BEARING DESIGN AND ENGINE

Abstract

Bearing structure (51) which includes the following: a bearing (43) rotatably supports a rotating shaft extending in an axial direction, wherein the bearing (43) has an outer circumferential surface (43b) with a curved surface (43c) projecting outwards in a radial direction from an axial end towards a central part of the axial direction; and a housing (31) having a bearing receiving recess (38) extending in the axial direction to receive and retain the bearing (43), wherein the bearing receiving recess (38) has an inner circumferential surface (53b) with a cylindrical part (54) and a contact part (55), wherein the contact part (55) adjoins the cylindrical part (54) in a circumferential direction, the bearing (43) is located on an inner side of the cylindrical part (54), a radial inner surface of the attachment part (55) projects completely radially inwards from the cylindrical part (54) and the curved surface (43c) of the bearing (43) is in contact with the mounting part (55) at at least three points which are separated from each other in one direction of rotation of the rotating shaft.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a bearing construction and a motor.

[0002] Japanese patent specification JP H11-164510A discloses a motor comprising a bearing assembly with a rotating shaft, a bearing rotatably supporting the rotating shaft, and a housing with a bearing receptacle that receives and retains the bearing. In the motor described in the publication, the motor bearing has a curved outer circumferential surface that curves or projects outward from the axial ends in the radial direction toward the axial center of the bearing. Furthermore, the bearing receptacle has an inner circumferential surface that has a circular cross-section in a direction orthogonal to the axis of the bearing. The curved surface of the bearing is located in a portion of the bearing close to a lower end of the bearing receptacle.The bearing is held in the bearing recess so that the curved surface of the bearing is in contact with the inner circumferential surface of the bearing recess over its entire circumference.

[0003] In the bearing design described above, if the inner circumferential surface of the bearing recess has a large runout error, it will contact the curved surface of the bearing at fewer points, and may only contact the curved surface at three points. Furthermore, the inner circumferential surface of the bearing recess will not contact the curved surface of the bearing at the specified points. In such a case, the position of the bearing relative to the bearing recess will vary between motors. This will displace the rotating shaft supported in the bearing. Therefore, the axis of rotation of the rotating shaft may be located in different positions in different motors.

[0004] Further examples of state of the art include DE 10 2007 057 706 A1, DE 10 2013 200 128 A1, DE 10 2012 216 946 A1 and JP H11 - 18 404 A. BRIEF SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to provide a bearing design and a motor that reduce positional differences of the rotating shaft axis.

[0006] According to the invention, the problem is solved in each case by a bearing construction with the features of claim 1 and claim 2.

[0007] Other aspects and advantages of the invention will become apparent from the following description in conjunction with the accompanying drawings, which illustrate the principle of the invention by way of example. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The invention, together with its tasks and advantages, can best be understood by reference to the following description of the currently preferred embodiments together with the accompanying drawings, in which: Fig. 1 is a partial cross-sectional view showing a motor according to an embodiment of the present invention; Fig. 2A and Fig. 2B End views are of a gearbox housing from Fig. 1 shows that it receives a snail shaft; Fig. 3A and Fig. 3B cross-sectional views are those showing the gearbox housing of Fig. 1 along line 3A-3A in Fig. 4A show; Fig. 4A a front view of the in Fig. 1 shown gearbox housing is; Fig. 4B a partially enlarged view of Fig. 4A is; Fig. 5A and Fig. 5B Cross-sectional views are those showing the gearbox housing of Fig. 1 show; Fig. 6A and Fig. 6B Cross-sectional views are those showing a gearbox housing of a further embodiment along line 6A-6A in Fig. Show 7A; Fig. 7A a front view of a Fig. 6A shown gearbox housing is; Fig. 7B a partially enlarged view of Fig. 7A is and Fig. 8A and Fig. 8B Cross-sectional views are those showing the gearbox housing of Fig. Show 6A. DETAILED DESCRIPTION OF PREFERRED EXECUTION FORMS

[0009] The following describes an embodiment of a motor that has a bearing design.

[0010] One motor 1 of which is in Fig. The present embodiment shown in Figure 1 is a geared motor and comprises a motor body 2 and a reduction drive 3. The reduction drive 3 reduces the rotational speed produced by the motor body 2 and increases the output torque.

