JP6479495B2 - Buffer stopper - Google Patents

Description

  The present invention relates to a buffer stopper attached as a buffer means to an end portion of a steering rack in a vehicle steering apparatus, for example.

  As is well known, an automobile rack-and-pinion type steering device is such that when a driver rotates a steering wheel, the steering rack is moved via pinion gears, and ball joints are provided at both left and right ends thereof. The tie rods connected to each other are swung with respect to the steering rack so as to turn the wheel in an arbitrary direction. In this type of steering apparatus, a buffer stopper is provided at the end portion of the steering rack as a buffer means for reducing the impact with the end surface of the rack housing.

  4 is a partial cross-sectional view showing a state in which a buffer stopper according to the prior art is mounted, and FIG. 5 is a cross-sectional perspective view showing a single body. In FIG. 4, reference numeral 200 is a rack housing, reference numeral 300 is a steering rack inserted into the rack housing 200 so as to be reciprocally movable in the axial direction, and reference numeral 400 is a rack end 301 provided at an end of the steering rack 300. It is a tie rod connected via a ball joint 401. The buffer stopper 100 is attached to a surface of the rack end 301 that faces the end surface 201a of the enlarged diameter portion 201 of the rack housing 200, and as shown in FIG. Are provided with a shock absorber 102 integrally formed of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity). The shock absorber 102 has a protruding end portion 102 a that extends in the axial direction from the outer periphery of the cylindrical portion 101 a of the stopper main body 101 toward the end surface 201 a side of the enlarged diameter portion 201 of the rack housing 200.

  The buffer stopper 100 is provided with a steering rack 300 that reciprocates in the axial direction with respect to the rack housing 200 when, for example, the steering force is turned to full lock in a vehicle assisted by steering force by hydraulic pressure or electric power. In the process of reaching the stroke end, the projecting end portion 102a of the shock absorber 102 first collides with the end surface 201a of the rack housing 200 and is compressed and deformed to reduce the impact, and then the end of the cylindrical portion 101a of the stopper main body 101. When the portion comes into contact with the end surface 201a of the rack housing 200, it functions as a mechanical stopper that regulates the maximum amount of displacement of the steering rack 300 (see, for example, Patent Literature).

JP-A-8-133102

  Here, the buffering by the conventional buffer stopper 100 absorbs the kinetic energy due to the mass and moving speed of the steering rack 300 which is a movable body by the reaction force and displacement against the compression of the buffer body 102 made of a rubber-like elastic material. As shown in FIG. 6 where the vertical axis represents the reaction force and the horizontal axis represents the amount of displacement, the amount of energy that can be absorbed is a hatched region between the characteristic line of the buffer body 102 and the horizontal axis. It can be expressed as an area. Therefore, in order to increase the amount of energy that can be absorbed, the area of the hatched region in FIG. 6 is increased by increasing the maximum compression displacement amount of the buffer body 102 or increasing the reaction force (spring constant). It is common to do.

However, in this type of buffer stopper 100, the amount of compressive displacement of the buffer body 102 is regulated by a mechanical stopper (stopper body 101). When the force F _MAX is restricted, the maximum reaction force F _MAX at the maximum compression displacement becomes too large if the volume of the buffer body 102 is simply expanded or a rubber material having high hardness is used. Therefore, there is a problem that the amount of energy that can be absorbed by the buffer stopper 100 cannot be sufficiently increased.

  The present invention has been made in view of the above points, and its technical problem is to determine the amount of energy that can be absorbed without depending only on the maximum compression displacement amount of the buffer and the reaction force against compression. The object is to provide a buffer stopper which can be enlarged.

  As a means for effectively solving the technical problem described above, the buffer stopper according to the present invention is attached to one of the two members that are axially movable relative to each other and is formed on the other of the two members. An annular stopper body opposed to the stopper body, and an annular buffer body provided integrally with the stopper body, the buffer body is made of a rubber-like elastic material and faces the end face A projecting end portion extending in the axial direction from the end portion toward the end surface side, and a friction projection that is slidably contacted with a cylindrical surface formed on the other of the two members. .

  According to the above configuration, the protruding end portion of the shock absorber attached to one of the two members is formed on the other of the two members in the process in which the axial relative movement of the two members reaches the stroke end. While colliding with the end face, it is compressed and deformed, and the friction projection formed on this buffer body relieves the impact by the frictional resistance generated by sliding with the cylindrical surface formed on the other of the two members, Next, the maximum amount of displacement is regulated by the end of the stopper body coming into contact with the end face. For this reason, in addition to the reaction force against the compression of the shock absorber made of a rubber-like elastic material, a large reaction force can be obtained from the beginning of the compression displacement of the shock absorber due to the frictional resistance. Can be bigger.

  According to the buffer stopper of the present invention, the amount of energy that can be absorbed can be increased by the reaction force and the frictional resistance against the compression of the buffer without depending only on the maximum compression displacement amount and the spring constant of the buffer. .

It is a fragmentary sectional view which shows preferable embodiment of the buffer stopper which concerns on this invention in a mounting state. It is a section perspective view showing a desirable embodiment of a buffer stopper concerning the present invention. It is a characteristic line figure for demonstrating the effect | action by the buffer stopper which concerns on this invention. It is a fragmentary sectional view which shows an example of the buffer stopper by a prior art in a mounting state. It is a cross-sectional perspective view which shows an example of the buffer stopper by a prior art. It is a characteristic diagram of the buffer stopper by a prior art.

