Alternator Voltage Signal Analysis for Power Tool Engine Diagnostics
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Solution Overview
Problem
Modern internal combustion engines in portable power tools require multiple sensors to detect various operating parameters, leading to complexity, expense, and error sources, as well as problematic cable arrangements due to thermal loads in small-size tools.
Innovation Solution
The method involves deriving operating parameters from the voltage signal of an alternator, dividing a crankshaft revolution into crankshaft angle intervals, and correlating characteristic features of the voltage signal with engine speed to determine parameters like load, throttle position, and combustion course without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to detect operating parameters, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The voltage signal from the alternator serves multiple functions: it powers the ignition system and simultaneously provides data for detecting multiple operating parameters (engine speed, load, throttle position, combustion course). This multi-functional use of a single signal source eliminates the need for multiple dedicated sensors.
Solution Approach 2:
The alternator's voltage signal, which already exists for power generation, is utilized to detect operating parameters. The system uses its own operational characteristics (voltage signal variations) to monitor its state, eliminating the need for external sensing devices.
2Reliability
If multiple sensors are installed, then reliability of parameter detection is improved, but the number of error sources increases
Solution Approach 1:
The system uses the alternator's inherent voltage signal to detect operating parameters, eliminating external sensors that would introduce additional error sources. The voltage signal naturally reflects engine operating conditions, providing reliable data without additional failure points.
3Measurement precision
If cable arrangement is extended to connect sensors, then measurement capability is improved, but thermal load on cables increases
Solution Approach 1:
The invention extracts operating parameter information directly from the alternator's voltage signal, eliminating the need for separate sensor cables that would be exposed to thermal loads in the engine compartment.
Solution Approach 2:
The voltage signal serves dual purposes: powering the ignition system and providing measurement data, thereby eliminating the need for additional cable arrangements that would be subject to thermal stress.
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
This approach reduces the number of sensors needed, simplifies parameter detection, and allows for efficient energy use from the alternator to initiate control electronics, enabling effective diagnostic and servicing of power tools without the need for specialized sensors.
Implementation Method 1
a signal generator (16) is provided which is driven in rotation by the crankshaft and emits sequential alternating voltage signals for one crankshaft revolution
Data Source
AI summary
In a method for detecting an operating parameter of a power tool having an internal combustion engine with a cylinder, a piston delimiting a combustion chamber in the cylinder and driving a crankshaft supported rotatably in a crankcase, an intake supplying combustion air to the combustion chamber, an exhaust removing combustion gases from the combustion chamber, and a signal generator driven in rotation by the crankshaft emitting sequential alternating voltage signals, a period duration of the voltage signal is selected to correspond to the n-th portion of a crankshaft revolution with n greater than 2. The n-th portion of the crankshaft revolution provides a crankshaft angle interval. For each crankshaft angle interval at least one information is detected that represents a course plotted against the crankshaft angle. The course is scanned with regard to characteristic features that are correlated with an operating parameter of the power tool.