METHOD FOR THE THERMAL TREATMENT OF A COMPRESSED STRAND, METHOD FOR PRODUCING AN ELECTRIC MOTOR, AND METHOD FOR PRODUCING A MOTOR VEHICLE

Abstract

The present invention relates to a method for the thermal treatment of a compressed strand, where the thermal treatment of the compressed strand is carried out in a state installed as intended in a component of an electric motor, to a method for producing an electric motor with at least one component having at least one compressed strand, the compressed strand being thermally treated according to the invention, and to a method for producing a motor vehicle with an electric motor, the electric motor being produced according to the invention.

Claims

1. Method for the thermal treatment of a compressed strand, wherein the thermal treatment of the compressed strand is carried out in a state installed as intended in a component of an electric motor.

2. Method according to claim 1, wherein the thermal treatment is carried out a) after completion of said component b) after completion of said electric motor and prior to the installation of said electric motor into a vehicle, or c) after or during the initial operation of said vehicle with said electric motor.

3. Method according to claim 1, wherein the thermal treatment is recrystallization annealing or stress relief annealing.

4. Method according to claim 1, wherein said component of said electric motor is a stator or a rotor of said electric motor.

5. Method according to claim 1, wherein heating said compressed strand for thermal treatment is carried out by applying electric current to said compressed strand.

6. Method according to claim 1, wherein said compressed strand is equipped with an insulation material, where the thermal treatment is carried out at a temperature below the temperature resistance of said insulation material.

7. Method according to claim 1, wherein the thermal treatment is carried out at a temperature of 150-250° C.,

8. Method according to claim 1, wherein a single thermal treatment is carried out over a period of 30 to 300 minutes.

9. Method according to claim 1, wherein the cumulative thermal treatment period does not exceed a proportion of 10% of the operating time of said compressed strand.

10. Method according to claim 1, wherein the thermal treatment on said compressed strand takes place after completion of the electric motor and prior to the installation into a vehicle and that the thermal treatment on said compressed strand takes place at a temperature above the long-term temperature resistance of said insulation material.

11. Method according to claim 1, wherein the thermal treatment on said compressed strand takes place after or during the initial operation of said vehicle, respectively, and said compressed strand is heated by regulating or switching off the motor cooling and/or by idling load, as a result of intentionally applied leakage currents which generate heat but no torque.

12. Method according to claim 1, wherein the thermal treatment is repeated regularly.

13. Method according to claim 1, wherein compressed strands having a degree of compaction higher than 80% are used.

14. (canceled)

15. (canceled)

16. Method according to claim 1, wherein said compressed strand is equipped with an insulation material, where the thermal treatment is carried out at a temperature equal to the temperature resistance of said insulation material.

17. Method according to claim 1, wherein said compressed strand is equipped with an insulation material, where the thermal treatment is carried out at a temperature above the temperature resistance of said insulation material.

18. Method according to claim 1, wherein the thermal treatment is carried out at a temperature of 170°+−10° C.

19. Method according to claim 1, wherein the thermal treatment is repeated quarterly or annually.

Description

[0026] Further features and advantages of the present invention will become apparent from the following description of preferred embodiments with reference to the accompanying figures. Shown schematically in

[0027] FIG. 1 is a compressed strand in a side view provided for the thermal treatment according to the invention;

[0028] FIG. 2 is a compressed strand in a front view provided for the thermal treatment according to the invention;

[0029] FIG. 3 is a stator of an electric motor with compressed strands and end windings in a sectional side view;

[0030] FIG. 4 is a stator of an electric motor with compressed strands and interconnection webs in a front view;

[0031] FIG. 5 is an electric motor with a stator equipped with compressed strands in a side sectional view;

[0032] FIG. 6 is a motor vehicle with an electric motor equipped with compressed strands.

[0033] Reference is first made to FIG. 1.

[0034] A compressed strand 3 comprises substantially a number of wires 311, in particular copper wires or wires made of a copper alloy. Wires 311 are typically twisted together to form a wire package 31, and twisted wire package 31 is furthermore compacted, in particular, pressed to have a rectangular cross section. In addition, the individual wires are preferably provided with insulation, typically a varnish, and preferably the wire package is provided with insulation 32. Compressed strands typically have barrels at the ends that serve as an electrical and in particular a mechanical connection of the compressed strand.