[0011] The motor body 2 has a yoke housing 11 (hereinafter referred to as yoke 11) made of a conductive metallic material. The yoke 11 is tubular and has a closed end. The yoke 11 has an open end 11a. The open end 11a has a flange 11b extending from the yoke 11 to the outside. The flange 11b is coupled and fastened by screws 12 to a mounting part 22 of a gear housing (case) 31, which forms the casing of the reduction drive 3.

[0012] Furthermore, a brush holder 13, made of an insulating material such as synthetic resin, is coupled to the open end 11a of the yoke 11 to close the open end 11a. When the yoke 11 is coupled and fastened to the gearbox housing 31 by the screws 12, the brush holder 13 is held and secured between the flange 11b and the mounting part 33.

[0013] Magnets 14 are positioned opposite each other and attached to the inner surface of the yoke 11. A runner 15 is rotatably arranged on the inside of the magnets 14. A basal end (in Fig. 1 (lower end) of a drive shaft (rotary shaft) 16 of the runner 15 is rotatably mounted in a bearing 17 located in the central part of the rear end of the yoke 11. A bearing 18, coupled to the central part of the brush holder 13, supports the distal side of the drive shaft 16 (the section near the distal end or upper end of the drive shaft 16, as shown in Figure 1). Fig. (as seen in Figure 1) rotatable. The distal end of the drive shaft 16 extends through the brush holder 13 in the axial direction and projects into the gearbox housing 31.

[0014] An armature lamination stack 21, radially opposite the magnet 14, is attached to the drive shaft 16 so that the armature lamination stack 21 is rotatable with the drive shaft 16 as a single unit. Windings 22 are wound around the armature lamination stack 21. A commutator 23 is also attached to the drive shaft 16 between the part to which the armature lamination stack 21 is attached and the part mounted in the bearing 18, so that the commutator 23 is rotatable with the drive shaft 16 as a single unit. Segments 23a are arranged circumferentially on the outer circumferential surface of the commutator 23. All or some of the segments 23a are electrically connected to the winding 22.

[0015] The brush holder 13 carries a power supply brush (not shown) that slides in contact with the segments 23a of the commutator 23. The brush holder 13 also has a connector 13a to which an external connector (not shown) is connected. Current is supplied from the external connector to the power supply brush through terminals (not shown) of the connector 13a.

[0016] The brush holder 13 has positioning holes 13b that are opposite the flange 11b of the yoke 11 in the direction of the axis of rotation L1 of the drive shaft 16. The positioning holes 13b are used for positioning the brush holder 13 and the gearbox housing 31. Each positioning hole 13b extends through the brush holder 13 in the direction of the axis of rotation L1 of the drive shaft 16.

[0017] The reduction drive 3 comprises the gearbox housing 31 and a reduction unit 32, which is housed within the gearbox housing 31. Positioning projections 33a are arranged on the mounting part coupled to the yoke 11 in the gearbox housing 31 at locations corresponding to the positioning holes 13b of the brush holder 13. The positioning projections 33a extend from the mounting part 31 towards the yoke 11 in the direction of the axis of rotation L1 of the drive shaft 16. When the yoke 11 and the gearbox housing 31 are coupled and fastened together by the screws 12, the positioning projections 33a are inserted into the corresponding positioning holes 13b to position the brush holder 13 and the gearbox housing 31 in the direction of rotation and in the radial direction of the drive shaft 16.

[0018] The gearbox housing 31 has a worm shaft mounting part 34 and a wheel mounting part 35. The worm shaft mounting part 34 extends in the direction of the axis of rotation L1 of the drive shaft 16 from the mounting part 33 to the side opposite the yoke 11. The wheel mounting part 35 is located next to the worm shaft mounting part 34 (in Fig. 1 seen on the left) and is integral with the worm shaft mounting part 34.

[0019] The gearbox housing 31 has a connecting recess 36 that extends from the mounting part 33 to the worm shaft receiving part 34. The connecting recess 36 extends from the end face of the mounting part 33, which is opposite the yoke 11, in the direction of the axis of rotation L1 of the drive shaft 16. The connecting recess 36 opens towards the yoke 11. The connecting recess 36 receives the distal side of the drive shaft 16, the commutator 23, and the portion of the brush holder 13 that projects from the flange 11b towards the reduction drive 3.

