Engine Control Device Speed Limiting for Wheel Loader Workability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During excavation work with a wheel loader, excessive travel driving force can reduce the lifting force of the lift arm, impairing workability due to increased reaction forces when the bucket is dug into a mound.
Innovation Solution
An engine control device that includes a rotation speed control unit, hydraulic pump, and travel drive device with detection units for accelerator pedal operation, torque converter speed ratio, load pressure, and transmission speed stage, which limits the engine's maximum speed when specific conditions are met, reducing travel driving force and improving workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the maximum engine speed is limited to improve workability, then the lifting force is improved, but the travel driving force is reduced
Solution Approach 1:
The system dynamically adjusts the maximum engine speed limit based on the transmission speed stage detection. The ECU raises or lowers the speed limit according to whether the transmission is in high, intermediate, or low speed stage, allowing optimal power distribution between travel and lifting functions depending on current operational needs.
Solution Approach 2:
The system performs preliminary detection of the transmission speed stage and pre-adjusts the maximum engine speed limit accordingly. By detecting the speed stage in advance and setting appropriate speed limits before the lifting or traveling operation, the system proactively optimizes performance rather than reacting after the contradiction arises.
2Power
If the engine speed is increased to provide greater power, then the power output is improved, but the reaction force on the lift arm increases, reducing workability
Solution Approach 1:
The patent changes the engine speed parameter based on transmission speed stage detection. By linking the maximum speed limit to the transmission ratio, the system automatically adjusts power output characteristics to match the mechanical advantage available at each speed stage, resolving the contradiction between power output and workability.
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 engine control device effectively reduces travel driving force and enhances workability by limiting engine speed when predetermined conditions are satisfied, allowing easier lifting of the bucket and improving excavation efficiency.
Implementation Method 1
a travel drive device that transmits a rotation of the engine to wheels through a torque converter
Data Source
Figure 1
Figure 2
Figure 3
AI summary
There are provided: a pedal operation amount detection unit 12 that detects an operation amount s of the accelerator pedal 11; a speed ratio detection unit 14, 15 that detects a speed ratio e of an input shaft and an output shaft of the torque converter 2; a load pressure detection unit 16 that detects a load pressure P of the hydraulic pump 6; a speed stage detection unit 18 that detects a low speed stage of a transmission 3 capable of varying a speed stage between a low speed stage and a high speed stage; and a speed limiting unit 10 that limits a maximum speed of the engine 1 to a lower speed upon satisfaction of following speed limitation conditions: at least a pedal operation amount s is equal to or greater than a predetermined value s1, a speed ratio e is equal to or less than a predetermined value ea, a load pressure P is equal to or greater than a predetermined value Pa, and the low speed stage of the transmission has been detected.