JP2018176756A - Electric power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric power steering unit which can inhibit rattle sound that may be generated by a ball screw supporting bearing,as well as inhibit dimension change that may occur due to difference between coefficients of thermal expansion of ball screw supporting bearing and housing, and which can be made of a reduced number of parts.SOLUTION: An electric power steering unit comprises a ball screw mechanism having a ball screw shaft 6, a ball screw nut 4, and balls 7, a housing 2 which stores the ball screw mechanism, a ball screw supporting bearing 8 which is arranged between the housing 2 and the ball screw nut 4, and an electric motor which is arranged in a shaft different from the ball screw shaft 6, and is used for driving of the ball screw nut 4. Elastic portions Q are provided in end portions of a cylindrical portion 11a and an annular portion 11b between the ball screw supporting bearing 8 and the housing 2, and a bearing case 10 is assembled in a state where a preload force is generated in an elastic portion Q2 of the annular portion 11b.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ball screw rack assist type electric power steering apparatus.

  In recent years, the demand for hybrids and electric vehicles has increased due to environmental considerations, and quietness is required for electric power steering devices (EPS: hereinafter referred to as EPS) mounted on these. It is a problem that rattle noise (beat sound) is generated by vibration from the vehicle. The rattling noise is mainly generated due to backlash between the ball screw nut and the ball screw shaft, the rack gear and the pinion gear. In particular, in a ball screw type rack assist type EPS in which a rack shaft is driven by an electric ball screw mechanism, a ball screw portion and a bearing supporting the same are close to a tire, and a component acting as a damper along the reaction force transmission path. There is little, it is easy to vibrate. The vibrations are transmitted to the steering wheel and cause the driver to feel uncomfortable.

  Then, patent documents 1 and patent documents 2 are proposed as what solves these problems. In Patent Document 1, the technical idea is that the bearing is set in a housing provided with a convex portion on the circumferential surface of a ball screw support bearing and elastically supported in the axial direction by inserting elastic members at both ends of the ball screw support bearing. It is disclosed. Further, in Patent Document 2, in addition to the operation and effect of Patent Document 1, the ball screw support bearing can be further tilted.

However, in the configuration of this patent document 1, depending on the setting of the elastic force of the elastic member, the outer ring of the ball screw support bearing is rotated by the external force input through the rack shaft or the rotational force input through the ball screw nut. There is a possibility that the convex part provided in the housing may wear. In addition, the gap may increase or decrease due to the dimensional change due to the difference in thermal expansion coefficient between the housing cover and the bearing, and the rattle noise may not be prevented.
In Patent Document 2 as well, the dimensional change due to the difference in thermal expansion coefficient between the housing and the ball screw support bearing may increase or decrease the gap, and the rattle noise may not be prevented. Moreover, when another part is inserted between the bearing and the housing, the cost increases because the parts and the number of assembling steps increase.

WO / 2008/017541 US9033097

  Therefore, the present invention has been made in view of the problems described above, and its object is to suppress rattling noise generated between a ball screw, a ball screw support bearing or a bearing and a housing, and a ball screw support bearing. Another object of the present invention is to provide an electric power steering apparatus with a reduced number of parts, which can suppress dimensional change caused by the difference between the thermal expansion coefficient of the housing and the housing.

In order to achieve such an object, the electric power steering apparatus according to the first invention is provided on a ball screw shaft having a spiral groove formed on the outer peripheral surface, and on the outer periphery of the ball screw shaft. A ball screw mechanism including a ball screw nut in which a groove is formed, a spiral groove of the ball screw nut, and a ball disposed in a rolling path formed by the spiral groove of the ball screw shaft; A housing for housing, a ball screw support bearing disposed between the housing and the ball screw nut, and an electric motor disposed on a shaft separate from the ball screw shaft and used to drive the ball screw nut; Between the ball screw support and the housing, and a cylindrical portion, and an annular portion continuously provided radially inward from one end of the cylindrical portion A bearing case is disposed, an elastic portion is provided at an end of the cylindrical portion and the annular portion, and the bearing case is assembled to the housing in a state where a preload is generated in the elastic portion of the annular portion. It is characterized by
According to a second invention, in the first invention, an axial contact width between the cylindrical portion of the bearing case and the housing is smaller than an axial width of the ball screw support bearing.
According to a third invention, in the first invention or the second invention, positioning of a ball screw support bearing is performed by an annular portion of the bearing case.
According to a fourth invention, in any one of the first invention to the third invention, at least one of the cylindrical portion and the annular portion has an elastic modulus changing portion in which elastic modulus changes.
According to a fifth invention, in the fourth invention, the elastic modulus changing portion is a hole or a thin portion.
According to a sixth invention, in any one of the first invention to the fifth invention, a soundproof member is disposed between the housing and the bearing case, at least on one of the bearing case or the housing. It is characterized by
According to a seventh invention, in the sixth invention, the soundproofing member is a resin, a rubber or an adhesive.
The eighth invention is characterized in that, in the seventh invention, the soundproofing member is disposed by coating.
A ninth invention is characterized in that in any one of the first invention to the eighth invention, the bearing case is manufactured by drawing a flat plate.
A tenth invention is characterized in that, in any one of the first invention to the ninth invention, the bearing case is SUP or SUS material or resin.

