JP4233898B2 - Hydraulic shock absorber for suspension system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic shock absorber used for, for example, a strut suspension device of an automobile.
[0002]
[Prior art]
Such hydraulic shock absorbers are known, for example, from Patent Document 1 and Patent Document 2 below. If the hydraulic shock absorber used in the strut type suspension device of an automobile has insufficient bending rigidity, the camber or caster of the tire may change and the characteristics of the suspension device may be affected. This problem becomes prominent when the hydraulic shock absorber is made of aluminum and has low bending rigidity, especially when the outer tube of the hydraulic shock absorber is attached to the knuckle via the bracket. Large stress concentrations may occur and adversely affect durability. Thus, conventionally, bending rigidity and durability have been ensured by increasing the outer diameter of the outer tube of the hydraulic shock absorber or increasing the wall pressure of the outer tube.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-12530
[Patent Document 2]
Japanese Patent Laid-Open No. 2001-59536
[Problems to be solved by the invention]
However, when the outer diameter of the outer tube of the hydraulic shock absorber is increased, there is a problem that it is difficult to store the outer tube in the tire house, and when the outer tube is thickened, the weight is increased.
[0006]
The present invention has been made in view of the above-described circumstances, and an object thereof is to increase the bending rigidity and durability of the suspension apparatus while minimizing the increase in the size and weight of the hydraulic shock absorber.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, according to the invention described in claim 1, a piston rod, a piston provided at the lower end of the piston rod, an inner cylinder in which the piston is slidably fitted, and an inner cylinder The outer tube that fits the outer periphery of the inner cylinder, the oil filled in the inner cylinder and the outer tube, and the piston opens and closes with the relative movement in the axial direction of the piston with respect to the inner cylinder. In a hydraulic shock absorber of a suspension device having a throttle valve that is generated and a bracket that is fixed to the outer periphery of the outer tube and is coupled to a knuckle, an annular reinforcing member that allows oil to pass through is fixed to the inner periphery of the outer tube. And the inner periphery of the reinforcing member is brought into contact with the outer periphery of the inner cylinder. The fixing portion and the axial length of the relative inner circumference of the outer periphery of the outer tube, set longer than the axial length of the contact portion against the outer periphery of the inner periphery of the inner cylinder of the reinforcing member Subeku, the reinforcing member, The shape of the cross section including the axis is formed in a trapezoidal shape in which the inner periphery of the reinforcing member is a first base and the outer periphery is a second base longer than the first base, and the outer tube of the reinforcing member A hydraulic shock absorber for a suspension device is proposed in which the fixing position to the upper half of the bracket is set to the upper half of the fixing range with respect to the outer tube.
[0008]
According to the above configuration, when the outer tube of the hydraulic shock absorber of the suspension device is attached to the knuckle via the bracket, a large stress concentration is generated in the fixing portion between the outer tube and the bracket. By fixing the reinforcing member, it is possible to increase the bending rigidity of the outer tube and relax the stress concentration. Particularly, since the reinforcing member is fixed to the upper half of the fixing range of the bracket with respect to the outer tube, it is possible to effectively reinforce the portion of the outer tube where stress is most concentrated, thereby enhancing durability. In addition, the outer diameter of the hydraulic shock absorber is not increased by the reinforcing member, and the increase in weight is negligible for the weight of the reinforcing member.
[0009]
Further, since the inner periphery of the annular reinforcing member is brought into contact with the outer periphery of the inner cylinder, the bending rigidity of the hydraulic shock absorber can be further increased by connecting the outer tube and the inner cylinder with the reinforcing member. Moreover, the shape of the cross section including the axis of the piston of the reinforcing member is formed in a trapezoidal shape in which the inner periphery of the reinforcing member is the first base and the outer periphery is the second base that is longer than the first base. , the length Kushida than the length of the contact portion with respect to the inner periphery of Lee down donor cylinder of the reinforcing member the length of the fixing portion relative to the outer tube of the outer periphery of the reinforcing member, the bending rigidity of the outer tube is suddenly changed by the reinforcing member And stress concentration on the outer tube can be further relaxed. In addition, since the length that the reinforcing member is press-fitted into the inner periphery of the outer tube increases, the reinforcing member can be firmly fixed to the outer tube, and the length that the reinforcing member contacts the outer periphery of the inner cylinder. Therefore, the inner cylinder can be lightly press-fitted into the reinforcing member later, and the assemblability is improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples of the present invention shown in the accompanying drawings.
[0011]
1 and 2 show a reference example of the present invention. FIG. 1 is a longitudinal sectional view of a hydraulic shock absorber, and FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG.
