JPS6143654Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a power steering device for a vehicle that provides a symmetrical steering sensation when turning left and turning right.

[Prior Art] As shown in FIG. 1, a power steering device supplies pressure fluid from a hydraulic pump 41 to a power cylinder section A via a servo control valve B operated by a steering handle.
The liquid in the other liquid chamber is returned to the liquid tank 42 via the servo control valve B. The servo control valve B sends pressurized fluid to one of the passages 16 and 5 to the power cylinder section A depending on the direction in which the handle is turned. The resistance of the passage inside the control valve can be configured so that it has approximately the same passage resistance when sending pressure fluid to either of the passages 16 and 5 leading to the power cylinder section A, but the resistance of the passage inside the control valve as a whole Since the control valve B is located at one end of the power cylinder section A, the passage resistance of the passage 5 leading to the liquid chamber that is closer to the servo control valve B is small, and the passage 5 is located further away from the control valve B. The resistance of the passage 16 communicating with the liquid chamber 38 on the side tends to increase. Therefore, when you actually operate the steering wheel, one side is heavy and the other side is light, which has an undesirable effect on the steering feel.

[Problems to be solved by the invention] In view of the above-mentioned problems, the invention solves the problem by equalizing the fluid resistance of the pair of passages connecting the servo control valve and the liquid chambers at each end of the power cylinder. An object of the present invention is to provide a power steering device that provides a steering sensation.

[Means for Solving the Problems] In order to achieve the above object, the present invention has a configuration in which a servo control valve is fitted to one end of the casing, and a power cylinder portion in which a piston is fitted to the other end. In a power steering device that generates power for deflecting steering wheels by hydraulic pressure acting on a piston, a hydraulic pressure source is supplied to the servo control valve from one of a pair of liquid chambers partitioned by the piston. a first passage connecting directly to a liquid chamber adjacent to the servo control valve; and a second passage connecting a liquid pressure source through a wall of the casing to a liquid chamber remote from the servo control valve. The second passage has a cross-sectional area such that the fluid resistance thereof is smaller than the fluid resistance of the first passage, and the tip thereof protrudes to the terminal end of the second passage to reduce the flow resistance of the second passage. A fluid resistance adjusting mechanism for making the resistance of the first passage equal to the flow resistance of the first passage is screwed and supported on the casing.

[Operation] The cross-sectional area of the passages 17, 16, and 15 connecting the servo control valve B and the liquid chamber 38 at one end of the power cylinder A is configured to be sufficiently large, and the fluid resistance adjustment mechanism 13 is installed in the middle of this passage. By this, the liquid chamber 39 at the other end of the servo control valve B and the power cylinder A is
It is made equal to the passage resistance of the passage 5 connecting the two. Therefore, the same steering sensation is obtained when the steering wheel is turned to the right and to the left.

[Embodiments of the invention] The configuration of the invention will be described below based on examples. First, as shown in FIG. 2, in the power steering device, a piston 34 is slidably disposed inside a casing 10 formed as a cylinder 43, and the piston 34 is connected to a ball screw shaft 33 via a series of balls 35. They work together to connect the cylinder 43 to the liquid chamber 3.
It is divided into 8 and 39. The piston 34 meshes at a rack 29 with an output gear shaft 28 which is connected to the steering wheels via a conventional Pitman arm and series of linkages. The left end of the casing 10 is an end plate 37 secured with a retaining ring 11.
On the other hand, the right end of the casing 10 is connected to a valve housing 20 by a bolt 18, and this valve housing 20 is closed by a plug 23 screwed into the valve housing 20. A bearing 22 is attached to the plug 23.
A universal joint 25 connected to the handle shaft with
This universal joint 25 is connected to the steering shaft 9 via a spline 24.

