JP2007261487A - Electric steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric steering device preventing fluctuation of preload applied to a rotating shaft and an input shaft of a speed reduction mechanism even when temperature is changed and having an electric motor suppressing increase in a load current. <P>SOLUTION: Even when the temperatures of the electric motor 6 and a housing 65 are changed, since materials of a motor case 61, the rotating shaft 64 and a worm gear 66 have approximately equal thermal expansion coefficients, the thermal deformation quantities of the motor case 61, the rotating shaft 64 and the worm gear 66 do not vary with each other and the preload applied to the worm gear 66 and the rotating shaft 64 by a deep groove type radial ball bearing 68 and a slide thrust bearing 673 is not increased/decreased. Therefore, even when the temperature is changed, since increase in load applied to the rotating shaft 64 during operation of the electric motor 6 can be suppressed, increase in the load current of the electric motor 6 can be suppressed. <P>COPYRIGHT: (C)2008,JPO&INPIT

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. Type steering device.

  The electric motor of such an electric steering device decelerates the rotation of the electric motor by a reduction mechanism composed of a worm gear and a worm wheel, and transmits it as a column tilt motion or telescopic motion. Since the direction of the axial thrust force acting on the worm gear changes during forward rotation and reverse rotation, the worm gear may move in the axial direction and generate noise.

  In order to eliminate such abnormal noise of the worm gear, electric motors disclosed in Patent Document 1 and Patent Document 2 are provided as electric motors in which preload is applied to the worm gear to eliminate axial play of the worm gear. There is.

  FIG. 8 is a cross-sectional view of the electric motor disclosed in Patent Document 1 and Patent Document 2. As shown in FIG. 8, the conventional electric motor 6 has a bottomed cylindrical motor case 61, and a magnet 62 is fixed to an inner peripheral surface 611 of the motor case 61. Inside the magnet 62, an armature 63 having a rotor core and a rotor coil is rotatably accommodated.

  The armature 63 has a rotation shaft 64 at its axis. The motor case 61 also serves as a yoke for the magnet 62, and a flange portion 651 of the housing 65 is coupled to a flange portion 612 at the left end of the motor case 61 by a bolt (not shown). The housing 65 is made of aluminum and incorporates a speed reduction mechanism.

  At the left end (left side in FIG. 8) of the rotation shaft 64, a worm gear (input shaft of the speed reduction mechanism) 66 is integrally formed on the same axis as the rotation shaft 64, and the worm gear 66 is in the housing 65 (left side in FIG. 8). It extends to. The worm gear 66 meshes with the worm wheel 72 to form a reduction mechanism, and the rotation of the rotary shaft 64 of the electric motor 6 is reduced and transmitted to the feed screw 71. The motor case 61 and the rotating shaft 64 (the worm gear 66 integral with the rotating shaft 64) are made of an iron-based material having substantially the same thermal expansion coefficient.

  The outer periphery of the rotation shaft 64 is rotatably supported by a slide bearing (journal bearing that supports only a radial load) 671. The outer periphery of the sliding bearing 671 is press-fitted into the right end of the motor case 61, and the fitting between the outer periphery of the rotating shaft 64 and the inner periphery of the sliding bearing 671 is a clearance fit.

  The left end of the rotating shaft 64 (the position where the rotating shaft 64 protrudes from the flange portion 612 of the motor case 61 and the vicinity of the position where the rotating shaft 64 is connected to the worm gear 66) can be rotated by the deep groove radial ball bearing 68. Is pivotally supported. The fitting between the outer periphery of the rotating shaft 64 and the inner periphery of the inner ring 681 of the deep-groove radial ball bearing 68 is a clearance fit.

  The outer periphery of the outer ring 682 of the deep groove radial ball bearing 68 is fitted in an annular recess 652 formed in the flange portion 651 of the housing 65. The left end surface of the outer ring 682 of the deep groove radial ball bearing 68 is in contact with the bottom surface 653 of the annular recess 652. The fitting between the outer ring 682 and the annular recess 652 of the deep groove radial ball bearing 68 is an interference fit.

  The outer periphery of the left end portion 661 of the worm gear 66 is rotatably supported by a slide bearing (journal bearing that supports only a radial load) 672. The outer periphery of the slide bearing 672 is press-fitted into an annular recess 654 formed at the left end of the housing 65, and the fit between the outer periphery of the left end portion 661 of the worm gear 66 and the inner periphery of the slide bearing 672 is a clearance fit. Yes.