[0012]
As shown in FIGS. 1 and 2, a hydraulic shock absorber D for an automobile strut suspension device includes a bottomed cylindrical outer tube 11 whose lower end is closed and whose upper end is open, and welded to the lower end. The bracket 11a is fastened to a knuckle (not shown) with a bolt. A cylindrical inner cylinder 12 is coaxially arranged inside the outer tube 11 so as to share the axis L, and a valve block 13 is arranged between the lower end of the inner cylinder 12 and the bottom wall of the outer tube 11. The rod guide 14 abutting on the upper end of the inner cylinder 12 and the seal holder 15 superimposed on the upper surface thereof are fixed to the upper end of the outer tube 11 by caulking.
[0013]
The piston rod 17 that is slidably supported by the rod guide 14 and penetrates the seal member 16 provided in the center of the seal holder 15 in a liquid-tight manner has a mounting portion 17a at its upper end attached to a body frame (not shown) to a rubber bush joint. And a piston 18 provided at the lower end thereof is slidably fitted to the inner cylinder 12. A stopper rubber 19 is provided at an intermediate portion of the piston rod 17, and the amount of protrusion of the piston rod 17 at the time of full rebound is regulated by the stopper rubber 19 coming into contact with the rod guide 14.
[0014]
The inside of the inner cylinder 12 is partitioned into an upper chamber 20 and a lower chamber 21 by a piston 18, and a throttle valve 22 with a check function for connecting the upper chamber 20 and the lower chamber 21 is provided in the piston 18. Further, an outer chamber 23 is formed between the outer tube 11 and the inner cylinder 12, and a communication passage 13 a formed in the valve block 13 to connect the outer chamber 23 and the lower chamber 21 of the inner cylinder 12, Throttle valves 24 with check functions are provided. The upper chamber 20, the lower chamber 21, and the outer chamber 23 are filled with oil 25. The upper portion of the outer chamber 23 functions as a reservoir filled with air.
[0015]
The outer periphery of the annular reinforcing member 26 is fixed to the inner periphery of the outer tube 11 by press fitting. An annular gap is formed between the inner periphery of the reinforcing member 26 and the outer periphery of the inner cylinder 12, so that free circulation of the oil 25 is not hindered. The fixing position of the reinforcing member 26 is set in the upper half B of the fixing range A of the bracket 11 a with respect to the outer tube 11. That is, even when the reinforcing member 26 is at the upper limit position 26U, at least a part thereof overlaps the upper end of the upper half B, and even when the strong member 26 is at the lower limit position 26L, at least a part thereof is the upper half. It is set so as to overlap the lower end of the part B.
[0016]
Next, the operation of the reference example having the above configuration will be described.
[0017]
When the piston rod 17 rebounds from the outer tube 11, the throttle valves 22 provided on the piston 18 perform a throttle function and the throttle valves 24 provided on the valve block 13 are opened. As a result, the oil 25 in the upper chamber 20 of the inner cylinder 12 whose volume decreases with the upward movement of the piston 18 flows into the lower chamber 21 of the inner cylinder 12 while passing through the throttle valve 22 of the piston 18. At this time, a damping force is generated by the viscous resistance of the oil 25 passing through the throttle valves 22. At this time, the oil 25 corresponding to the volume of the piston rod 17 projecting from the upper chamber 20 through the rod guide 14 passes through the throttle valve 24 opened from the outer chamber 23 of the outer tube 11 to the valve block 13. Then, it flows into the lower chamber 21 of the inner cylinder 12 without resistance.
[0018]
On the other hand, when the piston rod 17 is pressed into the outer tube 11, the throttle valves 22 provided on the piston 18 are opened, and the throttle valves 24 provided on the valve block 13 exhibit a throttle function. As a result, the oil 25 pushed out from the lower chamber 21 in which the volume of the inner cylinder 12 decreases passes through the throttle valves 22 of the piston 18 without resistance and flows into the upper chamber 20 in which the volume increases. At this time, the oil 25 corresponding to the volume of the piston rod 17 inserted into the upper chamber 20 through the rod guide 14 flows from the lower chamber 21 through the throttle valve 24 of the valve block 13 into the outer chamber 23. At that time, a damping force is generated by the viscous resistance of the oil 25 passing through the throttle valves 24.
