Speed-Controlled Fluid Pump Pressure Limiting via Current Thresholds
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Solution Overview
Problem
Existing speed-controlled fluid pumps in motor vehicles lack reliable operation under varying environmental conditions without direct fuel pressure measurement, leading to potential overpressure issues and increased costs due to the absence of fuel pressure sensors.
Innovation Solution
A method and device for a speed-controlled fluid pump that uses a maximum and threshold control current to limit pressure, with the threshold value specified based on boundary conditions, allowing for intelligent pressure management without a pressure sensor, potentially replacing mechanical relief valves and accounting for ambient temperature and viscosity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuel pressure sensor is installed to directly measure fuel pressure, then the reliability of fuel supply system monitoring is improved, but the system cost increases
Solution Approach 1:
The fuel pump control unit performs self-monitoring by measuring its own current consumption and calculating fuel pressure based on pre-stored characteristic maps that correlate current consumption with pressure under various boundary conditions. This eliminates the need for an external pressure sensor while maintaining monitoring reliability.
Solution Approach 2:
The mechanical pressure sensor is replaced by an electronic calculation system that uses the control unit's existing sensors (current measurement) and stored characteristic data to determine pressure values, substituting direct mechanical measurement with indirect electronic computation.
2Reliability
If a mechanical pressure relief valve is installed to limit maximum pressure, then system protection against overpressure is improved, but the device complexity and cost increase
Solution Approach 1:
The mechanical pressure relief valve is replaced by an electronic control mechanism that monitors calculated pressure values and adjusts the fuel pump's current consumption accordingly. When pressure approaches the maximum limit, the control unit reduces pump current to maintain pressure below the threshold, eliminating the need for mechanical relief components.
Solution Approach 2:
The system implements closed-loop feedback by continuously monitoring current consumption, calculating pressure based on stored characteristics, comparing the calculated pressure against the maximum pressure limit, and adjusting pump operation to maintain pressure within safe boundaries.
3Productivity
If the pump operates at maximum power to ensure sufficient fuel supply, then fuel delivery capability is improved, but the risk of overpressure increases
Solution Approach 1:
The fuel pump operation transitions from static maximum power delivery to dynamic control where the control unit continuously adjusts pump current based on real-time boundary conditions (temperature, viscosity, engine load) and calculated pressure values, optimizing fuel delivery while preventing overpressure.
Solution Approach 2:
The system changes the operating parameters of the fuel pump dynamically by adjusting current consumption levels based on stored characteristic maps that relate current, pressure, and boundary conditions, allowing the pump to operate at optimal power levels rather than constant maximum power.
Data Source
Figure 1~2
AI summary
A method for operating a speed-controlled fluid pump (102) comprises: - providing an electrical control current for the fluid pump (102), - providing a maximum value (201) for the control current, which corresponds to a maximum permissible pressure on the outlet side of the fluid pump (102), - providing a threshold value (202) for the control current, which corresponds to another maximum permissible pressure on the outlet side of the fluid pump (102) and which is specified depending on at least one boundary condition, wherein the threshold value (202) is lower than the maximum value (201), - controlling the fluid pump (102) with at most the threshold value (202) of the control current when the existence of the boundary condition has been determined, in order to limit the pressure on the outlet side of the fluid pump (102) to a value provided for the boundary condition.