Outer rotor brushless motor stator mount

Patent metadata

Field	Value
Publication number	US-11670977-B2
Application number	US-202016856762-A
Country	US
Kind code	B2
Filing date	Apr 23, 2020
Priority date	Apr 24, 2019
Publication date	Jun 6, 2023
Grant date	Jun 6, 2023

Abstract

A brushless direct-current motor is provided includes an inner stator and an outer rotor. A rotor shaft extends through a stator core of the inner stator. A first end cap includes a radial back plate disposed on a first side of the stator and a front center opening through which the rotor shaft is supported via a front bearing. A second end cap includes an inner annular body extending axially inwardly and forming a rear center opening, an outer annular body, and a main body extending on a second side of the stator. The inner annular body includes a first portion that extends at least partially into an opening of the stator core and supports the rotor shaft via a rear bearing, and a second portion rearward of the first portion that received a rear end of the rotor shaft therein and houses a sensor board therein.

First claim

The invention claimed is:

1. A brushless direct-current (BLDC) motor comprising:
a rotor shaft extending along a center axis;
a stator having a stator core, a plurality of teeth extending radially outwardly from the stator core, a plurality of windings wound around the stator teeth, a stator collar mounted on the stator core, and a plurality of terminals mounted on the stator collar in a direction parallel to the longitudinal axis and electrically coupled to the plurality of windings;
a rotor having a rotor core disposed around the stator, a plurality of permanent magnets secured to the rotor core, and an inner annular member mounted on the rotor shaft;
a first end cap including a radial back plate disposed on a first side of the stator and having a front center opening through which the rotor shaft is supported via a front bearing; and
a second end cap having an inner annular body, an outer annular body, and a main body extending on a second side of the stator from the inner annular body to the outer annular body, the inner annular body extending axially inwardly and forming a rear center opening, wherein the inner annular body includes a first portion that extends at least partially into an opening of the stator core and supports the rotor shaft via a rear bearing radially intersecting at least a portion of the stator, and a second portion rearward of the first portion that receives a rear end of the rotor shaft therein and houses a sensor board therein, the sensor board accommodating at least one positional sensor facing the end of the rotor shaft,
wherein the second end cap further comprises a plurality of openings formed in the main body around the inner annular body for passage of the plurality of terminals so distal ends of the plurality of terminals project outside the second end cap, wherein a radial plane passing through the sensor board intersects the plurality of terminals.

2. The motor of claim 1 , wherein the rotor comprises a plurality of radial blades extending angularly from the rotor core to the inner annular member forming a fan adjacent the stator that generates an airflow with rotation of the rotor shaft.

3. The motor of claim 2 , wherein the radial back plate of the first end cap includes at least one sloped surface forming at least one air gap, wherein the airflow generated by the fan is centrifugally guided within the first end cap by the at least one sloped surface and caused to exit the first end cap through the at least one air gap, and wherein the first end cap includes an annular outer body having at least one exhaust port in fluid communication with the at least one air gap and through which the airflow is expelled from the first end cap in a substantially radial direction.

4. The motor of claim 1 , wherein the annular body of the second end cap extends form the main body around at least a portion of the rotor core and comes into contact with the first end cap to secure the second end cap to the first end cap around the rotor.

5. The motor of claim 2 , wherein the second end cap comprises a plurality of air passage openings for passage of the airflow, wherein the plurality of air passage openings is radially inward of the plurality of openings.

6. The motor of claim 1 , wherein the first portion of the inner annular body has a larger diameter at the first portion that at the second portion.

7. The motor of claim 6 , further comprising a sense magnet mounted on the rear end of the rotor shaft in close proximity to the sensor board.

8. The motor of claim 7 , wherein the inner annular body further includes a third portion disposed between the first portion and the second portion and having a diameter that is greater than that of the second portion but smaller than that of the first portion, the sense magnet being located within the third portion of the inner annular body.

9. The motor of claim 1 , wherein the inner annular body further comprises a radial rim formed at a rear end of the second portion, wherein the sensor board is secured to the radial rim.

10. The motor of claim 1 , further comprising at least one of an impact absorbing member or a spring disposed between the sensor board and the radial rim.

11. The motor of claim 1 , wherein the second end cap is provided with one or more deflection limiting members near meeting boundaries of the outer annular body and the main body, the one or more deflection limiting member facing the rotor core to absorb an impact of the rotor core in an even of a pivoting movement of the rotor shaft away from the center axis.

12. A power tool comprising:
a housing;
a battery receptacle formed on the housing for receiving a power tool battery pack;
a control module disposed within the housing to control supply of power from the battery pack; and
a brushless direct-current (BLDC) motor mounted within or on the housing, the motor comprising:
a rotor shaft extending along a center axis;
a stator having a stator core, a plurality of teeth extending radially outwardly from the stator core, a plurality of windings wound around the stator teeth, a stator collar mounted on the stator core, and a plurality of terminals mounted on the stator collar in a direction parallel to the longitudinal axis and electrically coupled to the plurality of windings;
a rotor having a rotor core disposed around the stator, a plurality of permanent magnets secured to the rotor core, and an inner annular member mounted on the rotor shaft;
a first end cap including a radial back plate disposed on a first side of the stator and having a front center opening through which the rotor shaft is supported via a front bearing; and
a second end cap having an inner annular body, an outer annular body, and a main body extending on a second side of the stator from the inner annular body to the outer annular body, the inner annular body extending axially inwardly and forming a rear center opening, wherein the inner annular body includes a first portion that extends at least partially into an opening of the stator core and supports the rotor shaft via a rear bearing radially intersecting at least a portion of the stator, and a second portion rearward of the first portion that receives a rear end of the rotor shaft therein and houses a sensor board therein, the sensor board accommodating at least one positional sensor facing the end of the rotor shaft,
wherein the second end cap further comprises a plurality of openings formed in the main body around the inner annular body for passage of the plurality of terminals so distal ends of the plurality of terminals project outside the second end cap, wherein a radial plane passing through the sensor board intersects the plurality of terminals.

13. The power tool of claim 12 , wherein the power tool further comprises:
a tubular cylinder housed within the housing defining a longitudinal axis;
a piston reciprocatingly disposed within the tubular cylinder;
a crank mechanism disposed within the housing configured to convert a rotary motion to a reciprocating motion for driving the piston;
a tool holder mounted on the housing forward of the tubular cylinder; and
a battery receptacle provided on the housing for receiving a removable power tool battery pack, the battery pack being provided on a first side of a plane that intersects the longitudinal axis when received within the battery receptacle,
wherein the motor is mounted on the housing on a second side of the plane that intersects the longitudinal axis such that a distance between the longitudinal axis and a center of gravity of the power tool with the battery pack received within the battery receptacle is less than or equal to approxim

Assignees

• Black & Decker Inc

Inventors

• Fogle John B
• Jeffries Dustin
• Marjomaa Michael R
• Pulley Kevin L
• Zou Vincent W
• Dunston Jarrett A
• Smith David J
• Thieme Rene
• Heimrich Tim
• Heep Tobias
• Bernhart Daniel
• Schmidtfrerick Dieter

Classifications

• B25D11/125

  with a fluid cushion between the crank drive and the striking body · CPC title

• H02K9/06

  with fans or impellers driven by the machine shaft · CPC title

• H02K15/03

  having permanent magnets · CPC title

• H02K1/28

  Means for mounting or fastening rotating magnetic parts on to, or to, the rotor structures · CPC title

• H02K7/14

  Structural association with mechanical loads, e.g. with hand-held machine tools or fans (with fan or impeller for cooling the machine H02K9/06) · CPC title