JPH0642529U - Vehicle power steering device - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the size of the valve drive mechanism and prevent deterioration of steering feeling due to seal friction. [Structure] A stopper 106 is provided above the large-diameter portion 38 separately from the valve driving actuator 15, and the overhanging portion 42 of the valve driving actuator 15 does not have the function of a stopper, and the overhanging portion 42 is formed in a thin plate shape to drive the valve. The actuator 15 is miniaturized to prevent deterioration of steering feeling due to seal friction.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a power steering device for a vehicle used for steering the front wheels of an automobile, for example.

[0002]

[Prior art]

 Some automobiles are equipped with a hydraulic power steering device so that steering can be performed by a driver's light steering operation.

In this power steering device, an input shaft connected to the steering wheel and an output shaft connected to the steered wheels (front wheels) are connected by a torsion bar, and the rotational force of the input shaft is converted to the steering force of the front wheels by intervening a hydraulic assist system. Trying to communicate as.

The assist system is provided with a rotary valve that is displaced relative to the torsion of the torsion bar between the input shaft and the output shaft. An engine-driven oil pump and a power cylinder that drives the front wheels in the steering direction are connected to the rotary valve. Then, the hydraulic pressure obtained by the rotary valve that is relatively displaced by the rotation of the handle is supplied to the power cylinder to generate the assist force.

That is, when the handle is rotated, the output shaft is rotated via the input shaft and the torsion bar. At this time, the rotation of the output shaft is hindered by the road surface resistance of the front wheels, the torsion bar is twisted by the amount of the road surface resistance, and the input shaft rotates by an amount equivalent to the torsion angle of the torsion bar.

As a result, a rotational difference (relative displacement) occurs in the rotary valve provided between the input shaft and the output shaft, and the hydraulic pressure generated by this rotational difference is supplied to the cylinder chamber of the power cylinder. By supplying hydraulic pressure to the power cylinder, the front wheels are steered in the rotation direction of the steering wheel, and the steering force is reduced.

On the other hand, in the conventional power steering device, a reaction mechanism (valve drive mechanism) for generating a reaction force in the assist system and a control valve for controlling the valve drive mechanism are provided, and the response of the steering wheel is hydraulically controlled. It is variable to improve the handle's turning back.

A conventional power steering device will be described with reference to FIGS. 6 and 7. FIG. 6 shows a cross section of a conventional power steering device, and FIG. 7 shows a view taken along the line VII-VII in FIG.

In FIG. 6, reference numeral 2 denotes, for example, a rack and pinion type steering gear that constitutes the steering mechanism 1, and the steering gear 2 has a structure in which a casing 4 has a rack 4 and a pinion 5 built therein.

One end of the rack 4 is connected to one front wheel via a steering rod 6, and the other end is connected to the other front wheel via the steering rod 6 and a power cylinder (not shown).

A lower end of a torsion bar 9 is connected to the pinion 5 of the steering gear 2 via an output shaft (output shaft) 5a. An upper end portion of the torsion bar 9 penetrates a valve unit 10 provided at an upper portion of the steering gear 2 and is connected to an input shaft (input shaft) 11. The input shaft 11 is connected to a handle (not shown) via the steering shaft. When the rotational displacement is input from the steering wheel, the left and right front wheels are steered via the input shaft 11, the torsion bar 9, the pinion 5, the rack 4 and the steering rod 6.

In the valve unit 10, a housing 14 is installed on an upper portion of the steering gear 2 so as to surround the torsion bar 9, and a valve drive actuator (valve driving mechanism) is provided at a portion from the upper portion of the steering gear 2 to the inside of the housing 14. ) 15 and the rotary valve 16 are provided in order from the lower side.

In the rotary valve 16, a cylindrical outer valve 17 is rotatably provided on the inner surface of the housing 14, and a cylindrical inner valve 18 that is combined with the outer valve 17 is integrally provided on the input shaft 11. In other words, the rotary valve 16 is configured such that when the torsion bar 9 is twisted by the rotating operation from the handle, a relative displacement is generated between the outer valve 17 and the inner valve 18.

An inflow port 17 a formed in the outer valve 17 communicates with an inflow port body 19 provided in the housing 3, and an outflow port 18 a formed in the inner valve 18 is an outflow port body provided in the housing 3. It communicates with 20. An output port (not shown) formed in the outer valve 17 communicates with a pair of output port portions 21 and 22 provided in the housing 3. The output port units 21 and 22 are connected to a power cylinder (not shown).

