Automatic Transmission Input Speed Detection via Planetary Gear Sensors
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Solution Overview
Problem
Existing automatic transmissions face challenges in detecting input speed due to the central location of the input shaft, making it difficult to sense the rotation speed accurately, especially when trying to increase the number of speeds beyond five forward and one reverse.
Innovation Solution
The automatic transmission employs a planetary gear train with first, second, third, and fourth planetary gears, along with connection members and rotation sensors to calculate the input speed, allowing for the detection of input speed through sensing the rotation speeds of specific members, enabling the achievement of seven forward speeds and one reverse speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the input shaft is located at the center and enclosed by rotating members, then the transmission structure is compact, but the direct detection of input rotation speed becomes difficult
Solution Approach 1:
The patent uses intermediate rotating members (first and second connection members) that transmit rotation from the enclosed input shaft to the outside, where sensors can detect their rotation. These intermediaries allow indirect measurement of input shaft speed without compromising the compact enclosed structure.
Solution Approach 2:
The patent replaces direct mechanical access to the input shaft with a sensor-based detection system that measures rotation of accessible connection members. This substitution allows speed detection through magnetic or optical sensors rather than direct mechanical coupling to the enclosed shaft.
2Adaptability or versatility
If the number of speeds is increased beyond five forward and one reverse, then the transmission versatility improves, but the device complexity increases
Solution Approach 1:
The patent divides the planetary gear system into multiple independent planetary gear sets (first, second, third, and fourth planetary gears), each capable of providing different gear ratios. By segmenting the transmission into modular planetary sets that can be selectively engaged, the system achieves multiple speeds without requiring a single complex gear train.
Solution Approach 2:
The patent employs dynamic engagement and disengagement of planetary gear sets through clutches and brakes, allowing the transmission to shift between different speed ratios. The engaging device group dynamically configures which planetary gears are active, enabling versatile speed selection without permanent mechanical complexity.
Data Source
AI summary
An automatic transmission includes a planetary gear train of first, second, third and fourth planetary gears; an input rotation member connected with a ring gear of the second planetary gear; and a first connection member connecting a carrier of the second planetary gear and a ring gear of the fourth planetary gear. A first rotation sensor senses the rotation speed of the first connection member. A second rotation sensor senses the rotation speed of one rotating element of the first and second planetary gears. A processing section calculates an input speed of the automatic transmission from the rotation speeds sensed by the first and second rotation sensors.