JP5338844B2 - Electric steering device - Google Patents

Description

  The present invention relates to an electric steering device, and more particularly to an electric steering device capable of adjusting a tilt position or a telescopic position of a steering wheel by an electric motor.

  It is necessary to adjust the tilt position and telescopic position of the steering wheel according to the driver's physique and driving posture, and this tilt position or telescopic position can be adjusted easily using an electric motor. In many cases, a type steering device is employed. As such an electric steering apparatus, there is an electric steering apparatus disclosed in Patent Document 1.

  The electric steering device of Patent Document 1 is a cylinder having a spherical protrusion and a concave spherical surface with which the ball is fitted to the inner periphery in order to perform a smooth and highly rigid tilt motion or telescopic motion. A spherical joint comprising a cylindrical bush and a cylindrical sleeve into which the bush is inserted is provided in the power transmission path from the electric motor to the column. In this spherical joint, in order to close the gap between the ball and the bush and the gap between the bush and the sleeve and eliminate the play, an adjustment screw is screwed into the slit formed in the ball, The outer dimensions of the ball are expanded or reduced by increasing or decreasing the groove width.

  However, in the electric steering device of Patent Document 1, when the groove width of the ball slit is increased or decreased, a large stress acts on the groove bottom of the slit to cause stress concentration, which may reduce the durability of the ball. .

JP 2006-36043 A

  It is an object of the present invention to provide an electric steering device capable of reducing stress concentration generated at the groove bottom of a ball slit constituting a spherical joint.

The above problem is solved by the following means. That is, the first invention is a steering shaft on which a steering wheel is mounted on the rear side of the vehicle body, the steering shaft is rotatably supported, and the tilt position is adjusted with the tilt center axis as a fulcrum. In an electric steering device including a column capable of adjusting a telescopic position along a central axis, an electric motor, and a power transmission mechanism for transmitting rotation of the electric motor as tilt movement or telescopic movement of the column. transmission mechanism includes a ball screw rotationally driven by the electric motor, the ball nut screwed to the ball screw, a ball which forms a spherical projection provided on the ball nut, the ball is fitted to the inner peripheral A cylindrical bush having a concave spherical surface Over the entire axial length, and the bushing in which slits are formed to scale the size of the bush, a cylindrical sleeve the bush is inserted through the axial center of the ball, parallel to the axis center Also, two slits extending in the direction of the corner of the side surface of the ball nut perpendicular to each other , the ball being divided into four with respect to the axis , and having an R surface formed at the groove bottom, and the groove width of the slit of the ball Adjusting screws for expanding and contracting the outer dimensions of the ball, and a clearance between the outer periphery of the ball and the concave spherical surface of the inner periphery of the bush, and the outer periphery of the bush and the sleeve The electric steering device is characterized in that the gap with the inner periphery can be adjusted by adjusting the screwing depth of the adjusting screw.

The second aspect is the electric steering apparatus according to the first aspect of the invention, is formed larger than the groove width of the slit the R surface having a diameter dimension of the slit formed in the groove bottom of the ball This is an electric steering device.

  An electric steering apparatus according to the present invention includes a screw that is rotationally driven by an electric motor, and a screw in an electric steering apparatus that includes a power transmission mechanism that transmits rotation of the electric motor as a column tilt motion or telescopic motion. A cylindrical bush having a spherical protrusion provided on the nut, and a concave spherical surface with which the ball fits on the inner periphery, the bush extending over the entire length in the axial direction. A bush formed with a slit for enlarging or reducing the diameter of the ball, a cylindrical sleeve into which the bush is inserted, a slit formed on the ball and having an R surface on the groove bottom, and a groove width of the ball slit And an adjusting screw for expanding / reducing the outer dimension of the ball. Therefore, when the groove width of the slit is increased, a large stress acts on the groove bottom of the slit, but since the R surface is formed on the groove bottom, stress concentration does not occur on the groove bottom of the slit. Improves durability.

1 is an overall perspective view showing a state where an electric steering device of the present invention is attached to a vehicle. It is a principal part schematic block diagram including a partial cross section which shows the electric tilt type steering apparatus of Example 1 of this invention. It is AA sectional drawing of FIG. FIG. 6 is an explanatory diagram illustrating a tilt operation according to the first exemplary embodiment. It is an expanded sectional view of the spherical joint which shows the state before screwing an adjustment screw. It is a front view of the integrally molded product of the ball | bowl and ball nut of Example 1 of this invention. (A) is a front view which shows the state which rotated the 45-degree integral molded product of the ball | bowl and ball nut of FIG. 6, (b) is a right view of (a). It is a side view which shows the bush single body seen from the P direction of FIG. It is an expanded sectional view of the spherical joint which shows the state after screwing the adjustment screw. (A) is a front view which shows the integrally molded product of the ball | bowl and ball nut of Example 2 of this invention, (b) is a right view of (a).

