JP2014126192A - Coupling structure of rotary element and rotational shaft, and steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupling structure A of a rotary element and a rotational shaft, which even if slippage occurs, can stabilize fastening torque after the slippage.SOLUTION: An output shaft 13b (a rotational shaft) of a second steering shaft 3 is press-fitted into a fitting hole 26 of a core grid 22 (a rotary element) of a worm wheel 21. A first spline 28 formed in an outer periphery 13d of the output shaft 13b and a second spline 29 formed in an inner periphery 26a of the fitting hole 26 are engaged with each other. The first spline 28 and the second spline 29 cross with each other. The first spline 28 extends in a shaft direction X1, for example, and the second spline 29 is inclined to the shaft direction X1, for example.

Description

  The present invention relates to a coupling structure of a rotating element and a rotating shaft and a steering device.

Patent Documents 1 and 2 propose an electric power steering device in which the inner periphery of a worm wheel that is rotationally driven by an electric motor and the outer periphery of a steering shaft are serrated or splined.
In Patent Document 3, a composite gear in which a core metal as an insert is fixed to the inner periphery of a synthetic resin annular tooth portion of a worm wheel, and a spline tooth inclined with respect to the axial direction is provided on the outer periphery of the core metal. Proposed.

JP 2001-10515 A JP 2009-95122 A JP 2008-249071 A

  An excessive torque may be input to the coupling portion between the steering shaft and the fitting hole of the core metal of the worm wheel. In that case, in serration fitting (spline fitting) with axially extending serration teeth (spline teeth), once the fitting hole and the steering shaft slip, the core metal and the steering shaft are then fastened. The power varies and is not stable.

For example, when the mandrel and the steering shaft slide for the second time, if a twist or the like has occurred due to the first slip, the torque that causes the second slip increases. On the other hand, when the serration teeth are bent due to the first slip, the torque that causes the second slip becomes low.
Therefore, an object of the present invention is to provide a coupling structure of a rotating element and a rotating shaft that can stabilize the subsequent fastening torque even if slippage occurs, and a steering device including the same.

  In order to achieve the object, the invention of claim 1 includes a rotating element (22; 32; 49) having a fitting hole (26; 31; 55) and a rotating shaft (13; press-fitted into the fitting hole). 5), and the first spline (28; 280; 64) formed on the outer periphery (13d; 41a) of the rotating shaft and the inner periphery (26a; 31a; 55a) of the fitting hole. The second spline (29; 290; 65) provides a coupling structure (A; A1; A2) of the rotating element and the rotating shaft extending in a direction crossing each other.

In addition, although the alphanumeric character in a parenthesis represents the corresponding component etc. in embodiment mentioned later, this does not mean that this invention should be limited to those embodiment as a matter of course. The same applies hereinafter.
Further, as in claim 2, the first rotating element (32) as the rotating element having the first fitting hole (31) as the fitting hole, and the first rotating element being press-fitted into the first rotating element (32). A second rotating element (34) having two fitting holes (33), and a third spline (35) formed on the outer periphery (32a) of the first rotating element and the second fitting hole The fourth spline (36) formed on the circumference (33a) may extend in a direction intersecting with each other.

  Further, as in claim 3, when the transmission torque in the first rotation direction exceeds a predetermined value, slippage occurs on either the outer periphery of the first rotation element or the inner periphery of the first fitting hole. And when the transmission torque in the second rotational direction exceeds a predetermined value, the first spline and the first spline are configured to cause slippage on the other of the outer periphery of the first rotating element and the inner periphery of the first fitting hole. The fastening force with the second spline may differ depending on the rotational direction (Y1, Y2), and the fastening force between the third spline and the fourth spline may differ depending on the rotational direction.

  Further, as in claim 4, the inclination angles of a pair of tooth surfaces (281a, 281b; 291a, 291b) of at least one spline tooth (281, 291) of the first spline and the second spline are different from each other. The inclination angles of the pair of tooth surfaces (351a, 351b; 361a, 361b) of at least one spline tooth (351, 361) of the third spline and the fourth spline may be different from each other.

