JP2004210064A - Vehicle steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle steering system capable of accurate formation of a holding portion for holding a transmission bearing with a rotating cylinder without requiring much man-hour, mass-production, and reliable transmission from a rotary drive source for steering to a steering shaft. <P>SOLUTION: When transmission bearings R<SB>1</SB>to R<SB>4</SB>having an inner ring inclined at a given angle within the width of an outer ring are held by holding portions 21 to 24 formed in the axial cross-section of the rotation cylinder 2, the inner ring is engaged with thread groove 10 formed on the outer surface of a steering shaft 1, thereby facilitating the formation of the holding portions 21 to 24. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vehicle steering apparatus having a steering shaft that moves in an axial direction in response to operation of a steering member such as a steering wheel, and transmitting the movement of the steering shaft to a steering wheel to perform steering. About.
[0002]
[Prior art]
In steering of a vehicle, an operation of a steering member (generally, a rotation operation of a steering wheel) performed by a driver is transmitted to a steering shaft in a steering mechanism, and a steering wheel is moved by moving the steering shaft in an axial direction. (Generally, the left and right front wheels) are steered.
[0003]
In recent years, as such a vehicle steering system, a steering assist motor (rotation drive source) attached to a part of a steering mechanism is driven in accordance with an operation of a steering member by a driver, and a rotational force of the motor is used. The electric power steering device which assists the steering by transmitting the information to the steering shaft has been widely put into practical use. Further, a steering mechanism mechanically separated from the steering member is provided, and a steering motor (rotational drive source) is attached to a part of the steering mechanism, and a detection result of an operation direction and an operation amount of the steering member is provided. Further, the motor is driven based on a detection result of a traveling state such as a vehicle speed, turning, presence or absence of acceleration and deceleration, and the torque of the motor is transmitted to a steering shaft. 2. Description of the Related Art A separation-type steering device configured to operate a steering mechanism, that is, a so-called steer-by-wire steering device is being developed.
[0004]
2. Description of the Related Art In a vehicle steering apparatus of this type, a motion conversion apparatus for converting a rotational motion of a steering assisting or steering motor into a linear motion and transmitting the linear motion to a steering shaft is used. This motion conversion device is required to have a compact configuration and high transmission efficiency so that it can be disposed in a limited space around the steering mechanism, including a motor serving as a rotational drive source. I have.
[0005]
As one of the motion converting devices having a simple configuration capable of meeting such a demand, there is a motion converting device using a feed bearing (for example, see Patent Document 1). FIG. 5 is a longitudinal sectional view showing a main part of a vehicle steering system provided with the motion conversion device. The steering shaft 1 has a screw groove 10 having a semicircular cross section formed on an outer peripheral surface thereof. a rotary cylinder 2 which is rotatably supported in coaxially (in FIG. 4) a plurality which is internally fitted held on the rotary cylinder 2 is constituted by a feed bearing R _a to R _d of .
[0006]
The rotary cylinder 2 is rotatably supported inside a cylindrical housing H by a ball bearing B integrally formed with an intermediate portion thereof as an inner ring, and is coaxial with the steering shaft 1 by transmission from a motor (not shown). To rotate. Feed bearing R _a to R _d of the inner rotating cylinder 2 retains a plurality of balls between the outer ring and the inner ring, with the ball bearing having a sufficiently large inner diameter than the insertion has an outer diameter of the steering shaft 1 inside In addition, each of the other holding portions 2 a to 2 d arranged in parallel in the axial direction inside the rotary cylinder 2 is eccentrically held at an inclination angle substantially equal to the lead angle of the thread groove 10.
