JP7132778B2 - steering device - Google Patents

Description

The present invention relates to steering devices.

Patent Document 1 describes a power steering device that transmits the torque of an electric motor to a nut via an input pulley, a belt and an output pulley to axially drive a rack bar.

JP 2017-159863 A

In the technique described in Patent Document 1, the nut that constitutes a part of the ball screw mechanism is supported by a single ball bearing, which is a so-called cantilever structure. Friction was generated in the screw part and ball bearings, and there was a risk that torque transmission loss and steering feeling would deteriorate.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a steering apparatus that reduces torque transmission loss and improves steering feel.

In order to achieve the above object, according to a preferred aspect of the present invention, a so-called double-support structure is adopted in which the nut is supported on both sides in the axial direction.

Therefore, according to a preferred aspect of the present invention, torque transmission loss can be reduced and steering feeling can be improved.

FIG. 2 is a view of the power steering device of Embodiment 1 as seen from the rear side of the vehicle; FIG. 2 is a partial cross-sectional view of FIG. 1; FIG. 8 is a partial cross-sectional view of Embodiment 2; FIG. 11 is a partial cross-sectional view of Embodiment 3; FIG. 12 is a partial cross-sectional view of Embodiment 4;

[Embodiment 1]
1 is a view of the power steering device of Embodiment 1 as seen from the vehicle rear side, and FIG. 2 is a partial cross-sectional view of FIG.

A power steering device 1 which is a steering device to which the present invention is applied has a steering mechanism 2 and an assist mechanism 3 . The steering mechanism 2 transmits the rotation of a steering wheel (not shown) rotated by the driver to a rack bar (steering shaft) 4 for steering the front wheels (steering wheels).
The steering mechanism 2 has a steering shaft 2 a connected to the steering wheel and a pinion shaft (not shown) that meshes with the rack of the rack bar 4 .
The steering shaft 2a and the pinion shaft are connected by a torsion bar. The assist mechanism 3 applies an assist force to the rack bar 4 to reduce the steering load on the driver.
The housing 5 includes a housing body portion 20 , a reduction gear housing space 21 , a first bearing holding portion 22 and a second bearing holding portion 23 .
The housing body 20 has a first housing 20a and a second housing 20b combined with the first housing 20a.
The steering mechanism 2 and the assist mechanism 3 are housed inside a housing body 20 having a first housing 20a and a second housing 20b.
The housing main body 20 accommodates the rack bar 4 so as to be movable in the direction of the rotation axis P of the rack bar 4 .
A speed reducer housing space 21 for housing a speed reducer, which will be described later, is formed by forming large diameter portions of the first housing 20a and the second housing 20b of the housing main body 20, and a space is formed by abutting and fixing them to each other. ing.
The assist mechanism 3 has an electric motor 6 and a ball screw mechanism 7 . The output of the electric motor 6 is controlled by a controller (not shown) according to the torsion bar torque (steering torque), vehicle speed, and the like. The ball screw mechanism 7 converts the rotary motion of the electric motor 6 into linear motion and transmits it to the rack bar 4 .
The output of the electric motor 6 is transmitted to the ball screw mechanism 7 via a reduction gear.
The speed reducer includes a tubular electric motor side pulley 11 fixed to the drive shaft 6a of the electric motor 6, a nut side pulley 9 fixed to the nut 8, and an endless belt 12 wound around both the pulleys 9 and 11. consists of
The outer diameter of the nut side pulley 9 is formed larger than the outer diameter of the electric motor side pulley 11 . Therefore, the electric motor side pulley 11 , the endless belt 12 and the nut side pulley 9 function as a speed reducer for the electric motor 6 .
The electric motor-side pulley 11 , the endless belt 12 and the nut-side pulley 9 are housed inside the speed reducer housing space 21 .
The nut-side pulley 9 is composed of a nut-side pulley cylindrical portion 9c and a nut-side pulley boss portion 9d.
The electric motor side pulley 11 has an electric motor side pulley belt winding portion 11a, and the electric motor side pulley belt winding portion 11a has a cylindrical shape.
A nut-side pulley belt winding portion 9b is provided radially outward of the nut-side pulley cylindrical portion 9c with respect to the rotation axis P of the nut 8 .
The nut-side pulley boss portion 9d extends continuously inward in the radial direction from the left end of the nut-side pulley tubular portion 9c so as to face the nut 8 in the direction of the rotation axis P of the nut 8. , a plurality of screw through-holes 9a as nut-side pulley fixing portions.
Similarly, the nut 8 has a plurality of screw female threads 8e that open at positions facing the plurality of screw through-holes 9a.
Before being connected to the nut 8 , the nut-side pulley 9 can move relative to the nut 8 in the radial direction about the rotation axis P of the nut 8 .
Therefore, since the relative positions of the axial centers of the nut 8 and the nut-side pulley 9 can be adjusted before the nut 8 and the nut-side pulley 9 are connected by the plurality of screws 10, the nut 8 and the nut-side pulley 9 can be adjusted. coaxiality can be increased.
The plurality of screws 10 are coupled to the plurality of screw female thread portions 8e via the plurality of screw through holes 9a, thereby integrally connecting the nut 8 and the nut-side pulley 9 so that they partially overlap. ing.

