# US 12,184,155 B2 · Electric tool, electric motor and rotor assembly thereof

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- Number: US 12,184,155 B2
- Document ID: US12184155B2
- Status: Granted
- Kind: B2
- Application number: 17/789,479
- Filed: 2020-12-24
- Published: 2023-02-09
- Granted: 2024-12-31
- Earliest claimed: 2019-12-27
- Assignees: Johnson Electric International AG
- Applicants: Johnson Electric International AG
- Inventors: Caiyong Zhang; Jinqiang Ju; Kar Wai Lam
- Web page: https://patentgrep.com/patent/US12184155B2

## CPC

- H02K 9/06: with fans or impellers driven by the machine shaft
- H02K 1/276: Magnets embedded in the magnetic core, e.g. interior permanent magnets [IPM]
- H02K 1/28: Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures
- H02K 7/145: {Hand-held machine tool}
- H02K 21/14: with magnets rotating within the armatures
- B25F 5/008: {Cooling means}
- H02K: DYNAMO-ELECTRIC MACHINES (dynamo-electric relays H01H53/00; conversion of DC or AC input power into surge output power {H03K3/53})
- B25F: COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR {(machines or arrangements of machines for performing specified combinations of different metal-working operations not covered by a single other subclass B23P23/00 and subgroups)}

## Abstract

The invention provides a power tool, a motor and a rotor assembly of the motor. The rotor assembly includes a rotating shaft, and a rotor body, a limiting member and a cooling fan fixed on the rotating shaft, the limiting member and the cooling fan are respectively arranged at both axial ends of the rotor body, the rotor body includes a rotor core and magnets fixed in the rotor core, the limiting member and the cooling fan jointly limit an axial displacement and a radial displacement of the magnets.

## Claims

### Claim 1

A rotor assembly comprising a rotating shaft, and a rotor body, a limiting member and a cooling fan fixed on the rotating shaft, the limiting member and the cooling fan respectively arranged at both axial ends of the rotor body, the rotor body comprising a rotor core and magnets fixed in the rotor core, wherein the limiting member and the cooling fan jointly limit an axial displacement and a radial displacement of the magnets, and wherein the cooling fan abuts first axial ends of the magnets, the cooling fan comprises protrusions integrally formed therewith and extending towards the rotor body, the protrusions abut the first axial ends of the magnets, the rotor core defines mounting holes for mounting the magnets, and positioning holes respectively communicated with the mounting holes, and further wherein each of the positioning holes is located on a center of a side of a corresponding one of the mounting holes facing the rotating shaft or away from the rotating shaft, the length of each positioning hole is shorter than the length of the corresponding mounting hole in the lengthwise direction of the corresponding mounting hole, the protrusions are at least partially inserted into the positioning holes to abut the magnets.

### Claim 2 (depends on 1)

The rotor assembly according to claim 1, wherein each protrusion comprises a stop portion, and the stop portion abuts against the first axial end of the corresponding magnet, to prevent the magnet from moving towards the cooling fan.

### Claim 3 (depends on 2)

The rotor assembly according to claim 2, wherein a radial dimension of one end of each protrusion close to the cooling fan is larger than a radial dimension of a free end of the protrusion to form the stop portion, the stop portion is an inclined surface or a step.

### Claim 4 (depends on 1)

The rotor assembly according to claim 1, wherein the cooling fan comprises a flange integrally formed therewith and extending toward the rotor body, the flange is deformed by the pressing of the rotor core during the installation of the rotor assembly, and at least partially abuts against the first axial ends of the magnets.

### Claim 5 (depends on 4)

The rotor assembly according to claim 4, wherein at least parts of the flange are embedded in bottoms of the mounting holes of the rotor core after being deformed to abut the magnets.

### Claim 6 (depends on 1)

The rotor assembly according to claim 1, wherein the limiting member abuts against second axial ends of the magnets opposite to the first axial ends directly or through an elastic washer.

### Claim 7 (depends on 1)

A motor, comprising a stator and the rotor assembly according to claim 1, wherein the rotor assembly is rotatably arranged in the stator.

### Claim 8 (depends on 7)

A power tool, comprising the motor according to claim 7.