[0007]
The inner peripheral surface of the inner ring of the feed bearing R _a to R _d, semicircular protrusions are circumferentially provided corresponding to the cross section of the thread groove 10, the feed bearing R _a to R _d are each eccentric At the circumferential position close to the steering shaft 1, and is engaged with the thread groove 10 via the projection. The engagement positions of the feed bearings R _a and R _d on both sides indicated by white circles in the figure are set on the front side of the figure, and the engagement positions of the center feed bearings R _b and R _c indicated by black circles in the figure. It is set on the back side of the figure, further, distributing the engagement position of the respective both sides of the axis, so as to restrain the radial movement of the steering shaft 1 by four feed bearing R _a to R _d It is.
[0008]
The vehicular steering device constructed as above, when the rotating cylinder 2 through the transmission from the motor to rotate around the axis, four feed bearing R _a to R inner screw groove of _d held on the rotary cylinder 2 rolls while maintaining the engagement with 10, the steering shaft 1, axial component force acting force to the engagement position of the feed bearing R _a to R _d each applied along the inclination of the thread groove 10 is applied As a result, the steering shaft 1 moves in the axial direction by the action of the component force, and the above-described steering is assisted.
[0009]
[Patent Document 1]
JP 2001-315655 A
[Problems to be solved by the invention]
FIG. 6 is an explanatory diagram of a state in which the feed bearing _Ra is held on the rotary cylinder 2. As shown, the holding portion 2a for holding the feed bearing R _a forms a recess semicircular cross section corresponding to the outer shape of the feed bearing R _a on the inside of the rotating cylinder 2, the open side of the recess extend in a tangential direction, and is constituted by allowed opening the insertion opening of rectangular cross-section corresponding to the longitudinal section of the bearing R _a feed on the outer peripheral surface of the rotating cylinder 2.
[0011]
Retention of such feed bearing R _a on the holding portion 2a, the said transmission Ri bearing R _a, as shown by arrow in FIG. 6, pushed into the holding portion 2a through the rotating cylinder 2 periphery of the insertion opening, the holding It is made to abut against a semicircular recess forming the bottom of the portion 2a. Note (see FIG. 5) holding portion 2b~2d of the other three feed bearing _R b to R _d are also configured in the same manner as the holding portion 2a.
[0012]
FIG. 7 is an explanatory diagram of a procedure for forming the holding section 2a as described above. As shown in FIG. 7A, the holding portion 2a having the above-described form first forms a hollow portion 2f having a circular cross section eccentric to one side inside the rotary cylinder 2, and then shown in FIG. 7B. By removing the region 2g sandwiched between the two tangents extending to the eccentric side of the cavity 2f to the outer peripheral surface of the rotary cylinder 2, the half of the cavity 2f is removed as shown in FIG. part is leaving implemented as a semi-circular recess for supporting the bearing R _a send.
[0013]
Now, in the procedure for forming the holding portion 2a as described above, the hollow portion 2f is formed by, for example, boring from the end face of the rotary cylinder 2, and the removal of the region 2g continuous with the hollow portion 2f is performed, for example, This is realized by electric discharge machining from the outside of the rotary cylinder 2. However, since the holding portion 2a is inclined at a predetermined angle with respect to the axis of the rotating cylinder 2, in the above-described forming procedure, particularly, the hollow portion 2f formed inside the rotating cylinder 2 and the rotating cylinder 2 There is a problem that it is difficult to align with the region 2g to be removed from the outside, it takes a lot of man-hours to process the holding portion 2a, and it is inevitable that defective products are generated, resulting in deterioration of product yield. This is a factor that makes mass production difficult.
[0014]
The present invention has been made in view of such circumstances, and by improving a feed bearing held in a rotating cylinder, it is possible to form a holding portion for holding the feed bearing with high accuracy without requiring a large number of steps. It is an object of the present invention to provide a vehicle steering apparatus which is excellent in mass productivity and can reliably transmit power from a steering rotary drive source to a steering shaft.
