JP3606538B2 - Damping force variable hydraulic buffer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic shock absorber used for an automobile suspension or the like, and more particularly, to a variable damping force hydraulic shock absorber capable of adjusting a generated damping force by an actuator.
[0002]
[Prior art]
As a damping force variable hydraulic shock absorber, an actuator such as a step motor is attached to the tip of the piston rod, and its output shaft is connected to a damping force variable mechanism inside the cylinder via a control rod that penetrates the piston rod. There is something that was made. In the case of this type of hydraulic shock absorber, when the actuator is attached, it is necessary to accurately align the initial position of the actuator and the initial position of the damping force variable mechanism. For this purpose, the actuator output shaft is a so-called control rod. The coupling is performed by fitting with a two-surface width or the like, and the actuator main body is coupled with the piston rod positioned in the rotational direction.
[0003]
If the relative position of the actuator body and the piston rod slightly shifts, the setting of the damping force variable mechanism will shift and the desired damping force will not be obtained. High positioning accuracy is required. For this reason, for example, the coupling of both forms, for example, a two-surface width portion having positioning planes parallel to each other along the axial direction at the tip portion of the piston rod, while the actuator bracket has a cross section of the two-surface width portion. A mounting hole with a corresponding shape is formed, the actuator bracket is fitted to the two-surface width part, and is fastened and fixed to the piston rod with a nut, and then the actuator output shaft is connected to the tip of the control rod as described above. The actuator body is fixed by a fixing bracket or the like while appropriately rotating and adjusting the actuator body relative to the actuator bracket. In this case, since the piston rod and the actuator are fitted in the two-surface width portion, both are positioned with very high accuracy in the rotation direction.
[0004]
By the way, when the front end of the piston rod is coupled to the vehicle body via the vehicle body mounting mount, the mounting hole formed in the vehicle body mounting mount is inserted into the front end portion of the piston rod, and the vehicle body mounting mount is mounted in this state. Although it is attached to the piston rod by tightening with a nut or the like, it is necessary to fit the mount for mounting the vehicle body and the piston rod in a state where the relative rotation of both is restricted in consideration of the assembly of the subsequent parts to the piston rod. In other words, after attaching the vehicle body mounting mount to the piston rod, when the actuator bracket or the output shaft of the actuator is further fitted to the tip of the piston rod as described above, if the piston rod rotates, Since the fitting work becomes very difficult, the rotation of the piston rod must be suppressed by locking the vehicle body mounting mount. On the other hand, since the load from the vehicle body and the load from the suspension spring are applied to the coupling portion between the piston rod and the vehicle body mounting mount, a relatively high strength is required.
[0005]
For this reason, in the damping force variable hydraulic shock absorber of the type in which the vehicle body mounting mount is attached to the piston rod, a D-cut portion is further formed on the base side of the two-surface width portion of the piston rod. The D-cut mounting holes of the vehicle body mounting mount are fitted into the mounting holes. In this case, the positioning plane of the D-cut portion is formed continuously with one of the two width portions on the front end side of the D-cut portion, and when the vehicle body mounting mount is fitted to the D-cut portion, the mounting of the mount The straight cut portion of the hole can be guided by one positioning plane of the two-surface width portion. Thus, when the piston rod and the vehicle body mounting mount are positioned by fitting by D-cut, it is advantageous in terms of the strength of the piston rod, and the piston rod can be more firmly fixed to the vehicle body side. .
[0006]
This similar technique is disclosed in, for example, JP-A-8-4817.
[0007]
[Problems to be solved by the invention]
However, in the conventional hydraulic shock absorber, since the two positioning planes of the two-surface width portion are formed with respect to the axis of the piston rod, the body mounting mount is different in the direction of 180 ° from the piston. Even when trying to assemble to the rod, the mounting hole of the mount is inserted into the width of the two sides of the tip of the piston rod, which slows down the discovery of assembly errors and reduces production efficiency. There is a problem of coming.
[0008]
In particular, since the suspension spring is already assembled before the vehicle body mounting mount is assembled to the piston rod, the nut is tightened in the state where the mounting hole of the vehicle body mounting mount is inserted at the end of the two-surface width portion. This is often done against the force of the spring, and in such a case, if there is an error in the mounting direction of the vehicle body mounting mount as described above, the error will be discovered only after the tightening of the nut has progressed. This leads to a significant reduction in production efficiency.