[0035] An electric motor E, in particular an asynchronous motor, comprises substantially a stator 1 and a rotor 2 as the main components. One component of the electric motor, preferably the stator, but conceivably also the rotor, is preferably equipped with at least one compressed strand 3. The compressed strands used are preferably configured as rod-shaped Milliken conductors. The compressed strand is preferably installed into the component in a manner known to the person skilled in the art. The compressed strands can be connected to one another, for example, by way of interconnection webs 4. The component with the compressed strand(s) is assembled with other components to form an electric motor E. The electric motor is in turn installed into a vehicle K, preferably into a motor vehicle.

[0036] The thermal treatment can be carried out in different production stages, in particular [0037] a) after completion of the component, in particular the stator, [0038] b) after completion of the electric motor and prior to the installation of the electric motor into a vehicle, and/or [0039] c) after or during the initial operation of the vehicle with the electric motor.

[0040] The thermal treatment is preferably recrystallization annealing or stress relief annealing. Recrystallization annealing is to be understood to mean annealing without a phase change at a temperature in the recrystallization range after cold deformation. Stress relief annealing is to be understood to mean annealing without a phase change at a temperature below the recrystallization temperature after cold deformation.

[0041] The introduction of heat for thermal treatment of the compressed strand is preferably carried out by energizing the compressed strand, i.e., by having current act upon the compressed strand to be heated. (Symbols with wavy lines represent heat input.) The individual compressed strands can there be selectively heated, in particular individual circuits of compressed strands can be selectively acted upon with current for thermal treatment.

[0042] The quality of the thermal treatment process is substantially dependent upon the factors temperature and time. With regard to the temperature, it is noteworthy that compressed strand 3 is applied insulation material 32 which is damaged from a certain temperature, so that the time of the thermal treatment comes into focus. The maximum permissible temperature is in principle limited by the insulation material.

[0043] The temperature resistance of insulation material is typically divided into classes according to DIN EN 60085. Classes F (up to 155° C.) and H (up to 180° C.) are common in electric motors. Operation above this temperature does not lead to immediate failure of the insulation, but the insulation properties can (temporarily) deteriorate and the service life or resistance to aging can be reduced (permanently). This is acceptable to a certain extent, especially with sufficiently precise knowledge of the temperature-related aging behavior of an insulation material, while taking into account the product requirements.

[0044] In one configuration variant, annealing is therefore carried out at temperatures above the insulation class, where the cumulative annealing duration over the service life does not exceed 10% of the utilization time. Temperatures of 150-250° C., in particular 170°+−10° C., should be aimed for. Typical time intervals for thermal treatment are between 30-300 minutes.

[0045] Particular advantages can arise depending on the production stage at which thermal treatment is carried out.

[0046] For example, it can be provided that thermal treatment takes place after the completion of the electric motor and prior to the installation into a vehicle, and that thermal treatment takes place at an excessive temperature. Excessive temperature presently means a temperature above the temperature permitted by the insulation class. This aggressive variant in production has the advantage of provoking early failure of the system and to thereby prevent fault-prone products from being installed into the end product.

[0047] Thermal treatment of the compressed strand within the production line, i.e., after completion of the component or after completion of the electric motor and prior to the installation into the vehicle, can preferably be carried out in parallel with other quality tests so that the duration of the production process is not or only hardly extended by the thermal treatment of the compressed strand. The test run of the motor system during the final acceptance is preferred for this.

[0048] As already mentioned, the thermal treatment on the compressed strand can also take place after or during the vehicle's initial operation. This is preferably done by way of active temperature management. In order to keep the temperature high in time intervals when the motor is little used, active temperature management can comprise the following measures: a) intentionally lowering or even shutting off the motor cooling b) generating motor heat through idle load, e.g., as a result of intentionally applied leakage currents that generate heat but no torque. The annealing process is preferably repeated regularly, e.g., quarterly or annually, to prevent aging-related deterioration in the electrical conductivity. Depending on the application, the current supply should advantageously be selected such that there is presently torque occurring or there is presently no torque occurring (e.g., direct current does not generate any torque in an asynchronous machine). The proposed method is particularly suitable for compressed strands having a degree of compaction higher than 80%. The degree of compaction means the ratio of the wire area (copper wire and the insulating varnish surrounding it) to the smallest ensheathing of the compressed strand (excluding the main insulation).

[0049] Features and details described in the context of the method of course also apply in the context of a device described and vice versa, so that reference is or can always be made reciprocally with regard to the disclosure of the individual aspects of the invention.

LIST OF REFERENCE CHARACTERS

[0050] The following reference characters are used in the figures: [0051] K motor vehicle [0052] E electric motor [0053] 1 stator [0054] 2 rotor [0055] 3 compressed strand [0056] 4 interconnection web [0057] 31 wire packet [0058] 32 insulation [0059] 33 barrel [0060] 311 wire