JP4442842B2 - Damper rebound stopper structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a damper rebound stopper structure.
[0002]
[Prior art]
A damper such as a hydraulic shock absorber for a vehicle has a piston rod inserted into the cylinder, has a rebound stopper made of rubber or the like on the outer periphery of the piston rod inside the cylinder, and is provided on the piston rod when the piston rod is fully extended. A rebound stopper is sandwiched between the rebound sheet and a rod guide provided in the cylinder to elastically compress and deform in the axial direction to absorb impact energy and reduce impact sound when fully extended.
[0003]
In such a damper, the rebound stopper that also deforms in the radial direction when fully extended contacts the inner periphery of the cylinder, so that the hydraulic oil flows into the closed chamber defined by the inner periphery of the cylinder and the rod guide at the upper part of the rebound stopper. When confined, this becomes an oil lock state, preventing the rebound stopper from bending with respect to the impact load and impairing the shock absorbing performance when fully extended.
[0004]
Therefore, in the prior art described in Japanese Patent Application Laid-Open No. 2000-120757, a notch groove extending in the axial direction is provided in a part of the circumferential direction of the outer periphery of the rebound stopper, and the notch groove is formed in the hydraulic oil. By functioning as an escape path, a closed chamber that causes an oil lock state is not formed at the top of the rebound stopper.
[0005]
[Problems to be solved by the invention]
However, in the prior art, in order to avoid the occurrence of an oil lock state accompanying the deformation of the rebound stopper, a notch groove is provided in the entire length of the outer periphery of the rebound stopper. This results in a thin portion of the meat, resulting in uneven thickness of the meat in the circumferential direction and poor durability.
[0006]
An object of the present invention is to avoid the occurrence of an oil lock state associated with deformation of a rebound stopper and improve the durability of the rebound stopper in a rebound stopper structure of a damper.
[0007]
[Means for Solving the Problems]
The invention of claim 1 has a piston rod inserted into the cylinder, and a rebound stopper is provided on the outer periphery of the piston rod inside the cylinder, and the rebound stopper is provided on the piston rod when the piston rod is fully extended, and the cylinder In the rebound stopper structure of the damper that is compressed and elastically deformed by being sandwiched between the rod guide and the inner periphery of the cylinder, and between the inner periphery of the rebound stopper and the outer periphery of the piston rod. An annular gap is provided, and a notch is provided on the upper end surface of the rebound stopper, a notch is provided on the lower end surface of the rebound stopper, and protrusions are provided at a plurality of circumferential positions on the inner periphery of the rebound stopper. An annular gap is formed by contacting the piston rod, and the rebound stop The upper and lower the Kino sectional area notch provided on the end face of the one in which was set to be larger than the cross-sectional area of the annular gap provided between the outer periphery of the piston rod.
[0010]
[Action]
(a) When the damper is fully extended , the rebound stopper is sandwiched from above and below between the rebound seat provided on the piston rod and the rod guide provided on the cylinder, and the rebound stopper is elastically compressed and deformed in the axial direction. When mitigating absorption and impact noise, the hydraulic oil at the top of the rebound stopper that deforms in the radial direction and contacts the inner circumference of the cylinder passes through the annular gap on the inner circumference from the notch on the upper face, and further on the lower face. Escape from the notch to the cylinder oil chamber, avoiding the occurrence of an oil lock. Thereby, the bending with respect to the impact load of the rebound stopper is not suppressed. In other words, the spring constant of the rebound stopper can be lowered, and the shock absorbing performance when fully extended can be improved.
[0011]
(b) As an escape route for hydraulic oil over the entire length of the rebound stopper, an annular gap is provided on the inner periphery of the rebound stopper, and the thickness of the meat is not made uneven in the circumferential direction, thereby improving durability. .
[0012]
(c) By providing notches on the upper and lower end faces of the rebound stopper, the resistance to compressive deformation at the initial stage of elongation can be reduced (softened).
[0013]
(d) When the same notch is provided on the upper and lower end faces of the rebound stopper, the direction of assembling to the piston rod is eliminated, and the assembling property can be improved.
[0014]
(e) Protrusions are provided at a plurality of positions in the circumferential direction on the inner periphery of the rebound stopper, and the rebound stopper can form the annular gap stably by bringing the protrusion into contact with the piston rod to form an annular gap.
[0015]
(f) The rebound stopper reduces the contact area with the piston rod only to the protrusion part compared to the one that contacts the outer periphery of the piston rod on the entire inner circumference, making it easier to lightly press into the piston rod. A stable mounting state that does not move up and down freely on the outer periphery of the piston rod can be easily formed.
