JPS6243367A - Steering damper - Google Patents

Abstract

PURPOSE:To provide a steering damper for power steering which enables improvement of maneuvering stability, by a method wherein a check valve and a variable throttle valve are mounted to a circuit through which an oil chamber in a steering damper body is communicated with a servo valve. CONSTITUTION:A steering damper body 10 is formed such that oil chambers 14 and 15 are partitioned in a housing 11 by means of a piston 13 secured on a rack shaft 12, an oil is fed and discharged from and to the outside through oil passages L1 and L2. A servo valve 20 switched through control of a handle feeds pressure oil to either an oil passages L1 or L2. A damper part 30 is dis posed in the oil passages L1 and L2, a check valve 31a and a varying throttle valve 32a are located in the oil passage L1, and a check valve 31b and a varying throttle valve 32b are situated in the oil passage L. The varying throttle valves 32a and 32b vary in their openings depending upon vibration frequency in the oil chambers 14 and 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a steering damper, and particularly to an improvement of a steering damper for power steering.

[Conventional technology]

Steering dampers that have been conventionally provided include, for example, a shock absorber type shown in FIG. 3 and a valve type steering damper shown in FIG. 4 for manual operation.

That is, the shock absorber type steering damper shown in Fig. 3 has a damping section 2 integrally attached to a steering damper body 1, and is connected to the axle side with respect to the housing 1a that is connected to the vehicle body side. When moving the rack shaft 1h.

The damping section 2 is intended to exert a predetermined damping action, and the piston rod 2a of the damping section 2 is connected to the housing 1α side, and the cylinder 26 is connected to the rack shaft 1h.
The purpose is to generate a predetermined damping force when the piston rod 2α moves in and out of the cylinder 2h.

Therefore, there is no problem in itself when the above-mentioned shock absorber type steering damper is installed in a vehicle as a steering damper for power steering using hydraulic pressure.

However, with power steering, the return of the steering wheel is more likely to be difficult than with the above-mentioned steering damper for manual operation, and if the above-mentioned shock absorber type steering damper is installed, the return of the steering wheel is even more difficult.

Therefore, the damping force in the steering damper can be adjusted, and the damping force is increased in the normal steering angle range during high speed driving where shimmy is likely to occur, and the damping force is increased in the steering angle range during low speed driving where there is no fear of shimmy occurring. However, in the above-mentioned shock absorber type, adjusting the damping part 2 so that the same damping force is generated in the left and right directions in the figure means that the area to which high pressure is applied in the left and right directions is different depending on the piston rod 2a. , there are extremely difficult problems.

On the other hand, the valve-type steering damper shown in FIG.
The oil from the oil chambers 3d and 3e defined by the piston 3C fixed to the valve unit 4 is transferred to the oil chambers 4α and 4 of the valve unit 4.
b and passing through valves 4c, 4d,
This is to generate a predetermined damping force.

Therefore, according to the conventional example shown in FIG. 4, the damping force adjustment in the left and right direction described above can be adjusted as desired.

[Problem that the invention seeks to solve]

However, in the proposal shown in Fig. 4, that is, when a valve-type steering damper is used as a steering damper for power steering, the inside of the housing 3α is used as a so-called pressure chamber, so the above-mentioned There is an inconvenience in that it is difficult to use a valve-type steering damper as it is for power steering.

In other words, the various things that have been proposed in the past are not suitable as steering dampers for power steering;
Therefore, it is currently desired to propose a steering damper itself for power steering.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, an object of the present invention is to provide a new optimal steering damper for power steering.

[Means for solving problems]

In order to solve the above-mentioned problems, the configuration of the present invention includes a check valve and a variable throttle valve in a circuit that allows communication between the oil chamber in the steering damper body and an external servo valve. With.

The variable throttle valve is characterized in that the opening degree thereof is made variable depending on the vibration frequency within the oil chamber.

〔Example〕

The present invention will be explained below based on the illustrated embodiments.

As shown in FIG. 1, the steering damper according to the present invention includes a steering damper main body 10 and a servo valve 20.
and a damper section 30.

The steering damper main body 10 has a rack shaft 12 in a housing 11 so as to be movable in the left-right direction in the figure, and a piston 13 fixed to the rack shaft 12 forms an oil chamber in the housing 11. Sections 14 and 15 are formed. Oil is supplied to the oil chambers 14 and 15 from the outside via oil passages L/ and LJ, and
It is designed to be ejected.

The steering damper body 10 is used as a cylinder for power steering, and the rack shaft 12
Both ends of the housing 11 are connected to the axle side of the vehicle, and the housing 11 is connected to the body side of the vehicle.

