JPH07197975A - Damping force generator for vehicle hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To enhance only pressure side damping force characteristics for the later half of a middle speed range over to a high speed range up to each desired value in a state that pressure side clamping force characteristics from a low speed range to the first half of a middle speed range for a vehicular hydraulic shock absorber are kept at each desired value. CONSTITUTION:Bulkhead members 45 and 45a are provided while being faced to a piston 25, a base valve mechanism 36 or the pressure side main oil paths 29 and 38 of both the aforesaid piston and base valve. The bulkhead members 45 and 45a are provided with control oil paths 48 and 48a keeping the pressure side main oil paths 29 and 38 in a series condition, and with control valves 49 and 49a which behave toward the sides of the control oil paths 48 and 48a when a flow rate of operating oil flowing in the pressure side oil paths 29 and 38 exceeds a set value. And in addition to the above, limit passages 47 and 47a are provided, which secure a limit flow of operating oil at the action ends of the control valves 49 and 49a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force generator for a hydraulic shock absorber used in a suspension system of a traveling vehicle such as a motorcycle or an automobile.

[0002]

2. Description of the Related Art FIG. 9 of the accompanying drawings shows an example of a damping force generating device for a front fork that has been generally used as a front wheel suspension device for a motorcycle. Inner tube 2 for supporting the front wheel with the outer tube 20 connected to the
1 is inserted and removed freely.

A cylinder 22 stands upward from the lower bottom of the inner tube 21, and a seal cap 23 for sealing the upper end of the cylinder 22 and the outer tube 2.
A coil spring 24 for suspension is interposed between the upper end of 0 (this portion is not shown) and the restoring force of the coil spring 24 elastically supports the vehicle body on the wheel side.

A piston 25 is slidably inserted in the cylinder 22, and the piston 25 causes the cylinder 22 to slide.
The inside is divided into an upper hydraulic oil chamber A and a lower hydraulic oil chamber B, and the inside of the outer tube 20 and the inner tube 21 excluding the inside of the cylinder 22 serves as a reservoir chamber C.

The piston 25 is supported by a holding member 26. From the holding member 26, a piston rod 27 extends upward through a seal cap 23 of a cylinder 22, and an upper end of the piston rod 27 has an outer tube 20. Is attached to the upper end of the.

The piston 25 is provided with an expansion side main oil passage 28 during the expansion stroke and a compression side main oil passage 29 during the compression stroke, and the lower end outlet side of the expansion side main oil passage 28 is for generating the expansion side damping force. It is closed by a leaf valve 30, and the upper end outlet side of the pressure side main oil passage 29 is covered with a check valve 31 that opens toward the upper hydraulic oil chamber A.

These expansion side and compression side main oil passages 28, 2
A bypass oil passage 32 (a communicating portion to the reservoir chamber C is not shown) is provided in parallel with the holding member 26 and the piston rod 27 in parallel with 9, and communicates from the upper working oil chamber A to the reservoir chamber C side. In the middle of the bypass oil passage 32, a needle valve 35 that forms a variable orifice 34 that can be adjusted from the outside through a hollow operation rod 33 that is inserted into the piston rod 27 is provided.

On the other hand, a base valve mechanism 36 that seals the lower end of the cylinder 22 is disposed in the lower bottom portion of the cylinder 22 so as to face the piston 25, and a valve member 39 is attached to the base valve mechanism 36. It is fixed and attached.

The valve member 39 has a main oil passage 37 on the expansion side.
And the pressure side main oil passage 38 are respectively bored, the upper end outlet side of the extension side main oil passage 37 is covered with a check valve 40 which opens toward the lower hydraulic oil chamber B side, and the pressure side main oil passage 38 is provided. The outlet side of the lower end of the passage 38 is closed by a leaf valve 41 for generating a compression side damping force.

Further, in the base valve mechanism 36, like the piston 25, the expansion side and compression side main oil passages 37,
A bypass oil passage 42 communicating from the lower hydraulic oil chamber B to the reservoir chamber C side is provided in parallel with 38, and a needle valve 44 for forming a variable orifice 43 that can be adjusted from the outside is provided in the middle of the bypass oil passage 42. I am doing it.

