Relief-Valve Slope Control for Four-Legged Construction Machines
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Solution Overview
Problem
Construction machines like cold planers and rotary mixers face instability issues due to uneven terrain, which affects the movement and cutting depth of their propulsors, leading to potential instability and reduced operational efficiency.
Innovation Solution
A slope control system using a hydraulic system with relief valves to individually control the rear lifting columns of the machine, allowing for independent movement and maintaining the center of gravity within a stable operating envelope, thereby enhancing stability and operational flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a hydraulic system with relief valves is used to individually control rear lifting columns, then stability and operational envelope are improved, but device complexity increases
Solution Approach 1:
The hydraulic system is segmented into separate circuits for left and right rear lifting columns, with independent relief valves (128A, 128B) controlling each column individually. This segmentation allows independent height adjustment of each lifting column, enabling the machine to adapt to uneven terrain and maintain stability without requiring a completely complex centralized control system.
Solution Approach 2:
Relief valves (128A, 128B) are introduced as intermediary components between the hydraulic pump and the lifting columns. These valves act as mediators that automatically regulate hydraulic fluid flow and pressure to each lifting column, simplifying the control mechanism while maintaining system stability and preventing uncontrolled movement.
2Adaptability or versatility
If independent control of rear lifting columns is implemented, then operational flexibility is enhanced, but ease of operation decreases
Solution Approach 1:
The relief valves (128A, 128B) are configured to automatically regulate hydraulic fluid flow to the lifting columns based on system pressure conditions without requiring manual intervention. The system serves itself by using the hydraulic pressure generated during normal operation to control the lifting column heights, eliminating the need for complex manual control mechanisms and maintaining ease of operation while achieving adaptability.
3Stability of the object's composition
If relief valves are used to control fluid flow between lifting columns, then stability on uneven terrain is improved, but loss of energy increases
Solution Approach 1:
The relief valves (128A, 128B) convert the potentially harmful effect of hydraulic pressure fluctuations and energy loss into a beneficial control mechanism. By allowing controlled fluid flow between lifting columns through these valves, the system uses the inherent hydraulic pressure to automatically balance the machine on uneven terrain, transforming energy that would otherwise be lost into a stabilizing force that equalizes column heights and maintains operational stability.
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 improves the stability and operational envelope of construction machines by allowing independent control of rear lifting columns, preventing tilting and maintaining a stable cutting depth, even on uneven terrain, thus enhancing safety and operational efficiency.
Implementation Method 1
a hydraulic system controls a height of each of the plurality of vertically moveable legs
Implementation Method 2
a first relief valve to control flow of fluid from the first leg to the second leg in a first direction, and a second relief valve to control flow of fluid from the second leg to the first leg in a second direction
Data Source
AI summary
A machine comprises a frame, a plurality of ground engaging units, a plurality of moveable legs, and a hydraulic system. A first ground engaging unit and a second ground engaging unit connect a first leg and a second leg, respectively, with the frame. The hydraulic system controls heights of the plurality of moveable legs. The hydraulic system comprises a fluid circuit to control fluid between the first and second legs, a load holding valve to control fluid flow into the fluid circuit, and first and second relief valves to control flow of fluid between the first and second legs in opposite directions. A method for controlling slope of a construction machine comprises activating a relief valve connecting right and left lifting cylinders to control flow of hydraulic fluid between the lifting cylinders to control retraction of one of the lifting cylinders from retracting.