Road-Building Engine Speed Control for Hydraulic Load Matching
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Solution Overview
Problem
Internal combustion engines in road construction machines often operate at inefficient speeds due to fixed power requirements, leading to unnecessary fuel consumption, environmental pollution, and energy wastage, particularly during varying load conditions and operations.
Innovation Solution
The speed of the internal combustion engine is automatically adjusted to match the current power requirements of active work units, minimizing residual volume flows through fixed displacement pumps and flow valves, allowing for energy-optimized operation by varying the engine speed to reduce residual volume flows to approximately zero.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the internal combustion engine operates at constant rated speed to ensure sufficient power supply, then the power supply reliability is improved, but fuel consumption increases and environmental pollution worsens
Solution Approach 1:
The patent implements dynamic speed adjustment of the internal combustion engine based on real-time monitoring of hydraulic system power requirements. The control system continuously evaluates the power demands of working units and adjusts engine speed accordingly, transitioning from static rated speed operation to dynamic adaptive speed control, thereby optimizing fuel consumption while ensuring sufficient power supply.
Solution Approach 2:
The patent employs a feedback control mechanism where the control system monitors hydraulic system parameters (flow rates, pressures, power requirements) and uses this information to adjust engine speed. This closed-loop feedback ensures that the engine operates at optimal speed to meet actual power demands, preventing both energy waste from excessive speed and power deficiency from insufficient speed.
2Reliability
If the internal combustion engine operates at constant rated speed to maintain power availability, then the power supply stability is improved, but environmental pollution increases
Solution Approach 1:
The system dynamically adjusts engine speed based on actual hydraulic system requirements, reducing engine speed and associated emissions during periods of lower power demand while maintaining power availability when needed. This dynamic operation significantly reduces environmental pollution compared to continuous rated speed operation.
Solution Approach 2:
The patent changes the operating parameter (engine speed) from a fixed constant to a variable parameter that adapts to system needs. By adjusting speed as a controllable parameter, the system maintains power supply stability while minimizing harmful emissions during lower demand periods.
3Loss of energy
If the engine speed is reduced to decrease fuel consumption, then energy efficiency is improved, but the power supply to working units may become insufficient
Solution Approach 1:
The control system continuously monitors hydraulic system power requirements and provides feedback to the engine speed control. This feedback mechanism ensures that engine speed is reduced only when system power requirements are met at lower speeds, preventing power deficiency while maximizing energy efficiency.
Solution Approach 2:
The system performs preliminary evaluation of power requirements before reducing engine speed. The control system assesses current and anticipated power demands, and only reduces speed when it determines that sufficient power will be available, thereby preventing power supply insufficiency.
4Device complexity
If fixed displacement pumps are used to drive hydraulic motors, then device complexity is reduced, but residual volume flow causes energy wastage
Solution Approach 1:
The patent changes the parameter being controlled from pump displacement (fixed) to engine speed (variable). By keeping pump displacement fixed but varying engine speed, the system maintains simple fixed displacement pump hardware while achieving energy optimization by matching pump output flow to actual system requirements through speed control.
Solution Approach 2:
The system introduces dynamic engine speed control to compensate for the static nature of fixed displacement pumps. This dynamic adjustment of engine speed allows the hydraulic system to adapt to varying power requirements without requiring complex variable displacement pumps, thereby reducing residual volume flow energy losses while maintaining device simplicity.
Data Source
Figure 1
AI summary
A method for adjusting the rotational speed of an internal combustion engine of a road-building machine which, in addition to a traction drive, has hydraulic motors which are connected to the internal combustion engine and which serve for driving working assemblies, in which method the rotational speed is adjusted as a function of the present power demand of the working assemblies, characterized in that the hydraulic motors are operated using fixed-displacement pumps, and residual volume flows presently to be discharged are reduced by flow valves for hydraulic motors of active working assemblies, for which purpose the rotational speed of the internal combustion engine is automatically adapted during working operation.