Float-Based Flow Measurement Device for Fuel Injection Systems
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Solution Overview
Problem
Conventional flow amount measuring devices for fluid injection valves face challenges in accuracy due to pressure pulsation caused by gear pump rotation and difficulty in measuring intermittent injections, especially in fuel injection systems for internal combustion engines, where the delay in pressure difference detection leads to incorrect rotation measurements.
Innovation Solution
A flow amount measuring device with a housing divided into two fluid chambers, where a movable member slides between them, allowing fluid to be supplied from one chamber to the injection valve, generating a pressure difference that moves the member in proportion to the flow amount, enabling precise measurement of the flow amount based on the member's movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a gear pump is rotated to cancel pressure difference, then the flow amount can be detected, but pressure pulsation occurs which makes piston position unstable and reduces measurement accuracy
Solution Approach 1:
The invention extracts the gear pump rotation mechanism from the measurement system and replaces it with a direct pressure difference detection method. The pressure sensor directly measures the pressure difference between upstream and downstream sides without requiring gear pump rotation, thereby eliminating pressure pulsation-induced instability while maintaining measurement capability.
Solution Approach 2:
The invention replaces the mechanical gear pump rotation system with an electronic pressure difference detection system. Instead of using mechanical piston movement driven by gear pump rotation, the system uses a pressure sensor to directly detect pressure differences, substituting mechanical measurement with electronic sensing to eliminate mechanical instability.
2Measurement precision
If the gear pump is rotated to measure flow amount, then continuous flow can be measured, but intermittent injection flow amount cannot be measured with high accuracy due to delay in pressure difference detection
Solution Approach 1:
The invention performs preliminary action by directly detecting pressure difference at the moment of injection without waiting for gear pump rotation to cancel pressure difference. The pressure sensor immediately captures the pressure change when the injection valve opens, eliminating the delay period and enabling accurate measurement of intermittent injection flow amounts from the first injection.
3Measurement precision
If the detected rotation amount during delay period is neglected, then measurement accuracy may be improved, but the number of injections must be increased to diminish incorrectness influence
Solution Approach 1:
The invention enables the system to self-correct by using the pressure difference detection to automatically compensate for the delay period effect. The pressure sensor continuously monitors pressure changes, and the control unit processes these changes in real-time, allowing accurate measurement without requiring manual correction or increasing the number of injections.
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 allows for accurate measurement of fluid flow with a small number of injections, reducing measurement time and accounting for variations among different fluid injection valves, while minimizing the impact of air variations and pressure pulsation, resulting in high accuracy and efficient operation.
Implementation Method 1
When the fluid is supplied from the source of the injection fluid to one of the fluid chambers, the fluid is supplied from the other fluid chamber to the fluid injection valve. Therefore, when the fluid injection is carried out by the fluid injection valve, a pressure difference is generated between the first and second fluid chambers. The movable member is moved by the pressure difference.
Data Source
AI summary
A measuring body is provided in a fluid path between a pump and a fuel injection valve, a flow amount for which is measured. An inner space of the measuring body is divided into a first and a second fluid chambers by a partitioning wall, wherein the first and second fluid chambers are, respectively, operatively connected to the pump and the fuel injection valve. A movable member (float) is slidably inserted into a through-hole formed in the partitioning wall, so that both ends are respectively exposed to the first and second fluid chambers. When the fuel injection is carried out by the fuel injection valve, the fluid in the second fluid chamber is decreased corresponding to the amount of injected fluid, and thereby the float is moved in a direction from the first to the second fluid chamber. The amount of the injected fluid is measured by detecting the movement of the float.