Throttle Device Turbulent Flow Fuel Injection
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Solution Overview
Problem
The heating of the piezo stack in fuel injection devices causes working heat to be transferred to the fuel, leading to increased temperature and reduced fuel injection efficiency, as the pressure in the control chamber fails to decrease, preventing the injection needle from opening properly and reducing the fuel injection quantity.
Innovation Solution
A throttle device with an inlet throttle designed to create a turbulent flow, maintaining a constant flow coefficient over temperature ranges, and an inclined outlet throttle to manage pressure and mass flow, ensuring the pressure in the control chamber remains constant, allowing for consistent fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the piezo stack is arranged inside the housing, then the device complexity is reduced and space is saved, but the working heat generated by the piezo stack heats up the fuel, causing the fuel temperature to increase and the injection quantity to decrease
Solution Approach 1:
The patent converts the harmful thermal effect (heating of fuel reducing injection quantity) into a beneficial control parameter. By deliberately designing the inlet throttle to create turbulent flow, the system uses the heated fuel's altered flow characteristics to maintain stable mass flow through turbulence-induced flow coefficient stability, thus converting the thermal harm into a controlled operational benefit
2Temperature
If the fuel temperature increases due to working heat, then the fuel viscosity changes, but the flow coefficient in laminar flow becomes temperature-dependent, causing mass flow to increase and control chamber pressure to rise
Solution Approach 1:
The patent changes the flow regime parameter from laminar to turbulent by optimizing the inlet throttle geometry (length and diameter). This parameter change makes the flow coefficient independent of temperature variations, thereby stabilizing the mass flow and control chamber pressure despite fuel temperature increases during operation
3Stress or pressure
If the control chamber pressure increases without proper pressure reduction, then the injection needle cannot open properly, but reducing pressure without turbulent flow causes temperature-dependent mass flow variations
Solution Approach 1:
The patent creates a self-regulating system where the turbulent flow through the optimized inlet throttle provides automatic feedback stabilization. As fuel temperature rises and viscosity changes, the turbulent flow regime maintains a stable flow coefficient that naturally compensates for temperature effects, providing feedback-based pressure control without additional active components
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 maintains a consistent fuel injection quantity by keeping the pressure in the control chamber constant, preventing the reduction in fuel injection efficiency due to temperature increases, ensuring the fuel injection nozzle operates effectively over time.
Implementation Method 1
The length Lz of the inlet throttle is selected such that fuel flowing through the inlet throttle during operation flows through the inlet throttle in a turbulent flow
Implementation Method 2
During operation, the piezo stack heats up and transfers the working heat generated in this way to the housing and the components of the injection device arranged in the vicinity. Since fuel that is sent to the fuel injector flows past this area, the working heat is automatically dissipated to the fuel
Data Source
Figure 1
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AI summary
The invention relates to a throttle device (16) for controlling an amount of fuel (12) to be supplied to a fuel injection nozzle (14), comprising a control area (20) and a supply device (18) for supplying fuel (12) to said control area (20), the supply device (18) having a supply throttle (44) of a length (Lz) selected such that a fuel (12) flowing through the supply throttle (44), when in operation, flows through said supply throttle (44) in a turbulent flow (48). The invention also relates to an injection device (10) that comprises said throttle device (16).