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EP-3510693-B1 - A METHOD AND ARRANGEMENT FOR ASSEMBLING AN ELECTRIC MOTOR OR GENERATOR

EP3510693B1EP 3510693 B1EP3510693 B1EP 3510693B1EP-3510693-B1

Inventors

  • BROADBRIDGE, Samuel

Dates

Publication Date
20260506
Application Date
20170901

Claims (9)

  1. A method of assembling an electric motor or generator having an annular first element mounted on a circumferential mounting surface of a second element, the method comprising measuring the axial height of the annular first element; placing a heating coil (500) within an inner annular surface of the annular first element; applying a current to the heating coil to heat the inner annular surface of the annular first element to a temperature that results in the inner annular surface of the annular first element increasing in diameter to allow the annular first element to be mounted on or over the circumferential mounting surface of the second element; mounting the annular first element on or over the circumferential mounting surface of the second element; and cooling the annular first element to form an interference fit between the annular first element and the circumferential mounting surface of the second element, wherein the mounting of the annular first element on or over the circumferential mounting surface of the second element involves axially positioning the annular first element on the circumferential mounting surface dependent upon the axial height of the annular first element, wherein the annular first element is a back iron (610) and the second element is a stator support element (253), or wherein the annular first element is a rotor and the second element is a back iron (110), or wherein the annular first element is a back iron and the second element is a rotor, or wherein the first element is a stator support element and the second element is a back iron.
  2. A method according to claim 1, wherein the heating coil is an induction coil.
  3. A method according to claim 1, wherein the back iron is arranged to receive rotor magnets.
  4. A method according to claim 1,wherein the back iron includes or is arranged to receive stator teeth.
  5. A method according to any one of claims 1, wherein the back iron is formed from electrical steel, wherein the back iron is arranged to form part of a magnetic circuit within the electric motor or generator.
  6. A method according to any one of claims 1, wherein the back iron includes a plurality of circumferential laminations of electrical steel.
  7. A method according to any one of the preceding claims, wherein the diameter of the inner annular surface of the first element is equal to or smaller than the diameter of the circumferential mounting surface of the second element when the annular first element and the second element are at the same temperature.
  8. A method according to claim 1, further comprising mounting the annular first element on the circumferential mounting surface of the second element at a predetermined radial position to allow electrical coupling of coil windings mounted on the annular first element to a control device mounted on the second element.
  9. An arrangement for assembling an electric motor or generator having an annular first element mounted on a circumferential mounting surface of a second element, the arrangement comprising means arranged to perform the steps of any one of claims 1 to 8.

Description

The present invention relates to a method and arrangement for assembling an electric motor or generator, in particular the mounting of a back iron on or in a stator and the mounting of a back iron in or on a rotor. Electric motors, and particularly in-wheel electric motors, contain a number of components that need to be securely connected or attached together. The connection must be secure, but there are further considerations because electric motors are often finely tuned for optimum operational characteristics. For example, the distance between the rotor and the stator, between which a magnetic field is generated, should ideally be uniform about the entirety of the rotor/stator. At the same time, electric motors are often exposed to heavy vibrations and must be able to operate satisfactorily under such conditions. There are components of electric motors that have certain magnetic properties. These components, which will be referred to as magnetic components, may include the back iron of a stator or the back iron of a rotor. The materials of these components are chosen primarily for their magnetic properties, in particular having a low reluctance, for example electrical steel. Typically, to inhibit eddy currents resulting from flux flowing through the materials these components are usually manufactured using a number of laminations stacked together. It is often necessary to attach such magnetic components to corresponding structural components, whose materials are chosen primarily to exhibit other properties such as structural rigidity or good heat conductance. For example, the stator will typically include a magnetic component in the form of a back iron having a set of teeth wound with coil windings. The stator may also include a structural element such as a heat sink that is also arranged to conduct heat away from the stator teeth. Likewise, the rotor will typically include a set of permanent magnets mounted on a back iron that needs to be connected to a rotor housing. One known solution for connecting together magnetic and structural components of an electric motor involves creating an interference fit between the respective components by heating up one of the components in an oven to a temperature that allows the component to be mounted on or over a circumferential mounting surface on the other component, whereupon cooling of the heated component the diameter of the component contracts around the circumferential mounting surface of the other component. However, the process of heating the component in an oven can be time consuming and the need to remove the component from the oven increases the complexity of the manufacturing process. EP 0 645 873 A1 describes a method and apparatus for attaching rotors to crankshafts. In accordance with an aspect of the present invention there is provided a method and arrangement according to the accompanying claims. The present invention as claimed has the advantage of simplifying the manufacturing process for an electric motor or generator while also reducing the time required to assemble an electric motor or generator. The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates an exploded view of an assembled electric motor;Figure 2 is an exploded view of the motor of Figure 1 from an alternative angle;Figure 3 illustrates an exploded view of a rotor according to an embodiment of the present invention;Figure 4 illustrates a rotor according to an embodiment of the present invention;Figure 5 illustrates a rotor assembly arrangement according to an embodiment of the present invention;Figure 6 illustrates an exploded view of a stator according to an embodiment of the present invention;Figure 7 illustrates a stator according to an embodiment of the present invention;Figure 8 illustrates a stator assembly arrangement according to an embodiment of the present invention;Figure 9 illustrates a stator assembly arrangement according to an embodiment of the present invention;Figure 10 illustrates a stator assembly arrangement according to an embodiment of the present invention;Figure 11 illustrates a stator assembly arrangement according to an embodiment of the present invention. The embodiment of the invention described is an arrangement for assembling a motor or generator by mounting an annular first element on or over a circumferential mounting surface of a second element. Examples of such elements include the mounting of a rotor housing on a back iron and the mounting of a back iron on a stator support element, for example a stator heat sink, for an outer rotor motor configuration. Alternatively, the mounting of a back iron onto a rotor housing and the mounting of a stator support element on a back iron for an inner rotor motor configuration. For the purposes of the present embodiment the electric motor being assembled is for use in a wheel of a vehicle, however the electric motor may be locate