Eccentric Rocking Speed Reducer Part Reduction
Solution Overview
Problem
Existing eccentrically oscillating speed reducers have a large number of parts, which increases complexity and cost, and can lead to uneven wear and reduced service life due to the use of rolling bearings and complex tooth mesh configurations.
Innovation Solution
The design eliminates rolling bearings by using an inter-crankshaft gear with outer teeth that mesh with the crankshafts at a middle portion, reducing the number of parts and incorporating oil films for frictional sliding, which prevents uneven wear and extends the service life by ensuring uniform meshing and reduced fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rolling bearings are used to support the inter-crankshaft gear, then the gear is properly supported, but the number of parts increases
Solution Approach 1:
The support function for the inter-crankshaft gear is merged with the crankshaft structure itself. The crankshaft body directly supports the inter-crankshaft gear through integrated bearing surfaces and oil film formation, eliminating the need for separate rolling bearings. This combining of support functions reduces part count while maintaining reliability through the oil film bearing mechanism.
Solution Approach 2:
The rolling bearing components are extracted and removed from the system. Instead of using discrete bearing elements, the support function is achieved through the oil film mechanism integrated into the crankshaft- gear interface, simplifying the overall structure.
2Power
If the inter-crankshaft gear meshes with crankshafts at end portions, then power transmission is achieved, but uneven wear occurs due to crankshaft bending
Solution Approach 1:
The meshing position is asymmetrically placed at the middle portion of the crankshaft rather than at the ends. This asymmetric positioning relative to the crankshaft structure exploits the stiffness distribution to minimize bending effects and achieve more uniform load distribution across the tooth contact area.
Solution Approach 2:
The middle portion of the crankshaft is selected as the meshing location because it has different local mechanical properties (higher stiffness, lower bending) compared to the end portions. This local quality difference is utilized to prevent uneven wear and extend service life.
3Reliability
If inner teeth are used in the inter-crankshaft gear, then meshing with outer teeth of crankshafts is achieved, but fabrication cost increases
Solution Approach 1:
Instead of using the conventional inner teeth configuration in the inter-crankshaft gear, the design inverts the approach by using outer teeth. This inversion simplifies the manufacturing process and reduces fabrication costs while maintaining reliable meshing with the crankshaft gears.
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
This configuration reduces the number of parts, prevents uneven wear, and extends the service life of the speed reducer components while lowering fabrication costs by eliminating rolling bearings and optimizing the gear meshing mechanism.
Implementation Method 1
an oil film is provided between the inter-crankshaft gear and the outer teeth member, and the eccentrically oscillating speed reducer is configured such that the inter-crankshaft gear frictionally slides relative to the outer teeth member by way of the oil film
Implementation Method 2
an outer teeth member having outer teeth brought in mesh with the inner teeth of the first member and eccentrically moved by the crankshaft
Data Source
Figure 1
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AI summary
There is provided an eccentrically oscillating speed reducer capable of reducing a number of parts more than that of a background art. An eccentrically oscillating speed reducer 100 includes a case 110 having inner teeth 110a, a plurality of crankshafts having outer teeth, outer teeth gears 131 and 132 having outer teeth 131a and 132a brought in mesh with the inner teeth 110a of the case 110 and eccentrically moved by the crankshafts, a carrier 140 rotatably supporting the crankshafts and rotated to move relative to the case 110 by the crankshafts, and a cylindrical gear 180 brought in mesh with the outer teeth of the crankshafts for transmitting a power inputted to one crankshaft 121 of the plurality of crankshafts to remaining crankshafts, and the cylindrical gear 180 is rotatably supported by sliding friction.