[0015]
[Means for Solving the Problems]
A steering apparatus for a vehicle according to a first aspect of the present invention includes a steering shaft supported movably in an axial direction and having a thread groove formed on an outer peripheral surface, and rotatably supported coaxially with the steering shaft. The rotating cylinder and a plurality of holding portions eccentrically held in each of a plurality of holding portions arranged in parallel in the axial direction inside the rotating cylinder, and a portion of an inner peripheral surface is engaged with the screw groove. A feed bearing, and converting the rotation of the rotary cylinder by transmission from a rotational drive source for steering into a movement in the axial direction of the steering shaft by rolling of the feed bearing guided by the screw groove. In the steering apparatus for a vehicle that performs steering, the feed bearing is inclined with an outer ring fitted and held in the holding portion and an angle substantially equal to a lead angle of the thread groove within a width of the outer ring. The vehicle includes an inner ring, and a plurality of rolling elements interposed between the inner ring and the outer ring. And wherein the door.
[0016]
In the present invention, the feed bearing held inside the rotary cylinder includes an inner ring inclined at an angle corresponding to the lead angle of the thread groove within the width of the outer ring, and the feed bearing and the shaft are provided inside the rotary cylinder. When held by a holding portion formed in a plane perpendicular to the plane, the inner ring is inclined along the screw groove and engages with the screw groove as in the conventional case, and is transmitted by a rotation drive source for steering. The rotation of the rotating cylinder is converted into movement in the axial direction of the steering shaft to perform steering. Since the holding portion of the feed bearing is located in a plane orthogonal to the axis of the rotary cylinder, it can be formed with high accuracy without requiring a large number of steps.
[0017]
Further, a steering apparatus for a vehicle according to a second invention of the present invention is characterized in that the rotary cylinder according to the first invention is supported with a predetermined radial gap on one side in the axial direction.
[0018]
In the present invention, one side of the rotary cylinder is supported through a predetermined radial gap, the deflection of the steering shaft caused by the action of various external forces is allowed within the range of the radial gap, and rotation of the rotary cylinder is achieved. To the steering shaft smoothly.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments. FIG. 1 is a schematic diagram showing the overall configuration of a vehicle steering system according to the present invention, and illustrates a rack-and-pinion type steering mechanism that operates in accordance with a rotation operation of a steering wheel S as a steering member, and the steering mechanism. And a motor (rotary drive source) 3 for assisting steering provided to the vehicle.
[0020]
Steering mechanism includes a rack housing H ₁ lateral direction extending the cylindrical of the vehicle body, not shown, movably supported by the steering shaft in the interior of the rack housing H ₁ to axial direction (the rack shaft) 1 is provided. Both ends of the steering shaft 1 is projected on both sides of the rack housing H _1, are connected via the tie rods 13 and 13 each to the knuckle arms 12, 12 of the left and right front wheels 11 and 11 as the wheels for steering The knuckle arms 12, 12 are pushed and pulled via the tie rods 13 by the movement of the steering shaft 1 in both directions, so that the left and right front wheels 11, 11 are steered.
[0021]
On one side half portion of the rack housing H _1, to cross it and the shaft center and the pinion housing H ₂ is continuously provided, the inside of the pinion housing H _2, rotatably pinion shaft at axis 14 are supported. The pinion shaft 14, only the projecting portion of the upper pinion housing H ₂ is Yes illustrated, the projecting portion is connected to the column shaft 17 through the intermediate shaft 16 provided with universal joints 15, 15 at both ends .
[0022]
At the bottom of the pinion shaft 14 which extends inside the pinion housing H _2, a pinion (not shown) is provided integrally. The rack on the steering shaft 1 supported inside the housing H _1, and the rack teeth are formed over a suitable length, including the intersecting position between the pinion housing H _2, the rack teeth, the pinion shaft 14 It is engaged with the lower pinion.
[0023]
Column shaft 17 is rotatably supported in coaxially inside the column housing H ₃ having a cylindrical shape is fixedly supported inclined rearward and upward in the interior of the passenger compartment (not shown), a steering wheel S is is fitted fixed to the upper end of the column shaft 17 which projects at the top of the column housing H _3.
