JP5158415B2 - Electric power steering device - Google Patents

Description

  The present invention relates to an electric power steering apparatus.

Some electric power steering apparatuses include an electric motor coaxially connected to a steering shaft as described in Patent Document 1 below, for example. In Patent Document 1, a rotor of an electric motor is connected to a steering shaft, and a stator is fixed to a motor housing.
JP 2006-103642 A

In an electric power steering apparatus, improvement in steering feeling is desired. Specifically, for example, it is desired to improve the steering feeling by reducing the cogging torque of the electric motor. The reduction of the cogging torque is achieved, for example, by improving the coaxiality between the rotor and the stator.
The present invention has been made based on such a background, and an object thereof is to provide an electric power steering apparatus in which steering feeling is improved by reducing cogging torque.

In order to achieve the above object, the present invention includes an annular rotor (24) coaxially connected to the steering shaft (3), and an annular stator (25) held by a motor housing (26) and surrounding the rotor. The motor housing includes a cylindrical motor case (35), and the motor case includes an outer cylindrical portion (32) in which a stator is coaxially held, and the outer cylindrical portion. The inner cylindrical portion (33) disposed coaxially with the inner cylindrical portion and a connecting plate (34) for connecting both cylindrical portions, and the outer cylindrical portion, the inner cylindrical portion, and the connecting plate are integrally formed. In addition, the steering shaft is an electric power steering device (1) characterized in that the steering shaft is coaxially supported by an inner cylindrical portion (claim 1).

  According to the present invention, the coaxiality between the rotor and the stator can be improved by coaxially supporting the steering shaft by the inner cylindrical portion of the motor case. As a result, the cogging torque of the electric motor is reduced, and the steering feeling of the electric power steering device is improved. The steering shaft may be directly supported by the inner cylindrical portion or indirectly supported.

The steering shaft may be coaxially supported by the inner cylindrical portion via a support member (17) that coaxially supports the steering shaft. By supporting the support member coaxially by the inner cylindrical portion, the steering shaft is coaxially supported by the inner cylindrical portion.
The support member includes a cylindrical sensor housing (17) in which a torque sensor (13) is accommodated. The sensor housing has a large-diameter cylindrical portion (20) that coaxially supports the steering shaft, and an annular shape. A small-diameter cylindrical portion (22) coaxially connected to the large-diameter cylindrical portion via a step portion (21), and the large-diameter cylindrical portion is fitted to the inner periphery of the inner cylindrical portion, In some cases, the large-diameter cylindrical portion is coaxially supported by the inner cylindrical portion. In this case, the steering shaft is coaxially supported by the inner cylindrical portion by fitting the large diameter cylindrical portion of the sensor housing to the inner cylindrical portion of the motor case. This reliably reduces the cogging torque of the electric motor.

  The large-diameter cylindrical portion may be press-fitted into the inner periphery of the inner cylindrical portion. That is, the large-diameter cylindrical portion may be coaxially supported by the inner cylindrical portion by press-fitting the large-diameter cylindrical portion into the inner periphery of the inner cylindrical portion. In this case, the coaxiality between the large-diameter cylindrical portion and the inner cylindrical portion can be improved, and as a result, the coaxiality between the rotor and the stator can be improved. This further reliably reduces the cogging torque of the electric motor.

  The small-diameter cylindrical portion is fitted to the inner periphery of a cylindrical column housing (16) that rotatably supports the steering shaft, and the end portion (15a) of the column housing is an annular step of the sensor housing. There is a case where it is positioned in the axial direction (X1) of the steering shaft by engaging with the portion (21). In this case, not only can the torque sensor be accommodated by the sensor housing, but also the column housing can be positioned in the axial direction of the steering shaft, so the number of components of the electric power steering device can be reduced.

The sensor housing may be formed by press-molding a single member. The motor case may be formed by press-molding a single member.
By forming at least one of the sensor housing and the motor case by press molding, the manufacturing cost of the electric power steering device can be reduced. Further, by forming the motor case with a single member, the coaxiality of the outer cylindrical portion and the inner cylindrical portion can be improved as compared with a motor case formed with a plurality of separate members. As a result, the cogging torque of the electric motor can be further reduced, and the steering feeling of the electric power steering apparatus can be further improved.