The nut 8 is made of metal and has a cylindrical shape surrounding the rack bar 4 .
The nut 8 is rotatably supported on the housing main body 20 of the housing 5 by a first ball bearing 30 as a first bearing and a second ball bearing 31 as a second bearing.
The first ball bearing 30 is composed of a first outer race 30a, a first inner race 30b, and a plurality of first balls 30c.
The second ball bearing 31 is composed of a second outer race 31a, a second inner race 31b, and a plurality of second balls 31c.
In addition, in the direction of the rotation axis P of the nut 8, the first ball bearing 30 is arranged so that a plurality of balls 16, which will be described later, are disposed on one end side of the ball circulation groove 15 formed by the nut ball screw groove 8b and the rack bar ball screw groove 4b. It is provided at a position closer to the first end 21a of the reducer housing space 21 than the ball circulation range a of the tube 70 that has the function of circulating from the ball to the other end.
In addition, the second ball bearing 31 moves a plurality of balls 16 (to be described later) in the direction of the rotation axis P of the nut 8 to one end side of the ball circulation groove 15 formed by the nut ball screw groove 8b and the rack bar ball screw groove 4b. It is provided at a position closer to the speed reducer housing space second end 21b of the speed reducer housing space 21 than the ball circulation range a of the tube 70 that has the function of circulating from the ball to the other end side.
As a result, a sufficient support span between the first ball bearing 30 and the second ball bearing 31 can be ensured, and tilting of the nut 8 can be further suppressed.
Further, the nut-side pulley belt winding portion 9b is positioned closer to the endless belt 12 than the distance b between the center of the plurality of first balls 30c and the point O that bisects the endless belt 12 in the direction of the rotation axis P of the nut 8. , and the distance c between the center of the plurality of second balls 31c and the point O that bisects the .
As a result, the nut-side pulley 9 is supported by a so-called cantilever structure with respect to the nut 8, so that the moment arm, which is the distance from the first ball bearing 30, which is the support point of the nut-side pulley 9, to the endless belt 12 is As the length increases, the nut-side pulley 9 tilts more due to the tensile force of the endless belt 12. However, by providing the nut-side pulley belt winding portion 9b at the position described above, the moment arm can be shortened. can be suppressed, and the occurrence of vibration in the speed reducer can be suppressed.
The first ball bearing 30 supports the nut 8 via the nut-side pulley 9 in a region including the first end 8c of the nut 8, and the second ball bearing 31 includes the second end 8d of the nut 8. It directly supports the nut 8 in the area.
Since the first ball bearing 30 supports the nut 8 via the nut-side pulley 9 in this way, the degree of freedom in layout can be improved.
