JPH06278623A - Servo valve - Google Patents

Abstract

PURPOSE:To prevent the variance in the characteristics and abnormal noise by providing a pressure controlling land part and a pressure characteristic adjusting land part where the chamfering for throttle control is formed on a fitting part of a sleeve valve member and a rotor valve member in a servo valve for the power steering device of an automobile. CONSTITUTION:Eight (8) recessed grooves 42 are formed on the inner circumference of a sleeve valve member 40, and a land part 41 is formed between the respective recessed grooves 42. A land part 31 is formed on the outer circumference of the rotor valve member 30 by making correspondence with the recessed groove 42 of the sleeve valve member 40. Recessed grooves 32 are formed between the respective land parts 31. Supply holes 43 are opened for every other land parts 41, and connected to a supply pump 50. The land part 31 opposite to the recessed groove 32 between the supply hole 31 and the discharge hole 33 is made the control land part 411, while the other land parts are made the adjustment land part 412, and the first chamfering N which is gradually inclined to the control land part 411 and the second chambering U which is steeply inclined from the adjustment land part 412 are formed respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo valve used in a power steering system for an automobile.

[0002]

2. Description of the Related Art A rotary type servo valve used for a power steering apparatus of an automobile has a characteristic that, as shown in FIG.
There is a region where the hydraulic assist does not work while is small, and when the steering wheel torque exceeds a certain value p, the steering assist increases gently, and further, when the steering torque exceeds q, the steering assist increases rapidly. The required two-step folding characteristic is required.

In order to obtain such pressure characteristics, there is a technique disclosed in, for example, Japanese Patent Laid-Open No. 63-215462. As shown in FIGS. 13 and 14, this is a control land of the sleeve valve member 40 that underlaps with the land portion 31 of the rotor valve member 30 in the fitting position of the rotor valve member 30 and the sleeve valve member 40 in the neutral position. A pressure control land portion Z1 having a pressure control land portion Z1 and a pressure characteristic adjustment land portion Z2 having an adjustment land 412 of the sleeve valve member 40 overlapping the land portion 31 in the neutral position.
It is a configuration in which is arranged.

As shown in FIG. 14A, the land portion 31 of the pressure controlling land portion Z1 is in communication with the discharge chamber 33 and the supply chamber with which the supply hole 43 communicates with the relative rotation of both valve members. A first chamfer 36 that controls the throttle so as to gradually reduce the communication area with the discharge chamber is formed, and the land portion 31 of the pressure characteristic adjusting land portion Z2 has one end surface on which one end surface is formed.
As shown in FIG. 4 (B), a second chamfer 37 that controls the throttle so that the communication area between the supply chamber and the discharge chamber is gradually increased with the relative rotation of both valve members is provided on the other end face.
As shown in (C), the third chamfer 38 is formed to control the throttle so as to gradually reduce the communication area between the supply chamber and the discharge chamber. By these three types of chamfering operations, the supply holes 44 and 45 are controlled so as to have a two-step folding assist characteristic in accordance with the handle torque TM (rotation angle).

[0005]

In the above configuration,
The three types of chamfered shapes produce characteristics by combining the throttling action, but it is difficult to form these three types of chamfered shapes, and variations in the characteristics and abnormal noise (shoe noise of the fluid diaphragm) occur significantly. There is a problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and comprises a supply hole for supplying a pressure fluid and a controlled element for supplying the pressure fluid supplied from the supply hole. And a discharge valve for discharging the pressure fluid, the sleeve valve member and the rotor valve member are fitted to each other so that they can rotate relative to each other. A pressure control land portion provided on the valve member with a control land for controlling the supply and discharge of the pressure fluid from the supply hole to the distribution hole between the valve member and the land portion of the other valve member; Plural supply to the fitting portion, by alternately arranging with a land portion of the valve member, a pressure characteristic adjusting land portion provided with an adjusting land for controlling the pressure fluid from the supply hole to the discharge hole. Located between the chamber and the discharge chamber A plurality of control chambers are formed, and a first chamfer is formed in the pressure control land portion so as to reduce the communication area between the supply chamber and the control chamber gradually as the valve members relatively rotate. Then, a second chamfer is formed on the pressure characteristic adjusting land so as to gradually increase the communication area between the supply chamber and the discharge chamber with the relative rotation of the valve members, and the second chamfer is formed. A fixed throttle is provided in the discharge hole on the downstream side of the chamfer or the supply hole on the upstream side.

[0007]

With the above structure, the throttle area with respect to the rotation angle of the valve is a combined area of the first chamfer and the second chamfer with the fixed throttle, and as a result, the flow rate increases linearly.
Prevents an increase in flow rate per throttle passage.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. A power steering apparatus in which the servo valve of the present invention is adopted will be described with reference to FIGS. 1 and 2. The output shaft 12 is rotatably supported in the gear housing 10 and the valve housing 11 fixed to each other via bearings 18 and 18a.
The pinion 12a of the output shaft 12 has a rack tooth 15 of a rack shaft 15 slidably supported in a direction intersecting with the pinion 12a.
It meshes with a. Power cylinder 1 for rack shaft 15
The piston 17 of No. 6 is fixed, and the steering wheel is connected via a link mechanism (not shown).