  In the above description, the alphanumeric characters in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing a schematic configuration of an electric power steering apparatus 1 according to an embodiment of the present invention. FIG. 2 is an enlarged view of a part of FIG.
Referring to FIG. 1, an electric power steering apparatus 1 includes a steering shaft 3 as a steering shaft to which a steering member 2 such as a steering wheel is connected, and a cylindrical steering column 4 that rotatably supports the steering shaft 3. The steering assisting electric motor 5 is connected to the steering shaft 3 coaxially.

  The steering shaft 3 extends linearly and includes an upper shaft 6, a lower shaft 7, an input shaft 8 and an output shaft 9. Each shaft 6-9 is cylindrical and is arrange | positioned coaxially. A steering member 2 is connected to one end (upper end in FIG. 1) of the upper shaft 6 so as to be able to rotate together. Further, a steering mechanism 10 made of, for example, a rack and pinion mechanism is connected to one end (lower end in FIG. 1) of the output shaft 9 via an intermediate shaft (not shown). The steering member 2 and the steering mechanism 10 are mechanically connected via a steering shaft 3 and an intermediate shaft.

By transmitting the rotation from the steering member 2 to the steering mechanism 10 via the steering shaft 3 and the intermediate shaft, steered wheels (not shown) can be steered. In the following, the steering member 2 side along the axial direction X1 of the steering shaft 3 is defined as the upper side, and the steering mechanism 10 side is defined as the lower side.
On the inner periphery of the lower end portion of the upper shaft 6, a part of the lower shaft 7 is serrated, for example. The upper shaft 6 and the lower shaft 7 are coupled so as to be able to rotate together and to be relatively movable in the axial direction X1 of the steering shaft 3. Further, the upper end portion of the input shaft 8 is fitted into the lower end portion of the lower shaft 7. The lower end portion of the lower shaft 7 and the upper end portion of the input shaft 8 are connected by a pin 11a so as to be able to rotate together.

  Further, the lower end portion of the input shaft 8 is fitted into the upper end portion of the output shaft 9. The input shaft 8 and the output shaft 9 are connected via a torsion bar 12 so as to be relatively rotatable. The torsion bar 12 is inserted through the center holes of the input shaft 8 and the output shaft 9 and coaxially connects the input shaft 8 and the output shaft 9. The upper end portion of the torsion bar 12 is connected to the upper end portion of the input shaft 8 by a pin 11a so as to be able to rotate together. Moreover, the lower end part of the torsion bar 12 is connected to the lower end part of the output shaft 9 by a pin 11b so as to be able to rotate together.

  When the steering member 2 is operated (rotated), a rotational torque as a steering torque is input to the input shaft 8 via the upper shaft 6 and the lower shaft 7. At this time, the torsion bar 12 transmits the steering torque to the output shaft 9 while undergoing elastic torsional deformation with a magnitude proportional to the steering torque. As a result, the output shaft 9 rotates about its central axis while the input shaft 8 and the output shaft 9 rotate relative to each other.

  A torque sensor 13 disposed near the fitting portion of the input shaft 8 and the output shaft 9 is a steering torque input to the steering member 2 based on a change in magnetic resistance caused by relative rotation of the input shaft 8 and the output shaft 9. Is detected. The torque detection result detected by the torque sensor 13 is input to an ECU 19 (Electronic Control Unit).

The steering column 4 includes a column housing 16 including a cylindrical upper column 14 and a cylindrical lower column 15 extending linearly, and a cylindrical sensor housing 17 as a support member in which the torque sensor 13 is accommodated on the inner periphery. Including. The upper column 14, the lower column 15, and the sensor housing 17 are arranged coaxially.
A part of the lower column 15 is fitted into the lower end portion of the upper column 14. The upper column 14 and the lower column 15 are coupled so as to be relatively movable in the axial direction of the steering column 4 (in FIG. 1, the same direction as the axial direction X1). Further, the upper end portion of the sensor housing 17 (specifically, a small-diameter cylindrical portion 22 described later) is fitted into the lower end portion of the lower column 15. The lower column 15 and the sensor housing 17 are fixed to each other.

  The upper column 14 is fixed to the vehicle body side member B with a predetermined fixing strength by a first bracket 18 a fixed to the upper column 14. The sensor housing 17 is held by a motor housing 26 (described later) fixed to the vehicle body side member B by the second bracket 18b. The lower column 15 is fitted to the upper column 14.

