therefore, the bumper spring 10 as a whole has a non-linear load-deflection characteristic, so that a good ride comfort and steering stability of the vehicle can be highly compatible.

Further, since the head portion 52 of the restraint ring 16 extends from both sides of the leg portion 50 in the axial direction, the leg portion 50 is not adhered to the bumper spring main body 14, which is caused. Even if the bumper spring body 14 is deformed so as to wrap around the legs 50 from both sides in the axial direction,
2 can be effectively suppressed, and a hard spring characteristic can be stably exhibited even when a large load is input so that the bumper spring main body 14 is almost completely crushed (for example, when a load of 1600 kg in a bumper spring for a passenger car is input). Along with
Interference with other members such as the dust cover can be advantageously prevented.

As the axial projection length of the head portion 52 from the leg portion 50 is increased, the deformation of the bumper spring main body 14 at the time of inputting a large load is further restricted and a hard spring characteristic is exhibited. Therefore, there is also an advantage that the characteristics of the bumper spring 10 can be easily tuned depending on the size of the head portion 52.

Further, since the head portion 52 of the restraint ring 16 limits the amount of deformation of the bumper spring body 14 when a large load is input, overstroke and interference with other members when a large load is input are avoided. It is possible to set the spring characteristic of the bumper spring body 14 itself to be soft, whereby the spring characteristic at the time of low load input can be further softened, and the non-linearity of the load-deflection characteristic of the bumper spring 10 can be further strengthened. It is also possible.

Further, the bumper spring 10 of the present embodiment.
In the above, since the cursed portions 42, 44 are formed on both sides in the axial direction with the restraint ring 16 sandwiched therebetween, the curled portions 42, 44 can more effectively exhibit the soft spring characteristic at the time of low load input. Further, outward bulging deformation of the bumper spring body 14 that wraps around both sides of the restraining ring 16 in the axial direction can be more effectively prevented, and a hard spring characteristic can be stably exhibited when a large load is input. .

Moreover, the bumper spring 10 of this embodiment is
In the above, since the bellows-shaped lower cylindrical portion 28 is provided, the spring characteristic at the time of inputting a low load can be tuned sufficiently softly, and the non-linearity of the load-deflection characteristic can be further strengthened.

Incidentally, FIG. 4 shows the results of actual measurement of the load-deflection characteristics of the bumper spring 10 having the above structure. In the bumper spring 10 used for such measurement, a rubber material (Hs = Hs =
75), and 6-6 nylon was used as the material of the restraint ring 16.

From the results shown in FIG. 4 also, the load-deflection characteristic excellent in non-linearity is recognized.

Although one embodiment of the present invention has been described above in detail, this is a literal example and the present invention is not construed as being limited to such a specific example.

For example, the cursed portions 42 and 44 in the bumper spring body 14 do not necessarily have to be provided.
Further, even when such a curled portion is formed, as in the bumper spring 60 shown in FIGS. 5 and 6, one or both of the curled portions 42, 44 has an opening edge portion which is the head of the restraining ring 16. It is also possible to form it so as to be located away from the portion 52, or to use a curled portion having a cross-sectional shape other than the V-shaped cross section as illustrated, such as a semicircle or U shape. In addition, in FIGS. 5 and 6, in order to facilitate the understanding thereof, the same reference numerals as those in the first embodiment are used in the drawings for the members and parts having the same structures as those in the first embodiment. Attach.

The concrete shape of the bumper spring body is not limited to that of the above-mentioned embodiment. For example, the bumper spring body may have a bellows shape over the entire length in the axial direction or a straight tube having no bellows-like portion. It can be shaped.

Further, the mounting position of the restraint ring with respect to the bumper spring body is not limited to the central portion in the axial direction, and can be appropriately determined in consideration of the shape and characteristics of the bumper spring body.