  According to the present invention, rattle noise generated between the ball screw and the ball screw support bearing or the bearing and the housing can be suppressed, and dimensional change caused by the difference in thermal expansion coefficient between the ball screw support bearing and the housing can also be suppressed. Thus, it is possible to provide an electric power steering apparatus with a small number of parts.

(A) is principal part sectional drawing of the electric-power-steering apparatus based on embodiment of this invention, (b) is a principal part enlarged view of A part of the ball screw support bearing shown by FIG. 1 (a). . (A) is a bearing case in a natural state before incorporating according to an embodiment of the present invention, and (b) is a partial cross-sectional view of a portion B of the bearing case of FIG. 2 (a). It is a perspective view which shows the example of a coating process of the bearing case which concerns on embodiment of this invention. (A) is a perspective view showing a first modified example of the bearing case according to the embodiment of the present invention, and (b) is a perspective view showing a second modified example of the bearing case according to the embodiment of the present invention . It is a perspective view showing the 3rd modification of a bearing case concerning an embodiment of the present invention. (A) And (b) is a perspective view which shows the 4th modification of the bearing case concerning embodiment of this invention.

  Hereinafter, an embodiment of an electric power steering apparatus of the present invention will be described based on the drawings. The present invention is not limited to the present embodiment and can be appropriately designed and changed within the scope of the present invention.

  The rack assist type EPS (R-EPS) of the present embodiment is a type of ball screw type offset rack EPS in which an electric motor is disposed (offset) on a shaft different from the ball screw shaft (rack shaft). The housing 2 for housing the ball screw mechanism, a ball screw support bearing 8 disposed between the housing 2 and the ball screw nut 4 of the ball screw mechanism, and driving of the ball screw nut 4 of the ball screw mechanism. And a ball screw mechanism, and a speed reduction mechanism (not shown) connected to the electric motor. The electric motor and the speed reduction mechanism, which are not illustrated, are not particularly limited and interpreted, and the detailed description will be omitted in the present embodiment.

For example, as shown in FIG. 1A, the ball screw mechanism is provided on a ball screw shaft 6 having a spiral groove 6a formed on the outer peripheral surface, and on the outer periphery of the ball screw shaft 6, and has a spiral groove on the inner peripheral surface. The ball 7 comprises a ball screw nut 4 in which 4a is formed, and a ball 7 disposed in a rolling path formed by the spiral groove 4a of the ball screw nut 4 and the spiral groove 6a of the ball screw shaft 6 The ball screw nut 4 and the ball screw shaft 6 can be moved relative to each other.
That is, for example, the ball screw nut 4 has a cylindrical shape (for example, a cylindrical shape) in which a through hole is formed, and is installed so that the ball screw shaft 6 penetrates the through hole. The steering gear case 3 is provided.

  The spiral groove 6a of the ball screw shaft 6 is formed in a gothic arch shape (a shape combining two circular arcs) over the entire outer peripheral surface length of the ball screw shaft 6 excluding the outer peripheral surface of the rack shaft 5, and the groove R ratio is Is about 0.5. Further, the ball 7 reaching one end of the spiral groove 6a is scooped up by end deflectors (not shown) incorporated at both ends of the ball screw nut 4, passes through the through holes inside the ball screw nut 4 and is spiraled again. It is returned to the groove 6a and circulated again.

