JP2008087588A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of preventing any wear of corners at upper and lower ends of right and left side faces of a tilt-sliding column even when a large torsional force is applied to the column, and enhancing the durability of a tilt-sliding part thereby. <P>SOLUTION: When a steering wheel 103 is steered, an electric motor 72 of a steering assist unit 37 is driven, the required steering auxiliary torque is applied to an output shaft 374, and the force for twisting the entire lower column 3 by the reaction force transmitted from a wheel to the lower column 3 is added thereto. An arc-shaped chamfered part 35 in which an outer side in the radial direction is projecting with respect to the center axis of the lower column 3 is formed on upper and lower end corners of a left face 33 and a right face 34 of the lower column 3, and the lower column 3 is smoothly rotated. Thus, any large load is not applied to the upper and lower end corners of the left face 33 or the upper and lower end corners of the right face 34, the upper and lower end corners are not worn, any increase of the resistance of the tilt-sliding part is suppressed, and the durability of the tilt-sliding part is enhanced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steering apparatus, and more particularly to a tilt position adjustable electric steering apparatus that can adjust a tilt position of a steering wheel using an electric actuator as a power source in accordance with the physique and driving posture of a driver.

  As a device for adjusting the vertical position of the steering wheel in accordance with the physique and driving posture of the driver, there is an electric steering device called a tilt type steering device. There is an electric steering device called a tilt / telescopic steering device as a device for adjusting both the vertical position and the front / rear position of the steering wheel.

  In such an electric steering device, in order to ensure the rigidity of the steering device and to smoothly adjust the tilt position, there is no play in the gap of the tilt sliding portion between the column and the vehicle body mounting bracket.

  The electric steering device of Patent Document 1 is an electric steering device that can adjust the gap of the tilt sliding portion between the column and the vehicle body mounting bracket. In the electric steering device shown in Patent Document 1, a spacer is inserted into a gap between the column and the vehicle body mounting bracket, and the spacer is pressed against the column with an adjusting screw, thereby eliminating the gap in the tilt sliding portion.

  Moreover, in order to reduce the force with which the driver operates the steering wheel, an electric power steering device (steering force assist device) is often provided. When this electric power steering device is added to the electric steering device as shown in Patent Document 1, especially in a car having a large body weight, the auxiliary torque of the electric power steering device is large, so that the reaction force transmitted from the wheel to the column is large. A force that twists the entire column is added.

  In the conventional electric steering device as shown in Patent Document 1, there is no clamping device for clamping the tilt sliding portion between the column and the vehicle body mounting bracket. Therefore, if a force that twists the entire column is applied, the upper and lower corners of the left and right side surfaces of the sliding column are worn under a large load, and the worn metal powder damages the tilting sliding part. The tilt sliding resistance may increase or the durability of the tilt sliding portion may be reduced.

JP 2002-2503 A

  The present invention provides an electric steering device that improves the durability of the tilt sliding portion without causing wear on the upper and lower corners of the left and right side surfaces of the column that slides even when a large torsional force is applied to the column. The task is to do.

  The above problem is solved by the following means. In other words, the first invention is sandwiched between the steering shaft on which the steering wheel is mounted on the rear side of the vehicle body and the left and right side plates of the vehicle body mounting bracket which can be attached to the vehicle body so as to be slidable and rotatable. A column and tilt that can be tilted and adjusted with the tilt center axis as a fulcrum, or tilt position adjustment with the tilt center axis as a fulcrum, and telescopic position adjustment along the center axis of the steering shaft. Motor, a tilt drive mechanism for adjusting the tilt position of the column by the drive force of the tilt motor, left and right side surfaces formed on the column and sandwiched between the left and right side plates of the vehicle body mounting bracket so as to be tilted and slidable, Formed on the left and right sides of the column and radially outward with respect to the center axis of the column There is an electric steering apparatus comprising the arc-shaped surface of the convex.

  A second aspect of the invention is the electric steering apparatus according to the first aspect of the invention, wherein the left and right side surfaces of the column are formed flat, and the upper and lower corners of the left and right side surfaces of the column are at the center axis of the column. On the other hand, the electric steering device is characterized in that an arc-shaped chamfered portion having a convex outer side in the radial direction is formed.

