Electric motor

Abstract

The invention relates to an electric motor (1) comprising: a multi-part housing (2) which has a housing shell (3) in which a stator-rotor assembly (5) is located; and a housing cover (4) in which an electronics module (10) is accommodated, wherein the housing shell (3) has a circular recess (11) adapted to the shape of the stator-rotor assembly (5) and a tab (12) that adjoins a portion of the edge of the recess (11) and defines a rectangle, wherein the width of the tab (12) is at least equal to the radius of the recess (11), and wherein the housing cover (4) spans both the region of the recess (11) and said tab (12) and has a V-shaped plateau-like elevation (15). This elevation (15) extends from the edge of the recess (11) facing away from the tab (12) into the region of the tab (12) and accommodates a V-shaped printed circuit board (17) which forms part of the electronics module (10) and which widens from the recess (11) towards the tab (12) in accordance with the shape of the V-shaped elevation (15).

Description

[0001] electric motor

[0002] The invention relates to an electric motor which comprises an electronic module and can be used in particular in an electromechanical camshaft adjuster.

[0003] An electric motor with an electronics module is described, for example, in WO 2019 / 206374 A1. This motor is suitable for use in an electric camshaft adjuster or in a mechanism for adjusting the piston stroke of an internal combustion engine. The electronics module of the known electric motor comprises power electronics, driver electronics, and control electronics.

[0004] Another electric motor for a motor vehicle actuator is described in DE 10 2020 131 327 A1. In this case, a plug module is screwed to a housing of the electric motor. The plug module has a groove into which a seal is inserted.

[0005] An electric motor described in US 2021 / 0288561 A1 is also used to adjust the timing of an internal combustion engine. The electric motor includes electronic components. One of the electric motor's sensors is designed as a Hall sensor.

[0006] The invention is based on the object of further developing an electric motor suitable for use in an electromechanical camshaft adjuster compared to the cited prior art, in particular with regard to assembly technology, while at the same time aiming for a compact design and ensuring suitability for various types of internal combustion engines.

[0007] This object is achieved according to the invention by an electric motor having the features of claim 1. The electric motor has a multi-part housing which comprises a housing shell in which a stator-rotor assembly is located, and a housing cover in which an electronic module is accommodated.

[0008] The housing shell forms a circular recess that is matched to the shape of the stator-rotor assembly. A tab that describes a rectangle adjoins a section of the edge of the recess, wherein the width of the tab corresponds at least to the radius, in particular at least to the diameter, of the recess. The housing cover covers both the area of ​​the recess and the aforementioned tab and has a V-shaped, plateau-like elevation that extends from the edge of the recess facing away from the tab into the area of ​​the at least approximately rectangular tab. The V-shaped elevation accommodates a circuit board that is also V-shaped and belongs to the electronics module. The circuit board widens from the recess to the tab in accordance with the shape of the V-shaped elevation.For both the V-shaped elevation of the housing cover and the V-shaped circuit board, sections of the outer contour of the corresponding component can be cut off or rounded, for example, in order to modify the V-shape.

[0009] It has been shown that the V-shaped contour, defined by the housing cover, in particular, provides sufficient space within the housing for accommodating electrical and electronic components while maintaining compact external dimensions, thus creating good conditions for installing the electric motor in different vehicle types. The V-shape of the housing also offers good conditions for installing the electric motor at different angles in different vehicles, if necessary. The electric motor can be designed to be particularly flat on the sides next to the V-shaped protrusion. This translates into a partial reduction in axial installation space.

[0010] The housing shell of the electric motor, for example, is made of sheet steel, whereas the housing cover is made of light metal. In particular, the housing cover of the electric motor can be a light metal sheet part.

[0011] In an advantageous assembly-technically advantageous embodiment, positive-locking connections can be provided between the housing shell and the housing cover. Such connections can be formed by material forming, in particular caulking. For example, positive-locking connections can be produced by clinching. The clinching connection technology is also known under the trademark Tox. In this context, reference is made to the documents DE 10 2021 120 409 A1 and DE 10 2016 115 595 A1 as examples. Clinching connections or other positive-locking connections produced by material forming can also be formed between the housing cover and the printed circuit board. In particular, positive-locking connections can exist both between the housing cover and the housing shell and between the housing cover and the printed circuit board. Components of the electric motor can also be connected to one another by adhesive bonding.