When the outer valve 17 and the inner valve 18 of the rotary valve 16 are relatively displaced, the hydraulic circuit supplies hydraulic pressure corresponding to the steering force and the steering direction from the rotary valve 16 to the power cylinder. In other words, the front wheels are steered while being hydraulically assisted.

Here, the valve drive actuator 15 will be described with reference to FIGS. 6 and 7. FIG. 7 shows a view taken along the line VII-VII in FIG.

An extension portion 37 is formed at a lower end portion of the input shaft 11 (a shaft portion immediately below the inner valve 18), and the extension portion 37 has a lower end portion of the input shaft 11 that extends downward along the axial direction of the torsion bar 9. Has been extended to. The casing 3 around the extension portion 37 has a large diameter portion, and a circular chamber 47 is formed in the large diameter portion. A hollow circular large-diameter portion 38 integrally connected to the output shaft 5a is rotatably accommodated in the chamber 47. The large diameter portion 38 is connected to the outer valve 17 of the rotary valve 16 via the pin 36.

A sleeve 39 is press-fitted onto the outer circumference of the large diameter portion 38, and the sleeve 39 is fitted in the chamber 47 of the casing 3. Three seal rings 53 are attached to the outer peripheral surface of the sleeve 39 in the axial direction, and are sealed by the seal rings 53 at three locations.

On the other hand, as shown in FIG. 7, inside the large-diameter portion 38, there are two symmetric points 180 degrees apart from each other in the through-hole 38 a (FIG. 6) of the large-diameter portion 38. A flat concave-shaped chamber 41 extending outward in the radial direction is formed.

In the extended portion 37 covered with the large diameter portion 38, a plate-shaped overhanging portion 42 (pressed portion 42) that extends outward in the radial direction from two symmetrical points 180 degrees apart in the circumferential direction. ) Are formed respectively. Each of the overhanging portions 42 is formed to have an outer shape smaller than the length and width dimensions of the chamber 41, and the overhanging portions 42 are concentrically loosely fitted in the chamber 41.

The gap between the plate-shaped overhanging portion 42 and the flat chamber 41 is set to a dimension that can set a region necessary to compensate the operating angle of the rotary valve 16, and the torsion bar 9 is positioned relative to the input shaft 11. It can be twisted within a predetermined angle range. Further, since the overhanging portion 42 also serves as a stopper that regulates the displacement amount of the rotary valve 16, the width dimension of the overhanging portion 42 has a strength as a stopper.

Two circular hole portions 43 are formed in the large diameter portion 38 on both sides of the chamber 41 so as to sandwich the overhanging portion 42 and are connected in series. Plungers 44a and 44b (pressers) are slidably inserted in the respective hole portions 43 in the axial direction, and the plungers 44a and 44b are extended by valve seats 40a and 40b and springs 53a and 53b. 42 is energized.

A first hydraulic chamber 45 is formed in one of the valve seats 40 a, 40 b (the side that presses the overhanging portion 42 in the clockwise direction), and the other valve seat 40 a, 40 b (the overhanging portion 42 is counterclockwise). A second hydraulic chamber 46 is formed on the side that presses in the circumferential direction). The casing 3 is provided with a first inlet body 54 and a second inlet body 55, the first inlet body 54 communicates with the first hydraulic chamber 45, and the second inlet body 55 communicates with the second hydraulic chamber 46. .

The first inlet body 54 and the second inlet body 55 are connected to a hydraulic circuit (not shown), and the plungers 44a and 44b are driven by supplying a predetermined hydraulic pressure to press the overhanging portion 42 to the torsion bar 9. Independently generate a twisting moment.

By controlling the hydraulic pressure supplied to the first inlet body 54 and the second inlet body 55, the assist force obtained by rotating the rotary valve 16 in the same direction as the torsion direction of the torsion bar 9 and the torsion bar. The assist force obtained by rotating the rotary valve 16 in the direction opposite to the twisting direction of 9 is generated. As a result, the variable range of the steering force can be remarkably widened, the burden on the driver at the time of stationary steering back can be significantly reduced, and the steering force according to the driving conditions can be obtained.

