JP2936004B2 - Vehicle hydraulic shock absorber with vehicle height adjustment device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vehicle hydraulic shock absorber provided with a vehicle height adjusting device.

[Conventional technology and problems to be solved]

The motorcycle height adjusting device described in Japanese Patent Application Laid-Open No. 55-79776 is provided at an end of a piston rod protruding from a piston slidably fitted in a damper cylinder. That is, a jack piston is fixed to the tip of the piston rod, this jack piston is slidably fitted in the jack cylinder, the upper and lower chambers are partitioned by the jack piston, and oil is supplied to and discharged from the jack cylinder. There are two ports. For this reason, two hydraulic pipes are required, so that the piping space is also required twice, which is complicated when the pipeline to the hydraulic power source is long. In particular, when there are two pipes on the left and right as in a front fork of a motorcycle, a total of four pipes are required, which is extremely complicated. In the case of a jack cylinder having two ports, a switching valve for selecting and switching one pipe to a hydraulic pressure source and the other pipe to a reverser tank becomes large, and a large space is required. As described above, since the number of pipes and the size of the switching valve are required, the cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle hydraulic shock absorber having a vehicle height adjusting jack unit having a structure capable of reducing the number of complicated pipes and reducing the size of the switching valve.

[Means for solving the problem]

In order to solve the above problems, a vehicle hydraulic shock absorber according to the present invention is provided with a mechanism for generating a damping force in a damper cylinder mounted on one of a vehicle body side and an axle side of a vehicle, and a piston rod extending outside the cylinder. A jack cylinder is attached to the other end of the vehicle body or the axle side, and a jack cylinder is attached to the other end of the jack piston.The jack piston is slidably and sealingly fitted in the jack cylinder. By forming orifice holes communicating the upper and lower chambers and supplying and discharging hydraulic oil between the external pressure source and one chamber in the jack cylinder, the jack piston and the piston rod connected thereto are Vehicle hydraulics equipped with a vehicle height adjusting device in which the other member attached to the vehicle body side or the axle side is formed to be displaceable. In 衝器, the orifice holes formed in the jack piston, damping force generated by the jack piston, characterized in that formed in a size that is larger than the damping force generated in the damper cylinder.

If the damping force generated in the orifice of the jack piston is made larger than the damping force generated in the damper cylinder, it is convenient for the reason described later.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 is a sectional view showing the vertical distribution of one of the front forks 20 of a motorcycle including a vehicle height adjusting jack unit according to the present invention. An outer cylinder 22 outside the inner cylinder 21 is slidably fitted, and a bottom of the inner cylinder 21 and a piston rod 23
A suspension spring 27 is interposed between a spring collar seat 24 and a spring receiver 26 fixed via a spring collar 25. The piston 29 attached to the lower end of the piston rod 23 is slidably fitted in a damper cylinder 28 extending upward from the bottom of the inner cylinder 21. A rod 30 is connected to an end of the piston rod 23 projecting upward through the upper end of the damper cylinder 28 by a screw.

On the other hand, a jack unit 40 of the present invention, which constitutes a part of the vehicle height adjusting device, is attached to the upper end of the outer cylinder 22. The jack unit 40 has a jack cylinder head cover 41 inserted in a sealed state until it contacts the shoulder 31 in the upper end opening of the outer cylinder 22, and the outer cylinder until it contacts the upward step 42 of the jack cylinder head cover 41. And an annular fork bolt 43 screwed into 22 female threads. A union bolt 44 'is screwed into an upper portion of the jack cylinder head cover 41, and a fitting 44 for pipe connection is connected to an outer periphery of the union bolt via upper and lower copper packings. The jack cylinder that constitutes the jack unit 40 is located below the jack cylinder head cover 41.
45 is screwed in and fixed by a nut 46. A jack piston 48 fixed to the upper end of the rod 30 is slidably fitted in the jack cylinder 45, and an end piece 49 is fixed to the lower end of the jack cylinder 45. It is preferable that the through hole of the jack piston 48 is larger because the vehicle height adjustment time is shorter when the vehicle height is increased or decreased, but the through hole is formed as an orifice according to the present invention for the reason described later.

2 and 3, the rear cushion 50 for performing a pumping action, the rear cushion side jack unit 60, and the front fork side jack unit 40 according to the present invention are connected to each other via a vehicle height adjusting switching valve. 1 shows a vehicle height adjustment circuit of a two-wheeled vehicle when the vehicle height is increased and when the vehicle height is decreased.