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

  FIG. 1 is a partial cross-sectional view showing a buffer stopper according to the present invention in a mounted state, and FIG. 2 is a cross-sectional perspective view showing a single body. In FIG. 1, reference numeral 2 is a rack housing, reference numeral 3 is a steering rack inserted in the rack housing 2 so as to be reciprocally movable in the axial direction, and reference numeral 4 is a rack end 31 provided at an end of the steering rack 3. This is a tie rod connected via a ball joint 41. At the end of the rack housing 2, the end portion 31 a of the rack end 31 opposite to the tie rod 4 in the axial direction is opposed to the enlarged diameter portion 21 and extends from the outer diameter portion toward the tie rod 4, and from the rack end 31. A large-diameter cylindrical portion 22 is formed. The steering rack 3 corresponds to one of the two members described in claim 1, and the rack housing 2 corresponds to the other of the two members described in claim 1.

  The buffer stopper 1 is disposed in contact with the end surface 31a of the rack end 31 opposite to the tie rod 4, and as shown in FIG. 2, the stopper body 11 and the buffer body provided integrally with the stopper body 11 are provided. A body 12 is provided.

  The stopper main body 11 in the buffer stopper 1 is made of a metal ring or the like. The stopper 11 is externally inserted into the steering rack 3 and extends from the end of the cylindrical portion 11a to the outer diameter side. It consists of the collar part 11b contact | abutted by the end surface 31a on the opposite side to the tie rod 4.

  The buffer body 12 in the buffer stopper 1 is formed integrally with the stopper main body 11 with a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity), and is formed on the cylindrical portion 11 a of the stopper main body 11. It is bonded to the outer peripheral surface and the end surface of the flange portion 11b opposite to the rack end 31 and extends in the axial direction from the outer periphery of the cylindrical portion 11a of the stopper body 11 toward the end surface 21a side of the enlarged diameter portion 21 of the rack housing 2. A cylindrical portion of the rack housing 2 that is formed continuously or intermittently in the circumferential direction on the outer peripheral surface of the protruding end 12a and the end opposite to the protruding end 12a (near the flange 11b of the stopper main body 11). The friction projection 12b is slidably contacted with the inner peripheral surface 22a of the rim 22. The inner peripheral surface 22a of the cylindrical portion 22 corresponds to the cylindrical surface described in claim 1.

  According to the buffer stopper 1 configured as described above, for example, in a vehicle whose steering force is assisted by hydraulic pressure or electric power, when the steering wheel is turned to full lock, the axial direction with respect to the rack housing 2 is achieved. In the process in which the reciprocating steering rack 3 reaches its stroke end, the protruding end 12a of the shock absorber 12 first collides with the end surface 21a of the enlarged diameter portion 21 of the rack housing 2 and is compressed and deformed. The friction projections 12b formed on the cylinder 12 reduce the impact by generating a frictional resistance with the inner peripheral surface 22a of the cylindrical portion 22 of the rack housing 2, and the end of the cylindrical portion 11a of the stopper body 11 is then relieved. A mechanical stopper that regulates the maximum amount of displacement of the steering rack 3 by contacting the end surface 21a of the enlarged diameter portion 21 of the rack housing 2; To function Te.

  Here, the reaction force caused by the shock absorber 12 colliding with the end surface 21a of the enlarged diameter portion 21 of the rack housing 2 and being compressed and deformed linearly increases in the initial stage of compression as shown by the characteristic line A in FIG. However, when the amount of displacement increases to some extent, it increases nonlinearly. On the other hand, the reaction force due to the frictional resistance generated between the friction projection 12b and the inner peripheral surface 22a of the cylindrical portion 22 of the rack housing 2 is the initial compression displacement of the shock absorber 12 as shown by the characteristic line B in FIG. Rises largely as a static frictional force, and then decreases slightly as a dynamic frictional force when the friction projection 12b starts to slide on the inner peripheral surface 22a of the cylindrical portion 22 of the rack housing 2, but is constant regardless of the amount of displacement. A frictional force is generated.

For this reason, the reaction force due to the buffer 12 shown by the characteristic line C in FIG. 3 is the sum of the reaction force due to the compression reaction force and the frictional resistance. The area between the two lines (hatched area) corresponds to the sum of the area between the characteristic line A and the horizontal axis and the area between the characteristic line B and the horizontal axis. is there. Therefore, as in the prior art, by simply increasing the hardness (spring constant) of the rubber-like elastic material, the maximum reaction force F _MAX 1 at the time of the maximum compression displacement is changed to the reaction force and frictional resistance due to the compression deformation of the buffer body 12. According to the buffer stopper 1 of the present invention, as shown by the characteristic line C, the frictional resistance acts as compared with the characteristic line D when the maximum reaction force F _MAX2 is raised by the sum of the reaction forces of Since a large reaction force can be obtained from the beginning of the compression displacement of the shock absorber 12, the amount of energy that can be absorbed can be increased efficiently, and the shock absorbing performance can be improved.

Further, when the maximum reaction force F _MAX2 is too large, the problem can be avoided while suppressing a decrease in buffer performance by taking measures such as reducing the hardness (spring constant) of the rubber-like elastic material.

DESCRIPTION OF SYMBOLS 1 Buffer stopper 11 Stopper main body 12 Buffer body 12a Projection end part 12b Friction protrusion 2 Rack housing (The other of two members)
22a Inner peripheral surface (tubular surface)
3 Steering rack (one of two members)

Claims (1)

  An annular stopper body that is attached to one of the two members that are axially movable relative to each other and that faces the end surface formed on the other of the two members, and an annular buffer that is provided integrally with the stopper body The shock absorber is made of a rubber-like elastic material, and has a protruding end extending in the axial direction from the end of the stopper body facing the end surface toward the end surface, and the two members. A shock-absorbing stopper, characterized in that a friction protrusion is formed so as to be slidably contacted with a cylindrical surface formed on the other of them.

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