The invention of claim 5 is a steering device to which the coupling structure of the rotating element and the rotating shaft according to any one of claims 1 to 4 is applied, wherein the rotating element is an electric motor (19). There is provided a steering device (1) which is a metal core (22; 32) of a worm wheel (21) which is rotationally driven by the rotation shaft, and whose rotation shaft is a steering shaft (13).
Further, the invention of claim 6 is a steering device to which the coupling structure of the rotating element and the rotating shaft according to any one of claims 1 to 4 is applied, wherein the rotating element is a universal joint yoke (49). And the rotating shaft is an intermediate shaft (5) including a fixing portion (63) fixed by welding to the peripheral edge (58a) of the opening (58) of the fitting hole (55). (1B) is provided.

According to the first aspect of the present invention, when slip occurs between the rotating element and the rotating shaft due to the input of excessive torque, the first spline and the second spline are relatively displaced, and the teeth of each other are still Intersect at a new intersection where no slip has occurred. Therefore, it is possible to stably secure the fastening force between the rotating element and the rotating shaft even after the slip once occurs.
According to the second aspect of the present invention, it is excessive whether the slip is generated between the rotating shaft and the first fitting hole or between the first rotating element and the second fitting hole. It becomes possible to use properly according to the rotational direction in which a large transmission torque is inputted.

Specifically, it can be realized by changing the fastening force between the splines engaged with each other according to the rotation direction as in the third aspect.
More specifically, the fastening force can be varied according to the rotational direction by varying the inclination angle of at least one of the pair of spline teeth engaged with each other as in claim 4.

According to the fifth aspect of the present invention, in the steering device that applies the steering assisting force to the steering shaft by the electric motor, a slip occurs between the core metal of the worm wheel as the rotating element and the steering shaft as the rotating shaft. As a result, the subsequent fastening force between the worm and the steering shaft can be secured stably.
According to a sixth aspect of the present invention, in the steering device, the fixing portion by welding of the intermediate shaft as the rotating shaft with respect to the universal joint yoke as the rotating element is broken to form a gap between the intermediate shaft and the universal joint yoke. In addition, even after slipping once, the fastening force between the intermediate shaft and the universal joint yoke can be stably secured.

1 is a schematic diagram of an electric power steering apparatus in which a coupling structure between a rotating element and a rotating shaft according to an embodiment of the present invention is applied to a coupling structure between a worm wheel and a steering shaft. It is sectional drawing of a worm reduction gear. (A) is sectional drawing of a 1st spline tooth, (b) is sectional drawing of a 2nd spline tooth. It is a schematic diagram explaining the displacement of the crossing part of the 1st spline tooth of the 1st spline and the 2nd spline tooth, (a) shows the state before slip occurrence, and (b) shows the state after slip occurrence. ing. FIG. 5 is an exploded cross-sectional view of a worm wheel and a steering shaft to which a coupling structure between a rotating element and a rotating shaft according to another embodiment of the present invention is applied. (A) is sectional drawing of a 1st spline tooth, (b) is sectional drawing of a 2nd spline tooth. (A) is sectional drawing of a 3rd spline tooth, (b) is sectional drawing of a 4th spline tooth. FIG. 6 is a side view of a main part of a steering apparatus in which a coupling structure between a rotating element and a rotating shaft according to another embodiment of the present invention is applied to a coupling structure between a universal joint yoke and an intermediate shaft. It is sectional drawing of the coupling structure of FIG.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view of an electric power steering apparatus 1 to which a coupling structure A between a rotating element and a rotating shaft according to an embodiment of the present invention is applied. Referring to FIG. 1, an electric power steering apparatus 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, and an intermediate shaft 5 And a rack shaft 8 as a steered shaft having a rack 8a meshing with the pinion 7a provided in the vicinity of the end of the pinion shaft 7.

