Electronic Slipping Belt Transmission Speed Control for Lawn Mowers
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Solution Overview
Problem
Existing slipping belt transmission systems in walk-behind lawn mowers do not allow for precise control of drive speed, particularly on smooth surfaces with low rolling resistance.
Innovation Solution
A transmission speed control system that includes a tiltable transmission with a motor and gear assembly, allowing for precise control of belt tension and thus drive speed, using a motor and gear assembly to adjust the angular position of the transmission between a minimum and maximum belt tension position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mechanical clutch cable system is used to control transmission engagement, then the transmission can be engaged or disengaged, but precise speed control is not achieved
Solution Approach 1:
The patent replaces the mechanical clutch cable system with an electronic control system comprising a sensor to detect transmission position, a microprocessor to process the position data, and an electronic actuator to adjust the transmission angle. This substitution enables precise speed control through electronic regulation of belt tension while maintaining ease of operation via electronic control mechanisms.
2Reliability
If belt tension is increased to reduce belt slip, then power transmission improves, but the transmission must be held in engaged state position
Solution Approach 1:
The patent implements a dynamic transmission positioning system where the transmission angle is continuously adjustable via an electronic actuator based on real-time sensor feedback and microprocessor control. This allows the system to dynamically optimize belt tension for reliable power transmission while enabling easy transition between engaged and disengaged states through electronic control signals, eliminating the need for manual mechanical manipulation.
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
Enables precise control of the lawn mower's driving speed by varying belt tension, improving speed regulation and reducing belt slip, allowing for accurate propulsion on various surfaces.
Implementation Method 1
a belt tension acting on a drive belt connecting the transmission and the engine is decreased to increase belt slip
Implementation Method 2
the belt tension acting on the drive belt connecting the transmission and the engine is increased to decrease belt slip
Implementation Method 3
The transmission is biased, e.g., via a return spring secured to a frame of the lawn mower, to tilt in the first direction
Implementation Method 4
The transmission positioning assembly includes a motor and a gear assembly secured to a frame of the lawn mower and the transmission
Data Source
AI summary
A transmission speed control system for a walk-behind lawn mower includes a transmission, a transmission positioning assembly, and an electronic control unit. The transmission is tiltable about and operably engaged with a drive axle shaft. The transmission positioning assembly tilts the transmission between first and second angular positions. A belt tension between a drive belt and a transmission pulley of the transmission continuously increases from a minimum belt tension when the transmission is in the first angular position to a maximum belt tension when the transmission is in the second angular position. The rotational drive force exerted on the drive axle shaft by the transmission and a resulting driving speed of the lawn mower vary proportionally with the belt tension. The electronic control unit controls the transmission positioning assembly to tilt the transmission based on target and detected driving speeds.