Engine Speed Measurement Using Pump Pressure Oscillations
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Solution Overview
Problem
Existing engine speed measurement systems are inaccurate at low engine speeds and increase system complexity and cost with additional sensors.
Innovation Solution
A system using a positive displacement pump connected to an engine's rotor shaft, with a pressure sensing device and processing unit to determine engine speed from periodic oscillations in the pump's fluid output, allowing for accurate speed measurement without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated speed sensors are used for engine speed measurement, then speed measurement capability is provided, but measurement precision deteriorates at low engine speeds
Solution Approach 1:
The patent applies multi-functionality by using an existing pressure sensor (originally designed for monitoring fuel pump inlet pressure) to also measure engine speed. The pressure sensor detects periodic pressure oscillations at the fuel pump inlet caused by the pump's operation, and the frequency of these oscillations corresponds to the engine speed. This allows a single sensor to serve dual purposes: pressure monitoring and speed measurement, eliminating the need for dedicated speed sensors while maintaining measurement capability across all engine speeds including low speeds.
2Reliability
If additional speed sensors are provided for redundancy, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The patent eliminates the need for additional speed sensors by making the existing pressure sensor multi-functional. The pressure sensor's output signal is processed to extract both pressure information and speed information. The processing unit analyzes the frequency content of the pressure signal to determine engine speed, providing redundant speed measurement capability without adding any physical speed sensors to the system.
Solution Approach 2:
The system applies self-service by using the pressure sensor's own output signal for dual purposes. The same signal that provides pressure monitoring data also contains embedded speed information that can be extracted through frequency analysis. This self-service approach provides measurement redundancy without requiring external additional sensors, thereby reducing system complexity while improving reliability.
3Reliability
If additional speed sensors are provided for redundancy, then measurement reliability is improved, but manufacturing cost increases
Solution Approach 1:
The patent reduces manufacturing cost by making the existing pressure sensor multi-functional. The pressure sensor originally installed for fuel system monitoring is also used for speed measurement, eliminating the need to purchase and install additional dedicated speed sensors. The processing unit extracts speed information from the pressure signal's frequency characteristics, providing redundant measurement capability without any additional hardware cost.
Solution Approach 2:
The system achieves cost reduction through self-service, where the pressure sensor's output signal serves dual purposes. The same electrical signal provides both pressure monitoring data and speed measurement data after frequency analysis. This eliminates the need for additional sensor hardware, reducing both component costs and installation costs while maintaining measurement reliability through redundant information extraction.
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 method provides accurate engine speed measurement across all speed ranges, reducing system complexity and cost by leveraging existing pressure transducers, and enabling precise control of engine operation.
Implementation Method 1
a positive displacement pump drivingly connected to a rotor shaft of the engine, the pump having an inlet for receiving a fluid supply and an outlet for outputting pressurized fluid
Implementation Method 2
a pressure sensing device provided at an inlet of the pump, receiving, from the pressure sensing device, a sensor signal comprising a series of periodic oscillations
Implementation Method 3
determining a frequency of the oscillations, the frequency proportional to a rotational speed of the rotor shaft
Data Source
AI summary
A system and method for measuring a speed of an engine are provided. The engine has a positive displacement pump drivingly connected to a rotor shaft thereof, the pump having an inlet for receiving a fluid supply and an outlet for outputting pressurized fluid. A sensor signal is received from a pressure sensing device provided at an inlet of the pump, the sensor signal comprising a series of periodic oscillations. A frequency of the oscillations is determined, the frequency proportional to a rotational speed of the rotor shaft. The speed of the engine is then determined from the frequency of the oscillations and the speed of the engine as determined is output for controlling operation of the engine.