[0024]
With the above configuration, when the steering wheel S is rotated for steering, the column shaft 17 to which the steering wheel S is fitted and fixed rotates around the axis, and this rotation is performed via the intermediate shaft 16 and the pinion shaft. The rotation of the pinion shaft 14 is converted into a movement in the axial direction of the steering shaft 1 at the meshing portion of the pinion and the rack teeth, and the left and right front wheels 11, 11 are steered as described above.
[0025]
Motor 3 for steering assistance for assisting such a steering, the other side half portion of the rack housing H _1, mounted by crossing it the axis, the following as the rack housing H ₁ inside the steering shaft 1 Transmission is configured.
[0026]
Figure 2 is a longitudinal sectional view showing the internal configuration of the rack housing H ₁ of the mounting portion near the motor 3 for steering assist. Motor 3 as shown in the figure, is provided continuously to the rack housing H _1, the end of the cylindrical motor housing H ₄ projecting radially outward, via a shim 30 for adjusting the position of the axial direction are flange fixing Te to the distal end of the motor shaft 31 which projects into the interior of the rack housing H _1, the small bevel gear 32 is integrally formed.
[0027]
Inside the rack housing H _1, the rotary cylinder 2 so as to correspond to the mounting position of the above-described motor 3 are arranged. Rotating cylinder 2 is rotatable in the one side in the axial direction is supported by a pair of angular ball bearings 25 and 25, the rack housing H ₁ inside the steering shaft 1 coaxially with. Angular contact ball bearings 25, 25 are fitted in the rack housing H _1, is fixed by applying a predetermined preload by tightening the preload nut 26 from one side in the axial direction, the rotating cylinder 2 and the radial direction It is supported so that it cannot move in the thrust direction.
[0028]
Threaded portion of the preload nut 26 and the rack housing H ₁ is located a tapered thread whose diameter decreases toward the innermost side, so as to prevent destabilization of the supported state of the rotating cylinder 2 by loosening the preload nut 26 There is something. Loosening of the preload nut 26 is caused by the difference in thermal expansion coefficient due to external, the difference in the material of the rack housing H ₁ and preload nut 26 caused by vibration applied during driving of the vehicle. As described above, the loosening prevention by the tapered screw can be realized without adding a dedicated part, and the preload applied in the assembling stage can be maintained, and the rotating cylinder 2 can be reliably supported. .
[0029]
The rotating cylinder 2 supported in this manner has a large bevel gear 27 provided on the outer periphery of the middle part, and the large bevel gear 27 is a small bevel gear provided at the tip of the motor shaft 31 of the motor 3. 32. Here, the small bevel gear 32 is formed integrally with the motor shaft 31 of the steering assist motor 3 as described above, has high concentricity with the motor shaft 31, and meshes with the large bevel gear 27. , during assembly of the motor 3 to the motor housing H _4, it is better implemented by the thickness adjustment of the shim 30 interposed therebetween.
[0030]
With the above configuration, the rotation of the motor shaft 31 accompanying the driving of the steering assist motor 3 is transmitted to the rotary cylinder 2 via the small bevel gear 32 and the large bevel gear 27, and in accordance with this transmission, the rotary cylinder 2 , And rotates about an axis under the support of the angular ball bearings 25, 25.
[0031]
On the other hand, the other side of the rotating cylinder 2, a rack housing a predetermined radial gap in the support bush 28 of the fitting is an annular the inner surface of the H ₁ [delta] is opposed, within the scope of this radial gap [delta] It is supported to allow displacement. With such support, the rotating cylinder 2 can be displaced following the deflection of the steering shaft 1 during the rotation described above. The deflection of the steering shaft 1 is inevitably caused by external force such as a road surface reaction force applied to the left and right front wheels 10 and 10 connected to both ends and a meshing reaction force applied to the meshing portion between the pinion and the rack teeth. By the displacement of the rotary cylinder 2 following the deflection, the motion conversion described later can be performed with high efficiency.
