JPH0249109Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a steering damper, in particular,
This article relates to improvements to steering dampers for power steering.

[Conventional technology]

As a steering damper for power steering, there is a shock absorber type steering damper shown in FIG. 4, for example.

That is, this conventional shock absorber type steering damper has a damping section 2 attached to a steering damper body 1, and a rack shaft 1b connected to the axle side is connected to a housing 1a connected to the vehicle body side. When moving, the damping section 2 is intended to exert a predetermined damping effect,
The piston rod 2a of the damping section 2 is connected to the housing 1a side, and the cylinder 2b is connected to the rack shaft 1b.
When the cylinder a moves in and out of the cylinder 2b, a predetermined damping force is generated by the fixed throttle 2d of the piston portion 2c to buffer the damping force.

On the other hand, the inside of the housing 1a is partitioned by a piston part 1c fixed to a rack shaft 1b.
Oil chambers 1d and 1e are formed, and each oil chamber 1
d and 1e communicate with the external switching valve 3 via oil passages L ₁ and L ₂ , respectively, and a handle (not shown).
By this operation, pressure oil is supplied to either one of the oil chambers 1d or 1e, and oil is returned from the other oil chamber 1e or 1d.

Therefore, by supplying pressure oil to the oil chambers 1d and 1e in the housing 1a of the steering damper body 1, the rack shaft 1b can be moved, and the desired direction of the vehicle can be controlled, and the rack shaft 1b can be moved. The damping portion 2 can prevent shimmy from the outside, particularly from the wheels.

[Problem that the invention attempts to solve]

However, in the above proposal, the damping section 2
Although a damping effect against external forces can be expected, there is a disadvantage that the return operation of the steering damper body 1, that is, the return performance of the steering wheel, is impaired by the friction of the seal etc. of the damping part 2.

In addition, when attaching the damping part 2 to the steering damper body 1, the bracket parts 1f and 1g are
It is necessary to use the damping section 2 as a strength member, which is disadvantageous in that it is heavy and the structure of the damping section 2 is complicated, which also increases the cost.

Furthermore, the fixed aperture 2d of the damping section 2 is connected to the rack shaft 1.
The fixed orifice 2d effectively damps the relatively large external force applied to the shaft 1b, but when the rack shaft 1b vibrates with a small amplitude in the left-right direction due to an input caused by tire imbalance, the fixed throttle 2d It is not possible to completely eliminate the so-called shimmy phenomenon, where the flow cannot be throttled down and the handle oscillates slightly.

Furthermore, in order to obtain a damping effect using the fixed orifice 2d, the fixed orifice diameter is made small, but in this case, for example, when the steering wheel is operated quickly to avoid an obstacle when driving at high speed, the flow rate passing through the fixed orifice 2d increases at the steering speed. The generated pressure also increases in proportion to. For this reason, this generated pressure acts as resistance, resulting in a loss of hydraulic thrust of the rack shaft 1b, causing the steering wheel steering force to suddenly increase, making the driver feel strange when operating the steering wheel.

[Purpose of invention]

Therefore, the purpose of the present invention is to maintain the return performance of the handle, eliminate the need for a damping section with a strength member, simplify the structure, reduce weight, prevent the shimmy phenomenon, and at the same time To provide a steering damper that does not give a strange feeling to operation.

[Means for solving problems]

In order to achieve the above object, the present invention provides a steering damper for power steering comprising a steering damper body and a switching valve connected to the oil chamber in the steering damper body. The circuit connecting the valve has a check valve that allows oil to flow only from the switching valve side to the oil chamber side, and a throttle check valve that has an initial load and allows oil to flow only from the oil chamber side to the switching valve side. It is characterized by being provided with a valve.

〔Example〕

Hereinafter, the present invention will be explained 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 switching valve 20. As shown in FIG.

The steering damper main body 10 has a rack shaft 12 in a housing 11 so as to be movable in the left and right directions in the figure.
housing 1 by a piston 13 fixed to
Hydraulic pressures 14 and 15 are divided into sections. The oil chambers 14 and 15 are connected to oil passages L _{1 and 15} from the outside.
Pressure oil is supplied through _L2 , and the oil returns to the outside from each oil chamber 14, 15 and is discharged.

The steering damper main body 10 is used as a cylinder for power steering, and both ends of the rack shaft 12 are connected to the axle side of the vehicle, and the housing 11 has mounting parts 10a, 1
It is connected to the vehicle body side of the vehicle via 0b.

The switching valve 20 is connected to each of the oil chambers 14 and 15.
It is connected to the ends of the oil passages L ₁ and L ₂ connected to the oil passages L 1 and L 2 , and the pressure oil from the pump (not shown) is switched by the switching valve 20 to the oil passages L 1 and L ₂ .
The oil is discharged to either one of _L2 , and the return oil from the other is formed to flow into a tank (not shown).

In this embodiment, the switching valve 20 is configured to be switched by rotating the operating rod 16 that allows the steering wheel of the vehicle to be operated.

In the oil passages L ₁ and L ₂ which are circuits connecting the steering damper main body 10 and the switching valve 20,
A check valve 17 and a throttle check valve 18 are provided.

That is, in this embodiment, the oil passage L ₁ ,
It is assumed that the check valve 17 and the throttle check valve 18 are housed in a connector bolt 19 disposed at a connecting portion with the steering damper main body 10 at the tip of _L2 .

