Compound Gear Reduction Transmission for High Torque
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Solution Overview
Problem
Existing vehicle drivelines face challenges in achieving a high numeric rotational speed reduction ratio, such as 7.46:1, without increasing packaging volume, parts, and cost, particularly in two shaft transmissions where implementing a 'granny gear' is difficult.
Innovation Solution
A transmission system with a compound ratio gear set comprising a master active gear set, a slave active gear set, and a passive gear set, where the passive gear set selectively engages the master and slave active gear sets to provide a high numeric compound ratio rotational speed reduction, allowing for a 7.46:1 reduction ratio without additional transmission shafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single gear set is used between two shafts in a transmission, then the structure is simple, but it is difficult to achieve a high numeric reduction ratio (e.g., 7.46:1)
Solution Approach 1:
The transmission system divides the single gear set into multiple gear sets (first gear set, second gear set, third gear set) arranged in a compound configuration. Each gear set provides a portion of the total reduction ratio, and their combined effect achieves the high numeric reduction ratio of 7.46:1 while maintaining a relatively simple two-shaft structure.
2Productivity
If two or more additional transmission shafts are added to achieve high reduction ratio and correct rotation direction, then the desired low gear ratio is achieved, but packaging volume, parts, and cost increase
Solution Approach 1:
The patent merges the functions of multiple shafts into a two-shaft configuration by using compound gear sets that can simultaneously achieve high reduction ratio and correct output rotation direction. The first, second, and third gear sets are arranged to transfer power from the input shaft to the output shaft while maintaining compact packaging volume.
3Productivity
If two or more additional transmission shafts are added to achieve high reduction ratio and correct rotation direction, then the desired low gear ratio is achieved, but the number of bearings and machined bores increases
Solution Approach 1:
The patent consolidates the transmission into a two-shaft design where compound gear sets perform multiple functions. The first gear set includes a first driven gear and first drive gear, the second gear set includes a second driven gear and second drive gear, and the third gear set includes a third driven gear and third drive gear, all arranged to achieve the 7.46:1 reduction ratio without requiring additional shafts, bearings, or machined bores.
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
The solution enables vehicles to navigate challenging terrain by providing high torque and low rotational speed, reducing the need for complex gearing systems and additional components, thus optimizing space and cost within the transmission.
Implementation Method 1
The gear sets comprise a master active gear set having a master gear ratio, a slave active gear set having a slave gear ratio, and a passive gear set having a passive gear ratio. The passive gear set is operable to selectively engage the master and slave active gear sets to provide the high numeric compound ratio rotational speed reduction that is the product of the master active gear ratio, the slave active gear ratio and the passive gear ratio.
Data Source
AI summary
A transmission comprising an input shaft connectable to a power generation device such that the input shaft is rotatable at a power input rotational speed, an output shaft connectable to a driveline of the vehicle, and a plurality of gear sets selectable to operably connect the input shaft to the output shaft providing a rotational speed reduction ratio therebetween. The gear sets comprise a master active gear set having a master gear ratio, a slave active gear set having a slave gear ratio, and a passive gear set having a passive gear ratio. The passive gear set is operable to selectively engage the master and slave active gear sets to provide the high numeric compound ratio rotational speed reduction that is the product of the master active gear ratio, the slave active gear ratio and the passive gear ratio.