[0020] The gearbox housing 31 has a clutch receiving recess 37 extending from the central part of the rear end of the connecting recess 36 in the direction of the axis of rotation L1 of the drive shaft 16 to the side opposite the yoke 11. Furthermore, the gearbox housing 31 has a bearing receiving recess 38 extending from the central part of the rear end of the clutch receiving recess 37 to the side opposite the yoke 11 in the direction of the axis of rotation L1 of the drive shaft 16. Additionally, the gearbox housing 31 has a worm shaft receiving recess 39 extending from the rear end of the bearing receiving recess 38 to the side 11 opposite the yoke 11 in the direction of the axis of rotation L1 of the drive shaft 16. The worm shaft receiving recess 39 is located in the worm shaft receiving part 34. The wheel receiving part 35 has a wheel receiving recess 40 which communicates with the worm shaft receiving recess 39.The wheel mounting recess 40 is in communication with the worm shaft mounting recess 39 on the axial central part of the worm shaft mounting recess 39.

[0021] The worm shaft receiving recess 39 accommodates a worm shaft 41 (rotating shaft or driven shaft) such that the worm shaft 41 is coaxial with the drive shaft 16, that is, so that the axis of rotation L1 of the drive shaft 16 is aligned with the axis of rotation L2 of the worm shaft 41. Furthermore, the worm shaft receiving recess 39 accommodates a thrust plate 42, which absorbs the axial force of the worm shaft 41. The thrust plate 42 lies against a distal end face (upper end face in Fig. 1) opposite the worm shaft 41 in the axial direction. A basal part of the worm shaft 41 (part near the basal end or lower end of the worm shaft 41, as in Fig. (as shown in Figure 1) is inserted into the bearing 32 received in the bearing recess 38 and rotatably mounted there. Furthermore, the distal end of the worm shaft 41 is rotatably mounted in a bearing 44, which is located in the worm shaft receiving recess 39 at a distal end (upper end, as shown in Figure 1). Fig. (as shown in Figure 1) is arranged in the worm shaft receiving part 34. The basal end of the worm shaft 41 extends through the bearing 43 into the connecting recess 36. A coupling 45, extending from the connecting recess 36 to the coupling receiving recess 37, couples the basal end of the worm shaft 41 to the distal end of the drive shaft 16. When the drive shaft 16 is rotated, the coupling 45 transmits the rotation of the drive shaft 16 to the worm shaft 41. When the drive shaft 16 is not rotated, the coupling 45 restricts the rotation of the worm shaft 41.

[0022] The worm shaft 41 has a worm 41a, which is a gear element in the form of a screw, between the part mounted in bearing 43 and the part mounted in bearing 44. A worm wheel 46, which engages with the worm part 41a, is rotatably arranged in the wheel mounting recess 40. The reduction unit 32 has the worm wheel 46, which is circular, and the worm shaft 41. The radial central part of the worm wheel 46 has an output shaft (not shown) that extends in the direction of the axis of rotation L3 of the worm wheel 46 and is integrally rotatable with the worm wheel 46. The output shaft is angled on one side in the direction of the axis of rotation L3 of the worm wheel 46 (the side that extends from the plane of Fig. 1 way extends) from the wheel mounting part 35 in front.

[0023] In the following, a bearing structure 51, which rotatably supports the worm shaft 41, will be described in detail.

[0024] The bearing structure 51 includes the bearing 43, which supports the inserted worm shaft 41, and the part of the gearbox housing 31 which has the bearing receiving recess 38, which receives and holds the bearing 43.

[0025] As in the Fig. 2A and Fig. As shown in Figure 2B, the bearing 43 is tubular and has an inner circumferential surface 43a that has essentially the same diameter as the outer diameter of the basal part of the worm shaft 41. The outer circumferential surface 43b of the bearing 43 has curved surfaces 43c at its two axial ends. Each curved surface 43c bulges or projects radially outward from the axial end of the bearing 43 toward the axial center of the bearing 43. Furthermore, each curved surface 43c extends around the entire circumference of the bearing 43 to form an annular shape. The portion of the outer circumferential surface 43b of the bearing 43 that lies axially between the two curved surfaces 43c is cylindrical and has a fixed diameter.

[0026] As in the Fig. 3A and Fig. As shown in Figure 3B, the bearing receiving recess 38 has a first receiving recess 52 extending from the central part of the rear end of the coupling receiving recess 37, and a second receiving recess 53 extending from the central part of the rear end of the first receiving recess 52. The first receiving recess 52 extends from the central part of the rear end of the coupling receiving recess 37 to the distal end of the worm shaft receiving part 34 in the direction of the axis of rotation L2 of the worm shaft 41 (the same direction as the axis of rotation L1 of the drive shaft 16). The second receiving recess 53 extends from the central part of the rear end of the first receiving recess 52 in the direction of the axis of rotation L2 to the worm shaft receiving recess 39. The worm shaft receiving recess 39 extends from the rear end of the second receiving recess 53 in the direction of the axis of rotation L2 of the worm shaft 41.The second receiving recess 53 connects the first receiving recess 52 with the worm shaft receiving recess 39.

