JP6510872B2 - Buffer stopper - Google Patents

Description

  The present invention relates to a buffer stopper mounted as a buffer on an end of a steering rack of, for example, a steering apparatus of a vehicle.

  As is well known, when a driver rotates a steering wheel, a steering rack is moved through a pinion gear, and a steering rack of an automobile is moved through both left and right ends via ball joints. The connected tie rods are pivoted relative to the steering rack to pivot the wheels in any direction. In this type of steering apparatus, a buffer stopper is provided at the end of the steering rack as a buffer means for absorbing an impact with the end face of the rack housing.

  FIG. 8 shows a prior art shock absorbing stopper mounted, where reference numeral 200 indicates a rack housing, reference numeral 300 indicates a steering rack axially reciprocated through the rack housing 200, and reference numeral 400 indicates a rack. It is a tie rod connected via a ball joint 401 to a rack end 301 provided at the end of the steering rack 300. The buffer stopper 100 is attached to a surface of the rack end 301 opposite to the end face 201 a of the enlarged diameter portion 201 of the rack housing 200, and the stopper body 101 made of metal ring or the like, and rubber elastic material (rubber material Or a synthetic resin material having a rubber-like elasticity). The axial length of the buffer 102 is longer than the axial length of the cylindrical portion 101 a of the stopper body 101.

  For example, in a vehicle in which the steering force is assisted by hydraulic pressure, electric power, or the like, the shock absorber stopper 100 has a steering rack 300 that axially reciprocates with respect to the rack housing 200 when the steering wheel is vigorously turned to full lock. In the process of reaching the stroke end, the end 102 a of the buffer 102 is first brought into pressure contact with the end face 201 a of the rack housing 200 and compressed and deformed in the axial direction to reduce the impact. When the end portion of the cover contacts the end face 201a of the rack housing 200, it functions as a mechanical stopper that regulates the maximum displacement of the steering rack 300 (see, for example, Patent Document 1).

JP-A-8-133102

  In this type of buffer stopper, kinetic energy is efficiently absorbed within the range of stroke from the start of compression of the buffer body 102 to the end of the cylindrical portion 101a of the stopper body 101 coming into contact with the end face 201a of the rack housing 200. There is a need to. For this reason, a rubber elastic body is generally used as the buffer 102, and the spring characteristics and damping characteristics of the rubber elastic body are used, but the kinetic energy is absorbed as compared to those using the viscous fluid damping function. Low efficiency.

  In addition, there are also those that try to improve the absorption efficiency of kinetic energy utilizing the frictional resistance of rubber elastic body, but the absorption of kinetic energy not only in the direction that requires shock absorption, but also in the opposite direction. Since the frictional resistance is generated, there is a problem that the movement in the return direction by the compression reaction force of the rubber elastic body is inhibited.

  The present invention has been made in view of the above-described points, and the technical problem thereof is a buffer stopper capable of improving the absorption function of kinetic energy without inhibiting the movement in the return direction. To provide.

The buffer stopper according to the present invention is
In the axial direction by relative movement relatively movable disposed in one member of two members to be toward and away from the end face of each other, a stopper body having an end which end face facing the other member of said two members A first shock absorber made of a rubber-like elastic material disposed between the end faces of the two members, and the stopper body axially aligned in series with the first shock absorber at a position on the end face side of the other member ; and a second cushioning member made of a rubber-like elastic material incorporated, the first buffer body is the above lower spring than second cushioning body, said second cushioning body by the proximity of the end faces of the two members receiving an axial compression through the bulging deformed outer peripheral surface is axially slidably in contact with the other member in the radial direction due to the compression, the second buffer body, an end of the stopper body axial direction toward the end surface of the other member than parts It extends as to protrude.

  That is, in the above configuration, in the process of relatively moving the two members in the axial direction of the first and second shock absorbers in the axial direction, the first shock absorber, which is a relatively low spring, undergoes axial compression first. Excellent shock absorption by low spring can be obtained. Then, the first buffer compresses and deforms in the radial direction along with axial compression, and the outer peripheral surface of the first buffer contacts the other member and slides in the axial direction to generate frictional resistance. In addition, when the outer peripheral surface of the first shock absorber comes into contact with the other member, the radial expansion deformation thereof is suppressed, and as a result, the axial compression is suppressed. The body will be subjected to axial compression. Then, even in the compression process of the second buffer, since the frictional resistance is continuously generated by the outer peripheral surface of the first buffer sliding in the axial direction with the other member, absorbable kinetic energy is increased, Furthermore, when the end of the stopper body contacts the end face of the other of the two members, the maximum displacement amount is regulated.

  Next, with the end of the stopper body in contact with the end face of the other member of the two members, in the process of relative axial movement of the two members in the extension direction of the first and second shock absorbers, relative Since the compression in the axial direction of the first buffer, which is a low spring, is released and the outer diameter thereof is reduced, the frictional resistance due to sliding with the other member is reduced, and a second spring, which is a relatively high spring The axial compression of the buffer is released. For this reason, the movement of the two members in the return direction is not hindered.