[0012] Pre-assembled motor contacts may be located on the circuit board. Such contacts can be connected to the circuit board via press-fit and can also be designed as insulation displacement contacts. Press-fit connections are connections created by pressing a contact terminal into a circuit board. For technical background information, please refer to documents DE 10 2005 043 033 B3 and DE 10 2008 001 787 A1.

[0013] With the help of the combined press-fit insulation displacement contacts, an electrically conductive connection to the windings of the stator assembly can be established in a simple and reliable manner during assembly of the electric motor. Furthermore, the surface area provided by the circuit board can be divided into a sub-area for logic components and a sub-area for additional functions. The latter sub-area, for example, offers space for components for supplying electrical power and / or for mains filtering. Interfaces, for example, for pulse width modulation and for connecting to a data network, particularly CAN, as well as diagnostic, control, and regulation functions, can be implemented by the electronics module.

[0014] The circuit board can, in particular, be a single-sided circuit board, with the first partial area, i.e. the partial area on which the logic components are located, being defined in particular by the narrower section of the circuit board extending to the tip of the V. The adjoining second, wider partial area of ​​the circuit board, in contrast, can be populated with comparatively tall components, for example electrolytic capacitors, thus enabling an overall particularly space-saving design of the electric motor in the axial direction. In general, this means that components located on the circuit board that are arranged in the area covering the stator-rotor assembly can be flatter than components that are located in an area of ​​the circuit board that covers the tab of the housing shell.

[0015] The flatter components can be assigned to a logic module of the electric motor, whereas the comparatively tall components belong to a power module. From the point of view of electromagnetic compatibility, it is particularly advantageous if the signal lines on the one hand and the power lines on the other, to which the components of the logic module are connected in the first case and the components of the power module in the second case, do not overlap.

[0016] A plug module of the electric motor can be held, in particular, on the housing cover, whereby the contours of the plug module can engage positively with the contours of the housing cover. When the plug module is inserted into the housing cover, electrically conductive connections can be established between the contact surfaces on the plug module and the contact surfaces on the housing cover or on the circuit board.

[0017] Electrical connections through adjacent contact surfaces can complement the previously mentioned design features of the circuit board. In particular, this involves the division into a power section, including the motor contact, which can be implemented using insulation displacement connectors, and a logic section. The second, wider section is used for the power section, while the logic section is located further away from the connector module. The various current paths—namely, power paths on the one hand and signal paths on the other—can thus be implemented not only without crossings but also with short overall lengths.

[0018] The circuit board can be slightly spaced from the inner wall of the housing cover formed by the V-shaped elevation. A potting material containing solids, particularly in the form of solid or hollow spheres, such as glass beads, is introduced into the gap between the circuit board and the wall of the housing cover. The potting compound, which contains fillers, ensures a defined insulation distance between the electronic module and the housing cover. The potting compound also has a defined thermal resistance.

[0019] Such a material, which is processed as a paste or adhesive, i.e., potting material, contributes to reliable heat dissipation within the finished electric motor during intended operation. A mounting counterpart provided by the combustion engine can be used as a heat sink. In general, heat can flow from the electronic module, in particular its power section, to the combustion engine. A heat path can exist that extends from the power section of the electronic module through the potting material and the light metal housing cover of the electric motor to a cylinder head of the combustion engine. The heat path can include screw bosses located near the power section, at which a mechanical and thermally conductive connection is established between the electric motor and the cylinder head.

[0020] The electric motor can optionally be equipped with sensors. In particular, these include sensors for detecting the angular position and / or speed of the electric motor shaft. Such sensors include, for example, a sensor ring located on the rotor of the electric motor. Hard ferrites are possible materials for the sensor ring. In general, any known sensor technology, including magnetic and optical sensors, can be used.

[0021] When it comes to assembling the electric motor and the associated actuator, the fact that the individual, partially pre-assembled components can be attached to an internal combustion engine in an axial direction is particularly advantageous. The axial direction refers to the alignment of the electric motor's motor shaft, which coincides with the longitudinal direction of the camshaft to be adjusted. This applies regardless of the type of actuator connected between the electric motor and the camshaft of the internal combustion engine.