[0027] As in the Fig. 4A and Fig. As shown in Figure 4B, the first receiving recess 52 is circular when viewed in the direction of the axis of rotation L2 of the worm shaft 41. As shown in Fig. As shown in Figure 2B, the inner circumferential surface 52a of the first receiving recess 52 is cylindrical and has a larger inner diameter than the outer diameter of the bearing 43. The depth of the first receiving recess 52 (length in the direction of the axis of rotation L2 of the worm shaft 41) is slightly greater than half the axial length of the bearing 43.

[0028] As in Fig. As shown in Figure 4B, the second receiving recess 53 is circular when viewed in the direction of the axis of rotation L2 of the worm shaft 41. As shown in the Fig. 3B and Fig. As shown in Figure 4B, the inner diameter of the second receiving recess 53 decreases from the opening of the second receiving recess 53 towards the rear end surface 53a of the second receiving recess 53. The second receiving recess 53 has an inner circumferential surface 53b, which has a cylindrical part 54 and (in the present embodiment) several contact elements 55.

[0029] The cylindrical part 54 is cylindrical and extends in the direction of the axis of rotation L2 of the worm shaft 41. The cylindrical part 54 of the present embodiment is chamfered such that the inner diameter of the cylindrical part 54 decreases from the opening of the bearing receiving recess 38 towards the rear end of the bearing receiving recess 38, specifically from the opening of the second receiving recess 53 towards the rear end surface 53a. The cylindrical part 54, which has the shape of a truncated cone, extends from the opening of the second receiving recess 53 to the rear end surface 53a of the second receiving recess 53 in the direction of the axis of rotation L2 of the worm shaft 41. As shown in the Fig. 2B, Fig. 3B and Fig. As shown in Figure 4B, the inner diameter D1 of the cylindrical part 54 is larger than the outer diameter of the bearing 43 at the axial end of the cylindrical part 54, which is close to the opening of the second receiving recess 53. The inner diameter D2 of the cylindrical part 54 is smaller than the outer diameter of the bearing 43 at the axial end of the cylindrical part 54, which is close to the rear end face 53a of the second receiving recess 53. As shown in the Fig. 5A and Fig. As shown in Figure 5B, the axial end of the cylindrical part 54, which is close to the rear end surface 53a of the second receiving recess 53, is located at the outer edge of the rear end surface 53a.

[0030] As in Fig. As shown in Figure 4B, the three contact parts 55 are located at three points in the second receiving recess 53 and are separated from each other in the direction of rotation (circumferential direction) of the worm shaft 41. The three contact parts 55 are designed such that they subdivide the cylindrical part 54 in the circumferential direction. Two of the three contact parts 55 are located, viewed in the direction of the axis of rotation L2 of the worm shaft 41, on the side of the axis of rotation L2 of the worm shaft 41 that is opposite the worm wheel 46. Furthermore, these two contact parts 55 are located on opposite sides of a reference line L4, which is in the Fig. 4A and Fig. As shown in Figure 4B, the two contact parts 55 are equidistant from the reference line L4 when viewed in the direction of the rotational axis L2 of the worm shaft 41. The reference line L4 runs parallel to the radial direction of the worm wheel 46 and orthogonal to the axis of rotation L2 of the worm shaft 41. In the present embodiment, the two contact parts 55 are symmetrical with respect to the reference line L4 when viewed in the direction of the axis of rotation L2 of the worm shaft 41. The remaining contact part 55 lies on the reference line L4 between the axis of rotation L2 of the worm shaft 41 and the axis of rotation L3 of the worm wheel 46 when viewed in the direction of the axis of rotation L2 of the worm shaft 41.This means that the centers of the two contact parts 55 located on the side of the axis of rotation L2 of the worm shaft 41 opposite the worm wheel 46, and of the remaining contact part 55 located between the axis of rotation L2 of the worm shaft 41 and the axis of rotation L3 of the worm wheel 46, are opposite each other in the radial direction of the second receiving recess 53. Furthermore, the cylindrical part 54 is located on opposite sides of each contact part 55 in the circumferential direction (direction of rotation of the worm shaft 41), and each contact part 55 abuts the cylindrical part 54 in the circumferential direction.