[0032]
In FIG. 2, a radial gap δ is secured between the support bush 28 fitted in the rack housing H ₁ and the outer peripheral surface of the rotary cylinder 2. fitted around the annular support bush may be configured to secure the radial gap between the inner peripheral surface of the rack housing H _1, further, annular support bushing on both the rack housing H ₁ and rotating barrel 2 May be fitted to secure a radial gap between these support bushes. In Figure 2 also, there is shown an enlarged view of the radial gap δ between the rack housing H ₁ and the rotary cylinder 2, but a proper value of the radial gap δ is the order of 0.1 to 0.2 mm .
[0033]
Four feed bearings R _{1 to} R ₄ are internally fitted and held inside the rotating cylinder 2 supported as described above. A screw groove 10 having a semicircular cross-section is provided on the outer peripheral surface of the steering shaft 1 which is inserted coaxially inside the rotary cylinder 2, including a portion facing the inside of the rotary cylinder 2. It is formed over a length range corresponding to the stroke.
[0034]
FIG. 3 is a longitudinal sectional view of a feed bearing used in the vehicle steering system according to the present invention. Note that this figure is the feed bearing R ₁ is illustrated, other feed bearing R ₂ to R ₄ have the same configuration.
[0035]
Bearing R ₁ Feed As illustrated, the outer ring 40 and inner ring 41 forming together an annular, multiple engaging with both opposing peripheral surface formed rolling groove of ball (rolling elements) 42, 42 ... It is configured as a ball bearing that is assembled through the ball bearing. Here, the outer ring 40 is formed wider than the inner ring 41 located on the inner side, and the inner ring 41 is assembled by being inclined at a predetermined inclination angle θ within the width of the outer ring 40. This assembling can be realized by machining the rolling grooves of the balls 42 provided on the inner peripheral surface of the outer race 40 with the above-described inclination angle θ. Note that the inclination angle θ of the inner ring 41 is set to be substantially equal to the lead angle θ ₀ (see FIG. 2) of the thread groove 10 provided on the outer peripheral surface of the steering shaft 1.
[0036]
The inner ring 41 of the feed bearing R _{1 has} an inner diameter sufficiently larger than the outer diameter of the steering shaft 1, and the inner peripheral surface of the inner ring 41 has, as shown in FIG. An engagement protrusion 43 having a semicircular cross section corresponding to the provided screw groove 10 is provided around the periphery.
[0037]
Feed bearing R ₁ configured in this way, fit the outer ring 40 in the holding portion 21 provided on the inner side of the rotating cylinder 2, Yes eccentric is held with a predetermined eccentricity radially, steered by the eccentric At a position in the circumferential direction closest to the shaft 1, an engagement protrusion 43 provided around the inner race 41 is engaged with the thread groove 10 on the outer periphery of the steering shaft 1.
[0038]
This engagement position is made at a position where the inclination of the inner ring 41 provided with the engagement protrusion 43 matches the lead angle θ ₀ of the thread groove 10 as shown by a white circle in FIG. The inner race 41 of R ₁ is inclined with an inclination angle θ with respect to the outer race 40, and the inclination angle θ is set to be substantially equal to the lead angle θ _0, and is stored within the width of the outer race 40. Therefore, the holding portion 21 holding the outer ring 40 can be a circular hole eccentric by a predetermined length in a plane orthogonal to the axis of the rotating cylinder 2.
[0039]
Similarly, the feed bearings R ₂ , R ₃ , and R ₄ having the same configuration as the feed bearing R ₁ are provided on separate holding portions 22, 23, and 24 provided on one side of the holding portion 21 in the axial direction. The respective outer races 40 are held, and the engagement projections 43 provided on the inner race 42 are engaged with the screw grooves 10. These holding parts 22, 23, 24 are also in a plane perpendicular to the axis of the rotary cylinder 2. In this case, a circular hole having a predetermined length eccentricity can be obtained.