The first outer race 30a of the first ball bearing 30 is directly fixed to the first bearing holding portion 22 of the first housing 20a by press fitting. A second large diameter portion 23a having a third inner diameter and a second small diameter portion 23a having a fourth inner diameter smaller than the third inner diameter of the second bearing holding portion 23 of the second housing 20b through a pair of second spring washers 43. Between the stepped portion 23c between the portions 23b and the second locknut 41, it is directly fixed to and held by the second bearing holding portion 23 of the second housing 20b.
Since the first ball bearing 30 and the second ball bearing 31 are provided in the separate first housing 20a and the second housing 20b, respectively,
Since it is possible to improve the layout flexibility of the position of the nut 8 of each of the first ball bearing 30 and the second ball bearing 31 in the direction of the rotation axis P, the distance between the first ball bearing 30 and the second ball bearing 31 can be compared. It is also possible to take a target length, and the support span of the nut 8 becomes long, and the tilting of the nut can be further suppressed.
In addition, since the second outer race 31a of the second ball bearing 31 is directly fixed to the second bearing holding portion 23 via the pair of second spring washers 43, vibrations of the second ball bearing 31 and the nut 8 are suppressed. can be suppressed.
In addition, inside the first inner race 30b, the left-hand end portion of the nut-side pulley cylindrical portion 9c of the nut-side pulley 9 is inserted (press-fitted), and inside the second inner race 31b, a nut 8 is inserted (press-fitted) in the drawing to the right.
A tapered portion 60 is formed at the outer peripheral end (leftward in the drawing) of the nut-side pulley cylindrical portion 9c of the nut-side pulley 9 in the direction of insertion into the first inner race 30b of the first ball bearing 30. .
Therefore, since the nut-side pulley 9 is inserted into the first inner race 30b along the tapered portion 60, the assembling workability can be improved.
The first outer race 30a and the second outer race 31a are fixed to the first housing 20a and the second housing 20b, respectively, and the nut 8 and the nut-side pulley 9 are assembled to the first inner race 30b and the second inner race 31. In this case, by inserting, the assembling work can be performed even in the closed state between the first housing 20a and the second housing 20b.
Further, since the first ball bearing 30 is provided on the outer circumference of the nut-side pulley 9, the inner diameter of the first ball bearing 30 is larger than the inner diameter of the second ball bearing 31, so the diameter of the plurality of first balls 30c is It is smaller than the diameter of the plurality of second balls 31c.
As a result, it is possible to suppress an increase in the size of the first ball bearing 30 and, in turn, an increase in the size of the entire device.
Furthermore, since the inner diameter of the second ball bearing 31 can be made smaller than that of the first ball bearing 30, the diameter of the plurality of second balls 31c can be increased accordingly, and sufficient bearing capacity can be secured. .
The first ball bearing 30 and the second ball bearing 31 may be supported by the first housing 20a and the second housing 20b via another member.

