Fuel Injector Piezo Actuator Cooling via Annular Flow Path
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Solution Overview
Problem
Current fuel injection systems face challenges with piezo actuators overheating due to increased system pressure, leading to unreliable operation, as conventional piezo actuators have a temperature limit that is exceeded when fuel temperature rises significantly with higher pressures.
Innovation Solution
The fuel flowing into the piezo actuator's receiving space is cooled by routing it through an annular intermediate region between the nozzle clamping nut, nozzle body, and valve plate, where it can cool before reaching temperature-sensitive components, without requiring external fuel supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If system pressure is increased to improve fuel efficiency, then fuel injection efficiency is improved, but fuel temperature increases excessively causing piezo actuator overheating
Solution Approach 1:
The patent introduces a cooling channel as an intermediary element between the high-pressure fuel supply and the piezo actuator. This cooling channel acts as a mediator that allows heat transfer from the hot fuel to the channel walls, thereby cooling the fuel before it reaches the temperature-sensitive piezo actuator while maintaining the high system pressure needed for efficient fuel injection.
Solution Approach 2:
The patent segments the fuel flow path into distinct thermal zones. The fuel flow is divided into a high-temperature zone (after pressure reduction) and a low-temperature zone (after cooling channel passage). This segmentation allows the system to handle hot fuel for injection efficiency while protecting the piezo actuator through the cooled fuel path.
2Temperature
If additional cooling measures are implemented for piezo actuators, then temperature control is improved, but device complexity increases
Solution Approach 1:
The patent merges the cooling function with the existing fuel supply infrastructure. The cooling channel is integrated into the fuel supply line, combining the fuel delivery function with the cooling function in a single integrated component. This eliminates the need for separate cooling systems and reduces overall device complexity while effectively controlling piezo actuator temperature.
Solution Approach 2:
The cooling channel utilizes the kinetic energy and flow of the fuel itself to achieve cooling through adiabatic expansion and heat transfer to the channel walls. The fuel flow serves its own cooling function without requiring external cooling sources or additional active cooling mechanisms, thereby simplifying the system design.
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 effectively reduces the fuel temperature before it reaches critical components, ensuring reliable operation of the piezo actuators even at higher system pressures, simplifying the design and avoiding additional construction complexity and costs.
Implementation Method 1
The fuel can be cooled there before it gets into the immediate vicinity of temperature-sensitive components
Implementation Method 2
a magnetic actuator or a piezoelectric actuator
Data Source
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AI summary
The invention relates to a fuel injector (100), having a holding body (2) and a nozzle body (8) which is clamped axially against the holding body (2) by means of a nozzle clamping nut (9) with a restrictor plate (6) and a valve plate (4) being arranged in between, wherein a control valve (30) which can be switched between at least two switching positions is arranged in the valve plate (4) in a control-valve chamber (31), which control valve (30) can be actuated by means of an actuator which is arranged in an actuator chamber (23) of the holding body (2) and is preferably configured as a piezoelectric actuator, wherein fuel can flow through the actuator chamber (23) which is coupled hydraulically to a return bore (65) via a connection (73), and wherein a return quantity of the fuel which escapes from the control-valve chamber (31) during the switching of the control valve (30) and/or a return quantity of the fuel which escapes from the control-valve chamber (31) in the switching pauses of the control valve (30) can be discharged at least indirectly into the return bore (65) via a further connection. According to the invention, it is provided that the further connection has a flow path which comprises the annular chamber (5) between the nozzle clamping nut (9) and the nozzle body (8) and/or the valve plate (4) and/or the restrictor plate (6).