Speed Reducer Gear Tooth Geometry for Lower Engagement Noise
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Solution Overview
Problem
Industrial robots operating near humans generate noise due to the high-speed rotation of the input gear relative to the spur gears in existing speed reducers, leading to loud noise at their engagement.
Innovation Solution
A speed reducer design featuring an outer tube with internal teeth, a carrier attached to an output shaft, crankshafts with eccentric portions, oscillating gears, and transmission gears with specific tooth configurations (coefficient of addendum 1.2-1.3, dedendum 1.25-1.55, pressure angle 14.5-20°, tooth thickness 3-30 mm, and module 0.8-3.0) to reduce noise at the engagement between the input gear and transmission gears.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the input gear rotates at high speed to achieve efficient power transmission, then productivity is improved, but noise generated at the engagement between the input gear and spur gears increases
Solution Approach 1:
The patent changes the geometric parameters of the gear teeth by specifying a coefficient of length of addendum between 1.2-1.3 and a coefficient of length of dedendum between 1.25-1.55. These parameter modifications alter the engagement characteristics between gears, reducing impact and noise while maintaining efficient power transmission at high speeds
2Ease of manufacture
If standard gear dimensions are used to simplify manufacturing, then ease of manufacture is improved, but noise reduction capability deteriorates
Solution Approach 1:
The patent specifies precise parameter ranges (coefficient of length of addendum: 1.2-1.3, coefficient of length of dedendum: 1.25-1.55, pressure angle: 14.5-20°) that balance manufacturing feasibility with noise reduction. These modified parameters enable noise reduction while remaining within practical manufacturing capabilities
3Object-generated harmful factors
If the coefficient of length of addendum and dedendum are increased to reduce noise, then noise level is lowered, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific ranges for addendum coefficient (1.2-1.3) and dedendum coefficient (1.25-1.55) that optimize noise reduction while considering manufacturing precision capabilities. These parameter specifications provide a balanced design space that achieves noise reduction without requiring excessive manufacturing precision
Data Source
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AI summary
A speed reducer (1) relating to one aspect of the present invention includes a carrier (12) rotatably provided inside an outer tube (11) and fixedly attached to an output shaft, an input shaft (3) provided on a driving source, a plurality of crankshafts (13) rotatably supported by the carrier (12) and connected to the input shaft (3), where the crankshafts (13) each have an eccentric portion eccentric to an axis of rotation of the output shaft, oscillating gears (14, 16) configured to oscillatorily rotate together with the eccentric portions of the crankshafts (13), a plurality of spur gears (20) configured to rotate when acted upon by the oscillatory rotation of the oscillating gears (14, 16), where the spur gears (20) are respectively coaxial with the crankshafts (13), and an input gear (30) provided on the input shaft (3), where the input gear (30) engages with the spur gears (20) to synchronously rotate the spur gears (20). The input gear (30) and the spur gears (20) engage with each other with 6 to 8 teeth or the input gear (30) and the spur gears (20) are configured such that a coefficient of length of addendum is no less than 1.2 and no more than 1 .3, and a coefficient of length of dedendum is greater than 1.25 and no more than 1.55.