JPS6129574Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a hydraulic boost steering device in which a servo control valve is disposed in one of the liquid chambers of a power cylinder.

[Conventional technology]

In a conventional hydraulic booster steering device, the outer sleeve of a rotary servo control valve is provided with one valve hole and a pair of valve grooves, and one of the valve hole and the valve groove is provided with an annular groove provided in the valve chamber, respectively. It is designed to communicate with the hydraulic pump discharge port and one of the liquid chambers of the power cylinder through the groove and the passage provided in the cylinder body.
At least three seal members between the valve chamber and the outer sleeve to obtain liquid tightness between each annular groove, and the outer periphery of the piston and a ball screw to obtain liquid tightness between the liquid chambers at both ends of the power cylinder. It requires two sealing members disposed in the shaft penetrating portion, the passage in the cylinder wall is long and complicated, and its machining requires a lot of labor and time, which is disadvantageous in terms of cost.

Furthermore, the outer sleeve is formed integrally with the end of the ball screw shaft, and the inner sleeve is formed integrally with the steering shaft. A hydraulic steering booster has been proposed that has a passage connected to one cylinder liquid chamber and a passage connected to the liquid tank, but a seal ring is attached to the torsion bar to ensure liquid tightness between the two passages. This reduces the sensitivity of the servo control valve, makes it difficult to replace the seal ring, and makes it difficult to cut a valve groove on the inner circumferential surface of the outer sleeve that is integral with the ball screw shaft. There is a problem in that about six seal rings are required to obtain liquid tightness between the passages connected to the cylinder liquid chamber.

[Problem that the invention attempts to solve]

The purpose of the present invention is to provide a hydraulic double-pressure pump with a simple structure for sealing a pair of liquid chambers in a power cylinder and a passage connecting the control valve and the liquid chamber, making the entire device compact, and making it easy to process and assemble parts. The purpose of the present invention is to provide a power steering device.

[Means to solve the problem]

In order to achieve the above object, the present invention has a configuration in which a control valve is disposed in one of a pair of liquid chambers partitioned by a piston fitted into a cylinder, and the control valve is connected to a ball screw shaft screwed into the piston. a cylindrical first valve element coupled to the ball screw shaft; and a steering shaft coupled to the ball screw shaft with a flexible shaft and the first valve element coupled to the
a cylindrical second valve element that fits into the valve element, the first valve element crossing one of the pair of liquid chambers and having both ends connected to the end wall of the cylinder and the cylindrical portion of the piston. is rotatably supported by the first
A radial passage is provided in the first valve element that directly connects a first valve groove provided in the valve element to one of the pair of liquid chambers; The valve groove is passed through the inside of the cylindrical portion of the piston to the first
An axial passage consisting of a hole connected to the other of the pair of liquid chambers is provided inside the first valve element.

[Effect]

As the outer sleeve 6 and the inner sleeve 2 are selected in advance from parts that can provide an optimal fit and are coupled to the ball screw shaft 10 and the steering shaft 1, respectively, assembly is easy. The outer sleeve 6 is rotatably supported by the cylindrical portion of the piston 12 and the shaft hole of the end wall of the cylinder 13 via seal members 56 and 50, respectively, and the liquid chamber B housing the control valve is connected to the other side by the seal members. It is sealed with liquid chamber A. A passage connecting the control valve and the other liquid chamber formation A is connected to the ball screw shaft 10 from a passage 28 consisting of a hole provided inside the outer sleeve 6.
Since the passage is communicated through the threaded part, the structure of the passage is simple and processing is easy.

[Example of idea]

The present invention will be described below with reference to embodiments shown in the drawings. As shown in FIG. 1, in the booster steering device, first, a piston 12 having a rack 18 on a part of its outer periphery is fitted into a cylinder 13 that is closed by an end wall plate 17 and a stopper 46. A gear shaft 19 that transmits deflection power to the steering wheel is meshed with the gear shaft 19, and a hollow ball screw shaft 10 is screwed into the axial center of the piston 12 via a ball 11.
The tip of the steering shaft 1 is supported relatively rotatably through a bearing 15 in the hollow part of the base end of the ball screw shaft 10, and the flexible shaft 8 is inserted into the hollow part of the ball screw shaft 10, and the tip is held with a pin 44. The tip of the ball screw shaft 10 is rotatably connected, the base end is rotatably connected to the steering shaft 1 with the pin 3, the tip of the ball screw shaft 10 is supported on the cylinder end wall by a thrust bearing 43, and the steering shaft 1 is connected to the bearing. When the steering shaft 1 is rotated, the two control valves are rotated by utilizing the torsion of the flexible shaft 8 caused by the drag force of the steering wheel which the ball screw shaft 10 receives when the steering shaft 1 is rotated. A rotational differential is generated between the valve elements, hydraulic pressure is applied to one of the cylinder chambers A and B divided into two by the piston 12, and the ball screw shaft 1
This is to push the piston 12 in a direction that facilitates the rotation of the piston 12.