  According to the shock absorber according to the present invention, the absorption function of kinetic energy can be improved by the elasticity and frictional resistance of the rubber-like elastic material in the compression direction, and the frictional resistance is relaxed in the return direction. Smooth operation in the return direction.

It is sectional drawing of the no load state which shows the preferable embodiment of the buffer stopper which concerns on this invention. FIG. 5 is a characteristic diagram of a preferred embodiment of a shock absorber according to the present invention. It is a sectional view of the first compression state of the first buffer which shows the desirable embodiment of the buffer stopper concerning the present invention. It is sectional drawing of the compression start state of the 2nd buffer which shows the preferable embodiment of the buffer stopper which concerns on this invention. It is sectional drawing of the maximum displacement control state by the stopper main body which shows the preferable embodiment of the buffer stopper which concerns on this invention. It is sectional drawing of the decompression process which shows the preferable embodiment of the buffer stopper which concerns on this invention. It is sectional drawing of the no load state which shows the other preferable embodiment of the buffer stopper which concerns on this invention. It is sectional drawing which shows an example of the buffer stopper by a prior art.

  Hereinafter, preferred embodiments of a shock absorber according to the present invention will be described with reference to the drawings.

FIG. 1 shows the shock absorbing stopper according to the present invention in a mounted state, and reference numeral 2 is a rack housing, reference numeral 3 is a steering rack axially reciprocated through the rack housing 2, and reference numeral 4 is a reference rack. It is a tie rod connected via a ball joint 41 to a rack end 31 provided at the end of the steering rack 3. At the end of the rack housing 2, the end portion 31 a of the rack end 31 opposite to the end surface 31 a opposite to the tie rod 4 and the enlarged diameter portion 21 axially facing from the outside diameter portion extend toward the tie rod 4 side A large diameter cylindrical portion 22 is formed. The steering rack 3 corresponds to one of the two members, and the rack housing 2 corresponds to the other of the two members.

  The buffer stopper 1 according to the present invention is externally inserted in the rack housing 2 and attached to the end surface 31 a of the rack end 31 opposite to the end surface 31 a of the rack end 31. The first buffer 12 and the second buffer 13 are incorporated in a side-by-side manner.

  The stopper main body 11 is made of metal or the like, and is expanded from the end of the cylindrical portion 11a externally inserted into the steering rack 3 to the outer diameter side from the end of the cylindrical portion 11a. It consists of the collar part 11b contact | abutted to the end surface 31a of the side.

  The first shock absorber 12 and the second shock absorber 13 are molded of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity), and are extrapolated to the cylindrical portion 11 a of the stopper main body 11 ing. The first buffer 12 is lower in rigidity than the second buffer 13, that is, has a lower spring than the second buffer 13. It is preferable that the spring constants of the first shock absorber 12 and the second shock absorber 13 be separated as far as possible, for example, the spring constant of the first shock absorber 12 be 1/10 or less of the spring constant of the second shock absorber 13 .

  The first buffer body 12 is bonded to the end face of the flange 11 b of the stopper main body 11 opposite to the rack end 31, and the outer diameter thereof is usually from the inner peripheral surface 22 a of the cylindrical portion 22 in the rack housing 2. Although small in diameter (non-contact), the outer peripheral surface 12a is brought into axial sliding contact with the inner peripheral surface 22a of the cylindrical portion 22 of the rack housing 2 by radial expansion deformation accompanied by axial compression, The axial thickness, the outer diameter dimension and the like are set.

  The second shock absorber 13 is located on the opposite side of the flange 11 b of the stopper body 11 as viewed from the first shock absorber 12, that is, on the side of the enlarged diameter portion 21 of the rack housing 2. The end portion of the stopper main body 11 opposite to the first buffer body 12 is extended from the end of the cylindrical portion 11 a of the stopper main body 11 in the diameter-increased portion 21 of the rack housing 2. It extends so as to project in the axial direction toward the end face 21a side of the lens.

  According to the buffer stopper 1 configured as described above, for example, in a vehicle in which the steering force is assisted by hydraulic pressure, electric power, or the like, when the steering wheel is vigorously turned to the full lock, the axial direction with respect to the rack housing 2 If the end face 13a of the second buffer 13 is pressed against the end face 21a of the enlarged diameter portion 21 of the rack housing 2 in the process of the reciprocating steering rack 3 reaching its stroke end, compared with the second buffer 13 The first buffer 12, which has a significantly lower spring constant, is subjected to axial compression prior to the second buffer 13. For this reason, in the initial stage of compression, as in the region a shown by the characteristic line in FIG. 2, excellent shock absorption due to the low spring characteristic is obtained.

  Here, since the first buffer body 12 is expanded and deformed in the radial direction as it is subjected to axial compression, the outer peripheral surface 12 a eventually becomes an inner portion of the cylindrical portion 22 in the rack housing 2 as shown in FIG. 3. The outer circumferential surface 12a of the first shock absorber 12 slides in the axial direction with the inner circumferential surface 22a of the cylindrical portion 22 with axial displacement of the steering rack 3 to generate frictional resistance. .

