Engine Idle Speed Control for Mobile Work Devices
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Solution Overview
Problem
Existing methods for reducing engine speed in mobile work machines to minimize fuel consumption and emissions while complying with emission limits face challenges, as extending the certified speed range leads to irrelevant test points and operational difficulties.
Innovation Solution
A method that reduces engine idle speed below the certified minimum speed range when specific conditions are met, such as a predetermined idle period within the certified range, ensuring compliance with emission targets and avoiding unnecessary speed extensions, with a control unit managing these conditions to prevent engine stalling and maintain efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the certified working speed range is extended to lower speeds to enable reduced idle speed operation, then fuel consumption and emissions can be reduced, but irrelevant test points are shifted to lower speeds and operational difficulties arise
Solution Approach 1:
The patent segments the speed range into two distinct zones: a certified working speed range (n0 to nmax) for normal operation and certification, and an uncertified lower speed range (below n0) for idle operation. This segmentation allows the system to operate at lower speeds for fuel savings without complicating the certification process, as the certified range remains unchanged.
Solution Approach 2:
The patent dynamically adjusts the engine speed based on operational conditions, transitioning between the certified idle speed n0 and lower uncertified speeds below n0. The control system monitors parameters such as coolant temperature, oil pressure, and electrical load to determine when to operate in the uncertified lower speed range, enabling flexible optimization of fuel consumption without permanent certification changes.
2Loss of energy
If the engine idle speed is reduced below the minimum certified speed to minimize fuel consumption and emissions, then resource conservation is achieved, but emission compliance outside the certified range must be ensured
Solution Approach 1:
The patent performs preliminary verification by comparing emissions at the lower uncertified idle speed with emissions at the certified idle speed n0 using the NRSC test cycle. This preliminary action ensures that operating below n0 will not violate emission limits before the system actually operates in this range, thereby maintaining emission compliance while enabling fuel savings.
Solution Approach 2:
The control system continuously monitors engine parameters and operational conditions to determine when to transition between certified and uncertified speed ranges. Feedback from sensors monitoring coolant temperature, oil pressure, electrical load, and hydraulic system status ensures that the engine operates below n0 only when conditions are favorable, maintaining both fuel efficiency and emission compliance.
3Object-generated harmful factors
If the engine operates at lower idle speed outside the certified range, then fuel consumption and noise emissions are reduced, but additional control conditions and monitoring are required
Solution Approach 1:
The control system integrates multiple functions into a single unified controller that manages both certified and uncertified speed ranges. This multi-functional controller handles normal operation within the certified range, idle operation below n0, transitions between modes, and monitoring of various parameters (coolant temperature, oil pressure, electrical load), thereby reducing overall system complexity despite the added capability.
Solution Approach 2:
The patent changes the operating parameter of engine speed from the fixed certified idle speed n0 to a variable speed that can operate below n0 when conditions permit. This parameter change is accompanied by adjustments in other parameters such as fuel injection timing and air intake to maintain optimal combustion characteristics, thereby reducing noise and emissions while managing control complexity through coordinated parameter adjustment.
Data Source
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AI summary
The present invention relates to a method for controlling a work device, in particular a mobile work device and preferably a wheel loader, wherein the work device has at least one internal combustion engine which can be operated in at least one idle mode, and wherein the method comprises the step of reducing the engine speed in idle mode below the minimum speed of a certified speed range (t2, idle reduced) when at least one condition is met.