An input shaft 13 connected to a steering handle via a handle shaft is provided in each of the housings 10 and 11.
It is supported coaxially with the output shaft 12 via bearings 19 and 19a, and these shafts 12 and 13 are elastically relatively rotatably connected by a torsion bar 14. Both axes 1
A rotary servo valve 20 according to the present invention is provided between 2 and 13. The rotary servo valve 20 includes a rotor valve member 30 formed on the input shaft 13,
The sleeve valve member 40 is rotatably fitted to the outer circumferential surface and the inner circumferential surface 11a of the valve housing 11 and is coupled to the output shaft 12 by a coupling pin 25. The sleeve valve member 40 includes a supply port 51, a discharge port 52, and a pair of supply and discharge ports. A rotary 4-port throttle switching valve having ports 53 and 54 is formed.

That is, as shown in FIG. 2, eight concave grooves 42 are formed on the inner circumference of the sleeve valve member 40, and a land portion 41 is formed between these concave grooves 42. Further, eight land portions 31 corresponding to the concave grooves 42 of the sleeve valve member 40 are formed on the outer periphery of the rotor valve member 30, and concave grooves 32 are formed between these land portions 31.
The sleeve valve member 40 has a land portion 41 in which alternate supply holes 43 are formed.
To a supply port 51 to which the pressure fluid from is supplied. Then, as shown in FIG. 3, among the concave grooves 32 of the rotor valve member 30, those communicating with the supply hole 43 are the supply chamber R.
0 and R6 are formed, and the others form discharge chambers R3 and R4. As shown in FIGS. 1 and 2, the discharge chambers R3 and R4 are provided with discharge holes 33 and 33A, respectively, and these discharge holes 33 and 33A are provided in the passage 55 between the input shaft 13 and the torsion bar 14 and the input shaft 13, respectively. It is connected to a discharge port 52 which communicates with a reservoir 57 via a through hole 56 provided in the.

The land portion 31 (hereinafter, referred to as a control land portion 411) formed so as to face the concave groove 42 located between the supply hole 43 and the discharge hole 33, and other than the control land portion 411. The land portions 31 (hereinafter, referred to as adjustment land portions 412) are located between the land portions 41 of the sleeve valve member 40 in the neutral state in the drawing so that they do not overlap each other.

Between the two valve members 30 and 40 as described above,
As shown in FIG. 3, in the neutral state, the control land portion 41
1 and the land portions 41 facing each other on both sides constitute a pressure control land portion Z1, and the adjusting land portion 412 and the land portions 41 facing each other on both sides configure a pressure characteristic adjusting land portion Z2. There is.

The concave groove 42 of the sleeve valve member 40 facing the control land portion 411 is the first control chamber R1.
And R2, and the first control chambers R1 and R2 are respectively provided with distribution holes 44 and communicate with the left and right chambers 16a and 16b of the power cylinder 16, respectively.
It is connected to 4. Further, the groove 4 of the sleeve valve member 40
Of the two, those facing the adjustment land portion 412 form the second control chambers R5a and R5b.

A control land portion 41 of the rotor valve member 30.
As shown in FIG. 4, the first chamfer N has a gently inclined first chamfer N at both ends thereof, and two chamfers of a second chamfer u that is steeper than the first chamfer N have two types of chamfers. 412.

Therefore, in the first embodiment of the present invention, as shown in FIGS. 1 to 3, the discharge hole 33A on the downstream side of the adjusting land portion 412 having the second chamfer u has the above-mentioned structure.
The fixed diaphragm 60 is provided in the.

Thus, as shown in FIG. 4, the first
FIG. 5 shows the relationship between the valve opening angle and the opening area of the control land portion 411 of the chamfer N and the adjusting land portion 412 of the second chamfer u taken at three points A, B, and C. As a result of the action of the fixed diaphragm 60, N, u +
A combined area Y by the fixed throttle is obtained, and as a result, as shown in FIG. 6, a two-step bending characteristic in which the flow rate linearly increases with an increase in the rotation angle is obtained.

FIG. 7 is a diagram showing an equivalent circuit formed in the neutral state in the half circumference of FIG. 2, and when the inner inner side of the valve is rotated to the left, the states of the respective throttles N and u are closed and opened. Change. Here, since the diaphragm that changes in the opening direction does not act as a diaphragm, if an equivalent circuit diagram (left cut) is made without a diaphragm, it becomes as shown in FIG.

In FIG. 8, first, the throttle of N starts to act, the supply and discharge of oil in the left and right chambers of the power cylinder 16 is started, and the throttle action of point A in FIG. Then, the throttle of u further acts and the flow of oil to the right chamber increases. This prevents an increase in the flow rate per throttle passage and an increase in abnormal noise caused by the increase in the flow velocity flowing through the throttle passage.