  A preload adjusting screw 69 is screwed into the left end of the housing 65, and a sliding thrust bearing 673 is interposed between the end surface 691 of the preload adjusting screw 69 and the left end surface 662 of the left end portion 661 of the worm gear 66. Yes. Further, a sliding thrust bearing 674 is inserted between the right end of the motor case 61 and the right end surface 641 of the rotating shaft 64. The sliding thrust bearings 673 and 674 are formed of a resin material having a small friction coefficient and excellent wear resistance.

  When the preload adjusting screw 69 is appropriately screwed and the worm gear 66 is pressed to the right via the sliding thrust bearing 673 and then the lock nut 692 is tightened to fix the preload adjusting screw 69 to the left end of the housing 65, The right end face 641 is strongly pressed against the sliding thrust bearing 674. Accordingly, the worm gear 66 and the rotary shaft 64 are pre-loaded with the sliding force in the left and right directions in FIG. 8 by the sliding thrust bearing 674 and the sliding thrust bearing 673, and are free from backlash.

  However, when the temperature of the electric motor 6 and the housing 65 changes, the aluminum housing 65 has a thermal expansion coefficient larger than that of the motor case 61, the rotating shaft 64, and the worm gear 66 formed of an iron-based material. The amount is large. Therefore, the preload acting on the worm gear 66 and the rotating shaft 64 increases at a low temperature, and the preload acting on the worm gear 66 and the rotating shaft 64 decreases at a high temperature.

  Accordingly, when the temperature is high, the worm gear 66 and the rotating shaft 64 move in the axial direction due to the backlash in the axial direction of the worm gear 66 and the rotating shaft 64, thereby generating noise. In addition, when the temperature is low, the load applied to the rotating shaft 64 is increased when the electric motor 6 is operated due to the increase of the preload.

Japanese Patent Laid-Open No. 10-271753 JP 2001-69714 A

  It is an object of the present invention to provide an electric steering device having an electric motor that suppresses an increase in load current without fluctuations in preload applied to a rotating shaft and an input shaft of a speed reduction mechanism even when temperature changes. To do.

  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, or the steering shaft A column capable of telescopic position adjustment along the central axis, an electric motor, a rotating shaft rotatably supported by a motor case of the electric motor, a rotation of the rotating shaft, decelerating rotation of the column, Alternatively, in the electric steering apparatus including a housing that is coupled to the motor case and includes a reduction mechanism that transmits the telescopic motion, the rotation shaft of the electric motor and the input shaft of the reduction mechanism are formed on the same axis. The rotating shaft and the input shaft are connected by a bearing provided closer to the electric motor than the input shaft. It is an electric steering apparatus according to claim preload on both sides in the axial direction is applied.

  A second aspect of the 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 central axis as a fulcrum, or the center of the steering shaft A column capable of telescopic position adjustment along the axis, an electric motor, a rotary shaft rotatably supported by a motor case of the electric motor, a rotation of the rotary shaft, decelerating the rotation of the column, or In the electric steering apparatus including a housing that is coupled to the motor case and that has a built-in reduction mechanism that transmits the telescopic movement, the rotation shaft of the electric motor and the input shaft of the reduction mechanism are formed on the same axis, and the rotation The shaft is supported by bearings at both ends in the axial direction, and the shaft of the bearing that supports the rotating shaft is supported. That is, the bearing on the input shaft side supports the rotating shaft so as not to move in the axial direction, and the bearing on the counter-input shaft side among the bearings supporting the rotating shaft supports the rotating shaft and rotates the rotating shaft. The electric steering device is characterized in that a preload is applied to an end of the shaft on the side opposite to the input shaft toward the input shaft.

  According to a third aspect of the present invention, in the electric steering apparatus of the first or second aspect of the invention, the input shaft of the speed reduction mechanism has an end on the opposite side of the electric motor connected to the housing of the speed reduction mechanism. An electric steering device is supported by a shaft so as to be movable in an axial direction.

  According to a fourth aspect of the present invention, there is provided the electric steering apparatus according to any one of the first and second aspects, wherein the rotating shaft and the input shaft of the speed reduction mechanism are integrally formed. It is a steering device.

