JP2905530B2 - Damping force adjustment mechanism - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a damping force adjusting mechanism for a vehicle damper.

(Prior Art) In order to prevent the sinking of the front wheels during braking of the vehicle and improve running stability, a relief valve is provided in a passage through which hydraulic oil flows when the damper is operated to the compression side, and the relief valve is set. There is known an anti-nose dive device that increases the pressure in accordance with the brake oil pressure to increase the pressure-side damping force during braking and to prevent the front-wheel-side damper from contracting (Japanese Patent Application Laid-Open No. 57-95281).

(Problems to be Solved by the Invention) In this case, the relief valve for adjusting the damping force includes a plunger responsive to the hydraulic pressure of the brake circuit, and the plunger moves by the hydraulic pressure to reduce the spring initial load of the relief valve. It is designed to increase.

Therefore, the set load of the relief valve increases during braking as compared with during normal running, and it is possible to suppress the damper from moving in the compression direction.

It should be noted that the type of oil used in the normal brake circuit and the type of oil used in the damper are different. For this reason, a seal is provided around the plunger of the relief valve to prevent leakage of the hydraulic oil.

However, when the set load of the spring of the relief valve is changed in accordance with the stroke amount of the plunger in this way, if an attempt is made to increase the adjustment range of the set load of the relief, the stroke amount of the plunger becomes large, and especially around the plunger. Due to the friction of the interposed seal, the responsiveness of the operation is deteriorated, and the hysteresis of the valve operating characteristics is large, so that there is a problem that it is difficult to adjust the damping force accurately with respect to the brake oil pressure.
Also, as shown in Japanese Patent Application Laid-Open No. 57-95281, normally, the damping valve has the same location where the operating pressure is received and the location where the hydraulic oil escapes, and the damping valve is pushed open to escape from there. I have. In such a structure, the amount of hydraulic oil that escapes increases when the area under pressure is increased. There is a problem that the pressure receiving area cannot be determined irrespective of the escaping amount of the hydraulic oil, and the opening of the damping valve cannot be set freely and finely.

An object of the present invention is to solve such a problem.

(Means for Solving the Problems) Accordingly, the present invention controls the opening and closing of a passage for allowing hydraulic oil to escape from an oil chamber to an oil storage chamber by a control pressure according to a vehicle running state when a damper is operated on a compression side or an extension side. In a damping force adjusting mechanism provided with a damping force adjusting valve, the damping force adjusting valve is provided on a bottomed cylindrical spool guide for closing a passage and on an outer peripheral surface of the spool guide and through which a hydraulic oil escapes to an oil reservoir. A bottomed cylindrical valve spool that fits on the outer surface of the spool guide to open and close the through hole, and that penetrates the center of the bottom of the spool guide and abuts on the inner bottom of the valve spool to operate the hydraulic pressure in the oil chamber. And a pressure chamber that applies a control pressure against the plunger to the valve spool, and a partition member that defines the pressure chamber as a passage for the hydraulic oil. Equipped.

(Operation) Therefore, the valve spool is urged in the valve closing direction according to the control pressure of the pressure chamber. When the hydraulic oil pressure acting on the plunger exceeds the valve closing force of the valve spool, the plunger is displaced and the valve spool opens.

The valve opening pressure of the valve spool is directly determined by the control pressure of the pressure chamber, and the control pressure does not change the initial position of the valve spool or the effective stroke amount. Characteristics can be adjusted.

(Embodiment) The embodiment shown in FIGS. 1 and 2 will be described.

FIG. 1 shows an overall configuration of a damper, and FIG. 2 shows an enlarged configuration of a damping force adjusting valve. In FIG. 1, a damper 1 has a piston 22 attached to a tip of a piston rod 21 inserted into a cylinder 20, The interior of the cylinder 20 has two oil chambers 23A,
23B.

An outer tube 24 is arranged concentrically outside the cylinder 20 and forms an annular oil reservoir 25 between the outer tube 24 and the cylinder 20.

The piston 22 has a check valve 26 that allows the flow of hydraulic oil only from the oil chamber 23B to the oil chamber 23A, and the bottom of the cylinder 20 has a flow of hydraulic oil only from the oil reservoir 25 to the oil chamber 23B. Check valve 27 is provided.

