Electric motor

Abstract

The disclosure relates to an electric motor comprising a base motor module and a plug module which is electrically and mechanically connected to the base motor module and is designed as an electronics module. The electronics module comprises a power electronics system, a driver electronics system and a control electronics system, and the electronics module and the base motor module each dissipate heat via separated heat paths. The disclosure further relates to an electric motor arrangement and also to a construction kit for electric motors.

Claims

1. An electric motor comprising: a base motor module; and a plug module electrically and mechanically connected to the base motor module, the plug module configured as an electronics module including: a power electronics system; a driver electronics system; and, a control electronics system; and, the base motor module configured to dissipate heat via a first heat path, and the electronics module configured to dissipate heat via a second heat path, the first heat path separate from the second heat path.

2. The electric motor of claim 1, wherein the base motor module includes a housing and a heat-conducting plate attached to the housing, the housing and heat-conducting plate forming at least a portion of the first heat path, and the heat-conducting plate configured to conduct heat from the base motor module to a heat sink.

3. The electric motor of claim 2, wherein the heat-conducting plate has a first flat surface configured to contact a component adjacent to the electric motor, the component configured as the heat sink.

4. The electric motor of claim 3, wherein the component has a second flat surface configured to engage the heat-conducting plate.

5. The electric motor of claim 2, wherein the heat-conducting plate forms a press fit with the housing of the electric motor.

6. The electric motor of claim 1, wherein the electronics module comprises an electronics housing and dissipates heat via the second heat path, wherein the second heat path is configured to flow through the electronics housing to an external heat sink.

7. The electric motor of claim 1, wherein the first and second heat paths are separated from one another by an insulating air space, and the insulating air space is formed between the base motor module and the electronics module.

8. The electric motor of claim 1, wherein the base motor module comprises: a housing pot; a stator; and, a rotor mounted in the housing pot via a rolling bearing, and the base motor module is inserted in the plug module, and electrical connections between the plug module and the base motor module are formed by joining the plug module and the base motor module together in an axial direction.

9. An electric motor arrangement for a variable valve train of an internal combustion engine, the arrangement comprising two electric motors, at least one of the two electric motors configured according to claim 1, and the two electric motors interconnected in a master-slave configuration.

10. An electric motor construction kit, comprising a base motor module and a plurality of selectable plug modules, each one of the plurality of selectable plug modules configured to be electrically and mechanically connected to the base motor module, and each one of the plurality of selectable plug modules being different from one another, wherein each one of the plurality of selectable plug modules is configured as an electronics module including: a power electronics system; a driver electronics system; and, a control electronics system, and, the base motor module configured to dissipate heat via a first heat path, and each one of the plurality of selectable plug modules configured to dissipate heat via a second heat path, the first heat path separate from the second heat path.

11. The electric motor of claim 1, wherein the first heat path exits a first axial end of the electric motor and the second heat path exits a second axial end of the electric motor.

12. The electric motor of claim 11, wherein the first heat path resides solely within the base motor module and the second heat path resides solely within the plug module.

13. The electric motor construction kit of claim 10, wherein each one of the plurality of selectable plug modules and the base motor module form an insulating air space, the insulating air space defining a beginning of the second heat path.

14. The electric motor construction kit of claim 13, wherein the base motor module includes a housing and a heat-conducting plate attached to the housing, the housing and heat-conducting plate forming at least a portion of the first heat path, and the heat-conducting plate configured to conduct heat from the base motor module to a heat sink.

15. The electric motor of claim 7, wherein the insulating air space defines a beginning of the second heat path.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In the following, an exemplary embodiment of the disclosure is explained in more detail by means of drawings. In the figures:

[0019] FIG. 1 shows a set for assembling electric motors, formed of a base motor module and various connector modules,

[0020] FIG. 2 shows a representation of the electric motor with a base module and an electronics module or plug module,

[0021] FIG. 3 shows a sectional view of the electric motor with two independent heat paths, and

[0022] FIG. 4 shows a sectional view of the electric motor with two independent heat paths before joining the two modules.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] FIG. 1 shows a construction kit, generally designated by the reference numeral 1, which is suitable for constructing various electric motors 2. The electric motors 2 are used in electromechanical camshaft adjusters, as are known in principle from the prior art mentioned.