  According to a fifth aspect of the present invention, in the electric steering device of the first or second aspect, the rotation shaft and the input shaft of the speed reduction mechanism are formed separately, and the input shaft of the speed reduction mechanism is formed from the rotation shaft. The electric steering device is connected to each other so that rotational torque can be transmitted to each other.

  According to a sixth aspect of the present invention, in the electric steering device of the first or second aspect, the motor case and the rotating shaft of the electric motor are formed of a material having substantially the same thermal expansion coefficient. This is an electric steering device.

  A seventh aspect of the invention is the electric steering device according to the first or second aspect of the invention, wherein the input shaft has a worm gear formed on the input shaft, and the column is tilted via a worm wheel meshing with the worm gear. Alternatively, the electric steering device is characterized in that telescopic motion is transmitted.

  An eighth aspect of the invention is the electric steering apparatus according to any one of the third to sixth aspects, wherein a worm gear is formed on the input shaft, and the column is tilted via a worm wheel meshing with the worm gear. It is an electric steering apparatus characterized in that movement or telescopic movement is transmitted.

  In the electric steering device of the present invention, the rotational axis of the electric motor and the input shaft of the speed reduction mechanism formed on the same axis are preloaded on both sides in the axial direction by bearings provided on the electric motor side of the input shaft. Is granted. Therefore, even if the temperature changes, there is no fluctuation in the preload applied to the rotating shaft of the electric motor and the input shaft of the speed reduction mechanism, and an increase in the load applied to the rotating shaft during operation of the electric motor can be suppressed. An increase in current can be suppressed.

  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. As shown in FIG. 1, the electric steering device 1 pivotally 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 105 is transmitted via the rack and pinion mechanism. 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 an electric tilt type steering apparatus that adjusts the tilt position of the steering wheel 3 with an electric motor.

  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. The column support portion 522 holds the left and right side surfaces of the column 4 so that the tilt position can be adjusted. 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 bracket 41 is formed integrally with the column 4, and an electric motor 6 as an electric actuator is fixed to the bracket 41. In addition, the upper and lower ends of the feed screw 71 are pivotally supported by the upper shaft support portion 41A and the lower shaft support portion 41B of the bracket 41 via a rolling bearing (not shown).

  A worm gear 66 is integrally formed on the rotating shaft 64 of the electric motor 6, and a worm wheel 72 fixed to the feed screw 71 is engaged with the worm gear 66. The worm wheel 72 and the worm gear 66 constitute a speed reduction mechanism, and the rotation of the electric motor 6 is decelerated and transmitted to the feed screw 71.

  A nut 73 that converts the rotation of the feed screw 71 into a linear motion is screwed to the feed screw 71. The feed mechanism including the feed screw 71 and the nut 73 is a feed mechanism that converts the rotation of the feed screw 71 into a linear motion of the nut 73.

  A ball 74 having a spherical protrusion is integrally formed on the nut 73 on the right side of FIG. A cylindrical sleeve 75 is integrally formed on the left end surface 522A (as viewed from FIG. 2) of the column support portion 522, and the outer periphery of the ball 74 is slidably fitted into the inner periphery 75A of the sleeve 75. It constitutes a spherical joint.

  When it is necessary to adjust the tilt position of the steering wheel 3, when a switch (not shown) is operated, the rotating shaft 64 of the electric motor 6 is rotationally driven in either the forward or reverse direction. Then, the rotation of the rotating shaft 64 of the electric motor 6 is transmitted by decelerating from the worm gear 66 to the worm wheel 72, and the feed screw 71 integrated with the worm wheel 72 rotates, for example, the nut 73 becomes the feed screw 71. Along the axis.

  Then, the ball 74 integral with the nut 73 is also lowered with respect to the column 4 and the ball 74 is fitted to the sleeve 75, so that the column 4 is tilted upward. Further, when the ball 74 rises, the column 4 tilts downward. When the column 4 is tilted, the ball 74 is freely rotated and slid within the inner circumference 75A of the sleeve 75, so that the tilt movement of the column 4 is obstructed and is unnecessary between the ball 74 and the sleeve 75. There is no stress or friction.