As a result, during the extension stroke of the front fork, the flow resistance imparted by the variable orifice 34 to the hydraulic oil pushed out from the upper hydraulic oil chamber A to the reservoir chamber C through the bypass oil passage 32 and the piston 25 are increased. A leaf valve 30 for generating the extension-side damping force is pushed open from the extension-side main oil passage 28, and an extension-side damping force is generated by the flow resistance given by the leaf valve 30 to the hydraulic oil pushed out to the lower hydraulic oil chamber B. .

At this time, in the lower hydraulic oil chamber B,
The hydraulic oil is replenished from the reservoir chamber C while pushing the check valve 40 open through the expansion side main oil passage 37 of the valve member 39 in the base valve mechanism 36.

On the other hand, during the compression stroke of the front fork, the working oil in the lower working oil chamber B is supplied from the pressure side main oil passage 29 of the piston 25 to the upper working oil chamber A by opening the check valve 31. .

In parallel with this, the piston rod 2
7 is pushed out into the reservoir chamber C through the bypass oil passage 42 of the base valve mechanism 36, and the variable orifice 4 is supplied to the flow of this working oil.
The flow resistance provided by 3 and the leaf valve 41 for the hydraulic oil pushed from the lower hydraulic oil chamber B into the reservoir chamber C while opening the leaf valve 41 for generating the compression side damping force through the pressure side main oil passage 38 of the valve member 39. The compression resistance is generated by the flow resistance given by.

FIG. 10 shows an example of a hydraulic shock absorber that is widely and generally used as a rear wheel suspension system for a motorcycle. The hydraulic shock absorber is positioned inside the cylinder 1 and is slidably inserted. A piston 2 is provided, and the interior of the cylinder 1 is divided into an upper hydraulic oil chamber A and a lower hydraulic oil chamber B by the piston 2.

A piston rod 4 extends outward from the piston 2 through a seal cap 3 for sealing the upper end of the cylinder 1, and a connecting member 5 to the vehicle body side is attached to the upper end of the piston rod 4.

Corresponding to the connecting member 5, the mounting eye 6 connected to the wheel side is integrally formed at the lower end of the cylinder 1, and the hydraulic shock absorber has the connecting member 5 and the mounting eye 6 as a unit.
Is mounted between the vehicle body side and the wheel side of the motorcycle.

Spring bearings 7 and 8 are attached to the outer circumferences of the cylinder 1 and the piston rod 4, respectively, and a coil spring 9 for suspension is interposed between the spring bearings 7 and 8. The restoring force of the coil spring 9 elastically supports the vehicle body on the wheel side.

The upper hydraulic oil chamber A and the lower hydraulic oil chamber B are filled with hydraulic oil, and the cylinder 1 is compensated for the volume fluctuation due to the temperature change of the hydraulic oil and during the expansion and compression strokes of the hydraulic shock absorber. A free piston 10 is slidably inserted into the lower hydraulic oil chamber B in order to compensate for the hydraulic oil equivalent to the volume of the piston rod 4 moving in and out, and the lower end of the lower hydraulic oil chamber B is The gas chamber C is divided into parts.

The piston 2 has an extension side main oil passage 11 during an expansion stroke and a compression side main oil passage 12 during a compression stroke.
And a lower end outlet side of the extension side main oil passage 11 is closed by a leaf valve 13 for generating an extension side damping force,
Similarly, the upper end outlet side of the compression side main oil passage 12 is closed by a leaf valve 14 for generating a compression side damping force.

Further, the expansion side and compression side main oil passages 1
A bypass oil passage 15 is provided in the piston rod 4 in parallel with the needle valves 1 and 12, and a needle valve that forms a variable orifice 18 that can be adjusted from the outside through an adjusting knob 16 and an operating rod 17 is provided in the bypass oil passage 15. 19 is interposed.

As a result, during the expansion stroke of the hydraulic shock absorber, the flow resistance given by the variable orifice 18 to the hydraulic oil pushed from the upper hydraulic oil chamber A through the bypass oil passage 15 to the lower hydraulic oil chamber B, and The expansion side damping force is generated by the flow resistance given by the leaf valve 13 to the hydraulic oil that is pushed out into the lower hydraulic oil chamber B while the leaf valve 13 for generating the expansion side damping force is opened from the expansion side main oil passage 11 of the piston 2. To occur.