[0040]
The engagement positions of the two feed bearings R ₁ , R ₄ on both sides indicated by white circles in FIG. 2 are set on the front side of the figure, and the center two feed bearings R indicated by black circles in FIG. The engagement positions of R ₂ and R ₃ are set on the back side of the drawing, and the engagement positions on each side are distributed to both sides of the axis of the steering shaft 1. the ₁ to R ₄ are so as to restrain the radial movement of the steering shaft 1.
[0041]
The vehicular steering device constructed as described above, when the rotary cylinder 2 is rotated around the axis through the transmission from the motor 3 for steering assist, engaging the inner race screw groove 10 of the feed bearing R ₁ to R ₄ The steering shaft 1 rolls, and the steering shaft 1 is subjected to an axial component of the acting force applied to each of the feed bearings R _{1 to} R ₄ along the inclination of the screw groove 10. 1 moves in the axial direction, and the steering as described above is assisted in accordance with this movement.
[0042]
In order to perform the above steering assist with high efficiency, it is necessary that the thread groove 10 on the outer periphery of the steering shaft 1 and each of the feed bearings R _{1 to} R ₄ maintain a good engagement state. feed bearing R ₁ to R ₄ which is held by the holder 21 to 24 provided in the cylinder 2 is positioned with high accuracy, also the positioning needs to be implemented without requiring a great deal of man-hours.
[0043]
Figure 4 is an explanatory view of a holding state of the feed bearing R ₁ to the rotating cylinder 2. Holding unit 21 for holding the feed bearing R _1, as shown by the dashed line in the figure, to form a recess semicircular cross section corresponding to the outer shape of the feed bearing R ₁ in the interior of the rotating cylinder 2, the opening of the recess by extending the side in the tangential direction, and is constituted by allowed opening a rectangular insertion opening corresponding to the longitudinal section of the bearing R ₁ sends to the outer peripheral surface of the rotating cylinder 2. As shown by the arrow in FIG. 4, the feed bearing R ₁ , which is schematically indicated by a two-dot chain line, is pushed into the holding portion 21 through the insertion port on the outer periphery of the rotary cylinder 2, and is attached to the bottom of the holding portion 21. The inner peripheral surface of this abutting portion is engaged with the thread groove 10 on the outer periphery of the steering shaft 1 to form the structure as shown in FIG.
[0044]
As shown in FIG. 7, the holding portion 21 as described above is provided with a hollow portion 2f having a circular cross section eccentric to one side by boring inside the rotary cylinder 2, and then, outside the rotary cylinder 2. , A region 2g sandwiched between two tangents extending toward the eccentric side of the cavity 2f can be formed by a machining procedure similar to the conventional one.
[0045]
Here, the holding portion 21 of the feed bearing R ₁ is as described above, a circular hole having no inclined relative to a plane orthogonal to the axis of the rotary cylinder 2, boring for forming the cavity portion 2f Can be performed with high accuracy, and at the time of the subsequent removal of the region 2g, an accurate machining position can be determined from the outside of the rotary cylinder 2 and the inner cavity 2f of the rotary cylinder 2 can be accurately determined. 4g can be removed, and the holding portion 21 shown in FIG. 4 can be formed with high accuracy.
[0046]
Similarly, the holding parts 22 to 24 of the other feed bearings R _{2 to} R ₄ can be formed with high accuracy without requiring many man-hours, and the feed bearings R ₁ to R ₁ held by the holding parts 21 to 24 can be formed. the exact positioning of the R ₄ is possible, it is possible to perform steering assist by transmitting at a high efficiency from the motor 3 for steering assist.
[0047]
If the steering assist by transmitting from the motor 3, such as more was made, the rack housing H ₁ for supporting the steering shaft 1, the rotation moment about the axis is generated by the action of the rotation of the motor 3 reaction forces and rotational inertia. The rack housing H ₁ as shown in FIG. 1, in the vicinity of the crossover position of the pinion housing H _2, the fixed bracket 18 and 18 so as to project on both sides sandwiching the interior of the rack shaft 1 is provided with, these It is fixed to the vehicle body by fixing brackets 18,18. By this fixing, the influence of the rotational moment can be eliminated, and the above-described steering assist can be stably performed. Note that this support structure is also effective in a case where another motion conversion device such as a ball screw is provided to convert the rotational motion of the motor 3 into the movement of the steering shaft 1.