[0024] The construction kit 1 is composed of a base motor module 3 and various plug modules 4, 5, 6. All core functions of the electric motor 2 are implemented in the base motor module 3. The structure of the base motor module 3 and a complete electric motor 2 can be seen in FIG. 3. A housing 7 of the base motor module 3 is configured as a housing pot made of sheet metal.

[0025] FIG. 2 illustrates the structure of the electric motor 2 in the joined configuration. A base motor module 3 is shown with a flange plate 8, which can be brought into contact with a motor-fixed component. Due to the flat contact, heat that is developed by the electric motor 2 can be dissipated. The power and control electronics systems for controlling the electric motor 2 are located in the electronics module 4, 5, 6.

[0026] FIG. 3 illustrates the structure in a sectional view. The heat path A is indicated with a dashed line, and the heat path B is indicated with a solid line. It can be clearly seen that the heat paths run separately from one another via an insulating air space 9.

[0027] Overall, the base motor module 3 is constructed as an inner rotor, wherein a stator 11, which has windings that can be energized, cooperates with a rotor 13 fastened on a shaft 14, i.e., a motor shaft. The rotor 13 has a pot shape that is open towards the housing base 9. A rotor base denoted by reference numeral 15 thus faces the end face of the base motor module 3 that faces away from the housing base 9. This is the end face of the base motor module 3 that is to be connected to one of the plug modules 4, 5, 6, as will be explained in more detail below. The rotor is equipped with permanent magnets 16. Overall, the base motor module 3 functions as a brushless DC motor. The permanent magnets 16 are embedded in a hollow cylindrical section of the rotor 13 which connects to the rotor base 15 and is slipped over the annular shoulder, i.e., overlaps with the latter in the axial direction.

[0028] The waste heat from the power electronics system and the waste heat from the motor windings are dissipated via separate heat paths A, B. The waste heat from the electric motor 2 is largely dissipated into a screw-on body, and the waste heat from the power electronics system is dissipated to the surroundings via an upstream heat sink.

[0029] The construction kit 1 with integrated control and driver electronics systems thus has two separate heat dissipation paths A and B in only one structural unit. This makes it possible to operate the electric motor 2 at high temperatures and still integrate the heat-sensitive electronics system of the motor control and motor driver stage.

[0030] The simplicity of assembly is achieved by a modularity of the system, in which the base motor is inserted into a flange plate 8 with a variable shape. The electronics module 4, 5, 6 is assembled separately. The “marriage” of the base motor module and the electronics module takes place only in the final assembly step.

[0031] This enables the motor control and the motor driver to be combined in one structural unit in the form of the construction kit 1 with an electric motor 2. This solution is designed for high temperatures and mechanical loads that occur on the internal combustion engine of a vehicle by ensuring the cooling. The system can be integrated into the vehicle with little development and installation space and can be used to automatically calculate all the required control variables for the electric motor 2.

[0032] For the waste heat from the electric motor coils to not generate any additional thermal load for the control and driver electronics systems, the electric motor 2 (heat source A) can be pressed into a flange plate 8 and thermally separated from the control board 10 by an insulating air space 9. The flange plate 8 can be mounted over a large area on the screw-on surface, for example on the internal combustion engine, so that the screw-on surface represents a heat sink for this heat source A. The heat path A accordingly leads from the coils through the stator insulation and the stator laminated core 11, via the motor housing into the flange plate 8 and then into the heat sink, the screw-on surface (see FIG. 3). The motor housing and the flange plate 8 can be made of steel in order to ensure a stable press fit even with high temperature fluctuations. In addition, the press fit serves to connect the motor housing to the flange plate 8 over a large area. Flattening the surfaces when joining the press fit increases the actual contact area and thus improves the heat conduction between the two joining partners.