A steering mechanism 9 is constituted by a rack and pinion mechanism including a pinion shaft 7 and a rack shaft 8. Each end of the rack shaft 8 in the axial direction is connected to a corresponding steered wheel 11 via a corresponding tie rod 10 and a corresponding knuckle arm (not shown).
The rotation of the steering member 2 is transmitted to the steering mechanism 9 via the steering shaft 4 and the intermediate shaft 5. The rotation transmitted to the steering mechanism 9 is converted into an axial movement of the rack shaft 8. Thereby, the steered wheel 11 is steered.

  The steering shaft 3 includes a first steering shaft 12 connected to the steering member 2 and a second steering shaft 13 connected to the steering mechanism via the intermediate shaft 5. The second steering shaft 13 includes an input shaft 13a coupled to the first steering shaft 12 so as to be integrally rotatable, an output shaft 13b coupled to the steering mechanism 9 via the intermediate shaft 5, an input shaft 13a, and an output shaft. 13b is provided with a torsion bar 13c.

A cylindrical steering column SC that supports the steering shaft 4 is connected to a cylindrical jacket 14, a sensor housing 16 that houses a torque sensor 15 connected to one end of the jacket 14, and one end of the sensor housing 16. And a gear housing 18 in which the reduction gear 17 is accommodated.
The worm speed reducer 17 accommodated in the gear housing 18 is a speed reducer that decelerates the output rotation of the electric motor 19 that generates the steering assist force. The worm speed reducer 17 includes a worm 20 as a drive gear that is rotationally driven by an electric motor 19, and a worm wheel 21 as a driven gear that meshes with the worm 20.

  The worm wheel 21 is connected to an intermediate portion in the axial direction of the output shaft 13b of the second steering shaft 13 so as to be integrally rotatable and impossible in the axial direction. The worm wheel 21 includes an annular cored bar 22 as a rotating element coupled to the output shaft 13b so as to be integrally rotatable, and a synthetic resin member 23 that surrounds the cored bar 22 and forms teeth 23a on the outer peripheral surface portion. ing. The cored bar 22 is inserted into a mold when the synthetic resin member 23 is molded, for example, and the cored bar 22 and the molded synthetic resin member 23 are coupled so as to be integrally rotatable.

The output shaft 13b is rotatably supported by a pair of bearings 24 and 25, for example, which are rolling bearings such as ball bearings, which are arranged with the worm wheel 21 sandwiched in the axial direction. The bearing 24 is held by the sensor housing 16, and the bearing 25 is held by the gear housing 18.
In the present embodiment, the coupling structure A of the rotating element and the rotating shaft is applied to the connecting structure of the core metal 22 (rotating element) of the worm wheel 21 and the output shaft 13b (rotating shaft) of the second steering shaft 13. Yes. The cored bar 22 of the worm wheel 21 as a rotating element is provided with a fitting hole 26. The output shaft 13 b of the second steering shaft 13 has a press-fit portion 27 that is press-fit into the fitting hole 26.

As shown in FIG. 2, which is an exploded sectional view, a first spline 28 formed on the outer periphery 13 d of the output shaft 13 b of the second steering shaft 13 and a second spline 29 formed on the inner periphery 26 a of the fitting hole 26. And extend in directions crossing each other.
Specifically, one of the first spline 28 and the second spline 29 extends in the axial direction X1, and the other of the first spline 28 and the second spline 29 is inclined with respect to the axial direction X1. FIG. 2 shows an example in which the first spline 28 extends in the axial direction X1 and the second spline 29 is inclined with respect to the axial direction X1. In addition, as long as the 1st spline 28 and the 2nd spline 29 are extended in the direction which mutually cross | intersects, both the 1st spline 28 and the 2nd spline 29 may incline with respect to the axial direction X1.

