Abstract:
An electric motor for actuators in a motor vehicle has an armature shaft, which is supported in a pole housing that includes a jacket and a bearing cover on at least on one end face for accommodating a bearing for the armature shaft, and at least one radial recess is formed in the pole housing, which, once the pole housing has been fully assembled, is suitable for engagement by at least one radial fastening segment of a transmission interface in the pole housing, in order to attach the electric motor to the transmission interface.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The invention described and claimed hereinbelow is also described in German Patent Application DE 10 2005 030 217.3 filed on Jun 29, 2005. This German Patent Application provides the basis for a claim of priority of invention under 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The present invention relates to an electric motor and a transmission drive unit for use in adjustment devices in a motor vehicle. 
     Publication DE 100 19 512 A1 makes known a power window drive, the housing of which includes a pole pot and a housing that closes the pole pot. The housing that closes the pole pot is a transmission housing with an integrated electronics housing. A separate component—as a brush holder—is located between the two housing parts, and also serves as a seal between the two housing parts. The pole pot is composed of a deep-drawn, flattened cylindrical tube, on the open end of which a flange is integrally formed, in which holes are formed for receiving screws. Blind threads are formed in the flange of the transmission housing, into which the screws are turned, thereby fixedly connecting the two housing parts with each other. More recesses are formed in the flange of the pole pot than are required for the connection with a transmission housing. A pole pot of this type is therefore suited for connection with different transmission housings with various counter-recesses, although the electric motor must always be installed and secured axially in the transmission housing. For this reason, the open electric motor that is used is not suited for use without a transmission housing. 
     SUMMARY OF THE INVENTION 
     The inventive electric motor and the inventive transmission drive unit have the advantage that, due to the formation of the radial recess in the pole housing, it is possible to manufacture a very simple, installable connection of an electric motor with a customer-specific transmission interface in a very cost-favorable manner. The pole housing may always be manufactured in a uniform manner, and it may be combined, in a modular system, with different transmission housings, transmission interfaces, adapter elements, or fastening flanges. The radial recesses may be fabricated in a uniform manner world-wide using simple standard processes without the need to use additional material. When the electric motor is installed radially in a two-shelled transmission housing, the electric motor is fixed in position securely with the transmission housing by the fact that fastening segments integrally formed on the transmission interface engage in the radial recesses. The bearing cover reliably closes the pole housing, so that the electric motor may be used universally, even without being combined with a transmission housing. By designing the transmission housing as housing parts that are connectable with each other radially, injection-molding tools without plungers may be advantageously used for manufacturing, thereby considerably reducing the tool costs. The radial recess forms a compact, stiffly-connected interface between the electric motor and any housing parts, and is therefore particularly well-suited for use as a universal connection for a basic motor. A system of this type also makes it easier to disassemble a drive unit of this type for purposes of repair or recycling. 
     Depending on the method used to manufacture the pole housing, the radial recess may be formed in one end of the jacket of the pole housing, or in the bearing cover thereof. When separate punched parts are used, e.g., for the bearing cover and the jacket, the radial recesses may be punched out—very favorably—before the pole housing is assembled. 
     When the pole housing is manufactured using a deep-drawing process, the bearing cover may be integrally formed very easily as a single piece on the end face of the jacket. As a result, a pole pot that is closed on one side may be manufactured in one working step, with an opening being left for the armature shaft that extends out of the pole pot. By forming the bearing cover as a single piece with the jacket of the pole housing, the calotte bearing and, therefore, the armature shaft may be located very exactly in the center inside the pole pot, thereby reducing the assembly tolerances between the armature and the permanent magnet. 
     By installing both bearing covers on the pole housing, the electric motor may also be used without a transmission, as a standalone assembly. Via the opening in the bearing cover, an effective interface for the power transfer is provided. The armature shaft extends through the opening and out of the pole housing, to drive an adjusting device using a driven element. As an alternative, a drive shaft of the adjusting device engages—through the opening—with the armature shaft in a form-fit manner in order to couple force. The armature shaft does not extend out of the pole housing. 
     It is particularly favorable to design the radial recess as an opening in the pole housing wall, since this allows material to be cut out. This weight of the electric motor is reduced as a result. The opening may punched out during the deep-drawing process of the pole pot, which is very cost-favorable and easy to handle in terms of process engineering. 
     As an alternative, a radial recess of this type may be created using plastic cold reforming by easily impressing a certain wall section using a stamping tool. Advantageously, no waste is produced in this process, material is not cut out, and is only deformed. The dimensional stability of the radial recesses is increased as a result. 
