Contactless trigger with rotational magnetic sensor for a power tool

Patent metadata

Field	Value
Publication number	US-12491620-B2
Application number	US-202418914735-A
Country	US
Kind code	B2
Filing date	Oct 14, 2024
Priority date	May 13, 2019
Publication date	Dec 9, 2025
Grant date	Dec 9, 2025

Abstract

A trigger assembly for a power tool includes a housing, a moveable plunger extending from a surface of the housing, the movable plunger includes a first end disposed externally from the housing and a second end disposed internally within the housing. The trigger assembly further includes a trigger shoe coupled to the first end of the moveable plunger, and an arm including a first side that is moveably connected to the second end of the moveably plunger and a second side that is coupled to a magnet. The trigger assembly also includes a sensor configured to sense a magnetic field of the magnet. Movement of the trigger shoe rotates the magnet, and alters the magnetic field sensed by the sensor.

First claim

What is claimed is:

1 . A trigger assembly for a power tool comprising:
a moveable plunger having a first end and a second end, wherein the first end is coupled to a metallic member; a trigger shoe coupled to a second end of the moveable plunger; an inductive coil configured to generate a magnetic field; a sensor configured to sense the magnetic field; and wherein movement of the trigger shoe rotates the metallic member and alters a strength of the magnetic field sensed by the inductive sensor.

2 . The trigger assembly of claim 1 , wherein the sensor is electrically connected to a controller of the power tool, the controller configured to control an output of the power tool.

3 . The trigger assembly of claim 2 , wherein the sensor is configured to output a signal to the controller based on the sensed strength of the magnetic field.

4 . The trigger assembly of claim 3 , wherein the output is a voltage indicative of a position of the trigger shoe.

5 . The trigger assembly of claim 1 , wherein the metallic member is configured to rotate based on movement of an arm coupled to the second end of the moveable plunger.

6 . The trigger assembly of claim 5 , wherein the sensor is configured to sense a change in the strength of the magnetic field in response to the metallic member rotating with respect to the inductive coil.

7 . The trigger assembly of claim 1 , wherein the inductive coil and the metallic member are curved arcs, and wherein the magnetic member at least partially overlaps the inductive coil.

8 . The trigger assembly of claim 7 , wherein the rotation of the metallic member varies an overlap with the inductive coil causing a change in the magnetic field.

9 . A method for controlling an output of an electric power tool, the method comprising:
actuating a trigger shoe of the electric power tool in a first linear direction; converting linear movement of a movable plunger coupled to the trigger shoe into a rotational movement of a movable arm in a first rotational direction; inducing a magnetic field with an inductive coil; rotating a metallic member coupled to the movable arm in the first rotational direction; sensing a variation in a strength of the magnetic field in response to the rotation of the metallic member via a sensor; and controlling, via the controller, the output of the electric power tool based on the sensed variation in strength.

10 . The method of claim 9 , wherein the output of the electric power tool is a rotational speed.

11 . The method of claim 9 , wherein the sensor is configured to output a signal to the controller based on the sensed strength of the magnetic field.

12 . The method of claim 11 , wherein the output is a voltage indicative of a position of the trigger shoe.

13 . The method of claim 9 , wherein a sensor is configured to sense a change in the strength of the magnetic field in response to the metallic member rotating with respect to the inductive coil.

14 . The method of claim 9 , wherein the inductive coil and the metallic member are curved arcs and the magnetic member at least partially overlaps the inductive coil.

15 . A trigger assembly for a power tool comprising:
a moveable plunger having a first end and a second end, wherein the first end is coupled to a curved arc metallic member; a trigger shoe coupled to a second end of the moveable plunger; a curved arc inductive coil at least partially overlapping the curved arc metallic member thereby generating a magnetic field based on the overlap; and a sensor configured to sense the magnetic field;
wherein movement of the trigger shoe rotates the metallic member varies the overlap alters a strength of the magnetic field sensed by the inductive sensor.

16 . The trigger assembly of claim 15 , wherein the sensor is electrically connected to a controller of the power tool, the controller configured to control an output of the power tool.

17 . The trigger assembly of claim 16 , wherein the sensor is configured to output a signal to the controller based on the sensed strength of the magnetic field.

18 . The trigger assembly of claim 17 , wherein the output is a voltage indicative of a position of the trigger shoe.

19 . The trigger assembly of claim 15 , wherein the metallic member is configured to rotate based on movement of the moveable plunger.

20 . The trigger assembly of claim 15 , wherein the metallic member includes one or more of copper, iron, steel, and aluminum.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Merget Maxwell L
• Fieldbinder Douglas R
• Schneider Jacob P

Classifications

• H01H13/20

  Driving mechanisms · CPC title

• H01H13/14

  Operating parts, e.g. push-button · CPC title

• H01H3/50

  with indexing or locating means, e.g. indexing by ball and spring · CPC title

• H01H9/06

  Casing of switch constituted by a handle serving a purpose other than the actuation of the switch, e.g. by the handle of a vacuum cleaner · CPC title

• H03K17/97

  using a magnetic movable element · CPC title