Worm Reducer Assembly With Offset Insertion and Pre-Mounted Bearings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for assembling worm reducers in electric power steering devices are costly due to the separate mounting of the worm and rolling bearings, which increases manufacturing costs and can lead to damage during assembly.
Innovation Solution
A method of assembling a worm reducer where the worm and pair of rolling bearings are integrally mounted within the worm accommodation part of the housing, with the worm offset radially to avoid interference and allow meshing without backlash, using bearings with specific size relationships to minimize axial displacement and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the worm and rolling bearings are mounted separately in the worm accommodation part, then the assembly flexibility is improved, but the manufacturing cost increases and the risk of damage during assembly increases
Solution Approach 1:
The patent combines the worm and rolling bearings into a single integrated assembly unit. The worm shaft is designed with bearing mounting features integrated directly onto it, allowing the bearings to be pre-mounted on the worm shaft before insertion into the housing. This integration reduces the number of separate assembly steps and lowers manufacturing costs while maintaining assembly flexibility.
2Manufacturing precision
If the worm is inserted into the worm accommodation part with the worm teeth meshing with the worm wheel from the beginning, then the meshing precision is improved, but the risk of interference and damage during assembly increases
Solution Approach 1:
The patent employs preliminary positioning features on the worm shaft, such as alignment pins or guide surfaces, that ensure correct radial and axial positioning of the worm relative to the worm wheel before the worm teeth engage. This preliminary action prevents interference during insertion and ensures precise meshing is achieved without forcing or misalignment that could cause damage.
3Stability of the object's composition
If the outer diameter of the bearing is made larger to improve support stability, then the radial support stability is improved, but the bearing cannot pass the outer diameter-side of the worm wheel during insertion
Solution Approach 1:
The patent resolves the size conflict by changing the insertion dimension. Instead of inserting the bearing radially through the worm wheel's outer diameter, the bearing is inserted axially along the worm shaft. The worm shaft itself serves as the insertion path, allowing bearings of sufficient size for stable support to be mounted without encountering the radial dimension constraint imposed by the worm wheel's outer diameter.
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 approach reduces assembly and manufacturing costs while minimizing the risk of damage during assembly, allowing for efficient and cost-effective integration of the worm reducer components.
Implementation Method 1
a pair of rolling bearings (16a, 16b) such as deep groove ball bearings
Implementation Method 2
a worm 14 having worm teeth 13 formed on an axially intermediate portion of a worm shaft 12 and a worm wheel 15 configured to mesh with the worm teeth 13
Implementation Method 3
the worm teeth 13 and the tooth part 20 of the worm wheel 15 are meshed with each other
Implementation Method 4
an outer ring of the tip-side rolling bearing 16a (right, in FIG. 15) is internally fitted (internally fitted by interference fit) to a bearing holding part 22a
Data Source
Figure 1
Figure 2
Figure 3
AI summary
There is provided a method of assembling a worm reducer, which includes causing a worm wheel to be rotatably supported in a wheel accommodation part, externally fitting a pair of bearings at tip-side and base-side positions of a worm, inserting the worm into a worm accommodation part from an opening side thereof at a state where the worm is offset outward in a radial direction of the worm wheel with respect to a center axis of the worm accommodation part, causing the bearing which is externally fitted to a leading side in an insertion direction of the worm to pass an outer diameter-side of a part of an outer peripheral edge of the worm wheel, which protrudes most into the worm accommodation part, causing the worm teeth to mesh with the worm wheel, and further inserting the worm to a predetermined position in the worm accommodation part.