     When the outer diameter is smaller in the region of the radial recess than the outer diameter of the rest of the essentially cylindrical pole housing, the diameter of the corresponding fastening segments of the transmission interface may also be made smaller, so that the outer diameter of the transmission housing does not extend beyond the diameter of the pole housing at the connection point. In this manner, the installation space of the transmission housing may be reduced in the connection region. 
     To secure the electric motor against turning in the transmission housing or in the fastening flange, regions of the pole housing are left non-deformed between the radial recess, so that they may form a stop for the fastening segments in the circumferential direction. No additional fabrication outlay is required to achieve this. 
     When the radial recesses are formed on the pole pot in diametrically opposed positions, so that radial, diametrically opposed segments engage therein, the electric motor is fixedly secured at the transmission interface evenly around the entire circumference. 
     To create a magnetic return between the permanent magnets, a second pole tube may be located around the pole housing jacket, which completely encloses the pole housing jacket. 
     To unambiguously fix the electric motor in position relative to the transmission housing and the fastening flange, a centering neck is integrally formed with the bearing cover, which centers the electric motor radially when it engages in a corresponding counter-recess. The region of the bearing cover, which accommodates, e.g., a calotte bearing, a roller bearing, or a bearing retaining spring in the interior, may be designed cylindrical in shape in the axial direction, to enable centering to take place concentrically with the armature shaft. 
     In a further embodiment of the electric motor, axial recesses are integrally formed in the pole housing in addition to the radial recesses, into which the fastening segments of the transmission interface may be inserted axially, to attach the electric motor. The axial recesses are formed as single pieces with the radial recesses in the pole housing, so that they form, e.g., an L-shaped recess for a bayonet connection. In the case of a customer&#39;s fully-assembled transmission housing, this makes it possible to easily install the electric motor axially without opening the transmission housing or without the need to use additional connection means, such as screws or rivets. 
     Advantageously, the entire transmission drive unit may be installed radially by inserting the electric motor radially into a portion of the transmission housing. At least one fastening segment of the transmission housing engages in the at least one radial recess in the pole housing. By closing the transmission housing with a radially installable cover or a half shell, the electric motor is permanently secured against moving relative to the transmission housing, while the transmission housing is closed at the same time. 
     By using a transmission housing made of half shells, all components of the drive unit, including the electric motor, may be installed in the same radial direction, thereby enabling the assembly line to be markedly simpler in design. 
     It is particularly favorable when at least two and preferably four fastening segments are integrally formed with the transmission housing (main body and cover), since this may prevent the electric motor from tipping in all four directions—which are perpendicular to each other—transversely to the armature shaft. 
     If the fastening segments on the transmission interface are formed via axial holders as bayonet elements that engage in the corresponding, axial and radial—and L-shaped, in particular—recesses of the pole housing, the electric motor may be very easily attached to a customer&#39;s fully-assembled transmission housing. 
     If an electric motor having the exact same design is to be attached at various transmission interfaces, the adapter element includes fastening segments, which are designed, e.g., as clip elements or bayonet segments that engage in the radial recesses of the pole housing. As a result, a universal basic motor may be secured in a transmission housing and in any fastening flange without the need to change the design of the electric motor. The adapter element therefore practically forms the interface between the electric motor and any type of adjustment mechanism (transmission interface). 
     The inventive assembly method enables a standard motor to be attached to a customer-specific transmission in an extremely simple manner while using an extremely small amount of installation space. The motor may be slid on axially and then rotated relative to the transmission, in order to fix the motor in position axially. In addition, a locking device may be used to secure the bayonet connection against the motor coming loose during operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the inventive device are presented in the drawing and are described in greater detail in the description below. 