The first bracket 18a is attached to the vehicle body side member B via, for example, a breakable synthetic resin pin 11c. When an impact of a predetermined value or more is applied to the first bracket 18a at the time of a vehicle collision, the pin 11c is broken and the upper column 14 and the vehicle body side member B are released from being fixed.
The steering shaft 3 is inserted through the upper column 14, the lower column 15 and the sensor housing 17. The steering shaft 3 is rotatably supported inside the upper column 14, the lower column 15 and the sensor housing 17.

  Specifically, the upper shaft 6 is rotatably supported by the upper column 14 via a bearing 50a. The input shaft 8 is rotatably supported by the sensor housing 17 via a bearing 50b, and the output shaft 9 is rotatably supported by the sensor housing 17 via a bearing 50c. As the bearings 50a, 50b, and 50c, for example, rolling bearings can be used. In the present embodiment, radial ball bearings are used as the bearings 50a, 50b, and 50c, respectively.

  Referring to FIG. 2, the sensor housing 17 includes a large-diameter cylindrical portion 20 that coaxially supports the steering shaft 3, and a small-diameter cylindrical portion that is coaxially connected to the large-diameter cylindrical portion 20 via an annular step portion 21. 22. The sensor housing 17 is formed by press-molding a single member. The annular step portion 21 extends from the upper end portion of the large diameter cylindrical portion 20 toward the inside in the radial direction of the large diameter cylindrical portion 20. The small diameter cylindrical portion 22 extends from the inner peripheral portion of the annular step portion 21 upward in the axial direction X1. The large diameter cylindrical portion 20, the annular step portion 21, and the small diameter cylindrical portion 22 are arranged coaxially.

  The sensor housing 17 is held by the motor housing 26 as described above. In a state where the sensor housing 17 is held by the motor housing 26, the small diameter cylindrical portion 22 protrudes upward in the axial direction X <b> 1 from the upper end of the motor housing 26. A lower end portion of the lower column 15 is fitted on the small diameter cylindrical portion 22, and an annular flange 15 a provided at the lower end of the lower column 15 is engaged with an upper end surface 21 a of the annular step portion 21. The lower column 15 is positioned and received by the annular step portion 21 below the axial direction X1. By positioning the lower column 15 downward in the axial direction X1 by the annular step portion 21, the number of parts of the electric power steering apparatus 1 is reduced. That is, a dedicated positioning member for positioning the lower column 15 downward in the axial direction X1 is reduced.

  The torque sensor 13 is disposed between the inner periphery of the large diameter cylindrical portion 20 and the outer periphery of the steering shaft 3. The torque sensor 13 is disposed at the intermediate portion in the axial direction of the large diameter cylindrical portion 20. The bearing 50b and the bearing 50c described above are held by the inner periphery of the large-diameter cylindrical portion 20. The bearing 50b and the bearing 50c are respectively disposed on both sides of the torque sensor 13 in the axial direction X1. The bearing 50 b is held at the upper end portion of the large diameter cylindrical portion 20 via the annular spacer 23, and the bearing 50 c is held at the lower end portion of the large diameter cylindrical portion 20. In a state where the output shaft 9 is rotatably supported by the large diameter cylindrical portion 20 via the bearing 50c, the center axis L1 of the output shaft 9 and the center axis L2 of the outer peripheral surface of the large diameter cylindrical portion 20 are substantially on the same axis. Is arranged.

The electric motor 5 includes an annular rotor 24 coaxially connected to the steering shaft 3, an annular stator 25 that surrounds the rotor 24, and a bottomed cylindrical motor housing 26 that houses the rotor 24 and the stator 25. ing. As the electric motor 5, for example, a brushless motor can be used.
The rotor 24 includes a cylindrical rotor core 27 and an annular permanent magnet 28 fixed to the outer peripheral surface of the rotor core 27. As the permanent magnet 28, for example, a multipolar ring magnet or a plurality of segment magnets arranged in an annular shape can be used. The outer peripheral surface of the rotor 24 is substantially cylindrical, and is a magnetic pole in which the N pole and the S pole are alternately replaced in the circumferential direction.

  The rotor core 27 surrounds the steering shaft 3 at a predetermined interval in the radial direction of the rotor core 27. An annular space S <b> 1 that surrounds the steering shaft 3 is formed inside the rotor core 27 in the radial direction. The rotor core 27 is coaxially connected to the output shaft 9 by a connecting member 29 disposed in the annular space S1. The connecting member 29 is an annular member having a shorter axial length (length in the axial direction X1) than the rotor core 27.