  The ball screw nut 4 is rotationally driven by an electric motor (not shown) offset from the ball screw shaft 6 (rack shaft 5), and the balls 7 in the rolling path roll. The ball screw shaft 6 (rack shaft 5) moves in the axial direction.

  The ball screw nut 4 is rotatably supported by a ball screw support bearing 8 accommodated in a bearing accommodation portion (steering gear case) 3.

  The ball screw support bearing 8 is composed of an inner ring 8a integrally formed with the ball screw nut 4 and an outer ring 8c provided outside the inner ring 8a via a ball 8b, and is made of an elastic member provided on the outer ring 8c. It has a structure (floating structure) in which the bearing case 10 floats from the housing 2. That is, the bearing case 10 made of an elastic member is interposed between the outer peripheral surface of the outer ring 8 c of the ball screw support bearing 8 and the housing 2, and the ball screw support bearing 8 is supported in a floating state from the housing 2. Thus, when the ball screw mechanism moves due to vibration or the like, the bearing case 10 serves as a damper that functions as a shock absorbing material. The ball screw mechanism tries to return to the original position by the elastic return force of the bearing case 10 even if it moves.

The bearing case 10 is an elastic member having a predetermined thickness as shown in FIG. 2A, and is provided only on one side of the cylindrical portion 11a, which is the outer peripheral surface of the cylindrical portion, and one side of the cylindrical portion 11a And an annular portion 11b (including a tapered portion 11c) forming a side surface. Then, two bearing cases 10 (bearing case 10a and bearing case 10b) are used so as to face each other (in the figure, the end portions of the cylindrical portion 11a are made to face each other).
Further, in the present embodiment, elastic portions Q (Q1, Q2) are provided at the end portions of the cylindrical portion 11a and the annular portion 11b (including the tapered portion 11c), and as shown in FIG. The bearing case 10 is assembled to the housing 2 in a state where a preload is generated in the annular portion 11b in the elastic portion Q2 of the portion 11b.

The cylindrical portion 11a is an outer peripheral portion of the bearing case 10 in the axial direction, and the cylindrical portion 11a is provided with a plurality of strip-like ribs 11d. By forming the rib 11d in the cylindrical portion 11a, the cylindrical shape is stably maintained.
Further, among the cylindrical portions 11a, a part of the outer peripheral surface P on the end side facing each other is made parallel to the inner peripheral surface of the housing 2 in order to facilitate assembly into the housing 2, and in the radial direction In order to assemble without rattling, a predetermined angle R is provided, and the elastic portion Q1 having a spring function is formed to be inclined toward the end.

  The annular portion 11 b of the bearing case 10 has the same predetermined thickness as the cylindrical portion 11 a and forms the side surface of the bearing case 10. The shape is continuous from one end of the cylindrical portion 11a in a direction perpendicular to the axis (radial direction) to a position covering the side surface of the outer ring 8a of the ball screw support bearing 8 in the axial direction.

Moreover, the taper part 11c which inclines outward (axial direction) is formed in the edge part of the annular part 11b. The tapered portion 11c is pressed from both directions as an elastic portion Q2 having a spring function as shown by an arrow S in FIG. 2B, and is formed in the groove 2a provided in the housing 2 and the groove 20a provided in the spacer 20. It is incorporated in the state which generated pre-pressure.
Specifically, when the ball screw support bearing 8 is incorporated (accommodated) in the bearing accommodation portion (steering gear case) 3, as shown in FIG. 1 (b), the bearing case 10 (10a) of the right side The tapered portion 11c continuous from the annular portion 11b is pressed from the stepped portion 2b of the housing 2 along the groove 2a provided in the housing 2 to make surface contact, and then the annular portion 11b of the left bearing case 10 (10b) Structure in which the tapered portion 11c is pressed from both directions by inserting the spacer 20 so as to generate a pre-load and make surface contact along the groove portion 20a provided in the spacer 20 by making the tapered portion 11c continuous from the above into a surface contact. It has become.

  When the bearing case 10 having such a structure is housed in the bearing housing portion (steering gear case) 3, rattling due to the gap between the housing 2 and the ball screw support bearing 8 is suppressed, and vibration or the like is caused. When the ball screw mechanism moves, the bearing case 10 is deformed to serve as an elastic member that absorbs the movement of the ball screw mechanism.

  The material of the bearing case 10 may be SUP (Steel Use Spring) material which is a spring steel material, SUS (Steel Special Use Stainless) material, resin and the like, and it can be easily manufactured by drawing flat plates of these materials. it can.

