PTU Hydraulic Pump Downstream Placement for FWD AWD
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Solution Overview
Problem
Front wheel drive vehicles with four wheel drive capabilities face challenges in maximizing fuel efficiency, as existing systems require auxiliary electric pumps for PTU actuation, which are costly and complicated by hydraulic line routing, and often rely on the transmission pump for hydraulic actuation.
Innovation Solution
A vehicle arrangement where the pump for the power takeoff unit (PTU) is placed downstream of the coupling/uncoupling mechanism, utilizing an accumulator to provide pressurized hydraulic fluid without an auxiliary electric pump or transmission pump, allowing for efficient four wheel drive operation without the need for additional hydraulic components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary electric pump is used for PTU hydraulic actuation, then the coupling and uncoupling of the prop shaft from the vehicle engine can occur when the vehicle has previously been in an uncoupled condition, but the system complexity and cost increase due to additional pump and hydraulic line routing
Solution Approach 1:
The patent extracts the hydraulic pump from the traditional transmission location and places it downstream of the PTU coupling mechanism. This extraction eliminates the need for complex hydraulic line routing between the transmission and PTU, while maintaining reliable hydraulic actuation for the PTU coupling and uncoupling operations
Solution Approach 2:
The hydraulic pump is designed to serve multiple functions: it provides hydraulic pressure for both the PTU coupling/uncoupling operations and the transmission operations. This multi-functionality eliminates the need for separate auxiliary electric pumps while maintaining all required actuation capabilities
2Power
If the transmission pump is used as the source of pressurized fluid for PTU actuation, then the hydraulic actuation can be provided, but the transmission pump capacity must be increased which increases cost and complexity
Solution Approach 1:
Instead of increasing the capacity of the transmission pump to provide hydraulic pressure for both transmission and PTU operations, the patent implements a smaller, dedicated pump located downstream of the PTU. This localized solution provides the necessary hydraulic power for PTU actuation without the complexity and cost of oversized transmission pump and associated hydraulic routing
3Power
If the pump is placed upstream of the PTU coupling mechanism, then hydraulic pressure can be provided for actuation, but the pump cannot be positioned optimally and requires auxiliary electric pump or transmission pump modification
Solution Approach 1:
Instead of placing the hydraulic pump upstream of the PTU coupling mechanism as traditionally done, the patent inverts the arrangement by placing the pump downstream of the coupling mechanism. This inversion allows the pump to be optimally positioned in the power flow path, eliminating the need for auxiliary pumps or transmission pump modifications while maintaining effective hydraulic actuation capability
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 solution eliminates the need for an auxiliary electric pump, reduces the complexity of hydraulic line routing, and enables efficient four wheel drive operation by using an accumulator to store sufficient hydraulic pressure for actuation, enhancing fuel efficiency and system simplicity.
Implementation Method 1
utilizing an accumulator to provide pressurized hydraulic fluid without an auxiliary electric pump or transmission pump
Data Source
AI summary
An arrangement of a vehicle is provided having normal transverse engine/transmission normal two-wheel drive operation which can be selectively placed into four-wheel drive operation wherein a pump which powers the coupling or uncoupling can be positioned downstream of a power takeoff unit without utilization of an electrically powered pump or transmission powered pump.