Transfer Case Shifting Elements for Loaded Ratio Switching
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Solution Overview
Problem
Existing transfer cases for motor vehicle drive trains lack the ability to switch between different gear ratios with high shifting comfort, particularly in off-road conditions where quick and loaded ratio changes are necessary.
Innovation Solution
A transfer case design incorporating a transmission device with two shiftable shifting elements, allowing for seamless switching between road and off-road gear ratios, with the option for additional shifting elements to provide further ratios, and a distributor device connected to multiple drive axles for efficient power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If form-fitting shifting elements with tooth engagements are used, then reliable power transmission is achieved, but shifting comfort and speed are reduced
Solution Approach 1:
A synchronizer mechanism is introduced as an intermediary component between the shifting element and the gear ratio change. The synchronizer includes friction elements that gradually equalize the rotational speeds of engaging components before final tooth engagement, enabling smooth shifting under load while maintaining reliable power transmission.
Solution Approach 2:
A hydraulic actuating system is employed to provide controlled force for engaging the shifting elements. The hydraulic system enables precise, load-bearing shifts by gradually applying pressure to move the synchronizer and shifting elements, improving shifting comfort and speed while maintaining transmission reliability.
2Adaptability or versatility
If multiple shifting elements are added to provide additional gear ratios, then adaptability is improved, but device complexity increases
Solution Approach 1:
The transmission device is designed with a modular architecture where each shifting element follows a standardized pattern using identical synchronizer mechanisms and hydraulic actuation systems. This universal design allows multiple gear ratios to be added while reusing proven components, thereby increasing adaptability without proportionally increasing overall system complexity.
Solution Approach 2:
The shifting elements and synchronizer mechanisms are arranged in a compact, nested configuration within the transmission housing. Multiple shifting stages are integrated in a space-efficient manner, allowing additional gear ratios to be incorporated without proportionally increasing the overall size and complexity of the transmission device.
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 comfortable operation by allowing quick and loaded switching between transmission ratios, enhancing the vehicle's ability to adapt to different operating states with high comfort and efficiency.
Implementation Method 1
a transmission device (17), in that a power flow can be supplied via the transmission device (17) with a first transmission ratio by actuating the first shifting element (27) and with a second transmission ratio by actuating the second switching element (28)
Data Source
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AI summary
The invention relates to a transfer case (8) for a motor vehicle powertrain (2), comprising a transfer unit (18) and a transmission unit (17) which has a first switching element (27) and a second switching element (28). A power flow from a transmission input (13) of the transfer case (8) can be supplied to the transfer unit (18) on the input side via the transmission unit by actuating the first switching element (27) with a first transmission ratio and by actuating the second switching element (28) with a second transmission ratio. The transfer unit (18) is connected on the output side to several transmission outputs (10, 11) which are each provided in the motor vehicle powertrain (2) for connection to a drive axle (3, 4).In order to achieve a high level of shifting comfort in this transfer case (8), the first shifting element (27) and the second shifting element (28) are designed as load-shiftable shifting elements.