JP3126753B2 - Ball screw type steering device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved ball screw type steering apparatus having a ball screw supported on a housing via a four-point contact type ball bearing.

[0002]

2. Description of the Related Art As a ball screw type steering device, Japanese Patent Laid-Open Publication No. 55-44012 and Japanese Utility Model Publication No. 60-2
There is one disclosed in Japanese Patent No. 4680 or the like. The steering device includes a ball screw supported on a housing via a four-point contact ball bearing, a ball nut fitted to the ball screw, a sector gear meshing with a rack formed on the ball nut, and the sector gear. And an output shaft that is integrated with the steering wheel. The bearing is a mating outer ring angular ball bearing in which the inner ring is formed integrally with a ball screw and the outer ring has its track separated into two on a plane perpendicular to the center axis of the bearing. Are inserted into pockets formed to extend radially through the annular retainer.

In such a steering device,
By supporting the ball screw via a four-point contact type ball bearing, not only a radial load acting on the ball screw but also an axial load is received. Therefore, if the diameter of the ball of the bearing is inappropriate, the ball screw will rattle in the axial direction, which will rattle the steering wheel.

Therefore, when assembling the above-described ball screw type steering apparatus, several kinds of balls having different diameters are prepared in advance, and an appropriate ball diameter is determined by repeating disassembly and assembly.

[0005]

In the four-point contact type ball bearing, since the ball race grooves of the inner ring and the outer ring are deepened in order to receive a sufficient axial load, the distance between the corresponding shoulders of the inner and outer rings is reduced. In addition, the thickness of the cage disposed between the inner and outer rings must be reduced. As a result, the balls are easily scattered radially outward from the pockets of the retainer and fall off, making it difficult to disassemble and assemble, and the dropped balls sometimes enter between the sector gear and the rack.

An object of the present invention is to provide a ball screw type steering device which can solve the above-mentioned problems of the prior art.

[0007]

SUMMARY OF THE INVENTION The features of the present invention include a ball screw supported on a housing via a four-point contact type ball bearing, a ball nut fitted to the ball screw, and a ball nut. A sector gear meshing with the formed rack, and an output shaft integrated with the sector gear and interlocking with the steering wheel are provided. The inner ring of the bearing is integrally formed with a ball screw, and the ball of the bearing is annular. In a ball screw type steering device inserted into a pocket formed so as to penetrate the retainer in the radial direction, the retainer prevents the ball from coming out of the pocket in the radial direction and has a radially inward direction. A claw projecting outward in the radial direction is provided so as to allow the claw to escape, and the claw is
It is elastically deformable so as to allow the ball to be pushed into the pocket from the outside in the radial direction. is a possible dimensions prevent the ball escaping outward radial direction from the pocket when the pull, the cage relative to the inner ring
Bolts held in pockets when pulled out axially outward
At the point where the tool exits radially inward .

[0008]

In order to assemble the four-point contact type ball bearing in the configuration of the present invention, first, an annular cage is fitted to an inner ring integrated with a ball screw, and then the ball is pushed into a pocket of the cage. At this time, the ball is inserted into the pocket due to the elastic deformation of the claw formed on the retainer. The balls inserted into the pockets of the retainer are prevented from coming off in the radial direction by the claws, so that the assembling can be performed smoothly. Thereafter, the outer ring is attached to complete the assembly of the ball bearing.

In order to disassemble the ball bearing, first, the outer ring is removed, and then the cage is removed from the inner ring in the axial direction. At this time, the ball inserted into the pocket of the retainer is pushed by the outer peripheral surface of the inner race and moves radially outward, but is prevented from coming out of the pocket radially outward by the claw. When the cage is withdrawn from the inner ring in the axial direction, the ball held in the pocket of the cage escapes radially inward. That is, since all the balls of the bearing escape radially inward of the annular retainer, they are not dispersed and the bearing can be easily disassembled.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

The ball screw type steering apparatus shown in FIG. 1 includes an input shaft 2 connected to a steering wheel of a vehicle, and a ball screw 4 connected to the input shaft 2 via a torsion bar 3. The torsion bar 3 is connected to the input shaft 2 via a pin 5 and to the ball screw 4 via a serration 6. The input shaft 2 is inserted into the housing 8 via the dust seal 7, is rotatably fitted to the housing 8 via the roller bearing 15, and is further connected to the ball screw 4 via the bush 9.
Are fitted so as to be relatively rotatable. The ball screw 4 is supported by the housing 8 via a four-point contact type ball bearing, for example, a mating outer ring angular ball bearing 10. A large number of balls 25
The ball nut 11 is fitted through the
1, a rack 12 is formed. An output shaft 14 is integrated with a sector gear 13 that meshes with the rack 12. A pitman arm (not shown) is attached to the output shaft 14, and the pitman arm is connected to a steering wheel via a link.