[0016]
(g) The cross-sectional area A2 of the notch provided on the upper and lower end faces of the rebound stopper is made larger than the cross-sectional area A1 of the annular gap provided between the outer periphery of the piston rod. Therefore, the notch that becomes the escape route of the hydraulic oil from the upper part of the rebound stopper in the above (a) does not become a restriction, and the spring constant of the rebound stopper can be determined only by the spring characteristics of the constituent material of the rebound stopper, It is possible to stabilize the shock absorbing performance when fully extended.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
1 is a schematic cross-sectional view showing the main part of the damper, FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1, FIG. 3 is a rebound stopper, (A) is a cross-sectional view, (B) is an end view, FIG. 4 is a schematic cross-sectional view showing a compression deformation state of the rebound stopper, and FIG. 5 is a cross-sectional view showing a modification of the rebound stopper.
[0018]
1 and 2, the damper 10 is used as a vehicle hydraulic shock absorber, and includes a cylinder 11 connected to one of the axle side and the vehicle body side, and a piston rod 12 connected to the other side. The piston rod 12 is inserted into the cylinder 11 from a rod guide 13 provided in the cylinder 11 and can slide in the axial direction. The piston 11 (not shown) fixed to the insertion end moves the interior of the cylinder 11 into upper and lower oil chambers. 14 and 15 (not shown) are partitioned. The damper 10 is provided with an extension side flow path and a pressure side flow path connecting the upper and lower oil chambers 14 and 15 in the piston, and an impact received by the vehicle from the road surface by a damping mechanism configured by providing a damping valve in these flow paths. It is possible to control the expansion and contraction vibration of the suspension spring to absorb
[0019]
However, the damper 10 has a rebound stopper 20 mounted on the outer periphery of the piston rod 12 inside the cylinder 11, and the rebound seat 16 provided on the piston rod 12 and the rod provided on the cylinder 11 when the piston rod 12 is fully extended. The rebound stopper 20 is sandwiched between the guide 13 and elastically deformed in the axial direction to absorb the impact energy and alleviate the impact sound when fully extended (FIG. 4).
[0020]
The rebound stopper 20 is a long cylindrical body made of urethane rubber or the like, and its spring property is improved by arranging the large diameter portion 21 and the small diameter portion 22 alternately in the axial direction so as to form a bellows shape on the outer surface of the cylinder. I am trying.
[0021]
Further, as shown in FIG. 3, when the damper 10 is fully extended, the rebound stopper 20 is also deformed in the radial direction when the rebound stopper 20 is elastically compressed and deformed in the axial direction so as to absorb shock energy and shock noise. In order to prevent the hydraulic oil in the upper part of the rebound stopper 20 contacting the inner periphery of the cylinder 11 from being confined in this upper space and generating an oil lock state, an annular shape is formed between the inner periphery and the outer periphery of the piston rod 12. A clearance 23 is provided, and recesses 24A and 25A are provided on the upper and lower end surfaces, and the recesses are formed as notches 24 and 25, respectively. The recesses 24A and 25A may have a V-shaped cross section, a semicircular cross section, or the like in addition to a square cross section. In the present embodiment, each of the notches 24 and 25 is four, but may be any number of one or more. Further, the notches 24 to 25 are preferably arranged symmetrically in the circumferential direction between the adjacent notches 24 (25) (in this embodiment, 4 in the circumferential direction), but may be arbitrary. The annular gap 23 and the notches 24 and 25 are connected to each other to provide a hydraulic oil escape path from the upper space of the rebound stopper 20.
[0022]
At this time, the rebound stopper 20 is provided with protrusions 26 at a plurality of circumferential positions (in this embodiment, four equal positions) on the inner periphery, and the rebound stopper 20 causes the protrusions 26 to abut against the piston rod 12 to move the piston rod 12. And press-fitted to form an annular gap 23.
[0023]
Further, the rebound stopper 20 is configured such that the total cross-sectional area (flow path area) A2 of the notches 24 and 25 provided on the upper and lower end faces is equal to the cross-sectional area (flow path area) of the annular gap 23 between the outer periphery of the piston rod 12. ) It is set larger than A1.
[0024]
According to this embodiment, there are the following operations.