         FIG. 1  shows a transmission drive unit, in a cross section, 
         FIG. 2  shows a cross section through a further exemplary embodiment, with a bayonet connection, 
         FIGS. 3 and 4  show views of two further inventive electric motors, 
         FIG. 5  shows a cross section through a further exemplary embodiment, with an adapter element, and 
         FIG. 6  shows a transmission interface formed as a fastening flange. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A transmission drive unit  12  is shown in  FIG. 1 , with which a separate electric motor  10  is connected with a partially-shown transmission interface  15  that is designed as transmission housing  16 . Electric motor  10  includes a pole housing  18  with a pole housing jacket  20  and bearing covers  26 ,  28  integrally formed with its end faces  22 ,  24 . Bearing covers  26 ,  28  accommodate bearings  30 —which are designed as sliding bearings and, in particular, as calotte bearings in the exemplary embodiment—in which an armature  33  is supported via an armature shaft  32 . An armature stack  34  with electrical windings  36  is located on armature shaft  32 . Electrical windings  36  interact with permanent magnets  38  located on pole housing jacket  20 . Armature shaft  32  passes through bearing cover  26  on end face  22  via a hole  40  located therein in the axial direction. Armature shaft  32  extends—with a not-shown driven element—into transmission element  16 , in order to provide a drive torque for movable parts in a motor vehicle using a not-shown transmission, e.g., a worm gear. In the exemplary embodiment, pole housing  18  is manufactured by deep-drawing a metal sheet. Jacket  20  is formed as one piece with bearing cover  26 . Armature  33  is installed in pole housing  18  and is slid with armature shaft  32  through opening  40 , then separate bearing cover  28  is installed. For certain applications, a second pole housing wall  21 —as flux return ring  21 —is also located on jacket  20 . A radial recess  42  is located in the region of bearing cover  26 , which, in the right half of the illustration, is formed as a punched-out opening  43  in pole housing wall  49 . In the left half of the illustration, radial recess  42  is impressed into housing wall  49  via plastic material deformation  41 . No material waste is produced in the manufacturing process. Radial recesses  42  are located in a region  57  of pole housing  18 , outer diameter  44  of which is ideally smaller than outer diameter  48  of pole housing jacket  20 . Region  45  of bearing cover  26  is designed as centering neck  50 , which, in the installed state, engages in a corresponding counter-recess  52  of transmission housing  16 . To attach electric motor  10  to transmission housing  16 , fastening segments  53  of transmission housing  16  engage in radial recesses  42  of pole housing  18 . Fastening segments  53  bear axially against the boundary of radial recess  42 . Electric motor  10  is therefore fixed in position axially in transmission housing  16 . Electric motor  10  is inserted, e.g., radially, in a first half shell  62  of transmission housing  16 , so that at least one fastening segment  53  engages in at least one radial recess  42 . After electric motor  10  is inserted into first half shell  62  and the not-shown transmission is installed, a second half shell  63  is installed radially to armature shaft  32  onto first half shell  62 , and they are connected with each other using connecting elements  66 , which engage in recesses of the two transmission housing parts  62 ,  63 . In  FIG. 1 , at least one further fastening segment  53  of second half shell  63  engages in at least one further radial recess  42  of pole housing  18 . Fastening segments  53  or radial recesses  42  do not include receptacles for connecting elements between electric motor  10  and transmission housing  16 . Electric motor  10  is therefore securely connected with a housing main body  63  solely via the connection of transmission housing parts  62  and  63 , and/or a cover  62 . 
     The electric motor shown in  FIG. 2  includes a type of bayonet connection as the mechanical interface for connection with transmission housing  16  or transmission interface  15 . To this end, an axial recess  47  is formed in radial recess  42 , in which fastening segment  53 —which is connected to transmission interface  15  via an axial holder  55 —is capable of being guided axially into the pole housing. During installation, electric motor  10  is slid axially into corresponding interface  15 , and then, in the manner of a bayonet connection, it is rotated by a certain angle and, optionally, snapped into position. With this type of connection, housing  16  need not include at least two radially connectable half shells. Instead, it may be designed as a bayonet connection. Radial recess  42  is impressed directly into jacket  20  via plastic deformation, although it may be formed via material removal, e.g., punching out. Radial recesses  42  are formed on the end of pole housing  18  on which bearing cover  26  is formed as one piece. As an alternative, radial recesses  42  may be integrally formed with the other end, which is closable using a separate bearing cover  28  to assemble electric motor  10 . To this end, jacket  20  includes flexible fastening tabs  94 , which are formed around projections of bearing cover  28 . Armature shaft  32  extends substantially along the length of pole housing  18 , so that, for force coupling, a coupling element  96  (e.g., a flex shaft  96 ) extends through opening  40  in bearing cover  26  into an inner polyhedron  98  (e.g., a rectangle  98 ) of armature shaft  32 . As an option, a torque pick-off of this type may be provided on one or both sides  22 ,  24  of pole housing  18 . Thrust washers  100 —which are preferably made of plastic—are located between bearings  30  and armature  33 . Armature shaft  32  bears axially against bearings  30  via thrust washers  100 . Thrust washers  100  are non-rotatably connected with armature shaft  32  and/or with armature components  102  located thereon, such as receiving sleeve  102  for an annular magnet  104 . 
