Safety switch for a battery pack powered trowel

Patent metadata

Field	Value
Publication number	US-12462990-B2
Application number	US-202318482988-A
Country	US
Kind code	B2
Filing date	Oct 9, 2023
Priority date	Oct 10, 2022
Publication date	Nov 4, 2025
Grant date	Nov 4, 2025

Abstract

Systems and methods for controlling a power trowel. A power trowel includes a handle including a speed control input, a housing, a shaft connecting the handle and the housing, a safety mechanism located on the shaft, a blade assembly positioned below the housing, a motor located within the motor housing and coupled to the blade assembly, and a controller. The safety mechanism includes a safety lever configured to move in response to an uncontrolled condition of the power trowel. The controller is connected to the motor and the safety mechanism. The controller is configured to drive, in response to actuation of the speed control input, the motor, detect a movement of the safety lever from a first position to a second position, and perform, in response to the movement of the safety lever to the second position, a safety operation.

First claim

What is claimed is:

1 . A power trowel comprising:
a handle including a speed control input; a housing; a shaft connecting the handle and the housing; a safety mechanism located on the shaft, the safety mechanism including a safety lever configured to move in response to an uncontrolled condition of the power trowel; a blade assembly positioned below the housing; a motor located within the housing and coupled to the blade assembly; a controller connected to the motor and the safety mechanism, the controller configured to:
drive, in response to actuation of the speed control input, the motor,
detect a movement of the safety lever from a first position to a second position, and
perform, in response to the movement of the safety lever to the second position, a safety operation.

2 . The power trowel of claim 1 , wherein the controller is located within the housing.

3 . The power trowel of claim 1 , wherein the safety mechanism further includes a position sensor configured to detect a position of the safety lever.

4 . The power trowel of claim 3 , wherein the controller is configured to detect the movement of the safety lever based on a signal from the position sensor.

5 . The power trowel of claim 1 , further comprising:
a power switch located on the handle, and wherein the controller is configured to:
drive, in response to actuation of the speed control input, the motor when the power switch is in a first power switch position, and
ignore actuation of the speed control input when the power switch is in a second power switch position.

6 . The power trowel of claim 1 , wherein an amount of power provided to the motor to drive the motor is based on an amount of actuation of the speed control input.

7 . The power trowel of claim 1 , wherein the speed control input includes a lever portion configured to actuate a plunger switch.

8 . The power trowel of claim 1 , further comprising:
a battery pack interface configured to receive a battery pack, the battery pack interface configured to provide power to the motor, and wherein the controller is configured to perform the safety operation by disconnecting the battery pack from the motor.

9 . The power trowel of claim 1 , wherein the controller is configured to perform the safety operation by braking the motor.

10 . The power trowel of claim 1 , wherein the controller is further configured to:
detect a second movement of the safety lever from the second position to the first position; and stop, in response to the safety lever being in the first position, performing the safety operation.

11 . A power trowel comprising:
a handle including a speed control input; a housing; a shaft connecting the handle and the housing; a blade assembly positioned below the housing; a motor located within the housing and coupled to the blade assembly; and a safety mechanism located on the shaft, the safety mechanism including:
a safety lever configured to move from a first position to a second position in response to an uncontrolled condition of the power trowel,
a sensor configured to sense whether the safety lever is in the first position or the second position, and
a retaining portion configured to retain the safety lever in the second position.

12 . The power trowel of claim 11 , wherein the speed control input includes a lever portion configured to actuate a switch.

13 . The power trowel of claim 12 , wherein the speed control input includes a compression spring configured to maintain a position of the lever portion.

14 . The power trowel of claim 11 , further comprising:
a battery pack interface configured to receive a battery pack, and wherein the battery pack interface is configured to provide power to the motor.

15 . A power trowel comprising:
a handle; a housing; a shaft connecting the handle and the housing; a safety mechanism located on the shaft, the safety mechanism including a safety lever configured to move in response to an uncontrolled condition of the power trowel; a motor located within the housing; and a controller connected to the motor and the safety mechanism, the controller configured to:
detect a first movement of the safety lever from a first position to a second position,
lock, in response to the first movement of the safety lever to the second position, operation of the motor,
detect a second movement of the safety lever from the second position to the first position, and
permit, in response to the second movement of the safety lever to the first position, operation of the motor.

16 . The power trowel of claim 15 , wherein the safety mechanism further includes a position sensor configured to detect a position of the safety lever.

17 . The power trowel of claim 16 , wherein the position sensor includes a microswitch configured to provide an output to the controller in response to the safety lever contacting the microswitch.

18 . The power trowel of claim 15 , wherein the safety mechanism further includes a retaining portion configured to retain the safety lever in the second position.

19 . The power trowel of claim 18 , wherein the retaining portion includes a magnet configured to magnetically attract the safety lever.

20 . The power trowel of claim 15 , further comprising:
a battery pack interface configured to receive a battery pack, the battery pack interface configured to provide power to the motor, and wherein the controller is further configured to lock operation of the motor by disconnecting the battery pack from the motor.

Assignees

• Milwaukee Electric Tool Corp

Inventors

• Gleason Brennen M
• Hendryx Caleb R
• Reed Michael C
• Armendariz Julio C

Classifications

• H01H2009/068

  with switches mounted on a handlebar, e.g. for motorcycles, fork lift trucks, etc. · CPC title

• H01H2009/065

  Battery operated hand tools in which the battery and the switch are directly connected · CPC title

• H01H21/10

  Casing of switch constituted by a handle serving a purpose other than the actuation of the switch · CPC title

• E04F21/248 Primary

  used by an operator walking behind the trowel, i.e. walk-behind power trowels · CPC title

• H01M50/247

  specially adapted for portable devices, e.g. mobile phones, computers, hand tools or pacemakers · CPC title