The assembly state of the plungers 44a and 44b will be described with reference to FIG. FIG. 8 shows an exploded perspective view of the valve drive actuator 15.

Pre-processing such as slotting and quenching is performed on the sleeve 39, and the sleeve 39 is press-fitted onto the outer circumference of the large diameter portion 38 of the output shaft 5a. The valve seats 40a and 40b, the springs 53a and 53b, and the plungers 44a and 44b are inserted from the chamber 41 side into the hole 43. The seal ring 53 is attached to the outer circumference of the sleeve 39. Therefore, the width of the chamber 41 is dimensioned so that the plungers 44a, 44b and the like can be inserted therein.

[0028]

[Problems to be solved by the device]

 In the conventional power steering device, since the overhanging portion 42 formed at the lower end of the input shaft 11 of the valve drive actuator 15 also functions as a stopper that restricts the displacement amount of the rotary valve 16, the overhanging portion 42 has a width dimension. It needed a size that was strong enough as a stopper. Therefore, there is a limit to the size reduction of the valve drive actuator 15, and the sleeve 39 has a large diameter, which may deteriorate the steering feeling due to the seal friction.

[0029]

[Means for Solving the Problems]

 The configuration of the present invention for solving the above problems is a steering mechanism in which an output shaft connected to a steering wheel is connected to one end of a torsion bar and an input shaft connected to a handle is connected to the other end of a torsion bar. Between a rotary valve that is provided between the input shaft and the output shaft and outputs relative force according to the torsion of the torsion bar during steering operation to output an assist force, and between the input shaft and the output shaft of the steering mechanism. Is provided on one of the input shaft and the output shaft, and the other is provided with a presser for pressing the pressed part along both sides in the circumferential direction of the shaft. A valve drive mechanism that independently generates a torsional moment with respect to the torsion bar, and a stopper that restricts the relative displacement of the rotary valve is provided in the valve drive mechanism. It characterized in that the provided separately to said input shaft or said output shaft.

[0030]

[Action]

 The relative displacement of the rotary valve is restricted by a stopper provided separately from the valve drive mechanism, and the valve drive mechanism only has the function of generating a torsion moment in the torsion bar.

[0031]

【Example】

 1 is a sectional view of a steering mechanism of a power steering apparatus according to an embodiment of the present invention, FIG. 2 is a view taken along the line II-II in FIG. 1, and FIG. 3 is a view taken along the line III-III in FIG. Is shown. The same members as those shown in FIGS. 6 to 8 are designated by the same reference numerals, and duplicate explanations are omitted.

A small-diameter step portion 101 is formed below the large-diameter portion 38 of the output shaft 5 a, and the outer periphery of the step portion 101 is sealed by a seal ring 102.

A sleeve 103 as a valve body is fitted by fitting on the outer circumference of the large diameter portion 38, and the outer circumference of the sleeve 103 is fitted in the chamber 47 of the casing 3. Seal rings 53 are attached to the outer peripheral surface of the sleeve 103 at two axial positions, and the space between the sleeve 103 and the chamber 47 is sealed by the two seal rings 53.

A pin 104 (for example, a dowel pin) is engaged between the lower portion of the large diameter portion 38 and the sleeve 103, and the pin 104 fixes the sleeve 103 in the rotational direction. A C-shaped retaining ring 105 is engaged between the upper part of the large diameter portion 38 and the sleeve 103, and the C-shaped retaining ring 105 fixes the sleeve 103 in the axial direction. That is, the pin 104 and the C-shaped retaining ring 105 form a position fixing pin.

As shown in FIG. 3, a stopper 106 is formed above the large diameter portion 38 of the output shaft 5 a, and a portion of the stopper 106 is connected to the outer valve 17 of the rotary valve 16 by a pin 36. The gap between the input shaft 11 and the stopper 106 is set to a size that compensates for the operating angle of the rotary valve 16, and when the input shaft 11 contacts the stopper 106, the maximum torsion moment is generated in the torsion bar 9. .

By forming the stopper 106 on the upper portion of the large diameter portion 38, the width dimension of the overhang portion 42 may be such that a torsion moment can be generated in the torsion bar 9, and the overhang portion 42 is formed in a thin plate shape. You can

The assembly status of the plungers 44a and 44b will be described with reference to FIG. FIG. 4 shows an exploded perspective view of the valve drive actuator.

