Wheel Loader Excavation Mode Switching for Traction Balance
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Solution Overview
Problem
Existing wheel loaders struggle to balance traction force and digging force during excavation, leading to overloading or difficulty in scooping up work objects, particularly for inexperienced operators.
Innovation Solution
A wheel loader with a semi-automatic excavation mode that includes a controller to automatically adjust engine speed and transmission gear stage based on the specific gravity and moisture content of the work object, switching between heavy and light excavation modes to optimize traction and digging forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the traction force is increased during excavation, then the vehicle body can move forward more effectively, but the bucket may be pushed into the work object excessively causing overloading
Solution Approach 1:
The control device dynamically adjusts the engine speed parameter based on the relationship between traction force and digging force. When the traction force exceeds the digging force, the controller reduces engine speed to decrease both traction force and hydraulic pump output, preventing overloading. This parameter change approach resolves the contradiction by making the system adaptive to real-time force balance conditions.
2Object-affected harmful factors
If the traction force is decreased during excavation, then overloading is prevented, but the vehicle body cannot move forward effectively making it difficult to push the bucket into the work object
Solution Approach 1:
The controller monitors the force balance between traction and digging operations in real-time. When the traction force becomes insufficient to push the bucket into the work object, the controller increases engine speed to restore adequate traction force. This dynamic parameter adjustment ensures the system maintains optimal force balance, preventing both overloading and insufficient pushing force.
3Power
If the engine speed is not limited during excavation, then maximum power is available for both travel and cargo handling, but the balance between traction force and digging force cannot be controlled
Solution Approach 1:
The control device implements self-service by automatically monitoring the force balance between traction and digging operations and adjusting engine speed without operator intervention. The controller calculates whether traction force exceeds or falls short of digging force based on hydraulic pump discharge pressure and cargo handling device operation state, then autonomously modifies engine speed to maintain optimal balance. This eliminates the need for operator skill in force balance control while preserving maximum power availability when appropriate.
Data Source
Figure 1
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Figure 3
AI summary
In the wheel loader 1 equipped with a semi-automatic excavation mode function in which the controllers 5, 5A, 5B automatically control the travel drive device 3 and the cargo handling device 2 to assist the operator's operation, the semi-automatic excavation mode includes a first excavation mode in which the controllers 5, 5A, 5B do not limit the engine speed of the engine 30, and a second excavation mode in which the controllers 5, 5A, 5B limit the engine speed of the engine 30 so that the traction force by the travel drive device 3 is smaller than in the first excavation mode. In addition, the controllers 5, 5A, 5B switch between the first excavation mode and the second excavation mode based on the discharge pressure Pa of the hydraulic pump 33 immediately before the start of the excavation operation or the first to third mode selection switches 61 to 63.