High-Pressure Pump Dead Center Detection via Coil Current
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Solution Overview
Problem
In high-pressure injection systems of motor vehicles, accurately determining the top dead center rotation position of the piston is challenging due to manufacturing tolerances and geometric variations, leading to inefficient fuel delivery and potential failure in conveying fluid.
Innovation Solution
A method involving the application of a coil current to the electromagnet during and after overshooting the top dead center, detecting a start time based on a change criterion in the coil current profile, and back-calculating the dead center rotation position, which allows for precise estimation without requiring complex position measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the dead center rotation position is estimated inaccurately due to manufacturing tolerances and geometric variations, then the fuel pump conveys undesirably small quantities of fluid and has low efficiency, but implementing complex position measurement systems to improve precision increases device complexity and cost
Solution Approach 1:
The inlet valve serves dual functions: it closes during the delivery phase to enable fuel compression and delivery, and subsequently opens during the inlet phase due to pressure differential. This self-opening behavior provides a natural signal that can be detected by the electromagnet's coil current, eliminating the need for separate position sensing mechanisms while enabling precise dead center detection
Solution Approach 2:
The control device monitors the coil current of the electromagnet to detect the moment when the inlet valve opens. This feedback signal indicates the piston's position relative to dead center, allowing the system to dynamically adjust the actuation timing based on actual mechanical conditions rather than relying on pre-calibrated or estimated positions
2Measurement precision
If calibration is performed to ascertain the relationship between motor shaft rotation position and top dead center, then measurement precision improves, but calibration procedures increase time consumption and operational complexity
Solution Approach 1:
The system automatically determines the dead center position by detecting when the inlet valve opens, using the valve's own mechanical response to pressure changes as the signal source. This eliminates the need for manual calibration procedures while achieving high measurement precision
Solution Approach 2:
The inlet valve acts as an intermediary that translates mechanical position information into an detectable electrical signal through its interaction with the electromagnet's coil current. This intermediary mechanism provides a natural, calibration-free method for determining dead center position
3Measurement precision
If the inlet valve closing time is precisely controlled during the delivery phase, then fuel delivery quantity and pressure regulation precision improve, but the system becomes more sensitive to timing errors and requires higher measurement precision
Solution Approach 1:
The system uses feedback from the coil current signal that indicates when the inlet valve opens to dynamically determine the dead center position. This allows the control system to compensate for variations in piston geometry and manufacturing tolerances, reducing sensitivity to timing errors while maintaining precise control
Solution Approach 2:
Instead of using fixed, pre-calibrated timing values, the system dynamically determines the dead center position for each operating cycle based on actual valve opening detection. This dynamic adaptation makes the system more robust to variations while maintaining precise control
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 enables accurate determination of the dead center rotation position, ensuring efficient fuel delivery and maintaining high-pressure pump efficiency by avoiding unnecessary fluid conveyance issues.
Implementation Method 1
The inlet valve is closed by a control device by application of current to an electromagnet
Implementation Method 2
a start time is detected, at which start time the coil current, on account of starting of an opening movement of the inlet valve, fulfills a predetermined change criterion
Data Source
AI summary
Various embodiments include methods for operating a high-pressure pump comprising: driving a piston arranged in a compression chamber with a motor shaft; during movement of the piston toward the top dead center, closing the inlet valve so the fluid is then delivered by the piston through an outlet valve; applying a coil current to an electromagnet used to close the inlet valve during and/or after overshooting the top dead center; detecting a start time at which the coil current, on account of starting of an opening movement of the inlet valve, fulfills a predetermined change criterion; labelling a dead center rotation position of the motor shaft at which the piston is at the top dead center based at least in part on the ascertained start time; and adjusting operation of the pump based on the identified dead center rotation position.