    Hereinafter, Example 1 to Example 2 of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall perspective view showing a state in which an electric steering device 1 of the present invention is attached to a vehicle. The electric steering device 1 rotatably supports a steering shaft 2. A steering wheel 3 is attached to the steering shaft 2 at the right end (rear side of the vehicle body), and an intermediate shaft 102 is connected to the left end of the steering shaft 2 (front side of the vehicle body) via a universal joint 101.

  A universal joint 103 is connected to the left end of the intermediate shaft 102, and a steering gear 104 including a rack and pinion mechanism is connected to the universal joint 103.

  When the driver rotates the steering wheel 3, the rotational force is transmitted to the steering gear 104 via the steering shaft 2, the universal joint 101, the intermediate shaft 102, and the universal joint 103, and the tie rod is transmitted via the rack and pinion mechanism. 105 can be moved to change the steering angle of the wheel.

  FIG. 2 is a schematic configuration diagram of a main part including a partial cross section showing the electric tilt type steering apparatus according to the first embodiment of the present invention. 3 is a cross-sectional view taken along the line AA in FIG. FIG. 4 is an explanatory diagram illustrating the tilting operation of the first embodiment. FIG. 5 is an enlarged cross-sectional view of the spherical joint showing a state before the adjustment screw is screwed. FIG. 6 is a front view of an integrally molded product of a ball and a ball nut according to the first embodiment of the present invention. FIG. 7A is a front view showing a state in which the integrally molded product of the ball and ball nut of FIG. 6 is rotated by 45 degrees, and FIG. 7B is a right side view of FIG. FIG. 8 is a side view showing a single bush viewed from the direction P in FIG. FIG. 9 is an enlarged cross-sectional view of the spherical joint showing a state after the adjusting screw is screwed in.

  On the left side (front side of the vehicle body) of FIG. 2, an attachment portion 511 formed on the upper portion of the T-shaped lower vehicle body attachment bracket 51 is fixed to the vehicle body 53, and the pivot portion 512 is downwardly moved from the attachment portion 511. It extends. The left end of the column 4 is swingably supported by the lower vehicle body mounting bracket 51 with a pivot pin 513 pivotally supported by the pivot portion 512 as a fulcrum.

  On the right side (rear side of the vehicle body) in FIG. 2, an attachment portion 521 formed on the upper portion of the L-shaped upper vehicle body attachment bracket 52 is fixed to the vehicle body 53, and the column support portion 522 is downward from the attachment portion 521. It extends to. As shown in FIG. 3, the column support portion 522 has a long hole 523 that is long in the vertical direction. The right end of the cylindrical column 4 extends through the long hole 523 to the right side of FIG. When the tilt position is adjusted, the right end of the column 4 can freely move in the vertical direction in the elongated hole 523. A steering shaft 2 is rotatably supported on the column 4, and a steering wheel 3 is mounted on the steering shaft 2 at the right end (rear side of the vehicle body).

  A U-shaped bracket 41 is integrally formed on the left side surface of the column 4, and an electric motor 61 is fixed to the bracket 41. In addition, the upper and lower ends of the ball screw 71 are pivotally supported by the upper shaft support portion 41A and the lower shaft support portion 41B of the bracket 41 via rolling bearings (not shown).

  A worm gear 62 is integrally formed on the output shaft 611 of the electric motor 61, and a worm wheel 72 fixed to the ball screw 71 is engaged with the worm gear 62. The worm wheel 72 and the worm gear 62 constitute a speed reduction mechanism, and the rotation of the electric motor 61 is decelerated and transmitted to the ball screw 71.

  A ball nut 73 that converts the rotation of the ball screw 71 into a linear motion is screwed into the ball screw 71. The feed mechanism composed of the ball screw 71 and the ball nut 73 includes a plurality of balls interposed between the spiral groove on the outer periphery of the ball screw 71 and the spiral groove on the inner periphery of the ball nut 73. This is a feed mechanism that converts the rotation into a linear motion of the ball nut 73.

  Since the ball is interposed, there is no backlash between the ball screw 71 and the ball nut 73, so the column 4 has no backlash and the steering wheel 3 feels good. In addition, since the feed resistance is small and the variation in the feed resistance is small, the tilt position can be adjusted smoothly.

  A ball 74 having a spherical projection is integrally formed on the ball nut 73 on the right side of FIG. As seen from FIG. 2, a cylindrical sleeve 75 is integrally formed on the left end surface 522A of the column support portion 522, and a ball 74 is slidably fitted into the sleeve 75 to constitute a spherical joint. .

