Automatic Transmission Spline Engagement for Torque Fluctuation
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Solution Overview
Problem
Existing vehicular automatic transmissions face challenges in suppressing torque fluctuation without increasing the number of components, which can lead to reduced transmission efficiency and higher manufacturing costs due to the need for additional inertia members.
Innovation Solution
The automatic transmission employs a spline engagement portion with a tolerance ring to co-rotate a non-torque transmitting rotating element, consuming inertia energy through collisions with spline teeth, thereby reducing torque fluctuation without the need for additional components like inertia members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inertia member is added to suppress torque fluctuation, then torque fluctuation suppression is improved, but the mass of the automatic transmission increases
Solution Approach 1:
The rotating element that is already present in the automatic transmission serves dual purposes: it functions as a structural component of the transmission and simultaneously acts as an inertia member to suppress torque fluctuation. The rotating element has an inertia value greater than or equal to a predetermined value, allowing it to dampen torque fluctuations from the engine without requiring any additional dedicated inertia members.
Solution Approach 2:
The rotating element is designed to perform multiple functions: it is integral to the transmission's power transmission mechanism while also serving as the inertia member for torque fluctuation suppression. This multi-functionality eliminates the need for separate components, thereby avoiding mass increase while maintaining effective torque fluctuation suppression.
2Reliability
If a separate inertia member is provided, then torque fluctuation suppression is improved, but manufacturing cost increases
Solution Approach 1:
The rotating element that is already part of the transmission assembly serves the additional function of torque fluctuation suppression. Since no separate inertia member needs to be manufactured, assembled, or maintained, the manufacturing cost is reduced while still achieving the desired torque fluctuation suppression effect.
Solution Approach 2:
By designing the rotating element to simultaneously serve as both a transmission component and an inertia member, the invention eliminates the need for additional manufacturing processes, parts procurement, and assembly operations that would be required for a separate inertia member, thereby reducing overall manufacturing cost.
3Reliability
If the inertia of the automatic transmission is increased, then torque fluctuation suppression is improved, but transmission efficiency decreases
Solution Approach 1:
The rotating element utilizes its existing rotational mass to suppress torque fluctuation without adding dedicated inertia components. This approach increases the effective inertia for damping purposes while minimizing additional mass that would otherwise increase rotational inertia and reduce transmission efficiency.
Solution Approach 2:
The invention carefully controls the inertia value of the rotating element to be greater than or equal to a predetermined value, optimizing the balance between torque fluctuation suppression and transmission efficiency. By adjusting and optimizing the inertia parameter rather than simply increasing it, the system achieves effective damping while maintaining acceptable transmission efficiency.
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 approach effectively suppresses torque fluctuation across various engine speeds, improving transmission efficiency and reducing manufacturing costs by eliminating the need for extra components, while maintaining noise-vibration performance.
Implementation Method 1
the energy of inertia due to torque fluctuation of the engine is consumed, and torque fluctuation delivered from the output shaft of the automatic transmission can be suppressed
Implementation Method 2
collisions are repeated in the spline engagement portion. Owing to the collisions, the energy of inertia due to torque fluctuation of the engine is consumed
Implementation Method 3
backlash in the spline engagement portion is substantially eliminated. Accordingly, backlash formed on the power transmission path consists solely of backlash formed at meshing parts of gears
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A vehicular automatic transmission includes a plurality of engagement devices (B1, B2, C1, C2, C3, C4) and a plurality of planetary gear sets (36, 38, 40). Each of the planetary gear sets (36, 38, 40) includes rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3). At least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) of one of the plurality of planetary gear sets (36, 38, 40) is coupled to one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) of another planetary gear set or one of the engagement devices (B1, B2, C1, C2, C3, C4), via a spline engagement portion (82). The rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) other than the at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion (82) is coupled to another rotating element or a non-rotary member (18) directly or via one of the engagement devices (B1, B2, C1, C2, C3, C4). The at least one of the rotating elements (S1, S2, S3, CA1, CA2, CA3, R1, R2, R3) coupled via the spline engagement portion (82) is configured to be co-rotated with no torque transmitted via the spline engagement portion (82), when the automatic transmission is placed in a predetermined gear position as one of the plurality of gear positions.