Stepped Cone Synchronizer for High Breakthrough Load
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Solution Overview
Problem
Existing strut-type synchronizers in manual transmissions face limitations in achieving high breakthrough loads and efficient synchronization times due to constraints on detent spring rates and ramp angles, leading to increased parts count and torque-generation losses.
Innovation Solution
A synchronizer design featuring a stepped cone configuration with increased ramp angles and a detent system that achieves a breakthrough load greater than 100 N, along with a friction ring setup that eliminates direct contact between the sleeve and friction ring, allowing for rapid axial movement and reduced synchronization time without increasing parts count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the detent spring rate and ramp angle are increased to achieve higher breakthrough load, then the synchronization performance improves, but the detent complexity and manufacturing difficulty increase
Solution Approach 1:
The detent mechanism is segmented into distinct functional elements: the detent ball, the detent groove with ramps, and the detent spring. This segmentation allows each element to be optimized independently for its specific function while maintaining overall system performance.
Solution Approach 2:
The invention optimizes the ramp angle parameter of the detent groove to achieve the desired breakthrough load. By carefully selecting and adjusting the ramp angle along with the spring rate, the system achieves high breakthrough load without requiring overly complex detent structures.
2Power
If a traditional blocking ring design is used to generate cone torque, then the synchronization function is achieved, but the parts count increases and torque-generation losses occur
Solution Approach 1:
The invention merges the blocking ring function with the clutch ring by integrating the conical friction surface directly onto the clutch ring. This eliminates the need for a separate blocking ring component while maintaining the torque-generation function through the friction engagement between the clutch ring and friction ring.
Solution Approach 2:
The clutch ring is given multiple functions: it serves as both the synchronizing element that engages with the friction ring to generate cone torque, and as the coupling element that transmits power when engaged with the hub splines. This multi-functionality eliminates the need for a dedicated blocking ring.
3Loss of time
If the sleeve directly contacts the friction ring, then the structure is simplified, but the synchronization time increases due to friction resistance
Solution Approach 1:
The invention extracts the friction contact function from the sleeve by introducing a dedicated friction ring that interfaces with the clutch ring's conical surface. This separation allows the sleeve to move freely along the hub splines without frictional resistance, significantly reducing synchronization time.
Solution Approach 2:
The friction ring acts as an intermediary element between the sleeve assembly and the clutch ring. It provides the necessary frictional engagement for torque generation while allowing the sleeve to move independently without direct contact, thereby reducing synchronization time.
4Force
If the ramp angle is increased to maximize breakthrough load, then the detent performance improves, but the manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes the ramp angle parameter within a specific range that balances breakthrough load performance with manufacturing feasibility. By selecting an optimal ramp angle that is neither too shallow nor too steep, the system achieves high breakthrough load while maintaining reasonable manufacturing precision requirements.
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
The solution provides a significant increase in generated cone torque and reduced synchronization time, while maintaining a low parts count and minimizing tolerance stack-up, achieving synchronization times between 180-300 msec with a reduced overall axial dimension.
Implementation Method 1
The resulting frictional engagement between the blocking ring and the clutch ring generates a cone torque that rotationally accelerates or decelerates the clutch ring and its coupled gear relative to the blocking ring
Implementation Method 2
a detent spring disposed in each pocket of the hub such that a radially-inner end of the spring is supported by a radial surface of the hub, and a radially outer end of the spring extends through the radial passage defined in the strut to bias the detent ball into engagement with the sleeve's detent groove
Data Source
AI summary
A strut-type synchronizer for coupling a gear to a rotating shaft includes a hub rotating with the shaft, a clutch ring rotatable with the gear, and a friction ring disposed between the hub and the clutch ring. The hub supports several struts for relative axial movement, as urged by an encircling splined sleeve through a detent, into engagement with the friction ring. The friction ring, which does not itself directly engage the sleeve, has a friction surface that is thus urged by the struts into engagement with a complementary friction surface of the clutch ring, whereupon relative rotation between the friction ring and the clutch ring ceases, the detent is overcome, and the sleeve's spline teeth engage complementary spline teeth on the clutch ring to fully engage the synchronizer. The friction surfaces include two axially-spaced frustoconical portions, by which an increased cone torque is achieved during synchronization.