  FIG. 3 is a schematic configuration diagram of a main part including a partial cross section showing an electric telescopic steering device that adjusts the telescopic position of the steering wheel 3 with an electric motor. FIG. 4 is a bottom view of FIG.

  An inner column 43 is fitted to the hollow cylindrical outer column 42 so as to be telescopically slidable in the axial direction (left-right direction in FIG. 3). A rectangular opening 45 is formed in the lower portion of the outer column 42, and a sleeve 75 fixed to the inner column 43 protrudes outward through the opening 45. The opening 45 functions as a stopper when the outer periphery of the sleeve 75 comes into contact with the front end 45A and the rear end 45B of the opening 45 when adjusting the telescopic position, and also functions to prevent the inner column 43 from rotating in the rotational direction. Also plays.

  A steering shaft 2 is rotatably supported on the inner column 43, and a steering wheel 3 is mounted on the steering shaft 2 at the right end (rear side of the vehicle body). A front shaft support portion 44A and a rear shaft support portion 44B are integrally formed on the lower surface of the outer column 42 so as to protrude forward and backward with the opening 45 therebetween, and both front and rear ends of the feed screw 71 via a rolling bearing (not shown). Are pivotally supported. The electric motor 6 is fixed to the side surface of the outer column 42.

  A worm gear 66 is integrally formed on the rotating shaft 64 of the electric motor 6, and a worm wheel 72 fixed to the feed screw 71 is engaged with the worm gear 66. The worm wheel 72 and the worm gear 66 constitute a speed reduction mechanism, and the rotation of the electric motor 6 is decelerated and transmitted to the feed screw 71.

  A nut 73 that converts the rotation of the feed screw 71 into a linear motion is screwed to the feed screw 71. The nut 73 is integrally formed with a ball 74 having a spherical projection on the upper side, and the outer periphery of the ball 74 is slidably fitted into the inner periphery 75A of the sleeve 75 to constitute a spherical joint. is doing.

  When it is necessary to adjust the telescopic position of the steering wheel 3, when the switch (not shown) is operated, the electric motor 6 is rotationally driven in either the forward or reverse direction. Then, the rotation of the electric motor 6 is decelerated and transmitted from the worm gear 66 to the worm wheel 72, and the feed screw 71 integral with the worm wheel 72 rotates, for example, the nut 73 moves along the feed screw 71 to the left. Move in the direction (vehicle front side).

  Then, the ball 74 integral with the nut 73 also moves leftward, and the ball 74 is fitted to the sleeve 75, so that the inner column 43 telescopically moves leftward. Further, when the ball 74 moves in the right direction (rear side of the vehicle body), the inner column 43 moves telescopically in the right direction. When the inner column 43 moves telescopically, the ball 74 freely rotates and slides within the inner circumference 75A of the sleeve 75, so that the telescopic movement of the inner column 43 is hindered, or between the ball 74 and the sleeve 75, Unnecessary stress and friction are not generated.

  Next, the detailed structure of the electric motor 6 according to the first embodiment of the present invention will be described.

  FIG. 5 is a cross-sectional view of the electric motor 6 according to the first embodiment of the present invention. The electric motor 6 has a bottomed cylindrical motor case 61, and a magnet 62 is fixed to an inner peripheral surface 611 of the motor case 61. Inside the magnet 62, an armature 63 having a rotor core and a rotor coil is rotatably accommodated.

  The armature 63 has a rotation shaft 64 at its axis. The motor case 61 also serves as a yoke for the magnet 62, and a flange portion 651 of the housing 65 is coupled to a flange portion 612 at the left end of the motor case 61 by a bolt (not shown). The housing 65 is made of aluminum and incorporates a speed reduction mechanism.

  At the left end (left side in FIG. 5) of the rotation shaft 64, a worm gear (input shaft of the speed reduction mechanism) 66 is integrally formed on the same axis as the rotation shaft 64, and the worm gear 66 is in the housing 65 (left side in FIG. 5). It extends to. The worm gear 66 meshes with the worm wheel (output shaft of the speed reduction mechanism) 72 described above to form a speed reduction mechanism. The speed of the rotation shaft 64 of the electric motor 6 is reduced and transmitted to the feed screw 71. The motor case 61 and the rotating shaft 64 (the worm gear 66 integral with the rotating shaft 64) are made of an iron-based material having substantially the same thermal expansion coefficient.

