Wheel Loader Tractive Force Control for Excavating Work
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Solution Overview
Problem
Wheel loaders face challenges in optimizing tractive force during excavating work, leading to excessive bucket penetration in lightweight or loose objects and potential wheel slippage on slippery grounds, resulting in reduced workability and increased fuel consumption.
Innovation Solution
A wheel loader system with a level selecting unit and control unit that allows operators to choose from multiple tractive force levels based on object type and ground conditions, adjusting engine throttle and torque output to optimize force application, including a mode selecting unit for high-output and low-output modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the tractive force is increased to improve the ability to raise the work implement, then the lifting capability is improved, but the bucket penetration depth becomes excessive and wheel slippage occurs
Solution Approach 1:
The patent applies dynamics by making the tractive force characteristic adjustable and movable rather than fixed. The control unit dynamically switches between first and second tractive force characteristics based on operating conditions (velocity stage and level selection), allowing the tractive force to adapt to different work scenarios. This resolves the contradiction by enabling the system to provide high tractive force when needed (to raise the implement) while preventing excessive penetration through the second characteristic with reduced force.
2Manufacturing precision
If the tractive force is reduced to control bucket penetration depth, then the penetration control is improved, but the ability to raise the work implement is insufficient
Solution Approach 1:
The system resolves this contradiction by providing two dynamic tractive force characteristics that can be switched based on needs. The first characteristic maintains higher tractive force for lifting capability, while the second characteristic reduces tractive force for penetration control. The operator can select the appropriate characteristic through the level selecting unit, ensuring both lifting capability and penetration control are available when needed.
3Reliability
If the tractive force is increased to prevent wheel slippage on slippery ground, then the traction reliability is improved, but the energy consumption increases
Solution Approach 1:
The patent applies parameter changes by modifying the tractive force characteristic parameter based on operating conditions. The control unit changes the tractive force parameter between two distinct characteristics depending on the velocity stage and level selection. This allows the system to use higher force parameters when traction reliability is critical (preventing wheel slippage) while using lower force parameters during normal operation to reduce fuel consumption.
4Use of energy by moving object
If the tractive force is reduced to decrease fuel consumption, then the energy efficiency is improved, but the workability deteriorates due to insufficient lifting force
Solution Approach 1:
The system resolves this contradiction through dynamic adjustment of tractive force characteristics. The control unit can switch between the first characteristic (higher force for workability) and the second characteristic (lower force for fuel efficiency) based on the velocity stage and operator selection. This ensures that when workability is critical (needing to raise the implement), the system provides sufficient force, while during steady-state operation, fuel consumption is reduced.
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 effectively reduces excessive bucket penetration and wheel slippage, enhancing workability and reducing fuel consumption by allowing precise control of tractive force levels during excavating operations.
Implementation Method 1
The travel drive device has a torque converter and a transmission.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A level selecting unit is a device for selecting a tractive force level from a plurality of levels when a velocity stage of a transmission is a first velocity. The plurality of levels includes at least a first level and a second level. A control unit controls the engine. When the velocity stage of the transmission is the first velocity and the first level is selected, the control unit controls the engine on the basis of a first tractive force characteristic. The first tractive force characteristic prescribes a relationship between the vehicle speed and the tractive force of the vehicle. When the velocity stage of the transmission is the first velocity and the second level is selected, the control unit controls the engine on the basis of a second tractive force characteristic. The tractive force is reduced more in the second tractive force characteristic than in the first tractive force characteristic.