Suction Jet Pump Bypass Valve for Fuel Foam Control
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Solution Overview
Problem
Suction jet pumps often experience foam formation in storage tanks when fuel levels are low, leading to dynamic leakage due to air being sucked in, which displaces fuel and results in partial emptying of the tank, especially when the characteristic curve of the suctioned volume flow is steep.
Innovation Solution
Incorporating a bypass opening in the drive line that opens into the suction chamber, creating additional flow resistance dependent on the motive flow, which acts on the valve member to reduce foam formation by flattening the characteristic curve and maintaining suction capacity above the minimum while below the foam limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the suction opening is enlarged to increase suction capacity, then the intake flow increases, but foam formation increases and air is sucked in
Solution Approach 1:
The invention changes the flow parameters by introducing a bypass opening that creates flow resistance dependent on motive flow. This modifies the characteristic curve to flatten it, allowing the suction capacity to be maintained above minimum while keeping the intake flow below the foam limit, thus resolving the contradiction between productivity and foam formation
Solution Approach 2:
The bypass opening creates a feedback mechanism where the motive flow generates additional flow resistance that acts on the valve member. This self-regulating feedback controls the suction opening area dynamically, preventing excessive suction capacity that would lead to foam formation while maintaining adequate intake flow
2Productivity
If the suction opening area is increased to maintain suction capacity above minimum, then the intake flow increases, but air intake and foam formation occur
Solution Approach 1:
The bypass opening modifies the flow parameters to create a flatter characteristic curve, enabling the system to operate in a range where suction capacity remains above minimum while intake flow stays below the critical foam limit, thus preventing air intake and foam formation
Solution Approach 2:
The bypass opening acts as an intermediary element that introduces additional flow resistance into the system. This intermediary mechanism controls the relationship between motive flow and suction capacity, preventing direct coupling that would lead to air intake when suction capacity is high
3Object-affected harmful factors
If a pressure relief valve is added upstream of the jet outlet to reduce foam formation, then the device complexity increases, but the characteristic curve remains steep
Solution Approach 1:
The bypass opening serves multiple functions simultaneously: it creates additional flow resistance dependent on motive flow, acts on the valve member to control suction opening, and flattens the characteristic curve. This multi-functionality eliminates the need for separate pressure relief valves, reducing device complexity while preventing foam formation
Solution Approach 2:
The invention merges the foam prevention function with the existing drive line structure by incorporating the bypass opening directly into it. This integration combines the flow resistance generation and valve control functions into a single structural element, avoiding the need for additional separate valves or complex control mechanisms
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
The solution effectively reduces or avoids foam formation, preventing partial emptying of the storage tank by regulating the suction power and maintaining efficient fuel intake, even at low fuel levels, thus enhancing the pump's self-regulation and operational reliability.
Implementation Method 1
an additional flow resistance that is directly dependent on the motive flow is generated at the intake opening
Implementation Method 2
a motive flow is introduced into the suction chamber (3) in the form of a jet via the motive line (1) and its jet outlet (2)
Implementation Method 3
The motive flow of the motive line (1) entrains surrounding fluid from the suction chamber (3) into the mixing channel (4)
Implementation Method 4
A valve member (6) is provided on the suction opening (5), which valve member cooperates with the suction opening (5) and forms a check valve with it
Data Source
Figure 1
AI summary
Suction jet pumps are already known with a driving line (1) which leads via a jet outlet into a suction chamber (3), wherein the suction chamber has a suction opening (5) which interacts with a valve element (6) and through which fluid can be sucked into the suction chamber. The valve element together with the suction opening forms a suction valve. The suction jet pump is driven by a driving stream flowing via the driving line. The suction jet pump is arranged in a storage tank (11) and sucks fuel out of a fuel tank into the storage tank. At low levels in the fuel tank, air may sometimes be sucked up and conducted into the storage tank, as a result of which foaming occurs in the storage tank. However, the large volume of the foam causes fuel to be displaced, which may result in partial emptying of the storage tank. This effect is also referred to as dynamic leakage. A characteristic curve of the suction jet pump that represents the suction power as a function of the driving stream has a comparatively steep gradient. Severe foaming occurs only above a critical suction power of the suction jet pump, referred to below as the foam limit. In the case of the suction jet pump according to the invention, foaming is avoided or at least reduced. According to the invention, it is provided that the driving line has a bypass opening (10) which leads into the suction chamber and is arranged in such a manner that the bypass stream thereof acts on the valve element.