[0022] The applicability of the electric motor is not limited to electromechanical camshaft adjusters. Rather, the electric motor can also be used to drive other components in an automobile, such as a water pump, or for stationary applications.

[0023] An embodiment of the invention is explained in more detail below with reference to a drawing. In the drawings:

[0024] Fig. 1 an electric motor for a camshaft adjuster in perspective view, Fig. 2 components of the electric motor in a sectional perspective view,

[0025] Fig. 3 the electric motor including an electronic module in exploded view,

[0026] Fig. 4 the electric motor including the electronic module in a partially sectioned view,

[0027] Fig. 5 the electronic module including housing cover and plug module of the electric motor,

[0028] Fig. 6 an insulation displacement contact assigned to the electronic module and intended for press-fit mounting,

[0029] Fig. 7 a detail of the electric motor including a positive connection between components of the electric motor,

[0030] Fig. 8 the electric motor in another perspective view.

[0031] An electric motor, designated overall by reference numeral 1, is intended for use in an electromechanical camshaft adjuster (not shown in detail) of an internal combustion engine. Regarding the basic design and function of electromechanical camshaft adjusters, reference is made to the prior art cited at the beginning.

[0032] A housing 2 of the electric motor 1 comprises a housing shell 3 and a housing cover 4. The housing shell 3 is a sheet metal part made of sheet steel. In contrast, the housing cover 4 is a component of the electric motor 1 made of light metal, namely an aluminum alloy. In this case, the housing cover 4 is made of light metal sheet by deep drawing. Alternatively, the housing cover 4 could be manufactured by casting, for example.

[0033] A stator of a stator-rotor assembly 5 of the electric motor 1 comprises energizable windings 6 and is inserted into a recess 11 of the housing shell 3. The rotor of the electric motor 1 is designated overall by 7 and includes, among other components, a motor shaft 8 and a sensor ring 9, which is a component manufactured by deep drawing. After deep drawing, the sensor ring 9 is overmolded with plastic-bonded ferrite, thus providing a sensor surface for the sensor ring 9, which is designed as a multi-component component. An electronics module 10 is integrated into the electric motor 1.

[0034] The housing shell 3 forms a tab 12 with a rectangular basic shape, adjoining the recess 11. The width of the tab 12 corresponds at least to the radius of the recess 12. In the present case, the tab 12 is wider than the recess 11.

[0035] In this case, there are no mounting holes in the tab 12, which is simply described as rectangular. Three mounting tabs 13 arranged at various locations around the circumference of the housing shell 3 are aligned with mounting tabs 14 of the housing cover 4. The motor shaft 8 of the electric motor 1 is located inside the triangle defined by the mounting tabs 13, 14.

[0036] A torque transmission element 16 located outside the housing 2 is connected to the motor shaft 8.

[0037] The electronics module 10 is accommodated in the housing cover 4 and comprises a circuit board 17 with a triangular basic shape. Various components 18, 19, including several capacitors 19, are located on the circuit board 17. In the exemplary embodiment, all components 18, 19 are arranged on the side of the circuit board 17 facing the rotor 7 and the stator assembly 5. Adapted to the triangular basic shape of the circuit board 17, a V-shaped elevation 15 is visible on the outside of the housing cover 4. The tip of the V-shaped elevation is located near the fastening tabs 13, 14 which are diametrically opposite the rectangular tab 12. Starting from this, the V-shaped elevation 15 widens towards the rectangular tab 12.On the side of the widened end of the V-shaped elevation 15 there is a plug module 20 which is held in the housing cover 4, wherein form-fitting contours between the plug module 20 and the housing cover 4 are designated by 23.

[0038] Adhesive surfaces 24 are located on the surfaces of the connector module 20, which contact adhesive surfaces 25 on the housing cover 4. To establish electrically conductive connections, there are electrical contact surfaces 26 on the printed circuit board 17 and contact surfaces 27 on the connector module 20. Not visible in the figures are electrically conductive connections between the contact surfaces 26, 27 and insulation displacement contacts 21, which are located on the printed circuit board 17 and enable the supply of current to the windings 6. The insulation displacement contacts 21 are electrically conductively inserted into the printed circuit board 17 via a press fit and function as motor contacts within the electronics module 10.

