Mechanical IVT With Electric Pulley Control for Drive-By-Wire Mowers
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Solution Overview
Problem
Hydrostatic transmissions used in outdoor power equipment are not well-suited for drive-by-wire control systems, require regular maintenance, and can potentially overheat, necessitating periodic hydraulic fluid replacement.
Innovation Solution
A mechanical infinitely variable transmission (IVT) is employed, which includes a planetary gearset, a pulley system with a variable diameter pulley, and an actuator to control the pulley diameter electrically, allowing for precise speed control and reduced maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydrostatic transmissions are used to control drive wheels, then precise speed control and ease of operation are improved, but maintenance requirements increase and overheating risk occurs
Solution Approach 1:
The patent replaces the hydrostatic transmission system with a mechanical infinitely variable transmission (IVT) system that uses a planetary gearset combined with a variable ratio pulley system. This mechanical system eliminates hydraulic fluid and associated maintenance while providing continuous variable speed control through the interaction of the planetary gears and variable pulley mechanism.
Solution Approach 2:
The transmission system is divided into distinct functional modules: a planetary gearset for torque multiplication and direction control, a variable ratio pulley system for continuous speed variation, and a belt connection for power transmission. This segmentation allows each component to be optimized independently and simplifies maintenance.
2Ease of operation
If hydrostatic transmissions are used, then ease of operation is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the functions of torque multiplication (planetary gearset) and continuous variable ratio adjustment (variable pulley system) into a single integrated transmission mechanism. The planetary carrier connects the pulley system to the output, combining multiple functions in one compact assembly rather than requiring separate hydraulic and mechanical systems.
Solution Approach 2:
The planetary gearset serves multiple functions: torque multiplication, speed reduction, and providing mechanical advantage during the transition between different pulley ratios. The variable pulley system simultaneously controls both the gear ratio and the final output speed, reducing the need for additional control components.
3Measurement precision
If hydrostatic transmissions are used, then precise speed control is improved, but adaptability to drive-by-wire control systems worsens
Solution Approach 1:
The patent replaces the hydraulic control system with an electric actuator that directly controls the variable pulley ratio. This actuator receives electrical signals from drive-by-wire control systems and translates them into precise mechanical adjustments of the pulley diameters, enabling full electronic control while maintaining precise speed regulation.
Solution Approach 2:
The variable pulley system dynamically adjusts its ratio in response to electrical control signals, allowing real-time speed control without mechanical linkages. The continuous variability of the pulley ratio provides precise speed control comparable to hydrostatic systems while being fully compatible with electronic control architectures.
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 IVT provides improved efficiency, reduced maintenance needs, and lower manufacturing costs compared to hydrostatic transmissions, while enabling electrical control and adaptation to drive-by-wire systems.
Implementation Method 1
a pulley system comprising the input pulley and an output pulley linked via a belt, wherein one of the input pulley or the output pulley is a variable diameter pulley
Implementation Method 2
a planetary gearset comprising a sun gear, two or more planet gears, a carrier, and an annulus gear
Implementation Method 3
a planetary gearset comprising a sun gear, two or more planet gears, a carrier, and an annulus gear
Data Source
AI summary
Mechanical infinitely variable transmissions (IVTs) and vehicles employing such IVTs are discussed. The IVT can comprise a planetary gearset with a sun gear driven based on an input angular velocity and an annulus gear driven based on a combination of the input angular velocity and a variable gear ratio of a pulley system, wherein the variable gear ratio of the pulley system can be electrically controlled by an actuator. A drive element can be driven based on a carrier of the planetary gearset.