Rear Steering Hydraulic System for Independent Caster Wheel Control
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Solution Overview
Problem
Agricultural machines with dual-path hydrostatic systems face challenges in independently controlling steerable rear caster wheels, particularly when reversing or encountering significant lateral forces, which affects their steerability and versatility.
Innovation Solution
A hydraulic system comprising a pressure source, tank, actuators, and a valve block with specific fluid circuits and valves allows for independent control of rear caster wheels, enabling passive or active steering through a rear steering control valve that can switch between states to manage fluid communication and provide proportional control, along with a cross-port pressure relief system for independent wheel rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the rear caster wheels are controlled to rotate independently using a hydraulic system, then steerability and versatility are improved, but the device complexity increases due to additional valves and fluid circuits
Solution Approach 1:
The patent combines multiple hydraulic control functions into a single integrated valve block that houses the rear steering control valve, left steering command valve, and right steering command valve. This merging of components reduces overall system complexity while maintaining the capability for independent rear wheel steering control.
Solution Approach 2:
The rear steering control valve serves multiple functions: it controls fluid communication between the supply pressure circuit and command valves for active steering, connects the tie rod circuit for passive steering, and manages return flow to the tank. This multi-functionality reduces the need for separate dedicated components.
2Adaptability or versatility
If the rear steering control valve switches between states to enable independent wheel rotation, then versatility is improved, but the ease of operation decreases due to complex fluid circuit management
Solution Approach 1:
The hydraulic system is designed to automatically transition between active and passive steering modes through the rear steering control valve's automatic response to operational conditions. The valve self-regulates fluid communication based on system state, reducing the need for manual intervention or complex operator decisions.
Solution Approach 2:
The rear steering control valve dynamically switches between different fluid circuit configurations based on operational requirements. The valve can transition between connecting the supply pressure circuit to command valves (active steering mode) and connecting the tie rod circuit (passive steering mode), allowing the system to adapt its control mechanism in real-time.
3Adaptability or versatility
If the hydraulic system provides both active and passive control modes, then adaptability is improved, but the device complexity increases due to multiple fluid circuits and valves
Solution Approach 1:
Multiple fluid circuits (supply pressure, command valve supply, tie rod, and tank return circuits) are merged and integrated through a single valve block that contains all necessary control valves. This consolidation reduces the physical separation of components and simplifies the overall system architecture while maintaining multiple control modes.
Solution Approach 2:
The valve block serves as a universal control unit that manages all fluid circuit connections for both active and passive steering modes. The rear steering control valve and command valves work together as an integrated team to provide both control modes through a single multi-functional component assembly.
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 hydraulic system enables smooth and responsive control of rear caster wheels, allowing them to rotate independently, enhancing steerability and versatility, especially during reversing and when encountering obstacles like rocks.
Implementation Method 1
A pressure source is provided and configured to supply a flow of pressurized fluid
Implementation Method 2
the vehicle may be equipped with a hydraulic system that actuates hydraulic cylinders to control the position of the rear caster wheels
Data Source
AI summary
A hydraulic system for controlling a pair of steerable caster wheels includes a left steering command valve, a right steering command valve, and a rear steering control valve. A supply pressure fluid circuit interconnects a pressure source and the rear steering control valve. A command valve supply fluid circuit interconnects the rear steering control valve with both the right steering command valve and the left steering command valve. A left side steering fluid circuit interconnects a left side actuator and the left steering command valve. A right side steering fluid circuit interconnects a right side actuator and the right steering command valve. A fluidic tie rod fluid circuit interconnects both the left side actuator and the right side actuator with the rear steering control valve. A tank return fluid circuit interconnects the rear steering control valve, the left and right steering command valves, and a tank.