Planetary Clutch Reducer Layout to Prevent Double-Tooth Meshing
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Solution Overview
Problem
Conventional clutch devices face issues with increased gear width due to the need for two ring gears in series, leading to reduced clearance and potential double-tooth meshing phenomena, which can cause operational failures.
Innovation Solution
The clutch device incorporates a speed reducer with a sun gear and planetary gear configuration where the gear width of the sun gear is set to be smaller than the planetary gear, maintaining a secure gap and preventing double-tooth meshing, and includes a state changing unit that adjusts the clutch state based on the axial position of a translation portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If two ring gears are arranged in series to achieve torque reduction, then the speed reduction function is improved, but the gear width increases and clearance is reduced leading to double-tooth meshing phenomena
Solution Approach 1:
The speed reduction function is segmented into two independent planetary gear sets (first and second planetary gear sets) with different reduction ratios, rather than using two ring gears in series. Each planetary gear set operates independently with its own sun gear, planetary gears, and ring gear, eliminating the double-tooth meshing issue while achieving cumulative torque reduction.
Solution Approach 2:
The patent transitions from a single-axis series arrangement of two ring gears to a parallel configuration where two planetary gear sets operate simultaneously on the same axis. The differential rotation paths of the two planetary gear sets are combined through a differential mechanism, adding a dimensional aspect to the torque transmission that prevents meshing interference.
2Strength
If gear width is increased to accommodate two ring gears in series, then torque transmission capacity is improved, but meshing clearance is reduced causing double-tooth meshing
Solution Approach 1:
The torque transmission function is divided between two separate planetary gear sets with different reduction ratios. The first planetary gear set handles initial torque reduction while the second planetary gear set provides additional reduction. This segmentation allows each gear set to maintain appropriate meshing clearance while collectively achieving high torque transmission capacity.
Solution Approach 2:
The patent changes the reduction ratio parameter between the two planetary gear sets, with the first set having a different ratio than the second set. This parameter differentiation allows optimal meshing clearance to be maintained in each stage while achieving cumulative torque multiplication, avoiding the double-tooth meshing that occurs with identical ratio series arrangements.
3Device complexity
If conventional clutch control is used without axial position sensing, then device complexity is reduced, but clutch engagement precision deteriorates
Solution Approach 1:
The patent replaces complex electronic sensing and control systems with a purely mechanical axial position sensing mechanism. The translation portion's axial position directly controls the clutch engagement state through mechanical coupling, eliminating the need for sensors, actuators, and electronic control while maintaining precise engagement control based on actual axial position.
Data Source
AI summary
A prime mover includes a stator fixed to a housing, and a rotor rotatable relative to the stator. The prime mover is capable of outputting torque from the rotor by being supplied with electric power. A speed reducer is capable of reducing the torque of the prime mover and outputting the reduced torque. The speed reducer includes a sun gear rotatable integrally with the rotor, and planetary gears capable of revolving in a circumferential direction of the sun gear while rotating in a state of meshing with the sun gear. A gear width of the sun gear is set such that a length in the axial direction by which the sun gear and the planetary gear are overlapped is smaller than a gear width of the planetary gear.