PTU Driveline Actuator Powered by Synchronization Event
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Solution Overview
Problem
Existing disconnectable all-wheel drive vehicle drivelines face inefficiencies in transitioning between two-wheel drive and all-wheel drive modes, particularly in maximizing fuel economy and seamless power transmission.
Innovation Solution
A drivetrain configuration incorporating a primary driveline, a power take-off unit (PTU), a secondary driveline, a hydraulic pump, and a hydraulic actuator, with axially slidable coupling members and multi-plate friction couplings, allows for controlled power transmission and synchronization between drivelines, enabling efficient mode switching through hydraulic fluid pressurization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the actuator is operated continuously to enable rapid mode switching, then the responsiveness and seamlessness of mode transition is improved, but the energy consumption increases
Solution Approach 1:
The hydraulic pump is activated only periodically when mode transition is required, rather than continuously. The pump generates hydraulic pressure on-demand to actuate the coupling member, enabling rapid mode switching while minimizing energy consumption during steady-state operation in either two-wheel drive or all-wheel drive mode.
Solution Approach 2:
The system uses the rotational energy already present in the driveline (from the engine or motor) to drive the hydraulic pump during mode transitions, rather than requiring an external power source. The pump is driven by the driveline itself, converting existing mechanical energy into hydraulic pressure for actuation.
2Speed
If the coupling member is designed for rapid actuation, then the mode transition responsiveness is improved, but the mechanical complexity increases
Solution Approach 1:
The system employs a hydraulic actuation mechanism where a pump generates hydraulic pressure that acts on a piston or cylinder to move the coupling member axially. This hydraulic system enables rapid and controlled actuation of the coupling member without requiring complex mechanical linkages, springs, or cam mechanisms that would increase mechanical complexity.
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
Enables efficient operation in both two-wheel drive and all-wheel drive modes by ensuring seamless power transmission and maximizing fuel economy by optimizing power distribution and reducing energy loss during mode transitions.
Implementation Method 1
a hydraulic pump having a pump stator and a pump rotor that is rotatable relative to the pump stator
Implementation Method 2
The actuator is coupled to the PTU and has a hydraulic cylinder and an actuator output member that is driven by the hydraulic cylinder
Implementation Method 3
The second coupling is a multi-plate friction coupling that is operable in a third coupling mode, in which the second input member is decoupled from at least one of the pair of second driveline output members
Data Source
AI summary
A disconnectable all-wheel drive vehicle driveline having a primary driveline, a power take-off unit (PTU), a secondary driveline, a hydraulic pump and a driveline actuator. The PTU has a PTU input member, which is driven by the primary driveline, a PTU output member and a first coupling that selectively couples the PTU input and output members. The secondary driveline includes a second coupling that selectively inhibits power transmission through the secondary driveline. The hydraulic pump is configured to operate the first coupling but is powered by a synchronization event in which the second coupling is engaged so as to back drive the PTU output member.