Jet Propulsion Reverse Drive Speed Control
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Solution Overview
Problem
Marine vessels with jet propulsion devices face challenges in achieving a stable propulsive force during reverse drives due to air drawing, which causes fluctuations in engine load and propulsive force, especially during backward launching and in smaller-sized vessels.
Innovation Solution
A control unit is programmed to maintain the internal combustion engine within a predetermined speed range during reverse drives, adjusting the throttle opening degree to stabilize engine speed and prevent air drawing, while allowing for adjustments based on acceleration operation and engine speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the throttle opening degree is kept constant during reverse drive, then the engine speed control is simplified, but air drawing occurs causing engine load and propulsive force to fluctuate wildly
Solution Approach 1:
The patent applies dynamics by transitioning from a static throttle opening control to a dynamic engine speed control system. The control unit continuously monitors engine speed and adjusts the throttle opening degree in real-time to maintain the engine within a predetermined speed range during reverse drive, adapting to changing load conditions caused by air drawing phenomena.
Solution Approach 2:
The patent implements feedback control where the control unit receives feedback from the engine speed sensor and adjusts the throttle opening degree accordingly. This closed-loop control system ensures the engine speed remains within the predetermined range by comparing actual speed with target speed and making corrective adjustments, thereby stabilizing propulsive force despite air drawing fluctuations.
2Object-affected harmful factors
If the acceleration lever is pulled back to eliminate air drawing, then air intake is reduced, but engine load increases rapidly causing engine speed to drop
Solution Approach 1:
The control unit continuously monitors engine speed and throttle opening degree, using this feedback to prevent the harmful cycle of air drawing. By maintaining the engine within a predetermined speed range through real-time adjustments, the system avoids the conditions that cause air drawing while preventing excessive load increases that would drop engine speed.
Solution Approach 2:
The patent changes the control parameter from fixed throttle opening degree to dynamic engine speed maintenance. By controlling the engine to operate within a predetermined speed range rather than maintaining a constant throttle position, the system adapts to varying load conditions and eliminates air drawing without causing excessive engine load or speed drops.
3Speed
If the acceleration lever is increased to recover engine speed, then engine speed recovers, but air drawing occurs again causing load to fluctuate
Solution Approach 1:
The feedback control system continuously monitors both engine speed and throttle opening degree, preventing the oscillatory behavior of manually adjusting the acceleration lever. The control unit makes precise, incremental adjustments to maintain engine speed within the predetermined range, avoiding the conditions that trigger air drawing while recovering from load fluctuations.
Solution Approach 2:
The system transitions from static throttle control to dynamic speed-based control, allowing the engine to operate flexibly within a predetermined speed range. This dynamic approach accommodates temporary load variations without triggering air drawing, as the control unit continuously adapts the throttle opening to maintain stable operating conditions.
4Force
If water flow is directed forward during reverse drive, then reverse propulsive force is generated, but water reaches the intake port causing unstable water intake
Solution Approach 1:
The patent changes the control parameter from fixed throttle opening to dynamic engine speed maintenance within a predetermined range. This parameter change stabilizes the relationship between water flow generation and water intake, as the engine speed control ensures consistent impeller rotation and water flow characteristics, preventing water from reaching the intake port despite forward-directed water flow during reverse drive.
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 approach enables the acquisition of a stable propulsive force independently of load fluctuations, facilitating smoother reverse drive operations and reducing the difficulty of backward launching.
Implementation Method 1
Jet propulsion devices are arranged to be driven by an engine to take in water around the hull through an intake port and eject the water through an ejection port. The reactive force of the ejected water provides a propulsive force to the hull.
Implementation Method 2
The reverse bucket is arranged to reverse the direction of water (water flow) ejected through the ejection port forward with respect to the hull.
Implementation Method 3
a jet propulsion device arranged to be driven by an internal combustion engine
Data Source
AI summary
A marine vessel includes a hull and a jet propulsion device arranged to take in water through an intake port and eject the water through an ejection port rearward with respect to the hull. The ejection port is arranged posterior to the intake port. The marine vessel also includes a reversing member arranged to be movable between a forward drive position and a reverse drive position. The reversing member is arranged to, when placed at the reverse drive position, reverse the direction of the water ejected from the jet propulsion device forward with respect to the hull (in a direction capable of generating a propulsive force in the reverse drive direction). The marine vessel further includes an operation unit arranged to be operated by a marine vessel maneuvering operator to locate the reversing member at the forward drive position or the reverse drive position, and an internal combustion engine arranged to drive the jet propulsion device. The marine vessel also includes a control unit arranged and programmed to operate in a reverse drive mode in which when the reversing member is located at the reverse drive position by the operation unit, and such that the control unit controls the internal combustion engine to operate within a predetermined speed range.