As shown in FIG. 3A, the inclination angles of the pair of tooth surfaces 281a and 281b of the first spline teeth 281 of the first spline 28 are equal to each other. As shown in FIG. 3B, the inclination angles of the pair of tooth surfaces 291a and 291b of the second spline teeth 291 of the second spline 29 are equal to each other.
According to the present embodiment, when slip occurs between the cored bar 22 (rotating element) of the worm wheel 21 and the output shaft 13b (rotating shaft) of the second steering shaft 13 due to excessive torque input, Along with the slip, the first spline 28 on the inner periphery of the fitting hole 26 of the metal core 22 and the second spline 29 on the outer periphery of the output shaft 13b of the second steering shaft 13 are relatively displaced, and the spline teeth 281 291 crosses at a new intersection where no slip has occurred yet. Therefore, even after the slip once occurs, the fastening force (fastening torque) between the metal core 22 (rotating element) of the worm wheel 21 and the output shaft 13b (rotating shaft) of the second steering shaft 13 is stably secured. Thus, it is possible to realize the coupling structure A of the rotating element and the rotating shaft and the steering device 1.

  Specifically, as shown in FIG. 4A, which is a schematic diagram, in a state before slippage occurs between the output shaft 13 b of the second steering shaft 13 and the cored bar 22, The intersections of the first spline teeth 281, 282, 283, 284 and the second spline teeth 291, 292, 293, 294 of the second spline 29 are defined as P 1, P 2, P 3, P 4, respectively.

The first spline teeth 282 to 284 have the same configuration as the first spline teeth 281, but are given different reference numerals from the first spline 281 for easy understanding. The second spline teeth 292 to 294 have the same configuration as that of the second spline teeth 291, but are given different reference numerals from the second spline 291 for easy understanding.
When a slip (for example, a slip in which the cored bar 22 rotates in the first rotation direction Y1 with respect to the output shaft 13b of the second steering shaft 13) occurs due to an input of excessive torque, the intersections P1 to P4 are As shown in FIG.4 (b), it changes to a new position, updating each part which forms each cross | intersection part P1-P4. Thus, since it is updated to new intersections P1 to P4 that have not yet slipped, the fastening torque after the occurrence of slipping can be stabilized.

  Next, FIG. 5 is an exploded sectional view of a coupling structure A1 of a rotating element and a rotating shaft according to another embodiment of the present invention. Referring to FIG. 5, the present embodiment differs from the embodiment of FIG. 2 in that, in this embodiment, the first fitting hole 31 into which the worm wheel 30 is press-fitted with the output shaft 13 b of the second steering shaft 13. A first cored bar 32 as a first rotating element having a first cored bar 32, a second cored bar 34 as a second rotating element having a second fitting hole 33 into which the first cored bar 32 is press-fitted, and a first cored bar 32. And a synthetic resin member 23 formed by inserting the second cored bar 34. That is, the cored bar is composed of two pieces, a first cored bar 32 and a second cored bar 34.

A first spline 280 formed on the outer periphery 13d of the output shaft 13b of the second steering shaft 13 and a second spline 290 formed on the inner periphery 31a of the first fitting hole 31 extend in directions intersecting each other. Yes.
One of the first spline 280 and the second spline 290 extends in the axial direction X1, and the other of the first spline 280 and the second spline 290 is inclined with respect to the axial direction X1. FIG. 5 shows an example in which the first spline 280 extends in the axial direction X1 and the second spline 290 is inclined with respect to the axial direction X1. In addition, as long as the 1st spline 280 and the 2nd spline 290 are extended in the direction which mutually cross | intersects, both the 1st spline 280 and the 2nd spline 290 may incline with respect to the axial direction X1.

