JPH0617703B2 - Hydraulic shock absorber - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force variable hydraulic shock absorber used in a vehicle or the like, and more particularly to a hydraulic shock absorber capable of variably controlling generated damping force by remote operation of a motor. Is.

As is well known in the prior art, a hydraulic shock absorber that can vary the generated damping force in multiple steps adjusts the damping force to the suspension characteristics of the vehicle that match the running road surface condition and the vehicle posture, and The controllability of vehicle stability is ensured, and the drive force is switched by electronically controlling the damping force or by a manual switch disposed in the driver's seat.

In particular, the damping force is variable by switching the operating flow rate of the hydraulic fluid that bypasses the upper and lower chambers of the cylinder of the hydraulic shock absorber, for example, to large (soft state) / medium (normal state) / small (hard state) by driving the motor. In the hydraulic shock absorber of type, the control mode has multiple stages, and the maneuverability / stability of the vehicle can be controlled in response to all running conditions and road surface conditions including vehicle attitude control during acceleration / deceleration / turning of the vehicle. It has the feature of being able to control the riding comfort and is becoming the mainstream of the current damping force variable hydraulic shock absorber.

As conventional techniques of this motor-driven damping force variable hydraulic shock absorber, there are techniques disclosed in US Pat. No. 3,599,776 and JP-A-55-65741. That is, the motor is arranged at the upper end of the piston rod, the adjuster is provided at the lower part of the piston rod, and the adjuster is driven by the motor through the shaft penetrating the hollow hollow portion of the piston rod.

However, in the structure in which the motor is attached to the upper portion of the piston rod and the adjuster at the lower portion of the piston rod is rotationally driven via the control shaft to adjust the damping force, the following is performed. However, various problems have occurred.

That is, (1) since the motor is arranged above the piston rod, a large space above the piston rod is required for arranging the motor, and this space makes the vehicle mounting layout difficult and restricts the vehicle body shape. In the strut type suspension in which the piston rod is directly attached to the vehicle body, the motor needs to be attached after the piston rod is attached to the vehicle body, and there is a problem that the attachment work becomes complicated.

(2) Furthermore, since the adjuster is driven through a long control shaft that extends over almost the entire length of the piston rod, the weight of the control shaft increases, and
There is inevitably a friction torque between the control shaft and the inner surface of the hole of the piston rod, and it is necessary to increase the driving torque of the motor. The large friction torque deteriorates the control accuracy of the rotational position of the adjuster.

In particular, since a passage communicating with the upper liquid chamber is formed between the control shaft and the hole of the piston rod through which the control shaft is inserted, a gap between the hole and the control shaft is provided in order to ensure sealing performance. It must be made smaller or a sealing member must be provided. Therefore, the rotational sliding resistance of the control shaft is further increased, the driving load of the motor is increased, and the size is promoted.

(3) Further, since the motor is attached to the outside of the upper part of the piston rod, it has a problem that it is damaged by collision of flying stones from the road surface and rust etc. occurs due to intrusion of muddy water. In consideration of the above, there is a problem that it becomes expensive if a strict protective cover is attached.

(4) Further, the motor generates a certain amount of vibration noise during operation, and has a problem that the vibration noise is directly radiated to the outside from the upper portion of the piston rod where the motor is present.

Further, there is also provided a device in which an electric motor for varying a damping force is housed in a rod hollow portion, as disclosed in, for example, Japanese Utility Model Laid-Open No. 55-109008 and Japanese Patent Laid-Open No. 56-111009. However, since the operation is only in two stages of ON and OFF, it is impossible to control the damping force with high accuracy according to the road surface condition, and it is not possible to sufficiently satisfy the requirements such as vehicle stability. .

Moreover, in this conventional example, since the bypass rod is directly opened and closed by the drive rod of the electric motor, not only must the drive rod be set to a large diameter in accordance with the passage diameter of the bypass passage, If the distance of the bypass passage is long, the drive rod must be set accordingly.

In particular, since the drive rod is stroked up and down to open and close the bypass passage, a length for securing the stroke movement amount is required, which inevitably lengthens the drive rod. Therefore, the weight increases and a large inertial force is generated during the stroke.

Further, since the gap between the drive rod and the insertion hole of the drive rod must be made small in order to secure the sealing property, the sliding resistance of the drive rod increases, and the sliding due to the increase in diameter and the increase in length. Along with the increase in resistance and weight, the driving load of the electric motor is increased and the electric motor is inevitably increased in size.

