Hydraulic Saildrive Clutch Lubrication for Silent Shifting
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Solution Overview
Problem
Existing sailboat propulsion systems with centrifugal pumps fail to supply lubricating oil to hydraulic wet multiplate clutches when the engine is stopped, leading to clutch engagement issues and increased noise during forward and reverse switching, particularly problematic for sailboats seeking to minimize engine room size and reduce cabin noise.
Innovation Solution
A hydraulic saildrive apparatus featuring a first hydraulic pump driven by the input shaft for supplying working and lubricating oil, and a second hydraulic pump driven by the output shaft for continuous lubricating oil supply, with a check valve system to prevent backflow and ensure lubrication during both powered and sail-only operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a centrifugal pump integrated into the propeller shaft or drive shaft is used, then lubricating oil can be supplied when the boat travels under power, but working oil is not supplied to the hydraulic wet multiplate clutch when the boat is stopped or traveling under sail
Solution Approach 1:
The pump system is divided into two independent pumps: a first pump (gear pump) driven by the input shaft for powered operation, and a second pump (centrifugal pump) driven by the propeller shaft for sail operation. Each pump is dedicated to specific operational conditions, ensuring reliable lubrication supply in both scenarios without requiring one pump to perform conflicting functions.
Solution Approach 2:
The dual-pump system creates a universal lubrication supply mechanism that functions across all operational modes of the saildrive apparatus - both under power and under sail. The system adapts to different operational conditions by activating the appropriate pump based on which shaft is rotating, making the lubrication system universally applicable regardless of propulsion method.
2Ease of operation
If a cone clutch operated by a mechanical shift mechanism is used, then the clutch can be engaged when the boat is stopped, but the clutch generates a large impact when switching between forward and reverse
Solution Approach 1:
The mechanical shift mechanism operating a cone clutch is replaced with a hydraulic wet multiplate clutch system controlled by hydraulic pressure from the first pump. This substitution eliminates the harsh mechanical engagement of the cone clutch, providing smoother clutch engagement and reducing impact noise during forward and reverse switching while maintaining the ability to engage the clutch when the boat is stopped.
3Area of stationary object
If the engine room size is reduced to enlarge the cabin area, then the cabin area increases, but noise from the engine room more easily transmits to the cabin area
Solution Approach 1:
The hydraulic wet multiplate clutch replaces the noisy mechanical cone clutch and shift mechanism, significantly reducing mechanical impact noise and operational sounds from the engine room. This substitution allows for a smaller engine room while maintaining lower noise levels, as the hydraulic system operates more quietly than mechanical linkages, thereby reducing noise transmission to the cabin area.
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 ensures consistent lubrication and smooth clutch engagement, reducing noise and mechanical stress, while allowing for a smaller engine room and improved cabin comfort by utilizing a hydraulic wet multiplate clutch that functions effectively under both power and sail conditions.
Implementation Method 1
a first hydraulic pump driven by the input shaft, for supplying working oil and lubricating oil to the clutch from an oil reservoir
Implementation Method 2
a second hydraulic pump that is driven by the output shaft, for supplying at least lubricating oil to the clutch from an oil reservoir
Implementation Method 3
a check valve provided in the second lubricating oil supply path, for preventing the flow of the lubricating oil from the first lubricating oil supply path into the direction of the second hydraulic pump
Data Source
AI summary
The subject invention provides a hydraulic saildrive apparatus comprising an upper unit 103 having an input shaft 1 connected to an engine 102 inside a boat, and a lower unit 104 having an output shaft 4 including a propeller shaft 2 and also having a lower portion protruding from the boat's bottom, wherein the upper unit 103 is provided with a hydraulic forward and reverse switching clutch 5 for transmitting the rotation direction of the input shaft 1 to the propeller shaft 2, the clutch 5 being capable of changing the rotation direction between forward and reverse relative to the input shaft 1.