  Further, the amount of expansion deformation of the first buffer 12, and hence the amount of axial compression, is determined by the size of the gap on the outer peripheral side of the first buffer 12, that is, the first buffer 12 fills the gap on the outer peripheral side. As compression in the axial direction of the first buffer 12 is suppressed when the pressure reaches the limit, after that (after the displacement amount δ2 shown in FIG. 2 is reached), as shown in FIG. Two buffers 13 undergo axial compression.

  For this reason, the frictional resistance generated when the outer peripheral surface 12a of the first shock absorber 12 slides in the axial direction with the inner peripheral surface 22a of the cylindrical portion 22 is cylindrical as shown by the characteristic line r in FIG. From the contact time point δ1 with the inner circumferential surface 22a of the part 22, it rises largely at the initial stage of pressure contact, but thereafter becomes almost constant regardless of the displacement amount, while the reaction force against axial compression of the second shock absorber 13 2 increases in a non-linear manner, so the sum of the frictional resistance by the first buffer 12 and the compression reaction force by the second buffer 13 is, as in the region b in the characteristic line of FIG. After the displacement amount δ 2 is rapidly increased, as in the region c, the slope becomes smaller than the region b and nonlinearly increases.

  Then, as shown in FIG. 5, when the end of the cylindrical portion 11 a of the stopper main body 11 comes in contact with the end face 21 a of the enlarged diameter portion 21 of the rack housing 2, the steering rack 3 further moves in the compression direction of the second buffer 13. It can not be displaced, that is, it functions as a mechanical stopper which regulates the maximum displacement amount δ3 in the characteristic line of FIG. The impact at this time is effectively alleviated by the frictional resistance of the first buffer 12 and the compression reaction force of the second buffer 13.

  Next, in the process of moving the steering rack 3 relative to the rack housing 2 in the extension direction of the first buffer 12 and the second buffer 13 from the state shown in FIG. 5, as shown in FIG. Since the expansion of the body 13 causes a delay due to hysteresis, the compression state of the first buffer 12, which is a low spring, is relieved and the outer diameter thereof is reduced, that is, the outer peripheral surface 12a of the first buffer 12 is a rack housing 2 so as to move away from the inner circumferential surface 22 a of the cylindrical portion 22. For this reason, since the frictional resistance due to the sliding of the first buffer 12 disappears and the axial compression of the second buffer 13 is released in that state, the compression process is carried out as in the region d in the characteristic line of FIG. The load is reduced by the amount that does not generate frictional resistance compared to the area c in.

  Therefore, according to the illustrated embodiment, at the time of displacement of the first shock absorber 12 and the second shock absorber 13 in the compression direction, the initial stage of displacement is a low spring, and thereafter the frictional resistance of the first shock absorber 12 and the A large amount of kinetic energy can be absorbed by the compression reaction force of the second buffer 13, and in the unloading stroke, it is possible to eliminate the frictional resistance and ensure a smooth return operation of the steering rack 3.

  Moreover, even if the outer peripheral surface 12 a of the first shock absorber 12 wears over time due to the sliding with the inner peripheral surface 22 a of the cylindrical portion 22 in the rack housing 2, as described above, the first shock absorber 12 The bulging deformation due to the axial compression force is performed until the gap on the outer peripheral side is completely filled, so that it is possible to stably obtain friction damping by sliding with the inner peripheral surface 22a of the cylindrical portion 22 for a long period of time .

  As in the other embodiment shown in FIG. 7, only the second buffer body 13 is extrapolated to the cylindrical portion 11 a of the stopper body 11, and the first buffer body 12 is a rack at the flange portion 11 b of the stopper body 11. The first buffer body 12 may be compressed between the flange portion 11 b of the stopper main body 11 and the rack end 31 by adhering to the surface facing the end 31.

DESCRIPTION OF SYMBOLS 1 Buffering stopper 11 Stopper main body 12 1st buffer 13 13 2nd buffer 2 rack housing (the other member of two members)
3 Steering rack (one of the two members)

Claims (1)

In the axial direction by relative movement relatively movable disposed in one member of two members to be toward and away from the end face of each other, a stopper body having an end which end face facing the other member of said two members ,
A first shock absorber made of a rubber-like elastic material disposed between the end faces of the two members ;
A second shock absorber made of a rubber-like elastic material, which is incorporated in the stopper main body in axial series with the first shock absorber at a position on the end face side of the other member ;
Equipped with
The first shock absorber is a lower spring than the second shock absorber, and is axially compressed via the second shock absorber by the proximity of the end faces of the two members, and is expanded in the radial direction along with the compression. Bringing the circumferentially deformed outer circumferential surface into axial contact with the other member ,
The buffer stopper second cushioning member is characterized in that the Ru Tei extending to the stopper than the end of the body protruding toward the end surface of the other member in the axial direction.

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