Means for Solving the Problems The present invention has been devised in view of the above-mentioned various problems of the related art, and a cylinder filled with hydraulic fluid and an end that is inserted into one end of the cylinder so that the cylinder can advance and retreat. And a piston rod having a hollow rod portion in the inner axial direction of the side, and arranged at one end of the piston rod via a tubular member to slide inside the cylinder into an upper liquid chamber and a lower liquid chamber. A piston body that is movably accommodated, and a damping force is generated by imparting flow resistance to the hydraulic fluid that is provided in the piston body and that displaces and flows through the flow path that connects the upper liquid chamber and the lower liquid chamber. Damping force generating means, a bypass passage formed in the tubular member for bypassing the flow passage, and an adjuster for adjusting the generated damping force by changing the passage cross-sectional area of the bypass passage according to its rotational position. And the horse mackerel A hydraulic shock absorber equipped with a motor that rotationally drives the caster based on a control signal of a control means, wherein a cylindrical member that rotatably accommodates the adjuster therein is provided on the opening end side of the hollow rod portion. In addition to fixing, a short cylindrical retainer is fixed to the upper end of the cylindrical member in the hollow portion of the rod, the motor is positioned and fixed on the retainer, and the insertion is formed through the retainer in the axial direction. It is characterized in that the motor and the adjuster are connected by an output shaft inserted through the hole.

Action When the motor in the hollow portion of the rod is rotated by the control means, the damping force can be changed in multiple steps by the rotation control of the adjuster by the output shaft, and the driving noise of the motor surrounds it. It is sufficiently damped by the piston rod, and can be reliably protected from flying stones and muddy water.

Moreover, since the motor is provided while being positioned above the retainer within the hollow portion of the rod, the motor is supported stably and reliably. Further, since the output shaft is connected to the adjuster in the tubular member through the through hole of the retainer, the output shaft can be shortened as much as possible, and the bypass passage is not directly opened / closed but the adjuster is opened. Since it is designed to rotate, the shaft diameter can be made sufficiently small. Therefore, the weight of the output shaft can be reduced, and it is not necessary to consider the wear torque between the output shaft and the piston rod, and the torsional friction torque of the output shaft itself can be reduced. Furthermore, it is not necessary to consider the seal around the output shaft.

Examples Hereinafter, examples of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows an embodiment of the hydraulic shock absorber of the present invention in detail. Reference numeral 1 is a cylinder containing hydraulic fluid, and 2 is a piston rod whose one end extends liquid-tightly through a sealing upper end (not shown) of the cylinder 1. This piston rod 2
Has a small-diameter through-hole 2a formed in the inner axial direction, and a relatively large-diameter rod hollow portion 3 is formed at the lower end of the through-hole 2a. In the vicinity of the boundary between the peripheral wall and the peripheral wall of the hollow rod portion 3, a guide portion 33 having a substantially conical taper whose diameter is gradually reduced from the hollow rod portion 3 toward the through hole 2a is formed.

Further, in the rod hollow portion 3, the motor 4,
A reduction gear unit 5 that reduces the rotation of the motor 4, a position detector 7 that detects the rotation angle of a short output shaft 6 of the reduction gear unit 5, a retainer 8 and a cylindrical adjuster 9 on the inner circumference.
Is rotatably supported and the cylindrical member 10 is accommodated in sequence.

More specifically, the lower end of the motor 4 is fixed to the upper end of a retainer 8 through a column (not shown), and the retainer 8 has a short cylindrical shape with a substantially U-shaped cross section. The outer peripheral edge of the upper end portion is positioned in the axial direction at a position where it abuts against the small-diameter step portion of the hollow rod portion 3, thereby supporting the motor 4 and the reduction gear 5 while positioning them in the axial direction. As a result, stable and reliable support of the motor 4 and the like becomes possible. Further, the tubular member 10 is provided at the lower end portion of the retainer 8, and the tubular member 10 is rod hollow portion by a ring screw 27 screwed into a collar 26 fixed to the outer periphery of the lower end of the piston rod 2. Held within 3. Further, the adjuster 9 rotatably supported in the tubular member 10 is arranged sufficiently close to the motor 4 and the reduction gear 5 via the retainer 8.

Further, the output shaft 6 is connected to the upper end of the adjuster 9 by inserting the output shaft 6 in a non-contact state through an insertion hole 8a formed through the retainer 8 in the central axial direction.
The length of the output shaft 6 is set to be as short as possible only by setting the length thereof to be slightly longer than the length of the retainer 8 in the axial direction.

In the figure, 11 is an O-ring that seals between the inner peripheral surface of the rod hollow portion 3 and the tubular member 10, and 12 is an O-ring that seals between the inner peripheral surface of the tubular member 10 and the outer peripheral surface of the adjuster 9. .

