Ring element for a rotor of an electric motor

An electric power tool, comprising:

• an electric motor including a rotor with a rotor winding and an end plate, the rotor winding being laid in slots of a laminated rotor core, the end plate being positioned between the rotor winding and an end face of the laminated rotor core,
• wherein the end plate is a ring having a first side and a second side, the first side being placed against a lamellar insulating element on the end face of the laminated rotor core with the second side arranged facing the rotor winding and having a convex partial surface arranged radially about a central opening of the ring,
• wherein the partial surface has a radius of curvature configured to support the inner layer of the rotor winding such that a minimum bending radius of the inner layer of the rotor winding supported on the convex partial surface is maintained, and
• wherein the ring defines an inside diameter and an outside diameter such that a ratio of the outside diameter to the inside diameter lies in the range of 1.3 to 1.8,
• wherein a distance of the outside diameter of the ring to a rotor axis is the same or less than a distance of the bottom of the slots of the laminated rotor core to the rotor axis,
• wherein the first side of the ring-shaped body has at least one axial protrusion which is configured to be inserted into at least one corresponding recess in the lamellar insulating element, and
• wherein the axial protrusion comprises an insertion lug which is spaced apart from the central opening of the ring-shaped body.

An end plate for a laminated rotor core, comprising:

• a ring-shaped body having a circular outer perimeter shape without projections in a radial direction and having a first side and a second side, the first side being flat and configured to be placed against an outer facing surface of a lamellar insulating element arranged at at least one axial end region of a winding section of an electric motor rotor with the second side facing away from the electric motor, the second side of the ring-shaped body having a convex partial surface arranged radially about a central opening of the ring-shaped body,
• wherein the convex partial surface has a radius of curvature configured to support the inner layer of the rotor winding at the axial end region such that a minimum bending radius of the inner layer of the rotor winding supported on the convex partial surface is maintained,
• wherein a radius of curvature of the convex partial surface corresponds substantially to a thickness of the ring element,
• wherein the ring-shaped body defines an inside diameter and an outside diameter such that a ratio of the outside diameter to the inside diameter lies in the range of 1.3 to 1.8,
• wherein the first side of the ring-shaped body has at least one axial protrusion which is configured to be inserted into at least one corresponding recess in the lamellar insulating element, and
• wherein the axial protrusion comprises an insertion lug which is spaced apart from the central opening of the ring-shaped body.

A ring element comprising:

• a ring-shaped body configured as an end plate for a laminated rotor core, the ring-shaped body having a circular outer perimeter shape without projections in a radial direction and having a first side and a second side, the first side being flat and configured to be placed against a lamellar insulating element on an end face of an axial end region of the laminated rotor core with the second side facing away from the laminated rotor core, the second side of the ring-shaped body having a convex partial surface arranged radially about a central opening of the ring-shaped body,
• wherein the convex partial surface has a radius of curvature configured to support an inner layer of a rotor winding wound onto the laminated rotor core at the axial end region such that a minimum bending radius of the inner layer of the rotor winding supported on the convex partial surface is maintained,
• wherein the ring-shaped body defines an inside diameter and an outside diameter such that a ratio of the outside diameter to the inside diameter lies in the range of 1.3 to 1.8, and
• wherein the first side of the ring-shaped body has at least one axial protrusion which is configured to be inserted into at least one corresponding recess in the lamellar insulating element,
• wherein the axial protrusion comprises an insertion lug which protrudes from the second side adjacent the central opening of the ring-shaped body.