The rear cushion 50 includes a cylinder 51, a piston 52 slidably mounted in the cylinder, and a piston rod 53 projecting downward from the piston. A suspension spring 56 is stretched between a spring receiver 54 provided on the cylinder side and a spring receiver 55 provided on the cylinder end.

The jack unit 60 provided on the upper part of the rear cushion 50 includes a plunger case 61 fixed to the outer periphery of the cylinder 51, and an annular plunger 62 slidably fitted between the plunger case and the cylinder 51. A spring receiver 55 is provided at an end of the ring 63 of the plunger 62 that protrudes from the plunger case 61.

The chamber A in the cylinder of the rear cushion 50 forms a pump chamber. On the one hand, the pump chamber A is connected to the compression-side damping-force generating valve mechanism 66 by an oil passage 65 and the other is connected to the pump chamber A by an oil passage 67. It communicates with a first check valve 68 arranged in a direction for preventing the flow of hydraulic oil to the reservoir D. On the lower end side of the valve mechanism 66, a rotatable vehicle height adjustment switching valve 69 is provided, and on the outer periphery of this switching valve, a groove formed eccentrically from the outer periphery and formed in a peripheral surface of about 180 ° or more is provided. And the other oil path orthogonal to the orbit oil path, one end of which is opened in the orbit groove, and the other end of which is opened on the outer periphery of the switching valve. A second check valve 70 is urged by a spring in the other oil passage in a direction for preventing the flow of oil from the circumferential groove direction. Switching valve 69
A tappet 71 (FIG. 2a) having a penetrating oil passage 71a abuts against the peripheral surface of the eccentric cam-shaped portion of FIG.
A third check valve 72 is urged toward a valve seat 73 by a spring downstream of the valve. In the vehicle height down position shown in FIG. 2, the tappet 71 is pushed up by the switching valve 69 to move the third check valve 72 away from the valve seat 73, whereas in the vehicle height up position shown in FIG. 3, the tappet 71 is eccentric. The third check valve 72 is seated on the valve seat 73 because it is retracted by the concave peripheral surface of the cam-shaped portion.

Downstream of the third check valve 72, on the one hand, an oil passage 74 opens through a pipe joint 75 to an oil chamber C of the vehicle height adjusting jack unit 40 of the front fork 20, and on the other hand, an oil passage 76
Thus, the rear cushion 50 is opened to the oil chamber B of the jack unit 60. Further, an oil passage 90 communicating with an oil storage chamber D formed in the oil tank 69 is formed on the outer periphery of the switching valve 69, and the oil passage 90 is closed by a relief spring 91 in the middle of the oil passage 90. Directionally biased relief valve 77
Is interposed. Further, a blow valve 78 is interposed in a branch passage communicating from the oil passage 74 to the oil reservoir D. The oil chamber D of the oil tank 79 is adjacent to the gas chamber E via a slidable partition.

The vehicle height adjustment will be briefly described by this vehicle height adjustment hydraulic circuit. When traveling in an urban area, the vehicle height adjustment switching valve 69 is rotated to switch to the vehicle height down position shown in FIG. During traveling, the pressure oil sent from the pump chamber A during the compression stroke of the rear cushion 50 flows through the oil passage 65, but since the oil passage is closed by the second check valve 70 of the switching valve 69, the oil passage
The oil flows into the oil reservoir D of the oil tank 79 via 80. The gas chamber E performs volume compensation accompanying the intrusion of the piston rod 53. During the extension stroke, the oil corresponding to the volume from which the piston rod 53 has been drawn flows into the pump chamber A from the oil reservoir D via the oil passage 67.

When the changeover valve 69 is switched to the vehicle height increasing position when the vehicle enters a rough terrain, the pressure oil from the pump chamber A pushes up the third check valve 72 of the changeover valve 69 to flow during the compression stroke of the rear cushion 50. , And flows into the jack chambers B and C of the rear cushion 50 and the front fork 20 via the oil passages 76 and 74, respectively. During the extension stroke of the rear cushion 50, the pressure in the pump chamber A is reduced by the retreat of the piston rod 53 to the outside of the cylinder 51, so that the third check valve 72 of the switching valve 69 is sucked and closed, but the upstream of the oil tank 79 is closed. Since the first check valve 68 is opened, the oil in the oil reservoir D of the oil tank flows into the pump chamber A and the piston rod
Refill 53 intrusion volumes of oil. By repeating the compression and extension strokes of the rear cushion 50 as described above, a self-pumping action is performed, and oil is guided to the respective jack chambers B and C for each compression stroke to compress the respective suspension springs 56 and 27. Go on. The body is balanced by suspension springs, so each jack piston
63 and 48 compress the suspension springs 56 and 27, thereby increasing the suspension spring load and pushing up the vehicle body, thereby increasing the vehicle height.