Further, a cutout 13 opening downward is provided at the lower end of the adjuster 9, and passage portions 14, 14 penetrating inside and outside the cutout 13 are provided in a direction perpendicular to the axis. Further, as shown in FIG. 2, four fixed orifices 15, 16, 17, 18 having different diameters penetrate through the tubular member 10 in the portion facing the passage portions 14, 14 in the direction perpendicular to the axis. Is provided. By the rotation of the adjuster 9, the passage portions 14 and 14 selectively oppose two adjacent fixed orifices 15 to 18, and a piston body described later communicates with the shaft passage portion 10a at the lower end of the tubular member 10. The damping force is selected by changing the throttle of the hydraulic fluid that is displaced and flow between the upper liquid chamber 24 and the lower liquid chamber 25 that are separated from each other. 19 is a washer 20 on the outer periphery of the small diameter portion of the tubular member 10,
With a piston body fixed with a nut 21 through 20,
The piston body 19 is provided in the upper and lower liquid chambers 2 in the axial direction.
Disc valves that form flow paths 22, 22 that connect the flow paths 4, 25, and that open and close the flow paths 22, 22 on the upper and lower surfaces of the flow paths 22 and 22 to impart a flow resistance to the hydraulic fluid to generate a damping force. 23, 23 are attached. The disc valves 23, 23 and the flow paths 22, 22 constitute the damping force generating means 100. Further, the shaft passage portion 10a, the notch 13, the passage portions 14 and 14, and the fixed orifices 15 to 18 constitute a bypass passage 102. Furthermore, the piston body 19 is the cylinder 1
An upper liquid chamber 24 and a lower liquid chamber 25 are separated from each other while sliding in the inside in the axial direction.

In the figure, reference numeral 28 denotes an angle setter for selecting the angle at which the adjuster 9 should be rotated by adjusting a scale or the like, to which one input terminal of a comparator 29 and a controller 30 are sequentially connected. There is. The output circuit of the position detector 7 is connected to the other input terminal of the comparator 29 via three lead wires 34a, 34b, 34c, and the lead wire 35 is connected to the output side of the controller 30. The motor 4 is connected via. The position detector 7, the angle setter 28, the comparator 29, and the controller 30 constitute control means.

Next, this operation will be described.

First, when the angle setter 28 is set to the zero scale, the motor 4 rotates, the adjuster 9 rotates via the output shaft 6 of the reduction gear unit 5, and all the fixed orifices 15 to 18 are closed. ing. Next, the scale is set by operating the angle setter 28 so as to obtain a desired damping force, for example, by selecting the state shown in FIG. At this time, since zero scale data in which all of the fixed orifices 15 to 18 are closed is output from the position detector 7 to the comparator 29,
The two input signals supplied to the comparator 29 do not match, for example, a signal corresponding to the difference in the input signal levels is input to the controller 30, and the controller 30 outputs a predetermined motor drive current to the motor 4. To do. Therefore, the motor 4 rotates by a predetermined amount, and the adjuster 9 is rotated through the output shaft 6 by a predetermined angle, that is, by the scale setting, and the state shown in FIG. 2 is obtained. That is, the passage portions 14 and 14 are in open communication with the fixed orifices 16 and 17. At this time, the position detector 7 outputs the position data of the rotation angle of the adjuster 9 to the comparator 29, and the position data matches the angle setting data from the angle setter 28 and is input to the comparator 29. The input signal level deviation is zero, the supply of the motor drive current from the controller 30 to the motor 4 is cut off,
The motor 4 stops. As a result, the fixed orifice 16,
The upper liquid chamber 24 and the lower liquid chamber 25 communicate with each other via 17,
The fixed orifices 16 and 17 are the disk valves 2
The desired damping force will be obtained in cooperation with each of 3,3.

Further, since the motor 4 is provided in the piston rod 2, even if a driving noise is generated when the motor 4 is driven, the noise does not leak to the outside and is not transmitted to the vehicle interior. Also, it is not exposed to mud or rain while driving.

Moreover, since the motor 4 is positioned and fixed in the rod hollow portion 3 by the retainer 8, it is stably and reliably supported in the rod hollow portion 3. Also, the output shaft 6
Is connected to the adjuster 9 via the short retainer 8, the output shaft 6 can be made as short as possible, and the adjuster 9 is rotated instead of directly opening and closing the bypass passage 102. Therefore, the shaft diameter can be sufficiently reduced. As a result, the weight of the output shaft 6 can be reduced. Therefore, it is not necessary to consider the friction torque between the output shaft and the piston rod 2, the torsional friction torque of the output shaft itself, and the generation of a large inertial force due to weight reduction as in the conventional case. Further, there is no sliding resistance between the output shaft 6 and the insertion hole of the retainer 8. Therefore, the drive torque of the motor 4 can be reduced by that much, the motor 4 can be downsized, and the rotation control accuracy of the adjuster 9 can be improved.