Thus, the input shaft 2 can be controlled by the steering operation input.
When the input shaft 2 rotates, the rotation of the input shaft 2
The ball nut 4 is transmitted to the ball screw 4 via the ball screw 4, and the rotation of the ball screw 4 causes the ball nut 11 to move in the axial direction. The rack 12 moves along with the ball nut 11, and the output shaft 14 integrated with the sector gear 13 meshing with the rack 12 rotates. The rotation of the output shaft 14 steers the steering wheel.

A pair of oil chambers 16, 17 partitioned by a ball nut 11 are formed inside the housing 8 in order to provide an assisting force for the steering operation.
A known control valve 18 that operates according to the torsion angle of the torsion bar 3 is provided to supply pressure oil according to the steering direction and the steering resistance.

The control valve 18 has a cylindrical valve member 19 surrounding the input shaft inside the housing 8.
It has. The valve member 19 is connected to the ball screw 4 so as to rotate together. The control valve 18 is connected to an inlet port 20 connected to a pump (not shown).
, An outlet port 21 connected to a tank (not shown), a first port 22 connected to one oil chamber 16, and the other oil chamber 1
7 is connected to the second port 23. The ports 20, 21, 22, and 23 communicate with each other through a flow path between the input shaft 2 and the valve member 19, and the flow path is connected to the torsion bar 3.
The opening is adjusted by the relative rotation between the input shaft 2 and the valve member 19 due to the torsion. In other words, in the straight traveling state, the torsion angle of the torsion bar 3 is 0 because there is no steering resistance.
The inlet port 20 and the outlet port 21 communicate with each other, and the pressure oil supplied from the pump to the control valve 18 returns to the tank, so that the oil pressure does not act on the ball screw 11. When the steering resistance increases after steering, the torsion bar 3 is twisted according to the steering resistance, and the valve member 19 integrated with the ball screw 4 rotates relative to the input shaft 2. Then, the degree of opening of the flow path between the inlet port 20 and the outlet port 21 decreases, and the oil chamber 1
Oil having a pressure according to the steering direction and the steering resistance is supplied to one of the oil chambers 6 and 17, and the oil flows from the other of the oil chambers 16 and 17 to the tank through the outlet port 21. As a result, a steering assist force corresponding to the steering direction and the steering resistance acts on the ball nut 11.

In the mating outer ring angular ball bearing 10, the inner ring 30 is formed integrally with the ball screw 4. As a result, the steering device has a reduced number of parts, a reduced radial dimension,
Since a retaining ring for preventing the movement in the axial direction is unnecessary, the axial dimension is also reduced.

The outer race 31 of the ball bearing 10 is
The track is divided into a first member 31a on one axial side and a second member 31b on the other axial side in a plane perpendicular to the center axis of the bearing.
It is divided into two parts. The outer ring 31 is pressed against the inner surface of the housing 8 by a ring-shaped lock screw 32 screwed into the housing 8.

The inner ring 30 and the outer ring 31 of the bearing 10
An annular retainer 34 is disposed between the annular retainer 34 and, as shown in FIGS. 2 to 4, a ball 33 is inserted into circumferentially equally spaced pockets 35 formed to penetrate the annular retainer 34 in the radial direction.
Is inserted. Each ball 33 has an inner circumferential groove 30 ′ of the inner race 30.
The bearing 10 supports the radial load and the axial load acting on the ball screw 4 by contacting at two points with the inner peripheral groove 31 ′ of the outer ring 31.

The retainer 34 has a claw 36 projecting radially outward so as to prevent the ball 33 from coming out of each pocket 35 in the radial direction and allow the ball 33 to come out in the radial direction. Is provided. Each claw 36 is located at the axial center of the holder 34 and between the pockets 35 and
4 and the end is projected toward the pocket side, so that each claw 36 is, as shown by a broken line in FIG. Touch the surface.

Each of the claws 36 is provided with a pocket 35 from the outside in the radial direction.
The ball 33 is elastically deformable so as to allow the ball 33 to be pushed into the inside. In this embodiment, the claw 36 is elastically deformable together with the retainer 34 by being integrally formed of a synthetic resin having elasticity. Thereby, as shown by an arrow A in FIG. 5, the ball 33 can be pushed into the pocket 35 from the outside in the radial direction of the retainer 34.