[0033] This heat path A can be thermally separated from the power electronics system by an insulating air space 9. The waste heat generated by the power loss of the electronic components on the control board represents heat source B. This is dissipated via a second heat path B into a larger heat capacity, the electronics housing 12, and finally to the environment (see FIG. 3). The electronics housing 12 can consist of a very good heat-conducting material, such as aluminum, and can quickly absorb the waste heat generated suddenly in the electronic components and dissipate it to the surroundings via a generously dimensioned, rough surface. For better discharge of the waste heat into the heat capacity, components with particularly high power losses can be connected to the electronics housing 12 by using using heat-conducting paste. In addition, empty areas of the board can be connected to the electronics housing 12 with heat-conducting paste for better heat dissipation. Furthermore, the large surface area use of the heat-conducting paste serves to dampen the vibrations of the internal combustion engine coupled into the electric motor 2.

[0034] The control electronics system in particular, for example a microprocessor, is sensitive to heat and must be adequately protected against external heat input and its own waste heat must be dissipated. The separation of the heat dissipation of the two heat sources A and B via the heat paths A and B (see FIG. 3) enables this mechatronic system to operate even at high ambient temperatures. At least one microcontroller for generating the control signals for the motor driver is installed on the control board 10. The microcontroller processes the fed-in target values into the necessary control variables and control signals for the motor driver. The latter energizes the phases of the electric motor 2. There are also circuits for signal filtering and protective circuits on the board, as well as an optional sensor system.

[0035] According to the current prior art, welding or soldering techniques are primarily used to establish the electrical connection between the motor phases and the supply lines. The proposed concept uses insulation displacement contacts for contacting the coil wires and press-fit technology for connection to the control board 10. Both techniques result in a permanently pre-stressed contact, which offers higher vibration resistance and is produced by simple, mechanical joining processes. The contact pins in the plug of the plug module 4, 5, 6 are also contacted to the board by means of press-fit connections in order to achieve high vibration resistance here as well.

[0036] FIG. 4 illustrates the modular structure, whereby a common parts strategy can be implemented. The assembly can be divided into two parallel pre-assembly chains. The plug module 4, 5, 6, consisting of the plug connector, electronics housing 12 and control board 10, is constructed separately and thus enables variability with regard to the installation space geometry and the choice of the plug connector type (see FIG. 4). The electric motor with the electric motor stator 11, rotor 13 and output shaft 14 with output element can be preassembled in parallel (see FIG. 4). Subsequently, the electric motor 2 is pressed into the flange plate 8, which depicts the screw-on geometry and is finally mounted on the plug module 4, 5, 6 (electronics module) during the so-called “marriage”, wherein the electrical contact between the motor phases and the control board 10 is established simultaneously. This structure offers flexibility (the screw-on geometry, the housing and the plug interface) when using the common parts principle (by using a standardized base motor).

[0037] If a second, structurally identical or similar electric motor 2 is to be used, for example in the case of V engines or on intake and exhaust camshafts, the systems can be interconnected in a master-slave configuration. One system takes over the calculation of the controlled variables and controls itself as the master system and a second electric motor as the slave system.

[0038] Furthermore, an operating mode is possible in which two identical electric motors are used, which mutually monitor each other for correct function. In the event of a fault, the intact system can temporarily control the other faulty electric motor while the faulty system restarts. They thus mutually ensure their own operation by means of simple redundancy.

LIST OF REFERENCE CHARACTERS

[0039] 1 Construction kit [0040] 2 Electric motor [0041] 3 Base motor module [0042] 4 Plug module [0043] 5 Plug module [0044] 6 Plug module [0045] 7 Housing [0046] 8 Flange plate [0047] 9 Air space as insulation space [0048] 10 Control board [0049] 11 Stator laminated core [0050] 12 Electronics housing [0051] 13 Rotor [0052] 14 Output shaft [0053] 15 Rotor base [0054] 16 Permanent magnet [0055] 17 Heat-conducting plate