Electric machine

• US 4,501,983 A
• Filed: 03/31/1981
• Issued: 02/26/1985
• Est. Priority Date: 01/30/1978
• Status: Expired due to Fees

• Current Assignee: Papst Licensing GmbH & Company Kg
• Original Assignee: Papst-Motoren GmbH & Company KG (Ebm-Papst Mulfingen GmbH & Company KG)
• Inventors: Schmider, Fritz
• Primary Examiner(s): SKUDY, ROBERT
• Application Number:
  US06/249,339
• Time in Patent Office: 1,428 Days
• Field of Search: 310/229, 310/112-114, 310/157-171, 310/154, 310/68 R, 310/268, 310/89, 310/72, 310/127, 310/128, 310/239, 310/51, 310/219, 310/232, 310/242, 310/248, 310/249 , 310/75 R, 307/105
• US Class Current: 310/113
• CPC Class Codes: H01R 39/36 Connections of cable or wire to brush
• CPC Class Codes: H01R 39/39 wherein the brush is fixedly mounted in the holder
• CPC Class Codes: H01R 39/40 enabling brush movement within holder during current collection
• CPC Class Codes: H02K 11/012 Shields associated with rotating parts, e.g. rotor cores or rotary shafts
• CPC Class Codes: H02K 11/028 Suppressors associated with the rotor
• CPC Class Codes: H02K 5/148 Slidably supported brushes
• CPC Class Codes: H02K 5/24 specially adapted for suppression or reduction of noise or vibrations
• CPC Class Codes: H02K 7/20 Structural association with auxiliary dynamo-electric machines, e.g. with electric starter motors or exciters

Abstract

The motor housing comprises a cup-shaped ferromagnetic part having an open end and an axial end plate of ferromagnetic material closing off the open end to form a motor housing of rectangular cross-section when viewed in longitudinal section. A generally disk-shaped rpm-signal generating structure is mounted interiorly of the motor housing, coaxial with the rotor axis, at one axial end of the housing, and just inward of a wall of the motor housing which forms part of the flux-conducting magnet system of the motor, whereby such wall shields the rpm-signal generating structure at least against electromagnetic interference originating exteriorly of the motor housing. The motor comprises slip rings or commutator segments on whose surfaces stationary brushes ride. The brushes are provided with longitudinal recesses, projections or internal bores, so that the brush configuration itself makes for longitudinal brush guidance, and the brushes are mounted on brush guide members which engage such longitudinal portions of the brush. The rotor shaft and the motor housing are conductively connected by means of a contact element engaging the rotor shaft at one axial end, to prevent build-up of electrostatic fields as between the rotor shaft and the motor housing.

Claims

1. An electric drive motor for signal processing equipment comprising a stator and a rotor together forming a cylindrical radial air gap, a stationary motor housing of generally cylindrical configuration, said motor housing being made of soft magnetic material and serving as part of the magnetic circuit of the motor, brush means located between one axial end of said motor housing and said rotor;

a separate flux guide member of generally cylindrical configuration mounted in the interior of the motor housing between the other axial end thereof and said rotor coaxial with the rotation axis of the latter, and having a diameter slightly smaller than the diameter of the motor housing and being of a magnetically soft material;

rpm-signal generating means located in the flux guide member part to be shielded at least from electromagnetic interference originating exteriorly of the motor housing;

the rpm-signal generating means including a relatively thin ferromagnetic rotor disk connected to the rotor coaxially with the axis of rotation thereof and having a plurality of teeth on its circumference, a stationary ring surrounding said rotor disk and being formed with a number of permanent magnetic pole pairs of opposite pole polarity and corresponding to the number of teeth on the rotor disk, and a stationary inductive coil arranged coaxially with the axis of rotation of said rotor in proximity to the path of movement of the teeth of the rotor disk to generate rpm signals.

2. An electric drive motor as claimed in claim 1 further comprising a soft-iron ring connected to the rotor disk coaxially with the axis of rotation thereof, and said inductive coil surrounding said soft-iron ring.

3. An electric drive motor as defined in claim 2 wherein said ferromagnetic rotor disk is connected to the rotor by means of a carrier disk of a magnetically non-conductive material.

4. An electric drive motor as defined in claim 3, wherein said flux guide member part has a cup-shaped configuration defining a magnetic flux-conducting cylindrical wall enclosing said inductive coil and a bottom wall formed with a central opening for accommodating the rotary soft-iron ring connected to the rotor disk.

5. An electric drive motor as defined in claim 1 wherein said rotor comprises a stack of rotor plates, the stack of rotor plates including recesses, the motor furthermore comprising anti-interference circuit components accommodated within the recesses in the stack of rotor plates.

