Hydraulic Control for Ship Transmission Lubrication
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Solution Overview
Problem
Hydraulic control systems for marine transmissions face challenges in ensuring lubricant supply when the engine is at a standstill and the output shaft is rotating, as the primary pump is not driven, leading to inadequate lubrication of transmission components during towing or stationary conditions.
Innovation Solution
A hydraulic control system incorporating a lubricant quantity-controlled control valve, also known as a towing valve, is connected in parallel to the primary pump, ensuring lubricant supply even when the primary pump is insufficiently driven. This control valve is activated based on pressure and flow rate, allowing lubricant delivery below the system pressure and closing when the primary pump reaches its minimum delivery rate, thereby bypassing the towing valve and utilizing the system pressure valve for lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary pump is used to supply lubricant during normal operation, then the system pressure valve can maintain predetermined system pressure, but no oil is pumped when the drive shaft is not rotating (engine switched off)
Solution Approach 1:
The system employs two pumps with different drive sources: the primary pump driven by the drive shaft for normal operation, and the tug pump driven by the output shaft for towing/stationary conditions. This multi-functionality ensures lubricant supply across all operating scenarios, resolving the contradiction between reliability during normal operation and adaptability to stationary conditions.
Solution Approach 2:
The control valve acts as an intermediary between the two pumps and the lubricant circuit. It automatically selects which pump supplies lubricant based on operating conditions, enabling seamless transition between primary pump and tug pump operation, thus ensuring continuous reliable lubrication while adapting to different operational states.
2Reliability
If the tug pump is combined with a pressure relief valve that opens at pressure below system pressure, then the tug pump is protected from generating system pressure, but the lubricant is directed into the transmission oil sump instead of supplying the lubricant circuit
Solution Approach 1:
The control valve uses pressure feedback to determine pump operation status. When the primary pump is insufficiently driven and pressure drops below a threshold, the control valve opens to allow the tug pump to supply lubricant. When the primary pump restores sufficient pressure, the control valve closes, directing flow through the system pressure valve. This feedback mechanism ensures the tug pump operates only when needed while maintaining proper lubricant delivery.
Solution Approach 2:
The system dynamically switches between tug pump and primary pump operation based on real-time pressure conditions. The control valve adjusts its state continuously according to drive shaft rotation status and primary pump performance, enabling the tug pump to provide lubrication during insufficient operation while automatically transitioning to primary pump control when conditions normalize.
3Reliability
If an additional control valve is added to ensure lubricant supply during towing operation, then lubrication is ensured when the primary pump is insufficiently driven, but the device complexity increases
Solution Approach 1:
The control valve is designed to automatically regulate lubricant flow based on pressure and flow rate conditions without external intervention. It self-adjusts to open or close depending on whether the primary pump is sufficiently driven, eliminating the need for additional control systems or manual operation. This self-service capability ensures reliable lubricant supply during towing while avoiding the complexity of externally controlled switching mechanisms.
4Ease of operation
If the control valve is controlled as a function of pressure or flow rate to open below minimum flow rate, then the control valve automatically opens when the primary pump is not driven sufficiently, but the control system becomes more complex
Solution Approach 1:
The control valve utilizes hydraulic principles where pressure differential and flow rate through an orifice automatically control valve opening. The tug pump's output pressure, modulated by the orifice, directly actuates the control valve piston. This purely hydraulic control mechanism eliminates the need for electronic sensors, actuators, or complex control circuits, achieving automatic operation based on pressure/flow conditions while maintaining mechanical simplicity.
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 continuous lubrication of marine gear components during engine standstill and towing operations, preventing damage and reducing costs by eliminating the need for additional filters and coolers, while maintaining a compact and cost-effective configuration.
Implementation Method 1
a control valve (19) for supplying lubricant when the output shaft is rotating, wherein the control valve (19) opens below a predetermined minimum flow rate of the primary pump (2) for lubricant supply
Implementation Method 2
the control valve can be spring-loaded and designed with an orifice at the outlet or the like. As the flow rate increases, the orifice achieves the corresponding closing pressure at which the control valve is closed
Data Source
Figure 1
Figure 2~4
AI summary
The control has a system pressure valve (5) for adjusting predetermined system pressure and for lubricant supply in a driving operation. The pressure valve is connected with a primary pump (2) that is driven by a drive shaft. A tow drive pump (13) is provided for pressurizing agent supply in a tow drive operation, and is connected parallel to the primary pump. The drive pump is driven by an output shaft. A control valve (19) controls lubricant amount and supplies lubricant during rotation of the output shaft. The control valve is designed as a tow drive valve.