Concentric V-Groove Coupling for Automotive Transmission Efficiency
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Solution Overview
Problem
Conventional automotive transmissions with planetary gear-sets suffer from high no-load losses, resulting in low efficiency, especially during highway driving, where 70% of vehicle use requires only 20 to 25 hp, leading to a transmission efficiency of about 50% due to parasitic losses.
Innovation Solution
The transmission drive-line stage incorporates a torque coupling system with a centre member having opposing surfaces at an acute angle, radially offset roots, and a centering mechanism, along with oil passages for cascading oil flow, to reduce parasitic losses and improve efficiency by coordinating the engagement of clutch plates and end members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional planetary gear-sets and multi-disc/plate couplings are used, then the transmission structure is simple and reliable, but parasitic no-load losses are high (15,000-20,000 watts) resulting in low efficiency (about 50%)
Solution Approach 1:
The coupling is divided into a centre member with V-grooved surfaces and end members with corresponding V-grooves, creating discrete engagement zones. This segmentation allows for reduced contact area and lower parasitic losses while maintaining torque transmission capability through the V-groove engagement geometry
Solution Approach 2:
The patent replaces the conventional multi-disc/plate friction-based coupling mechanism with a V-groove mechanical engagement system. This substitution reduces parasitic losses by eliminating sliding friction between multiple discs and instead using positive mechanical engagement through the V-groove geometry, achieving 66-75% reduction in no-load losses
2Loss of energy
If the centre member has opposing surfaces at an acute angle with radially offset roots, then parasitic losses are reduced by 66% to 75%, but the manufacturing precision requirements increase
Solution Approach 1:
The centre member features asymmetric V-groove configurations with radially offset roots on opposing surfaces. This asymmetry creates non-uniform engagement patterns that reduce parasitic losses by 66-75% compared to symmetric designs, while the acute angle between opposing surfaces optimizes the mechanical engagement geometry for reduced friction
Solution Approach 2:
The V-grooves are positioned at specific radial offsets and acute angles to create localized optimal engagement zones. This local quality optimization reduces parasitic losses in critical areas while maintaining overall coupling functionality, with the acute-angled opposing surfaces creating favorable stress distribution patterns
3Reliability
If a centering mechanism with ball bearing or spring is added, then the coupling engagement is improved and torque discontinuity is reduced, but the device complexity increases
Solution Approach 1:
A centering mechanism comprising a ball bearing or spring coupled to a rotational shaft is introduced as an intermediary element. This mediator maintains proper alignment between the centre member and end members during engagement, reducing torque discontinuity and improving coupling reliability without requiring complex external coordinating mechanisms
Solution Approach 2:
The centering mechanism uses the rotational shaft itself as part of the centering system, with the ball bearing or spring coupled directly to the shaft. This self-service approach allows the rotating component to maintain its own alignment, reducing the need for additional external centering devices and minimizing overall system complexity
4Loss of energy
If oil passages are added to facilitate cascading oil flow, then lubrication is improved and efficiency is increased, but the manufacturing complexity increases
Solution Approach 1:
Oil passages are configured to facilitate continuous cascading oil flow from the centre member to the V-grooves of the end members. This continuous lubrication action reduces friction losses throughout the coupling operation, with oil flowing through passages that extend radially through multiple roots to maintain consistent lubrication at all engagement 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 decreases parasitic/no-load losses by 66% to 75% and allows for smooth gear ratio transitions without external coordinating mechanisms, achieving higher efficiency and reducing drive-line torque discontinuity.
Implementation Method 1
a spring coupled to a rotational shaft
Implementation Method 2
The centering mechanism may comprise a ball bearing or a spring coupled to a rotational shaft
Implementation Method 3
conventional automotive transmissions having three or more planetary gear sets
Implementation Method 4
at least one oil passage that is configured to facilitate a cascading oil flow to the V-grooves of the end members
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A coupling comprises a pair of clutch end members, a clutch centre member disposed between the clutch end members, and an actuator coupled to one of the end members. Each end member includes concentric V-grooves disposed on a respective face thereof. The centre member is axially movable between the end members, and includes a pair of opposing surfaces. One of the opposing surfaces includes concentric V- grooves configured to mesh with the V-grooves of one of the end members. Another of the opposing surfaces includes concentric V-grooves configured to mesh with the V-grooves of another of the end members. The actuator is configured to couple the end members and the centre member together by urging the V-grooves of the end members into engagement with the V-grooves of the centre member.