  As shown in FIGS. 5, 8, and 9, a cylindrical bush 76 is interposed between the outer periphery 74 </ b> B of the ball 74 and the inner periphery 75 </ b> A of the sleeve 75. On the inner periphery of the bush 76, a concave spherical surface 76A that is closely joined to the spherical outer periphery 74B of the ball 74 is formed. A slit 761 (see FIG. 8) is formed in the bush 76 over the entire length in the axial direction of the bush 76 so that the bush 76 can be easily enlarged and reduced in the radial direction. In order to smoothly rotate the ball 74 along the concave spherical surface 76A of the bush 76, the bush 76 may be formed of a synthetic resin having a small friction coefficient, an oil-impregnated bearing material, or coated with a low friction material. preferable.

  As shown in FIGS. 5 to 7, the ball 74 has a slit 741 having a groove width W. The slit 741 passes through the axis of the ball 74 (the left-right direction in FIGS. 5 to 6) and is formed parallel to the axis. An R surface 742 having a diameter larger than the groove width W is formed at the groove bottom (left end in FIGS. 5 to 6) of the slit 741. Further, a female screw 77 is formed in the left-right direction of FIGS. 5 to 6 at the axial center of the ball 74, and a tapered counterbore 771 is formed at the right end of the female screw 77.

  The adjustment screw 78 to be screwed into the female screw 77 is a countersunk screw having a tapered tightening surface 781 of the screw head. The taper angle R of the tightening surface 781 of the adjustment screw 78 is larger than the taper angle Q of the counterbore 771. When the adjusting screw 78 is screwed into the female screw 77, the tightening surface 781 pushes the counterbore 771 outward in the radial direction, thereby pushing the slit 741 up and down in FIGS.

  Therefore, by appropriately adjusting the screwing depth of the adjusting screw 78, the groove width W of the slit 741 can be expanded and reduced, and the outer dimension of the ball 74 can be expanded or reduced. As shown in FIG. 5, a gap b is formed between the outer periphery 76 </ b> B of the bush 76 and the inner periphery 75 </ b> A of the sleeve 75 before the adjustment screw 78 is screwed into the female screw 77.

  As shown in FIG. 9, when the adjusting screw 78 is screwed into the female screw 77, the groove width W of the slit 741 is enlarged, and the gap b between the outer periphery 76B of the bush 76 and the inner periphery 75A of the sleeve 75 can be eliminated. In addition, a gap between the outer circumference 74B of the ball 74 and the concave spherical surface 76A of the bush 76 can be eliminated. When the groove width W of the slit 741 increases, a large stress acts on the groove bottom of the slit 741. However, since the R surface 742 is formed at the groove bottom, stress concentration does not occur at the groove bottom of the slit 741, and the durability of the ball 74 is improved.

  Even if there is a manufacturing error in the fitting dimensions of the ball 74, the bush 76, and the sleeve 75, by adjusting the screwing depth of the adjusting screw 78 as appropriate, the dimensional error between the parts can be absorbed, Therefore, the steering feeling of the steering wheel 3 is improved and the manufacture of each component is facilitated, so that the manufacturing cost can be reduced.

  2 and 5 is the same as the load direction applied to the ball 74 when adjusting the tilt position of the steering wheel 3, so that a load is applied when adjusting the tilt position. The gap adjustment by the adjustment screw 78 can be performed in consideration of the fluctuation of the gap between the parts at the time.

  Further, by appropriately selecting the depth L1 of the counterbore 771 and the height L2 of the tightening surface 781, the coupling rigidity between the adjusting screw 78 and the ball 74, that is, the rigidity of the slit 74 can be adjusted as appropriate. .

  When it is necessary to adjust the tilt position of the steering wheel 3, when the switch (not shown) is operated, the electric motor 61 is rotationally driven in either the forward or reverse direction. Then, the rotation of the electric motor 61 is decelerated and transmitted from the worm gear 62 to the worm wheel 72, and the ball screw 71 integrated with the worm wheel 72 rotates, for example, the ball nut 73 moves along the ball screw 71. 2 in the axial direction.

  Then, the ball 74 integral with the ball nut 73 is also lowered with respect to the column 4, and the ball 74 is fitted to the bush 76, so that the column 4 is tilted upward as shown in FIG. Further, when the ball 74 rises, the column 4 tilts downward. When the column 4 is tilted, the ball 74 freely rotates and slides within the concave spherical surface 76A of the bush 76, so that the tilt movement of the column 4 is hindered or unnecessary between the ball 74 and the bush 76. There is no stress or friction.

  FIG. 10A is a front view showing an integrally molded product of a ball and a ball nut according to the second embodiment of the present invention, and FIG. 10B is a right side view of FIG. 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. The second embodiment is a modification of the first embodiment, in which two slits are formed.