FIG. 9 shows a second embodiment of the present invention. In this second embodiment, the adjusting land portion 41 having the second chamfer u is provided.
The fixed throttle 70 is provided in the supply hole 43A on the upstream side of No. 2. In this case, the equivalent circuit diagram in the neutral state is shown in FIG. 10, and the equivalent circuit diagram when turned counterclockwise as in the first embodiment is shown in FIG. Also in this second embodiment, the flow rate characteristics and the like are obtained in the same manner as in the first embodiment of FIG.

[0020]

As described above, according to the present invention, the supply hole for supplying the pressure fluid, the distribution hole for distributing the pressure fluid supplied from the supply hole to the controlled element, and the discharge of the pressure fluid. And a rotor valve member which are fitted to each other so as to be rotatable relative to each other. The fitting portions of the two valve members include one valve member and a land portion of the other valve member. Between the pressure control land portion provided with a control land for controlling the supply / discharge of the pressure fluid from the supply hole to the distribution hole, and the land portion of one valve member of the other valve member. Pressure characteristic adjusting lands provided with adjusting lands for controlling pressure fluid from the holes to the discharge holes are alternately arranged, and the fitting portion has a plurality of supply chambers and discharge chambers, and between these chambers. Forming a plurality of control chambers located at A first chamfer is formed on the land portion so as to gradually reduce the communication area between the supply chamber and the control chamber with the relative rotation of the valve members, and the land portion for pressure characteristic adjustment is formed with the first chamfer. A second chamfer is formed so that the communication area between the supply chamber and the discharge chamber is gradually increased with the relative rotation of both valve members, and a second chamfer is formed, and a downstream discharge hole or an upstream supply of the second chamfer is formed. Since a fixed throttle is provided in the hole, the throttle area with respect to the rotation angle of the valve is a combined area of the first chamfer and the second chamfer plus the fixed throttle, and only two chamfering operations are required. It is possible to prevent variations in characteristics from occurring.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a power steering apparatus including a rotary servo valve according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a power steering apparatus including a rotary servo valve according to the first embodiment of the present invention.

FIG. 3 is a sectional development view of a main part of a rotary servo valve showing the first embodiment of the present invention.

FIG. 4 is an enlarged sectional view of a chamfered portion showing an embodiment of the present invention.

FIG. 5 is a diagram showing a change in opening area with respect to a valve rotation angle in a rotary servo valve showing an embodiment of the present invention.

FIG. 6 is a flow rate characteristic chart with respect to a rotation angle in a rotary servo valve showing an embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram of the rotary servo valve in the neutral state according to the first embodiment of the present invention.

FIG. 8 is an equivalent circuit diagram of the rotary servo valve according to the first embodiment of the present invention when left-turning.

FIG. 9 is a cross-sectional view of a power steering system including a rotary servo valve according to a second embodiment of the present invention.

FIG. 10 is an equivalent circuit diagram of the rotary type servo valve in the neutral state according to the second embodiment of the present invention.

FIG. 11 is an equivalent circuit diagram of the rotary servo valve according to the second embodiment of the present invention when left-turning.

FIG. 12 is a characteristic diagram of steering pressure with respect to steering wheel torque in a servo valve.

FIG. 13 is a sectional development view of a main part of a rotary servo valve showing a conventional technique.

FIG. 14 is an enlarged detailed cross-sectional view of the chamfered portion of FIG. 13 showing the prior art.

[Explanation of symbols]

 20 rotary servo valve 30 rotor valve member 31 land portion 33 discharge hole 33A discharge hole 40 sleeve valve member 41 land portion 43 supply hole 43A supply hole 60 fixed throttle 70 fixed throttle N first chamfer u second chamfer

Claims (1)

[Claims] 1. A supply hole for supplying a pressure fluid, a distribution hole for distributing the pressure fluid supplied from the supply hole to a controlled element, and a discharge hole for discharging the pressure fluid are formed, which are opposed to each other. It is composed of a sleeve valve member and a rotor valve member that are rotatably fitted to each other, and the fitting portions of these two valve members are provided with the distribution hole from the supply hole between the one valve member and the land portion of the other valve member. Of the pressure fluid from the supply hole to the discharge hole between the pressure control land portion provided with the control land for controlling the supply and discharge of the pressure fluid to and from the land portion of the other valve member in one valve member. Pressure characteristic adjusting lands provided with adjusting lands for controlling are alternately arranged, and a plurality of supply chambers and discharge chambers and a plurality of control chambers located between these chambers are formed in the fitting portion. , Relative to the pressure control land portion of the both valve members A throttle control that gradually reduces the communication area between the supply chamber and the control chamber with rotation
A chamfer is formed, and a second chamfer is formed on the pressure characteristic adjusting land so as to control the throttle so that the communication area between the supply chamber and the discharge chamber is gradually increased with the relative rotation of the valve members, A servo valve, wherein a fixed throttle is provided in a discharge hole on the downstream side or a supply hole on the upstream side of the second chamfer.