[0009]
Therefore, the present invention provides a variable damping force type hydraulic shock absorber that can quickly find an error in the mounting direction of the vehicle body mounting mount during the assembly work and can greatly improve productivity. It is something to try.
[0010]
[Means for Solving the Problems]
According to the present invention, as a means for solving the above-mentioned problems, a vehicle body mounting mount is positioned and fitted and mounted in the rotational direction at the tip of a piston rod projecting forward and backward from a cylinder. Further, an actuator bracket is similarly positioned and fitted in the rotational direction on the distal end side of the cylinder, while an actuator for driving a variable damping force mechanism inside the cylinder is disposed at the distal end of the piston rod. A damping force variable type hydraulic shock absorber coupled to an actuator bracket, wherein a D-cut portion having one mount positioning plane along an axial direction is provided at a tip end portion of the piston rod, and a piston is mounted from the mount positioning plane. A first positioning plane continuous to the rod tip side and a second positioning parallel to the first positioning plane A two-surface width portion having a flat surface is formed, and the mounting hole having a shape corresponding to the cross section of the D-cut portion and the attachment corresponding to the cross section of the two-surface width portion are formed in the vehicle body mounting mount and the actuator bracket, respectively. In the case where the hole is formed, the distance from the axial center of the piston rod is longer on the second positioning plane side than on the first positioning plane side between the first positioning plane and the second positioning plane of the two-surface width portion. It was made to form asymmetrically.
[0011]
When the vehicle body mounting mount is to be assembled to the piston rod at a different angle of 180 °, the straight cut portion of the mounting hole of the vehicle body mounting mount is the axial center of the piston rod of the two-surface width portions. Therefore, the vehicle body mounting mount cannot be inserted into the two-surface width portion. Therefore, an error in the mounting direction of the vehicle body mounting mount can be found immediately at that time.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to FIGS.
[0013]
FIG. 2 shows a suspension of an automobile adopting the damping force variable hydraulic shock absorber 1 according to the present invention. In FIG. 2, reference numeral 2 denotes a suspension spring assembled to the vehicle body together with the hydraulic shock absorber 1 according to the present invention. .
[0014]
The hydraulic shock absorber 1 has a so-called twin tube structure having an outer cylinder 3 and an inner cylinder 4. A bracket 5 coupled to a wheel spindle is attached to the lower end of the outer cylinder 3. A piston 7 having a damping force variable mechanism 6 is slidably accommodated. A piston rod 8 extending upward from the end surface of the outer cylinder 3 is coupled to the piston 7, and the tip of the piston rod 8 is coupled to the vehicle body panel 10 via a strut mount 9 that is a vehicle body mounting mount. Has been. An actuator 11 such as a step motor for rotationally driving the damping force variable mechanism 6 is attached to the distal end portion of the piston rod 8 penetrating the strut mount 9 via an actuator bracket 12.
[0015]
The output shaft 13 of the actuator 11 is coupled to the damping force variable mechanism 6 by a control rod 14 that passes through the piston rod 8. The base portion of the control rod 14 is coupled to the damping force variable mechanism 6 in advance, and the output shaft 13 of the actuator 11 is positioned in the rotational direction by fitting with the two-surface width at the tip portion penetrating the piston rod 8. Engaged in a state.
[0016]
On the other hand, a step-shaped support surface 15 is formed at the tip of the piston rod 8 as shown in FIGS. 1 and 3. A D-cut portion 17 having one mount positioning plane 16 along the axial direction and a two-surface width portion 20 having first and second positioning planes 18 and 19 parallel to each other along the axial direction are formed. . Of these, the two-surface width portion 20 is positioned on the tip end side of the piston rod 8 of the D-cut portion 17, and the first positioning plane 18 is continuous to the tip end side of the piston rod 8 with respect to the mount positioning plane 16 of the D-cut portion 17. Thus, it is formed (on the same plane). A male screw 21 is cut on the outer peripheral surface of each of the D-cut portion 17 and the two-plane width portion 20 excluding the positioning plane portions 16, 18, and 19. Further, a cylindrical portion 22 having an outer diameter smaller than that of the two-surface width portion 20 is formed on the front end side of the two-surface width portion 20 of the piston rod 8, and this cylindrical portion 22 is formed on the lower surface of the main body portion 23 of the actuator 11. It is adapted to be fitted into a circular recess 24.
