Compact Axle Unit Radial Planetary Gear Integration
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Solution Overview
Problem
Existing hybrid drive train systems with two-speed transmissions are not compact enough for integration into purely electric motor-driven vehicles, as they require significant installation space and cannot achieve optimal transmission ratios suitable for electric motor-driven vehicles, especially under load conditions.
Innovation Solution
A compact axle drive unit design with a power-shiftable two-speed transmission where the planetary gears are integrated radially inside the outer wheel, allowing for a flat and compact axial layout, and featuring a passive or active blocking device to enable efficient torque management and gear ratio adjustments, including a differential unit integrated within the axle drive housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a two-speed transmission is integrated into an axle drive unit for a purely electric motor-driven vehicle, then the transmission ratio can be optimized for electric motor performance, but the installation space requirement increases
Solution Approach 1:
The planetary gears are integrated radially inside the outer wheel, with the planet gears nested within the radial space of the outer wheel structure. This nesting arrangement allows the transmission components to occupy the same radial envelope, significantly reducing the axial space requirement and enabling compact integration into the axle drive unit.
Solution Approach 2:
The patent transitions from a conventional axial layout to a radial integration approach, where the planetary gears are positioned radially inside the outer wheel rather than axially adjacent to it. This dimensional reorganization allows the transmission system to achieve optimal gear ratios while maintaining a compact axial footprint suitable for electric vehicle applications.
2Adaptability or versatility
If a three-shaft offset is used to direct drive power to wheel shafts, then the transmission can accommodate hybrid drive train requirements, but the device complexity and installation space increase
Solution Approach 1:
The axle drive unit is designed with a universal structure that can accommodate both purely electric motor-driven applications and hybrid drive train configurations. The integrated planetary gear system and differential unit can handle various drive power sources and transmission requirements, making the same basic design adaptable to different vehicle architectures without requiring completely separate systems.
Solution Approach 2:
The differential unit is integrated within the axle drive housing, merging the functions of power transmission and differential gear operation into a single compact assembly. This consolidation eliminates the need for separate three-shaft offset arrangements and reduces overall structural complexity while maintaining the ability to direct drive power to wheel shafts.
3Ease of operation
If the ring gear is braked relative to a stationary housing for transmission stage change, then gear shifting can be achieved, but the device complexity and space requirements increase
Solution Approach 1:
The blocking device is designed to automatically engage and disengage based on the direction of rotation and operational conditions, without requiring complex external control mechanisms. The passive blocking capability allows the system to self-regulate the transmission stage changes, reducing the need for additional actuators and control systems.
4Area of stationary object
If a compact axial layout is achieved by integrating planetary gears radially inside the outer wheel, then installation space is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The planetary gears are nested radially inside the outer wheel, with precise radial positioning that allows the planet gears to mesh correctly with the sun gear while maintaining a compact axial profile. This nested arrangement requires high manufacturing precision to ensure proper gear engagement and smooth operation within the constrained radial space.
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
Shiftable two-speed transmission (2) for transmitting propulsion power within a motor vehicle drivetrain, comprising a rotationally driven input member via which, when propulsion power is being transmitted, the propulsion power is introduced into the transmission (2), and an output member via which the propulsion power can be transmitted out of the transmission (2), wherein subject to the shift position of a shiftable clutch (10), a direct drive (i=1) or a transmission stage having a transmission ratio (i#1) which differs from the direct drive can be achieved between the input member and the output member, and three assembly units, i.e. an external gear unit (4), a planetary gear unit (6) and a sun gear unit (8), are provided, characterized in that, when propulsion power is being transmitted, the propulsion power is introduced into the transmission (2) via the external gear unit (4).