Fuel Pump Pressure Sensing via Current and Speed Characteristic Curves
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Solution Overview
Problem
Modern motor vehicles lack a direct method for the engine control to infer the state of the fuel supply system without a fuel pressure sensor, necessitating an alternative for detecting and regulating fuel pump operating pressure effectively.
Innovation Solution
A device and method utilizing a speed detection device, pump current detector, memory device, and pressure determination device to determine fuel pressure based on a pump current/speed characteristic curve field with hysteresis, allowing for intelligent characteristic diagram evaluation and map-based pressure control without a pressure sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a pressure sensor is used to directly measure fuel pressure, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces intermediate measurement parameters (pump current and pump speed) that indirectly reflect fuel pressure. Instead of directly measuring pressure with a sensor, the system measures electrical parameters (current drawn by the pump motor) and mechanical parameters (pump rotation speed), then uses these as intermediaries to infer pressure through characteristic curve evaluation. This intermediary approach eliminates the need for direct pressure sensing while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical/physical pressure sensing system with an electrical measurement and evaluation system. Rather than using a mechanical pressure sensor to detect fuel pressure directly, the system uses electrical measurements (pump motor current) combined with computational evaluation of characteristic curves to determine pressure. This substitution eliminates complex mechanical sensing components while achieving the same functional goal.
2Measurement precision
If a pressure sensor is installed in the fuel supply system, then fuel pressure detection accuracy is improved, but system cost increases
Solution Approach 1:
The patent replaces expensive pressure sensors with inexpensive measurement components (current sensors and speed sensors) that are already standard in fuel pump systems. By using readily available, low-cost components and eliminating the need for specialized pressure sensing equipment, the system achieves pressure detection functionality at a fraction of the cost of traditional sensor-based solutions.
Solution Approach 2:
The system uses the fuel pump's own operational parameters (current consumption and rotation speed) to determine fuel pressure, rather than requiring separate measurement devices. The pump's inherent operational characteristics serve as the measurement basis, eliminating the need for additional expensive sensing components and simplifying the overall system architecture.
3Device complexity
If no pressure sensor is used, then device complexity is reduced, but the ability to regulate fuel pressure locally is worsened
Solution Approach 1:
The patent implements a feedback mechanism where the determined fuel pressure (derived from pump current and speed measurements) is fed back to the control system. This feedback enables the control unit to adjust pump operation to maintain desired pressure levels, achieving local pressure regulation without requiring direct pressure sensing. The characteristic curve evaluation provides the necessary feedback information for closed-loop control.
Solution Approach 2:
The system uses intermediate calculations based on pump current and speed measurements as mediators to achieve pressure regulation. Rather than directly sensing pressure for feedback control, the system computes pressure from electrical and mechanical measurements, then uses this computed information to regulate pump operation. This intermediary approach maintains regulation capability while avoiding complex pressure sensing infrastructure.
4Measurement precision
If additional reference points are added to the characteristic curve, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent performs preliminary determination of the characteristic curve during system setup or calibration phases. Reference points and the characteristic curve are pre-established based on pump testing and characterization, storing the relationship between pump current, speed, and resulting fuel pressure. This preliminary action allows the system to use a comprehensive, high-precision characteristic curve without adding real-time measurement complexity, as the complex evaluation work is done in advance.
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
Enables local pressure regulation, map-based pressure control, and additional reference points for the fuel pump, reducing system costs and minimizing the influence of viscosity and temperature on pressure measurement accuracy, while providing local control and system protection.
Implementation Method 1
a memory device which is designed to store a pump current/speed characteristic curve field with at least two pressure reference points determined by a hysteresis of a pressure switch
Data Source
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AI summary
The invention relates to a device (1) for sensing an operating pressure of a fuel pump (100) for a motor vehicle, wherein the device comprises: a rotational-speed sensing apparatus (10), which is designed to sense a rotational speed of the fuel pump (100); a pump-current sensing apparatus (20), which is designed to sense an electric pump drive current of the fuel pump (100); a memory apparatus (30), which is designed to store a pump current/rotational speed characteristic curve set having at least two pressure reference points determined by means of a hysteresis of a pressure switch; and a pressure-determining apparatus (40), which is designed to determine a fuel pressure prevailing in the fuel pump (100) on the basis of the sensed rotational speed, the sensed pump drive current, and the stored pump current/rotational speed characteristic curve set.