On the other hand, during the compression stroke of the hydraulic shock absorber, the flow resistance given by the variable orifice 18 to the hydraulic oil pushed from the lower hydraulic oil chamber B to the upper hydraulic oil chamber A through the bypass oil passage 15 and the piston To generate a compression side damping force with the flow resistance given by the leaf valve 14 to the hydraulic oil pushed out into the upper hydraulic oil chamber A while pushing open the compression side damping force generating leaf valve 14 from the second compression side main oil passage 12. become.

In FIG. 10, the hydraulic shock absorber for suspending the rear wheel of the motorcycle has been described as an example. However, even in the shock absorber for an automobile, the damping force generating mechanism is basically different. There is no.

[0025]

As described above, in the conventional hydraulic shock absorbers for front forks and rear wheel suspensions in motorcycles, or shock absorbers for automobiles, the expansion side and compression side damping forces are reduced. It was designed to be generated by using a leaf valve in which valve-shaped valves are superposed.

Certainly, such a leaf valve is superior in that the expansion side and compression side damping forces can be set or changed by a relatively simple operation by selecting the number or diameter of the plate valves, but For vehicles that frequently jump, such as motorcycles for motocross and automobiles for stunts, the input received at the time of touchdown after the jump is extremely large. There is an inconvenience that the characteristics cannot be obtained.

That is, as indicated by the dotted line m in FIG.
When trying to obtain the compression side damping force characteristic that emphasizes the high-speed range where the expansion and contraction speed is high, the compression side damping force characteristic in the low and medium speed range becomes too large, which adversely affects the feeling. On the contrary, the dotted line n in FIG. When trying to obtain the compression side damping force characteristics that emphasized the low speed range to the middle speed range as above, this time, the compression side damping force characteristics from the latter half of the middle speed range to the high speed range were too small to jump. It may cause severe bottoming when receiving a large input, such as when touching the ground.

Therefore, the object of the present invention is to improve only the compression side damping force characteristic from the latter half of the medium speed range to the high speed range to a desired value without changing the compression side damping force characteristic in the first half of the low / medium speed range. It is an object of the present invention to provide an improved damping force generation device for a hydraulic shock absorber for a vehicle of this type.

[0029]

In the present invention, the partition member is provided so as to face the pressure side main oil passage of the piston or the base valve mechanism or both of them.

In addition, the partition member has a control oil passage which is kept in series with the pressure-side main oil passage, and is directed toward the control oil passage when the flow rate of the hydraulic oil flowing through the pressure-side main oil passage exceeds a set value. And a control valve that operates.

In addition to these, it is achieved by providing a restriction passage for ensuring a restricted flow of hydraulic oil at the operating end of the control valve.

[0032]

Thus, according to the present invention, for example, as in the first half of the low / medium speed range during the compression stroke of the hydraulic shock absorber,
The control valve does not move while the flow rate of the hydraulic oil flowing through the pressure side main oil passage is relatively small, so the control oil passage area of the bulkhead member is sufficiently secured, and therefore the pressure side damping force in the first half of the low / medium speed range is Similarly, it is generated by the leaf valve for generating the compression side damping force.

On the other hand, when the compression speed of the hydraulic shock absorber enters from the latter half of the middle speed range to the high speed range, the control valve moves to close the control oil passage in the partition wall member to the upper working oil chamber on the expansion side. Or the control oil passage itself is made a restricted passage by reducing the passage area of the control oil passage.

As a result, the rate of increase of the hydraulic oil pressure in the lower hydraulic oil chamber is increased, and the compression side damping force characteristic from the latter half of the medium speed range to the high speed range is enhanced.

That is, the preferable compression side damping force characteristic is shown by the solid line p in FIG.

[0036]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows an example in which the present invention is applied to the piston portion and the base valve mechanism portion of the conventional motorcycle front fork shown in FIG. 9, and other than the components described below. Since the parts are substantially the same as those in the case of FIG. 9, the same reference numerals as those in FIG.

In FIG. 1, a partition member 45 that divides the inside of the cylinder 22 into upper and lower parts with a leaf valve 30 for generating the expansion side damping force interposed is provided in the lower portion of the piston 25.
The partition member 45 is fixed to the holding member 26 by a piston nut 46 together with the piston 25 via a washer 53, a collar 54 and a spacer 58.

