Hydrostatic Transmission Control Simulating Gear Drive
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Solution Overview
Problem
Operators of tractors and utility vehicles may find hydrostatic transmission controls unfamiliar or prefer traditional gear shift or automatic transmission controls, and manufacturers face higher costs due to the need for multiple transmission types to accommodate different operational modes.
Innovation Solution
A microcontroller-based transmission control system that provides alternative control interfaces and responses, simulating gear shift or automatic transmission modes by adjusting the swashplate angle of the hydrostatic transmission using proportional control valves and sensors, allowing operators to select between modes and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If multiple transmission types are provided to accommodate different operational modes, then operator preference and ease of operation are improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The hydrostatic transmission system is designed to perform multiple functions by simulating different transmission modes (manual gear shift and automatic transmission) through a single unified system. The microcontroller coordinates the hydrostatic transmission components to replicate the operational characteristics of both manual and automatic transmissions, eliminating the need for separate physical transmission systems while maintaining operator choice and preference
2Ease of manufacture
If a single hydrostatic transmission simulates multiple operational modes, then manufacturing costs and device complexity are reduced, but ease of operation may be compromised for operators unfamiliar with hydrostatic controls
Solution Approach 1:
The system dynamically adapts its control characteristics based on the selected operational mode. When in automatic transmission simulation mode, the microcontroller automatically adjusts transmission parameters without operator input. When in manual gear shift mode, the system responds to operator inputs on the accelerator pedal. This dynamic behavior allows the single hydrostatic transmission to mimic the familiar operational characteristics of both transmission types, making it accessible to operators regardless of their preference
3Adaptability or versatility
If foot pedals are used to control hydrostatic transmission, then infinite speed control and powered creep are achieved, but operators preferring gear shift control find it unfamiliar
Solution Approach 1:
The system replaces the direct mechanical linkage between foot pedals and transmission control with an electronic control system using proportional control valves and a microcontroller. This substitution allows the accelerator pedal to serve dual purposes: in automatic mode, it controls throttle while the microcontroller manages transmission ratios; in manual mode, it directly controls transmission ratio through proportional valve actuation. This mechanical-to-electronic substitution enables the system to replicate gear shift control characteristics while maintaining the benefits of hydrostatic transmission
Data Source
AI summary
A control apparatus is provided for a hydrostatic transmission to simulate a gear drive on a tractor. The hydrostatic transmission has a swashplate that is angularly movable to a plurality of positions, and a proportional valve that provides a control pressure to a servo piston to control the hydrostatic transmission swashplate position. A transmission control lever may be moved to a plurality of positions, each position providing a different voltage signal to a microcontroller. The microcontroller receives and converts a voltage signal to a coil current to actuate the proportional valve.