Plungers 44a and 44b, springs 53a and 53b, and valve seats 40a and 40b are inserted into the hole 43 from the outer peripheral side of the large diameter portion 38 of the output shaft 5a. After that, the sleeve 103 is fitted on the outer circumference of the large diameter portion 38, and the pin 103 fixes the sleeve 103 in the rotation direction, and the C-shaped retaining ring 105 fixes the sleeve 103 in the axial direction.

In the power steering apparatus described above, the sleeve 103 of the valve drive actuator and the large diameter portion 38 are fitted by fitting, and the pin 104 and the C-shaped retaining ring are used to fix the position. The plungers 44a, 44b and the like can be inserted from the outside of the large diameter portion 38 before fitting. Therefore, the shapes of the plungers 44a, 44b and the like and the shape of the chamber 41 are not restricted by each other, the length of the plungers 44a, 44b can be increased, and the width of the chamber 41 can be set to the minimum required width. It is possible to disassemble and assemble easily.

Further, since the stopper 106 is formed on the upper portion of the large-diameter portion 38, the overhanging portion 42 does not need to have the function of a stopper, and the overhanging portion 42 can be formed in a thin plate shape. For this reason, the large-diameter portion 38 can be made smaller in size in combination with the width of the chamber 41 being made smaller, and the steering mechanism can be made smaller.

Further, since the sleeve 103 is sealed by the two seal rings 53 in the axial direction, the influence of the seal friction on the steering feeling can be reduced.

As shown in FIG. 5, a step portion 110 is formed on the casing 3 above the large diameter portion 38 of the output shaft 5 a, and the step portion 110 and the large diameter portion 38 are sealed by a sealing ring 111. By sealing, the sleeve 103 can be sealed at one place, and the seal friction can be further reduced.

[0043]

[Effect of device]

 In the power steering device of the present invention, the input shaft or the output shaft is provided with a stopper for restricting the relative displacement of the rotary valve in addition to the valve drive mechanism, so that the valve drive mechanism generates a torsion moment in the torsion bar. Only the function needs to be provided, and the valve drive mechanism can be downsized. As a result, the seal of the valve drive mechanism becomes smaller, and it is possible to prevent deterioration of steering feeling due to seal friction.

[Brief description of drawings]

FIG. 1 is a sectional view of a steering mechanism of a power steering device according to an embodiment of the present invention.

FIG. 2 is a view taken along the line II-II in FIG.

3 is a view taken along the line III-III in FIG.

FIG. 4 is an exploded perspective view of a valve drive actuator.

FIG. 5 is a sectional view of a steering mechanism of a power steering device according to another embodiment of the present invention.

FIG. 6 is a sectional view of a steering mechanism of a conventional power steering device.

FIG. 7 is a view taken along the line VII-VII in FIG.

FIG. 8 is an exploded perspective view of a valve drive actuator.

[Explanation of symbols]

 1 Steering Mechanism 3 Housing 5a Output Shaft 9 Torsion Bar 11 Input Shaft 15 Valve Drive Actuator 16 Rotary Valve 17 Outer Valve 38 Large Diameter 39 Sleeve 42 Overhang 43 Hole 44a, 44b Plunger 53 Seal Ring 101 Step 102 Seal Ring 103 Sleeve 104 Pin 105 C-shaped retaining ring 106 Stopper

Claims (1)

[Scope of utility model registration request] 1. A steering mechanism in which an output shaft connected to a steered wheel is connected to one end of a torsion bar and an input shaft connected to a steering wheel is connected to the other end of the torsion bar, and the input shaft and the output shaft are connected. A rotary valve, which is provided between the input shaft and the output shaft of the steering mechanism, and a rotary valve that relatively displaces according to the twist of the torsion bar during steering operation to output an assist force, and a rotary valve that is provided between the input shaft and the output shaft of the steering mechanism. A pusher is provided on one side and a pusher is provided on the other side to push the pushed part along both sides in the circumferential direction of the shaft, and a twisting moment is independently applied to the torsion bar by driving the pusher. A valve drive mechanism for generating a stopper for restricting the relative displacement of the rotary valve is provided on the input shaft or the output separately from the valve drive mechanism. A vehicle power steering device characterized by being provided on a shaft.