Wheel Loader Traction Control on Slippery Surfaces
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Solution Overview
Problem
Wheel loaders experience slippage on slippery road surfaces due to low traction force, leading to reduced working efficiency when excavating and loading materials.
Innovation Solution
A loading work vehicle equipped with a traveling state detection sensor, operation detection sensor, mode switch device, and controller that adjusts the maximum traction force based on the static friction coefficient and vehicle weight, allowing for dynamic control between limit and normal modes to optimize traction force during excavation and travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the maximum traction force is increased to prevent wheel slippage on slippery surfaces, then the working efficiency is improved, but the digging force balance is disrupted and the lift arm cannot be lifted properly
Solution Approach 1:
The patent applies dynamics by making the traction force control system adaptive and variable rather than fixed. The controller dynamically adjusts the traction force based on real-time detection of work device operation state, switching between a first maximum traction force during travel and a second maximum traction force during excavation. This dynamic adjustment resolves the contradiction by allowing high traction force during travel to prevent slippage while limiting traction force during excavation to maintain digging force balance.
Solution Approach 2:
The patent changes the parameter of maximum traction force based on operational conditions. By detecting whether the work device is performing excavation or travel operations, the system switches between two distinct traction force parameter settings. This parameter change enables the system to optimize traction force for each specific operation type, preventing wheel slippage during travel while maintaining proper digging force balance during excavation.
2Ease of operation
If the traction force is limited to maintain digging force balance, then the lifting operation is facilitated, but wheel slippage occurs on slippery road surfaces
Solution Approach 1:
The system uses dynamic control to adjust traction force based on the current operational phase. During travel on slippery surfaces, the controller allows higher traction force to maintain wheel grip and prevent slippage. When excavation operations begin, the controller dynamically reduces the maximum traction force to maintain digging force balance and facilitate lift arm operation. This dynamic adaptation resolves the contradiction between wheel traction reliability and lifting operation ease.
Solution Approach 2:
The patent implements feedback control by using operation detection sensors to monitor the work device state and feeding this information back to the controller. The controller continuously adjusts the traction force based on this feedback, switching between different maximum traction force levels according to whether the system is in travel or excavation mode. This feedback mechanism ensures reliable wheel traction during travel while enabling easy lifting operations during excavation.
3Ease of operation
If the HST motor tilt is limited to 50%-70% of maximum, then the traction force is suppressed for lifting operations, but the traction force is insufficient for pushing the bucket into natural ground on slippery surfaces
Solution Approach 1:
The patent changes the HST motor tilt parameter based on operational conditions. Instead of using a fixed tilt limitation of 50%-70%, the system switches between two tilt parameter settings: a first tilt angle range that limits traction force during excavation to facilitate lifting operations, and a second tilt angle range that allows higher traction force during travel on slippery surfaces to push the bucket into natural ground. This parameter change resolves the contradiction between lifting operation ease and sufficient traction force.
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
Improves working efficiency on slippery surfaces by maintaining sufficient traction force during excavation and travel, reducing slippage and operator fatigue.
Implementation Method 1
a variable displacement type traveling hydraulic pump driven by the engine; a variable displacement type traveling hydraulic motor that is connected to the traveling hydraulic pump by a closed circuit and transmits drive force of the engine to the wheels
Implementation Method 2
a static friction coefficient between the wheels and the road surface is small, the wheels of the wheel loader slip
Data Source
AI summary
Provided is a loading work vehicle capable of improving work efficiency even when working on a slippery road surface. An HST-traveling-drive wheel loader 1 comprises a step-on amount detection sensor 610, a discharge pressure detection sensor 75, a mode switch device 60, and a controller 5. The controller 5 is configured to: determine whether a limit mode is selected by the mode switch device 60; specify an operation state of the wheel loader 1 when determining that the limit mode is selected; limit maximum traction force to a first set value which is set based on a static friction coefficient μ and vehicle weight when specifying that a bucket 23 is pushed into a natural ground 100; and increase the maximum traction force from the first set value when specifying that excavation of the natural ground 100 is started.