Further, the third spline 35 formed on the outer periphery 32a of the first cored bar 32 and the fourth spline 36 formed on the inner periphery 33a of the second fitting hole 33 of the second cored bar 34 intersect each other. Extending in the direction.
One of the third spline 35 and the fourth spline 36 extends in the axial direction X1, and the other of the third spline 35 and the fourth spline 36 is inclined with respect to the axial direction X1. FIG. 5 shows an example in which the third spline 35 extends in the axial direction X1 and the fourth spline 36 is inclined with respect to the axial direction X1. In addition, as long as the 3rd spline 35 and the 4th spline 36 are extended in the direction which mutually cross | intersects, both the 3rd spline 35 and the 4th spline 36 may incline with respect to the axial direction X1.

  As shown in FIG. 6A, the inclination angles of the pair of tooth surfaces 281a and 281b of the first spline teeth 281 of the first spline 280 are equal to each other. As shown in FIG. 6B, of the pair of tooth surfaces 291a and 291b of the second spline teeth 291 of the second spline 290, the inclination angle of the tooth surface 291a on the first rotation direction Y1 side is the second rotation direction. The inclination angle of the tooth surface 291b on the Y2 side is made larger.

  On the other hand, as shown in FIG. 7A, the inclination angles of the pair of tooth surfaces 351a and 351b of the third spline teeth 351 of the third spline 35 are equal to each other. As shown in FIG. 7B, of the pair of tooth surfaces 361a and 361b of the fourth spline teeth 361 of the fourth spline 36, the inclination angle of the tooth surface 361a on the first rotation direction Y1 side is the second rotation direction. It is made smaller than the inclination angle of the tooth surface 361b on the Y2 side.

  According to this embodiment, between the output shaft 13b (rotary shaft) of the second steering shaft 13 and the first fitting hole 31 of the first cored bar 32 (first rotating element), or the first cored bar 32 ( The direction of rotation in which excessive torque is input (first rotation) determines whether slippage occurs between the first rotation element) and the second fitting hole 33 of the second metal core 34 (second rotation element). Depending on the rotational direction Y1, the second rotational direction Y2), it can be used properly.

Specifically, the fastening force between the first spline 28 and the second spline 29 that are engaged with each other is made different according to the rotational directions Y1 and Y2, and the third spline 35 and the fourth spline that are engaged with each other. This can be realized by making the fastening force between the two different depending on the rotational directions Y1 and Y2.
More specifically, at least one pair of tooth surfaces of the first spline teeth 281 and the second spline teeth 291 that engage with each other (in the example of FIG. 6, the pair of tooth surfaces 291a and 291b of the second spline teeth 291). ) Can be varied according to the rotational directions Y1 and Y2. In addition, the inclination angle of at least one pair of tooth surfaces of the third spline teeth 351 and the fourth spline teeth 361 that engage with each other (the pair of tooth surfaces 361a and 361b of the fourth spline teeth 361 in the example of FIG. 7). By making different from each other, the fastening force can be made different according to the rotation directions Y1 and Y2.

  The connecting structure A of the rotating element and the rotating shaft in the embodiment is used for connecting the core metal 22 of the worm wheel 21 and the steering shaft 3 (the output shaft 13b of the second steering shaft 13). On the other hand, the coupling structure A2 of the rotating element and the rotating shaft of the electric power steering apparatus 1B of another embodiment shown in FIG. 8 is a coupling structure of the universal joint yoke 49 and the intermediate shaft 5X (the shaft 41). Has been applied.

Referring to FIG. 8, intermediate shaft 5X (corresponding to intermediate shaft 5 in FIG. 1) slides along shaft direction Z1 with shaft 41 constituting the lower shaft and sleeve 42 constituting the upper shaft, for example. It is formed by spline fitting so that it can move and transmit torque.
The shaft 41 has one end 411 (a lower end in the axial direction), and the one end 411 is connected to the universal joint 6. The sleeve 42 has one end 421 (an upper end in the axial direction), and the one end 421 is connected to the universal joint 4.

