ELECTRIC MOTOR

Abstract

An electric motor contains a motor shaft which is arranged in a motor housing. The motor shaft is rotatably mounted about a rotational axis in at least one rolling or ball bearing, which sits in a bearing receiving area and contains an outer ring and an inner ring fixed to the motor shaft. The outer ring of the rolling bearing is pretensioned by a spring disc which sits in the bearing receiving area and has a number of wave trains with alternatingly axially projecting half wave trains, and the spring disc has a number of centering elements on the inner circumference. The centering elements rest against the motor shaft when the spring disc is untensioned and is arranged at a distance to the motor shaft when the spring disc is tensioned.

Claims

1. An electric motor, comprising: a stator; a motor shaft; a motor housing; at least one roller bearing with an outer ring and an inner ring; a rotor disposed non-rotatably on said motor shaft and further disposed in said motor housing, said rotor being mounted so that it can move in rotation about an axis of rotation in said at least one rolling bearing with said inner ring fixed to said motor shaft; a bearing retainer, said at least one rolling bearing disposed in said bearing retainer; and a spring washer, said outer ring of said rolling bearing being pretensioned by means of said spring washer sitting in said bearing retainer, said spring washer having an annular washer body with, in a circumferential direction of said spring washer, a plurality of wave trains with alternatingly axially flared half-wave trains, and said spring washer having, at an inner circumference of said annular washer body, a plurality of radially inward directed centering elements bearing against said motor shaft when said spring washer is untensioned and are spaced apart from said motor shaft in a tensioned state of said spring washer.

2. The electric motor according to claim 1, further comprising an annular tension washer, wherein said spring washer is pretensionable or is pretensioned by means of said annular tension washer which is inserted in said bearing retainer in a form-locking and/or force-locking manner.

3. The electric motor according to claim 2, wherein said annular tension washer has a shaft opening formed therein and, configured as a passage, for said motor shaft.

4. The electric motor according to claim 3, wherein said annular tension washer has a washer outer edge which is flared axially.

5. The electric motor according to claim 1, wherein said radially inward directed centering elements each have a radial web integrally formed on said inner circumference of said annular washer body.

6. The electric motor according to claim 5, wherein said radially inward directed centering elements each have a centering section in a shape of an arc of a circle.

7. The electric motor according to claim 6, wherein said centering section in the shape of the arc of the circle is integrally formed on said radial web on a web end facing away from said inner circumference of said annular washer body.

8. The electric motor according to claim 5, wherein said radially inward directed centering elements are disposed on said alternatingly axially flared half-wave trains, flared axially in a same axial direction, of said annular washer body of said spring washer.

9. The electric motor according to claim 1, wherein said annular washer body of said spring washer bears against said outer ring of said at least one rolling bearing with said alternatingly axially flared half-wave trains, flared axially in a same axial direction and being centering-element-free.

10. The electric motor according to claim 1, wherein said spring washer is a wave-shaped spring washer with said radially inward directed centering elements being a stamped/bent part.

11. The electric motor according to claim 4, wherein said washer outer edge is flared axially in a direction in which said shaft opening configured as a passage is flared.

12. The electric motor according to claim 10, wherein said radially inward directed centering elements are made from a strip of spring steel.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0029] FIG. 1 is a diagrammatic, sectional view of an electric motor with a motor housing and with a stator and with a rotor on a motor shaft and with an A-side and B-side bearing plate with a ball bearing inserted therein and with a pretensioned (positioned) wave-shaped spring washer on the B-side ball bearing;

[0030] FIG. 2 is a perspective view of the wave-shaped spring washer with radially inward directed centering elements at each half-wave train;

[0031] FIG. 3 is a side view of the wave-shaped spring washer with the radially inward directed centering elements at each half-wave train;

[0032] FIG. 4 is a sectional view of a detail from FIG. 1 in the region of the B-side ball bearing with a spring washer inserted in a bearing retainer and supported on the motor shaft by means of centering elements;

[0033] FIG. 5 is a plan view in partial section of the spring washer supported on the motor shaft via the centering elements;

[0034] FIG. 6 is a perspective and sectional view according to FIG. 4 of the spring washer pretensioned in the bearing retainer by means of a tension washer; and

[0035] FIG. 7 a plan view according to FIG. 6 of the pretensioned spring washer with the formation of a gap between the centering elements and the motor shaft.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Mutually corresponding parts and sizes are provided with the same reference signs in all the figures.

[0037] Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown essential parts of an electric motor 1, which is preferably an electronically commutated inner rotor motor and is preferably used as a steering motor of a motor vehicle. The electric motor 1 has a stator 2 and a rotor 3 which is arranged fixed to a motor shaft 4. The latter is mounted so that it can move in rotation about an axis of rotation (motor axis) 8 in an A-side ball bearing 5 and in a B-side ball bearing 6 inside a motor housing 7. The axis of rotation 8 is oriented in the axial direction A which, in the same way as the radial direction R related to it, is illustrated in FIG. 1 as an arrow.