The servo valve 20 is connected to the oil passages Ll and La that allow oil to be supplied to the oil chambers 14 and 15, and directs pressure oil from the external pump P to either one of the oil passages Ll and La. It is formed to supply pressurized oil and to return the return oil from either one of L/ and Lλ to the reservoir tank T.

In this embodiment, the servo valve 20 is configured to be switched by operating the steering wheel of the vehicle.

The damper section 30 includes the steering damper main body 10
Oil passages L/, L are circuits connecting the servo valve 20 and the
λ, the oil passage Ll has a check valve 311m and a variable throttle valve 32α,
In the oil passage Lλ, a check valve 316 and a variable throttle valve 3 are provided.
2A. And each check valve 31α, 3
1h is formed to allow oil from the former servo valve 20 to pass toward the oil chambers 14, 15 of the steering damper main body 10, but not to allow the oil to flow backwards, and each variable throttle valve 32α, 326 is , is formed to allow oil to pass from the oil chambers 14, 15 toward the servo valve 20, and to generate a predetermined damping force when the oil passes.

Note that in the damper section 30, the variable throttle valve 3212
, 32h are arranged in series with each other.
a, 33b, but the check valve 33α,
336 may be omitted.

Each variable throttle valve 32a in the damper section 30.

In the present invention, 32b is formed so that its opening degree is variable depending on the vibration frequency in the oil chambers 14 and 15 of the power steering damper 10, and in particular, when the vibration frequency is constant. When the damping force is within the above-mentioned range, a low damping force is generated, but when the above-described certain range is exceeded, a high damping force is generated. That is, it is formed as a so-called low-cut valve that depends on the vibration frequency.

Figure 2 shows an embodiment of the variable throttle valve 32α (327!I), and in this embodiment, the check valve 3 parallel to the variable throttle valve 32α (321!L) is shown in FIG.
1a (31, 6) is also included.

That is, the block 4 is located in the center of the valve housing 40.
The block 41 defines an upper oil chamber A and a lower oil chamber B within the valve housing 40. The upper oil chamber A and the lower oil chamber B communicate with each other through a port 40α drilled in the thick outer circumferential portion of the valve housing 40, and the upper end opening of the port 40α, that is, On the upper oil chamber A side, there is a leaf valve 4 as the check valve 31α (3LA).
2 are placed adjacent to each other. Note that the leaf valve 42
An initial load is applied to the non-return spring 42b whose upper end is locked to the stopper 42α.

A port 41α is bored in the outer peripheral thick portion of the block 41 to enable communication between the upper oil chamber A side and the lower oil chamber B side. And the above port 4
A leaf valve 43 as a variable throttle valve 32α (32b) is arranged adjacent to the lower end opening of 1α.

The leaf valve 43 is supported at a support point 44α of the disk 44 from below so that the outer peripheral end is free, and
A pressing point 45α of the bushing valve 45 from above is in contact. That is, the disk 44 is fitted inside the lower center of the valve housing 40, and the support point 44α is positioned near the inner peripheral end of the leaf valve 43. Further, the bushing valve 45 is housed inside the center of the block 41 so as to be able to move up and down, and the position of the pressing point 45α is on the outer circumferential side of the leaf valve 41 from the position of the supporting point 44a. ing.

Therefore, when the oil from the upper oil chamber A side flows out to the lower oil chamber B side through the port 41α of the block 41, the leaf valve 43 generates a desired damping force by bending its outer peripheral end. When the bushing valve 45 is lowered by an external force from above, the amount of deflection of the outer peripheral end of the leaf valve 43 is increased, and the damping force is suppressed to a low level. Become.

Above the bushing valve 45 in the block 41,
A coil spring 46 is housed, and a spool 47 that is in contact with the upper end of the coil spring 46 is housed. A decompression chamber 41A is formed between the thick portion of the block 41 and the spool 47.

That is, the decompression chamber 41b is formed by an orifice 48 of a check valve 48 disposed so as to close the upper part of the spool 47.
It communicates with the upper oil chamber A via α.

In addition, the check valve 48 is connected to the conical spring 4
The conical spring 48A is energized from above to below by the stopper 42a. Furthermore, the stopper 42a has a through hole 42α formed in its center, and an upper oil chamber A.
The check valve 48 side is connected to the check valve 48 side. Furthermore, the disk 44 has through holes 44h, 44.
Through holes 40h and 40C are formed in the upper and lower thick parts of the valve housing 40, respectively, to allow communication between the front side and the rear side of the disc 44.
The steering damper main body 10 and the servo valve 20 can communicate with the inside of the valve housing 40 via the oil passage L.

The operation of the steering according to the present invention configured as above will be briefly explained.