[0039] In the exemplary embodiment, the housing shell 3 is permanently connected to the housing cover 4 by means of several positive-locking connections 22 produced by material deformation. Likewise, positive-locking connections 22 are formed between the connector module 20 and the housing cover 4, as well as between the printed circuit board 17 and the housing cover 4. Alternatively, rivets can be attached at the corresponding locations. Screw connections, however, are not provided. Both in the case of positive-locking connections 22, which are formed by deforming material of the housing shell 3 or the housing cover 4, and in the case of riveted connections, it is assumed that non-destructive disassembly of the electric motor 1 is not necessary. The electric motor 1 is an electronically commutated motor.

[0040] List of reference symbols

[0041] electric motor

[0042] Housing

[0043] Housing shell

[0044] Housing cover

[0045] Stator-rotor assembly

[0046] winding

[0047] rotor

[0048] Motor shaft

[0049] Sensor ring

[0050] Electronic module

[0051] Recess of the housing shell rectangular tab

[0052] Mounting tab of the housing shell

[0053] Mounting tab of the housing cover V-shaped elevation of the housing cover Torque transmission element, rotor-fixed Printed circuit board

[0054] Component, flat

[0055] capacitor, component

[0056] Plug module

[0057] Insulation displacement contact, motor contact

[0058] Form-fitting connection

[0059] Form-fitting contour

[0060] Adhesive surface on the connector module

[0061] Adhesive surface on the housing cover Electrical contact surface on the circuit board Electrical contact surface on the connector

[0062] stator

[0063] Stator carrier

[0064] Rolling bearing Paste, potting material Back of the circuit board Adhesive Coating of the circuit board Form-fit connection Deformation area Bearing shell Surrounding component Surrounding component

Claims

Patent claims 1 . An electric motor (1) comprising a multi-part housing (2) comprising a housing shell (3) in which a stator-rotor assembly (5) is located, and a housing cover (4) in which an electronic module (10) is accommodated, wherein the housing shell (3) has a circular recess (11) adapted to the shape of the stator-rotor assembly (5) and a tab (12) adjoining a portion of the edge of the recess (11) and describing a rectangle, wherein the width of the tab (12) corresponds at least to the radius of the recess (11), and wherein the housing cover (4) covers both the region of the recess (11) and said tab (12) and has a V-shaped plateau-like elevation (15) extending from the edge of the recess (11) facing away from the tab (12) into the region of the tab (12) and has a V-shaped, plateau-like elevation (15) corresponding to the electronic module (10). attributable printed circuit board (17),which widens according to the shape of the V-shaped elevation (15) from the recess (11) to the tab (12).

2. Electric motor (1) according to claim 1, characterized in that the housing shell (3) is designed as a sheet steel part and the housing cover (4) is designed as a light metal sheet part.

3. Electric motor (1) according to claim 1 or 2, characterized in that non-destructively releasable form-fitting connections (22) are formed between the housing cover (4) and at least one further component (3, 17) which is selected from the group of components (3, 17) comprising the housing shell (3) and the printed circuit board (17).

4. Electric motor (1) according to one of claims 1 to 3, characterized in that components (18) arranged on the circuit board (17) in the area which covers the stator-rotor assembly (5) are flatter than components (19) which are located in an area of the circuit board (17) covering the tab (12).

5. Electric motor (1) according to claim 4, characterized in that the flatter components (18) are assigned to a logic module and the comparatively tall components (19) are assigned to a power module, wherein signal and power lines to which the components (18) of the logic module or the components (19) of the power module are connected do not overlap.

6. Electric motor (1) according to one of claims 1 to 5, characterized by motor contacts pre-assembled on the circuit board (17), each formed by a combination of press-fit and insulation displacement contact (21).

7. Electric motor (1) according to one of claims 1 to 6, characterized by a plug module (20) held on the housing cover (4) by means of form-fitting contours (23).

8. Electric motor (1) according to one of claims 1 to 7, characterized in that it has a rotor (7) to which a sensor ring (9) is assigned, which is designed as a deep-drawn part and is overmolded with plastic-bonded hard ferrite.

9. Use of an electric motor (1) according to claim 1 in an electric camshaft adjuster of an internal combustion engine.

10. Use according to claim 9, characterized in that the internal combustion engine acts as a heat sink, with heat flowing from the electronic module (10) of the electric motor (1) to the internal combustion engine.

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