  The connecting member 29 is press-fitted into the inner periphery of the rotor core 27, for example. Thereby, the connecting member 29 and the rotor core 27 are connected so as to be able to rotate together and transmit torque. Further, the output shaft 9 is press-fitted into the inner periphery of the connecting member 29, for example. Thereby, the connection member 29 and the output shaft 9 are connected so as to be able to rotate together and transmit torque.

  In a state where the rotor core 27 is connected to the output shaft 9 via the connecting member 29, the central axis L3 of the outer peripheral surface of the permanent magnet 28 and the central axis L1 of the output shaft 9 are arranged on substantially the same axis. The connecting member 29 is formed with a lightening hole 30 that penetrates the connecting member 29 in the thickness direction (the same direction as the axial direction X1 in FIG. 2). Thereby, the connection member 29 is reduced in weight.

  The stator 25 includes an annular stator core 31 and a plurality of coils (not shown) wound around the stator core 31. The inner peripheral surface and the outer peripheral surface of the stator core 31 are each generally cylindrical. The stator core 31 surrounds the rotor 24 so that the inner peripheral surface thereof faces the outer peripheral surface of the rotor 24 (the outer peripheral surface of the permanent magnet 28). Although not shown, the stator core 31 includes an annular yoke and a plurality of teeth protruding radially inward from the inner periphery of the yoke. The plurality of coils are wound around a plurality of teeth, respectively. Each coil is supplied with power from a power supply source (not shown). Supply of electric power to each coil is controlled by the ECU 19.

The motor housing 26 includes a cylindrical motor case 35 and a lid member 36 fixed to the motor case 35. The motor case 35 includes an outer cylindrical portion 32 in which the stator 25 is coaxially held, an inner cylindrical portion 33 that is coaxially disposed inside the outer cylindrical portion 32, and a coupling that connects both the cylindrical portions 32 and 33. Plate 34.
The motor case 35 is formed by press-molding a single member. The length of the inner cylindrical portion 33 in the axial direction X1 is shorter than that of the outer cylindrical portion 32. Further, with respect to the axial direction X1, the position of the upper end of the inner cylindrical portion 33 and the position of the upper end of the outer cylindrical portion 32 are substantially aligned. The connecting plate 34 is, for example, an annular flat plate, and connects the upper ends of both cylindrical portions 32 and 33. That is, the outer peripheral portion of the connecting plate 34 is connected to the upper end of the outer cylindrical portion 32, and the inner peripheral portion of the connecting plate 34 is connected to the upper end of the inner cylindrical portion 33.

Further, the central axis L4 of the inner peripheral surface of the inner cylindrical portion 33 and the central axis L5 of the inner peripheral surface of the outer cylindrical portion 32 are arranged on substantially the same axis. In this embodiment, since the motor case 35 is formed by a single member, the inner peripheral surface of the outer cylindrical portion 32 and the inner peripheral portion of the inner cylindrical portion 33 are compared with a motor housing formed by a plurality of separate members. The coaxiality with the surface is improved.
An accommodation space S <b> 2 for accommodating the rotor 24 and the stator 25 is formed inside the outer cylindrical portion 32. In a state where the rotor 24 is accommodated in a predetermined position of the accommodation space S2, a part of the inner cylindrical portion 33 is disposed in the annular space S1 described above. The lid member 36 is fixed to the lower end portion of the outer cylindrical portion 32 and substantially covers the opening portion at the lower end portion of the outer cylindrical portion 32.

  The lid member 36 includes an annular plate-shaped portion 37 and a cylindrical portion 38 formed at the center of the plate-shaped portion 37. The second bracket 18b described above is fixed to the plate-like portion 37 (see FIG. 1). Further, a cylindrical fitting portion 39 that is fitted into the lower end portion of the outer cylindrical portion 32 is formed on the outer peripheral portion of the plate-like portion 37 so as to protrude upward in the axial direction X1. The tubular portion 38 is connected to the inner peripheral portion of the plate-like portion 37 and extends upward from the plate-like portion 37 in the axial direction X1. The output shaft 9 is inserted through the inner periphery of the tubular portion 38 and is rotatably supported by the tubular portion 38 via a bearing 50d held on the inner periphery of the tubular portion 38.