(1) When the damper 10 is fully extended, when the rebound stopper 20 is elastically compressed and deformed in the axial direction to absorb the impact energy and the shock noise, the rebound is also deformed in the radial direction and comes into contact with the inner periphery of the cylinder 11 The hydraulic oil at the top of the stopper 20 passes from the notch 24 at the upper end surface through the inner annular gap 23 and further escapes from the notch 25 at the lower end surface to the oil chamber 14 of the cylinder 11 to avoid the occurrence of an oil lock state. To do. Thereby, the bending with respect to the impact load of the rebound stopper 20 is not suppressed. In other words, the spring constant of the rebound stopper 20 can be lowered and the shock absorbing performance when fully extended can be improved.
[0025]
(2) As an escape route for the hydraulic oil over the entire length of the rebound stopper 20, an annular gap 23 is provided on the inner periphery of the rebound stopper 20, and the thickness of the meat is not made uneven in the circumferential direction. Can be improved.
[0026]
{Circle around (3)} By providing the notches 24 and 25 on the upper and lower end faces of the rebound stopper 20, it is possible to reduce (soften) the resistance to compressive deformation at the initial stretch.
[0027]
(4) When the same notches 24 and 25 are provided on the upper and lower end faces of the rebound stopper 20, the direction of assembling to the piston rod 12 is eliminated, and the assembling property can be improved.
[0028]
(5) Protrusions 26 are provided at a plurality of positions in the circumferential direction on the inner periphery of the rebound stopper 20, and the rebound stopper 20 makes the annular gap 23 stable by bringing the protrusions 26 into contact with the piston rod 12 to form an annular gap 23. Can be formed.
[0029]
(6) The rebound stopper 20 reduces the contact area with the piston rod 12 only to the portion of the protrusion 26 as compared with the one that contacts the outer periphery of the piston rod 12 on the entire inner periphery. Press fitting becomes easy, and a stable mounting state that does not move up and down freely on the outer periphery of the piston rod 12 can be easily formed.
[0030]
(7) The sectional area A2 of the notches 24, 25 provided on the upper and lower end faces of the rebound stopper 20 is made larger than the sectional area A1 of the annular gap 23 provided between the outer periphery of the piston rod 12. Therefore, the notches 24 and 25 that serve as escape routes of hydraulic oil from the upper part of the rebound stopper 20 in the above-mentioned (1) do not become a restriction, and the spring constant of the rebound stopper 20 is limited only to the spring characteristics of the constituent material of the rebound stopper 20. It is possible to stabilize the shock absorbing performance when fully extended.
[0031]
The rebound stopper 30 in FIG. 5 is different from the rebound stopper 20 in that convex portions 31A and 32A are provided on the upper and lower end surfaces, a notch 31 is provided between the adjacent convex portions 31A, and between the adjacent convex portions 32A. The notch 32 is formed, and the notches 31 and 32 are connected to the annular gap 23 to provide a working oil escape path.
[0032]
Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. Is included in the present invention.
[0033]
【The invention's effect】
As described above, according to the present invention, in the rebound stopper structure of the damper, it is possible to avoid the occurrence of an oil lock state accompanying the deformation of the rebound stopper, and to improve the durability of the rebound stopper.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a main part of a damper.
2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 shows a rebound stopper, (A) is a cross-sectional view, and (B) is an end view.
FIG. 4 is a schematic cross-sectional view showing a compression deformation state of the rebound stopper.
FIG. 5 is a cross-sectional view showing a modified example of the rebound stopper.
[Explanation of symbols]
10 Damper 11 Cylinder 12 Piston rod 13 Rod guide 16 Rebound sheet 20, 30 Rebound stopper 23 Annular gaps 24, 25, 31, 32 Notch

Claims (1)

It has a piston rod inserted into the cylinder, and has a rebound stopper on the outer periphery of the piston rod inside the cylinder.
The rebound stopper is a damper configured to be elastically compressed and deformed by being pressed between a rebound seat provided on the piston rod and a rod guide provided on the cylinder when the piston rod is fully extended, and is in contact with the inner periphery of the cylinder . In the rebound stopper structure,
An annular gap is provided between the inner periphery of the rebound stopper and the outer periphery of the piston rod,
And while providing a notch on the upper end surface of the rebound stopper,
Provide a notch on the lower end of the rebound stopper,
Protrusions are provided at a plurality of positions in the circumferential direction on the inner periphery of the rebound stopper, and the rebound stopper abuts against the piston rod to form an annular gap.
A damper rebound stopper structure characterized in that a cross-sectional area of a notch provided on the upper and lower end faces of the rebound stopper is set larger than a cross-sectional area of an annular gap provided between the outer periphery of the piston rod .

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