Hydrostatic Ground Drive Control for Seamless Speed Range Transitions
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Solution Overview
Problem
Existing hydrostatic ground drive control systems for work machines like agricultural combines face challenges with mechanical transmissions requiring time-consuming and difficult transitions between speed ranges, especially under heavy loads or when stationary, and often have non-linear transitions due to multi-function handles with dead bands.
Innovation Solution
A control system utilizing a programmable processor-based controller for a hydrostatic ground drive with variable displacement pumps and motors, allowing for selectable speed ranges without mechanical transmissions, providing smooth transitions and automatic adjustments through an operator-controlled input device, ensuring seamless changes and overcoming the limitations of mechanical transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical transmission is used to provide discrete speed ranges, then selectable speed ranges are achieved, but transitions between speed ranges become time-consuming and difficult under heavy loads
Solution Approach 1:
The patent replaces the mechanical transmission system with a hydrostatic ground drive system using variable displacement pumps and motors controlled by a programmable controller. This substitution eliminates mechanical gear shifts and enables seamless, rapid transitions between speed ranges by simply adjusting hydraulic flow and motor displacement, directly resolving the time-consuming transition problem while maintaining selectable speed ranges.
Solution Approach 2:
The system uses variable displacement pumps and motors that can dynamically adjust their operating parameters in real-time. The programmable controller continuously monitors and adjusts the displacement of pumps and motors to maintain optimal performance across different speed ranges, enabling smooth and rapid transitions without the inertia and mechanical constraints of fixed-gear systems.
2Adaptability or versatility
If a mechanical transmission is used to provide discrete speed ranges, then selectable speed ranges are achieved, but transitions become difficult when the machine is stationary on a slope or under load
Solution Approach 1:
By replacing the mechanical transmission with a hydrostatic system, the patent eliminates the need for mechanical gear engagement under load. The variable displacement pumps and motors can change speed ranges smoothly through hydraulic control, making transitions easy and safe even when the combine is stationary on slopes or under heavy load, directly improving ease of operation.
Solution Approach 2:
The hydraulic fluid acts as an intermediary between the pump and motor, allowing for smooth, progressive adjustment of power transmission. This fluid coupling enables gradual displacement changes and speed transitions without the abrupt mechanical engagement required by gear shifts, making the system easier to operate under challenging conditions.
3Ease of operation
If multi-function handles with dead bands are used for speed control, then forward and reverse speed variation is achieved, but transitions through neutral position become non-linear and rough
Solution Approach 1:
The patent replaces the mechanical multi-function handle with electronic sensors and a programmable controller that read the handle position and digitally process the speed commands. This substitution eliminates the dead band and non-linear transitions inherent in mechanical linkages, providing smooth, linear, and precise speed control through neutral position by calculating appropriate pump and motor displacement values.
Solution Approach 2:
The system changes the control parameter from mechanical position through a dead band to electronic signal processing. The programmable controller uses algorithms to interpret handle position and generate smooth, linear displacement commands for the variable pumps and motors, eliminating the non-linearity and rough transitions caused by mechanical dead bands while maintaining full speed control capability.
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 quick, seamless, and automatic speed range changes without mechanical gear shifts, reducing operational delays and jerking, even under load conditions, and simulates neutral positions, enhancing operational efficiency and ease of use.
Implementation Method 1
a fluid pump operable for supplying pressurized fluid to one or more fluid motors
Implementation Method 2
hydrostatic ground drives for work machines such as agricultural combines
Implementation Method 3
fluid motors in driving relation, respectively, to the drive wheels of the vehicle
Data Source
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AI summary
The control system allows selecting from multiple speed ranges for the ground drive of a work machine (20) without a mechanical transmission. The system does this by controlling a variable displacement fluid pump (34) supplying fluid to variable displacement fluid motors (28, 30) driving ground wheels (22, 24) of the machine. When a speed range is selected, the system automatically controls displacement of the pump and motors to provide operability within the range by movement of a speed input device. When another range is selected, the system provides a seamless transition, including to and from reverse, as no disengaging and engaging of mechanical gears, or change in the speed input position, is required. The system can also automatically adjust ground speed for the new speed range for the current speed input position.