A recess 51 is formed on the lower surface of the partition member 45, and the recess 51 passes through the control oil passage 48 bored in the partition member 45 to form a chamber 57 between the piston 25 and the partition member 45.
It leads to.

Further, the outer periphery of the lower end flange 55 of the partition member 45 has a slight gap with the inner wall of the cylinder 22, and the partition member 45 is bypassed by this gap to lower hydraulic oil chamber B.
Forming a restricted passage 47 that directly communicates with the chamber 57.

Below the concave portion 51 of the partition wall member 45, a plate-shaped control valve 49 is arranged so as to be movable up and down along the collar 54 by forming a limiting flow passage 50 with the inner wall of the cylinder 22. A spring 52 is interposed between the control valve 49 and the bottom surface of the recess 51.

The control valve 49 is normally pressed against the upper surface of the washer 53 of the piston nut 46 by the restoring force of the spring 52. In this state, the control valve 49
Holds the opening area of the lower end opening of the recess 51 in the partition member 45 to the maximum.

Also, for the base valve mechanism 36,
A similar control valve 49a is provided.

That is, in the base valve mechanism 36, the partition wall member 45a which is located above the valve member 39 and divides the inside of the cylinder 22 into upper and lower parts is provided with the valve member 39 and the washer 5.
3a, the collar 54a, the stopper 40a of the check valve 40, and the spacer 58a, and the piston nut 46a.

In the partition member 45a, a plurality of lower control oil chambers B are formed at equal intervals by concentrically arranging axial control oil passages 48a communicating with the chamber 57a between the partition member 45a and the valve member 39. In addition, a recess 51a is formed on the upper surface of the partition member 45a.

The outer periphery of the partition member 45a has a slight gap with the inner wall of the cylinder 22, and the partition member 45a is bypassed by this gap so that the lower hydraulic oil chamber B is accommodated in the chamber 57.
A limiting passage 47a is formed directly to a.

Above the recess 51a of the partition member 45a,
A plate-shaped control valve 49a is provided movably up and down along the collar 54a by forming a restricted flow path 50a between the control valve 49a and the recess 5 and the inner wall of the cylinder 22.
A spring 52a is interposed between the bottom surface of the la and the bottom surface of the la.

The control valve 49a normally uses the washer 53a of the piston nut 46a by the restoring force of the spring 52a.
Is pressed against the lower surface of the control valve 49a in this state.
The maximum opening area is maintained.

Then, each of these control valves 4 described above
9, 49a from the lower hydraulic oil chamber B to the restriction flow path 5
The flow velocity of the hydraulic oil toward the upper hydraulic oil chamber A and the reservoir chamber C through 0, 50a exceeds a predetermined speed,
The initial load of the springs 52, 52a is set so that the flow resistance of 0, 50a does not move until the pressure difference acting on the upper and lower surfaces of the control valves 49, 49a exceeds a set value.

As a result, for example, while the flow velocity of the hydraulic oil flowing through the restriction flow passages 50, 50a is relatively slow, as in the first half of the low speed region to the middle speed region during the compression stroke of the front fork, the control valves 49, 49a are controlled. Does not move to secure a large opening area of the control oil passages 48, 48a in the partition members 45, 45a.

Therefore, the compression side damping force from the low speed region to the first half of the medium speed region is generated by the leaf valve 41 for generating the compression side damping force of the valve member 39 in the base valve mechanism 36, as in the conventional case.

On the other hand, when the compression speed of the front fork enters the latter half of the medium speed range, the flow velocity of the hydraulic oil from the lower hydraulic oil chamber B toward the upper hydraulic oil chamber A and the reservoir chamber C through the restriction flow passages 50 and 50a. Exceeding a predetermined speed, the restricted flow path 5
Due to the flow resistance of 0, 50a, the pressure difference acting on the upper and lower surfaces of the control valves 49, 49a rises above the set value.

Therefore, the control valve 49,
49a begins to move over the springs 52, 52a, narrows the opening area of the lower end opening of the recess 51 in the partition wall members 45, 45a and the opening area of the control oil passage 48a, and increases the compression speed due to their synergistic effect. Increase the rate of increase of the compression side damping force.

Further, when the compression speed of the front fork increases and enters the high speed range, the control valves 49, 49a are pressed against the partition members 45, 45a and the partition members 45, 45a.
The opening of the lower end of the recess 51 at a and the control oil passage 48a are closed.

