Hydraulic Control System for Automatic Implement Return
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Solution Overview
Problem
Existing hydraulic control systems for movable implements in working machines, such as loaders and forklifts, require operator intervention to return the implement to a preselected position or a free floating state, which can be cumbersome and distracting during repetitive tasks, especially when the operator needs to maneuver the vehicle to a new position.
Innovation Solution
A hydraulic control system that includes a pilot-operated valve, a manually operable joystick, an electrically operated valve, and an electrical circuit with sensors to automatically return the implement to a predetermined state or allow it to float independently of joystick operation, ensuring the implement returns to a preselected dig position or free floating state without continuous operator input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual operation is used to return the implement to a preselected position, then the operator has full control over the implement movement, but the operator becomes distracted and cannot focus on vehicle maneuvering
Solution Approach 1:
The system enables automatic return to dig (RTD) and return to float (RTF) functions where the implement automatically returns to predetermined positions without continuous operator intervention. The hydraulic control system detects implement position and autonomously controls the return movement, freeing the operator to focus on vehicle maneuvering while maintaining full control capability when needed.
2Extent of automation
If automatic return functions are implemented without pressure sensing, then the system responds faster, but accidental activation may occur causing safety issues
Solution Approach 1:
The system incorporates hydraulic pressure sensors that continuously monitor the pilot line pressure to detect the actual position of the implement. The automatic return functions are conditioned on pressure feedback - the system only activates RTD or RTF when the sensor confirms the implement is in the correct starting position, preventing accidental activation and ensuring safe operation.
3Productivity
If the implement returns to dig position automatically, then operational efficiency improves, but the system complexity increases due to additional sensors and control circuits
Solution Approach 1:
The system utilizes the existing hydraulic pilot line and pressure sensor infrastructure already present in the vehicle's hydraulic control system. By leveraging the pilot pressure signal that naturally exists during normal operation, the system adds RTD and RTF functionality without requiring separate complex positioning systems, thereby minimizing additional complexity while achieving automatic return 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 safe and automatic return to dig or float positions, allowing the operator to focus on vehicle maneuvering, reducing the risk of accidents and improving operational efficiency by requiring joystick movement and switch activation for initiating these functions.
Implementation Method 1
a hydraulic pressure sensor connected to a pilot line
Implementation Method 2
a pilot-operated valve for selectively connecting the high pressure supply line and the return line to the hydraulic actuator, the valve having a spool movable by the action of the hydraulic pilot pressure
Implementation Method 3
an electrically operated valve for bypassing the pilot valve and supplying hydraulic pilot pressure to the pilot-operated valve independently of the position of the joystick
Data Source
AI summary
A working machine including a movable implement, a hydraulic actuator for displacing the implement, and a hydraulic control system for enabling an operator to control movement of the implement. The control system allows the implement to be returned to a desired position or state, such as a return to dig position or a return to float state, in a single automated operation that is initiated by the operator actuating a switch at the same time as moving a joystick in a desired direction. A pilot-operated valve is used to supply hydraulic fluid under pressure to the actuator acting on the implement and the operation of the joystick is detected by means of a pressure sensor connected to a control line of the pilot-operated valve.