[0038] A B-side bearing plate (housing bearing plate) 9 with a bearing retainer 10 for the ball bearing 6 is provided in the cylindrical (hollow cylindrical) motor housing 7. The B-side bearing plate 9 forms a partition between a motor space 7a in which the rotor 3 with the motor shaft 4, held in the ball bearings 5, 6, and the stator 2 are arranged, and a receptacle 7b for electronics (not illustrated) for controlling the electric motor 1.

[0039] The stator 2 has a number of stator teeth 11, arranged in a star shape, which carry coils (stator coils) 12. The coils 12 are associated with their coil ends (winding wire ends) 13 with individual strands or phases and are interconnected by means of a connecting ring 14 in a star or delta connection and lead to phase terminals 15 for supplying current to the rotating-field winding.

[0040] In the case of the three-phase electronically commutated electric motor 1, the stator 2 has three phases and thus at least three phase windings to which electric current is applied in a phase-shifted fashion. They generate a magnetic rotating field within which the rotor 3 provided with permanent magnets rotates about the axis of rotation 8.

[0041] As can be seen in FIGS. 3 and 4, three phase contacts or terminals, only two phase contacts 15 of which can be seen, project via openings (not illustrated in detail) in the bearing plate 9, into the receptacle 7b, provided for the motor electronics, which is surrounded by a cylindrical housing section 7c, projecting axially above the bearing plate 9 there. The phase contacts or terminals 15 are connected to the coils 12 interconnected to form a stator winding (rotating-field winding) and are contacted with the motor electronics.

[0042] An A-side bearing plate 16 with a bearing seat 17 for the ball bearing 5 forms a housing cap with which the motor housing 7 is closed. The ball bearing 5 there is pressed into the bearing seat 17 with its outer ring 5a so that it is fixed to the housing, while the inner ring 5b of the ball bearing 5 is pressed onto the motor shaft 4 so that it is fixed thereto. The bearing seat 17, as a bearing retainer of the A-side bearing plate 16 for the ball bearing 5 there, is configured with a tight or press fit for the outer ring 5a of the ball bearing 5. On the housing side of the A-side bearing plate 16, the electric motor 1 can be coupled, for example, to a steering rod of a vehicle steering mechanism via its motor shaft 4 by means of a gearbox.

[0043] The axially drawn-in bearing retainer 10, having a through opening 18 for the motor shaft 4, of the B-side bearing plate 9 for the ball bearing 6 is configured with a sliding fit. This means that, although the inner ring 6b of the ball bearing 6 is again pressed onto the motor shaft 4 so that it is fixed thereto, the outer ring 6a of this ball bearing 6 just lies (with a loose fit) in the bearing retainer 10. As a result, when the electric motor 1 is mounted, its motor shaft 4 can be inserted into the motor housing 7 with the stator 2 also already accommodated therein, together with the rotor 3 fixed to the shaft and with the ball bearings 5, 6 already assembled so that they are fixed to the shaft. The ball bearing 6 fixed to the shaft is here pushed into the bearing retainer 10 from that bearing side 9a of the bearing plate 9 which faces the motor space (housing interior) 7a. The A-side bearing plate 16 can here be assembled in or on the motor housing 7 as a housing cap together with the motor shaft 4 and with the rotor 3 and with the B-side ball bearing 6.

[0044] The outer ring 6a of the ball bearing 6 is pretensioned by means of a wave-shaped spring washer 19, illustrated separately in FIGS. 2 and 3, which is inserted, on that bearing side 9b of the bearing plate 9 which faces away from the rotor 3 and the motor space 7a, in the bearing retainer 10 inside the receptacle 7b for the motor electronics. The wave-shaped spring washer 19 is preferably a stamped/bent part made from a strip of spring steel.

[0045] The spring washer 19 has a central shaft opening (opening) 19a for the motor shaft 4, and a washer body 19b surrounding (encircling) this opening 19a. The annular washer body 19b of the spring washer 19 has, in the circumferential direction U of the washer, a number of wave trains or wave periods 20 with alternatingly axially flared half-waves or half-wave trains 20a, 20b. In the exemplary embodiment, the spring washer 19 has three wave trains 20 with three half-waves or half-wave trains 20a oriented (flared) in one axial direction A and with three half-waves or half-wave trains 20b oriented (flared) in the opposite axial direction A.

[0046] The spring washer 19 has in the exemplary embodiment three radially inward directed centering elements 21 on the inner circumference, i.e. on the inner opening edge or inner diameter 19c of the annular washer body 19b, i.e. on the opening edge of the opening 19a. They each have as a centering arm a radial web 21a integrally formed with a fixed end on the inner circumference 19c of the annular washer body 19b of the spring washer 19. A centering section 21b in the shape of an arc of a circle is integrally formed on the radial web 21a at that web end which faces away from the inner circumference 19c of the annular washer body 19b. The centering elements 21 are arranged (integrally formed) on half-wave trains (half-waves) 20b, axially flared in the same axial direction A, of the wave-shaped washer body 19b of the spring washer 19.