As a result, on the piston 25 side,
Restriction passage 4 which is a gap between the partition member 49 and the cylinder 22
7, the hydraulic oil flows into the chamber 57, and also on the base valve mechanism 36 side, the hydraulic oil flows into the chamber 57a only through the restriction passage 47a which is the gap between the partition member 45a and the cylinder 22. The limiting flow of is kept to a minimum, and the synergistic action of the two maximizes the rate of increase of the compression side damping force in the high speed range of the front fork.

In this way, the control valves 49, 49a are
During the compression stroke of the front fork, the control operation is performed only from the latter half of the medium speed range to the high speed range. Thus, the compression side damping force characteristic of the front fork gradually changes from the latter half of the middle speed range as shown by the solid line p in FIG. As a result, the damping force on the compression side in the high speed range during large input action is significantly increased.

In the above embodiment, the control valve 49, the control valve 49, and the base valve mechanism 36 are provided in both the piston 22 and the base valve mechanism 36.
Although 49a is provided, it is needless to say that the same operation can be performed by providing only one of the two by appropriately designing the change amount of the oil passage area of the control flow portion.

FIG. 3 shows a modified example of the portion of the piston 25 in the front fork mentioned above. In the case of FIG. 1, the control oil is restricted after the control oil passage 48 is closed by the control valve 49. The flow is created by a restriction passage 47 which is a gap between the cylinder 22 and the partition member 45.

On the other hand, in the embodiment shown in FIG. 3, an oil passage 48 'having a vertical step is formed in the partition wall member 45 in parallel with the control oil passage 48, and the control valve 49 serves as the limiting oil passage 48. Oil passage 48 'is always in the lower hydraulic chamber B even when the
The chamber 57 is kept in communication.

A restricting member 56 is made to face the partition member 45 with a shim 59 between the opening of the oil passage 48 ′ toward the chamber 57 side, and the restricting member 56 allows the restricting member 56 to contact the partition member 45. A limiting passage 47c is formed according to the thickness of the shim 59.

As a result, when the control valve 49 operates to close the lower end opening of the control oil passage 48, the working oil from the lower working oil chamber B passes through the oil passage 48 'and the restriction passage 47c to form the chamber 57. Then, from here, the check valve 31 of the piston 25 is opened to face the upper hydraulic oil chamber A, and the increase rate of the compression side damping force in the high speed region of the front fork is maximized as in the case of the embodiment of FIG. To do.

As described above, the limiting member 56 may be constructed as a fixed member which always keeps a constant position with respect to the partition member 45. In particular, in the embodiment of FIG. By pressing the restricting member 56 against the shim 59 with the spring 60, the restricting member 56 is configured as a relief valve 56a.

As a result, as shown in FIG. 4, the high speed region of the front fork in which the flow of hydraulic oil from the lower hydraulic oil chamber B to the upper hydraulic oil chamber A is restricted by the restriction passage 47c (see FIG. 3). When the compression speed further increases, the relief valve 56a, which is the restricting member 56, causes the spring 6 to
It lifts against 0, and prevents the hydraulic pressure in the lower hydraulic chamber B from rising abnormally.

When it is not necessary to give the relief action to the restriction passage 47c, as described above, the restriction member 56 may be used as a fixing member to form the restriction passage 47c by the shim 59. However, the oil passage 48 ′ may be configured as a throttle hole without using the restriction member 56 and the shim 59, and the oil passage 48 ′ may directly configure the restriction passage 47 c.

FIG. 5 shows another structural example of the piston 25 part, and FIG. 6 shows another structural example of the base valve mechanism 36 part.

In the embodiments of FIGS. 5 and 6, the recesses 61, 61a are formed in the control surfaces of the partition members 45, 45a.
And the control valves 49, 61 are formed in the recesses 61, 61a.
By positioning 49a, the restricted flow paths 50, 50a are positively configured.

In addition to this, the restricted passages 47d, 47
e is constituted by the unclosed portion when the control valves 49, 49a move to the operating ends to close the control oil passages 48, 48a of the partition members 45, 45a.

In the modified examples of FIGS. 3, 5 and 6, the structure of the other parts is the same as that of the embodiment of FIG. 1 described above, and therefore, the explanation is given by using the same reference numerals. Omit it.