However, as described above, if the diameter of the communication hole 47 of the jack piston 48 of the front fork-side jack unit 40 is large, the following inconvenience occurs. That is, the second
At the time of setting the vehicle height down as shown in the figure, if the two-wheeled vehicle jumps or the hydraulic shock absorber suddenly extends after passing through the protrusion, the upper and lower chambers of the piston 29 in the damper cylinder 28 of the front fork 20 A damping force proportional to the extension speed of the piston 29 is generated by a valve mechanism disposed in the oil hole of the piston 29, and a force for pulling the piston rod 30 downward acts, thereby moving the piston rod 30 to a jack cylinder 45 for adjusting the vehicle height. Pull in the direction of egress from inside as indicated by the arrow. At this time, since the upstream oil passage leading to the chamber above the jack piston 48 of the jack cylinder 45 is closed by the second check valve 70, the oil equivalent to the volume of the piston rod 30 withdrawing from the jack cylinder 45 is Although not replenished, if a tensile force greater than the atmospheric pressure of about 1 kg / cm ² × jack piston rod 30 is applied to piston rod 30,
The inside of the jack cylinder 45 becomes negative pressure, and the piston rod 30
Is easily removed from the inside of the jack cylinder 45. Also, when the piston 29 in the damper cylinder 28 is intensely extended such that the piston 29 abuts on the rebound spring 32 provided at the upper end of the damper cylinder 28, the force of unsprung weight × acceleration is applied to the piston rod.
The force pulling down 30 increases sharply and the piston rod
30 easily exits from the jack cylinder 45.
Thus, the front fork 20 is in the vehicle height-up state despite being set in the vehicle height-down state.

When the front fork 20 shifts from the extended state to the compression stroke, a force for pushing the jack piston 48 upward acts on the piston rod 30, and the piston rod
The 30 compensates for the negative pressure in the jack cylinder 45 and easily penetrates into the jack cylinder 45 to recover the vehicle height reduced state. In this way, when the vehicle jumps or passes over a protrusion in the vehicle height down setting state, the front fork becomes longer or shorter and becomes unstable, resulting in reduced steering stability. I do.

However, in the jack piston 48 of the present invention, a communication hole 47 for communicating the upper and lower chambers of the piston in the jack cylinder 45 is formed as an orifice, and the damper cylinder 28
The hydraulic fluid in the chamber below the jack piston 48 is throttled by the orifice 47 in response to the downward pulling force of the piston rod 30, and the piston rod Prevents downward displacement of 30. In this case, since the damping force generated in the orifice hole 47 depends on the speed, the chamber below the jack piston 48 is almost oil-locked against a sudden displacement of the piston rod 30, but the displacement is prevented. Piston rod 30
Since no damping force is generated for the slow speed displacement, the vehicle height can be increased.

Conversely, when the vehicle height is set, if the front fork 20 is compressed due to the two-wheeled vehicle jumping and landing from the air or jumping over the protrusion, the piston 29 in the damper cylinder 28 Is applied with a damping force at the time of compression generated by a compression side damping force generating mechanism of the piston portion.
In the case of a hydraulic shock absorber that receives a load when the hydraulic shock absorber is bottomed by the piston rod 30, the piston rod 30
When this load is applied, a force acts to cause the piston rod 30 to enter the jack cylinder 45. At this time, since the upstream oil passage leading to the chamber above the piston 48 in the jack cylinder 45 is closed by the third check valve 72, when the communication hole 47 in the upper and lower chambers of the jack piston 48 is large, The cross-sectional area of the piston rod 30 x the force that pushes up the piston rod acts on the hydraulic oil in the jack cylinder 45 to compress the hydraulic oil, but the hydraulic oil is incompressible and prevents upward displacement of the piston rod 30 Is done. However,
Also in this case, when the pushing-up force acting on the piston rod 30 is large as in the case of the bottom of the hydraulic shock absorber, a phenomenon occurs in which the piping hose is expanded and the piston rod 30 is displaced by that amount.