  The universal joint 4 includes a pair of universal joint yokes 43 and 44 and a cross shaft 45 connecting the pair of universal joint yokes 43 and 44. One universal joint yoke 43 is fixed so as to be integrally rotatable with the output shaft 13 b of the second steering shaft 13. The other universal joint yoke 44 (corresponding to the second universal joint yoke) has a pair of arms 46 and 47 to which a corresponding pair of trunnions of the cross shaft 45 are connected and a U-shape between the pair of arms 46 and 47. And a connecting portion 48 to be connected. The connecting portion 48 is fixed to the one end 421 of the sleeve 42 of the intermediate shaft 5X so as to be integrally rotatable, for example, by welding.

  The universal joint 6 includes a pair of universal joint yokes 49 and 50 and a cross shaft 51 that connects the pair of universal joint yokes 49 and 50. One universal joint yoke 49 includes a pair of arms 52 and 53 to which a corresponding pair of trunnions of the cross shaft 51 are connected, and a connecting portion 54 that connects the pair of arms 52 and 53 in a U shape. Yes. The connecting portion 54 is fixed to one end 411 of the shaft 41 of the intermediate shaft 5X so as to be integrally rotatable. The other universal joint yoke 50 is fixed to one end of the pinion shaft 7 so as to be integrally rotatable.

  Referring to FIG. 9 which is an enlarged cross-sectional view of the coupling structure A2, a connection for connecting the base ends of the pair of arms 52, 53 of the universal joint yoke 49 to which the shaft 41 of the intermediate shaft 5X is connected in a U shape. The portion 54 is formed with a fitting hole 55 through which the shaft 41 is inserted. An end surface 54a of the connecting portion 54 forms an annular recess 56 that faces the cross shaft 51 side. The fitting hole 55 has a first opening 57 that opens to the bottom of the annular recess 56, and a second opening 58 that opens to the opposite side of the first opening 57.

  The shaft 41 of the intermediate shaft 5X is inserted into the fitting hole 55 and protrudes from the first opening 57, and extends radially outward from the distal end 59 to the periphery of the first opening 57 and the axial direction Z1. Are provided with an outward projection 60 for retaining against each other with a gap. The shaft 41 has a press-fit portion 61 disposed in the fitting hole 55 adjacent to the front end portion 59, and a peripheral edge 58 a of the second opening 58 of the fitting hole 55 adjacent to the press-fit portion 61 via the welded portion 62. And a fixed portion 63 fixed thereto.

A first spline 64 formed on the outer periphery 41a of the shaft 41 of the intermediate shaft 5X and a second spline 65 formed on the inner periphery 55a of the fitting hole 55 extend in a direction intersecting with each other.
Specifically, one of the first spline 64 and the second spline 65 extends in the axial direction Z1, and the other of the first spline 64 and the second spline 65 is inclined with respect to the axial direction Z1. FIG. 9 shows an example in which the first spline 64 extends in the axial direction Z1 and the second spline 65 is inclined with respect to the axial direction Z1. In addition, as long as the 1st spline 64 and the 2nd spline 65 are extended in the direction which mutually cross | intersects, both the 1st spline 64 and the 2nd spline 65 may incline with respect to the axial direction Z1.

  According to the present embodiment, the fixing portion 63 by welding of the intermediate shaft 5X (the shaft 41) as the rotating shaft with respect to the universal joint yoke 49 as the rotating element is broken, so that the intermediate shaft 5X and the universal joint yoke are broken. 49, the fastening force between the intermediate shaft 5X and the universal joint yoke 49 can be stably secured even after slippage occurs once.

  Although not shown, as an example of a modification of the embodiment of FIG. 9, an intermediate shaft as a rotation shaft is press-fitted into a first fitting hole of a sleeve as a first rotation element, and the sleeve is inserted into the second rotation element. And press fit into the second fitting hole of the universal joint yoke, either between the intermediate shaft and the first fitting hole of the sleeve, or between the sleeve and the second fitting hole of the universal joint yoke. You may make it use properly according to the rotation direction into which excessive torque is input whether slip is generated.