  According to a third aspect of the present invention, in the electric steering device of the first aspect, the left and right side surfaces of the column are formed in a circular arc shape whose outer side in the radial direction is convex with respect to the central axis of the column. This is an electric steering device.

  A fourth invention is the electric steering device according to the first invention, wherein the left and right side surfaces of the column are a part of the outer periphery of the column formed in a cylindrical shape. .

  According to a fifth aspect of the present invention, in the electric steering apparatus according to the first aspect of the present invention, the electric steering system includes an electric assist mechanism that detects a torque acting on the steering shaft and applies a required steering assist force. Device.

  In the electric steering device of the present invention, the left and right side surfaces of the column sandwiched between the left and right side plates of the vehicle body mounting bracket so as to be slidable are provided with arcuate surfaces that are convex radially outward with respect to the central axis of the column. Yes. Therefore, even if a large torsional force is applied to the column, the column rotates smoothly, and a large load does not act on the upper and lower corners of the left and right side surfaces of the column. And the corner | angular part of a lower end does not wear and the durability of a tilt sliding part improves.

  In the following embodiments, an example in which the present invention is applied to a tilt / telescopic electric steering apparatus that adjusts both the vertical position and the front / rear position of the steering wheel will be described.

  FIG. 1 is an overall perspective view showing a state where an electric steering device 101 of the present invention is attached to a vehicle. The electric steering device 101 supports a steering shaft 102 so as to be rotatable. A steering wheel 103 is attached to the upper end (rear side of the vehicle body) of the steering shaft 102, and an intermediate shaft 105 is connected to the lower end of the steering shaft 102 (front side of the vehicle body) via a universal joint 104.

  A universal joint 106 is connected to the lower end of the intermediate shaft 105, and a steering gear 107 including a rack and pinion mechanism is connected to the universal joint 106.

  When the driver rotates the steering wheel 103, the rotational force is transmitted to the steering gear 107 through the steering shaft 102, the universal joint 104, the intermediate shaft 105, and the universal joint 106, and the tie rod is transmitted through the rack and pinion mechanism. 108 can be moved to change the steering angle of the wheel.

  FIG. 2 is a front view showing a main part of the electric steering apparatus 101 according to the first embodiment of the present invention. 3 is a view taken in the direction of arrow P in FIG. FIG. 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB of FIG. 2 and shows a tilt sliding portion between the vehicle body mounting upper bracket and the column according to the first embodiment of the present invention.

  As shown in FIGS. 2 to 5, the electric steering apparatus 101 according to the first embodiment of the present invention includes a vehicle body mounting upper bracket 2, a lower column (outer column) 3, a steering assist portion 37 (electric assist mechanism), an upper column ( Inner column) 4 and the like.

  The upper plate 21 of the vehicle body mounting upper bracket 2 on the rear side of the vehicle body is fixed to the vehicle body 11. The right end of the housing 371 of the steering assist unit (electric assist mechanism) 37 is fixed to the front side (left side) of the lower column 3 by press-fitting. The steering assist unit 37 includes an electric motor 372, a reduction gear box unit 373, an output shaft 374, and the like. The steering assisting portion 37 is supported by the lower body mounting bracket 375 on the vehicle body 11 via the tilt center shaft 376 so that the tilt position can be adjusted (swing in a plane parallel to the paper surface of FIG. 2).

  The upper column 4 is fitted to the inner periphery of the lower column 3 so as to be capable of telescopic position adjustment (sliding parallel to the central axis of the lower column 3). An upper steering shaft 102A is pivotally supported on the upper column 4, and a steering wheel 103 (see FIG. 1) is fixed to a rear side (right side in FIG. 2) end of the upper steering shaft 102A. Yes.

  A lower steering shaft (not shown) is rotatably supported on the lower column 3, and the lower steering shaft is splined to the upper steering shaft 102A. Therefore, regardless of the telescopic position of the upper column 4, the rotation of the upper steering shaft 102A is transmitted to the lower steering shaft.

  The steering assist unit 37 detects torque acting on the lower steering shaft, drives the electric motor 372, rotates the output shaft 374 with a required steering assist force, and moves an intermediate shaft (not shown) connected to the front side of the vehicle body. Via, it is connected to the steering gear, and the steering angle of the wheel can be changed.