At the same time, an overload relief valve 28 is provided at the bottom of the cylinder 20 so that when the pressure in the oil chamber 23B becomes equal to or higher than a predetermined value, hydraulic oil is released to the oil reservoir 25.

On the other hand, a damping force adjustment valve 3 is provided in the middle of the passage 30 connecting the oil chamber 23A and the oil reservoir chamber 25, and generates a damping force for the compression side and the expansion side operation by imparting resistance to the flow of the hydraulic oil. Let it.

That is, when the piston 22 moves downward on the pressure side, the hydraulic oil in the oil chamber 23B to be compressed flows into the expanding oil chamber 23A via the check valve 26 of the piston 22, and further into the invading volume of the piston rod 21. The corresponding hydraulic oil flows out from the passage 30 into the oil reservoir 25, and when the piston 22 moves upward, the check valve 26 of the piston 22 is closed. Passage 3
The oil flows from 0 to the oil sump chamber 25, and the expanding oil chamber 23B is replenished with hydraulic oil from the oil sump chamber 25 via the check valve 27 at the bottom. On the other hand, the hydraulic oil is circulated to the oil reservoir 25 via the passage 30, and the damping force adjusting valve 3
A predetermined compression-side and extension-side damping force is generated in accordance with the set load (valve opening characteristic).

The passage 30 is connected to a passage 32 provided in a bearing portion 31 at an upper portion of the cylinder 20 and is formed as a pipe vertically penetrating the oil reservoir 25. The damping force adjusting valve 3 is attached from the outside of the outer tube. I have.

As is apparent from FIG. 2, the damping force adjusting valve 3 has an interior of a valve case 35 partitioned into an internal chamber 37 and an outer pressure chamber 38 by a bellows 36 as a partition member. Control pressure (oil pressure or air pressure) that changes according to the state
Is introduced.

As the control pressure, for controlling the attitude of the vehicle, for example, control pressure adjusted by a controller or the like by detecting these driving conditions so as to prevent sinking during braking or rolling during turning, or The brake circuit pressure or the like that increases during braking is directly introduced.

A spool guide 39 is disposed in the inner chamber 37, and a cylindrical valve spool having a bottom is provided outside the spool guide 39.
40 is slidably fitted, and the valve spool 40
A plunger 41 abutting on the inner bottom surface penetrates freely through the center of the spool guide 39.

At one end of the plunger 41, a spool guide 39 is formed, and hydraulic oil pressure is guided from a through hole 43 connected to the passage 30, and the plunger 41 pushes the valve spool 40 in the valve opening direction according to the pressure. . On the other hand, the control pressure of the pressure chamber 38 is applied to the other end of the valve spool 40 via the bellows 36, and together with the return spring 42, the plunger 41
Push back.

Therefore, the valve spool 40 is displaced in accordance with these pressure balances, and is separated from the seat portion 44 to form a through hole.
Hydraulic oil from 43 passes from passage 45 via internal chamber 37 to oil reservoir
It returns to 25, and the valve spool 40 at this time
A damping force is generated in accordance with the opening degree.

In FIG. 1, a gas chamber 48 partitioned by a free piston 47 is formed inside the piston rod 21, and the pressure of the oil chamber 23A is
9, the damping force adjusting valve 3 is closed and the free piston 47
Are displaced and absorb the impact.

 The configuration is as described above. Next, the operation will be described.

With the expansion and contraction of the piston rod 21, the hydraulic oil flows from the oil chamber 23A through the passage 30 in the oil reservoir 25
And returns from the oil storage chamber 25 to the oil chamber 23B.

Therefore, a damping force is generated on both the extension side and the compression side according to the resistance of the damping force adjusting valve 3 interposed in the passage 30.

When the control pressure guided to the pressure chamber 38 of the damping force adjusting valve 3 is low, the operating oil pressure for moving the plunger 41 is determined by the spring load of the return spring 42, and the generated damping force is in a minimum state.

For example, when emphasizing a soft ride, such as when driving in an urban area, the damping force can be adjusted to a minimum value by reducing the control pressure.

On the other hand, if the control pressure introduced into the pressure chamber 38 of the damping force adjusting valve 3 is increased, the pressure against the plunger 41 increases, and the hydraulic oil pressure required to push and open the valve spool 40 increases. .

As shown in FIG. 4, the valve opening pressure when the valve spool is displaced via the plunger 41 is determined by the control pressure Pv, and the generated damping force increases accordingly.