  A resolver 40 is disposed on the inner periphery of the cylindrical portion 38, and the rotational position of the rotor 24 is detected by the resolver 40. The resolver 40 can detect the rotational position of the rotor 24 by detecting the rotational position of the output shaft 9. A part of the resolver 40 enters the annular space S1. In the state where the resolver 40 is disposed on the inner periphery of the tubular portion 38, an annular cover 42 is fixed to the lower end portion of the tubular portion 38 by, for example, a bolt 41. The detection device that detects the rotational position of the rotor 24 is not limited to the resolver 40, and other detection devices such as a rotary encoder may be used.

  The stator core 31 is press-fitted, for example, into the inner periphery of the outer cylindrical portion 32. Thereby, the stator core 31 is fixed to the outer cylindrical portion 32. In a state where the stator core 31 is fixed to the outer cylindrical portion 32, the central axis L6 of the inner peripheral surface of the stator core 31 and the central axis L5 of the inner peripheral surface of the outer cylindrical portion 32 are arranged on substantially the same axis. That is, in a state where the stator core 31 is fixed to the outer cylindrical portion 32, the central axis L6 of the inner peripheral surface of the stator core 31 and the central axis L4 of the inner peripheral surface of the inner cylindrical portion 33 are arranged on substantially the same axis. Yes.

  As described above, in the present embodiment, since the stator core 31 is press-fitted into the outer cylindrical portion 32, the inner circumferential surface of the stator core 31 is compared with the case where the stator core 31 is fixed to the outer cylindrical portion 32 by, for example, adhesion. The coaxiality with the inner peripheral surface of the outer cylindrical portion 32 is improved. Thereby, the coaxiality of the inner peripheral surface of the stator core 31 and the inner peripheral surface of the inner cylindrical portion 33 is improved.

  The large diameter cylindrical portion 20 of the sensor housing 17 is coaxially supported by the inner cylindrical portion 33. Specifically, the large-diameter cylindrical portion 20 is, for example, press-fitted into the inner periphery of the inner cylindrical portion 33, and thereby the large-diameter cylindrical portion 20 is fixed to the inner cylindrical portion 33. In a state where the large-diameter cylindrical portion 20 is fixed to the inner cylindrical portion 33, a part of the large-diameter cylindrical portion 20 enters the annular space S1 from above the axial direction X1. A part of the large-diameter cylindrical portion 20, the torque sensor 13, and the like are arranged in the annular space S1. That is, in this embodiment, the electric power steering device 1 is downsized in the axial direction X1 by effectively using the space inside the rotor core 27.

  Further, in a state where the large-diameter cylindrical portion 20 is fixed to the inner cylindrical portion 33, the central axis L4 of the inner peripheral surface of the inner cylindrical portion 33 and the central axis L1 of the output shaft 9 supported by the large-diameter cylindrical portion 20 Are arranged substantially on the same axis. Since the output shaft 9 is coaxially disposed with respect to the inner peripheral surface of the inner cylindrical portion 33, the coaxiality between the rotor 24 and the stator 25 is improved (specifically, the outer peripheral surface of the permanent magnet 28). And the coaxiality between the stator core 31 and the inner peripheral surface is improved.)

In the present embodiment, since the large-diameter cylindrical portion 20 is press-fitted into the inner cylindrical portion 33, for example, an adhesive layer is interposed between the large-diameter cylindrical portion 20 and the inner cylindrical portion 33 to fix the both 20,30. Compared to the case, the coaxiality of the output shaft 9 with respect to the inner peripheral surface of the inner cylindrical portion 33 is improved. Thereby, the coaxiality of the rotor 24 and the stator 25 is further improved.
Referring to FIG. 1 again, the electric motor 5 is controlled by the ECU 19. That is, the ECU 19 drives and controls the electric motor 5 based on a torque detection result from the torque sensor 13 or a vehicle speed detection result from a vehicle speed sensor (not shown). When the ECU 19 controls the electric motor 5, output torque as steering assist force is directly transmitted from the electric motor 5 to the output shaft 9. Then, a steering assist force is transmitted from the output shaft 9 to the steering mechanism 10 to assist the driver's steering.

