Transmission Synchronizer Hub Phasing With Round Cavities
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Solution Overview
Problem
Existing synchronizers for mechanical transmissions face manufacturing complexity and reduced mechanical strength due to the rectangular cross-section cavities in the phasing system, which require dedicated machining and result in large blocking elements that compromise the hub's size and strength.
Innovation Solution
The phasing system is redesigned with arc- or round-shaped cavities on the hub's internal surface, allowing simpler manufacturing and increased mechanical strength, and the blocking elements are configured with tangentially protruding engaging members, reducing their radial size and eliminating the need for deep cavities in the hub.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rectangular cross-section cavities are used in the phasing system, then the synchronizer can be manufactured with standard machining processes, but the manufacturing complexity increases and the mechanical strength of the hub is reduced
Solution Approach 1:
The patent applies curvature by changing the cavity cross-section from rectangular to arc-shaped (circular or semi-circular). This curvature eliminates sharp corners that act as stress concentration points, thereby improving the mechanical strength of the hub while maintaining manufacturability through standard drilling and machining processes.
2Reliability
If blocking elements are made with radial protrusion configuration, then the engaging members can effectively engage with the actuating sleeve, but the radial size of blocking elements increases requiring deep cavities in the hub
Solution Approach 1:
The patent changes the dimension of protrusion from radial to tangential direction. By making the engaging members protrude tangentially rather than radially, the blocking elements achieve effective engagement with the actuating sleeve while significantly reducing their radial size, thereby eliminating the need for deep cavities in the hub.
3Device complexity
If deep cavities are provided in the hub for blocking elements, then the blocking elements can be accommodated, but the mechanical strength of the hub is reduced and the maximum shaft diameter is limited
Solution Approach 1:
The patent uses arc-shaped cavities with curved cross-sections that better distribute stress and eliminate sharp corners, improving the mechanical strength of the hub while providing adequate accommodation for the blocking elements.
Solution Approach 2:
By changing the blocking elements to tangential protrusion, the patent reduces the radial space requirement, allowing shallower cavities that do not compromise the hub's structural integrity and enable larger shaft diameters.
4Ease of manufacture
If rectangular cavities are used in the phasing system, then the teeth can be easily machined, but the hub requires dedicated complex machining and has reduced mechanical strength
Solution Approach 1:
The patent replaces rectangular cavities with arc-shaped cavities that can be manufactured using standard drilling and rounding operations, eliminating the need for complex dedicated machining processes while improving the hub's mechanical strength by removing stress concentration points.
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 configuration simplifies manufacturing, enhances mechanical strength, and allows for a larger hub diameter, enabling the synchronizer to be used on larger shafts while reducing weight and cost by using plastic materials for the blocking elements.
Implementation Method 1
a coil spring accommodated in the hollow body and extending with its axis in a radial direction
Implementation Method 2
a friction surface (in particular a conical surface) arranged to be brought into engagement with a corresponding friction surface associated to the respective gear wheel to allow the generation of a friction torque
Data Source
Figure 1
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AI summary
The synchronizer (10) comprises: a hub (18) provided with external teeth (22); an actuating sleeve (24) provided with internal teeth (26) meshing with the external teeth (22) of the hub (18); at least one synchronizing ring (28) that is provided with external teeth (30) arranged to mesh with the internal teeth (26) of the actuating sleeve (24) and has, on its radially internal side, a friction surface (32) arranged to cooperate with a friction surface (40) associated to a respective gear wheel (14, 16) to allow generation of a friction torque between the synchronizing ring (28) and the associated gear wheel (14, 16); a pre-synchronization system comprising a plurality of blocking elements (42) operatively placed between the hub (18) and the actuating sleeve (24); and a phasing system (60, 62; 70, 72, 74) arranged to ensure a given angular positioning of the synchronizing ring (28) with respect to the hub (18) about the longitudinal axis (x). The phasing system (60, 62; 70, 72, 74) comprises a plurality of first cavities (62; 74) provided on an internal cylindrical surface (66) of a ring gear (68) of the hub (18) forming the external teeth (22) of the hub (18), each of said first cavities (62; 74) having an arc- or round-shaped cross-section, in particular a semi-circular cross-section.