Lift Arm Suspension Controller for Uncommanded Lowering Prevention
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Solution Overview
Problem
Power machines without suspension systems between the frame and axles experience uncommanded lowering of lift arm assemblies due to insufficient accumulator charge, leading to an uncontrolled downward force on the lift arm, causing an uncommanded lowering when traversing rough terrain.
Innovation Solution
A selectively activated lift arm suspension system with a controller that deactivates the system when the lift arm assembly moves beyond a predetermined threshold, preventing uncommanded lowering by comparing the measured position to a stored position and adjusting the hydraulic fluid flow accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lift arm suspension system is activated to allow movement for absorbing shock, then ride comfort is improved, but uncommanded lowering occurs when the accumulator is not sufficiently charged
Solution Approach 1:
The controller continuously monitors the position of the lift arm assembly and compares it to a stored reference position. When the position difference exceeds a predetermined threshold, the controller automatically deactivates the suspension system, preventing uncommanded lowering while maintaining ride comfort during normal operation.
Solution Approach 2:
The suspension system is designed to be selectively activatable and deactivatable based on operating conditions. The system dynamically transitions between active and inactive states based on real-time position monitoring, allowing optimal performance across different terrain conditions and accumulator charge levels.
2Force
If the lift arm assembly is allowed to move up and down to absorb shock, then shock absorption is improved, but hydraulic fluid is diverted to the accumulator causing uncommanded lowering
Solution Approach 1:
The controller monitors lift arm position and uses this feedback to determine when to deactivate the suspension system. When excessive movement is detected that would cause harmful hydraulic fluid diversion, the system automatically deactivates, preventing both the uncommanded lowering and potential damage from excessive fluid transfer.
Solution Approach 2:
The system takes preliminary action by deactivating the suspension system before harmful hydraulic fluid diversion can occur. The controller anticipates potential problems by continuously monitoring position and preemptively deactivating when threshold violations are detected, preventing the uncommanded lowering before it fully develops.
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 solution effectively prevents uncommanded lowering of the lift arm assembly, providing controlled ride stability and preventing hydraulic fluid diversion to the accumulator, thus maintaining operational stability and safety on rough terrain.
Implementation Method 1
a hydraulic system including one or more hydraulic pumps that provide pressurized hydraulic fluid to accomplish a number of tasks
Implementation Method 2
positioning a lift arm assembly... providing hydraulic fluid to actuators on certain implements
Implementation Method 3
Typical lift arm suspension systems utilize an accumulator to store pressurized hydraulic fluid that aids one or more lift actuators to raise or lower the lift arm assembly slightly
Implementation Method 4
a lift arm assembly pivotally coupled to the frame that is capable of being raised and lowered with respect to the frame
Data Source
AI summary
Disclosed are power machines and lift arm suspension or ride control systems for use thereon. A lift arm assembly is pivotally coupled to a frame of the power machine and is capable of being raised and lowered. A selectively activated lift arm suspension system is operably coupled to the lift arm assembly. A controller is coupled to the suspension system and configured to determine whether the lift arm assembly has moved more than a threshold amount. The controller deactivates the lift arm suspension system in response to determining that the lift arm assembly has moved more than the threshold amount.