JPS63215463A - Power steering device - Google Patents

Abstract

PURPOSE:To properly suppress the increase of reaction force by interposing a unidirectional valve for cutting off the circulation of liquid to a reaction force hydraulic pressure chamber from a working liquid hydraulic pressure chamber into a bypass passage leading from the reaction hydraulic pressure chamber to the working hydraulic pressure chamber on each noncorrespondence side. CONSTITUTION:A pair of inner holes 21d and 21e are formed in the axial direction at the both edges of a valve spool 21, and reaction hydraulic chamber 28 and 29 are formed between a housing 11 and each inner hole 21d, 21e. The reaction hydraulic chambers 28 and 29 communicate to the respective annular grooves 21b and 21a through the orifices 30 and 31 formed on the valve spool 21, and one reaction hydraulic chamber 28 communicates to one working hydraulic pressure chamber 15 through passage 27. Further, the other reaction hydraulic pressure chamber 28 communicates to the other working hydraulic pressure chamber 16 through a bypass passage 32. In the bypass passages 32 and 33, unidirectional valves 34 and 35 for cutting off the liquid circulation from the working hydraulic pressure chamber to the reaction hydraulic pressure chamber are interposed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a power steering system for a vehicle, and more particularly to a reciprocating hydraulically actuated cylinder for moving a steering linkage mechanism of a vehicle. a hydraulic pump for delivering hydraulic fluid in a reservoir to the reciprocating hydraulic cylinder device, and a passage communicating with the hydraulic pump and a passage communicating with the reservoir of the reciprocating hydraulic cylinder. The input shaft includes a valve cylinder having a passage communicating with a re-operating hydraulic pressure chamber, and a valve spool that is slidably housed in the valve cylinder and slid back and forth by rotation of the input shaft. In response to the directional rotation, the hydraulic fluid from the hydraulic pump flows into one of the two working hydraulic chambers of the reciprocating hydraulic hydraulic cylinder, and the hydraulic fluid in the other hydraulic chamber flows. Hydraulic type in a power steering device comprising a control valve device that causes working fluid from the hydraulic pump to flow out into the reservoir and into the other working hydraulic chamber in response to rotation of the input shaft in the other direction. Regarding reaction force mechanism.

(Prior Art) Conventionally, there has been a device of this type as disclosed in Japanese Patent Publication No. 57-44502.

This device includes a valve cylinder having a passage communicating with a reservoir and a passage communicating with a re-operation hydraulic chamber of a hydraulic actuation cylinder, and a pair of annular grooves on the outer periphery of the valve cylinder so as to be slidable on the valve cylinder. a valve spool that is housed and slid back and forth by rotation of an input shaft; a pair of reaction pistons that are inserted into a pair of axial holes formed in the valve spool and are immovable relative to the valve cylinder; and an overpressure valve disposed in a reaction chamber defined by a reaction piston in the valve spool and communicating through a throttle hole with each annular groove of the valve spool. The inlet side of the overpressure valve is communicated with an inlet chamber formed by the casing and both ends of the valve spool, which are constantly connected to a hydraulic pump, and the outlet side thereof is communicated with each reaction chamber. Further, the annular groove of the valve spool, which communicates with each reaction chamber through the throttle hole, is alternately communicated with the passage communicating with the inflow chamber or the reservoir by movement of the valve spool, thereby creating a pressure difference between the chambers for both purposes, and A reaction force is applied to the valve spool due to the pressure difference.

Therefore, in conventional power steering devices, in order to reduce the large steering operation resistance that occurs during steering operations at relatively low travel speeds, for example when parking, an overpressure valve is installed when the reaction force exceeds a predetermined value. The valve is opened to inject pressure liquid from a hydraulic pump into the low-pressure side reaction chamber, or the high-pressure side reaction chamber is communicated with the reservoir.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional power steering device, due to the limitation of the installation space, the overpressure valve etc. are housed in the valve spool, resulting in a complicated structure. At the same time, internal leakage is likely to occur due to the gap between the overpressure valve and the valve spool, or the gap between the valve spool and the reaction piston (the gap required for assembly), and when internal leakage occurs, , there is a problem that an appropriate reaction force cannot be obtained.

Therefore, the technical object of the present invention is to prevent the steering operation reaction force from increasing at low speeds, etc., without complicating the structure or damaging the hydraulic reaction force mechanism.

