PTU Assembly with Cylinder for AWD Shift Actuation
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Solution Overview
Problem
Front wheel drive vehicles with four wheel drive capabilities face challenges in maximizing fuel efficiency, as existing power takeoff units (PTUs) require hydraulic actuation for quick actuation and shift times, and are not adaptable to various pressurized fluid sources, increasing costs and complexity.
Innovation Solution
A power takeoff unit design featuring an input shaft connected to the vehicle's transmission, an output shaft connected to the rear wheels, a shift collar, a shift fork, and a piston-cylinder assembly that allows for selective engagement and hydraulic actuation using multiple pressurized fluid sources, such as electric pumps or power steering pumps, to enable efficient four wheel drive operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a PTU is designed with hydraulic actuation for quick actuation and shift times, then the actuation speed is improved, but the device complexity and cost increase due to requiring specific hydraulic pump compatibility
Solution Approach 1:
The PTU is designed with a universal hydraulic interface that can accept pressurized fluid from multiple different pump sources (electric pumps, belt-driven pumps, transmission pumps, power steering pumps). This multi-functionality allows the same PTU design to be used across different vehicle platforms without requiring vehicle-specific hydraulic system integration, thus improving actuation speed while avoiding increased device complexity
2Adaptability or versatility
If a PTU is designed to be adaptable to various pressurized fluid sources, then the adaptability is improved, but the manufacturing complexity increases due to needing to accommodate multiple connection types
Solution Approach 1:
The PTU employs a standardized hydraulic port design that can interface with different pump types through universal quick-connect couplings or adaptive mounting brackets. This universal interface approach allows a single PTU manufacturing process to produce units compatible with electric pumps, belt-driven pumps, transmission pumps, and power steering pumps, thereby achieving high adaptability while maintaining manufacturing simplicity through standardization
Solution Approach 2:
The PTU incorporates adjustable or reconfigurable hydraulic connection interfaces that can be configured for different pump types without requiring different PTU units. This dynamic adaptability allows the same manufactured PTU to be installed on various vehicle platforms with different hydraulic sources, improving versatility while avoiding the need for multiple manufacturing lines
3Adaptability or versatility
If multiple PTU designs are created for different vehicle platforms, then the vehicle-specific compatibility is improved, but the manufacturing cost and inventory complexity increase
Solution Approach 1:
The PTU is designed as a universal component that can be installed on multiple vehicle platforms (different makes and models) through standardized mounting interfaces and adaptable hydraulic connections. This single universal design eliminates the need for maintaining separate inventory lines for different vehicle platforms, reducing manufacturing costs and simplifying supply chain management while achieving broad vehicle compatibility
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 enables quick and efficient shifting between two wheel and four wheel drive modes while being adaptable to various hydraulic power sources, enhancing fuel efficiency and reducing costs by minimizing the need for multiple PTU designs for different vehicles.
Implementation Method 1
A piston is slidably mounted within said cylinder. A headed fastener is provided with a shank extending through the shift fork main body bore. The fastener head engages the shift fork. The fastener's shank being threadably engaged with the piston to capture the shift fork with the piston.
Data Source
AI summary
A power takeoff unit for an automotive vehicle being a normally front-wheel drive vehicle that is convertible to all wheel drive. The takeoff unit includes an input shaft supported in a housing, the input shaft is torsionally connected with a transmission of said vehicle. An output shaft concentric with the input shaft is provided, the output shaft is torsionally connected with the rear wheels of the vehicle. A shift collar to selectively connect said input shaft with said output shaft is provided. A shift fork is provided to translate the shift collar, the shift fork having a main body with a bore. A cylinder is connected with the housing. A piston is slidably mounted within said cylinder. A headed fastener is provided with a shank extending through the shift fork main body bore. The fastener head engages the shift fork, the fastener's shank being threadably engaged with the piston to capture the shift fork with the piston.