  The outer periphery of the rotation shaft 64 is rotatably supported by a slide bearing (journal bearing that supports only a radial load) 671. The outer periphery of the sliding bearing 671 is press-fitted into the right end of the motor case 61, and the fitting between the outer periphery of the rotating shaft 64 and the inner periphery of the sliding bearing 671 is a clearance fit.

  The left end of the rotating shaft 64 (the position where the rotating shaft 64 protrudes from the flange portion 612 of the motor case 61 and the vicinity of the position where the rotating shaft 64 is connected to the worm gear 66) is rolling of a deep groove radial ball bearing 68 or the like. It is rotatably supported by a bearing. The deep groove radial ball bearing 68 is press-fitted into the outer periphery of the rotary shaft 64, and the fit between the outer periphery of the rotary shaft 64 and the inner periphery of the inner ring 681 of the deep groove radial ball bearing 68 is an interference fit.

  The outer periphery of the outer ring 682 of the deep groove radial ball bearing 68 is fitted in an annular recess 652 formed in the flange portion 651 of the housing 65. The left end surface of the outer ring 682 of the deep groove radial ball bearing 68 is in contact with the bottom surface 653 of the annular recess 652. The outer ring 682 and the annular recess 652 of the deep groove radial ball bearing 68 may be fitted to each other by an interference fit or a clearance fit.

  The outer periphery of the left end portion 661 of the worm gear 66 is rotatably supported by a slide bearing (journal bearing that supports only a radial load) 672. The outer periphery of the slide bearing 672 is press-fitted into an annular recess 654 formed at the left end of the housing 65, and the fit between the outer periphery of the left end portion 661 of the worm gear 66 and the inner periphery of the slide bearing 672 is a clearance fit. Yes. Further, a gap δ is formed between the bottom surface 655 of the annular recess 654 and the left end surface 662 of the left end portion 661 of the worm gear 66.

  A preload adjusting screw 69 is screwed into the right end of the motor case 61, and a sliding thrust bearing 673 is interposed between the end surface 691 of the preload adjusting screw 69 and the right end surface 641 of the rotating shaft 64. The sliding thrust bearing 673 is formed of a resin material having a small friction coefficient and excellent wear resistance.

  When the preload adjusting screw 69 is properly screwed in and the rotary shaft 64 is pressed to the left via the sliding thrust bearing 673, the lock nut 692 is tightened, and the preload adjusting screw 69 is fixed to the right end of the motor case 61. The left end surface of the outer ring 682 of the radial ball bearing 68 is strongly pressed against the bottom surface 653 of the annular recess 652 of the housing 65.

  Accordingly, the worm gear 66 and the rotating shaft 64 are pre-loaded against the thrust force in both the left and right directions in FIG. 5 by the deep-groove radial ball bearing 68 and the sliding thrust bearing 673 so that there is no backlash. That is, a deep groove radial ball bearing 68 that applies preload to the worm gear 66 and the rotating shaft 64 and a sliding thrust bearing 673 are arranged closer to the electric motor 6 than the worm gear 66.

  In this state, even if the temperature of the electric motor 6 and the housing 65 changes, the motor case 61, the rotating shaft 64, and the worm gear 66 are formed of materials having substantially the same thermal expansion coefficient. There is no difference, and the preload applied to the worm gear 66 and the rotary shaft 64 is not increased or decreased by the deep groove radial ball bearing 68 and the sliding thrust bearing 673. Therefore, even if the temperature changes, an increase in load applied to the rotating shaft during operation of the electric motor can be suppressed, so that an increase in load current of the electric motor 6 can be suppressed. Further, since a gap δ is formed between the bottom surface 655 of the annular recess 654 and the left end surface 662 of the worm gear 66, the difference in the amount of thermal deformation between the worm gear 66 and the housing 65 can be absorbed.

  In the first embodiment, the bearings 671, 672, and 673 are sliding bearings, but may be rolling bearings such as ball bearings and roller bearings. Further, the deep groove radial ball bearing 68 may be an angular radial ball bearing.

  Next, a second embodiment of the present invention will be described. The second embodiment is a modification of the first embodiment, and is an example in which all bearings for applying preload to the worm gear 66 and the rotating shaft 64 are arranged on the motor case 61 side. In the following description, only structural portions and operations different from those of the first embodiment will be described, and overlapping descriptions will be omitted. The same parts as those in the first embodiment will be described with the same numbers.