[0031] As in the Fig. 4B and Fig. As shown in Figure 5B, the three attachment parts 55 have an identical shape. Each attachment part 55 has a flat surface that is chamfered to project radially inwards from the opening of the bearing receiving recess 38 to the rear end of the bearing receiving recess 38, that is, from the opening of the second receiving recess 53 to the rear end surface 53a. Each attachment part 55 is rectangular. Each attachment part 55 has sides 55a and 55b, which are defined by the two ends in the direction in which the axis of rotation L2 of the worm shaft 41 runs. The sides 55a and 55b of the plant components 55 are such that the sides 55a and 55b are orthogonal to the radial direction of the second receiving recess 53 in the middle of the sides 55a and 55b in the circumferential direction of the second receiving recess 53 (the same as the direction of rotation of the worm shaft 41), as seen from the axis of rotation L2 of the worm shaft 41.

[0032] The center of side 55a, which is close to the rear end surface 53a of the second receiving recess 53, is located at the inner edge of the rear end surface 53a. Side 55b, which is close to the opening of the second receiving recess 53, is located on the radial inner side of the cylindrical part 54 in the opening of the second receiving recess 53. Each contact part 55 therefore projects completely radially inward from the cylindrical part 54.

[0033] As in Fig. As shown in Figure 2B, the bearing 43 is inserted into the bearing receiving recess 38 such that the axial direction of the bearing receiving recess 38 corresponds to the axial direction of the bearing 43. One axial end of the bearing 43 is located in the second receiving recess 53 (i.e., the inside of the cylindrical part 54), and the other axial end of the bearing 43 is located in the first receiving recess 52. As shown in the Fig. 2B and Fig. As shown in Figure 4B, the three contact elements 55 are in contact with the curved surface 43c on the rear end side (curved surface 43c, which is close to the rear end face 53a of the second receiving recess 53). More specifically, the contact elements 55 are located at three points that are spaced apart from each other in the direction of rotation of the worm shaft 41. The curved surface 43c on the rear end side is in contact with the contact elements 55 at three points that are separated in the direction of rotation of the worm shaft 41. The three contact elements 55 support the bearing 43.

[0034] A retaining spring 56 is arranged between the curved surface 43c of the open end (curved surface 43c of the bearing 43, which is close to the opening of the first receiving recess 52) and the inner circumferential surface 52a of the first receiving recess 52. The retaining spring 56 pre-tensions the bearing 43 towards the rear end surface 53a of the second receiving recess 53 and limits the separation of the bearing 43 from the bearing receiving recess 38.

[0035] The following describes the functionality of the present embodiment.

[0036] In engine 1, referring to Fig. 1. The rotor generates a rotating magnetic field that drives and rotates the rotor 15 (drive shaft 16) when current is supplied through the terminals and the power supply brush from the external connector connected to connector 13a. The rotation of the drive shaft 16 is transmitted to the worm shaft 41 via the coupling 45. The rotational speed transmitted to the worm shaft 41 is reduced by the worm shaft 41 and the worm wheel 46 and then output by the output shaft.

[0037] As in the Fig. 2B and Fig. As shown in Figure 4B, the bearing assembly 51 of the motor 1 has contact elements 55 which project radially inwards from the cylindrical part 54 at three points separated in the direction of rotation of the worm shaft 41. The three contact elements 55 are positively engaged with the curved surface 43c on the rear end side.

[0038] In motor 1, the distal part of the drive shaft 16 is supported in the bearing 18, which is held by the brush holder 13. The worm shaft 41 is supported in the bearings 43 and 44, which are held by the gearbox housing 31. The positioning projections 33a of the gearbox housing 31 therefore engage in the positioning holes 13b of the brush holder 13 to align the drive shaft 16 and the worm shaft 41 with each other.

