Pulsed Detonation Engine Variable Stiffness Fuel Spring
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Solution Overview
Problem
Pulsed detonation engines face challenges in controlling the spring's stiffness to balance movement speed and braking forces, leading to inefficiencies in operating frequency and cycle time due to antagonistic constraints during the compression and propulsion phases.
Innovation Solution
The engine utilizes a transfer chamber with variable volume, filled with fuel, as elastic return means, allowing for controlled propulsion and braking by compressing fuel to slow down the movable bottom and apply maximum force, reducing mechanical elements and enhancing robustness, and incorporates an auxiliary compression spring for additional support when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the spring is made flexible (low stiffness) during the outward stroke, then the movement speed of the movable bottom is improved, but the braking force at the end of travel is insufficient
Solution Approach 1:
The spring stiffness is made variable through the progressive closure of perforations in the firewall during the outward stroke. This dynamic adjustment allows the spring to transition from a softer state (when perforations are open) to a stiffer state (as perforations close), resolving the contradiction between needing low stiffness for speed and high stiffness for braking force.
Solution Approach 2:
The effective stiffness parameter of the spring is changed during operation by controlling the closure of perforations. As the movable bottom moves outward, the firewall rotates to close perforations sequentially, changing the spring's effective stiffness from low to high, thereby providing both fast movement and strong braking force.
2Force
If the spring is made stiff (high stiffness) during the return stroke, then the acceleration force is maximized, but the movement speed of the movable bottom is limited
Solution Approach 1:
The spring stiffness is dynamically adjusted during the return stroke by the progressive opening of perforations in the firewall. This allows the spring to provide maximum acceleration force initially, then gradually reduce stiffness as the movable bottom approaches the forward position, maintaining high speed throughout the return stroke.
Solution Approach 2:
The effective stiffness parameter is changed during the return stroke by controlling the opening of perforations. The spring transitions from high stiffness (for acceleration) to low stiffness (for maintaining speed), resolving the contradiction between needing high force for acceleration and high speed for overall performance.
3Device complexity
If a single spring is used for both propulsion and braking, then the device complexity is reduced, but the ability to optimize both phases is compromised
Solution Approach 1:
The single spring is segmented functionally through the perforated firewall structure. Different sections of the spring act through different perforations at different times, allowing independent optimization of propulsion and braking phases while using a single physical spring component.
Solution Approach 2:
The single spring performs multiple functions (propulsion and braking) at different times during the operating cycle. The perforated firewall enables this multi-functionality by controlling which sections of the spring are active during each phase, improving productivity without increasing component count.
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 stabilizes speed variations and vibrations, improves integration, and reduces operating cycle time by leveraging fuel pressure for efficient propulsion and braking, while minimizing mechanical components, thus enhancing the engine's performance and robustness.
Implementation Method 1
said elastic return means consist, at least in part, of the fuel contained in said transfer chamber. Thus, the compression of the fuel contained in the transfer chamber by the movable bottom allows the elastic return means to gradually slow down the stroke of the latter during its movement from the second position to the first
Implementation Method 2
the compression of the fuel contained in the transfer chamber by the movable bottom allows the elastic return means to gradually slow down the stroke of the latter during its movement from the second position to the first
Implementation Method 3
said elastic return means further comprise at least one auxiliary compression spring capable of helping to propel said mobile bottom from the first position to the second and to brake the latter at the end of movement from the second position to the first
Data Source
Figure 1A~1B
Figure 1C~2
AI summary
The engine (I) has a fuel supplying unit for supplying fuel to a combustion chamber (7) from a flame tube (2), and including a transferring chamber (9) with variable volume delimited by a lateral wall (6) of the tube, a transversal movable base (3) and a transversal support (5). A cylindrical fuel transferring unit (10) transfers the fuel from a fuel tank (4) towards the transferring chamber, and fuel injectors (11) inject the fuel in the combustion chamber from the transferring chamber. Elastic returning units e.g. springs, are constituted by the fuel contained in the transferring chamber. The fuel is in the form of gaseous or liquid.