The nut 8 has a nut main body portion 8a and a nut ball screw groove 8b formed in the inner circumference of the nut body portion 8a.
On the other hand, a spiral groove-shaped rack bar ball screw groove (steering shaft ball screw groove) 4b is formed on the outer periphery of a rack bar main body portion (steering shaft main body portion) 4a of the bar-shaped rack bar 4 . A ball circulation groove 15 is formed by the nut ball screw groove 8b and the rack bar ball screw groove 4b. A plurality of metal balls 16 are filled in the ball circulation groove 15 . In the ball screw mechanism 7 , the rack bar 4 moves axially with respect to the nut 8 as the balls 16 move in the ball circulation groove 15 as the nut 8 rotates.
The synthetic resin tube 70 has a function of circulating the plurality of balls 16 from one end side of the ball circulation groove 15 to the other end side.

Next, functions and effects will be described.
The steering device of the first embodiment has the following effects.

(1) The nut 8 is supported inside the housing body 20 on both sides in the direction of the rotation axis P, which is a so-called double-end structure.
Therefore, the inclination of the nut 8 with respect to the rack bar 4 can be suppressed, and the friction between the ball screw mechanism 7 and the first ball bearing 30 and the second ball bearing 31 can be reduced. Feeling can be improved.

(2) The second outer race 31a of the second ball bearing 31 has the third inner diameter of the second bearing holding portion 23 of the second housing 20b through the pair of second spring washers 43 by the second locknut 41. Between the stepped portion 23c between the second large-diameter portion 23a and the second small-diameter portion 23b having a fourth inner diameter smaller than the third inner diameter and the second locknut 41, the second bearing holding portion of the second housing 20b 23 to be directly fixed and held.
Therefore, it is possible to prevent the second outer race 31a of the second ball bearing 31 from coming off or shifting, and to prevent the second ball bearing 31 and the nut 8 from vibrating.

(3) The nut 8 and the nut-side pulley 9 are partially overlapped, and the first ball bearing 30 supports the nut 8 via the nut-side pulley 9 .
Therefore, it is possible to improve the degree of freedom of layout.

(4) Before being connected to the nut 8, the nut-side pulley 9 is movable relative to the nut 8 in the radial direction about the rotation axis P of the nut 8, and the plurality of screws 10 are arranged in the plurality of screw through holes. The nut 8 and the nut-side pulley 9 are integrally connected so as to partially overlap each other by coupling with a plurality of screw female thread portions 8e via 9a.
Therefore, since the relative positions of the axial centers of the nut 8 and the nut-side pulley 9 can be adjusted by the plurality of screws 10 before the nut 8 and the nut-side pulley 9 are connected, degree can be increased.

(5) The first ball bearing 30 is provided on the outer circumference of the nut-side pulley 9, and the inner diameter of the first ball bearing 30 is larger than the inner diameter of the second ball bearing 31. Therefore, the diameter of the plurality of first balls 30c is It is made smaller than the diameter of the plurality of second balls 31c.
Therefore, it is possible to suppress an increase in the size of the first ball bearing 30 and, in turn, an increase in the size of the entire device. Furthermore, since the inner diameter of the second ball bearing 31 can be made smaller than that of the first ball bearing 30, the diameter of the plurality of second balls 31c can be increased accordingly, and sufficient bearing capacity can be secured. .

(6) The first ball bearing 30 and the second ball bearing 31 are arranged in the direction of the rotation axis P of the nut 8 so that the plurality of balls 16 are formed by the nut ball screw groove 8b and the rack bar ball screw groove 4b. From the ball circulation range a of the tube 70 that has the function of circulating from one end side of the circulation groove 15 to the other end side, the first end 21a of the reduction gear housing space 21 and the second end 21a of the reduction gear housing space It is provided at a position close to the second end 21b.
Therefore, a sufficient support span between the first ball bearing 30 and the second ball bearing 31 can be ensured, and tilting of the nut 8 can be further suppressed.

(7) The nut-side pulley belt winding portion 9b is positioned closer to the endless belt than the distance b between the center of the plurality of first balls 30c and the point O that bisects the endless belt 12 in the direction of the rotation axis P of the nut 8. 12 and the center of the plurality of second balls 31c are provided so as to be long.
Therefore, since the nut side pulley 9 is supported by a so-called cantilever structure with respect to the nut 8, the moment arm, which is the distance from the first ball bearing 30, which is the support point of the nut side pulley 9, to the endless belt 12 is long. Then, the inclination of the nut side pulley 9 increases due to the tensile force of the endless belt 12, but by providing the nut side pulley belt winding portion 9b at the position described above, the moment arm can be shortened and the inclination of the nut side pulley 9 is reduced. can be suppressed, and the occurrence of vibration in the speed reducer can be suppressed.