Further, in the rack assist type EPS (R-EPS) of the present embodiment, the bearing case 10 is assembled to the bearing accommodation portion (steering gear case) 3 in a state of being incorporated in and integrated with the ball screw support bearing 8. FIG. 1B shows a state in which the bearing case 10 is incorporated in the bearing accommodation portion (steering gear case) 3. Hereinafter, it demonstrates using FIG. 1 (a), (b).
Hold the ball screw support bearing 8 so that the ends of the cylindrical portions 11a of the pair of bearing cases 10a and 10b face each other from both sides (right and left sides in the figure) of the ball screw support bearing 8, and contact the outer ring 8c. The support bearing 8 and the bearing case 10 are integrated.

In the assembly here, a part of the outer peripheral surface P of the cylindrical portion 11a shown in FIG. 2B is parallel to the inner peripheral surface of the housing 2 and an elastic part Q1 provided with a predetermined angle R. The shape is held as it is as shown in FIG. 1 (b). For this reason, the assembly is performed in a state where the gap (space) between the ball screw support bearing 8 and the housing 2 is larger than the thickness of the cylindrical portion 11a.
That is, it is characterized in that the axial contact width M between the cylindrical portion 11 a and the housing 2 is smaller than the axial width N of the ball screw support bearing 8. As described above, by making the contact width between the housing 2 and the bearing case 10 local (small) compared to the bearing width, it is possible to prevent a prick due to the influence of an inclination or the like, the ball screw mechanism It becomes easy to float (become easy to move).

  When the bearing case 10 is assembled integrally with the ball screw support bearing 8, a predetermined gap T (margin) is provided in advance between the bearing case 10a and the end of the cylindrical portion 11a of the bearing case 10b. (Refer to FIG. 1 (b).). Thereby, even if the bearing case 10 is incorporated in the bearing accommodating portion (steering gear case) 3 and there is a gap T even if it is sandwiched and pressed between the housing and the outer ring 8C, the bearing cases 10 with each other (the bearing case 10a and the bearing case 10b) is avoided to touch. The clearance T is incorporated in a state where the cylindrical portion 11a with the bearing case 10 maintaining the shape of the elastic portion Q1 is held between the housing and the outer ring 8C without being pressed against the housing 2, but When the cylindrical portion 11a is sandwiched and pressed by the housing and the outer ring 8C due to vibration from the road surface later, the gap T becomes smaller than that before being incorporated into the bearing housing portion (steering gear case) 3 (FIG. a), (b)).

  In the present embodiment, the bearing positioning portion 12 abuts against the inner peripheral surface of the housing 2 facing the ball screw support bearing 8 via the bearing case 10 so that the ball locates at a position abutted against the inner peripheral surface. The screw support bearing 8 can be positioned.

  Further, the bearing positioning portion 12 positions the ball screw support bearing 8 in a direction perpendicular to the axis (radial direction), and also has a tightening margin in the dimensions of the outer peripheral surface of the bearing case 10 and the outer ring 8c of the ball screw support bearing 8. There is provided an alternative portion 13. As described above, by providing an interference in the dimensions of the ball screw support bearing 8 and the bearing case 10, it is possible to prevent the bearing case 10 from coming off the ball screw support bearing 8.

  Furthermore, since the ball screw shaft 6, the ball screw nut 4, the ball screw support bearing 8 and the bearing case 10 are integrally assembled, they are incorporated into the bearing accommodating portion (steering gear case) 3, so the number of parts and assembly man-hours Can be reduced.

  Further, in the present embodiment, a gap 3a is provided between the annular portion 11b of the ball screw support bearing 8 and the housing 2 on one bearing case 10a side, and a ball screw support bearing is provided on the other bearing case 10b side. A gap 3 b is provided between the annular portion 11 b and the spacer 20.

  Thus, by setting the gaps 3a and 3b, when the bearing case (ball screw mechanism) 10 moves due to the vibration from the road surface traveling the gap, the movement of the ball screw mechanism due to the vibration is absorbed. And can suppress rattle noise.

  The tapered portion 11c of the end of the annular portion 11b of the bearing case 10 is pinched and crushed between the ball screw support bearing 8 and the housing 2 or the spacer 20 when the ball screw support bearing 8 moves in the axial direction. In order to prevent this, grooves 2a and 20a are provided in the housing 2 and the spacer 20, the tapered portion 11c of one bearing case 10a is fixed to the groove 2a of the housing 2, and the tapered portion 11c of the other bearing case 10b is The groove 20 a of the spacer 20 is fixed.

