Differential-Free Secondary Axle Drive Unit for Power Loss Reduction
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Solution Overview
Problem
Existing drive trains with switchable secondary axles suffer from increased complexity, weight, and fuel consumption due to additional components required for speed synchronization and power transmission, leading to significant power losses when the secondary axle is decoupled.
Innovation Solution
A differential-free secondary axle drive unit with side shaft clutches that allows for automatic engagement and disengagement of the secondary axle during driving, reducing the number of components and power losses by using a thrust bearing and corrugated spring for speed compensation, and demand-controlled oiling of disk packs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a switchable secondary axle is integrated into the drive train, then the vehicle can distribute drive power to all wheels in certain operating situations, but the drive train becomes significantly more complex and heavier
Solution Approach 1:
The patent extracts the differential function from the traditional secondary axle drive train and integrates it into the primary drive train. By removing the separate differential unit and intermediate shaft, the patent reduces device complexity while maintaining the capability to distribute drive power to the secondary axle when needed.
Solution Approach 2:
The patent merges the differential function with the primary drive train components. The clutch mechanism is integrated directly into the primary drive train, allowing it to perform both primary drive transmission and secondary axle power distribution functions, thereby reducing overall system complexity.
2Adaptability or versatility
If additional components like longitudinal compensation and transverse differential are added to handle speed differences, then the secondary axle can operate at different speeds, but the drive train becomes even more complex and expensive
Solution Approach 1:
The patent makes the clutch mechanism multi-functional by enabling it to perform speed synchronization, power transmission, and speed difference compensation all through a single device. This eliminates the need for separate longitudinal compensation and transverse differential components.
Solution Approach 2:
The patent removes the traditional longitudinal compensation mechanism and transverse differential from the drive train. Instead, these functions are absorbed into the clutch mechanism's operation, significantly reducing the number of components required.
3Device complexity
If the secondary axle drive train components remain connected even when decoupled, then the system remains simple, but significant power losses occur due to friction and rotating masses
Solution Approach 1:
The patent implements a dynamic connection system where the secondary axle drive train components are automatically decoupled when the secondary axle is not in use. The clutch mechanism dynamically adjusts the connection state based on operating conditions, completely disconnecting the secondary drive train components to eliminate friction losses and reduce the acceleration of rotating masses.
4Device complexity
If manual switching mechanisms are used for the secondary axle, then the system can be simpler, but the switching process becomes cumbersome and requires vehicle reversal
Solution Approach 1:
The patent implements a self-synchronizing clutch mechanism that automatically performs the switching operation without driver intervention. The system self-regulates the engagement and disengagement of the secondary axle based on operating conditions, eliminating the need for manual switching and vehicle reversal while maintaining mechanical simplicity.
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 minimizes power losses and weight, enabling the secondary axle to be switched on automatically at higher speeds, reducing fuel consumption and enhancing usability, while maintaining transverse and longitudinal compensation without the need for additional differentials.
Implementation Method 1
the at least one side shaft clutch has a friction-locking friction plate clutch with inner discs and outer discs
Implementation Method 2
A thrust bearing is arranged between the disk set and the pressure piston, which ensures the speed equalization between the stationary pressure piston and the rotating disk set
Implementation Method 3
a corrugated spring is supported between the outer disk carrier and a Z-disk of the thrust bearing
Implementation Method 4
demand-controlled oiling of disk packs
Data Source
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AI summary
In order to minimize power loss when the secondary axle 2 is switched off and the secondary drive train is deactivated, and to deactivate as many components as possible in a drive train comprising a permanently driven primary axle 1 and a secondary axle 2 that can be switched on to it, as well as a deactivatable secondary drive train, an axle drive unit 9 is provided in which a wave spring 25 is supported between a thrust bearing 24 which ensures speed compensation to a rotating multi-plate pack and an outer multi-plate carrier 8 of a multi-plate clutch.