  A left side plate 22 and a right side plate 23 extending in parallel downward from the upper plate 21 are formed on the upper plate 21 of the vehicle body mounting upper bracket 2. The left side surface 33 and the right side surface 34 of the lower column 3 are sandwiched between the inner side surfaces 221 and 231 of the left side plate 22 and the right side plate 23 so as to be slidable. That is, the right side surface 34 of the lower column 3 is in direct contact with the inner side surface 231 of the right side plate 23 of the vehicle body mounting upper bracket 2. The left side surface 33 and the right side surface 34 of the lower column 3 are formed in a plane.

  The lower ends of the left side plate 22 and the right side plate 23 are connected by a lower plate 24 to form a closed rectangular shape by the upper plate 21, the left side plate 22, the right side plate 23, and the lower plate 24, and the rigidity of the vehicle body mounting upper bracket 2 is determined. Has improved.

  A telescopic drive mechanism 5 for adjusting the telescopic position is attached to the outer periphery of the lower column 3. A tilt drive mechanism 6 for adjusting the tilt position is attached below the left side plate 22 and the right side plate 23 of the vehicle body mounting upper bracket 2.

  A worm 62 (see FIG. 4) attached to the output shaft of the tilt motor 61 for the tilt drive mechanism 6 meshes with a worm wheel 64 attached below the feed screw shaft 63 to rotate the tilt motor 61. This is transmitted to the feed screw shaft 63.

  The feed screw shaft 63 extends perpendicularly to the central axis of the tilt motor 61 (the vertical direction in FIGS. 2 to 4), and its upper and lower ends are rotatable to the vehicle body mounting upper bracket 2 by bearings 631 and 632. It is pivotally supported. A feed nut 65 is screwed onto a male screw formed on the outer periphery of the feed screw shaft 63.

  A nut holder 652 is slidably fitted on the feed nut 65 in a direction perpendicular to the plane of FIG. 4, and a tilt driving force transmission protrusion 651 is integrally formed on the nut holder 652. The tilt driving force transmission protrusion 651 protrudes toward the central axis of the lower column 3, and the tip of the tilt driving force transmission protrusion 651 is fitted in the engagement hole 66 formed in the lower column 3.

  Therefore, it is possible to absorb a positional shift between the circular motion of the lower column 3 and the linear motion of the feed nut 65 when adjusting the tilt position. When the feed screw shaft 63 rotates, the feed nut 65 and the tilt driving force transmission protrusion 651 linearly move in the vertical direction, and the lower column 3 swings along an arcuate locus with the tilt center shaft 376 as a fulcrum ( 2) in a plane parallel to the paper surface of FIG.

  A telescopic motor 51 is attached to the outer periphery of the lower surface of the lower column 3. A feed screw shaft 52 is fixed to the outer periphery of the lower surface of the lower column 3 in parallel with the central axis of the lower column 3, and the rear end (right end in FIG. 2) of the feed screw shaft 52 is connected to the rear end of the upper column 4. It is connected to the lower end of the fixed flange 41.

  The rotation of a worm attached to an output shaft (not shown) of the telescopic motor 51 is transmitted to a worm wheel (not shown), and a feed nut (not shown) screwed to the feed screw shaft 52 is rotated. By rotating the feed nut, the feed screw shaft 52 is reciprocated (moved in the left-right direction in FIG. 2), and the telescopic position of the upper column 4 is adjusted.

  As shown in FIGS. 3 and 5, the spacer 7 is interposed between the left side surface 33 of the lower column 3 and the inner side surface 221 of the left side plate 22 of the vehicle body mounting upper bracket 2. That is, the inner side surface 74 of the spacer 7 is in contact with the left side surface 33 of the lower column 3. Further, as shown in FIG. 2, the flat spacer 7 is formed in a rectangular shape.

  Two female screws 25, 25 are formed on the left side plate 22 of the vehicle body mounting upper bracket 2 so as to be spaced apart from each other in the vertical direction (tilt position adjusting direction) in FIGS. 2, 3, and 5. The female screws 25, 25 are It penetrates the left side plate 22. Male screws 81, 81 of the adjusting screws 8, 8 are screwed into the female screws 25, 25. Shaft portions 82 and 82 having a diameter smaller than the outer diameter of the male screws 81 and 81 are formed at the right ends of the adjusting screws 8 and 8.