The flexible shaft 3 has a pin 30 at the left end of the steering shaft 9.
The proximal ends of the two are joined. The distal end side of the flexible shaft 32 is coupled to the distal end of the ball screw shaft 33 through the hollow portion of the ball screw shaft 33 with the pin 12 .
The tip of the ball screw shaft 33 is supported by the end plate 37 via the thrust bearing 31 so as not to be able to move in the axial direction, while the base end is supported by the aforementioned flexible shaft 32 with the bearing 4.
supports the proximal end of the The outer sleeve 1 is attached with the pin 3 on the base end flange 33a of the ball screw shaft 33.
9 is supported, and on the other hand, the inner sleeve 7 is supported by the aforementioned steering shaft 9 with a pin 8. outer sleeve 1
The right end portion of 9 is rotatably supported by a plug 23 with a thrust bearing 21 .

The outer sleeve 19 and the inner sleeve 7 are arranged concentrically inside the valve housing 20, and relative rotational movement occurs as the flexible shaft 32 twists. The relative rotational movement between both sleeves is achieved by a gear-like member formed on the right end of the flange 33a and the inner sleeve 7.
It is limited by the meshing with an internal gear-like member formed on the inner circumferential surface of the

As is clear from FIGS. 2 and 3, the outer sleeve 19
Grooves 55 and 56 extending in the axial direction are provided on the inner circumferential surface of the radial direction, one of the grooves 55 being connected to the liquid chamber 39 via the inclined radial passage 5, and the other groove 56 being connected to the radial passage 36. and the annular groove 2, and further the passage 17 of the valve housing 20 and the passage 1 of the casing 10.
6 and a passage 15 to a liquid chamber 38 .
An annular groove 6 is provided on the outer circumferential surface of the outer sleeve 19 in line with the annular groove 2, which is connected to the liquid supply port 27 of the valve housing 20, and is connected to the inner sleeve 7 through a radial passage 57 of the outer sleeve 19. It is open on the sliding surface.

On the other hand, an axial groove 4 is formed on the outer peripheral surface of the inner sleeve 7.
5 and 46 are provided, and the groove 45 faces the passage 57 and is always connected thereto, while the groove 46 opens to the inner circumferential side of the inner sleeve 7 through a radial passage 47 and is connected to the steering shaft 9. It passes through the passage with the inner sleeve 7 and the gap between the bearing 21 and is connected to the liquid return port 26 of the valve housing 20 .

When the inner sleeve 7 rotates relative to the outer sleeve 19, the grooves 45, 46 and the grooves 55, 56, which are connected to each other in the neutral position, open one of the liquid chambers 38, 39 depending on the direction of rotation of the handle. is connected to a liquid pressure source, ie, a discharge port of a hydraulic pump 41, and the remaining liquid chamber is controlled to be connected to a liquid tank 42. As is clear from Fig. 2, the liquid supply port 2
In order to obtain liquid tightness between the flow from the liquid chamber 7 to one liquid chamber and the passage from the other liquid chamber to the liquid return port 26,
Three seal rings are mounted on both sides of the annular grooves 2 and 6 of the outer sleeve 19.

Now, when the handle is turned to the right, the liquid supply port 27 is connected to the liquid chamber 38 via the passages 17, 16, and 15 by the control valve B, and the piston 34 moves to the right, causing the output gear shaft to move. 28 to the right and deflects the steering wheels to the right.

On the other hand, when the handle is turned to the left, the liquid supply port 27 is connected to this passage 5 via the control valve B, and pressurized liquid is supplied to the liquid chamber 39. The passage 5 connecting the liquid chamber 39 and the control valve B is connected to the outer sleeve 19 of the control valve.
The passage resistance is low due to its short length. On the other hand, since the passages 17, 16, and 15 connecting the control valve B and the liquid chamber 38 are very long, the passage resistance becomes large.

According to the present invention, the control valve B and each liquid type 38, 39
In order to equalize the passage resistance between the liquid chamber 38 and
The passage cross-sectional areas of the side passages 17, 16, and 15 are configured to be sufficiently large. The terminal end of the axial passage 16 provided in the casing 10, that is, the radial passage 1
A large diameter hole 44 is provided from the outer circumferential side of the casing 10 at the intersection with the passages 16 and 15, and the fluid resistance adjustment mechanism 13 is screwed into the hole 44.
It is designed to adjust the passage resistance. The tip of the fluid resistance adjustment mechanism 13 is tapered and approaches the passage 15, and the passage resistance is adjusted depending on the degree of this approach, thereby forming a passage connecting the control valve B and the liquid chamber 39. 5 and fixed with a lock nut 14. Such setting work is carried out using a load test device at the factory, while actually rotating the steering shaft 9 left and right and observing the amount of rotation and changes in the fluid pressure in each of the fluid chambers 38 and 39.