Further, the cross-sectional shape of the leg portion 50 of the restraint ring 16 is not limited to that of the above-mentioned embodiment, but the wedge-shaped cross section or the inverted wedge-shaped cross section whose thickness becomes smaller as it goes radially inward, Alternatively, a semicircular cross section or the like can be adopted.
However, the bumper spring body 14 when a large load is input
In order to suppress the bulging deformation inward or outward in the direction perpendicular to the axis, the rectangular cross-sectional shape as illustrated is desirable. Instead of providing the leg portion on the restraint ring 16, it is also conceivable to provide a locking protrusion projecting outward from the bumper spring body 14 to lock the head portion 52 of the restraint ring 16, but such a leg is not possible. If a restraint ring having no portion is adopted, buckling deformation of the bumper spring main body inwardly tends to occur when a large load is input, which causes a problem in durability and the like, which is not preferable.

Further, the mounting structure of the bumper spring to the vehicle is not limited to the external fitting and fixing of the shock absorber 18 to the piston rod 20 as shown in the example, and the shock absorber 18 is not limited to the external fitting and fixing. It is sufficient that an axial compressive force is exerted on the bumper spring between the cylinder and the member on the vehicle body side or the wheel side to which the piston rod of the shock absorber is attached, and various attachment structures are possible. Can be adopted. Specifically, for example, as shown in FIG. 7, the bumper spring body 14 is connected to the piston rod 2
Housing 54 of the suspension insulator 22 which is mounted on the vehicle body side so as to elastically connect and support the piston rod 20 to the vehicle body.
A mounting member 56 having a substantially shallow inverted cup shape is fixed to the lower surface of the above, and the axial end of the bumper spring body 14 on the upper cylindrical portion 26 side is fitted and fixed to the mounting member 56 to be mounted. Is also possible. A flange portion 58 that extends outward in the radial direction is provided on the peripheral edge of the opening of the mounting bracket 56.
8, a tubular bellows cover can be attached. In addition to the specific example shown in FIG. 7, a state in which the upper cylindrical portion 56 of the bumper spring body 14 is fixed to the cylinder side of the shock absorber 18 and the lower cylindrical portion 28 projects toward the suspension insulator 22 side. In the case of the inverted suspension structure in which the cylinder of the shock absorber 18 is mounted on the vehicle body side, the bumper spring body 14 can be attached to the wheel side member such as the suspension arm to which the piston rod is mounted. It is also possible to attach by fixing.

Although not listed one by one, the present invention can be carried out in variously modified, modified, improved, etc. modes based on the knowledge of those skilled in the art. It goes without saying that all of them are included in the scope of the present invention without departing from the spirit of the present invention.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a bumper spring as one embodiment of the present invention, which is a view corresponding to the I-I cross section in FIG.

FIG. 2 is a plan view of the bumper spring shown in FIG.

FIG. 3 is an explanatory diagram showing a mounted state of the bumper spring shown in FIG.

FIG. 4 is a graph showing measured data of load-deflection characteristics in the bumper spring having the structure shown in FIG.

5 is a vertical cross-sectional view showing a bumper spring as another embodiment of the present invention, which is a view corresponding to the VV cross section in FIG. 6. FIG.

6 is a plan view of the bumper spring shown in FIG.

FIG. 7 is a vertical cross-sectional explanatory view showing a specific example of another mounting structure of the bumper spring having the structure according to the present invention.

[Explanation of symbols]

 10,60 Bumper spring 14 Bumper spring body 16 Restraint ring 18 Shock absorber 40 Recessed groove 42,44 Curled part 50 Leg part 52 Head

Claims (2)

[Claims] 1. A bumper spring externally arranged on a piston rod of a shock absorber constituting a vehicle suspension for elastically limiting an operation stroke of the shock absorber, wherein the tubular bumper spring is formed of an elastic body. The outer peripheral surface of the main body is provided with a recessed groove that extends in an axially intermediate portion in the circumferential direction, while the leg portion is fitted and locked in the recessed groove, and an axial direction of the recessed groove from the outer peripheral portion of the leg portion. A bumper spring, characterized in that a restraining ring is provided which extends to both sides and has a head portion that is positioned to face the outer peripheral surface of the bumper spring body in the direction perpendicular to the axis. 2. The bumper spring main body is provided with a curling portion extending in the circumferential direction on both sides in the axial direction sandwiching the concave groove, and the opening edge portion of each of the curving portions on the concave groove side is provided. The bumper spring according to claim 1, wherein the bumper spring is positioned so as to face the inner peripheral surface of the head portion of the restraint ring.