[0017]
The strut mount 9 includes a bottomed cylindrical inner cylinder fitting 25, an outer cylinder fitting 27 having an upper edge flange 26, an insulator rubber 28 connecting the inner and outer cylinder fittings 25, 27, and a shaft of the insulator rubber 28. And a stopper plate 29 for restricting excessive deformation in the direction. The bottom wall of the inner cylinder fitting 25 and the stopper plate 29 are fastened together with the nut 30 to the D-cut portion 17 of the piston rod 8 in a superposed state. The upper edge flange 26 is coupled to the vehicle body panel 10 by bolts 32. When assembling the strut mount 9 to the piston rod 8, the mounting holes 33 and 34 formed in the bottom wall of the inner metal fitting 25 and the stopper plate 29 are fitted into the D-cut portion 17 of the piston rod 8. The mounting holes 33, 34 are formed in a shape corresponding to the cross section of the D-cut portion 17, that is, a shape having one straight cut portion 33a, 34a, and the straight cut portions 33a, 34a are inserted into the D-cut portion when fitted. By abutting on the mount positioning plane 16, the inner cylinder fitting 25 and the stopper plate 29 and the piston rod 8 are fixed in the rotational direction, and the piston rod 8 does not rotate when the nut 30 is fastened. .
[0018]
The actuator bracket 12 is formed in a bottomed cylindrical shape, and a mounting hole 35 formed in the bottom wall of the actuator bracket 12 is fitted into the two-surface width portion 20 of the piston rod 8. It is fastened to the part 20. The mounting hole 35 of the actuator bracket 12 is formed in a shape corresponding to the cross section of the two-surface width portion 20, that is, a shape having first and second straight cut portions 35a and 35b parallel to each other.
[0019]
2, 37 is a lower spring seat that is fixed to the outer periphery of the outer cylinder 3 and supports the lower end of the suspension spring 2, and 38 is engaged with the lower surface of the strut mount 9 via a thrust bearing 39. An upper spring seat 40 that supports the upper end of the suspension spring 2 is a bumper bar that is attached to the lower surface of the upper spring seat 38 and elastically restricts excessive displacement of the hydraulic shock absorber 1.
[0020]
By the way, the two-surface width portion 20 of the piston rod 8 is formed asymmetrically with respect to the axis O. More specifically, the first positioning plane 18 and the second positioning plane 19 of the two-surface width portion 20 are not exactly the same distance from the axis O of the piston rod 8, and the distance b on the second positioning plane 19 side is the first distance b. It is set to be longer than the distance a on the one positioning plane 18 side.
[0021]
For this reason, the mounting hole 35 of the actuator bracket 12 having a shape corresponding to the cross section of the two-surface width portion 20 is also the distance from the axis O to the first straight cut portion 35a and from the axis O to the second straight cut portion 35b. The distances are set differently as well.
[0022]
Hereinafter, assembly of the strut mount 9, the actuator 11, and the actuator bracket 12 with respect to the tip portion of the piston rod 8 will be described.
[0023]
First, after the suspension spring 2 and the like are assembled to the hydraulic shock absorber 1, the mounting holes 33 and 34 of the strut mount 9 are inserted into the distal end portion of the piston rod 8, and the mounting holes 33 and 34 are connected to the D of the piston rod 8. A nut 30 is attached to the tip of the piston rod 8 in a state of being fitted to the cut portion 17, and the nut 30 is tightened in a state where the piston rod 8 is fixed to the inner cylinder fitting 25 and the stopper plate 29 in the rotational direction.
[0024]
Subsequently, in this state, the mounting hole 35 of the actuator bracket 12 is inserted into the distal end portion of the piston rod 8, and the distal end portion of the piston rod 8 is fitted in the mounting hole 35 to the two-surface width portion 20 of the piston rod 8. A nut 36 is screwed onto the actuator bracket 12 to fix the actuator bracket 12 to the two-surface width portion 20 while being positioned in the rotational direction.
[0025]
Thereafter, the actuator 11 is brought close to the tip of the piston rod 8, and the output shaft 13 of the actuator 11 is fitted to the control rod 14 in a rotational direction, and the cylindrical portion 22 at the tip of the piston rod 8 is fitted. The actuator 11 is fitted in the recess 24 of the main body 23. In this state, the main body 23 of the actuator 11 is appropriately rotated and aligned with the actuator bracket 12 in the rotational direction.
