Automatic Transmission Reverse Shift Noise Control
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Solution Overview
Problem
Existing automatic transmissions with 8-forward-speed and 1-reverse-speed configurations using four planetary gear sets and six engagement mechanisms face challenges in efficiently managing gear ratios and preventing reverse rotation during shifts, leading to inefficiencies and potential noise issues.
Innovation Solution
An automatic transmission system incorporating an input member, planetary gear sets, engagement mechanisms, a shift position detecting unit, an input rotational speed detecting unit, a control unit, and a switching mechanism that allows for reverse rotation prevention and fixed modes, enabling smooth transitions and efficient speed changes by controlling the engagement mechanisms based on detected shift positions and rotational speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switching mechanism is added to prevent reverse rotation, then reverse rotation prevention is improved, but device complexity increases
Solution Approach 1:
The switching mechanism is designed to perform multiple functions: it prevents reverse rotation during forward drive range shifts while also enabling fixed mode operation during reverse drive range shifts. This multi-functionality reduces the need for separate mechanisms for each function, thereby improving reliability without proportionally increasing device complexity.
Solution Approach 2:
The switching mechanism utilizes the existing planetary gear set structure and engagement mechanisms to achieve reverse rotation prevention. By integrating the reverse rotation prevention function into the existing gear train rather than adding a completely independent system, the patent reduces overall system complexity while maintaining reliability.
2Object-generated harmful factors
If engagement mechanisms are controlled to reduce switching noise, then noise reduction is improved, but control complexity increases
Solution Approach 1:
The control mechanism prepares the engagement mechanisms in advance before actual shifting occurs. By pre-positioning clutches and brakes and gradually engaging them while controlling rotational speed, the system reduces冲击 and noise during shifting without requiring complex real-time control algorithms.
Solution Approach 2:
The control mechanism dynamically adjusts the engagement state of clutches and brakes during shifting operations. By continuously monitoring rotational speed and gradually transitioning engagement mechanisms from disengaged to engaged states, the system minimizes noise while maintaining simple control logic based on speed thresholds.
3Adaptability or versatility
If multiple engagement mechanisms are used to manage gear ratios, then gear ratio management is improved, but device complexity increases
Solution Approach 1:
The transmission system divides gear ratio management into multiple independent engagement mechanisms (clutches and brakes), each responsible for specific gear ranges. This segmentation allows versatile gear ratio control while keeping each individual mechanism relatively simple, reducing overall control complexity.
Solution Approach 2:
The patent combines multiple engagement mechanisms (clutches and brakes) with the planetary gear set into an integrated system. By merging these components rather than using separate transmission systems, the patent achieves versatile gear ratio management while reducing overall device complexity through component integration.
Data Source
AI summary
An automatic transmission includes an input member, a planetary gear set, a plurality of engagement mechanisms, an output member, a shift position detecting unit, an input rotational speed detecting unit, a control unit, and a switching mechanism. When a shift position is changed from a forward drive range to a reverse drive range, the control unit performs a reverse preparation mode in which a rotational speed of an element to be fixed by the switching mechanism is lower than or equal to a predetermined speed by setting an engagement mechanism in one of a connection mode and a fixed mode. Upon performing the reverse preparation mode, the control unit engages the engagement mechanism that connects the element fixed by the switching mechanism to the input member and, thereafter, engages the engagement mechanism that makes the rotational speed of the input member lower than or equal to the predetermined speed.