FIG. 3 shows another embodiment of the present invention. This uses a step motor 4A instead of the motor 4.
The step motor 4A has a short output shaft 31 connected to the adjuster 9, three or more stators are provided with three-phase windings, and each one of them is sequentially excited by an input pulse. Each time, the short motor output shaft 31 is rotated by a fixed angle (1 step). Therefore, the reduction gear unit 5 and the position detector 7 are omitted, and a predetermined number of pulses are generated from the pulse generator 32 by the angle scale setting by the angle setter 28A to rotate the step motor 4A stepwise. Thus, the motor output shaft 31 rotates by a certain angle, and the adjuster 9 can be positioned in the state shown in FIG.

Further, in this embodiment, since the reduction gear unit 5 is omitted and the output shaft 31 of the step motor 4A is directly connected to the adjuster 9, the length of the output shaft 31 can be further shortened. . Therefore, the torsional torque of the output shaft 31 is further reduced, and the step motor 4A is further downsized.

The present invention can be applied to both a two-cylinder type and a single-cylinder type hydraulic shock absorber, and a general oil liquid or a highly viscous oil liquid can be used as the working fluid in the cylinder 1.

EFFECTS OF THE INVENTION As described above, according to the present invention, by rotating the adjuster with the motor, the damping force adjustment by the adjuster can be controlled in multiple stages, and the motor is provided on the piston rod. Since it is housed in the hollow part of the rod, the upper space of the piston rod becomes large like a normal hydraulic shock absorber without a damping force variable mechanism,
It can be used for other purposes and the degree of freedom of layout on the vehicle is improved.

Moreover, since the motor is stably and securely supported by the retainer in the hollow portion of the rod, and the output shaft of the motor is connected to the adjuster through the insertion hole of the retainer to rotate, the length of the output shaft is increased. Can be made as short as possible and the shaft diameter can be made small. As a result, the weight of the output shaft can be reduced. Therefore, it is not necessary to consider the friction torque between the output shaft and the piston rod, the torsional friction torque of the output shaft itself, and the generation of a large inertial force as in the conventional case. Therefore, the drive torque of the motor can be reduced by that much, the motor can be downsized, and the control accuracy of the rotational position of the adjuster is improved.

Further, there is no need to attach a motor or the like after attaching the piston rod to the vehicle body, so that the attaching workability is improved and the shape of the vehicle body is not restricted. Furthermore, since the motor is shielded from the outside and protected, there is no risk of damage or deterioration of the motor, and the operating noise is double or triple shielded by the piston rod itself and the hydraulic fluid or cylinder. It is attenuated to sufficiently prevent radiation to the outside.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a hydraulic shock absorber of the present invention,
2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is a sectional view showing another embodiment of the present invention. 1 ... Cylinder, 2 ... Piston rod, 2a ... Through hole, 3
... Rod hollow part, 4, 4A ... Motor, 6, 31 ... Output shaft, 8 ... Retainer, insertion hole ... 8a, 9 ... Adjuster, 1
0 ... Cylindrical member, 19 ... Piston body, 24 ... Upper liquid chamber, 25 ... Lower liquid chamber, 100 ... Damping force generating means, 102
… Bypass passage.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-55-65741 (JP, A) Actually opened 55-109008 (JP, U) Actually opened 56-111009 (JP, U)

Claims (1)

[Claims] Claim: What is claimed is: 1. A cylinder filled with hydraulic fluid, a piston rod that is inserted into one end of the cylinder so as to be able to move forward and backward, and has a hollow rod portion in the axial direction of the inner end, and a cylinder at one end of the piston rod. Arranged through the member,
A piston body slidably accommodated while defining the inside of the cylinder into an upper liquid chamber and a lower liquid chamber, and a flow path provided in the piston body and connecting the upper liquid chamber and the lower liquid chamber. Damping force generating means for generating a damping force by giving flow resistance to the hydraulic fluid that substitutes and flows, a bypass passage formed in the tubular member for bypassing the flow passage, and a passage cross-sectional area of the bypass passage. Is a hydraulic shock absorber including an adjuster that adjusts the generated damping force by changing the position of the rod hollow according to the rotational position of the adjuster, and a motor that rotationally drives the adjuster based on a control signal of a control means. A tubular member for rotatably housing the adjuster is fixed to the opening end side of the portion, and a short cylindrical retainer is fixed to the upper end of the tubular member in the hollow rod portion. To the above A hydraulic shock absorber, characterized in that the motor and the adjuster are connected by an output shaft that positions and fixes the motor and that is inserted through an insertion hole that is formed through the retainer in the axial direction of the retainer.