(8) The first ball bearing 30 and the second ball bearing 31 are provided in separate first housing 20a and second housing 20b, respectively.
Therefore, it is possible to improve the layout flexibility of the position of the nut 8 of each of the first ball bearing 30 and the second ball bearing 31 in the direction of the rotation axis P, so that the distance between the first ball bearing 30 and the second ball bearing 31 can be increased. can be set relatively long, the support span of the nut 8 becomes long, and the inclination of the nut can be further suppressed.

(9) The first outer race 30a of the first ball bearing 30 and the second outer race 31a of the second ball bearing 31 are fixed to the first housing 20a and the second housing 20b, respectively. The nut 8 and the nut-side pulley 9 are inserted when the race 30b and the second inner race 31b of the second ball bearing 31 are assembled.
Therefore, even when the housing is closed with the first housing 20a and the second housing 20b, the assembly work can be performed.

(10) A tapered portion 60 is formed at the outer peripheral end portion of the first ball bearing 30 of the nut-side pulley 9 in the direction in which it is inserted into the first inner race 30b.
Therefore, since the nut-side pulley 9 is inserted into the first inner race 30b along the tapered portion 60, the assembling workability is improved.

[Embodiment 2]
FIG. 3 is a partial cross-sectional view of Embodiment 2. FIG.

Unlike Embodiment 1, the first bearing holding portion 22 of the first ball bearing 30 and the second bearing holding portion 23 of the second ball bearing 31 are provided in the same second housing 20b.
Also, like the second ball bearing 31 of the first embodiment, the first outer race 30a of the first ball bearing 30 is secured to the second housing 20b by the first locknut 40 via a pair of first spring washers 42. A first stepped portion 22c and a first lock nut between a first large diameter portion 22a having a first inner diameter and a first small diameter portion 22b having a second inner diameter smaller than the first inner diameter of the bearing holding portion 22 40, it is directly fixed to and held by the first bearing holding portion 22 of the second housing 20b.
Since other configurations are the same as those of the first embodiment, members common to those of the first embodiment are given the same reference numerals as those of the first embodiment, and descriptions thereof are omitted.

Next, the effects of the second embodiment will be listed.
(1) The first bearing holding portion 22 of the first ball bearing 30 and the second bearing holding portion 23 of the second ball bearing 31 are provided in the same second housing 20b.
Therefore, high relative positional accuracy of the first ball bearing 30 and the second ball bearing 31 can be obtained regardless of the assembly accuracy of the first housing 20a and the second housing 20b.

(2) The first outer race 30a of the first ball bearing 30 and the second outer race 31a of the second ball bearing 31 are secured to the first bearing holding portion 22 of the second housing 20b by first and second lock nuts 40 and 41, respectively. and between the first and second stepped portions 22c and 23c between the first and second large diameter portions 22a and 23a and the first and second small diameter portions 22b and 23b of the second bearing holding portion 23, It is directly fixed to and held by the first bearing holding portion 22 and the second bearing holding portion 23 of the second housing 20b.
Therefore, it is possible to prevent the first outer race 30a of the first ball bearing 30 and the second outer race 31a of the second ball bearing 31 from coming off or shifting.

(3) The first outer race 30a of the first ball bearing 30 and the second outer race 31a of the second ball bearing 31 are secured by a pair of first and second spring washers 42, 42 by first and second lock nuts 40, 41, respectively. 43 between the first and second large diameter portions 22a and 23a and the first and second small diameter portions 22b and 23b of the first bearing holding portion 22 and the second bearing holding portion 23 of the second housing 20b. Between the first and second stepped portions 22c and 23c and the first and second lock nuts 40 and 41, the first and second bearing holding portions 22 and 23 of the second housing 20b are directly fixed and held. I made it to be.
Therefore, in addition to suppressing the vibration of the second ball bearing 31 and the nut 8 of the first embodiment, the vibration of the first ball bearing 30 can be suppressed.
Other functions and effects are the same as those of the first embodiment except for (8) and (9) described above.