6. An electric drive motor as defined in claim 1 wherein the flux guide member part has a cup-shaped configuration of deep-drawn soft-iron material, an inner wall portion of the motor housing being formed with a peripheral recess for accommodating said flux guide member part.

7. An electric drive motor as defined in claim 6 wherein said stator includes permanent magnets secured to the inner wall of said motor housing in proximity to said recess portion.

8. An electric drive motor as defined in claim 7 further comprising electrically insulating spacers for supporting said cup-shaped flux guide member part.

9. An electric drive motor as defined in claim 8 wherein said motor is constituted by a deep-drawn cup-shaped part of soft magnetic material having a base and an open end, and an axial end plate closing off the open end of the cup-shaped part and likewise made of soft magnetic material.

10. An electric drive motor as defined in claim 1 wherein said rotor comprising around rotor and further a cylindrical collector arranged for joint rotation with said rotor;

said brush means including elongated stationary brushes riding upon the surface of the collector;

means mounting the brushes for sliding movement in the direction of elongation of the brushes, a vibration-damping brush carrier mounted in the interior of the motor housing, and each of the brushes being configured to have two longitudinally extending lateral grooves of rectangular cross-section located at opposite sides of each of the brushes, the means mounting each of the brushes comprising a stamped, sheet-metal component mounted on the brush carrier and defining two guide portions engaging in respective ones of the lateral grooves for guiding of each of the brushes for movement in the direction of elongation each of the brushes.

11. An electric drive motor as defined in claim 1, wherein said motor housing is of electrically conductive material, said rotor being arranged for rotation within the motor housing and including a rotor shaft an end portion of which extends exteriorly of the motor housing, a support structure of electrically conductive material mounted on the motor housing and supporting said exterior end portion of the rotor shaft, and an electrically conductive contact element springily pressing against the face of the exterior end portion of the rotor shaft and conductively connected to the motor housing serving to present the build-up of electrostatic fields between the rotor shaft and motor housing.

12. An electric drive motor as defined in claim 11, the end portion of the rotor shaft which is supported on the exterior end portion of the rotor shaft which is supported on the support structure having a convex end face, the electrically conductive contact element pressing against the convex end face.

13. An electric drive motor as defined in claim 12, the contact element pressing against the convex end face of the rotor shaft at a location near the rotation axis of the rotor shaft.

14. An electric drive motor as defined in claim 1, wherein said rotor a wound rotor and further comprising a cylindrical collector arranged for joint rotation with said rotor;

said brush means including elongated stationary brushes riding upon the surface of the collector;

means mounting the brushes for sliding movement in the direction of elongation of the brushes, each of the brushes having a configuration which includes a longitudinal guidance portion cooperating with the mounting means for establishing the longitudinal guidance path of each of the brushes, said longitudinal guidance portion of each of the brushes comprising a recess extending longitudinally in at least one lateral side of each of the brushes, and the means mounting the brushes for sliding movement comprising a printed circuit carrier board configured to engage the longitudinal guidance portion of each of the brushes.

15. An electric drive motor as defined in claim 14, each of the brushes being configured to have two longitudinally extending lateral grooves of rectangular cross-section located at opposite sides of each of the brushes, the printed circuit carrier board comprising two edge portions for guiding each of the brushes for movement in the direction of elongation thereof.

16. An electric drive motor as defined in claim 14, the printed circuit board being a synthetic plastic molded member made of vibration-damping polyamide material.

17. An electric drive motor as defined in claim 14, the electrical current flowing through the brushes flowing through the longitudinal guidance portion of the brush and the means mounting the brushes being made of electrically conductive material.

18. An electric drive motor as defined in claim 14, the means mounting the brushes for sliding movement including a spring holder extending in the direction of elongation of each of the brushes and a biasing spring held on the spring holder and urging the brush in the direction towards the collector.

19. An electric drive motor as defined in claim 14, the means mounting the brushes for sliding movement including a spring holding structure and a biasing spring held on the spring holding structure for urging the brushes in the direction towards the collector and a brush holder mounted on the spring holding structure.

20. An electric drive motor as defined in claim 1, wherein said rotor is a wound rotor and further comprising a cylindrical collector arranged for joint rotation with said rotor;

said brush means including elongated stationary brushes riding upon the surface of the collector;

means mounting the brushes for sliding movement in the direction of elongation of the brushes, each of the brushes having a configuration which includes a longitudinal guidance portion cooperating with the mounting means for establishing the longitudinal guidance path of each the brushes, said longitudinal guidance portion of the brushes comprising a projection extending longitudinally on at least one lateral side of each of the brushes, and the means mounting the brushes including a recessed guide portion engaging the projection on each the brushes.

21. An electric drive motor as defined in claim 20, the means mounting each of the brushes comprising a guide member made of metal and having a connecting lug, further including a contact strip and connecting cables conductively connected to the connecting lug and to each of the brushes.