Work Vehicle Engine Torque Control for Low Reducing Agent
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Solution Overview
Problem
Operators of work vehicles may not adequately sense a reduction in engine horsepower when the reducing agent level is low, especially in low-load working modes, leading to insufficient maintenance and potential emissions of unfiltered nitrogen oxides.
Innovation Solution
A work vehicle system that includes an engine, an exhaust gas purification apparatus, a reducing agent tank, a state determination portion, and an engine control unit, which uses a restricted-operation engine output torque curve to lower horsepower output when the reducing agent level falls below a reference value, ensuring the operator perceives the reduction regardless of the working mode, and adjusts hydraulic pump absorption torque accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the engine is controlled to low output when reducing agent level is low, then nitrogen oxide emissions are reduced, but the operator may not sufficiently sense the low output in low-load working modes
Solution Approach 1:
The patent applies dynamics by making the engine output characteristics changeable based on operating conditions. The engine control unit dynamically adjusts the output characteristics to ensure operator awareness: in low-load working modes, the engine maintains higher output to be noticeable, while in high-load modes, it restricts output more severely. This dynamic adjustment resolves the contradiction between reducing emissions and ensuring operator awareness.
Solution Approach 2:
The patent changes the engine output torque curve as a parameter based on the detected working mode and reducing agent level. When reducing agent is low, the system selects different torque curves depending on the working mode: a first torque curve for low-load modes that maintains noticeable output, and a second torque curve for high-load modes that severely restricts output. This parameter change strategy ensures both emission reduction and operator awareness.
2Object-affected harmful factors
If the engine output is restricted using a standard low-output control, then emissions are controlled, but working efficiency is reduced in high-load modes
Solution Approach 1:
The system dynamically adapts engine output restriction to the actual working mode. In high-load working modes, the engine control unit applies severe output restriction when reducing agent is low, which is appropriate for emission control during heavy operations. In low-load modes, the system maintains higher output to preserve working efficiency for light operations. This dynamic adaptation resolves the contradiction between emission control and working efficiency.
Solution Approach 2:
The patent changes the engine torque curve parameter based on the combination of reducing agent level and working mode. Two distinct torque curves are defined: a first torque curve for low-load modes that maintains acceptable working efficiency, and a second torque curve for high-load modes that prioritizes emission control. The control unit selects the appropriate torque curve based on real-time conditions, resolving the efficiency-emission contradiction.
3Ease of operation
If the engine control is adjusted to maintain operator awareness, then operator awareness of low reducing agent level is improved, but nitrogen oxide emissions may increase
Solution Approach 1:
The patent applies local quality by making the engine output characteristics different for different working modes. Instead of a uniform output restriction, the system provides localized output characteristics: higher output in low-load modes for operator awareness, and lower output in high-load modes for emission control. This localized differentiation resolves the contradiction between operator awareness and emission reduction.
Solution Approach 2:
The system changes the engine torque curve parameter based on working mode detection. When a low-load working mode is detected, the system selects a torque curve that maintains higher output for operator awareness. When a high-load mode is detected, it selects a torque curve with lower output for emission control. This conditional parameter change resolves the contradiction between awareness and emissions.
4Productivity
If multiple torque curves are used based on working mode, then working efficiency is optimized for different load states, but system complexity increases
Solution Approach 1:
The patent segments the engine torque characteristics into multiple discrete torque curves, each optimized for specific working modes. The control system detects the current working mode and selects the appropriate pre-defined torque curve. This segmentation approach optimizes working efficiency for different load states while keeping the control logic relatively simple through curve selection rather than continuous calculation.
Solution Approach 2:
The system performs preliminary action by pre-defining multiple torque curves corresponding to different working modes before operation. During operation, the control unit simply detects the working mode and selects the appropriate pre-prepared torque curve, avoiding complex real-time calculations. This preliminary preparation optimizes efficiency while minimizing control system complexity.
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
Ensures operators are alerted to low reducing agent levels, prompting maintenance and reducing nitrogen oxide emissions by consistently lowering engine output and hydraulic pump torque when the agent level is low, regardless of the working mode.
Implementation Method 1
An exhaust treatment apparatus reduces a nitrogen oxide (NOx) contained in a gas exhausted from an engine (an exhaust gas), to a harmless gas through NOx reduction reaction
Implementation Method 2
The reducing agent stored in the reducing agent tank is injected into the exhaust gas... reduces a nitrogen oxide (NOx) contained in a gas exhausted from an engine through NOx reduction reaction
Data Source
AI summary
A work vehicle having a plurality of working modes allowing working in accordance with a load state includes an engine, an exhaust gas purification apparatus, a reducing agent tank, a state determination portion, and an engine control unit. The exhaust gas purification apparatus purifies a nitrogen oxide in an exhaust gas. The reducing agent tank stores a reducing agent. The state determination portion determines a state of the reducing agent. The engine control unit controls output of the engine with the use of a restricted-operation engine output torque curve in which horsepower output from the engine is lower than horsepower output from the engine at the time when each of the plurality of working modes is selected, when a state of the reducing agent is equal to or lower than a reference value.