  Thus, by providing the groove portions 2a and 20a in the housing 2 and the spacer 20 and fixing the tapered portions 11c and 11c to the groove portions 2a and 20a, the inner ring 8a of the ball screw support bearing 8 contacts the bearing cases 10a and 10b. To prevent.

As described above, with the bearing case 10 incorporated into the ball screw support bearing 8 and integrated, the ball screw support bearing 8 that is incorporated into the bearing accommodation portion (steering gear case) 3 and causes rattling noise By floating the housing 2 from the housing 2 (floating structure), the ball screw support bearing 8 can be supported so as to be axially movable without directly contacting the housing 2 and without rattling.
The reaction force transmitted from the road surface can be absorbed (buffered), and the rattle noise generated from the ball 8 b and the ball screw support bearing 8 supporting the ball can be suppressed.
Further, since the ball screw support bearing 8 and the bearing case 10 can be assembled in the bearing accommodating portion (steering gear case) 3 in the assembled state, the number of parts and the number of assembling steps can be reduced.

  Further, by mounting the bearing case 10, it is possible to suppress the generation of a gap resulting from the difference in the thermal expansion coefficient between the outer ring 8c of the ball screw support bearing 8 and the housing 2. That is, the dimensional change to the ball screw support bearing 8 due to the temperature change can be absorbed.

  Next, an example in which a soundproof coating is disposed on the bearing case 10 according to the embodiment of the present invention will be described. A soundproofing member is disposed between the housing 2 and at least one of the bearing case 10 and the housing 2. Specifically, in the axial direction positioning portion 12 of the bearing case 10 enclosed by the symbol C in FIG. 1 (b), both the bearing case 10 and the other (housing 2) side, or at least one of Fireproofing is applied with a rubber-based coating or a soundproof member made of an elastic material such as an adhesive.

Further, FIG. 3 shows a case where the entire circumferential surface of the annular portion 11b of the bearing case 10 is coated with rubber. As a coating material as a soundproof member, an elastic material such as a resin, a (foamed) rubber-based material or an adhesive material is suitable as described above.
As a result, the bearing case (ball screw mechanism) 10 is moved by vibration from the road surface during traveling, and soundproofing and vibration isolation of contact noise when contacting the other (housing 2) side can be realized. The coating is not necessarily required on the entire circumferential surface, and even if only a part of the coating is required, soundproofing and antivibration effects can be expected.

[Other modification]
The modification which provided the elastic-modulus change part which changes the elastic modulus of bearing case 10 is demonstrated using figures. In the following description, only the structural parts different from the above embodiment will be described, and the redundant description will be omitted. Further, in the drawings, the same reference numerals are given to the common reference numerals of the bearing case 10.

In the first modification, as shown in FIG. 4 (a), the annular portion 11b of the bearing case 10 has a hole portion 14 (elastic modulus changing portion) in which a substantially rectangular R-shaped square is formed. By providing four at equal intervals, the elastic modulus in the axial direction can be changed. As described above, the soundproof coating may be disposed on the annular portion 11 b of the bearing case 10.
In the second modification, as shown in FIG. 4 (b), the holes 15 (elastic modulus changing portions), which are substantially rectangular in the cylindrical portion 11 a and whose square is processed into an R shape (cut corners), are equally spaced. By providing each of them, the elastic modulus in the direction perpendicular to the axis (radial direction) can be changed.
The number of elastic modulus changing portions of the hole 14 and the hole 15 is not limited to four and it may be plural at equal intervals, and the shapes and phases of the hole 14 and the hole 15 are also limited. I will not. As described above, the soundproof coating may be disposed on the annular portion 11 b of the bearing case 10.

In the third modification, as shown in FIG. 5, 12 holes 16 (elastic modulus changing portions) are formed at equal intervals by cutting both ends of the cylindrical portion 11 a and the annular portion 11 b of the bearing case 10. By providing it, the elastic modulus in the axial direction and in the direction perpendicular to the axis (radial direction) can be changed.
The number of elastic modulus change portions of the hole 16 is not limited to twelve, and a plurality of holes may be provided at equal intervals, and the shape and phase of the hole 16 are not limited. As described above, the soundproof coating may be disposed on the annular portion 11 b of the bearing case 10.

