Fuel Pump Calibration via Current Detection
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Solution Overview
Problem
Existing methods for controlling fuel pumps in internal combustion engines face challenges such as the need to avoid direct pressure measurement, adaptation to wear and unmeasured variables, and calibration complexity, especially during overrun operations where fuel demand is low.
Innovation Solution
A method that maintains the rotational speed of the fuel pump constant during overrun operations, detects the pump current, and uses this data to calibrate the characteristic map, allowing for precise determination of pressure and volume flow to correct the calibration valve, thereby reducing fuel consumption and system instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rotational speed of the fuel pump is varied during overrun operation to perform calibration, then the calibration data can be collected, but the fuel consumption increases and system stability deteriorates
Solution Approach 1:
The fuel pump uses its own operational characteristics during normal overrun operation to perform self-calibration. The system leverages the existing pump operation and measures the relationship between pump current and pressure without requiring external intervention or deviation from normal operating conditions, allowing the pump to calibrate itself while maintaining efficient fuel consumption.
Solution Approach 2:
The calibration method utilizes changes in electrical parameters (pump current) rather than mechanical parameters (rotational speed) to achieve calibration. By monitoring the pump current at constant rotational speed during overrun operation, the system can determine pressure values and update calibration data without altering the mechanical operating conditions that would increase fuel consumption.
2Measurement precision
If the rotational speed of the fuel pump is changed during calibration, then calibration data can be obtained, but the system stability and operational smoothness deteriorate
Solution Approach 1:
The patent replaces mechanical measurement methods (varying rotational speed) with electrical measurement methods (monitoring pump current). The calibration is achieved by measuring the electrical current drawn by the pump motor at constant speed, which correlates with the pressure being generated, thereby updating calibration data without any mechanical disturbance to the system.
Solution Approach 2:
The pump current serves multiple functions simultaneously: it drives the pump motor during normal operation and serves as the measurement signal for calibration purposes. This multi-functionality allows the same operational parameter to maintain system stability while providing the necessary data for calibration, eliminating the need for separate calibration operations.
3Measurement precision
If a direct pressure sensor is installed in the low-pressure circuit, then pressure measurement is accurate, but the system complexity and cost increase
Solution Approach 1:
The pump current acts as an intermediary parameter that indirectly indicates the pressure in the low-pressure circuit. Instead of directly measuring pressure with a sensor, the system uses the electrical current drawn by the pump motor as a proxy measurement, which correlates with the pressure being generated. This intermediary approach provides sufficient calibration data without requiring direct pressure sensing hardware.
Solution Approach 2:
The patent substitutes mechanical pressure sensing with electrical measurement. By monitoring the electrical parameters of the pump motor (current, power consumption), the system obtains pressure-related information without installing mechanical pressure sensors in the fuel circuit, thereby reducing system complexity and cost while maintaining adequate measurement precision for calibration purposes.
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 enables accurate calibration of fuel pump parameters without noticeable changes in behavior, ensuring efficient operation and reducing fuel consumption, even during low-load conditions, by maintaining a stable rotational speed and detecting pump current changes to adjust pressure settings.
Implementation Method 1
the rotational speed of the pump is maintained substantially unchanged during the calibration
Implementation Method 2
in the event of the triggering pressure of a calibration valve arranged on the pressure side of the pump being attained
Implementation Method 3
the pump current is detected
Data Source
AI summary
A method for operating an internal combustion engine, in which fuel is supplied to the internal combustion engine by a rotary pump, and the speed of the pump and/or the electrical current for feeding the pump (pump current) is controlled in accordance with a requirement variable, taking into account a determination specification. When in an overrun mode, a calibration is carried out and the speed of the pump is detected and is maintained during the calibration step. Once the triggering pressure for a calibration valve, arranged on the high-pressure side of the pump, has been reached, the pump current is detected and the determined speed and the determined pump current are used to calibrate the determination specification. A calibration in the overrun mode is performed without alteration to the speed of the fuel pump. This prevents a variable behaviour of the fuel pump which might produce undesired operating conditions.