  As shown in FIG. 10, the ball 74 is formed with slits 741 and 743 having a groove width W. The slits 741 and 743 pass through the axis of the ball 74 (the left-right direction in FIG. 10A) and are formed parallel to the axis. The slits 741 and 743 are formed orthogonal to each other, and divide the ball 74 into four parts. R surfaces 742 and 744 having a diameter larger than the groove width W are formed at the groove bottoms of the slits 741 and 743 (left end in FIG. 10A). Further, a female screw 77 is formed in the left and right direction of FIG. 10A at the axial center of the ball 74, and a tapered counterbore 771 is formed at the right end of the female screw 77.

  Although not shown, when the adjusting screw 78 having the same shape as that of the first embodiment is screwed into the female screw 77, the groove width W of the slits 741 and 743 is increased, and the clearance between the outer periphery 76B of the bush and the inner periphery 75A of the sleeve 75 is increased. And the clearance gap between the outer periphery 74B of the ball | bowl 74 and the concave spherical surface 76A of the bush 76 can be eliminated. When the groove width W of the slits 741 and 743 is increased, a large stress acts on the groove bottoms of the slits 741 and 743. However, since the R surfaces 742 and 744 are formed at the groove bottom, stress concentration does not occur at the groove bottoms of the slits 741 and 743, and the durability of the ball 74 is improved.

  In the second embodiment of the present invention, since the ball 74 is divided into four by the two slits 741 and 743, the outer dimension of the ball 74 is spherical when the adjusting screw 78 is adjusted to enlarge or reduce the outer dimension of the ball 74. The shape approximated to is maintained and scaled. Therefore, the contact area between the concave spherical surface 76A of the bush 76 and the outer periphery 74B of the ball 74 is increased, and the contact surface pressure is reduced, which is preferable.

  In the embodiment of the present invention, the example applied to the electric tilt type steering apparatus for adjusting the tilt position of the steering wheel has been described. However, the electric telescopic type steering apparatus for adjusting the telescopic position of the steering wheel and the tilt position of the steering wheel The present invention may also be applied to an electric tilt / telescopic steering device that adjusts both the telescopic position and the telescopic position.

DESCRIPTION OF SYMBOLS 1 Electric steering apparatus 101 Universal joint 102 Intermediate shaft 103 Universal joint 104 Steering gear 105 Tie rod 2 Steering shaft 3 Steering wheel 4 Column 41 Bracket 41A Upper shaft support part 41B Lower shaft support part 51 Lower vehicle body mounting bracket 511 Mounting part 512 Pivot part 513 Pivot Pin 52 Upper body mounting bracket 521 Mounting portion 522 Column support portion 522A Left end surface 523 Long hole 53 Car body 61 Electric motor 611 Output shaft 62 Worm gear 71 Ball screw 72 Warm wheel 73 Ball nut 74 Ball 74B Outer periphery 741 Slit 742 R surface 743 Slit 744 R surface 75 Sleeve 75A Inner circumference 76 Bush 76A Concave spherical surface 76B Outer circumference 761 Slit 77 Female thread 771 Counterbore 78 Adjustment screw 781 Tightening surface

Claims (2)

A steering shaft with a steering wheel mounted on the rear side of the vehicle body,
A column capable of pivoting the steering shaft and adjusting the tilt position with the tilt center axis as a fulcrum, or telescopic position adjustment along the center axis of the steering shaft,
Electric motor,
In the electric steering apparatus provided with a power transmission mechanism that transmits the rotation of the electric motor as a tilting motion of the column or a telescopic motion,
The power transmission mechanism is
A ball screw that is rotationally driven by the electric motor;
A ball nut screwed into the ball screw;
A ball having a spherical protrusion provided on the ball nut;
A cylindrical bush having a concave spherical surface with which the ball fits on the inner periphery, and a bush formed with a slit for enlarging or reducing the diameter of the bush over the entire length in the axial direction;
A cylindrical sleeve into which the bush is inserted;
The ball passes through the axis of the ball, extends parallel to the axis and perpendicular to each other in the direction of the corner of the side surface of the ball nut , the ball is divided into four with respect to the axis , and an R surface is formed at the groove bottom. Two slits,
An adjustment screw for enlarging / reducing the outer dimension of the ball by enlarging / reducing the groove width of the slit of the ball,
The clearance between the outer periphery of the ball and the concave spherical surface on the inner periphery of the bush and the clearance between the outer periphery of the bush and the inner periphery of the sleeve can be adjusted by adjusting the screwing depth of the adjusting screw. A featured electric steering device. In the electric steering device according to claim 1,
An electric steering apparatus, wherein a diameter dimension of the R surface formed on a groove bottom of the slit of the ball is formed larger than a groove width of the slit.

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