Lawnmower Bail Bar Position Sensing for Blade Motor Interlock
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Solution Overview
Problem
Electronic lawnmowers lack a mechanism to ensure the blades and drive motors stop operating when the bail bar is not gripped by a user, posing a safety concern.
Innovation Solution
Implementing a position sensor and controller system to determine the position of the bail control bar, ensuring the blade motor operates only when the bail control bar is in a closed position, using a Hall effect sensor assembly to detect the bail control bar's position and control the blade motor accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an electronic lawnmower uses battery power without a mechanical fuel-cutoff mechanism, then the lawnmower achieves cleaner operation and easier maintenance, but the safety mechanism to stop blade and motor operation when the bail bar is released becomes insufficient
Solution Approach 1:
The patent replaces the traditional mechanical fuel-cutoff mechanism with an electronic control system. A position sensor detects the bail bar position and sends signals to a controller, which then controls the blade motor and drive motor through electrical circuits. This substitution eliminates the need for mechanical linkages and fuel cutoffs, simplifying the structure while maintaining safety through electronic monitoring and control.
2Reliability
If a mechanical linkage is used to couple the bail bar to the prime mover, then the safety function is reliable, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical linkages with a simplified electronic sensing and control system. A position sensor (such as a Hall effect sensor or limit switch) directly detects the bail bar position without requiring mechanical coupling to the prime mover. The controller processes this signal and independently controls the blade motor and drive motor, reducing mechanical complexity while maintaining safety reliability.
Solution Approach 2:
The patent introduces an electronic intermediary (the position sensor and controller) between the bail bar and the prime mover. Instead of direct mechanical coupling, the sensor acts as an intermediary that detects bail bar position and communicates this information to the controller, which then mediates the control of the motors. This intermediary approach simplifies the mechanical structure while ensuring safety through electronic control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures safe operation by preventing the blade and drive motors from engaging unless the bail control bar is gripped, enhancing user safety and operational control.
Implementation Method 1
a Hall effect sensor assembly configured to determine a position of the bail control bar. The Hall effect sensor assembly includes a Hall effect sensor and a magnet.
Data Source
AI summary
A battery powered lawnmower having a blade motor coupled to at least one blade, an input configured to receive an activation input from a user, and a bail control bar. The bail control bar is coupled to a position sensor configured to determine a position of the bail control bar. The battery powered lawnmower further includes a controller coupled to the position sensor and configured to control an operation of the blade motor. The controller is configured to receive a blade motor control command resulting from the activation input received by the input, and determine a position of the bail control bar based on data provided by the position sensor. The controller is further configured to, in response to determining that the bail control bar is in a closed position, control the blade motor based on the received blade motor control command.