Fuel Pump Control Unit Pressure Limiting via Motor Current
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Solution Overview
Problem
Fuel systems in vehicles face reliability issues due to the absence of mechanical pressure-limiting valves and the need for rapid pressure increase to meet emissions standards, leading to potential system failures and pressure overshoots, especially in modern vehicles without fuel pressure sensors.
Innovation Solution
A control unit in the fuel pump system calculates the current system pressure based on the electric motor's speed and operating current, generating signals to limit the current and speed when pressure exceeds predefined limits, effectively replacing mechanical pressure relief valves and enabling quicker pressure control without mechanical delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a mechanical pressure relief valve is used to limit system pressure, then system pressure can be limited, but system reliability decreases due to additional mechanical components that can fail
Solution Approach 1:
The patent replaces the mechanical pressure relief valve with an electronic control system that uses a pressure sensor to detect system pressure and an electronic motor controller to regulate motor speed. This substitution eliminates mechanical failure points while maintaining pressure limitation functionality through electronic feedback control.
Solution Approach 2:
The patent implements a feedback control system where a pressure sensor continuously monitors system pressure and provides signals to the control unit. The control unit adjusts motor operating current based on this feedback to maintain pressure within desired limits, replacing the passive mechanical valve with an active electronic regulation system.
2Speed
If the pump operates with maximum angular acceleration to achieve rapid pressure increase, then pressure rise time is reduced, but pressure spikes occur in the pumped medium
Solution Approach 1:
The patent applies dynamic control of the motor speed rather than fixed mechanical acceleration ramps. The electronic controller can adjust motor operating current in real-time based on feedback from the pressure sensor, enabling smooth acceleration and deceleration profiles that achieve rapid pressure rise without the rigid mechanical constraints that cause pressure spikes.
Solution Approach 2:
The patent changes the control parameter from fixed mechanical acceleration ramps to variable electronic current control. By dynamically adjusting the motor operating current based on actual system pressure feedback, the system can optimize acceleration rates to achieve fast pressure response while avoiding the pressure spikes caused by abrupt mechanical acceleration.
3Ease of manufacture
If no fuel pressure sensor is installed to reduce costs, then system cost is reduced, but the ability to detect and limit overpressure is lost
Solution Approach 1:
The patent makes the pressure sensor serve multiple functions: it provides feedback for electronic pressure limitation, enables monitoring for control purposes, and offers diagnostic capability for the engine control unit. This multi-functionality justifies the added cost by providing comprehensive system monitoring and control rather than simple pressure relief.
Solution Approach 2:
The patent implements feedback control by using the pressure sensor to continuously monitor system pressure and provide signals to the electronic motor controller. This feedback enables active pressure management and overpressure prevention, transforming the sensor from a cost addition into a critical component for system reliability and control.
4Stress or pressure
If a mechanical pressure relief valve is used, then system pressure can be limited, but system complexity and likelihood of failure increase
Solution Approach 1:
The patent merges the pressure limitation function with the existing electronic motor control system. The pressure sensor and electronic controller that already exist for other fuel injection purposes are utilized to also perform pressure limitation, eliminating the need for a separate mechanical pressure relief valve and reducing overall system complexity.
Solution Approach 2:
The patent enables the electronic motor control system to perform multiple functions: fuel delivery control, pressure regulation, and overpressure protection. This multi-functionality consolidates what would traditionally require separate mechanical components into a unified electronic control architecture, reducing system complexity.
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 solution enhances the reliability of the fuel delivery system by eliminating mechanical failures, allowing for rapid and precise pressure control independent of default values, reducing pressure overshoots, and preventing damage from excessive pressures.
Implementation Method 1
the control unit is configured to calculate the current system pressure of the conveying device as a function of the current rotational speed and operating current of the electric motor, based on a functional relationship between the system pressure of the conveying device, the operating current of the electric motor, and the rotational speed of the electric motor
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a delivery device 100 for delivering a medium in a vehicle 300 and for limiting a system pressure of the delivery device. In that context, the delivery device comprises a vehicle pump 101 which is driven by an electric motor 102. Further, the electric motor is controlled by a control unit 103, the control unit being designed to detect an actual rotational speed of the electric motor and an actual operating current of the electric motor. If the actual operating current of the electric motor exceeds a predefined operating current limit value, the control unit is designed to generate a first signal relating to a system pressure being exceeded. In that context, the predefined operating current limit value is dependent on the actual rotational speed of the electric motor.