[Structure of the invention]

(Means for Solving the Problems) The technical measures taken to solve the above-mentioned technical problems include a reciprocating hydraulic cylinder device for moving the steering linkage of a vehicle, A hydraulic pump for sending hydraulic fluid in a reservoir to a hydraulic cylinder device, a passage communicating with the hydraulic pump, a passage communicating with the reservoir, and a re-operating hydraulic pressure of the reciprocating hydraulic cylinder. The valve cylinder has a valve cylinder having a passage communicating with a chamber, and a valve spool that is slidably housed in the valve cylinder and is slid back and forth in response to rotation of the input shaft in one direction. to cause the hydraulic fluid from the hydraulic pump to flow into one of the re-operating hydraulic chambers of the reciprocating hydraulic hydraulic cylinder, and to cause the hydraulic fluid in the other hydraulic chamber to flow out into the reservoir; a control valve device that causes hydraulic fluid from the hydraulic pump to flow into the other hydraulic pressure chamber and hydraulic fluid from the one hydraulic pressure chamber to flow out to the reservoir in response to rotation of the input shaft in the other direction; In the power steering device, a pair of reaction force hydraulic pressure chambers are formed at both ends of the valve spool, and each of the pair of reaction force hydraulic pressure chambers is controlled to operate according to the rotation of the input shaft. The hydraulic pressure chambers are communicated through respective orifices, and the hydraulic pressure chamber on the non-corresponding side of the hydraulic pressure chamber is provided with hydraulic fluid from the reaction hydraulic pressure chamber provided in the power piston of the reciprocating hydraulic pressure cylinder. The communication is made through a one-way valve that allows liquid flow to the pressure chamber and blocks liquid flow from the working hydraulic pressure chamber to the reaction hydraulic pressure chamber.

(Function) As a result, a bypass passage is formed from the reaction force hydraulic pressure chamber to each of the non-corresponding working hydraulic pressure chambers via the one-way valve. As a result, the input shaft rotates in one direction, and the hydraulic fluid from the hydraulic pump flows into one hydraulic fluid chamber and flows into one reaction fluid chamber through the orifice, and the other hydraulic fluid chamber flows into the reservoir. At the same time, the other reaction hydraulic pressure chamber is communicated with the reservoir via the orifice, and when a pressure difference occurs between both reaction force hydraulic pressure chambers and a reaction force is generated, the hydraulic pressure in one reaction force hydraulic pressure chamber decreases. When the value exceeds a predetermined value, the one-way valve in the bypass passage opens, and the hydraulic fluid in one reaction hydraulic pressure chamber flows out through the bypass passage into the other hydraulic pressure chamber, appropriately suppressing the increase in reaction force. can do. In addition, since the one-way valve is installed inside the power piston of the reciprocating hydraulic cylinder device,
There is no need for a reaction piston and an overpressure valve as in the conventional device, thereby preventing the occurrence of internal leakage and preventing the function of the reaction force mechanism from being impaired.

(Example) Hereinafter, an example of a power steering device according to the present invention will be described based on the drawings.

1 to 3, the power steering device 10 includes a housing 11 fixed to a vehicle, an input shaft 12 rotatably disposed within the housing 11, and an input shaft 12 slidably and liquid-tightly disposed within the housing 11. a power piston 13 fitted with a
It has an output shaft 14 having a sector 14a that meshes with a recess 13a formed on the power piston 13.

The input shaft 12 is connected to a steering wheel (not shown), and the output shaft 14 is connected to a steering link mechanism (not shown).

The housing 11 and the power piston 13 have one working hydraulic pressure chamber 15 and the other working hydraulic pressure chamber 16 on both sides of the power piston 13.
A reciprocating hydraulically operated cylinder device is constructed.

In the power piston 13, hydraulic fluid from a hydraulic pump P (operated by the vehicle engine) flows into one of the re-operating hydraulic pressure chambers 15 and 16, and the other hydraulic fluid flows out into the reservoir R. Control valve device 17 for
A nut member 18 and a valve pin 19 for operating the control valve device 17 in accordance with the rotation of the input shaft 12 are arranged. The nut member 18 is connected to the input shaft 1
The input shaft 12 is threadedly engaged with the input shaft 12 via a ball 20 fitted between a threaded groove 12a formed on the outer periphery of the nut member 2 and a threaded groove 18a formed on the inner periphery of the nut member 18. 13, it is assembled so that it can rotate but cannot move in the axial direction. Therefore, when the input shaft 12 is rotated, the nut member 18 rotates together with the input shaft 12.

The valve pin 19 is fixed to the nut member 18, and its free end is inserted into the radial hole 21f of the valve spool 21 of the control valve device 17.