[0039] The present embodiment has the advantages described below. (1) The contact elements 55 project radially inward from the cylindrical part 54. Therefore, the contact elements 55 slightly contact the curved surface 43c on the rear end side. The curved surface 43c on the rear end side contacts the contact elements 55 at three points separated from each other in the direction of rotation of the worm shaft 41. Since the inner circumferential surface of the bearing recess 38 slightly contactes the curved surface 43c on the rear end side at defined points, differences in the position of the bearing 43 relative to the bearing recess 38 are reduced. Accordingly, differences in the position of the axis of rotation L2 of the worm shaft 41, which is rotatably mounted in the bearing 43, are reduced, even if the cylindrical part 54 has a large runout error. (2) Each mounting element 55 is chamfered to project radially inward from the opening of the bearing receiving recess 38 toward the rear end of the bearing receiving recess 38, that is, from the opening of the second receiving recess 53 toward the rear end face 53a. This makes it possible to easily change the position of the bearing 43 in the bearing receiving recess 38 and allows for easy alignment of the bearing 43. Furthermore, the simple, flat shape of each mounting element 55 allows the bearing receiving recess 38 to have a simple shape. This also facilitates the casting of the gearbox housing 31, which incorporates the mounting elements 55, and the machining for forming the mounting elements 55. The mounting elements 55 are therefore easy to manufacture. (3) The motor 1 has two rotating shafts, namely the drive shaft 16 and the worm shaft 41, to which the rotation of the drive shaft 16 is transmitted. Such a motor requires that the drive shaft 16 and the worm shaft 41 are precisely aligned with each other. In the present embodiment, the bearing assembly 51 of the motor effectively limits the inclination of the axis of rotation L2 of the worm shaft 41, which is supported in the bearing assembly 51. This increases the alignment accuracy of the worm shaft 41. (4) The worm shaft 41 receives a thrust force from the worm wheel 46 in the radial direction of the worm wheel 46, that is, in the direction orthogonal to the axis of rotation L2 of the worm shaft 41. The bearing 43, which rotatably supports the worm shaft 41, receives the same thrust force from the worm shaft 41. Two of the contact parts 55 are located opposite the worm wheel 46 with respect to the axis of rotation L2 of the worm shaft 41, viewed in the direction of the axis of rotation L2 of the worm shaft 41. Furthermore, the two contact parts 55 are located on opposite sides of the reference line L4 and are equidistant from the reference line L4, which is parallel to the radial direction of the worm wheel 46 and orthogonal to the axis of rotation L2 of the worm shaft 41. The inner circumferential surface 53b of the second receiving recess 53 therefore effectively supports the bearing 43, which receives the thrust force from the worm gear 46, with the three contact parts 55 including the two contact parts 55 above.Accordingly, the bearing 43 is held stably in the bearing receiving recess 38 when the worm shaft 41 rotates, while alignment errors of the bearing 43 in relation to the bearing receiving recess 38 are limited. (5) The second receiving recess 53 is designed such that its inner diameter decreases from the opening towards the rear end surface 53a. The cylindrical part 54, which forms the inner circumferential surface 53b of the second receiving recess 53, is chamfered so that its inner diameter decreases from the opening of the second receiving recess 53 towards the rear end surface 53a. Each of the contact elements 55, which form the inner circumferential surface 53b of the second receiving recess 53 with the cylindrical part 54, has a flat surface that is chamfered radially inwards from the opening of the second receiving recess 53 towards the rear end surface 53a. Accordingly, the position of the bearing 43 in the direction of the axis of rotation L2 of the worm shaft 41 can be easily changed by changing the inclination angle of the cylindrical part 54 and the contact elements 55. (6) The distal part of the drive shaft 16 is supported in the bearing 18, which is held by the brush holder 13. The worm shaft 41 is supported in the bearings 43 and 44, which are held by the gearbox housing 31. Inserting the positioning projections 33a of the gearbox housing 31 into the positioning holes 13b of the brush holder 13 therefore aligns the drive shaft 16 and the worm shaft 41 with each other. Accordingly, the positioning projections 33a must be formed in precise positions. A reference pin can be inserted into the bearing 43 and the worm shaft receiving recess 39 to perform a dimensional check that measures the positional accuracy of the positioning projections 33a. In the dimensional check, the positional accuracy of the positioning projections 33a is measured using the distance from the axis of the reference pin to each positioning projection 33a of the gearbox housing 31.The present embodiment limits alignment errors of the bearing 43 relative to the bearing receiving recess 38. This limits the inclination of the reference pin axis relative to the axial direction in the gearbox housing 31. Accordingly, measurement errors that would result from the inclination of the reference pin are limited during dimensional inspection using the reference pin. This reduces the number of modifications and inspections performed on a mold forming the gearbox housing and reduces the number of operations and the time required to manufacture the mold for the gearbox housing 31.