  FIG. 6 is a sectional view of the electric motor 6 according to the second embodiment of the present invention. As shown in FIG. 6, the outer periphery of the outer ring 682 of the deep groove-shaped radial ball bearing 68 that supports the vicinity of the position where the rotating shaft 64 is connected to the worm gear 66 is not the flange portion 651 side of the housing 65, but the motor case 61. Is fitted into an annular recess 613 formed in the flange portion 612. The left end surface of the outer ring 682 of the deep groove radial ball bearing 68 is in contact with the bottom surface 614 of the annular recess 613. The outer ring 682 of the deep groove radial ball bearing 68 and the annular recess 613 may be fitted to each other by an interference fit or a clearance fit.

  Further, the fitting of the outer periphery of the rotating shaft 64 and the inner periphery of the inner ring 681 of the deep groove radial ball bearing 68 may be an interference fit as in the first embodiment, but may be a clearance fit. The deep groove radial ball bearing 68 supports the rotating shaft 64 inside the motor case 61. Further, a step surface 642 is formed on the rotating shaft 64, and the step surface 642 is in contact with the right end surface of the inner ring 681 of the deep groove radial ball bearing 68.

  When the preload adjusting screw 69 is appropriately screwed and the rotating shaft 64 is pressed to the left via the sliding thrust bearing 673, the deep radial radial ball bearing 68 is pressed to the left by the step surface 642 of the rotating shaft 64, and the depth groove The left end surface of the outer ring 682 of the radial ball bearing 68 is strongly pressed against the bottom surface 614 of the annular recess 613.

  After that, when the lock nut 692 is tightened and the preload adjusting screw 69 is fixed to the right end of the motor case 61, the worm gear 66 and the rotary shaft 64 are moved in both the left and right directions of FIG. 6 by the deep radial ball bearing 68 and the sliding thrust bearing 673. A preload is applied to the thrust force, and there is no play. That is, the deep groove type radial ball bearing 68 and the sliding thrust bearing 673 for applying preload to the worm gear 66 and the rotating shaft 64 are arranged closer to the motor case 61 (electric motor 6 side) than the worm gear 66.

  In this state, even if the temperature of the electric motor 6 and the housing 65 changes, the motor case 61, the rotating shaft 64, and the worm gear 66 are formed of materials having substantially the same thermal expansion coefficient. There is no difference, and the preload applied to the worm gear 66 and the rotary shaft 64 is not increased or decreased by the deep groove radial ball bearing 68 and the sliding thrust bearing 673. Therefore, even if the temperature changes, an increase in load applied to the rotating shaft during operation of the electric motor can be suppressed, so that an increase in load current of the electric motor 6 can be suppressed.

  Next, a third embodiment of the present invention will be described. The third embodiment is a modification of the second embodiment, in which the worm gear 66 and the rotating shaft 64 are not molded integrally, but the worm gear 66 and the rotating shaft 64 are molded separately and then connected on the same axis. It is. In the following description, only structural portions and operations different from the above embodiment will be described, and redundant description will be omitted. Further, the same parts as those in the above embodiment will be described with the same numbers.

  FIG. 7 is a sectional view of the electric motor 6 according to the third embodiment of the present invention. As shown in FIG. 7, the rotating shaft 64 and the worm gear 66 are formed separately, and are coupled on the same axis by a coupling 643 so that rotational torque can be transmitted from the rotating shaft 64 to the worm gear 66. The motor case 61, the rotating shaft 64, and the worm gear 66 are formed of an iron-based material having substantially the same thermal expansion coefficient. The means for connecting the rotary shaft 64 and the worm gear 66 that are separately formed is not limited to the coupling 643, but may be any means capable of transmitting rotational torque, such as serrations, splines, and rubber couplings. .

  The left end of the rotating shaft 64 (near the position where the rotating shaft 64 is connected to the coupling 643) is pivotally supported by a deep groove radial ball bearing 68, and the outer periphery of the outer ring 682 of the deep groove radial ball bearing 68 is the embodiment. 2, the motor case 61 is fitted into an annular recess 613 formed in the flange portion 612. The left end surface of the outer ring 682 of the deep groove radial ball bearing 68 is in contact with the bottom surface 614 of the annular recess 613. The outer ring 682 of the deep groove radial ball bearing 68 and the annular recess 613 may be fitted to each other by an interference fit or a clearance fit.

