Hydraulic Transfer Case Dry Sump On-Demand Lubrication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Hydraulically actuated transfer cases are inefficient due to wet sump designs causing energy losses from components splashing in the oil sump and continuously driven lube pumps.
Innovation Solution
A high-efficiency hydraulic transfer case design featuring a dry sump configuration and an on-demand electric lube pump that stores hydraulic energy in an accumulator for clutch actuation and range shifting, using solenoid valves to direct fluid flow efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wet sump design is used with continuously driven lube pump, then lubrication is continuously provided, but energy losses occur due to components splashing in the oil sump and continuous pump operation
Solution Approach 1:
The patent implements an on-demand lube pump that operates periodically rather than continuously. The pump is activated only when lubrication is required, such as during clutch engagement or range shifting operations. This periodic operation eliminates energy losses associated with continuous pump operation while still providing necessary lubrication at appropriate times.
Solution Approach 2:
The patent extracts the lube pump from the traditional wet sump configuration and repositions it as an on-demand electric pump. This extraction allows the pump to be controlled independently and operated only when needed, rather than running continuously as part of the wet sump system. The pump is positioned to deliver lubrication directly to specific components rather than relying on splash lubrication from a common sump.
2Reliability
If a continuously driven lube pump is used, then lubrication is always available, but power consumption increases due to continuous operation
Solution Approach 1:
The on-demand lube pump operates periodically based on system requirements rather than continuously. It is activated during specific events such as clutch engagement, range shifting, or when lubrication pressure drops below a threshold. This periodic operation significantly reduces power consumption while maintaining adequate lubrication availability when needed.
Solution Approach 2:
The lubrication system incorporates sensors and control logic that automatically activate the pump when lubrication is required. The system monitors its own lubrication status and triggers pump operation autonomously based on detected needs, eliminating the requirement for continuous operation while ensuring lubrication is available when required.
3Reliability
If a wet sump design is used, then lubrication is provided through splash lubrication, but energy is lost due to components splashing in the oil sump
Solution Approach 1:
The patent extracts the lube pump from the wet sump configuration and repositions it as an on-demand electric pump. This extraction allows the pump to be controlled independently and operated only when needed, rather than running continuously as part of the wet sump system. The pump is positioned to deliver lubrication directly to specific components rather than relying on splash lubrication from a common sump.
Solution Approach 2:
The on-demand lube pump acts as an intermediary device that delivers lubrication directly to specific components through controlled fluid delivery. Instead of relying on indirect splash lubrication from a wet sump, the pump provides direct, targeted lubrication to clutch packs, range shift mechanisms, and other moving components, eliminating energy losses from unnecessary splashing.
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 design increases efficiency and reduces power consumption by eliminating energy losses from component splashing and continuous lube pump operation, allowing for more motor 'off time and improved lubrication control.
Implementation Method 1
An on-demand lube pump can be provided for supplying a fluid under pressure
Implementation Method 2
An accumulator can be selectively supplied with fluid under pressure from the on-demand lube pump
Implementation Method 3
A first valve can selectively direct fluid under pressure from the on-demand lube pump to the lubrication system when in a first position, and to the accumulator when in a second position
Implementation Method 4
a hydraulically actuated friction clutch assembly
Implementation Method 5
A lubrication system selectively supplied with fluid under pressure from the on-demand lube pump can be provided for lubricating the friction clutch assembly
Data Source
AI summary
A power transfer case transfers drive torque from the input member to the output member. The power transfer case includes a lubrication system, a hydraulically actuated friction clutch assembly, and a hydraulically actuated range shift assembly. An on-demand electric lube pump can supply a fluid under pressure. An accumulator is selectively supplied with fluid under pressure from the on-demand lube pump. A first valve selectively directs fluid under pressure from the on-demand lube pump to the lubrication system when in the first position and to the accumulator when in a second position. A second valve selectively directs fluid under pressure from the accumulator to the range shift assembly when in a first position, to the friction clutch assembly when in a second position, and isolates the accumulator from the range shift assembly and the friction clutch assembly when in a third position.