  The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1,1B ... Electric power steering apparatus, 2 ... Steering member, 3 ... Steering shaft, 5X ... Intermediate shaft (rotary shaft), 9 ... Steering mechanism, 13 ... Second steering shaft (rotating shaft), 13b ... Output shaft ( Rotating shaft), 13d ... outer periphery, 19 ... electric motor, 20 ... worm, 21 ... worm wheel, 22 ... cored bar (rotating element), 23 ... synthetic resin member, 26 ... fitting hole, 26a ... inner periphery, 28; 280 ... 1st spline, 281-284 ... 1st spline tooth, 281a, 281b ... tooth surface, 29; 290 ... 2nd spline, 291-294 ... 2nd spline tooth, 291a, 291b ... tooth surface, 30 ... worm wheel 31 ... 1st fitting hole, 31a ... inner circumference, 32 ... 1st metal core (1st rotation element), 32a ... outer periphery, 33 ... 2nd fitting hole, 33a ... Circumference 34 ... second metal core (second rotating element) 35 ... third spline 351 ... third spline tooth 351a, 351b ... tooth surface 36 ... fourth spline 361 ... fourth spline tooth 361a, 361b ... tooth surface, 41 ... shaft (rotating shaft), 41a ... outer periphery, 49 ... universal joint yoke (rotating element), 52, 53 ... arm, 54 ... connecting portion, 55 ... fitting hole, 55a ... inner periphery, 58 ... second opening, 58a ... periphery, 61 ... press-fit portion, 62 ... welded portion, 63 ... fixed portion, 64 ... first spline, 65 ... second spline, A; A1; A2 ... coupling of rotating element and rotating shaft Structure, P1 to P4 ... intersection, X1 ... axial direction (of the steering shaft), Y1 ... first rotation direction, Y2 ... second rotation direction, Z1 ... axial direction (intermediate shaft)

Claims (6)

A rotating element having a fitting hole;
A rotating shaft press-fitted into the fitting hole,
A coupling structure of a rotating element and a rotating shaft, wherein a first spline formed on the outer periphery of the rotating shaft and a second spline formed on the inner periphery of the fitting hole extend in directions intersecting each other. The first rotating element as the rotating element according to claim 1, wherein the rotating element has a first fitting hole as the fitting hole.
A second rotating element having a second fitting hole into which the first rotating element is press-fitted, and
A rotating element and a rotating shaft extending in a direction in which a third spline formed on the outer periphery of the first rotating element and a fourth spline formed on the inner periphery of the second fitting hole intersect each other. Bond structure.   In Claim 2, when the transmission torque in the first rotation direction exceeds a predetermined value, slip occurs on either the outer periphery of the first rotation element and the inner periphery of the first fitting hole, When the transmission torque in the rotational direction exceeds a predetermined value, the first spline and the second spline are configured to cause slippage on the other of the outer periphery of the first rotating element and the inner periphery of the first fitting hole. The coupling structure of the rotating element and the rotation shaft is different in that the fastening force between the third spline and the fourth spline is different according to the rotation direction. In Claim 3, the inclination angle of a pair of tooth surfaces of at least one spline tooth of the first spline and the second spline is different from each other,
A coupling structure of a rotating element and a rotating shaft, wherein the inclination angles of a pair of tooth surfaces of at least one of the third spline and the fourth spline are different from each other. A steering device to which the coupling structure of the rotating element and the rotating shaft according to any one of claims 1 to 4 is applied,
The rotating element is a core metal of a worm wheel that is driven to rotate by an electric motor,
A steering device, wherein the rotating shaft is a steering shaft. A steering device to which the coupling structure of the rotating element and the rotating shaft according to any one of claims 1 to 4 is applied,
The rotating element is a universal joint yoke;
The steering device, wherein the rotation shaft is an intermediate shaft including a fixing portion fixed to the periphery of the opening of the fitting hole by welding.

Images