Tractor Automatic Steering Hydraulic Control
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Solution Overview
Problem
Hydrostatically steered windrowers face instability at high speeds, leading to loss of control in situations like slight downhill conditions, where there is no flow to the motors, causing uncontrolled movement.
Innovation Solution
An automatic steering system for a hydraulically driven tractor that includes a guidance controller, hydraulic control valve arrangement, and a double-acting hydraulic control cylinder, which uses position information to control the flow of hydraulic fluid to the driven wheels, ensuring stable steering and speed control, with a bypass valve for manual override and pressure reduction to prevent uncontrolled movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the tractor uses hydrostatic steering with drive wheels ahead of castor wheels (cab forward), then the tractor can transport at higher speeds, but the tractor becomes unstable and loses control in situations like slight downhill conditions
Solution Approach 1:
The patent implements a dynamic wheel configuration where the tractor can switch between cab forward and engine forward positions. The system dynamically adjusts the relative positions of drive wheels and castor wheels based on operating conditions, allowing the tractor to achieve both high-speed stability in engine forward mode and controlled maneuverability in cab forward mode.
Solution Approach 2:
The patent changes the structural parameter of wheel arrangement by allowing the tractor to operate in two distinct configurations: cab forward with drive wheels ahead (for high speed) and engine forward with castor wheels leading (for stability). This parameter change enables the system to optimize performance for different operating scenarios.
2Stability of the object's composition
If the tractor operates in engine forward position with castor wheels leading, then the tractor achieves high stability and can travel at higher speeds, but the steering control becomes more complex requiring precise differential speed control
Solution Approach 1:
The patent implements self-steering functionality where the tractor automatically maintains its course using castor wheels that naturally follow the direction of travel. The system reduces the need for complex manual steering inputs by allowing the castor wheels to self-align and guide the tractor, thereby simplifying the overall steering control mechanism while maintaining stability.
Solution Approach 2:
The patent replaces complex mechanical steering linkages with a hydraulic differential control system that regulates speed differences between wheels. This substitution uses hydraulic pressure control instead of mechanical steering geometry, simplifying the control mechanism while enabling precise differential speed adjustment for stable operation.
3Ease of operation
If the hydraulic control valve arrangement is used to control steering, then precise steering control is achieved, but the system loses control when there is no flow to the motors (e.g., in slight downhill situations)
Solution Approach 1:
The patent introduces an intermediary control mechanism that monitors hydraulic flow conditions and activates alternative control modes when flow is insufficient. This intermediary system detects when the primary hydraulic control valve cannot maintain proper steering control and engages backup mechanisms to ensure continuous reliable control, preventing loss of control in low-flow situations.
Solution Approach 2:
The patent implements feedback control where the system continuously monitors hydraulic flow to the motors and adjusts control parameters accordingly. When flow levels indicate potential loss of control (such as in downhill situations), the feedback mechanism activates compensatory actions to maintain steering reliability, ensuring the system responds to changing conditions and prevents control loss.
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 system provides stable steering and speed control at high speeds, preventing uncontrolled movement by maintaining hydraulic fluid flow and allowing manual override, thus enhancing the tractor's stability and control across varying terrains.
Implementation Method 1
the first hydraulic pump including a first cam plate movable to vary the displacement of the pump to vary the volume of fluid generated as the pump is driven
Implementation Method 2
a hydraulic control valve arrangement responsive to the signals from the guidance controller for controlling flow in hydraulic fluid for supply of the fluid to first and second supply ducts
Implementation Method 3
a double acting hydraulic control cylinder arrangement for receiving the hydraulic fluid from the first and second supply ducts and including a drive shaft of the cylinder arrangement which is driven in first and second directions in response to supply of fluid from the first and second ducts
Data Source
AI summary
A tractor has hydraulically driven wheels at a cab end and castor wheels at an engine end. It can be driven cab forward in a working mode with a header on the forward end. It is rotated to engine forward in the transport position for more stable higher speed travel. The driven wheels are driven by hydraulic motors each having their own drive pump the output of which is controlled by a cam plate. There is provided an automatic steering system having a guidance controller arranged to receive GPS position information and feed back signals and to generate output for controlling a hydraulic control valve for controlling flow in hydraulic fluid for a double acting hydraulic control cylinder arranged to actuate pivotal movement of the steering link member independently of the steering shaft.