As explained above, in a power steering device in which a servo control valve is integrally formed at one end of a power cylinder part, the present invention provides a power steering system in which a servo control valve is integrated with a servo control valve at one end of a power cylinder section. , a fluid resistance adjustment mechanism protruding from the outer circumferential wall of the cylinder is screwed and supported, and the amount of protrusion of this fluid resistance adjustment mechanism can be adjusted; therefore, it connects the fluid chambers at both ends of the power cylinder and the servo control valve. The resistance of both passages, which differs depending on the length of the passage, wear, etc., can be set to be equal by adjusting the amount of protrusion of the fluid resistance adjustment mechanism. Since the fluid resistance adjustment mechanism is directly attached to the outer peripheral wall of the cylinder, it can not only be easily adjusted after the power steering device is assembled, but also the link mechanism can be adjusted even after it is assembled to the vehicle. Even if perfect symmetry cannot be obtained in the steering system due to other reasons, the fluid resistance adjustment mechanism provides an excellent effect in that it can be adjusted. Therefore, it is possible to completely eliminate the problem that when the steering wheel is turned to the right or to the left, one side is heavy and the other side is light.

[Effect of the invention] Generally, when the piston moves, hydraulic fluid enters one fluid chamber and is discharged from the other fluid chamber. At this time, the hydraulic fluid enters the power cylinder section and the hydraulic fluid exits. The hydraulic fluids used must be equivalent in various respects. However, in reality, these are not equivalent, so that while the pressure in the liquid chamber on the discharge side increases instantaneously, negative pressure may occur in the liquid chamber on the suction side. This phenomenon causes irregular movement of the piston, which appears as vibrations in the entire power steering system.

According to the present invention, the fluid resistance of the passage connecting the control valve and each liquid chamber of the power cylinder section can be set to be equal, so that the above-mentioned problems can be solved.

In the above-described embodiment, the fluid resistance adjustment mechanism was provided in the passage connecting the control valve and the liquid chamber farther away from the control valve, but it may be provided in the passage connecting the control valve and the liquid chamber adjacent thereto. You can also do it.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a power steering device, FIG. 2 is a longitudinal cross-sectional view of the power steering device according to the present invention, and FIG. 3 is a cross-sectional view showing a schematic configuration of a control valve. A: Power cylinder, B: Servo control valve, 5:
Passage, 7: Inner sleeve, 9: Steering shaft, 10: Casing, 13: Fluid resistance adjustment mechanism, 14: Lock nut, 15, 16, 17: Passage, 19: Outer sleeve, 20: Valve housing, 26: Liquid return port ,2
7: Liquid supply port, 28: Output gear shaft, 32: Flexible shaft,
33: Ball screw shaft, 34: Piston, 38,3
9: Liquid chamber, 41: Hydraulic pump, 42: Liquid tank, 4
3: Cylinder.

Claims (1)

[Claims for Utility Model Registration] A servo control valve is provided at one end of the casing, and a power cylinder portion is fitted with a piston at the other end, and the steering wheel is deflected by the hydraulic pressure acting on the piston. In a power steering device that generates power for the servo control valve, a hydraulic pressure source is directly connected to the one adjacent to the servo control valve of a pair of liquid chambers partitioned by the piston. a first passage and a second passage connecting a hydraulic pressure source through a wall of the casing to a liquid chamber remote from the servo control valve; The cross-sectional area of the passage is smaller than the fluid resistance of the passage, and the tip protrudes to the terminal end of the second passage to make the passage resistance of the second passage equal to the passage resistance of the first passage. A power steering device characterized in that an adjustment mechanism is screwed and supported on the casing.