  Further, the fitting of the outer periphery of the rotating shaft 64 and the inner periphery of the inner ring 681 of the deep groove radial ball bearing 68 may be an interference fit or a clearance fit. The deep groove radial ball bearing 68 supports the rotating shaft 64 inside the motor case 61. Further, similarly to the second embodiment, a step surface 642 is formed on the rotating shaft 64, and the step surface 642 is in contact with the right end surface of the inner ring 681 of the deep groove radial ball bearing 68.

  When the preload adjusting screw 69 is appropriately screwed and the rotating shaft 64 is pressed to the left via the sliding thrust bearing 673, the deep radial radial ball bearing 68 is pressed to the left by the step surface 642 of the rotating shaft 64, and the depth groove The left end surface of the outer ring 682 of the radial ball bearing 68 is strongly pressed against the bottom surface 614 of the annular recess 613.

  After that, when the lock nut 692 is tightened and the preload adjusting screw 69 is fixed to the right end of the motor case 61, the worm gear 66 and the rotary shaft 64 are moved in both the left and right directions of FIG. 7 by the deep radial ball bearing 68 and the sliding thrust bearing 673. A preload is applied to the thrust force, and there is no play. That is, the deep groove type radial ball bearing 68 and the sliding thrust bearing 673 for applying preload to the worm gear 66 and the rotating shaft 64 are arranged closer to the motor case 61 (electric motor 6 side) than the worm gear 66.

  In this state, even if the temperature of the electric motor 6 and the housing 65 changes, the motor case 61, the rotating shaft 64, and the worm gear 66 are formed of materials having substantially the same thermal expansion coefficient. There is no difference, and the preload applied to the worm gear 66 and the rotary shaft 64 is not increased or decreased by the deep groove radial ball bearing 68 and the sliding thrust bearing 673. Therefore, even if the temperature changes, an increase in load applied to the rotating shaft during operation of the electric motor can be suppressed, so that an increase in load current of the electric motor 6 can be suppressed.

  In the above embodiment, the magnet 62 is fixed to the inner peripheral surface 611 of the motor case 61 of the electric motor 6 and the armature 63 is attached to the rotating shaft, but the armature is attached to the inner peripheral surface 611 of the motor case 61. You may apply to the brushless motor which fixed and attached the magnet to the rotating shaft.

  In the above embodiment, it is preferable to employ the following structure because the worm gear 66 and the rotating shaft 64 can be prevented from swinging around the deep groove radial ball bearing 68. That is, a conical hole whose diameter increases toward the right side is formed in the axial center of the right end surface 641 of the rotating shaft 64, and the left end surface of the sliding thrust bearing 673 is engaged with the conical hole in a complementary manner. A conical or spherical protrusion is formed. That is, the contact shaft of the rotating shaft and the sliding bearing is concavo-convexly fitted. Alternatively, a preload is applied radially inward between the inner periphery of the right slide bearing 671 and the outer periphery of the rotary shaft 64 and between the inner periphery of the left slide bearing 672 and the outer periphery of the left end 661 of the worm gear 66. In other words, the rotation shaft 64 and the worm gear 66 can be moved in the axial direction without any radial play.

  Further, in the above-described embodiment, an example is shown in which the present invention is applied to a speed reduction mechanism composed of a worm gear and a worm wheel. . In the above embodiment, an example is shown in which the present invention is applied to a steering device that performs only one of telescopic position adjustment and tilt position adjustment. However, the present invention is applied to a steering device that can adjust both the telescopic position and tilt position. Also good.

