Transfer Unit for Motor Vehicle Power Distribution
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Solution Overview
Problem
Existing power transmission devices for four-wheel-drive vehicles cannot effectively transmit power from a motor to drive wheels via a planetary gear device when one rotational element is fixed to a fixing member, limiting their functionality in switching between different driving states.
Innovation Solution
A transfer system incorporating an input shaft, a motor, first and second planetary gear devices, and a connection switching unit that allows switching between direct coupling, speed-changing, and distribution states, enabling power transmission to both main and auxiliary drive wheels while allowing differential motions and speed changes, thereby overcoming the limitation of fixed rotational elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If one rotational element is fixed to a fixing member in the planetary gear device, then the structure is simplified and manufacturing is easier, but power cannot be transmitted from the motor to drive wheels effectively
Solution Approach 1:
The patent applies the dynamics principle by making the fixing member selectively engageable and disengageable from the rotational element. The fixing member can be positioned in a first position to fix the rotational element, and a second position to release it, allowing the system to dynamically switch between different operational modes. This enables the planetary gear device to function as both a transmission unit (when fixed) and a distribution unit (when released), resolving the contradiction between manufacturing simplicity and power transmission capability.
2Speed
If the planetary gear device functions as a transmission unit with a fixed rotational element, then speed changing is achieved, but the system cannot switch between different driving states effectively
Solution Approach 1:
The fixing member is designed to be movable between a first position (engaging with the rotational element) and a second position (disengaged from the rotational element). When engaged, the planetary gear device operates as a transmission unit with speed changing capability. When disengaged, it operates as a distribution unit, enabling the system to switch between different driving states (two-wheel drive and four-wheel drive), thereby resolving the contradiction between speed changing capability and adaptability.
Solution Approach 2:
The planetary gear device is designed to perform multiple functions: it can operate as a transmission unit (with speed changing) when the fixing member is engaged, and as a distribution unit (without speed changing) when the fixing member is disengaged. This multi-functionality allows the system to adapt to different driving conditions, resolving the contradiction between specialized speed changing capability and general adaptability.
3Power
If the input shaft is directly coupled to the output shaft, then power transmission is efficient, but the system lacks speed changing and distribution capabilities
Solution Approach 1:
The power transmission path is segmented into multiple possible routes: a direct coupling path (input shaft directly to output shaft) for efficient power transmission, and a planetary gear path (input shaft to planetary gear device to output shaft) for speed changing and distribution. The switching mechanism allows selection between these segments, enabling the system to choose the most appropriate path based on driving conditions, thereby resolving the contradiction between power transmission efficiency and adaptability.
Data Source
AI summary
A transfer includes: an input shaft; a motor; first and second output shafts; first and second planetary gear devices; an input switching unit; a transmission switching unit; and a distribution switching unit. Further, connection states of the input shaft, the first and the second planetary gear devices, the first and the second output shafts can be switched to a plurality of modes including first, second, and third modes by the input switching unit, the transmission switching unit, and the distribution switching unit.