Excavator Arm Stroke Control for Deep Digging Stability
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Solution Overview
Problem
The stability of working machines deteriorates when the boom and arm are stretched in the horizontal direction with a large excavation depth, and the low bucket height complicates efficient earth and sand movement.
Innovation Solution
A controller restricts the arm cylinder's stroke in the dumping direction when the arm's tip reaches a predetermined limit distance, ensuring stability by limiting the arm's movement and providing warnings or automatic control to maintain the arm's position relative to the boom's swing, using sensors to detect angles and calculate the arm's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the boom and arm are stretched in the horizontal direction to achieve large excavation depth, then the excavation depth is improved, but the stability of the machine body deteriorates
Solution Approach 1:
The patent implements dynamic control of the arm cylinder stroke based on real-time detection of boom angle and arm angle. The control unit dynamically adjusts the arm cylinder's stroke range according to the current configuration of the boom and arm, allowing maximum stroke when stability is not compromised and restricting stroke when the tip approaches the vertical line. This dynamic adjustment resolves the contradiction by enabling large excavation depth when safe and maintaining stability when needed.
Solution Approach 2:
The patent employs a feedback mechanism where detection units continuously monitor the boom angle and arm angle, and the control unit uses this feedback information to determine the appropriate stroke limit for the arm cylinder. The system calculates the position of the tip relative to the vertical line through feedback from angle sensors and adjusts the arm cylinder's operational range accordingly. This feedback loop allows the system to achieve large excavation depth while automatically maintaining machine body stability.
2Stability of the object's composition
If the arm cylinder stroke is restricted to maintain stability, then the machine body stability is improved, but the bucket height becomes low requiring additional arm dumping operations
Solution Approach 1:
The system dynamically adjusts the arm cylinder stroke restriction based on real-time detection of the tip's position relative to the vertical line. When the tip is far from the vertical line, the arm cylinder can operate with full stroke range, achieving large bucket height. When the tip approaches the vertical line, the stroke is restricted to maintain stability. This dynamic adjustment eliminates the need for additional arm dumping operations while maintaining stability, thus resolving the contradiction between stability and productivity.
3Stability of the object's composition
If the arm cylinder stroke is restricted when the tip is near the vertical line, then the machine body stability is improved, but the arm's movement freedom is reduced
Solution Approach 1:
The control system dynamically adjusts the arm cylinder's stroke range based on the real-time position of the tip relative to the vertical line. When the tip is far from the vertical line, the arm cylinder operates with full stroke freedom. When the tip approaches the vertical line, the stroke is restricted only in the direction that would compromise stability. This selective and dynamic restriction maintains arm movement freedom for most operations while ensuring stability when needed.
Solution Approach 2:
The patent applies stroke restriction locally and selectively - only when the tip is near the vertical line and only in the direction that would compromise stability. The arm cylinder retains full freedom of movement in all other conditions. This localized application of the constraint maintains arm versatility and adaptability for various excavation tasks while providing stability protection only when and where it is necessary.
Data Source
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AI summary
A working machine is desired to have stability in a case a boom (12) and an arm (13) are stretched in a horizontal direction with a bucket height and an excavation depth each set to be large. In the working machine, a stroke of an arm cylinder (20) caused when a distance of a tip portion of an arm (13) from a machine body (2) is equal to a predetermined limit distance (39) is defined as a stroke Y1, a stroke of a boom cylinder (19) caused when the stroke of the arm cylinder (20) is equal to the stroke Y1 and a height of the tip portion of the arm (13) is equal to a height of a boom pivot shaft (16) is defined as a stroke X1, and when the stroke of the boom cylinder (19) is between the stroke X1 and a stroke end thereof in a direction to swing the boom (12) upward, the controller (30) is configured or programmed to restrict the stroke of the arm cylinder (20) to swing the arm (13) in a dumping direction (D1) so as to prevent the arm (13) from swinging further in the dumping direction (D1) from a position where the stroke of the arm cylinder (20) is equal to the stroke Y1.