Transfer Case Distributor Gear with Stationary Power Take-Off
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Solution Overview
Problem
Existing transfer cases for commercial vehicles with coaxial drive and first output shafts and a distant second output shaft, along with a differential gear, face challenges in being compact while enabling a power take-off operation when stationary, as they often require increased length and inefficient engagement mechanisms.
Innovation Solution
A transfer case design with a coaxial input and first output shaft, a differential gear connected to the drive shaft, and a power take-off in permanent operative connection, featuring a planetary gear with a decoupling mechanism for the differential gear and a clutch for the power take-off flange, allowing operation when stationary without lengthening the transfer case, and incorporating a differential lock for efficient power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the power take-off is in permanent operative connection with the drive shaft, then the power take-off can be operated when the vehicle is stationary, but the transfer case length increases
Solution Approach 1:
The power take-off is nested within the existing coaxial structure of the drive shaft and differential gear. The power take-off shaft is arranged coaxially with the drive shaft, allowing it to be integrated into the existing space without increasing the overall length of the transfer case. This nested arrangement enables the power take-off to share the same axial space as other components.
Solution Approach 2:
Instead of extending the power take-off radially or axially which would increase length, the solution positions the power take-off shaft coaxially with the drive shaft, utilizing the radial dimension efficiently. The switching device controls engagement along the axial dimension while the power transmission occurs radially through the planetary gear structure, thereby avoiding length increase.
2Ease of operation
If the drive shaft of the differential gear is decoupled from the drive shaft of the transfer case, then the power take-off can operate when stationary, but the complexity of the switching device increases
Solution Approach 1:
The switching device is designed to perform multiple functions: it controls both the decoupling of the differential gear drive shaft from the transfer case drive shaft, and the engagement/disengagement of the power take-off output flange. This multi-functionality reduces the need for separate switching mechanisms and simplifies the overall control structure despite the complex operational requirements.
Solution Approach 2:
The switching device merges the control functions for the differential lock and the power take-off engagement into a single mechanism. The first switching element controls the connection between the drive shaft and the planetary gear input shaft, while the second switching element controls the power take-off output flange engagement, both integrated within one switching device structure.
3Reliability
If a differential lock is arranged to connect the sun gear to the planet carrier, then the differential can be locked, but the switching device arrangement becomes more complex
Solution Approach 1:
The differential lock mechanism is integrated with the existing planetary gear structure, utilizing the sun gear and planet carrier that are already part of the power take-off mechanism. The same planetary gear components serve both the power take-off function and the differential lock function, eliminating the need for separate locking mechanisms and reducing overall complexity.
Data Source
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AI summary
A transfer case has a differential gear (8) arranged coaxially to the drive shaft (1), which drives a first output shaft (11) arranged coaxially to the drive shaft (1) and a second output shaft (14) arranged at a distance from the drive shaft (1), and a secondary output shaft which is driven via a spur gear (2).