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 the partial cross section which shows the electric tilt type steering apparatus of this invention. It is a principal part schematic block diagram including the partial cross section which shows the electric telescopic steering device of this invention. FIG. 4 is a bottom view of FIG. 3. It is sectional drawing of the electric motor of Example 1 of this invention. It is sectional drawing of the electric motor of Example 2 of this invention. It is sectional drawing of the electric motor of Example 3 of this invention. It is sectional drawing of the electric motor used for the conventional electric steering device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric steering device 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 portion 41B Lower shaft support portion 42 Outer column 43 Inner column 44A Front shaft support portion 44B Rear shaft Supporting portion 45 Opening portion 45A Front end 45B Rear end 51 Lower vehicle body mounting bracket 511 Mounting portion 512 Pivot portion 513 Pivot pin 52 Upper vehicle body mounting bracket 521 Mounting portion 522 Column support portion 522A Left end surface 53 Car body 6 Electric motor 61 Motor case 611 Inner peripheral surface 612 Flange portion 613 Annular recess 614 Bottom surface 62 Magnet 63 Armature 64 Rotating shaft 641 Right end surface 642 Differential surface 643 Coupling 65 Housing 651 Flange portion 652 Annular recess 653 Bottom surface 654 Annular recess 655 Bottom surface 66 Worm gear 661 Left end portion 662 Left end surface 671, 672 Slide bearing 673 Slide thrust bearing 674 Slide thrust bearing 68 Deep groove radial ball 1 Inner ring-shaped radial bearing 1 682 Outer ring 69 Preload adjusting screw 691 End face 692 Lock nut 71 Feed screw 72 Worm wheel 73 Nut 74 Ball 75 Sleeve 75A Inner circumference

Claims (8)

A steering shaft with a steering wheel mounted on the rear side of the vehicle body,
A column capable of pivotally supporting the steering shaft and adjusting a tilt position with a tilt center axis as a fulcrum or a telescopic position adjustment along the center axis of the steering shaft,
Electric motor,
A rotating shaft rotatably supported on the motor case of the electric motor,
In the electric steering apparatus comprising a housing coupled to the motor case, incorporating a speed reduction mechanism for decelerating the rotation of the rotating shaft and transmitting the tilt motion or telescopic motion of the column,
The rotating shaft of the electric motor and the input shaft of the speed reduction mechanism are formed on the same axis,
The electric steering device according to claim 1, wherein the rotary shaft and the input shaft are preloaded on both sides in the axial direction by a bearing provided closer to the electric motor than the input shaft. A steering shaft with a steering wheel mounted on the rear side of the vehicle body,
A column capable of pivotally supporting the steering shaft and adjusting a tilt position with a tilt center axis as a fulcrum or a telescopic position adjustment along the center axis of the steering shaft,
Electric motor,
A rotating shaft rotatably supported on the motor case of the electric motor,
In the electric steering apparatus comprising a housing coupled to the motor case, incorporating a speed reduction mechanism for decelerating the rotation of the rotating shaft and transmitting the tilt motion or telescopic motion of the column,
The rotating shaft of the electric motor and the input shaft of the speed reduction mechanism are formed on the same axis,
The rotating shaft is axially supported by bearings at both ends in the axial direction,
Of the bearings that support the rotating shaft, the bearing on the input shaft side supports the rotating shaft so that it cannot move in the axial direction,
Of the bearings that support the rotating shaft, the bearing on the side opposite to the input shaft supports the rotating shaft,
An electric steering device, wherein a preload is applied to an end of the rotating shaft on the side opposite to the input shaft toward the input shaft. In the electric steering device according to claim 1 or 2,
The electric steering apparatus, wherein an input shaft of the speed reduction mechanism has an end opposite to the electric motor supported on the housing of the speed reduction mechanism so as to be movable in the axial direction. In the electric steering device according to claim 1 or 2,
An electric steering apparatus, wherein the rotating shaft and the input shaft of the speed reduction mechanism are integrally formed. In the electric steering device according to claim 1 or 2,
The electric steering apparatus, wherein the rotating shaft and the input shaft of the speed reduction mechanism are formed separately and are connected to each other so as to transmit rotational torque from the rotating shaft to the input shaft of the speed reduction mechanism. In the electric steering device according to claim 1 or 2,
The electric steering apparatus according to claim 1, wherein the motor case and the rotary shaft of the electric motor are formed of a material having substantially the same thermal expansion coefficient. In the electric steering device according to claim 1 or 2,
A worm gear is formed on the input shaft, and a tilting motion or a telescopic motion is transmitted to the column via a worm wheel meshing with the worm gear. In the electric steering device according to any one of claims 3 to 6,
A worm gear is formed on the input shaft, and a tilting motion or a telescopic motion is transmitted to the column via a worm wheel meshing with the worm gear.

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