However, in the present invention, since the communication holes 47 in the upper and lower chambers of the jack piston 48 are formed as orifices, the communication holes generate a large damping force, and can suppress the instantaneous rise of the jack piston 48. . Since the damping force generated at the orifice 47 of the jack piston 48 depends on the speed, the hydraulic oil does not show a large resistance to the discharge flow rate of the hydraulic oil generated by the pumping action of the rear cushion 50. It can easily flow into the chamber below 48.

Next, modified examples of various hydraulic shock absorbers having the jack unit of the present invention are shown in FIG. 4 to FIG.

FIGS. 4 to 8 show an example in which the jack unit of the present invention is applied to a front fork of a motorcycle, and the same reference numerals as those in FIG. 1 are added with 100, 200, 300, 400, and 500. Is attached. 140, 240, 340, 440 and 540 are jack units of the present invention. FIGS. 4 and 5 show the jack unit and the damper cylinder in an opposite relationship to each other. FIG. 6 shows that the outer cylinder and the inner cylinder are the fourth,
5, the relationship between the jack unit and the damper cylinder is the same. In FIG. 7, the relationship between the jack unit and the damper cylinder is opposite to that in FIG. FIGS. 9 and 10 show examples in which the jack unit of the present invention is applied to a rear cushion, and similar parts are denoted by reference numerals obtained by adding 600 and 700, respectively. In both cases, the jack cylinder is mounted on the wheel side of the motorcycle. In FIG. 9, the spring receiver 654 is fixed to the piston rod 653, whereas in FIG.
54 is fixed to the jack cylinder 745.

〔The invention's effect〕

According to the present invention, in a hydraulic shock absorber provided with a jack unit for adjusting a vehicle height on a side of a piston rod that slides inside a damper cylinder and extends outside the cylinder, piping is performed by adopting a one-port hydraulic cylinder for the jack cylinder. And the size of the switching valve can be reduced.
Since the communication hole of the jack piston that connects the upper and lower chambers in the jack cylinder is formed as an orifice, as described above, the hydraulic shock absorber of the vehicle suddenly extends when the vehicle height is set down or the hydraulic shock absorber increases when the vehicle height is set. When the orifice is suddenly compressed, the orifice communication hole generates a large damping force and prevents the jack piston, and therefore the piston rod, from instantaneously descending or rising, and as a result, when the jack piston communication hole is large. The unstable expansion and contraction of the hydraulic shock absorber that occurs is eliminated, and a stable state is maintained. In addition, since the damping force generated at the orifice of the jack piston depends on the speed, during normal vehicle height adjustment, damping force is generated for the slow speed of the piston rod caused by hydraulic oil generated by pumping action. Therefore, the hydraulic oil can flow through the orifice without resistance, and there is no problem even if the communication hole is formed in the orifice.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a longitudinal half of a front fork of a motorcycle provided with a jack unit for adjusting the vehicle height according to the present invention, and FIG. 2 is a schematic diagram of a vehicle height adjusting circuit when the vehicle height is set to be reduced. FIG. 2a is a perspective view of a tappet as a component of the vehicle height up / down switching valve mechanism, FIG. 3 is a schematic diagram of a vehicle height adjustment circuit of a motorcycle when the vehicle height is increased, and FIGS. 4 to 10 are the present invention. It is a schematic longitudinal cross-sectional view which shows the modification which applied the jack unit of this invention to various hydraulic shock absorbers. 28 …… Damper cylinder, 23,30 …… Piston rod, 4
0 ... jack unit, 45 ... jack cylinder, 47
…… orifice, 48 …… jack piston

Claims (1)

(57) [Claims] 1. A damper cylinder mounted on one of a vehicle body side and an axle side of a vehicle is provided with a mechanism for generating a damping force, and a jack piston is mounted on an end of a piston rod extending outside the cylinder. The jack piston is slidably and sealingly fitted in the jack cylinder, and orifice holes communicating the upper and lower chambers are formed in the jack piston. By supplying and discharging hydraulic oil between the pressure source and one chamber in the jack cylinder, the other member attached to the vehicle body or axle can be displaced with respect to the jack piston and the piston rod connected to it. An orifice formed in a jack piston in a vehicle hydraulic shock absorber having a vehicle height adjusting device formed in Holes and damping force generated by the jack piston, a hydraulic shock absorber for a vehicle having a vehicle height adjustment device, characterized in that formed in a size that is larger than the damping force generated in the damper cylinder.