[0019]
As described above, when the outer tube 11 having the lower end connected to the knuckle and the piston rod 17 having the upper end connected to the vehicle body frame move relative to each other in the direction of the axis L to generate a damping force, the hydraulic shock absorber D Bending moment acts on When the hydraulic shock absorber D is bent and deformed by this bending moment, the camber and caster of the tire may change and the characteristics of the suspension device may be affected. Therefore, the bending deformation of the hydraulic shock absorber D can be minimized. desirable. Further, when a bending moment acts on the hydraulic shock absorber D, the greatest stress concentration occurs at the upper end portion 11b of the fixing portion between the outer tube 11 and the bracket 11a, which may adversely affect the durability of the outer tube 11. .
[0020]
In this reference example, since the annular reinforcing member 26 is press-fitted into the inner periphery of the outer tube 11, the outer tube 11 can be reinforced by the reinforcing member 26 to increase the bending rigidity of the hydraulic shock absorber D. The outer diameter of the vessel D is not increased by the reinforcing member 26, and the increase in weight is a slight amount corresponding to the weight of the reinforcing member 26.
[0021]
When the outer tube 11 is attached to the knuckle via the bracket 11a, a large stress concentration occurs in the fixing range A of the bracket 11a with respect to the outer tube 11 (particularly the upper half B of the fixing range A). By fixing the annular reinforcing member 26 around the circumference, the bending rigidity of the outer tube 11 can be increased and the stress concentration can be reduced. In particular, since the reinforcing member 26 is fixed to the upper half B of the fixing range A of the bracket 11a with respect to the outer tube 11, it is possible to effectively reinforce the portion of the outer tube 11 where stress is most likely to concentrate to enhance durability. it can.
[0022]
3 and 4 show a first embodiment of the present invention. FIG. 3 is a longitudinal sectional view of the hydraulic shock absorber, and FIG. 4 is an enlarged sectional view taken along line 4-4 of FIG. In addition, in 1st Example, the description which overlaps by omitting the same code | symbol as a reference example to the member corresponding to the member of a reference example is abbreviate | omitted.
[0023]
The first embodiment is different from the reference example only in the structure of the reinforcing member 26, and the other structures are the same as those in the reference example. That is, the outer periphery of the reinforcing member 26 of the first embodiment is fixed to the inner periphery of the outer tube 11 by press-fitting, and the inner periphery is in contact with or weakly press-fitted to the outer periphery of the inner cylinder 12. The reason why the inner circumference of the reinforcing member 26 is not press-fitted strongly into the outer circumference of the inner cylinder 12 is that smooth sliding of the piston 18 may be hindered when the inner cylinder 12 is deformed by the press-fitting load.
[0024]
The cross section of the reinforcing member 26 is trapezoidal, and the length a in the axis L direction of the fixed portion with respect to the inner circumference of the outer tube 11 is longer than the length b in the axis L direction of the contact portion with respect to the outer circumference of the inner cylinder 12. ing. The reinforcing member 26 is formed with a plurality of (seven in the embodiment) through-holes 26a for allowing the oil to flow.
[0025]
The fixing position of the reinforcing member 26 is the same as in the reference example, and even when the reinforcing member 26 is at the upper limit position, at least a part of the reinforcing member 26 is at the upper end of the upper half B of the fixing range A of the bracket 11a to the outer tube 11. Even when the strong member 26 is in the lower limit position, at least a part of the strong member 26 is set to overlap the lower end of the upper half B.
[0026]
According to this 1st Example, in addition to the effect of a reference example, the following further effects can be achieved. That is, since the cross section of the reinforcing member 26 has a trapezoidal shape, and the radial thickness of the upper portion thereof gradually increases from the top to the bottom, the reinforcing member when a bending moment acts on the outer tube 11. The rigidity of 26 increases gradually from top to bottom. Therefore, the bending strength of the outer tube 11 can be prevented from changing suddenly by the reinforcing member 26, stress concentration can be reduced, and the durability of the fixing portion of the bracket 11a with respect to the outer tube 11 can be further effectively enhanced.
[0027]
In addition, since the length a in which the reinforcing member 26 is press-fitted into the inner periphery of the outer tube 11 is increased, the reinforcing member 26 can be firmly fixed to the outer tube 11. Furthermore, since the length b with which the reinforcing member 26 comes into contact with the outer periphery of the inner cylinder 12 becomes small, the inner cylinder 12 can be lightly press-fitted into the reinforcing member 26 later, and the assembling property is improved.
[0028]
5 and 6 show a second embodiment of the present invention. FIG. 5 is a longitudinal sectional view of the hydraulic shock absorber, and FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. In addition, in 2nd Example, the overlapping description is abbreviate | omitted by attaching | subjecting the code | symbol same as a reference example to the member corresponding to the member of a reference example.