[0026]
As described above, the actuator 11 is attached in a state where the initial position of the actuator 11 and the initial position of the damping force variable mechanism 6 are accurately aligned.
[0027]
By the way, when the strut mount 9 is inserted into the distal end portion of the piston rod 8 as described above, if the orientation of the strut mount 9 is a normal orientation, the strut mount 9 is attached as shown in FIG. When the straight cut portions 33a and 34a of the holes 33 and 34 are guided by the first positioning plane 18 of the two-surface width portion 20 and are fitted to the D-cut portion 17, the strut mount 9 is different in direction by 180 °. In addition, the mounting holes 33 and 34 of the strut mount 9 cannot be inserted into the two-surface width portion 20.
[0028]
This is because the distances a and b from the axis O of the two-surface width portion 20 to the first and second positioning planes 18 and 19 are set as b> a. That is, the D-shaped mounting holes 33 and 34 of the strut mount 9 have the same distance a from the axial center O to the straight cut portions 33a and 34a as the first positioning plane 18 side, so that the distances a and b are b. If the relationship is> a, when the strut mount 9 is about to be inserted into the two-surface width portion 20 with the straight cut portions 33a and 34a facing the second positioning plane 19 side, the distances a and b are b. When the relationship is> a, the straight cut portions 33a and 34a of the strut mount 9 naturally interfere with the second positioning plane 19 as shown in FIG.
[0029]
Therefore, in this hydraulic shock absorber 1, the strut mount 9 is not inserted into the two-surface width portion 20 of the piston rod 8 in the wrong direction. For this reason, it is possible to reliably detect an error in the orientation of the strut mount 9 before starting the tightening of the nut 30 with respect to the piston rod 8, and to securely tighten the nut 30 in a state in which the orientation of the strut mount 9 is incorrect. It can be avoided. Therefore, unnecessary work that is not necessary can be reduced, and the production efficiency is surely improved as compared with the conventional one.
[0030]
【The invention's effect】
As described above, according to the present invention, the distance from the axial center of the piston rod is longer on the second positioning plane side than on the first positioning plane side. By forming it asymmetrically, the vehicle body mounting mount cannot be inserted into the two-sided width portion when the vehicle body mounting mount is to be assembled with a 180 ° orientation different from the piston rod. An error in the mounting direction can be immediately detected at that time, and therefore, the assembly of the body mounting mount in the wrong direction can be completely eliminated, and the production efficiency can be greatly improved.
[Brief description of the drawings]
FIG. 1 is an enlarged cross-sectional view of a main part showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the overall structure of the embodiment.
FIG. 3 is an exploded sectional view of a waist portion showing the embodiment.
FIG. 4 is a plan view showing the embodiment.
[Explanation of symbols]
1 ... Hydraulic buffer
3. Outer cylinder (cylinder),
6 ... Damping force variable mechanism,
8 ... Piston rod,
9 ... Strut mount (mounting for vehicle mounting),
11 ... Actuator,
12 ... Actuator bracket,
16 ... Mount positioning plane,
17 ... D cut part,
18 ... 1st positioning plane,
19 ... 2nd positioning plane,
20 ... 2 side width part,
33, 34, 35 ... mounting holes,
O ... Axis center.

Claims (1)

A vehicle body mounting mount is positioned and fitted in the rotational direction at the tip of a piston rod that protrudes and retracts from the cylinder, and an actuator bracket is also positioned in the rotational direction at the tip of the piston rod. On the other hand, an actuator that drives a variable damping force mechanism inside the cylinder is disposed at the tip of the piston rod, and is coupled to the actuator bracket. The front end portion of the piston rod has a D-cut portion having one mount positioning plane along the axial direction, a first positioning plane continuous from the mount positioning plane to the front end side of the piston rod, and the first A two-sided width portion having a second positioning plane parallel to the positioning plane, Mounting and actuator bracket in which the mounting hole having a shape corresponding to the cross section of the mounting hole and the second surface width portion having a shape corresponding to the cross section of each said D-cut portion is formed,
The first positioning plane and the second positioning plane of the two-surface width portion are formed asymmetrically such that the distance from the axial center of the piston rod is longer on the second positioning plane side than on the first positioning plane side. Damping force variable hydraulic buffer.

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