Even in the case of FIG. 3, FIG. 5 and FIG. 6, it is possible to significantly increase only the compression side generated damping force in the high speed range at the time of large input action, as in the case of FIG. Easy to understand based on the explanation.

Further, FIG. 7 shows an example in which the present invention is applied to the piston portion of the hydraulic shock absorber as the conventional rear wheel suspension system for a motorcycle shown in FIG. Since the other parts except for are exactly the same as those in the case of FIG. 10, only the piston part will be shown and described here.

Even in this case, various modifications can be made similarly to the above-mentioned front fork, but the case of having the same configuration as the embodiment of FIG. 5 which is one of them will be described. Therefore, other modified examples will be omitted because they can be easily understood based on the above description.

As described above, FIG. 7 shows an embodiment corresponding to FIG. 5 described above. Below the piston 2, the inside of the cylinder 1 is sandwiched with the leaf valve 13 for generating the expansion side damping force interposed therebetween. A partition member 45 which is divided into an upper part and a lower part is provided.
It is fixed to a.

An annular recess 61 is formed on the lower surface of the partition member 45, and the partition member 45 is axially penetrated from the annular recess 61 to connect the lower hydraulic oil chamber B to the piston 2 and the partition member 4.
A plurality of control oil passages 48 communicating with the chamber 57 between the five are provided concentrically and at equal intervals.

A plate-shaped control valve 49 is vertically movably disposed in the annular recess 61 of the partition member 45, and the outer peripheral surface of the control valve 49 and the inner peripheral surface of the annular recess 47 both serve as a control valve. A restricted flow path 50 is formed between them.

Another annular recess 51, which is deeper than the annular recess 61, is provided on the lower surface on the inner peripheral side of the annular recess 61. The annular recess 51 is located in the annular recess 51 and is located between the bottom surface and the control valve 49. A spring 52 is interposed in the.

The control valve 49 is usually the spring 5
It is pressed against the upper surface of the washer 53 of the piston nut 46 by the restoring force of 2. In this state, the control valve 49
Fully opens the lower end opening of the control oil passage 48 in the partition member 45.

The control valve 49 is controlled by the flow resistance of the restriction flow passage 50 when the flow velocity of the hydraulic oil from the lower hydraulic oil chamber B toward the upper hydraulic oil chamber A through the restriction flow passage 50 exceeds a predetermined speed. The initial load of the spring 52 is set so that it does not move until the pressure difference acting on the upper and lower surfaces of the valve 49 exceeds a set value.

As a result, the control valve 49 moves while the flow velocity of the hydraulic oil flowing through the restriction passage 50 is relatively low, for example, in the first half of the low speed region to the middle speed region during the compression stroke of the hydraulic shock absorber. Instead, the opening area of the control oil passage 48 in the partition member 45 is secured to be large. Therefore, the compression side damping force from the low speed region to the first half of the medium speed region is generated by the leaf valve 14 for generating the compression side damping force as in the conventional case. It will be.

On the other hand, when the compression speed of the hydraulic shock absorber enters the latter half of the medium speed range, the flow velocity of the hydraulic oil from the lower hydraulic oil chamber B toward the upper hydraulic oil chamber A through the restriction flow path 50 exceeds a predetermined speed. The pressure difference acting on the upper and lower surfaces of the control valve 49 rises above the set value due to the flow resistance of the restriction flow path 50.

Therefore, the control valve 49 is controlled by this pressure difference.
Begins to move by overcoming the spring 52, and the partition member 45
The opening area of the control oil passage 48 is narrowed and the increase rate of the compression side damping force is increased as the compression speed is increased.

Further, when the compression speed of the hydraulic shock absorber increases and enters the high speed range, the control valve 49 is pressed against the lower end opening of the control oil passage 48 in the partition member 45 as shown in FIG.

As a result, the hydraulic oil flowing from the lower hydraulic oil chamber B toward the chamber 57 flows only through the control passage 47f constituted by the unclosed portion of the control oil passage 48 by the control valve 49, and the hydraulic oil is restricted. Keep the flow to a minimum and maximize the rate of increase of the compression side damping force in the high speed range.