[0048]
In the above embodiment, a configuration including four feed bearings R _{1 to} R ₄ has been described, but a configuration including three or five or more feed bearings may be employed.
[0049]
Further, in the above embodiment, an example of application to an electric power steering device that transmits the rotation of a steering assist motor to a rack shaft as a steering shaft in a vehicle including a rack and pinion type steering mechanism has been described. The present invention is applicable to any type of electric power steering device having a steering shaft that moves in the axial direction for steering, and configured to transmit the rotation of a steering assist motor to the steering shaft, Furthermore, the present invention can be applied to a case where a rotary drive source other than the electric motor 3 is provided.
[0050]
In addition, the present invention is not limited to the power steering device, but includes a steering mechanism mechanically separated from the steering member, and a steering motor is attached to a part of the steering mechanism, and only the rotation of the motor is used. Also in a steer-by-wire type steering apparatus configured to perform steering, the present invention can be applied for transmission from the motor to a steering shaft, and the same effect can be obtained.
[0051]
【The invention's effect】
As described in detail above, in the vehicle steering system according to the present invention, the holding portion of the feed bearing, which is held by the rotating cylinder and engages with the thread groove on the outer periphery of the steering shaft, requires a large number of man-hours in the axial cross section of the rotating cylinder. The present invention has excellent effects such as being able to be formed with high accuracy without necessity and being able to mass-produce a reliable motion conversion from rotation of the rotary cylinder to movement of the steering shaft in the axial length direction. Play.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a vehicle steering system according to the present invention.
FIG. 2 is a longitudinal sectional view showing an internal configuration of a rack housing near a mounting portion of a steering assist motor.
FIG. 3 is a longitudinal sectional view of a feed bearing used in the vehicle steering system according to the present invention.
FIG. 4 is an explanatory diagram of a holding state of a feed bearing on a rotary cylinder.
FIG. 5 is a longitudinal sectional view showing a main part of a conventional vehicle steering system provided with a motion conversion device using a feed bearing.
FIG. 6 is an explanatory view of a state in which a feed bearing is held on a rotary cylinder in a conventional vehicle steering system.
FIG. 7 is an explanatory diagram of a procedure for forming a holding portion of the feed bearing.
[Explanation of symbols]
1 Steering shaft 2 Rotating cylinder 3 Motor (rotation drive source)
10 Screw groove 40 Outer ring 41 Inner ring 42 Ball (rolling element)
21 to 24 Holding parts R _{1 to} R ₄ Feed bearing δ Radial gap

Claims (2)

A steering shaft movably supported in the axial length direction and having a thread groove formed on an outer peripheral surface thereof; a rotating cylinder rotatably supported coaxially with the steering shaft; and a shaft length inside the rotating cylinder. A plurality of feed bearings, each of which is eccentrically held by a plurality of holding portions arranged side by side in the direction, and a portion of an inner peripheral surface is engaged with the screw groove, and a plurality of feed bearings are provided from a rotational drive source for steering. In the vehicle steering device, the rotation of the rotary cylinder due to transmission is converted into movement in the axial direction of the steering shaft by the rolling of the feed bearing with the screw groove serving as a guide, thereby performing steering.
The feed bearing, an outer ring fitted and held in the holding portion,
An inner ring inclined at an angle substantially equal to the lead angle of the screw groove within the width of the outer ring,
A vehicle steering system comprising a plurality of rolling elements interposed between the inner wheel and the outer wheel. The vehicle steering system according to claim 1, wherein the rotary cylinder is supported with a predetermined radial gap on one side in the axial direction.

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