In the fourth modification, as shown in FIGS. 6A and 6B, the thickness is partially formed in a substantially rectangular shape continuously from the cylindrical portion 11a of the bearing case 10 to the annular portion 11b (excluding the tapered portion 11c). The thin-walled part (elastic modulus change part) 17 on the outer peripheral surface side of the bearing case 10 or the thin-walled part (elastic modulus change part) 18 on the inner peripheral surface side of the bearing case 10 By providing eight pieces, the elastic modulus in the axial direction and the direction perpendicular to the axis (radial direction) can be changed (FIG. 6A is a perspective view of the outside of the bearing case 10, FIG.6 (b) is a perspective view of the inner side of bearing case 10.).
The thin-walled portion (elastic modulus changing portion) 17 or the thin-walled portion (elastic modulus changing portion) 18 processed to be thin in thickness is formed on both the cylindrical portion 11a and the annular portion 11b or in the cylindrical portion 11a or the annular portion 11b. Only the outer peripheral surface or the inner peripheral surface may be one side.
Further, the number of elastic modulus changing portions of the thin portion 17 or the thin portion 18 is not limited to eight, and plural elastic portions may be provided at equal intervals, and the shape, thickness and phase of the holes are not limited. As described above, the soundproof coating may be disposed on the annular portion 11 b of the bearing case 10.

  As described above, the change in elastic modulus can be adjusted by incorporating at least one of the cylindrical portion 11a and the annular portion 11b in a bearing case having an elastic modulus changing portion in which the elastic modulus changes. As a result, it is possible to flexibly absorb and reduce rattling noise generated by the ball screw support bearing 8 itself and backlash between the ball screw support bearing 8 and the housing 2.

1 housing cover 2 housing 3 bearing housing (steering gear case)
4 Ball screw nut 5 Rack shaft 6 Ball screw shaft 7 Ball 8 Ball screw support bearing 10 Bearing case 11a Cylindrical part 11b Annular part 11c Taper part 11d Circumferential groove 12 Bearing positioning part 13 Tightening parts 14, 15, 16 Holes ( Elastic modulus change part)
17, 18 Thin section (elastic modulus change section)

Claims (10)

A ball screw shaft having a spiral groove formed on an outer peripheral surface, a ball screw nut provided on an outer periphery of the ball screw shaft and having a spiral groove formed on an inner peripheral surface, a spiral groove of the ball screw nut and the ball screw A ball screw mechanism comprising a ball disposed in a rolling path formed by a helical groove of a shaft;
A housing for housing the ball screw mechanism;
A ball screw support bearing disposed between the housing and the ball screw nut;
And an electric motor disposed on a separate shaft from the ball screw shaft and used to drive the ball screw nut,
Between the ball screw support bearing and the housing, there is provided a bearing case comprising a cylindrical portion and an annular portion continuously provided radially inward from one end of the cylindrical portion. Distributed,
An elastic portion is provided at the end of the cylindrical portion and the annular portion,
The electric power steering apparatus, wherein the bearing case is assembled to the housing in a state where a preload is generated in an elastic portion of the annular portion.   The electric power steering apparatus according to claim 1, wherein an axial contact width between the cylindrical portion of the bearing case and the housing is smaller than an axial width of the ball screw support bearing.   The electric power steering apparatus according to claim 2, wherein the ball screw support bearing is positioned by the annular portion of the bearing case.   The electric power steering apparatus according to any one of claims 1 to 3, wherein at least one of the cylindrical portion and the annular portion has an elastic modulus changing portion in which an elastic modulus changes.   The electric power steering apparatus according to claim 4, wherein the elastic modulus changing portion is a hole or a thin portion.   The electric power steering apparatus according to any one of claims 1 to 5, wherein a soundproof member is disposed between the housing and the bearing case and at least one of the bearing case and the housing. .   The electric power steering apparatus according to claim 6, wherein the soundproof member is made of resin, rubber or adhesive.   The electric power steering apparatus according to claim 7, wherein the soundproofing member is disposed by coating.   The electric power steering apparatus according to any one of claims 1 to 8, wherein the bearing case is manufactured by drawing a flat plate.   The electric power steering apparatus according to any one of claims 1 to 9, wherein the bearing case is SUP or SUS material or resin.

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