  The spacer 7 is formed with two through holes 72, 72 at the same interval as the vertical interval of the female screws 25, 25. The inner diameter of the through holes 72, 72 is larger than the outer diameter of the shaft portions 82, 82. It is formed slightly larger. Therefore, when the shaft portions 82 and 82 and the through holes 72 and 72 are in phase with each other, if the male screws 81 and 81 of the adjusting screws 8 and 8 are screwed in, the shaft portions 82 and 82 are fitted into the through holes 72 and 72.

  If the male screws 81, 81 of the adjusting screws 8, 8 are further screwed in, the stepped surfaces of the male screws 81, 81 and the shaft portions 82, 82 abut against the outer surface 73 of the spacer 7, and the spacer 7 is moved to the left side of the lower column 3. It can be pressed towards the surface 33. As a result, even if the distance between the inner side surface 221 of the vehicle body mounting upper bracket 2 and the left side surface 33 of the lower column 3 is inclined due to a manufacturing error or the like, the screwing amounts of the male screws 81 and 81 of the adjusting screws 8 and 8 are increased. Is adjusted appropriately, the inner side surface 74 of the spacer 7 can be brought into contact with the left side surface 33 of the lower column 3 evenly.

  As a result, the spacer 7 is held at predetermined positions on the inner side surface 221 of the vehicle body mounting upper bracket 2 and the left side surface 33 of the lower column 3. When the adjustment of the adjustment screws 8 and 8 is completed, the lock nuts 83 and 83 are screwed into the male screws 81 and 81 to prevent the adjustment screws 8 and 8 from coming loose.

  In the first embodiment, the left side surface 33 of the lower column 3 and the inner side surface 74 of the spacer 7, and the right side surface 34 of the lower column 3 and the inner side surface 231 of the right side plate 23 of the vehicle body mounting upper bracket 2 are tilted relative to each other. A possible tilt sliding part is formed.

  Therefore, the tilt sliding resistance between the lower column 3 and the right side plate 23 and between the lower column 3 and the spacer 7 can be set to a desired sliding resistance, and the tilt sliding during the tilting operation is performed regardless of the tilt angle. The dynamic resistance is kept constant.

  In Embodiment 1 of the present invention, as shown in FIG. 5, arc-shaped chamfers 35 are formed at the upper and lower corners of the left side surface 33 of the lower column 3 and at the upper and lower corners of the right side surface 34. Is formed. The arc-shaped chamfered portion 35 extends in a direction orthogonal to the paper surface of FIG. 5, and is a tilt sliding portion between the inner side surface 74 of the spacer 7 and the inner side surface 231 of the right side plate 23 of the vehicle body mounting upper bracket 2. Is formed over the entire length.

  When the steering wheel 103 is steered by the electric steering device 101, the electric motor 372 of the steering assist unit 37 is driven, and a required steering assist torque acts on the output shaft 374 to change the steering angle of the wheel. Then, the reaction force transmitted from the wheel to the lower column 3 adds a force that twists the entire lower column 3, and the lower column 3 rotates about the central axis of the lower column 3.

  As described above, the upper end and lower end corners of the left side surface 33 of the lower column 3 and the upper end and lower end corners of the right side surface 34 are circles convex outward in the radial direction with respect to the central axis of the lower column 3. Since the arc-shaped chamfered portion 35 is formed, the lower column 3 rotates smoothly. Therefore, since a large load does not act on the upper and lower corners of the left side 33 of the lower column 3 and the upper and lower corners of the right side 34, the upper and lower corners are not worn, and the tilt sliding portion The increase in resistance is suppressed, and the durability of the tilt sliding portion is improved.

  When the electric steering device 101 needs to adjust the tilt position of the steering wheel 103, the driver operates a switch (not shown) to rotate the tilt motor 61 in either the forward or reverse direction. Then, the feed screw shaft 63 is rotated by the rotation of the tilt motor 61, and the feed nut 65 performs linear motion.

  Then, the nut holder 652 fitted on the feed nut 65 performs linear motion. Since the tilt driving force transmission protrusion 651 formed integrally with the nut holder 652 engages with the engagement hole 66 of the lower column 3, the lower column 3 moves upward or downward with the tilt center shaft 32 as a fulcrum. Tilt to move.