Then, the control valve is connected to the piston 12 and the end wall plate 17.
It consists of a pair of valve elements consisting of an outer sleeve 6 and an inner sleeve 2, which are arranged in a cylinder chamber B defined by are rotatably coupled to the steering shaft 1 by extension portions of the .

In order to guide and support the rotation of the outer sleeve 6, as shown in FIG. Both ends of the outer sleeve 6 are fitted into 47 and 54. The left end of the outer sleeve 6 is fitted over the base end of the ball screw shaft 10 and abutted against the flange 10a, so that the ball screw shaft 10 and the outer sleeve 6 are connected to the aforementioned thrust bearing 4.
3 and a thrust bearing 14 supporting the right end portion of the outer sleeve 6, the outer sleeve 6 rotates integrally without moving in the axial direction.

The thrust shaft 14 is supported between the right end surface of the outer sleeve 6 and the inner end surface of a plug 46 screwed into the side wall plate 17.

To explain in detail the structure of the outer sleeve 6 and the inner sleeve 2, which are valve elements, as shown in FIGS. 2 and 3, the outer sleeve 6 has radial liquid holes 22a, 23a, and 24a at different positions in the circumferential direction. drilled. The outer peripheral end of the liquid hole 22a is connected to the annular groove 22 of the cylindrical portion 54 mentioned above which is connected to the liquid supply port 20, and the inner end of the liquid hole 23a is connected to the communication groove 23 cut in the inner periphery and extending in the axial direction.
The outer end is connected to the liquid path 28, and the liquid hole 24a is also connected to the liquid passage 28.
The inner end is directly connected to the communication groove 24, and the outer end is directly connected to the liquid chamber B. The liquid passage 28 extends in the axial direction of the outer sleeve 6, passes through the flange 10a of the ball screw shaft, is connected to the inside of the cylindrical portion 47 of the piston described above, and further extends into the gap between the threaded portion of the piston 12 and the ball screw shaft 10. It is connected to the liquid chamber A through the .

The inner sleeve 2 has control grooves 25 and 26 cut in the outer circumference at different positions in the circumferential direction and extending in the axial direction, and in particular, the control groove 26 communicates with the inner circumference through a radial liquid hole 26a. , communicates with the bearings 15, 14, 35 through a circumferential distance from the steering shaft 1, and further communicates with the liquid return port 21.
is connected to.

Then, both the inner and outer sleeves 2 and 6 are in the neutral position.
In other words, when the flexible shaft 8 is not twisted,
The control groove 25 allows the liquid hole 22a to communicate with the communication grooves 23 and 24, and the control groove 26 allows the communication groove 23 and 24 to communicate with the liquid hole 26a.

In order to obtain liquid tightness between the liquid chambers A and B partitioned by the piston 12, a seal ring 48 is provided on the outer circumference of the piston that makes sliding contact with the cylinder 13.
A seal ring 56 is attached to the cylindrical portion 47 that makes sliding contact with the liquid chamber B, and the seal ring 50 is attached to provide liquid tightness between the annular groove 22 connected to the liquid supply port 20 and the liquid chamber B, and between the annular groove 22 and the bearing 14 side. Seal rings 51 for obtaining liquid tightness are attached to the cylindrical portions 54 of the side wall plates 17, respectively.
will be installed on the

Note that 49 and 52 are seal rings provided at the assembly portions of the side wall plate 17 and the plug 46, and 55 is a seal ring for the bearing portion of the steering shaft 1.

Next, the operation of the hydraulic booster steering device having the above configuration will be explained. Figures 1 to 3 show the neutral state of the booster steering system (vehicle is running straight), and at this time, the pressurized fluid enters the fluid groove 25 from the fluid supply port 20 through the annular groove 22 and the fluid hole 22a. From here, the liquid groove 24, liquid hole 24
While entering the liquid chamber B through a, the liquid groove 23 and the liquid hole 23
a, enters the liquid chamber A via the liquid path 28, and enters the piston 12
The liquid grooves 24 and 23 also enter the gap between the inner sleeve 2 and the steering shaft 1 through the liquid groove 26 and the liquid hole 26a, and the bearings 15, 14, 35
Since the liquid returns to the return port 21, the liquid pressure acting on the piston 12 is extremely low due to liquid path resistance, and since the pressure is the same on the left and right sides, the piston 12 has no thrust. does not occur.