[0040] It should be obvious to a person skilled in the art that the present invention can be implemented in many other specific forms without deviating from the meaning and scope of the invention. Specifically, it should be understood that the present invention can be implemented in the following forms.

[0041] In the embodiment described above, each contact part 55 has a flat surface that is chamfered to project radially inward from the opening of the bearing receiving recess 38 to the rear end of the bearing receiving recess 38. However, each contact part 55 need not have a flat surface, as long as the contact part 55 has the section that projects radially inward from the cylindrical part 54. For example, the contact part 55 can have a curved surface that projects further radially inward as it approaches the axial center section. In such a case, the entire contact part 55 can project radially inward from the cylindrical part 54 in the axial direction. Alternatively, only the axial center section of the contact part 55 can project radially inward from the cylindrical part 54.

[0042] The number of contact elements 55 of the bearing receiving recess 38 and the number of positions of the contact elements 55 in the bearing receiving recess 38 are not limited to the description above. The number of contact elements 55 can be one or more, as long as the curved surface 43c on the rear end side is in contact with the contact elements 55 at at least three points. If the bearing receiving recess 38 has several contact elements 55, the contact elements 55 can be displaced in the direction of rotation of the worm shaft 41.

[0043] In the Fig.In the example shown in Figures 6A to 8B, the inner circumferential surface 53c of the second receiving recess 53 has the cylindrical part 54 and eight contact elements 55. The eight contact elements 55 are spaced at equal intervals (45° in this example) in the direction of rotation of the worm shaft 41. This causes the inner circumferential surface 53c of the second receiving recess 53 to contact the curved surface 43c of the bearing 43 at eight points, which are spaced at equal intervals in the direction of rotation of the worm shaft 41. That is, the bearing receiving recess 38 supports the curved surface 43c of the bearing 43 at the eight points, which are spaced at equal intervals in the direction of rotation of the worm shaft 41. The bearing 43 thus receives a thrust force uniformly in the axis of rotation L2 of the worm shaft 41 at the eight points where the curved surface 43c of the bearing 43 is in contact with the inner circumferential surface 53c of the second receiving recess 53.This further limits alignment errors of the bearing 43 relative to the bearing recess 38. Accordingly, differences in the position of the axis of rotation L2 of the worm shaft 41 are further reduced. Furthermore, if the gearbox housing 31 is made of resin, sink marks are reduced during the casting of the components.

[0044] In the embodiment above, the curved surface 43c of the bearing 43 is in contact with each mounting part 55 at a single point. However, the curved surface 43c can be in contact with each mounting part 55 at multiple points.

[0045] In the above embodiment, the curved surface 43c of the bearing 43 is annular and extends over the entire circumference of the bearing 43. However, the curved surface 43c of the bearing 43 need not be annular and extend over the entire circumference of the bearing 43, as long as the curved surface 43c is in contact with the bearing elements 55.

[0046] In the embodiment above, the cylindrical part 54 is chamfered so that its inner diameter decreases from the opening of the bearing receiving recess 38 to the rear end of the bearing receiving recess 38, that is, from the opening of the second receiving recess 53 to the rear end surface 53a. However, the cylindrical part 54 need not be shaped in this way. The cylindrical part 54 can have the shape of a cylinder (including a shape that is subdivided circumferentially at the contact parts 55) so that the bearing 43 is arranged within the cylindrical part 54. That is, the cylindrical part 54 can be cylindrical to surround the outer circumference of the bearing 43 with the contact parts 55.For example, the cylindrical part 54 can be cylindrical (including a shape that is subdivided in the circumferential direction at the mounting parts 55) and have a fixed inner diameter from the opening of the bearing receiving recess 38 to the rear end of the bearing receiving recess 38.

[0047] The bearing assembly 51 of the above embodiment can rotatably support at least one of the basal end of the drive shaft 16 (part supported in bearing 17), the distal end of the drive shaft 16 (part supported in bearing 18), and the distal end of the worm shaft 41 (part supported in bearing 44). In such a case, the bearing receiving recess 38, which receives and holds the bearing 43, need not have any contact elements 55.

[0048] In the embodiment described above, the drive shaft 16 and the worm shaft 41 are separate and coupled by the coupling 45. However, the drive shaft 16 and the worm shaft 41 can also be integrated together.

[0049] In the embodiment above, the motor 1 is a geared motor in which the reduction drive 3 is coupled to the motor body 2. However, the motor 1 does not necessarily have to include the reduction drive 3.