  When the electric steering device 101 needs to adjust the telescopic position of the steering wheel 103, the driver operates a switch (not shown) to rotate the telescopic motor 51 in either the forward or reverse direction. Then, the rotation of the telescopic motor 51 causes the feed screw shaft 52 to move in parallel with the central axis of the lower column 3, whereby the upper column 4 performs telescopic movement.

  Next, a second embodiment of the present invention will be described. 6 is a cross-sectional view taken along the line BB of FIG. 2 and shows a tilt sliding portion between the vehicle body mounting upper bracket and the column according to the second embodiment of the present invention. In the following description, only structural parts different from the above-described embodiment will be described, and redundant description will be omitted. Further, the same parts will be described with the same numbers.

  In the first embodiment, the left side surface 33 and the right side surface 34 of the lower column 3 are formed to be flat, but the second embodiment is an example in which the left side surface and the right side surface of the lower column 3 are formed in an arc shape.

  As shown in FIG. 6, in the second embodiment of the present invention, the left side surface 331 and the right side surface 341 of the lower column 3 are formed in a circular arc shape whose outer side in the radial direction is convex with respect to the central axis of the lower column 3. . The arc-shaped left side surface 331 and right side surface 341 extend in a direction orthogonal to the paper surface of FIG. 6, and are between the inner side surface 74 of the spacer 7 and the inner side surface 231 of the right side plate 23 of the vehicle body mounting upper bracket 2. It is formed over the entire length of the tilt sliding part.

  When the steering wheel 103 is steered by the electric steering device 101, the electric motor 372 of the steering assist unit 37 is driven, and a required steering assist torque acts on the output shaft 374 to change the steering angle of the wheel. Then, the reaction force transmitted from the wheel to the lower column 3 adds a force that twists the entire lower column 3, and the lower column 3 rotates about the central axis of the lower column 3.

  As described above, since the left side surface 331 and the right side surface 341 of the lower column 3 are formed in an arc shape, the lower column 3 rotates smoothly. Accordingly, since a large load does not act on the upper and lower corners of the left side 331 and the right side 341 of the lower column 3, the upper and lower corners are not worn, and an increase in the resistance of the tilt sliding portion is suppressed. In addition, the durability of the tilt sliding portion is improved.

  Next, a third embodiment of the present invention will be described. FIG. 7 is a cross-sectional view taken along the line BB of FIG. 2 and shows a tilt sliding portion between the vehicle body mounting upper bracket and the column according to the third embodiment of the present invention. In the following description, only structural parts different from the above-described embodiment will be described, and redundant description will be omitted. Further, the same parts will be described with the same numbers.

  In the first embodiment, the left side surface 33 and the right side surface 34 of the lower column 3 are formed flat, but the third embodiment is an example in which the entire outer periphery of the lower column 3 is cylindrical.

  As shown in FIG. 7, in the third embodiment of the present invention, the entire outer periphery 31 of the lower column 3 is formed in a cylindrical shape. The cylindrical outer periphery 31 extends in a direction orthogonal to the paper surface of FIG. 7, and is a tilt sliding portion between the inner surface 74 of the spacer 7 and the inner surface 231 of the right side plate 23 of the vehicle body mounting upper bracket 2. It is formed over the entire length. In the third embodiment, the outer periphery 31 of the lower column 3 and the inner side surface 74 of the spacer 7, and the outer periphery 31 of the lower column 3 and the inner side surface 231 of the right side plate 23 of the vehicle body mounting upper bracket 2 can be slid relative to each other. It constitutes a tilt sliding part.

  When the steering wheel 103 is steered by the electric steering device 101, the electric motor 372 of the steering assist unit 37 is driven, and a required steering assist torque acts on the output shaft 374 to change the steering angle of the wheel. Then, the reaction force transmitted from the wheel to the lower column 3 adds a force that twists the entire lower column 3, and the lower column 3 rotates about the central axis of the lower column 3.