[0047] As can be seen in FIGS. 4 and 5, the centering sections 21b, in the shape of an arc of a circle, of the centering elements 21 bear against the motor shaft 4 when the spring washer 19 is untensioned. As a result, the spring washer 19 can be assembled in a fault-free fashion, as can be seen in FIG. 4. When it is mounted, the spring washer 19 is thus supported on the motor shaft 4, and centered thereon, via the centering elements 21.

[0048] As can be seen in FIG. 6, the spring washer 19 is pretensionable by means of an annular tension washer 22 inserted in force-fitting fashion in the bearing retainer 10 and is pretensioned or positioned by the tension washer 22 in the course of mounting. The tension washer 22 has a shaft opening 22a, configured as a passage, for the motor shaft 4. The stiffness of the tension washer 22 is already increased by means of the passage in the form of an axial flaring or bending upward of the opening edge 22b of the tension washer 22. In order to further increase the stiffness of the tension washer, its washer outer edge 22c is also flared axially, and to be precise in the same axial direction A as the central passage 22b of the tension washer 22.

[0049] The direction in which the passage 22b and the washer edge 22c of the tension washer 22 are flared (bent upward) is oriented in the direction of the retainer opening 23, arranged in the receptacle 7b of the motor housing 7, of the bearing retainer 10, via which retainer opening 23 the tension washer 22 is inserted into the bearing retainer 10 and pressed in there. The washer body 19b of the wave-shaped spring washer 19 bears against the outer ring 6a of the ball bearing 6 with those of the wave half-trains 22b, flared axially in the same axial direction A, on which no centering elements 21 are provided. The centering elements 21 are thus axially spaced apart from the ball bearing 6 and from its outer ring 6a. This can be seen in FIGS. 4 and 6 and in FIG. 3.

[0050] FIG. 7 illustrates the spring washer 9, placed onto the motor shaft 4, with its centering elements 21 in the tensioned (positioned) state. In the course of the tensioning of the spring washer 19, its half-wave trains (half-waves) 22a, 22b are moved axially in the direction of the ball bearing 6 by means of the tension washer 22. The wave-shaped spring washer 19 and its washer body 19b are thus deformed. Consequently, the centering elements 21 retreat radially inward and thus lose contact with the motor shaft 4 with the formation of a (shaft) gap 24.

[0051] In summary, the invention relates to an electric motor 1 with a motor shaft 4 which is arranged in a motor housing 7, wherein the motor shaft 4 is mounted so that it can move in rotation about an axis of rotation 8 in at least one rolling or ball bearing 6, inserted in a bearing retainer 10, with an outer ring 6a and with an inner ring 6b fixed to the motor shaft 4. The outer ring 6a of the rolling bearing 6 is pretensioned by means of a spring washer 19 which is inserted in the bearing retainer 10 and has a number of wave trains 20 with alternatingly axially flared half-wave trains 20a, 20b. The spring washer 19 has on the inner circumference 19c a number of centering elements 21 which bear against the motor shaft 4 when the spring washer 19 is untensioned and is spaced apart, in the tensioned state of the spring washer 19, from the motor shaft 4, in particular with the formation of a (shaft) gap 24.

[0052] The claimed invention is not limited to the abovedescribed exemplary embodiments. Rather, other variants of the invention can also be derived therefrom by a person skilled in the art within the scope of the disclosed claims without going beyond the subject-matter of the claimed invention. In particular, all the individual features described in connection with the various exemplary embodiments can moreover be combined in a different fashion within the scope of the disclosed claims without going beyond the subject-matter of the claimed invention.

[0053] In addition, the described solution can be used not only in the specific illustrated use case but also in a similar design for other motor vehicle applications such as, for example, door and tailgate systems, window lifters, vehicle locks, adjustable seat and interior systems as well as for other electrical drives, for example a brake booster, in the vehicle.

[0054] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention.

LIST OF REFERENCE SIGNS:

[0055] 1 electric motor [0056] 2 stator [0057] 3 rotor [0058] 4 motor shaft [0059] 5 (A-side) ball bearing [0060] 5a outer ring [0061] 5b inner ring [0062] 6 (B-side) ball bearing [0063] 6a outer ring [0064] 6b inner ring [0065] 7 motor housing [0066] 7a motor space [0067] 7b (electronics) receptacle [0068] 7c housing section [0069] 8 axis of rotation [0070] 9 (B-side) bearing plate [0071] 9a, 9b bearing side [0072] 10 bearing retainer [0073] 11 stator tooth [0074] 12 coil [0075] 13 coil end [0076] 14 connecting ring [0077] 15 phase terminal/contact [0078] 16 (A-side) bearing plate [0079] 17 bearing seat [0080] 18 through opening [0081] 19 spring washer [0082] 19a shaft opening/opening [0083] 19b washer body [0084] 19c inner circumference/opening edge [0085] 20 wave train/period [0086] 20a half-wave/half-wave train [0087] 20b half-wave/half-wave train [0088] 21 centering element [0089] 21a radial web/centering arm [0090] 21b centering section [0091] 22 tension washer [0092] 22a shaft opening [0093] 22b opening edge/passage [0094] 22c washer outer edge [0095] 23 shaft gap/gap [0096] A axial direction [0097] R radial direction [0098] U circumferential direction