[Embodiment 3]
FIG. 4 is a partial cross-sectional view of Embodiment 3. FIG.
Unlike the first embodiment, the first ball bearing 30 directly supports the nut 8 at a position near the first end 21a of the reduction gear housing space.
Also, the nut-side pulley 9 is fixed to the nut 8 by press-fitting.
Since other configurations are the same as those of the first embodiment, members common to those of the first embodiment are given the same reference numerals as those of the first embodiment, and descriptions thereof are omitted.

Next, functions and effects of the third embodiment are listed.
(1) The first ball bearing 30 and the second ball bearing 31 directly support the nut 8 .
Therefore, it is possible to employ a layout in which the nut 8 receives the tensile force of the endless belt 12 over the entire range of the endless belt 12 in the direction of the rotation axis P, and the tilting of the nut-side pulley 9 can be further suppressed.

(2) The first outer race 30a and the second outer race 31a are fixed to the first housing 20a and the second housing 20b, respectively. I tried to insert it.
Therefore, even when the housing is closed with the first housing 20a and the second housing 20b, the assembly work can be performed.
Other functions and effects are the same as those of the first embodiment except for (3), (4), and (9) described above.

[Embodiment 4]
FIG. 5 is a partial cross-sectional view of Embodiment 4. FIG.
Unlike Embodiment 3, the second inner race 8f (31b) of the second ball bearing 31 and the nut 8 are integrally constructed.
Since other configurations are the same as those of the third embodiment, members common to those of the first embodiment are assigned the same reference numerals as those of the first embodiment, and descriptions thereof are omitted.

Next, functions and effects of the fourth embodiment are listed.
(1) The second inner race 8f (31b) of the second ball bearing 31 and the nut 8 are integrated.
Therefore, it is possible to reduce the number of parts.
Other effects are the same as those of the third embodiment.

[Other embodiments]
As described above, the present invention has been described based on Embodiments 1 to 4, but the specific configuration of each invention is not limited to Embodiments 1 to 4, and is within the scope of the invention. Even if there is a design change etc., it is included in the present invention.

1 Power steering device (steering device)
2 steering mechanism 3 assist mechanism 4 rack bar (steering shaft)
4a rack bar main body (steering shaft main body)
4b Rack bar ball screw groove (steering shaft ball screw groove)
5 housing 6 electric motor 7 ball screw mechanism 8 nut 8a nut body 8b nut ball screw groove 8c first end 8d second end 8e screw female thread 9 nut side pulley (reducer)
9a through hole (nut-side pulley fixing part)
9b nut side pulley belt winding portion 9c nut side pulley tubular portion 9d nut side pulley boss portion 10 screw 11 electric motor side pulley (reduction gear)
11a Electric motor side pulley belt winding part 12 Endless belt (reduction gear)
15 Ball circulation groove 16 Ball 20 Housing main body 20a First housing 20b Second housing 21 Reduction gear housing space 21a Reduction gear housing space first end 21b Reduction gear housing space second end 22 First bearing holding part 22a First Large diameter portion 22b First small diameter portion 22c First stepped portion 23 Second bearing holding portion 23a Second large diameter portion 23b Second small diameter portion 23c Second stepped portion 30 First ball bearing (first bearing)
30a First outer race 30b First inner race 30c First ball 31 Second ball bearing (second bearing)
31a Second outer race 31b Second inner race 31c Second ball 40 First lock nut 41 Second lock nut 42 First spring washer 43 Second spring washer 60 Tapered portion a Ball circulation range of tube b Dividing the endless belt into two equal parts Distance c between a point and the center of the first ball Distance between a point bisecting the endless belt and the center of the second ball O A point P bisecting the endless belt Axis of rotation

Claims (11)