The size (S in FIG. 4) of each claw 36 projecting radially outward from the outer peripheral surface of the retainer 34 is determined when the retainer 34 holding the ball 33 is pulled out from the inner ring 30 in the axial direction. In addition, the ball 33 is dimensioned to prevent the ball 33 from coming out of the pocket 35 in the radial direction. That is, when the retainer 34 is pulled out in the axial direction with respect to the inner ring 30 as shown in FIG.
The ball 33 is pushed by the outer peripheral surface of the inner ring 30 and moves radially outward. At this time, the claw 36 prevents the ball 33 from coming out of the pocket 35 radially outward.

To disassemble the bearing 10, first remove the lock screw 33, then remove the outer race 31 as shown in FIG. 6, and then hold the ball 33 with respect to the inner race 30 as shown in FIG. The container 34 is relatively moved in the axial direction. At this time, each ball 33 is pushed by the outer peripheral surface of the inner ring 30 and moves radially outward, but the claw 34 prevents the ball 33 from falling out of the pocket 35 radially outward. And
As shown in FIG. 8, when the retainer 34 is completely removed from the inner ring 30, the ball 33 is placed in the pocket 3 of the retainer 34.
5 is allowed to escape radially inward, so that the annular retainer 34 escapes without being dispersed radially outward.

To assemble the bearing 10, the retainer 34 is fitted to the inner ring 30, and then the ball 33 is pushed into the pocket 35 from the outside in the radial direction. At this time, the ball 33 is inserted into the pocket 35 by the elastic deformation of the claw 35. The ball 33 inserted inside the pocket 35
Is prevented by the claw 36 from going outward in the radial direction. This prevents the balls 33 from being dispersed radially outward and falling off when the bearing 10 is assembled. When all the balls 33 have been inserted into the pockets 35, the outer ring 31 is fitted and then fixed by the lock screw 13.

[0023]

According to the ball screw type steering apparatus according to the present invention, the ball of the four-point contact type ball bearing supporting the ball screw does not fall out of the pocket of the retainer at the time of assembly, and is disassembled. In this case, the disassembly and the assembling work can be easily and quickly performed because the disassembly and the disassembly work can be easily and quickly performed because the disassembly does not disperse outward in the radial direction and collectively escapes from the inside of the annular retainer. Further, the balls do not enter between the sector gear and the rack.

[Brief description of the drawings]

FIG. 1 is a sectional view of a ball screw type steering device according to an embodiment of the present invention.

FIG. 2 is a plan sectional view of a part of the ball bearing according to the embodiment of the present invention.

FIG. 3 is an expanded view of a part of a ball bearing retainer according to the embodiment of the present invention.

FIG. 4 is a cross-sectional view of a part of the ball bearing according to the embodiment of the present invention.

FIG. 5 is a configuration explanatory view of a ball bearing according to an embodiment of the present invention.

FIG. 6 is a configuration explanatory view of a ball bearing according to an embodiment of the present invention.

FIG. 7 is an explanatory view of the ball bearing according to the embodiment of the present invention when disassembled.

FIG. 8 is a configuration explanatory view of a retainer and a ball according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 4 ball screw 8 housing 10 four-point contact ball bearing 11 ball nut 12 rack 13 sector gear 14 output shaft 30 inner ring 33 ball 34 retainer 35 pocket 36 pawl

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 64-55170 (JP, U) JP-A 1-94616 (JP, U) JP-B-49-34843 (JP, B1) (58) Field (Int.Cl. ⁷ , DB name) B62D 3/08 F16C 33/38-33/44 B62D 5/24

Claims (1)

(57) [Claims] 1. A ball screw supported on a housing via a four-point contact ball bearing, a ball nut fitted to the ball screw, a sector gear meshing with a rack formed on the ball nut, and the sector gear An inner shaft of the bearing is integrally formed with a ball screw, and a ball of the bearing is formed so as to penetrate the annular retainer in a radial direction. In the ball screw type steering device inserted into the pocket, the retainer prevents the ball from coming out of the pocket in the radial direction and allows the ball to come out in the radial direction. Claw that protrudes toward the outside of the pocket to allow the ball to be pushed into the pocket from the outside in the radial direction. It is elastically deformable, and the protrusion of the claw radially outward from the outer peripheral surface of the cage can prevent the ball from coming out of the pocket radially outward when the cage is pulled out from the inner ring in the axial direction. Dimensions for the inner ring
When the cage is pulled out in the axial direction, it is retained in the pocket.
A ball screw type steering device characterized in that a dropped ball escapes radially inward .