The connector bolt 19 includes a casing 19a fixed to the outer peripheral surface of the housing 11 of the steering damper main body 10, a cap 19b screwed onto the casing 19a, and a cap 19b.
and a mounting member 19c that is interposed between the casing 19a and the casing 19a when the mounting member 19c is screwed onto the casing 19a. and,
The check valve 17 and the throttle check valve 18 are housed in the oil chamber 19a' inside the casing 19a. At the same time, the oil chamber 19a' in the casing 19 and the mounting member 1 are connected via the port 19b' in the cap 19b.
9c is allowed to communicate with the through hole 19c'. Note that a pipe 21 constituting oil passages L ₁ and L ₂ communicating with the switching valve 20 is connected to the mounting member 19c, and a port opposite to the port 11a of the housing 11 is provided at the lower end of the casing 19a. 19a'' is drilled.

The check valve 17 has a steel ball 17a.
The throttle check valve 18 includes a valve element 18a that faces and abuts the steel ball 17a, and a spring 17b that urges the valve element upwardly, that is, toward the cap 19b. It consists of a spring 18b that biases downward, that is, toward the inner bottom of the casing 19a. The valve body 18a allows its central port 18a' to be closed by the steel ball 17a, and its lower end surface is brought into close contact with the inner bottom upper surface of the casing 19a by the biasing force of the spring 18b. .

Note that the spring 1 that biases the valve body 18a
The biasing force of the spring 8b is of course greater than the biasing force of the spring 17b that biases the steel ball 17a, and biases the valve body 18a with a preset initial load. Further, the biasing force of the spring 17b that biases the steel ball 17a is set to such a level that the steel ball 17a does not separate from the valve body 18a, which is a valve seat, due to vibration or its own weight.

The principle of the present invention described above is shown in FIG. 3.

That is, in FIG. 3, when the steering wheel is operated so that the rack shaft 12 of the steering damper body 10 is moved to the right in the figure,
Pressure oil from the pump P passes through the oil passage _L1 through the switching valve 20, which is switched by the rotation of the operating rod 16 (see Fig. 1), and enters the oil chamber 14 through the check valve 17. The piston 13 is pushed toward the right in the figure, thereby facilitating the above-mentioned handle operation.

At this time, from inside the other oil chamber 15, the oil whose flow has been blocked by the check valve 17' flows into the oil passage _L2 through the throttle check valve 18', and then flows through the switching valve 20 into the tank. Flows into T. When oil passes through the throttle check valve 18', the spring 18b with the initial load set is sufficiently compressed, so that the passage of oil is not obstructed and the operating feel of the handle is not impaired.

Furthermore, when the rack shaft ₁₂ moves to the left in FIG. returns to the switching valve 20 via the throttle check valve 18 and via the oil path _L1 . At that time, the throttle check valve 18 is sufficiently opened without obstructing the passage of oil.

When the rack shaft 12 oscillates slightly in the left and right directions in FIG. This contributes to preventing shimmy.

In the present invention, as described above, the oil passage serving as a circuit is
The reason for disposing the check valve 17 and the throttle check valve 18, which are damping parts, in _L1 and _L2 is, for example, because the check valve 17 and the throttle check valve 18
If a fixed throttle is installed instead, there is a risk that the damping force will become too large for high input speeds, impairing the feel of the steering wheel. This is done in consideration of the inconvenience that since pressure oil is supplied to the oil chambers 14 and 15, the suction of oil in each oil chamber 14 and 15 becomes poor and the vacuum phenomenon is likely to occur.
This is in consideration of the fact that even if the vacuum phenomenon is prevented by disposing a check valve in parallel with the fixed throttle, there remains a risk that the operational feeling of the steering wheel will be impaired.

Therefore, in the present invention, a check valve 17 and a throttle check valve 18, which constitute a damping section, are provided in the circuit connecting the steering damper main body 10 and the switching valve 20.

[Effect of idea]

According to the present invention, there are the following effects.

Since a check valve and a throttle check valve are provided in the circuit connecting the oil chamber and the switching valve, there is no need for a conventional damping section and a strong bracket to attach it, resulting in a simple structure and light weight. can. Furthermore, since no friction problem occurs, the return operation of the steering damper body, that is, the return performance of the steering wheel, is not impaired.

Since the throttle check valve has an initial load, oil from the oil chamber will flow to the switching valve side even if the easy shaft of the steering damper body experiences minute vibrations due to unbalanced tires, etc. This prevents the rack shaft from moving, thereby preventing the so-called shimmy phenomenon in which the handle moves slightly.

The throttle check valve opens against the set initial load when the handle is operated quickly, and its opening area ensures a sufficient flow path compared to conventional fixed throttles, and there is no loss of hydraulic thrust from the rack shaft. Does not cause discomfort when operating the steering wheel.

[Brief explanation of the drawing]

Fig. 1 is a partially cut-away front view showing a steering damper according to an optimal embodiment of the present invention, Fig. 2 is a sectional view showing an enlarged damping section, and Fig. 3 is a section according to the present invention. FIG. 4, which is a diagram illustrating the principle, is a partially cutaway sectional front view showing a conventional steering damper. 10... Steering damper body, 11... Housing, 12... Rack shaft, 13... Piston, 14, 15... Oil chamber, 17... Check valve,
18...throttle check valve, 20...switching valve valve, _L1 , _L2 ...oil line.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A steering damper for power steering comprising a steering damper body and a switching valve connected to an oil chamber in the steering damper body, wherein the oil chamber and the switching valve are connected to each other. In the circuit connecting the , there is a check valve that allows oil to flow only from the switching valve side to the oil chamber side, and a throttle check valve that has an initial load and allows oil to flow only from the oil chamber side to the switching valve side. A steering damper characterized by being arranged. (2) The steering damper according to claim 1, wherein the check valve and the throttle check valve are housed in a connector bolt fixed to the outer peripheral surface of the cylinder of the steering damper body.