Pilot Hydraulic Valve Switching for Precise Implement Positioning
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Solution Overview
Problem
Material moving machines, such as bulldozers, face challenges in efficiently controlling the position and movement of material moving implements due to limitations in hydraulic fluid handling systems, particularly in achieving precise control of extend and retract states at high translational velocities.
Innovation Solution
A pilot hydraulic switching system comprising a switching system control unit, first and second directional valves, and a variable position actuator valve, which shifts between static, extend, and retract states by controlling fluid flow to hold or change the positional state of the material moving implement, using pulse width modulation to achieve desired delta pilot pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional hydraulic fluid handling systems are used to control material moving implements, then the system structure is simple, but the control precision and response speed at high translational velocities are insufficient
Solution Approach 1:
The hydraulic control system is segmented into multiple directional valves (first directional valve, second directional valve) that independently control different aspects of implement positioning. Each valve handles specific control functions (extend/retract/hold states), allowing precise control at high velocities while maintaining manageable system complexity through functional decomposition
Solution Approach 2:
The system employs a variable position actuator valve that can dynamically shift between multiple positions (static state, retract state, extend state) based on real-time control signals. This dynamic adaptability enables the system to maintain precise control across varying translational velocities, resolving the contradiction between control precision and operational speed
2Speed
If conventional hydraulic switching systems are used, then the system is easy to operate, but the response time and speed control at high velocities are inadequate
Solution Approach 1:
The control system prepares hydraulic fluid pathways in advance through the directional valves, which can quickly switch between extend and retract configurations. This preliminary positioning of hydraulic flow paths enables rapid response when velocity changes are commanded, reducing response time loss at high translational velocities
Solution Approach 2:
The system uses periodic control signals to manage the directional valves and actuator valve, enabling rhythmic adjustment of hydraulic flow to maintain optimal response times during high-speed operation. This periodic control mechanism ensures consistent speed response without excessive response time delays
3Measurement precision
If a variable position actuator valve is introduced for precise control, then control precision improves, but the device complexity increases
Solution Approach 1:
The variable position actuator valve serves multiple functions simultaneously: it controls implement extension, retraction, and positioning, and can operate in different modes (opposing flow path mode, counter flow path mode, blocked flow path mode). This multi-functionality reduces the need for separate valves for each function, thereby limiting the increase in overall system complexity while maintaining high position control precision
Solution Approach 2:
The actuator valve acts as an intermediary between the control system and the hydraulic fluid handling system. It translates control signals into precise hydraulic actions, mediating between the simple control interface and the complex hydraulic requirements, thus achieving precise position control without proportionally increasing overall system complexity
4Reliability
If dual directional valves are used to control extend and retract states, then control reliability improves, but the device complexity increases
Solution Approach 1:
The first and second directional valves are merged into a coordinated control system that manages both extend and retract functions. By combining these valves with the variable position actuator valve into an integrated hydraulic control architecture, the system achieves enhanced reliability through redundant control pathways while limiting complexity increases through unified system design
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 precise control of material moving implements at high velocities, ensuring efficient displacement of materials and maintaining positional states, even under conditions of hydraulic or electrical failures, by balancing pressures and using pulse width modulation to achieve desired states within predetermined time frames.
Implementation Method 1
drive pressurized fluid in the extend pilot line and the retract pilot line simultaneously with a positive net pressure on the second control element of the variable position actuator valve and a negative net pressure on the first control element of the variable position actuator valve
Data Source
AI summary
In accordance with one embodiment of the present disclosure, a material moving machine comprises a pilot hydraulic switching system. The pilot hydraulic switching system comprises a control unit, a first directional valve, and a second directional valve. The control unit is configured to operate the first and second directional valves to shift a variable position actuator valve between a static state, a retract state, and an extend state. The actuator valve comprises a first and second control element. In the retract and extend states, the first and second directional valves control fluid flow to the variable position actuator valve with a positive net pressure on either the first or second control elements and a negative net pressure on the other control element to move the material moving implement. In the static state, the first and second directional valves control fluid flow equally on the first and second control elements.