Planetary Gear Train Dog Clutch Layout for Continuous Shifting
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Solution Overview
Problem
Existing shiftable planetary transmissions face challenges in achieving compact design and efficient gear shifting without interrupting tractive force, particularly in lower gear step ranges.
Innovation Solution
A compact shiftable planetary transmission design featuring a planet carrier with axially displaceable connecting elements that actuate a ring-shaped dog element between multiple shift positions, allowing for form-locking connections with sun and ring gears, enabling efficient gear ratio changes without interrupting power flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple friction-locking shift elements and form-locking shift elements are arranged between shafts and housing to enable gear step changeovers without interruption of tractive force, then shifting between gear ratios can be achieved without interrupting power flow, but the device complexity and spatial requirements increase
Solution Approach 1:
The patent combines multiple shift elements (friction-locking and form-locking) into a unified planetary gear set architecture where dog elements are integrated directly with the planet carrier and sun gear. This merging reduces the number of separate components needed while maintaining the ability to achieve continuous power flow during gear transitions.
Solution Approach 2:
The planet carrier serves multiple functions: it supports planet gears, houses dog elements for form-locking connections, and provides structural integration for the shifting mechanism. This multi-functionality reduces the need for separate dedicated components for each shifting function.
2Reliability
If shift elements are positioned in the housing and brought into operative connection without being acted upon by rotating components, then gear stage changes can be implemented safely, but the compactness and integration of the transmission are reduced
Solution Approach 1:
The dog elements are arranged axially on the planet carrier, utilizing the axial dimension for shift positioning rather than requiring radial or longitudinal separation. This axial arrangement allows compact integration within the planetary gear set volume while maintaining safe actuation through the connecting element mechanism.
Solution Approach 2:
The dog elements are nested within the planetary gear set structure, with the first dog element integrated into the planet carrier and the second dog element connected to the sun gear. This nesting allows the shifting mechanism to be contained within the existing gear train volume without requiring additional external space.
3Productivity
If a connecting element is axially displaceable through the planet carrier to actuate dog elements between shift positions, then compact rapid shifting is achieved, but the precision of form-locking connection engagement increases difficulty
Solution Approach 1:
The connecting element acts as an intermediary that translates axial displacement into precise form-locking engagement. It mediates between the actuator and the dog elements, ensuring that the rapid axial motion results in accurate tooth-to-tooth engagement of the form-locking connections.
Solution Approach 2:
The dog elements are pre-positioned on the planet carrier and sun gear with their toothing surfaces prepared for engagement. The connecting element's axial displacement brings these pre-positioned elements into engagement, allowing rapid shifting without requiring complex real-time alignment during the shifting action.
Data Source
AI summary
A shiftable planetary transmission (1) includes a planet carrier (2), a plurality of planet gears (3) rotatably arranged at the planet carrier (2), a sun gear (4), and a ring gear (5). The sun gear (4) and the ring gear (5) mesh with the planet gears (3). The planet carrier (2) includes at least one connecting element (6), which is axially displaceable therein. The at least one connecting element (6), on a first side of the planet carrier (2), is at least indirectly connected to an actuator (7) and, on a second side of the planet carrier (2), is at least indirectly connected to a first dog element (8). The first dog element (8) is displaceable, by an actuator actuation, between a first shift position and at least a second shift position due to an axial displacement of the at least one connecting element (6) in the planet carrier (2).