Engine Rotation Control for Electric Dump Trucks
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Solution Overview
Problem
Existing engine rotation control systems for electrically driven dump trucks result in fuel wastage and increased noise due to maintaining medium rotational speed even when not needed, causing response lag and affecting acceleration when starting from standstill and during deceleration or coasting.
Innovation Solution
An engine rotation control system that dynamically adjusts engine speed based on vehicle status, using a controller to set optimal rotational speed according to drive mode, reducing engine speed when not necessary, and implementing torque control for improved responsiveness and acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine is maintained at medium rotational speed when the shift lever is in F or R position, then good responsiveness and acceleration are obtained when the truck starts moving or when the driver depresses the accelerator pedal, but fuel is wasted and noise is increased when the truck is coasting, decelerating, or standing still
Solution Approach 1:
The engine control system dynamically adjusts the engine's rotational speed based on real-time vehicle operating conditions. When the vehicle is coasting, decelerating, or standing still, the engine speed is reduced to minimum rotational speed to save fuel. When the vehicle needs to accelerate or start moving, the engine speed is increased to medium rotational speed for better responsiveness. This dynamic adjustment resolves the contradiction between maintaining good response and reducing fuel consumption.
Solution Approach 2:
The system changes the engine's operational parameter (rotational speed) according to different driving conditions. By switching between minimum rotational speed and medium rotational speed based on vehicle status, the system optimizes both fuel efficiency and performance, resolving the contradiction between energy saving and responsive acceleration.
2Use of energy by moving object
If the engine speed is set to minimum rotational speed when the depressed amount of the accelerator pedal is in the range of 0 to a predetermined small amount, then fuel consumption is reduced and noise is minimized, but torque control is performed on the electric motor after the engine speed has increased from minimum to medium rotational speed, causing response lag
Solution Approach 1:
The control system performs preliminary action by pre-increasing the engine speed to medium rotational speed when the vehicle is in a state where acceleration is anticipated (shift lever in F or R position, vehicle stopped or moving at low speed). This preliminary speed increase ensures that when the driver depresses the accelerator pedal, the engine is already at the optimal speed for immediate torque delivery, eliminating response lag while maintaining fuel efficiency during coasting or idle periods.
3Productivity
If the engine speed is maintained at medium rotational speed during vehicle operation, then acceleration performance is improved, but the engine life is reduced due to continuous operation at higher speeds
Solution Approach 1:
The system dynamically adjusts engine speed based on actual driving needs rather than maintaining a constant medium rotational speed. During coasting, deceleration, or idle periods, the engine operates at minimum rotational speed, reducing wear and extending engine life. During acceleration or when the driver depresses the accelerator pedal, the engine speed increases to medium rotational speed to provide necessary acceleration performance. This dynamic operation pattern resolves the contradiction between acceleration performance and engine longevity.
Data Source
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AI summary
A vehicle status judging unit determines whether the following conditions are met: the shift position of a shift lever 4 is the F or R position (condition 1); brakes (5, 6, 8) are inactive (condition 2); the vehicle stands still (condition 3); the depressed amount of an accelerator pedal 9 is equal to or less than δ (condition 4); and the rotational speed of an engine 1 is equal to or less than a medium rotational speed (condition 5). An engine rotation control unit controls the engine 1 such that the rotational speed of the engine 1 become equal to a minimum rotational speed if conditions 1, 2, and 4 are met and condition 3 is not met or if condition 1 is met and condition 2 is not met. The engine rotation control unit also controls the engine 1 such that the rotational speed of the engine 1 becomes equal to the medium rotational speed if conditions 1, 2, 3, and 5 are met or if conditions 1, 2, and 5 are met and conditions 3 and 4 are not met.