First, in Figure 1, when the handle is operated so that the rack shaft 12 of the steering damper body 10 is moved, for example, to the right in the figure, pressure oil from the servo valve 20 flows through the oil path L/, The oil flows into the oil chamber 14 through the check valve 31α, pushing the piston 13 to the right in the figure, thereby facilitating the above-mentioned handle operation.

At this time, the oil from the other oil chamber 15 is removed from the check valve 3.
1h, the flow is blocked and flows into the servo valve 20 via the variable throttle valve 32A, and a desired damping effect is exerted when passing through the variable throttle valve 32II. The opening degree at which oil passes through the variable throttle valve 32A is changed depending on the vibration frequency within the steering damper body 10.

That is, in Figure 2, when oil is about to pass from the steering damper body 10 side to the servo valve 20 side, the vibration frequency in the steering damper body 10 becomes the vibration frequency in the upper oil chamber A, and therefore, When the vibration frequency is within a predetermined range, high pressure is generated in the decompression chamber 41A, and the spool 47 is lowered against the repulsive force of the coil spring 46, causing the bushing valve 45 to move downward. A downward external force will be applied, and this external force will be applied closer to the inner peripheral end of the leaf valve 43.

As a result, the outer peripheral end of the leaf valve 43
As a result, the damping force can be suppressed to a low level.

When the vibration frequency exceeds a certain range, high pressure will no longer be generated within the decompression chamber 41.6, and therefore the spool 47 will no longer descend within the block 41, causing the leaf valve 43 The pressing force applied to the inner circumferential end of the leaf valve 43 is released, and the leaf valve 43 is returned to its initial deflection characteristics, and a high damping force is generated from then on.

That is, the variable throttle valve 3 constituted by the leaf valve 43
The opening degree of the variable throttle valve 32α (32A) is variable depending on the vibration frequency, and in order to make the opening degree of the variable throttle valve 32α (32b) variable, detection means such as other sensors,
Control means such as actuators for opening and closing the flow path are not required.

As a result, when the running speed of the vehicle is low and the vibration frequency is low, the variable throttle valve 32a (32A) is in the open direction, allowing smooth passage of oil and facilitating steering operation. , when the traveling speed of the vehicle is high and the vibration frequency is in a large range, the variable throttle valve 32a
(32A) is in the closing direction, which obstructs the passage of oil, ensures stability in steering wheel operation, and helps prevent shimmy.

〔Effect of the invention〕

As described above, according to the present invention, since the opening degree of the variable throttle valve is made variable depending on the vibration frequency when the vehicle is running, friction can be reduced when the vehicle is running at low speed.
The present invention provides a steering damper for power steering that improves the return performance of the steering wheel, prevents shimmy during high-speed driving, and improves steering stability.

According to the present invention, unlike the conventional example in which a damping section is attached integrally to the steering damper main body, when the rack shaft in the steering damper main body is moved, only the friction generated in the main body portion is sufficient. This has the advantage that its operating performance is improved.

Further, according to the present invention, unlike the conventional example in which a damping section is integrally attached to the steering damper body via a bracket serving as a strength member, there is no need for a strength member.
This has the advantage of reducing the number of parts and making it easier to obtain reliability.

Furthermore, according to the present invention, it is sufficient to dispose the damper part in the oil path between the servo valve and the steering damper body, so there is an advantage that there are no restrictions on the mounting position when installing it in a vehicle. There is.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the principle of the structure of the steering damper according to the present invention, Fig. 2 is a sectional view showing an embodiment of the damper part in the present invention, and Figs. 3 and 4 are views of a conventional steering damper. FIG. 2 is a partially cutaway front view. DESCRIPTION OF SYMBOLS 10... Steering damper main body, 11... Housing, 121-Rack shaft, 13... Piston, 14.
15...Oil chamber, 20...Servo valve, 30・e-
Damper part, 31a, 31A ---Check valve, 32
α, 32h...Variable throttle valve, 40...Valve housing, 41...Block, 41A--Decompression chamber, 43
---Leaf valve, 44- ・Disk, 44α・・
・Support point, 45... push hartz, 45αass
Pressure point, 46... Coil spring, 47... Spool, 48... Check valve, 48a... Orifice, L/, Lλ... Oil path, P... Pump, T... Reservoir tank. Figure 3

Claims (2)

[Claims] (1) In a steering damper comprising a steering damper body and a servo valve connected to an oil chamber in the steering damper body, a check valve and a variable throttle are included in the circuit communicating the oil chamber and the servo valve. What is claimed is: 1. A steering damper comprising: a variable throttle valve; the variable throttle valve is formed to vary its opening degree depending on the vibration frequency within an oil chamber; (2) A patent claim in which the variable throttle valve has a large opening until the vibration frequency in the oil chamber reaches a certain range, and a small opening when it exceeds the above-mentioned certain range. The steering damper according to the range 1 above.