In FIGS. 2 and 3, the control valve device 117
has a valve spool 21 that is slidably housed in a valve cylinder 22 fitted into a lateral hole of the power piston 13 and is slid back and forth via a valve pin 19 by rotation of the input shaft 12. . Valve cylinder 22
A passage 23 that communicates with the hydraulic pump P, a passage 24 that communicates with the reservoir R that stores hydraulic fluid, and a re-operation hydraulic chamber 15.
It has passages 25, 26, and 27 communicating with ゜16,
The passages 23,24 open into annular grooves 22a, 22b formed in the inner bore of the valve cylinder 22. Further, the valve spool 21 has annular grooves 21 a, 2 l on its outer periphery.
b, 21 c, and a pair of inner holes 21 in the radial direction.
d, 21e. As a result, each working hydraulic pressure chamber 1
The passages 25° 26.27 communicating with 5.16 are opened to respective annular grooves 21c, 21a, and 21b, and there are throttles a, b, and c between the valve spool 21 and the valve cylinder 22.
, d are formed.

Further, a pair of inner holes 21d and 21e in the axial direction are formed at both ends of the valve spool 21, so that each inner hole 2
Reaction force hydraulic pressure chambers 2B are provided between 1d and 21e and the housing 11, respectively.
, 29 are formed. Each reaction pressure chamber 28,29 communicates with each annular groove 21b, 21a via an orifice 30.31 formed in the valve spool 21, so that one reaction force pressure chamber 28 is connected to one of the annular grooves 21b, 21a. It communicates with the working hydraulic pressure chamber 15 through a passage 27, and the other reaction force hydraulic pressure chamber 29 communicates with the other working hydraulic pressure chamber 16 through a passage 26. Further, one reaction force hydraulic pressure chamber 28 is communicated with the other working hydraulic pressure chamber 16 via a bypass passage 32 formed in the power piston 13, as shown in FIG. Similarly, the hydraulic pressure chamber 15 is connected to one of the hydraulic pressure chambers 15 via a bypass passage 33. A one-way valve 3 is provided in each of the bypass passages 32 and 33 to allow fluid flow from the reaction hydraulic pressure chamber to the working hydraulic pressure chamber and to block fluid flow from the working hydraulic pressure chamber to the reaction hydraulic pressure chamber.
4.35 is interposed.

The operation of this embodiment having the above configuration will be explained.

When the input shaft 12 is rotated clockwise in FIG. 2 showing the neutral position, the nut member 18 and the valve pin 19 are
The valve pin 19 moves the valve spool 21 inside the valve cylinder 22 to the right in FIG. 2.3. As a result, the restrictors a and c are further closed, and the restrictor d is opened again, and the working fluid from the hydraulic pump P passes through the path of passage 23 - annular groove 22b - restriction b - annular groove 21b - passage 27. It flows into the working hydraulic pressure chamber 15, and also flows into one of the reaction force hydraulic pressure chambers 28 from the annular groove 21b via the orifice 30. The hydraulic fluid in the other hydraulic pressure chamber 16 flows through the passage 26, the annular groove 21a, the throttle d, and the
It flows out to the reservoir R via the annular groove 22a-passage 24 path, and the other reaction force hydraulic pressure chamber 29 also communicates with the reservoir via the annular groove 21a-diaphragm d-annular groove 22a-passage 24 via the orifice 31. Ru.

This creates a pressure difference within the reactivation hydraulic pressure chambers 15 and 16,
The pressure difference causes the power piston 13 to tighten into the nut member 18.
The input shaft 12 is supported and moved in the advancing direction by screw engagement via the ball 20.

As a result, the output shaft 14 having the sector 14a meshing with the rack 13a of the power piston 13 is rotated, and the steering link mechanism connected thereto is operated, thereby reducing the steering force applied to the steering wheel. At the same time,
A pressure difference also occurs between the reaction force hydraulic chambers 28 and 29, and this pressure difference acts on the cross-sectional area of the outer diameter of the valve spool 21 in a direction that prevents movement by the valve pin 19, and this is transmitted to the driver as a reaction force. This prevents vehicle fluctuations when driving at high speeds.

Here, when steering at a relatively low speed, for example when parking, the steering reaction force due to the frictional force with the road surface, etc. In addition to the force, a large steering reaction force acts on the steering wheel. In such a state, when the pressure of the hydraulic fluid in one of the reaction force hydraulic pressure chambers 28 exceeds a certain value, the valve member 36 of the one-way valve 34 interposed in the bypass passage 32 is moved by the biasing force of the spring 37. The hydraulic fluid in one of the reaction force hydraulic pressure chambers 28 moves in the direction in which the bypass passage 32 opens against the flow, and the hydraulic fluid in one of the reaction force hydraulic pressure chambers 28 flows into the other hydraulic pressure chamber 16 that is communicated with the reservoir R via the bypass passage 32. It will be leaked. As a result, the pressure difference between both reaction force hydraulic pressure chambers 28 and 29 is reduced, and an increase in steering reaction force during parking or the like can be reduced.