In this case, even if the control pressure of the pressure chamber 38 changes, the valve spool 40 is at the same position, and the valve is opened by slightly displacing the valve spool 40. The valve operation responsiveness is very good, and the set load (valve opening pressure) can be adjusted with high accuracy in accordance with the control pressure of the pressure chamber 38.

Further, since the pressure chamber 38 and the internal chamber 37 are partitioned by the bellows 36 and mixing of the hydraulic oil is completely prevented, the plunger 41 and the spool guide 39 or the spool guide 39
There is no need to provide a seal on the sliding part such as the valve spool 40, and the hysteresis of the valve opening characteristic is small because the sliding friction due to the seal or the like is small.

When the control pressure of the pressure chamber 38 is increased during turning or braking of the vehicle in this manner, the corresponding plunger 41
, Ie, the hydraulic oil pressure in the passage 30 can be immediately increased to increase the damping force, and it is possible to suppress a change in the attitude of the vehicle and the like with good response.

Next, the embodiment of FIG. 3 will be described. In this embodiment, a free piston 36A is provided as a partition member instead of the bellows 36. The free piston 36A is fixed to the inner periphery of the valve case by a snap ring 36C. The valve spool 40 slidably passes through the center hole 36B.

The pressure chamber 38 and the internal chamber 37 are defined by the free piston 36A to prevent mixing of hydraulic oil.

 In this case, the same operation as in the first embodiment can be obtained.

(Effects of the Invention) As described above, according to the present invention, the valve opening timing of the valve spool is directly determined by the plunger moved by the operating oil pressure of the oil chamber and the control pressure corresponding to the vehicle running state opposed thereto. Therefore, the initial position of the valve spool, the effective stroke amount, and the like are not changed by the control pressure, and the valve opening pressure characteristics can be adjusted with good responsiveness to the control pressure and with high accuracy. In addition, since the operating pressure is not applied directly to the valve spool that opens and closes the through hole, the operating pressure is applied to the plunger.By changing the area ratio between the plunger and the valve spool, the valve opening pressure relative to the control pressure can be freely adjusted. It can be easily set. Furthermore, since the movement of the plunger and valve spool is guided by the spool guide,
There is no inclination, the operation is good, and stable characteristics can be obtained. In addition, since the operating oil is separated by the partition member, there is no need to seal the sliding part of the plunger or valve spool, and there is no hysteresis in the operating characteristics due to seal friction, so that accurate valve opening characteristics can always be obtained for control pressure. it can.

[Brief description of the drawings]

1 is an overall sectional view showing an embodiment of the present invention, FIG. 2 is a sectional view of a damping force adjusting valve, FIG. 3 is a sectional view of another embodiment, and FIG. 4 is a characteristic of damping force. FIG. 1 damper, 2 damping force adjustment valve, 20 cylinder, 21 piston rod, 22 piston 23A, 23B
... oil chamber, 25 ... oil chamber, 30 ... passage, 36 ... bellows, 36A ... free piston, 38 ... pressure chamber, 40 ... valve spool, 41 ... plunger.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-95281 (JP, A) JP-A-59-146281 (JP, U) JP-A-60-45207 (JP, U) JP-A-59-146 192489 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) F16F 9/00-9/58 B62K 25/08 B60G 17/08 F16K 17/02

Claims (1)

(57) [Claims] When the damper is operated on the compression side or on the extension side,
In a damping force adjusting mechanism provided with a damping force adjusting valve for controlling opening and closing of a passage for releasing hydraulic oil from an oil chamber to an oil sump chamber by a control pressure according to a vehicle traveling state, the damping force adjusting valve has a passage closed. A bottom cylindrical spool guide, a through hole opened on the outer peripheral surface of the spool guide to allow hydraulic oil to escape to the oil reservoir, and a bottomed cylindrical valve spool fitted to the outer peripheral surface of the spool guide to open and close the through hole. , Penetrates the center of the spool guide bottom and abuts the inner bottom of the valve spool,
A plunger that senses the operating oil pressure in the oil chamber and presses the valve spool in the valve opening direction, a pressure chamber that exerts a control pressure on the valve spool against the plunger, and a partition that defines the pressure chamber as a passage for the operating oil. A damping force adjusting mechanism comprising: a member;