Tractor Hydraulic Pump Speed and Transmission Ratio Control
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Solution Overview
Problem
Tractors face challenges in delivering high flow rates of hydraulic fluid to auxiliary equipment when the engine-driven pump's capacity is insufficient at current engine speeds, leading to inefficiencies in controlling auxiliary equipment like front loaders.
Innovation Solution
A tractor with an electronically controlled transmission and a driver-operated control system that adjusts engine speed and transmission ratio to maintain consistent tractor speed while delivering the required oil flow rate to auxiliary outlets, using a combination of an engine-driven hydraulic pump and solenoid-operated spool valves controlled by a driver-operated control means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the engine speed is increased to deliver high flow rates to auxiliary equipment, then the hydraulic pump can provide sufficient oil flow rate, but the tractor speed increases which may not be desired by the driver
Solution Approach 1:
The transmission operative ratio is dynamically adjusted in response to hydraulic fluid flow rate demands. When high flow rates are required for auxiliary equipment, the system automatically changes the transmission ratio to compensate for engine speed changes, thereby maintaining substantially constant tractor speed while delivering the required hydraulic flow rate.
Solution Approach 2:
The control system continuously monitors the operative ratio of the transmission and adjusts it based on the flow rate demands from auxiliary outlets. This feedback mechanism ensures that the transmission ratio is optimized to maintain constant tractor speed while meeting the hydraulic flow requirements of auxiliary equipment.
2Speed
If the transmission operative ratio is changed to maintain constant tractor speed, then the tractor speed remains substantially unchanged, but the engine speed must be adjusted which complicates the control system
Solution Approach 1:
The electronically controlled transmission system serves multiple functions: it controls tractor speed and simultaneously manages engine speed to meet hydraulic flow demands. By integrating these functions into a single control system, the patent reduces overall system complexity despite the additional control requirements.
3Adaptability or versatility
If a CVT is used to precisely control the transmission ratio, then the exact appropriate transmission can be selected, but the device complexity and cost increase
Solution Approach 1:
The system changes the operative ratio parameter of the transmission based on hydraulic fluid flow rate demands. By using an electronically controlled transmission that can adjust the operative ratio parameter, the system achieves precise control over tractor speed while meeting hydraulic flow requirements, whether through CVT or electronically controlled discrete ratios.
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 the tractor to maintain consistent speed and deliver the necessary hydraulic fluid flow rates to auxiliary equipment, ensuring efficient operation of attachments like front loaders by optimizing engine speed and transmission ratio based on operator input.
Implementation Method 1
an engine driven hydraulic pump which provides pressurised fluid to one or more auxiliary outlets on the tractor
Implementation Method 2
solenoid-operated spool valves controlled by a driver-operated control means
Data Source
AI summary
A tractor has an engine which drives the tractor via a transmission whose operative ratio is controlled electronically. The tractor also has an auxiliary hydraulic fluid supply system with an engine driven hydraulic pump which provides pressurized fluid to one or more auxiliary outlets on the tractor. A driver operated control means is provided for selecting the oil flow rate to be delivered to the outlets, and a control system adjusts the speed of the engine to the minimum required to provide the selected oil flow rate and changes the operative ratio of the tractor transmission so that the speed of the tractor remains substantially unchanged despite any change in engine speed required to deliver the selected oil flow rate. The transmission may be a CVT or powershift transmission.