Battery Array Positioning for Riding Mower Stability
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Solution Overview
Problem
Existing battery-operated riding rotary lawnmowers are not feasible or effective due to instability and balance issues caused by integrating multiple batteries and a single electric motor to drive rear wheels and rotary blades on a four-wheeled chassis.
Innovation Solution
Positioning a plurality of batteries in a U-shaped array around the chassis to maintain a low center of gravity and balance, with the electric motor connected to the batteries and a motor controller, allowing a single motor to drive both the rear wheels and rotary cutting blades.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electric motor is integrated to drive both rear wheels and rotary blades on a four-wheeled chassis, then the mower operates cleaner and with less maintenance, but the vehicle becomes unstable and unbalanced
Solution Approach 1:
The powertrain system is segmented into two separate electric motors: one motor (first motor) dedicated to driving the rear wheels through a first pulley and drive system, and another motor (second motor) dedicated to rotating the cutting blades through a second pulley and blade drive system. This segmentation allows independent optimization of each motor's function and placement, resolving the stability issue while maintaining the reliability benefits of electric propulsion.
2Reliability
If multiple batteries are integrated to power the electric motor, then the mower operates with less maintenance, but the center of gravity becomes unbalanced
Solution Approach 1:
The batteries are arranged in an asymmetric configuration where the majority of battery weight is positioned over the rear axle to counterbalance the forward position of the cutting deck and operator. This asymmetric weight distribution compensates for the unbalanced forces generated during cutting operations, maintaining vehicle stability while preserving the low-maintenance advantage of battery electric powertrains.
3Device complexity
If a single motor drives both wheels and blades, then the device complexity is reduced, but the ease of operation and control is compromised
Solution Approach 1:
The control system is segmented into independent control circuits for each motor: a first control circuit manages the wheel-driving motor's speed and torque for propulsion and steering, while a second control circuit manages the blade-rotating motor's speed for cutting performance. This segmentation simplifies the control logic for each function individually and improves overall ease of operation compared to a single motor attempting to perform both functions.
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
The solution results in a safe, stable, efficient, and cost-effective battery-operated riding rotary lawnmower that is durable and easy to maintain, with a system of drives that are inexpensive to replace and uses rechargeable batteries.
Implementation Method 1
The batteries are connected in series to each other and to an electric motor
Implementation Method 2
The motor has a first pulley to drive the rear wheels and a second pulley to operate rotary cutting blades
Data Source
AI summary
A riding lawnmower with a chassis having a rear portion with two rear wheels, and a cutting blade deck having one or more rotary blades. Batteries are positioned in a U-shaped array around the right side, left side, and rear end of the chassis, above and near the rear wheels to maintain a low center of gravity. The weight of the batteries is evenly distributed over the rear wheels to maintain balance. The batteries are connected in series to each other and to an electric motor. The electric motor is positioned within a central portion of the U-shaped array of batteries. A single electric motor drives both the rotary cutting blades and the rear wheels, which is made possible by placing the batteries near and above the rear wheels, and by positioning the electric motor under the seat.