If you turn the handle to the right now, the ball screw shaft 10
is receiving a drag force from the steering wheels, so only the steering shaft 1 is rotated with the twisting of the flexible shaft 8, and the inner sleeve 2 is rotated in the hour hand direction (the third direction) with respect to the outer sleeve 6.
(Figure) produces a rotational differential. Therefore, the liquid grooves 25, 2
4 and between the liquid grooves 23 and 26 are closed, and the liquid grooves 25 and 2 are closed.
3 and between the liquid grooves 24 and 26, the pressure liquid from the liquid supply port 20 is transferred to the annular groove 22, the liquid hole 22a, the liquid groove 25, the liquid groove 23, the liquid hole 23a, the liquid path 28, the cylindrical part 47, The liquid in the cylinder liquid chamber A enters the cylinder liquid chamber A through the threaded part of the ball screw shaft 10 and exerts liquid pressure on the left end of the piston 12, while the liquid in the cylinder liquid chamber B flows through the liquid hole 24a, the liquid groove 24, the liquid groove 26, and the liquid hole. 26a, the bearings 15, 14, 35 pass through the gap between the inner sleeve 2 and the steering shaft 1.
The liquid is lubricated and returned to the liquid tank (not shown) through the return port 21. Since the ball screw shaft is a right-handed screw shaft, the rightward movement of the piston 12 facilitates the clockwise rotation of the ball screw shaft by applying a slight rotational force that causes twisting to the flexible shaft 8. The gear shaft 19 is rotated in the hourly direction by hydraulic power, and the steering wheel is deflected to the right via a Pitman arm and a link mechanism (not shown).

Such a hydraulic circuit only occurs during the period of twisting of the flexible shaft 8, during which the deflection angle of the wheels increases. When the required deflection angle is reached, if the rotation of the steering shaft 1 is stopped, the movement of the piston 12 is controlled by the flexible shaft 8.
moves to a position where it untwists, and then
The relationship between the outer sleeve 6 and the inner sleeve 2 is in the neutral state shown in FIG. 3, and the gear shaft 19 makes a servo movement to the steering shaft 1.

Next, when the steering shaft 1 is rotated to the left together with the steering wheel, a hydraulic pressure circuit is formed in the opposite direction to the case where the steering shaft 1 is rotated to the right as described above, but the effect is exactly the same, so we will not explain it. Omitted.

[Effect of idea]

Since the present invention is configured as described above, it has the following effects.

(1) Since the control valve is arranged inside one of the liquid chambers, the overall length of the device as a whole is shortened, and the control valve itself can be arranged compactly.

(2) Since the control valve is placed in one of the liquid chambers, the length of the passage connecting each liquid chamber is short, machining is simple, the fluid resistance of the passage is small, and power loss is reduced.

(3) By rotatably supporting both ends of the outer sleeve 6 on the piston 12 and the end wall of the cylinder 13, one liquid chamber B (relative to the other liquid chamber A)
Sealing is achieved with only two seal members 56, 50, which not only facilitates assembly and replacement, but also reduces rotational friction torque of the control valve.

(4) Since the outer sleeve 6 and the inner sleeve 2 are configured separately from the ball screw shaft 10 and the steering shaft 1, the ball screw shaft 10 is
and can be coupled to the steering shaft 1.

(5) Since the outer sleeve 6 and the inner sleeve 2 are constructed separately from the ball screw shaft 10 and the steering shaft 1 and are supported by these, it is easy to manage the machining accuracy and assembly accuracy of each valve element. Moreover, since the outer sleeve 6 and the inner sleeve 2 are supported in a floating manner, the rotational sliding movement between them is extremely smooth, and an excellent steering feeling can be obtained.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of a hydraulically powered steering device according to the present invention, FIG. 2 is an enlarged sectional view of the main part of the device, and FIG.
The figure is a cross-sectional view for explaining the operation of the device. 1: steering shaft, 2: inner sleeve, 6: outer sleeve, 8: flexible shaft, 10: ball screw shaft, 12: piston, 13: cylinder, 20: fluid supply port, 21:
Liquid return port, 22: annular groove, 50, 51: sealing members, 40 to 42: annular groove, 17: end wall plate, 19:
Gear shaft, 28: fluid passage, 48, 56: sealing members.

Claims (1)

[Claims for Utility Model Registration] A control valve is disposed in one of a pair of liquid chambers partitioned by a piston fitted into a cylinder, and the control valve has a cylindrical shape connected to a ball screw shaft screwed into the piston. a cylindrical second valve element connected to a steering shaft connected to the ball screw shaft with a flexible shaft and fitted into the first valve element; The first valve element traverses one of the pair of liquid chambers and is rotatably supported at both ends by the end wall of the cylinder and the cylindrical portion of the piston, and a first valve element provided on the first valve element The valve groove is
a radial passageway directly connected to one of the pair of liquid chambers is provided in the first valve element; A hydraulic booster steering device characterized in that an axial passage consisting of a hole connected to the other of the pair of liquid chambers is provided inside the first valve element.