Hydraulic Working Machine Emission Control via Assist Motor
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Solution Overview
Problem
Hydraulic working machines like hydraulic shovels face challenges in minimizing emissions of particulate matter (PM) and nitrogen oxides (NOx) due to extreme fluctuations in engine load, leading to increased costs and reduced reliability, as existing control methods do not effectively associate target engine speed and torque with emission reduction regions.
Innovation Solution
A hybrid-driven hydraulic working machine with an assist electric motor, engine, and hydraulic pump, featuring a storage device for setting a specific engine revolution speed to minimize pollutant emissions, an engine revolution speed control device, and an electric motor control device that computes differential torque for power running and generation control, allowing the assist electric motor to compensate for load fluctuations and maintain target output torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If exhaust gas after-treatment devices (DPF, urea SCR system) are installed to reduce PM and NOx emissions, then emissions are reduced, but system cost and complexity increase significantly
Solution Approach 1:
The invention extracts the emission control function from the exhaust gas after-treatment system and relocates it to the engine combustion control system. By controlling combustion parameters (injection timing, injection amount, air intake amount) to maintain specific combustion temperature and pressure, the system achieves emission reduction without requiring complex after-treatment devices like DPF or urea SCR systems.
Solution Approach 2:
The invention replaces the mechanical/chemical after-treatment system with an electronic control system that manages combustion parameters. The control unit adjusts injection timing, injection amount, and air intake based on operating conditions to maintain optimal combustion characteristics, substituting complex physical after-treatment hardware with electronic sensorimotor control.
2Object-generated harmful factors
If exhaust gas after-treatment devices are installed to reduce PM and NOx emissions, then emissions are reduced, but installation cost increases
Solution Approach 1:
The invention extracts the emission control function from expensive after-treatment hardware and implements it through software-based combustion parameter control. By managing injection timing, injection amount, and air intake to maintain specific combustion conditions, the system eliminates the need for costly platinum catalysts, urea storage tanks, and complex after-treatment infrastructure.
Solution Approach 2:
The invention uses inexpensive, easily replaceable sensors and electronic control components instead of expensive, durable after-treatment hardware. The electronic control system with sensors for detecting combustion parameters and a control unit for adjusting injection and air intake is far less costly than installing and maintaining DPF filters, urea SCR systems, and platinum catalysts.
3Productivity
If engine load fluctuates extremely (0 to 100 percent rated torque) to meet hydraulic working demands, then machine productivity is maintained, but emissions control becomes unstable
Solution Approach 1:
The invention implements dynamic combustion control that continuously adjusts injection timing, injection amount, and air intake based on real-time operating conditions. The control unit monitors combustion parameters and dynamically modifies combustion characteristics to maintain stable emission levels even as engine load fluctuates between 0 and 100 percent rated torque during hydraulic operations.
Solution Approach 2:
The invention employs a feedback control system with sensors that detect combustion parameters (temperature, pressure, injection timing) and feed this information to the control unit. The control unit processes this feedback and adjusts injection timing, injection amount, and air intake to maintain optimal combustion characteristics and stable emissions control across all operating conditions.
4Use of energy by moving object
If engine capacity is reduced to lower cost and improve fuel efficiency, then fuel consumption decreases, but ability to handle sudden hydraulic load increases is compromised
Solution Approach 1:
The invention changes the parameters of combustion (timing, amount, air intake) rather than changing engine physical capacity. By optimizing these parameters to maintain specific combustion temperature and pressure, the system enables smaller engines to deliver equivalent effective power output while improving fuel efficiency. The control system compensates for reduced engine capacity through precise combustion management.
Solution Approach 2:
The invention applies preliminary control actions by pre-calculating and pre-adjusting injection timing, injection amount, and air intake based on anticipated hydraulic load requirements. The control unit receives operation signals and proactively adjusts combustion parameters before load fluctuations occur, preventing power deficiency and maintaining stable operation with smaller engine capacity.
Data Source
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AI summary
A hydraulic working machine is provided which has an assist electric motor connected to an engine and a hydraulic pump, the hydraulic working machine being structured in such a manner that the emissions of air pollutants in the exhaust gas from the engine are minimized regardless of fluctuations in the load torque of the hydraulic pump, that the increasing cost of installing an exhaust gas after-treatment device is lowered, and that the reliability of the engine is enhanced. A specific revolution speed suitable for reducing the emissions of air pollutants is stored, and an engine (7) is controlled using the specific revolution speed as a target revolution speed for the engine. The absorption torque of a hydraulic pump (6) is subjected to a high-pass filtering process whereby a high-frequency component devoid of a trend component is obtained. Target assist torque is computed from the high-frequency component, and an assist electric motor (10) is subjected to power running/generation control accordingly. A specific output torque range suitable for reducing the emissions of air pollutants is stored, and the target assist torque is corrected so that the trend component does not exceed the specific output torque range.