Pumpless Transfer Case Lubrication for Disconnect Axles
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Solution Overview
Problem
In four-wheel drive vehicles with disconnectable secondary drivelines, there is a need for a pumpless lubrication system to provide lubrication to the transfer case components, including the mode clutch and bearings, when the vehicle is in 2WD mode, as traditional pumps are not operational during this mode.
Innovation Solution
A transfer case design featuring an elevated primary lubricant sump and a secondary lubricant sump, with a pumpless lubrication system that utilizes the rotation of the transfer assembly to convey lubricant from the secondary sump to the primary sump, ensuring continuous lubrication of the transfer clutch and other rotary components without the need for a lube pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a pumpless lubrication system is used to reduce energy consumption and parasitic drag, then fuel economy is improved, but the ability to provide continuous lubrication when the transfer assembly is not rotating is worsened
Solution Approach 1:
The system pre-positions lubricant in an elevated sump above the transfer clutch components. This preliminary placement of lubricant ensures that when the transfer assembly rotates, the lubricant is already in position to be flung onto the clutch plates and bearings, eliminating the need for a pump while maintaining continuous lubrication.
Solution Approach 2:
The lubrication system operates periodically through the rotation of the transfer assembly. As the transfer assembly rotates, it periodically flings lubricant from the elevated sump onto the clutch plates and bearings. This periodic action is sufficient to maintain lubrication without requiring continuous pump operation, thus improving fuel economy while ensuring reliability.
2Productivity
If the primary lubricant sump is elevated above the secondary sump, then lubricant can be effectively distributed to the transfer clutch and bearings through rotation, but the structural complexity of the lubrication system increases
Solution Approach 1:
The system transitions from a horizontal or low-positioned sump configuration to a vertical/elevated sump configuration. By positioning the primary lubricant sump above the transfer clutch and secondary sump, the system utilizes the vertical dimension to enable effective lubricant distribution through gravitational and centrifugal forces during rotation, improving productivity while accepting increased structural complexity.
3Reliability
If a shaft-driven lube pump is used to convey lubricant from the sump to the mainshaft, then reliable lubrication is ensured, but energy consumption increases and parasitic drag is introduced
Solution Approach 1:
The system extracts and removes the shaft-driven lube pump from the lubrication system. Instead of using mechanical pumping, the design relies on the elevated sump position and the rotational motion of the transfer assembly to naturally convey lubricant to the clutch plates and bearings. This extraction eliminates the parasitic drag and energy consumption associated with pump operation while maintaining lubrication reliability.
Solution Approach 2:
The lubrication system becomes self-service through the rotation of the transfer assembly. The rotating transfer assembly automatically flings lubricant from the elevated sump onto the clutch plates and bearings without requiring external pumping. This self-service mechanism eliminates energy consumption and parasitic drag while ensuring reliable lubrication distribution.
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 configuration ensures effective lubrication of the transfer case components during both 4WD and 2WD modes, enhancing the durability and efficiency of the drivetrain by maintaining lubrication without the energy consumption of a pump, thus improving fuel economy and reducing parasitic drag.
Implementation Method 1
a pumpless lubrication system that utilizes the rotation of the transfer assembly to convey lubricant from the secondary sump to the primary sump
Data Source
AI summary
A transfer case for a four-wheel drive vehicle having a disconnectable secondary axle assembly. The transfer case is configured to include a pumpless lubrication sump maintained in relation to a mainshaft for lubricating rotary components surrounding the mainshaft.