As described above, the control valve 49 performs the control operation only from the latter half of the middle speed range to the high speed range during the compression stroke of the hydraulic shock absorber, and thus the pressure side damping force characteristic of the hydraulic shock absorber is as shown in FIG. As indicated by a solid line p in FIG. 2, the compression side damping force in the high speed region during the large input action is greatly increased while gradually increasing from the latter half of the medium speed region.

[0084]

As described above, according to the invention of claim 1, the compression side damping force characteristic in the first half of the low / medium speed range is the same as that of the conventional one, and the compression side damping force from the latter half of the medium speed range to the high speed range. The rate of increase of the characteristic can be increased, and further, the rate of increase of the compression side damping force characteristic in a higher speed region can be maximized by the limiting passage which is set in advance.

From this fact, it becomes possible to effectively improve the riding comfort and secure the steering stability by effectively responding to a wide range of medium and high speeds.

According to the second aspect of the invention, while ensuring the above effect, the limiting passage for limiting the compression side damping force in a higher speed region can be easily utilized by utilizing the gap between the cylinder and the partition member. Can be created.

According to the invention of claim 3, as compared with the invention of claim 2, the passage area of the restricted passage can be maintained more accurately by a preset value regardless of the misalignment between the cylinder and the partition member. it can.

According to the fourth aspect of the present invention, it is possible to set the compression side damping force characteristic in a higher speed region in a preferable form by giving a relief action to the restricted passage to control the passage area. Become.

According to the fifth aspect of the invention, the unclosed portion of the control passage is utilized by the control valve without providing the control passage for limiting the compression side damping force in the higher speed region separately from the control oil passage. Then you can easily give.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional front view of essential parts in which the present invention is applied to a damping force generating mechanism portion of a front fork for a motorcycle.

FIG. 2 is a graph showing compression side damping force characteristics according to the present invention.

FIG. 3 is a fragmentary longitudinal sectional view of a piston portion showing another embodiment of the present invention.

FIG. 4 is a fragmentary vertical sectional view showing an operating state of the same.

FIG. 5 is a fragmentary vertical sectional view of a piston portion showing still another embodiment of the present invention.

FIG. 6 is a fragmentary vertical sectional view showing another modified example of the base valve mechanism.

FIG. 7 is a longitudinal sectional partial view of a main part in which the present invention is applied to a piston portion of a hydraulic shock absorber or a vehicle shock absorber as a rear wheel suspension device in a motorcycle.

FIG. 8 is a fragmentary vertical sectional view showing an operating state of the same.

FIG. 9 is a vertical cross-sectional view showing a damping force generating mechanism portion of a conventionally known front fork for a motorcycle.

FIG. 10 is a partial vertical sectional front view of a hydraulic shock absorber as a rear wheel suspension device for a motorcycle that has been generally used in the past.

[Explanation of symbols]

2 piston 12 pressure side main oil passage 25 piston 29, 38 pressure side main oil passage 36 base valve mechanism 45, 45a partition wall member 47, 47a, 47b, 47c, 47d, 47e, 47
f, 48, 48a control oil passage 48 'oil passage 49, 49a control valve

Claims (5)

[Claims] 1. A partition wall member is provided to face a pressure side main oil passage of a piston or a base valve mechanism or both of them, and a control oil passage for keeping the partition member in series with the pressure side main oil passage, and the pressure side main oil passage. A control valve that operates toward the control oil passage side when the flow rate of the hydraulic oil flowing in the passage exceeds a set value, and a restriction passage that secures a limited flow of the hydraulic oil at the operating end of this control valve. A damping force generation device for a hydraulic shock absorber for a vehicle, comprising: 2. The damping force generating device for a hydraulic shock absorber for a vehicle according to claim 1, wherein the limiting passage is formed by an outer peripheral gap of the partition wall member. 3. The damping force generator for a hydraulic shock absorber for a vehicle according to claim 1, wherein the restriction passage is constituted by an oil passage provided in the partition wall member in parallel with the control oil passage. 4. The damping force generation of the hydraulic shock absorber for a vehicle according to claim 1, wherein the restriction passage is constituted by a relief valve arranged at an outlet portion of the oil passage provided in the partition wall member in parallel with the control oil passage. apparatus. 5. The damping force generating device for a hydraulic shock absorber for a vehicle according to claim 1, wherein the restriction passage is constituted by an unclosed portion of the control oil passage at the operating end of the control valve.