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EP-4331947-B1 - DIRECT ACTION DAMPER AND STEERING DEVICE

EP4331947B1EP 4331947 B1EP4331947 B1EP 4331947B1EP-4331947-B1

Inventors

  • NAKAYA KAZUMASA
  • ENDO AKIFUMI

Dates

Publication Date
20260506
Application Date
20220224

Claims (10)

  1. A linear damper (120) comprising: an inner chamber forming body (121) formed in a tubular shape and having, inside a tubular portion, an inner chamber (125a, 125b) where fluid (126) is liquid-tightly housed; a relative displacement body (140) slidably fitted in the inner chamber forming body (121) and formed displaceable relative to the inner chamber forming body (121); and a flow control valve (127, 128) provided for at least one of the inner chamber forming body (121) or the relative displacement body (140) to allow the fluid (126) to flow while limiting a flow of the fluid (126), wherein the linear damper (120) is arranged between two attachment target objects linearly displaceable relative to each other to damp external force received due to relative displacement by limiting the flow of the fluid (126), characterized in that : the relative displacement body (140) has an attachment portion to be attached to one of the two attachment target objects, the inner chamber forming body (121) has a bumper portion (131) with which the other one of the two attachment target objects bumps, and the bumper portion (131) includes an elastic body elastically receiving bump of the other one of the two attachment target objects.
  2. The linear damper (120) according to claim 1, further comprising: a return elastic body (155) providing elastic force to at least one of the inner chamber forming body (121) or the relative displacement body (140) to elastically press the inner chamber forming body (121) or the relative displacement body (140) formed with no bumper portion (131) in a direction apart from the bumper portion (131).
  3. The linear damper (120) according to claim 1 or 2, wherein the bumper portion (131) is formed in an annular shape.
  4. The linear damper (120) according to any one of claims 1 to 3, wherein the bumper portion (131) is made of an elastomer material.
  5. The linear damper (120) according to claim 4, wherein the bumper portion (131) is formed with at least one of a bottomed hole (131c) or a through-hole (131a).
  6. The linear damper (120) according to any one of claims 1 to 5, wherein the inner chamber forming body (121) and the relative displacement body (140) each have displacement limit defining portions (144, 147) defining one and another displacement limits in an range of the relative displacement by bump by the relative displacement, and the displacement limit defining portion (144, 147) for at least one of the one displacement limit or the other displacement limit includes an elastic body.
  7. The linear damper (120) according to any one of claims 1 to 6, wherein the relative displacement body (140) includes a volume change compensation device (153) configured to compensate for a change in a volume of the fluid (126) in the inner chamber (125a, 125b).
  8. A steering device (100) including a steering shaft (102) formed so as to extend in a bar shape and configured to rotate by operation of a steering wheel (101); a rack bar (103) formed to extend in a bar shape to transmit a reciprocating motion, converted from a rotary motion of the steering shaft (102), in an axis direction; an intermediate coupling body (105) coupled to each end portion of the rack bar (103) and directly or indirectly coupling a wheel (112) targeted for steering to each end portion; and a rack housing (104) covering the rack bar (103), comprising: the linear damper (120) according to any one of claims 1 to 7, wherein the linear damper (120) is provided between the rack housing (104) and the rack bar (103) or the intermediate coupling body (105) to damp impact from the wheel (112) and/or impact due to inertial force from a side of the steering shaft (102).
  9. The steering device (100) according to claim 8, wherein the relative displacement body (140) is connected to the intermediate coupling body (105), and the inner chamber forming body (121) is formed so as to contact or separate from the rack housing (104) by the reciprocating motion of the rack bar (103).
  10. The steering device (100) according to claim 8, wherein the inner chamber forming body (121) is connected to an end portion of the rack housing (104), and the relative displacement body (140) is formed such that the rack bar (103) or the intermediate coupling body (105) penetrates therethrough and the rack bar (103) or the intermediate coupling body (105) contacts or separates from the relative displacement body (140) by the reciprocating motion of the rack bar (103).

Description

TECHNICAL FIELD The present invention relates to a linear damper configured to damp motion energy of linear motion and a steering device including the linear damper. BACKGROUND ART Typically, there has been a linear damper configured to damp motion energy of linear motion. For example, the inventor(s) of the present application has proposed a linear damper as described in Patent Literature 1 below. In this linear damper, an impact load caused between a rack end and a rack housing in a steering device of a self-propelled vehicle is reduced by damping force generated on the rack end displaceable relative to the rack housing by limiting the flow of fluid. CITATION LIST PATENT LITERATURE PATENT LITERATURE 1: Japanese Patent Application No. 2020-096430 JP H04 128978 U discloses a rack and pinion type steering apparatus in which a main body of a ball joint for connecting a rack and a tie rod is provided with a stopper on a steering rigid body side for slidably holding a rack. US 2009/194379 A1 discloses a fluid-pressure shock absorber. DE 10 2014 206756 A1 discloses a spring assembly for a vehicle. SUMMARY OF INVENTION However, the linear damper disclosed in Patent Literature 1 above has such a problem that when the rack end rapidly approaches the rack housing and the linear damper collides with the rack housing, great collision sound is caused and great impact is instantaneously applied to the steering device. The present invention has been made in order to cope with the above-described problem. An object of the present invention is to provide a linear damper capable of reducing great collision sound or impact even when a great load rapidly acts and a steering device including the linear damper. To achieve the aforementioned object, the present invention features a linear damper including: an inner chamber forming body formed in a tubular shape and having, inside a tubular portion, an inner chamber where fluid is liquid-tightly housed; a relative displacement body slidably fitted in the inner chamber forming body and formed displaceable relative to the inner chamber forming body; and a flow control valve provided for at least one of the inner chamber forming body or the relative displacement body to allow the fluid to flow while limiting a flow of the fluid, in which: the linear damper is arranged between two attachment target objects linearly displaceable relative to each other to damp external force received due to relative displacement by limiting the flow of the fluid; the relative displacement body has an attachment portion to be attached to one of the two attachment target objects; the inner chamber forming body has a bumper portion with which the other one of the two attachment target objects bumps; and the bumper portion includes an elastic body elastically receiving bump of the other one of the two attachment target objects. According to this configuration, in the linear damper, the bumper portion includes the elastic body. Thus, even in a case where the bumper portion collides with a portion of the attachment target object facing the bumper portion among the two attachment target objects for which the linear damper is provided and a great load rapidly acts thereon, great collision sound or impact can be reduced. Another aspect of the present invention is that the linear damper further includes a return elastic body providing elastic force to at least one of the inner chamber forming body or the relative displacement body to elastically press the inner chamber forming body or the relative displacement body formed with no bumper portion in a direction apart from the bumper portion. According to this configuration, in the linear damper, the return elastic body provides elastic force to the inner chamber forming body or the relative displacement body formed with no bumper portion, and accordingly, elastically displace the inner chamber forming body or the relative displacement body in the direction apart from the bumper portion. Thus, in the linear damper according to the present invention, in a case where no external force of displacing the inner chamber forming body and the relative displacement body relative to each other acts, the inner chamber forming body or the relative displacement body formed with no bumper portion is constantly positioned at an end portion on the side apart from the bumper portion in a relative displacement area, i.e., an operation start position for fulfilling the damping function of the flow control valve, so that the stroke of the relative displacement body can be maximized. Still another feature of the present invention is the linear damper in which the bumper portion is formed in an annular shape. According to this configuration, in the linear damper, the bumper portion is formed in the annular shape. Thus, the entirety or part of at least one of the two attachment target objects for which a component of the linear damper or the linear damper is provided can be arranged insi