The operation when the input shaft 12 is rotated clockwise in FIG.
The hydraulic fluid from is switched by the valve spool 21,
On the other hand, it flows into the working hydraulic pressure chamber 16 and the orifice 31.
The other reaction force flows into the hydraulic pressure chamber 29 via. Further, the working hydraulic pressure chamber 15 is communicated with the reservoir R, and the reaction hydraulic pressure chamber 28 is also communicated with the reservoir R through the orifice 30.

The resulting pressure difference within the re-actuation hydraulic pressure chambers 15 and 16 acts on the cross-sectional area of the power piston 13, causing the power piston 13 to move in the advancing direction through screw engagement via the nut member 18 and the ball 20 of the input shaft 12. Assist and move. As a result, the steering force applied to the steering wheel is reduced, and a pressure difference is created between the reaction pressure chambers 28 and 29, which pressure difference acts on the cross-sectional area of the outer diameter of the valve spool 21.

As a result, a force acts on the valve spool 21 in a direction opposite to the direction in which it is moved by the valve bin 19, and this force is transmitted to the driver as a reaction force. When the pressure in the other reaction force hydraulic pressure chamber 29 that provides this reaction force exceeds a predetermined value, the one-way valve 3
When the valve 5 is opened, the bypass passage 33 is opened, and the hydraulic fluid in the reaction hydraulic pressure chamber 29 flows out from the bypass passage 33 into the hydraulic pressure chamber 15 communicating with the reservoir R. As a result, the pressure difference between the reaction force hydraulic chambers 28 and 29 is reduced, and an increase in the steering reaction force can be appropriately suppressed.

Although one embodiment of the present invention has been described above, the cylinder device, the control valve device, and the connection structure between the input shaft and the control valve device of the present invention are not limited to the structure of the one embodiment. It can be changed as appropriate within the range described in the range.

〔Effect of the invention〕

As described in detail above, according to the present invention, complicated machined parts are not required within the control valve device, particularly within the valve spool, and the control valve device can be manufactured at low cost.

In addition, since the pressure difference between the two reaction force hydraulic pressure chambers acts on the cross-sectional area of the outer diameter of the valve spool, it is possible to obtain a large reaction force, and since the entire area of the valve spool is used as damping volume, the valve The vibration damping effect of the spool is extremely high, which greatly improves the steering feel.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the power steering device according to the present invention, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. Operation diagram, 4th
The figure is a sectional view taken along line BB in FIG. 10... Power steering device, 11... Housing, 12
...Input shaft, 13...Power piston, 14...
Output shaft, 15... One working hydraulic pressure chamber, 16... Other working hydraulic pressure chamber, 17... Control valve device, 18.
...Nut member, 19...Valve piston, 21...
・Valve spool, 22...Valve cylinder, 28・
...One side reaction force hydraulic pressure chamber, 29...The other side reaction force hydraulic pressure chamber, 30
゜31...Orifice, 34.3'5...One-way valve.

Claims (1)

[Claims] A reciprocating hydraulic cylinder device for moving a steering linkage mechanism of a vehicle, a hydraulic pump for sending hydraulic fluid in a reservoir to actuate the reciprocating hydraulic cylinder, and a passage communicating with the hydraulic pump. a valve cylinder having a passage communicating with the reservoir and a passage communicating with both working hydraulic pressure chambers of the reciprocating hydraulic actuating cylinder; and a valve spool that is slidable in a reciprocating manner, so that in response to unidirectional rotation of the input shaft, one of the two working hydraulic chambers of the reciprocating hydraulic actuating cylinder receives actuation from the hydraulic pump. The hydraulic fluid is caused to flow into the other hydraulic pressure chamber, and the hydraulic fluid from the other hydraulic pressure chamber is caused to flow out into the reservoir, and the hydraulic fluid from the hydraulic pump is caused to flow into the other hydraulic pressure chamber in response to rotation of the input shaft in the other direction. In the power steering device, the power steering device is provided with a control valve device for causing the hydraulic fluid in the one hydraulic pressure chamber to flow out to the reservoir, wherein a pair of reaction hydraulic pressure chambers are formed at both ends of the valve spool, and the pair of reaction force The hydraulic pressure chambers are respectively communicated with the corresponding working hydraulic pressure chambers via respective orifices in accordance with the rotation of the input shaft, and the reciprocating pressure chambers are communicated with the working hydraulic pressure chambers on the non-corresponding side of the working hydraulic pressure chambers. A one-way valve installed in the power piston of a dynamic hydraulic cylinder device that allows liquid flow from the reaction hydraulic pressure chamber to the working hydraulic pressure chamber, and blocks liquid circulation from the working hydraulic pressure chamber to the reaction hydraulic pressure chamber. Power steering device communicated via a valve.