Rotation Detection for Internal Combustion Engine Transmission Gears
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Solution Overview
Problem
Conventional rotation detecting devices in internal combustion engines require either an increased gear width or the use of expensive high-sensitivity sensors to accurately detect the rotational speed of axially movable gears, leading to potential size increases in the engine and limited flexibility in system design.
Innovation Solution
A rotation detecting device is positioned to oppose a specific gear on the output shaft, which is fixed in its axial position, allowing for reliable rotational speed detection without increasing the gear width or using expensive sensors, and is located on the rear surface of the crankcase to minimize size and optimize system flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the width of the gear in the axial direction is increased to reliably detect rotational speed, then detection reliability is improved, but the axial width of the internal combustion engine increases
Solution Approach 1:
The patent uses a master gear whose rotational speed is copied to the slave gear through meshing engagement. The rotation detecting device only needs to detect the rotational speed of the master gear, and this information is transferred to the axially movable slave gear through the gear meshing relationship, eliminating the need for the slave gear to have increased width for detection purposes
Solution Approach 2:
The master gear acts as an intermediary between the rotation detecting device and the axially movable slave gear. The detection device detects the master gear's rotation, and this rotational information is transmitted through the meshing gears to provide rotational speed information of the slave gear without requiring the detection device to directly track the moving slave gear
2Measurement precision
If an expensive sensor with high sensitivity is used to detect rotational speed of axially movable gear, then detection precision is improved, but manufacturing cost increases
Solution Approach 1:
Instead of attempting to directly detect the rotational speed of the axially movable slave gear, the patent inverts the approach by detecting the rotational speed of the stationary master gear through which the slave gear's rotation is transmitted. This allows the use of standard, cost-effective sensors rather than expensive high-sensitivity sensors
3Adaptability or versatility
If the specific gear is positioned near the shift ends of the transmission, then detection capability is improved, but the shaft length must be increased to accommodate bearing relocation
Solution Approach 1:
The master gear serves multiple functions: it is engaged with the slave gear to transmit rotational information, it is positioned to allow detection by the rotation detecting device, and it enables detection without requiring extended shaft length or bearing relocation. This multi-functional design achieves detection capability while maintaining compact transmission dimensions
Data Source
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AI summary
Disclosed herein is an internal combustion engine (E) having a crankcase (335) in which a crankshaft (336) and a transmission (M) are accommodated, the transmission (M) having a plurality of gears for shifting, an input shaft for inputting a rotational drive force from the crankshaft (336), and an output shaft to which the rotational drive force is transmitted from the input shaft through the gears, the rotational drive force being further transmitted from the output shaft to a drive wheel. The internal combustion engine (E) includes rotation detecting devices (401 and 402) for respectively detecting the rotational speeds of the gears (49c and 49d) included in the transmission (M), the rotation detecting devices (401 and 402) respectively having detecting portions (401a and 402a) opposed to the gears (49c and 49d) rotating with the rotation of the input shaft (28) and positioned in the axial direction of the transmission (M).