A steering device,
A housing comprising a housing body, a reduction gear housing space, a first bearing holding portion, and a second bearing holding portion,
The housing body has a first housing and a second housing combined with the first housing,
the housing;
a steered shaft comprising a steered shaft main body and a steered shaft ball screw groove, provided movably in the longitudinal direction of the steered shaft inside the housing;
The steered shaft main body has a rod shape,
The steered shaft ball screw groove is provided on the outer peripheral side of the steered shaft main body and has a spiral groove shape.
the steering shaft;
A nut having a nut body and a nut ball screw groove, and provided rotatably inside the reduction gear housing space,
The nut main body has a tubular shape, and the steering shaft is inserted therein,
The nut ball screw groove has a spiral groove shape formed on the inner peripheral side of the nut body,
the nut;
A plurality of balls provided between the steered shaft ball screw groove and the nut ball screw groove, and axially moving the steered shaft in the direction of the rotation axis of the nut as the nut rotates. said ball of
a nut-side pulley including a nut-side pulley cylindrical portion and a nut-side pulley boss portion, and having a nut-side pulley fixing portion and a nut-side pulley belt winding portion having a cylindrical shape,
the nut-side pulley partially overlaps the nut in the direction of the rotation axis of the nut;
comprising a plurality of screws connecting the nut and the nut-side pulley,
The nut-side pulley is movable relative to the nut in a radial direction with respect to the rotation axis of the nut in a state before being connected to the nut by the screw,
The nut-side pulley tubular portion has a tubular shape, and the nut-side pulley winding portion is provided radially outward with respect to the rotation axis of the nut,
The nut-side pulley boss portion is provided in the nut-side pulley cylindrical portion so as to face the nut in the direction of the rotation axis of the nut, and includes a plurality of screw through holes as the nut-side pulley fixing portion,
The nut has a plurality of screw female threads that open at positions facing the plurality of screw through holes,
The plurality of screws connect the nut and the nut-side pulley by coupling with the female screw portion through the screw through-holes.
the nut-side pulley;
an electric motor-side pulley having an electric motor-side pulley belt winding portion,
The electric motor side pulley belt winding portion has a cylindrical shape,
the electric motor side pulley;
An endless belt, which is wound around both the nut-side pulley belt winding portion and the electric motor-side pulley belt winding portion, and transmits rotation of the electric motor-side pulley to the nut-side pulley,
the endless belt;
The first bearing is held by the first bearing holding portion and is a pair of ends of the nut in the direction of the rotation axis of the nut. provided in a predetermined region including an end portion, supports the nut via the nut-side pulley, and supports the nut rotatably with respect to the housing;
the first bearing;
A second bearing held by the second bearing holding portion and provided in a predetermined region including the second end portion in the direction of the rotation axis of the nut to rotatably support the nut with respect to the housing. do,
the second bearing;
An electric motor, which imparts a rotational force to the electric motor-side pulley;
the electric motor;
A steering device characterized by: The steering device according to claim 1,
the first housing and the second housing are respectively provided on one side and the other side of the housing in the direction of the rotational axis of the nut;
The first bearing holding portion and the second bearing holding portion are provided in the second housing,
A steering device characterized by: The steering device of claim 2 comprises a first lock nut and a second lock nut,
The first bearing is a ball bearing including a first outer race, a first inner race, and a plurality of first balls,
The second bearing is a ball bearing including a second outer race, a second inner race, and a plurality of second balls,
The first outer race is fastened to the second housing by the first lock nut at the first bearing holding portion,
The second outer race is fastened to the second housing by the second lock nut at the second bearing holding portion,
A steering device characterized by: The steering device according to claim 3, wherein the steering device comprises a first spring washer and a second spring washer,
The first bearing holding portion includes a first large diameter portion in which the inner diameter of the second housing in a radial direction with respect to the rotation axis of the nut is a first inner diameter, and an inner diameter of the second housing is larger than the first inner diameter. including a first reduced diameter portion having a second inner diameter smaller than