  As described above, since the outer periphery 31 of the lower column 3 is formed in a cylindrical shape, the lower column 3 rotates smoothly. Accordingly, since a large load does not act on the outer periphery 31 of the lower column 3, the outer periphery 31 of the lower column 3 is not worn, and an increase in resistance of the tilt sliding portion is suppressed, and the durability of the tilt sliding portion is improved. To do.

  In the above embodiment, the lower column 3 is an outer column and the upper column 4 is an inner column, but the lower column 3 may be an inner column and the upper column 4 may be an outer column.

  In the embodiments of the present invention, the case where the present invention is applied to a tilt / telescopic type electric steering apparatus capable of both tilt position adjustment and telescopic position adjustment has been described. The present invention may be applied to the electric steering apparatus.

It is a whole perspective view which shows the state which attached the electric steering device 101 of this invention to the vehicle. It is a front view which shows the principal part of the electric steering apparatus 101 of Example 1 of this invention. FIG. 3 is a view taken in the direction of arrow P in FIG. FIG. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a cross-sectional view taken along the line B-B of FIG. 2, showing a tilt sliding portion between the vehicle body mounting upper bracket and the column according to the first embodiment of the present invention. 2 is a cross-sectional view taken along the line B-B of FIG. 2, and shows a tilt sliding portion between a vehicle body mounting upper bracket and a column according to Embodiment 2 of the present invention. 2 is a cross-sectional view taken along the line BB of FIG. 2 and shows a tilt sliding portion between a vehicle body mounting upper bracket and a column according to Embodiment 3 of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Electric steering device 102 Steering shaft 102A Upper steering shaft 103 Steering wheel 104 Universal joint 105 Intermediate shaft 106 Universal joint 107 Steering gear 108 Tie rod 11 Car body 2 Car body mounting upper bracket 21 Upper plate 22 Left plate 221 Inner side surface 23 Right side plate 231 Inner side surface 24 Lower plate 25 Female thread 3 Lower column 31 Outer circumference 33 Left side 331 Left side 34 Right side 341 Right side 35 Arc-shaped chamfer 37 Steering assist (electric assist mechanism)
371 Housing 372 Electric motor 373 Reduction gear box 374 Output shaft 375 Lower body mounting bracket 376 Tilt center shaft 4 Upper column 41 Flange 5 Telescopic drive mechanism 51 Telescopic motor 52 Feed screw shaft 6 Tilt drive mechanism 61 Tilt motor 62 Worm 63 Feed screw shaft 631, 632 Bearing 64 Worm wheel 65 Feed nut 651 Tilt driving force transmission protrusion 652 Nut holder 66 Engagement hole 7 Spacer 72 Through hole 73 Outer side surface 74 Inner side surface 8 Adjustment screw 81 Male screw 82 Shaft portion 83 Lock nut

Claims (5)

A steering shaft with a steering wheel mounted on the rear side of the vehicle body,
Tilt is slidably held between the left and right side plates of the body mounting bracket that can be mounted on the body, and the steering shaft is pivotally supported, and the tilt position is adjusted with the tilt center axis as a fulcrum, or the tilt center axis is A column capable of both tilt position adjustment as a fulcrum and telescopic position adjustment along the central axis of the steering shaft,
Tilt motor,
A tilt drive mechanism for adjusting the tilt position of the column by the drive force of the tilt motor;
Left and right side surfaces formed on the column and sandwiched between the left and right side plates of the vehicle body mounting bracket so as to be tilted and slidable,
An electric steering apparatus comprising arcuate surfaces formed on left and right side surfaces of the column and having a convex outer side in the radial direction with respect to a central axis of the column. In the electric steering device according to claim 1,
The left and right sides of the column are formed in a plane,
An electric steering apparatus characterized in that arcuate chamfered portions that are convex outward in the radial direction with respect to the central axis of the column are formed at the upper and lower corners of the left and right side surfaces of the column. In the electric steering device according to claim 1,
The left and right sides of the column
An electric steering device characterized in that the outer side in the radial direction with respect to the central axis of the column is formed in a circular arc shape. In the electric steering device according to claim 1,
The left and right sides of the column
An electric steering apparatus comprising a part of an outer periphery of a column formed in a cylindrical shape. In the electric steering device according to claim 1,
An electric steering apparatus comprising an electric assist mechanism for detecting a torque acting on the steering shaft and applying a required steering assist force.

Images