[0050] In the embodiment described above, the motor 1 has the bearing assembly 51. However, the bearing assembly 51 is applicable to a device other than the motor, in which a rotating shaft is rotatably mounted in a bearing that is received in a bearing recess of a housing.

[0051] The present examples and embodiments are to be regarded as illustrative and not limiting, and the invention is not to be limited to the details given herein, but may be modified within the content and equivalence of the attached claims.

Claims

Bearing construction (51) comprising: a bearing (43) rotatably supporting a rotating shaft extending in an axial direction, wherein the bearing (43) has an outer circumferential surface (43b) with a curved surface (43c) projecting outwards in a radial direction from an axial end towards a central part of the axial direction;and a housing (31) having a bearing receiving recess (38) extending in the axial direction to receive and retain the bearing (43), wherein the bearing receiving recess (38) has an inner circumferential surface (53b) with a cylindrical part (54) and a contact part (55), wherein the contact part (55) adjoins the cylindrical part (54) in a circumferential direction, the bearing (43) is located on an inner side of the cylindrical part (54), a radial inner surface of the contact part (55) projects completely radially inward from the cylindrical part (54), and the curved surface (43c) of the bearing (43) is in contact with the contact part (55) at least three points that are separated from each other in a direction of rotation of the rotating shaft. Bearing construction (51) comprising: a bearing (43) rotatably supporting a rotating shaft extending in an axial direction, wherein the bearing (43) is designed as a radial bearing, and wherein the bearing (43) has an outer circumferential surface (43b) with a curved surface (43c) projecting outwards in a radial direction from an axial end towards a central part of the axial direction; and a housing (31) having a bearing receiving recess (38) extending in the axial direction to receive and retain the bearing (43), wherein the bearing receiving recess (38) has a first receiving recess (52) and a second receiving recess (53), the first receiving recess (52) having a cylindrical inner circumferential surface (52a) with a constant inner diameter, wherein the inner circumferential surface (52a) extends from one end of the bearing receiving recess (38) to the second receiving recess (53),the second receiving recess (53) has a rear end surface (53a) and an inner circumferential surface (53b), wherein the inner circumferential surface (53b) is chamfered such that the inner diameter of the inner circumferential surface (53b) decreases from the first receiving recess (52) to the rear end surface (53a), the inner circumferential surface (53b) of the second receiving recess (53) has a cylindrical part (54) and a contact part (55), wherein the contact part (55) adjoins the cylindrical part (54) in a circumferential direction, the bearing (43) is located on an inner side of the cylindrical part (54), a radial inner surface of the contact part (55) projects completely radially inward from the cylindrical part (54), and the curved surface (43c) of the bearing (43) is in contact with the contact part (55) at at least three points, which are separated from each other in a direction of rotation of the rotating shaft. is., Bearing construction (51) according to claim 1 or 2, wherein the support part (55) is one of several support parts (55) and the support parts (55) are spaced apart at equal intervals in the direction of rotation of the rotating shaft. Bearing construction (51) according to one of claims 1 to 3, wherein the mounting part (55) has a flat surface which is chamfered to project radially inwards from an opening of the bearing receiving recess (38) to a rear end of the bearing receiving recess (38). Motor (1) comprising: the bearing assembly (51) according to any one of claims 1 to 4; a drive shaft (16) which is rotated; and a driven shaft (41) onto which the rotation of the drive shaft (16) is transmitted, wherein the driven shaft (41) is arranged coaxially with the drive shaft (16), wherein the drive shaft (16) and / or the driven shaft (41) functions as the rotating shaft and the bearing assembly (51) rotatably supports the drive shaft (16) and / or the driven shaft (41). Motor (1) comprising: the bearing assembly (51) according to claim 1 or 2; a worm shaft (41) and a worm wheel (46) engaging with the worm shaft (41), wherein the bearing assembly (51) rotatably supports the worm shaft (41); the contact part (55) is one of several contact parts (55); the contact parts (55) are arranged at locations separated from each other in a direction of rotation of the shaft; two of the contact parts (55), viewed in an axial direction of the worm shaft (41) with respect to an axis (L2) of the worm shaft (41), are located on a side opposite the worm wheel (46); the two contact parts (55) are located on opposite sides of a reference line (L4) and are equidistant from the reference line (L4); and the reference line (L4) extends in a direction parallel to a radial direction of the worm wheel (46). and is orthogonal to the axis (L2) of the worm shaft (41).

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