The first outer race is held between the first step portion between the first large diameter portion and the first small diameter portion and the first lock nut together with the first spring washer,
The second bearing holding portion includes a second large diameter portion in which the inner diameter of the second housing in the radial direction with respect to the rotation axis of the nut is a third inner diameter, and an inner diameter of the second housing is larger than the third inner diameter. including a second reduced diameter portion having a fourth inner diameter smaller than
The second outer race is held between the second lock nut and the second step portion between the second large diameter portion and the second small diameter portion together with the second spring washer.
A steering device characterized by: The steering device according to claim 1,
The first bearing is a ball bearing including a first outer race, a first inner race and a plurality of first balls, and the second bearing includes a second outer race, a second inner race and a plurality of second balls. a ball bearing,
The second bearing directly supports the nut,
the diameter of the plurality of first balls is smaller than the diameter of the plurality of second balls;
A steering device characterized by: The steering device according to claim 1,
The speed reducer housing space has a first end of the speed reducer housing space and a second end of the speed reducer housing space, which are a pair of ends in the direction of the rotational axis of the nut,
The first bearing is arranged such that, in the direction of the rotation axis of the nut, the reduction gear is positioned further than the range in which the plurality of balls circulates in a ball screw groove formed by the steered shaft ball screw groove and the nut ball screw groove. It is provided at a position close to the first end of the accommodation space,
The second bearing is provided at a position closer to the second end of the speed reducer housing space than the range in which the plurality of balls circulate in the ball screw groove in the direction of the rotation axis of the nut.
A steering device characterized by: In the steering device according to claim 6,
The first bearing is a ball bearing that supports the nut via the nut-side pulley and includes a first outer race, a first inner race, and a plurality of first balls,
The second bearing directly supports the nut and is a ball bearing including a second outer race, a second inner race, and a plurality of second balls,
The nut-side pulley fixing portion is provided on the opposite side of the nut-side pulley winding portion with respect to the first bearing in the direction of the rotation axis of the nut,
The nut-side pulley winding portion is located at a point that bisects the endless belt more than a distance between a point that bisects the endless belt in the direction of the rotation axis of the nut and the centers of the plurality of first balls. and the distance from the center of the plurality of second balls is long,
A steering device characterized by: The steering device according to claim 1,
The nut-side pulley is such that the entire nut-side pulley overlaps the nut in the direction of the rotation axis of the nut,
The second bearing directly supports the nut, and is a ball bearing including a second outer race, a plurality of second balls, and a second inner race portion,
The second inner race portion is formed integrally with the nut,
A steering device characterized by: The steering device according to claim 1,
the first housing and the second housing are respectively provided on one side and the other side of the housing in the direction of the rotational axis of the nut;
The first bearing holding portion is provided in the first housing,
The second bearing holding portion is provided in the second housing,
A steering device characterized by: In the steering device according to claim 9 ,
The first bearing is a ball bearing including a first outer race, a first inner race, and a plurality of first balls,
The second bearing is a ball bearing including a second outer race, a second inner race, and a plurality of second balls,
The first outer race is fixed to the first bearing holding portion,
The first inner race has the nut or the nut-side pulley inserted inside,
The second outer race is fixed to the second bearing holder,
A steering device characterized by: In the steering device according to claim 10,
The speed reducer housing space has a first end of the speed reducer housing space and a second end of the speed reducer housing space, which are a pair of ends in the direction of the rotational axis of the nut,
The nut or the nut-side pulley is provided at one of a pair of ends of the nut in the direction of the rotation axis that is closer to the first end of the reduction gear housing space,
a tapered portion in which the outer diameter of the nut with respect to the rotational axis of the nut gradually increases in the direction from the first end of the speed reducer housing space toward the second end of the speed reducer housing space;
A steering device characterized by:

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