       FIG. 3  shows a section of a further electric motor  10 , with which radial recesses  42  are impressed into the wall of pole housing  18  via plastic cold deformation  41 . The material of pole housing  49  is merely impressed inward, and is not cut out, so an opening in wall  49  is not created. In one variant, wall  49  is deformed to such an extent that an opening (slot  51 ) forms in the pole housing. Pressed-in wall region  59  is designed as a flat surface, against which fastening segments  53  bear after installation in transmission interface  15 . As an alternative, wall region  59  is arched inward into pole housing  18 . In the embodiment shown in  FIG. 3 , no axial recesses  47  are formed in pole pot  18 , since electric motor  10  is designed to be installed radially into a transmission housing  16  with a cover, and/or with two half shells  62 ,  63 . 
       FIG. 4  shows a further exemplary embodiment, with which radial recesses  42  are designed as openings  43  in pole housing wall  49 . They are formed, e.g., by punching a deep-drawn metal sheet of pole housing  18 . In addition to radial recesses  42 , axial recesses  48  are also formed in axial direction  109 , which—together with radial recesses  43 —form a common opening  43 , which is, e.g., L-shaped. In a not-shown variant of the embodiment, axial recesses  47  are formed via plastic deformation, so that they are impressed into housing wall  49  together with radial recesses  42 . Axial recesses  47  are suited for axial installation  109  of electric motor  10  in transmission interface  15 , in particular for a bayonet connection  17 . Fastening segments  53  are inserted axially into axial recesses  47 , then electric motor  10  is rotated in circumferential direction  108 . Fastening segments  53  are pushed into radial recesses  42  in circumferential direction  108  and fix electric motor  10  into position, at least in the axial direction. A locking device may be also be provided, which prevents electric motor  10  from accidentally rotating in reverse in circumferential direction  108  when in the installed state. 
     A further exemplary embodiment of a transmission drive unit  12  is shown in  FIG. 5 , with which electric motor  10  is not connected directly in transmission housing  16 , but is connected with an adapter element  13 . Adapter element  13  also includes fastening segments  53 , which engage in radial recesses  42  of pole housing  18 . Fastening segments  53  are designed, e.g., as snap-in connection  11 . When adapter element  13  is slid onto pole housing  18  in axial direction  109 , fastening segments  53  slide over housing  18  until they snap into radial recesses  42  in a form-fit manner and fixedly connect adapter element with pole housing  18 . Adapter element  13  is braced axially via a seat  23  against a collar  25  of the pole housing, and is braced with fastening segment  53  in radial recess  42 . Radial recesses  42  also form a stop  19  for fastening segments  53  in circumferential direction  108 , so that adapter element  13  is also secured against rotation. Adapter element  13  includes radial projections  27  around its outer circumference, with which adapter element  13  is connectable with a transmission interface  15 , in particular via radial recesses formed therein. Using adapter element  13 , the position of radial recesses  42  in pole housing  18  and fastening segments  53  on transmission interface  15  may be interchanged. 
       FIG. 6  shows a transmission interface  15 , which is designed as fastening flange  80 , which is connectable with a transmission drive unit  12  and/or an electric motor  10 , according to the present invention. Fastening flange  80  includes receptacles  86  for connecting means for attachment to a body part  15 . Fastening flange  80  is designed as one-piece bent blank  81  and includes radial fastening segments  53 , which are connected with fastening flange  80  via axial holders  55 . A hole  82  is located inside fastening segments  53  in the center, in which output shaft  32 ,  96  and/or centering neck  50  of transmission drive unit  12  may engage. Fastening flange  80  is slid on axially in the manner of a bayonet, and radial fastening segments  53  of fastening flange  80  engage in axial recesses  47  of pole housing  18 . Fastening flange  80  is then rotated in circumferential direction  108  relative to pole housing  18 , so that radial fastening segments  53  are pushed into radial recesses  42 , which are formed in pole housing  18  as wall openings  43  or via plastic deformation  41 . 
     It should be noted that, with regard for the exemplary embodiments presented in the figures and the description, many different combinations of the individual features are possible. For example, the specific embodiment of radial recess  42 , and its position in pole housing  18  may be varied depending on the method used to manufacture it. In addition, fastening segments  53  may have any shape, for combination with a transmission housing  16  or an adapter element  13 . The design of armature  33 , transmission housing  16 , and the transmission may reflect any known application. The special feature of the present invention lies in the fact that an identical electric motor  10  is used as basic motor  10  for a modular principle for combination with various transmission interfaces  15 , such as transmission housing  16 , fastening flange  80 , or adapter  13 , without the need for separate connecting means for connection with adjacent transmission interface  15 . Inventive electric motor  10  and/or transmission drive unit  12  are/is preferably used for seat adjusting devices in a motor vehicle, although they/it may also be used for any other type of actuator.