Working Vehicle Overload Prevention Control
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Solution Overview
Problem
Tractors experience engine stalls and excessive smoke when operating at low speeds in hard conditions due to insufficient engine output torque response, which can be exacerbated by reverse droop control leading to unintended increases in vehicle speed.
Innovation Solution
The implementation of an overload prevention control system that adjusts the engine driving point and continuously variable transmission gear ratio to maintain vehicle speed while increasing torque, using a combination of common rail fuel injection and hydraulic pump displacement control to manage engine load and prevent engine stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reverse droop control is employed to increase engine output torque at low speed, then engine reliability is improved, but vehicle speed becomes higher beyond expectation
Solution Approach 1:
The control device monitors vehicle speed and engine load continuously, and adjusts the engine driving point dynamically based on feedback from these parameters. When vehicle speed exceeds the target speed or engine load is insufficient, the control device reduces the engine rotating speed and torque, thereby preventing unintended speed increases while maintaining engine reliability.
Solution Approach 2:
The control device changes engine operating parameters (rotating speed and torque) dynamically by adjusting the engine driving point on the output characteristic map. This allows the system to adapt engine output to match actual workload requirements, preventing both engine stalls and unintended speed increases.
2Power
If engine rotating speed is increased to respond to rapid load increase, then engine output torque response is improved, but vehicle speed increases beyond expectation
Solution Approach 1:
The control device uses feedback from vehicle speed sensors and load sensors to determine when vehicle speed exceeds the target speed. It then adjusts the engine driving point to reduce rotating speed and torque output, ensuring that power increases do not translate to unintended speed increases.
Solution Approach 2:
The system dynamically adjusts the engine driving point based on real-time operating conditions. By making the engine control adaptive rather than fixed, the system can respond to rapid load changes while simultaneously controlling vehicle speed through coordinated adjustment of engine parameters.
3Reliability
If reverse droop control is used to prevent engine stalls, then engine reliability is improved, but fuel consumption increases
Solution Approach 1:
The control device adjusts engine operating parameters (rotating speed and torque) dynamically based on actual workload requirements. By optimizing the engine driving point to match actual demand rather than maintaining fixed high-output settings, the system prevents engine stalls while reducing unnecessary fuel consumption.
Data Source
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AI summary
In a working vehicle 141, there is dissolved a risk that a black smoke is discharged, a knocking is generated and an engine stall is caused, if a lot of load is applied to a rotary tiller 24 during various works while traveling at a low speed. In the working vehicle 141 provided with an engine 70 which is mounted to a travel machine body 142, a common rail type fuel injection device 117 which injects fuel to the engine 70, and a continuously variable transmission 159 which shifts power from the engine 70, an engine driving point Q (Q1 → Q2) relating to a rotating speed N and a torque T of the engine 70 is changed in such a manner that the rotation speed come to a high speed side rotating speed N2 dissolving an overload, and a change gear ratio of the continuously variable transmission 159 is modified and regulates in such a manner that a vehicle speed V of the travel machine body 142 does not change in the case that the overload acts on the engine 70 of having a low speed N1 in the rotating speed N.