[0029]
The second embodiment is a modification of the first embodiment. In the first embodiment, seven large-diameter through holes 26a are formed in the reinforcing member 26, and the throttling effect is exerted on the through holes 26a. Although not expected, in the second embodiment, the damping characteristic of the hydraulic shock absorber D can be tuned by providing the reinforcing member 26 with a small number (for example, two) of the throttles 26b, 26c having a small passage cross-sectional area.
[0030]
While the embodiments and reference examples of the present invention have been described above, various design changes can be made without departing from the scope of the present invention.
[0031]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the outer tube of the hydraulic shock absorber of the suspension device is attached to the knuckle via the bracket, a large stress concentration occurs in the fixing portion between the outer tube and the bracket. However, by fixing the annular reinforcing member to the inner periphery of the outer tube, it is possible to increase the bending rigidity of the outer tube and relieve the stress concentration. Particularly, since the reinforcing member is fixed to the upper half of the fixing range of the bracket with respect to the outer tube, it is possible to effectively reinforce the portion of the outer tube where stress is most concentrated, thereby enhancing durability. In addition, the outer diameter of the hydraulic shock absorber is not increased by the reinforcing member, and the increase in weight is negligible for the weight of the reinforcing member.
[0032]
Further, since the inner periphery of the annular reinforcing member is brought into contact with the outer periphery of the inner cylinder, the bending rigidity of the hydraulic shock absorber can be further increased by connecting the outer tube and the inner cylinder with the reinforcing member. Moreover, the shape of the cross section including the axis of the piston of the reinforcing member is formed in a trapezoidal shape in which the inner periphery of the reinforcing member is the first base and the outer periphery is the second base that is longer than the first base. , the length Kushida than the length of the contact portion with respect to the inner periphery of Lee down donor cylinder of the reinforcing member the length of the fixing portion relative to the outer tube of the outer periphery of the reinforcing member, the bending rigidity of the outer tube is suddenly changed by the reinforcing member And stress concentration on the outer tube can be further relaxed. In addition, since the length that the reinforcing member is press-fitted into the inner periphery of the outer tube increases, the reinforcing member can be firmly fixed to the outer tube, and the length that the reinforcing member contacts the outer periphery of the inner cylinder. Therefore, the inner cylinder can be lightly press-fitted into the reinforcing member later, and the assemblability is improved.
[Brief description of the drawings]
1 is a longitudinal sectional view of a hydraulic shock absorber. FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1. FIG. 3 is a longitudinal sectional view of a hydraulic shock absorber according to a first embodiment. -4 line enlarged sectional view [FIG. 5] longitudinal sectional view of the hydraulic shock absorber according to the second embodiment [FIG. 6] 6-6 line enlarged sectional view of FIG.
DESCRIPTION OF SYMBOLS 11 Outer tube 11a Bracket 12 Inner cylinder 17 Piston rod 18 Piston 22 Throttle valve 24 Throttle valve 25 Oil 26 Reinforcement member L Axis A Fixing range B to outer tube of bracket B Upper half of fixing range a Length of fixing part in axial direction b Axial length of contact area

Claims (1)

A piston (18) provided at the lower end of the piston rod (17);
An inner cylinder (12) in which a piston (18) is slidably fitted;
An outer tube (11) fitted to the outer periphery of the inner cylinder (12);
Oil (25) filled in the inner cylinder (12) and the outer tube (11);
Throttle valves (22, 24) that open and close with relative movement of the piston (18) in the axis (L) direction with respect to the inner cylinder (12) and generate a damping force by the viscous resistance of the oil (25) passing therethrough ,
A bracket (11a) fixed to the outer periphery of the lower portion of the outer tube (11) and coupled to the knuckle;
In the hydraulic shock absorber of the suspension device comprising:
An annular reinforcing member (26) through which oil can pass is fixed to the inner circumference of the outer tube (11), and the inner circumference of the reinforcing member (26) is brought into contact with the outer circumference of the inner cylinder (12) to thereby reinforce the reinforcement. member (26) outer periphery of the outer tube (11) fixed portion of said axis against the inner periphery of the (L) direction of the length of (a), for the outer periphery of the inner periphery of the inner cylinder of the reinforcing member (26) (12) the axis (L) direction of the length (b) than longer set Subeku the contact portion, of the reinforcing member (26), the axis shape of the cross section including (L), of the reinforcing member (26) A trapezoidal shape with a circumference serving as a first base and a circumference serving as a second bottom longer than the first base is formed, and the fixing position of the reinforcing member (26) to the outer tube (11) is defined by a bracket ( 11a) on the outer tube (11) A hydraulic shock absorber of the suspension device being characterized in that set in the upper half of the fixed range (A) (B) to.

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