As described above, in the present embodiment, the coaxiality between the rotor 24 and the stator 25 can be improved by coaxially supporting the steering shaft 3 by the inner cylindrical portion 33 of the motor case 35. Thereby, the cogging torque of the electric motor 5 can be reduced, and the steering feeling of the electric power steering apparatus 1 can be improved.
Further, as described above, in the present embodiment, since the large-diameter cylindrical portion 20 is press-fitted into the inner cylindrical portion 33, the coaxiality of the output shaft 9 with respect to the inner peripheral surface of the inner cylindrical portion 33 is improved. Thereby, the coaxiality of the rotor 24 and the stator 25 is further improved. In the present embodiment, since the sensor housing 17 and the motor case 35 are formed by press molding, the electric power steering device 1 is manufactured as compared with the case where the sensor housing 17 and the motor case 35 are formed by cutting, for example. Cost has been reduced.

  The present invention is not limited to the contents of the above embodiments, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, the case where the present invention is applied to the so-called column assist type electric power steering device 1 in which the output torque of the electric motor 5 is transmitted to the steering shaft 3 has been described. For example, the present invention may be applied to other electric power steering devices such as a so-called pinion assist type electric power steering device.

  Moreover, although the above-mentioned embodiment demonstrated the case where the sensor housing 17 and the motor case 35 were each formed by press-molding a single member, it is not restricted to this. That is, the sensor housing 17 and the motor case 35 may each be configured by a plurality of separate members. Moreover, you may form by processing methods other than press processing. More specifically, the sensor housing 17 and the motor case 35 may be formed by cutting or casting, respectively.

  In the above-described embodiment, the case where the steering shaft 3 as the steering shaft is coaxially supported by the inner cylindrical portion 33 via the sensor housing 17 or the like has been described. The steering shaft 3 may be supported coaxially and rotatably by the cylindrical portion 33 directly or via a bearing.

It is sectional drawing which shows typically schematic structure of the electric power steering apparatus which concerns on one Embodiment of this invention. It is the figure which expanded a part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric power steering device, 3 ... Steering shaft (steering shaft), 5 ... Electric motor, 13 ... Torque sensor, 15a ... Annular flange (end part of column housing), 16 ..Column housing, 17... Sensor housing (support member), 20... Large diameter cylindrical portion, 21... Annular step, 22. -Stator, 26 ... motor housing, 32 ... outer cylindrical part, 33 ... inner cylindrical part, 34 ... connecting plate, 35 ... motor case, X1 ... axial direction

Claims (7)

An electric rotor including an annular rotor coaxially connected to the steering shaft, and an annular stator held in a motor housing and surrounding the rotor;
The motor housing includes a cylindrical motor case,
The motor case includes an outer cylindrical portion in which a stator is coaxially held, an inner cylindrical portion that is coaxially disposed inside the outer cylindrical portion, and a connecting plate that connects both cylindrical portions,
The outer cylindrical portion, the inner cylindrical portion, and the connecting plate are integral.
The electric power steering apparatus, wherein the steering shaft is coaxially supported by an inner cylindrical portion.   2. The electric power steering apparatus according to claim 1, wherein the steering shaft is coaxially supported by the inner cylindrical portion via a support member that coaxially supports the steering shaft. 3. The support member according to claim 2, wherein the support member includes a cylindrical sensor housing in which a torque sensor is accommodated.
The sensor housing includes a large-diameter cylindrical portion that coaxially supports the steering shaft, and a small-diameter cylindrical portion that is coaxially connected to the large-diameter cylindrical portion via an annular stepped portion,
The electric power steering device according to claim 1, wherein the large-diameter cylindrical portion is fitted on the inner periphery of the inner cylindrical portion, so that the large-diameter cylindrical portion is coaxially supported by the inner cylindrical portion.   4. The electric power steering apparatus according to claim 3, wherein the large-diameter cylindrical portion is coaxially supported by the inner cylindrical portion by press-fitting the large-diameter cylindrical portion into the inner periphery of the inner cylindrical portion. In Claim 3 or 4, the small-diameter cylindrical portion is fitted to the inner periphery of a cylindrical column housing that rotatably supports the steering shaft,
The electric power steering apparatus according to claim 1, wherein an end of the column housing is positioned in an axial direction of the steering shaft by engaging with an annular step of the sensor housing.   6. The electric power steering device according to claim 3, wherein the sensor housing is formed by press-molding a single member.   7. The electric power steering apparatus according to claim 1, wherein the motor case is formed by press-molding a single member.

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