Retractable Pump Jet Drive for Low Noise Watercraft Propulsion
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Solution Overview
Problem
Pump jet drives for watercraft suffer from noise and hydrodynamic issues due to permanently open inlet and outlet nozzle openings, which are undesirable in applications like surface ships with sonar devices or submarines, limiting their adoption.
Innovation Solution
A pump jet drive design with a rotatable housing, where the inlet and outlet nozzles are completely hidden within the hull in the retracted position and extend only when in use, minimizing noise and hydrodynamic interference, and allowing for adjustable propulsion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If pump jet propulsion systems use permanently open inlet and outlet nozzle openings, then propulsion function is achieved, but noise and hydrodynamic interference increase
Solution Approach 1:
The inlet and outlet nozzles are designed to be movable between retracted and extended positions. In the retracted position, the nozzles are hidden within the hull to minimize noise and hydrodynamic interference. When propulsion is needed, the nozzles extend to enable water intake and thrust generation. This dynamic positioning allows the system to switch between low-noise mode and propulsion mode.
Solution Approach 2:
The propulsion system is divided into separable components: the hull with integrated nozzles and the movable inlet/outlet openings. The nozzles can be independently controlled to extend or retract, allowing the system to maintain hull integrity while enabling propulsion functionality when needed.
2Productivity
If inlet and outlet nozzles are permanently open, then propulsion is enabled, but drag and sonar echo increase in rest position
Solution Approach 1:
The nozzle openings dynamically adjust their position based on operational requirements. During rest or cruising without propulsion needs, the nozzles are retracted into the hull to maintain a smooth outer surface, minimizing drag and reducing sonar echo signatures. When propulsion is activated, the nozzles extend to enable water flow for thrust generation.
3Object-generated harmful factors
If nozzles are retracted into hull, then noise and drag are minimized, but propulsion function is lost
Solution Approach 1:
The system employs movable nozzles that can extend from the hull when propulsion power is required and retract when not needed. This dynamic extension allows the pump jet system to generate the necessary propulsion power by enabling water intake through the inlet nozzle and exhaust through the outlet nozzle, while maintaining low noise and drag characteristics during retraction.
4Shape
If cover plate closes opening in rest position, then flow along hull is improved, but access to drive is blocked
Solution Approach 1:
The drive system is segmented into the fixed hull structure with integrated nozzles and the movable nozzle components. The nozzles are designed to extend through the hull opening without requiring a separate cover plate, as the nozzle structure itself provides the necessary sealing and flow management when retracted, while allowing access when extended for maintenance.
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 design minimizes driving resistance and noise in the retracted position, reduces sonar echoes, and provides effective propulsion when extended, making it suitable for applications requiring low noise and minimal hydrodynamic interference.
Implementation Method 1
a propeller arranged between the inlet channel and the outlet nozzle and designed as an impeller
Implementation Method 2
the water surrounding the hull of the watercraft is sucked in via the inlet channel by a propeller designed as an impeller and arranged within the hull, accelerated
Implementation Method 3
after possibly several deflections of the flow direction, expelled as a thrust jet via a pivoting outlet nozzle in order to generate the desired propulsion and to steer the watercraft
Implementation Method 4
expelled as a thrust jet via a pivoting outlet nozzle in order to generate the desired propulsion
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a drive (1) of a watercraft (2) which is movable in an opening (21) of a hull (20) of the watercraft (2) between a retracted rest position and an extended working position, wherein the drive (1) has a propeller with an associated drive motor (11) and a cover plate (17) which covers the shaft (21) in the rest position, wherein the drive (1) is designed as a pump jet and has a housing (10) with at least one inlet channel (14) and at least one outlet nozzle (15) communicating therewith and a propeller arranged between the at least one inlet channel (14) and the at least one outlet nozzle (15) and designed as an impeller (13), by means of which water is sucked in via the inlet channel (14), accelerated and, after at least a simple deflection of the flow direction, can be expelled as a thrust jet via the outlet nozzle (15),wherein the housing (10) is rotatable about the control axis (10) by means of a control drive and wherein the drive (1) in the extended working position is extendable from the opening (21) to such an extent that the at least one inlet channel (14) and the at least one outlet nozzle (15) protrude beyond the region of the fuselage (20) delimiting the opening (21).