Ball Cage Spacing in Telescopic Drawer Runners to Reduce Jerking
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Solution Overview
Problem
Telescopic rails experience running discontinuities and jerking under mechanical loads, particularly after prolonged exposure, due to uneven distances between rolling elements in ball cages, which worsen with increased numbers of rolling elements.
Innovation Solution
Designing a ball cage with at least four rolling elements having different distances between their axes of rotation, where these distances are not integral multiples or sums of each other, and using a U-shaped cross-section with symmetrical holding sections to reduce manufacturing deviations and improve stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If rolling elements are arranged with equal distances in ball cages, then manufacturing is simplified, but running discontinuities and jerking occur under mechanical loads
Solution Approach 1:
The patent applies asymmetry by deliberately arranging rolling elements with different distances between them in the ball cage. Specifically, at least four rolling elements are positioned such that the distances between their axes of rotation are not equal and not integral multiples or sums of each other. This asymmetric arrangement prevents synchronous vibrations and running discontinuities that occur with equal spacing, thereby improving running smoothness under mechanical loads while maintaining manufacturability through standardized ball cage components.
Solution Approach 2:
The patent implements local quality by varying the spacing of rolling elements at specific positions within the ball cage rather than applying uniform spacing throughout. The different distances between rolling elements are strategically configured in the longitudinal direction to address local vibration issues, while other aspects of the ball cage structure remain standardized for ease of manufacture.
2Force
If the number of rolling elements is increased to improve load distribution, then load capacity increases, but jerking and running discontinuities worsen
Solution Approach 1:
The patent resolves this contradiction by combining an increased number of rolling elements with asymmetric spacing. By arranging at least four rolling elements with different distances between their axes of rotation that are not integral multiples or sums of each other, the design distributes load across more elements while preventing the synchronous vibrations that cause jerking. This breaks the direct correlation between increased rolling element count and worsened running smoothness.
3Manufacturing precision
If rolling elements are arranged with distances that are integral multiples or sums of each other, then manufacturing precision is easier to maintain, but running discontinuities occur under prolonged mechanical loads
Solution Approach 1:
The patent addresses this contradiction by specifying that distances between rolling elements should not be equal and should not be integral multiples or sums of each other. This asymmetric arrangement ensures that even with normal manufacturing tolerances, the rolling elements do not synchronize their motion cycles, preventing running discontinuities and jerking under prolonged mechanical loads while remaining achievable with standard manufacturing precision.
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
Significantly reduces jerking and enhances steadiness in telescopic extensions even under long-term mechanical loads by ensuring varied distances between rolling elements, leading to improved running properties and reduced sliding resistance.
Implementation Method 1
The ball cage keeps rolling elements at a certain distance from one another in the running direction, which corresponds to the longitudinal direction of rail elements, and also generally prevents the rolling elements from falling out of the telescopic extension
Implementation Method 2
rolling elements are arranged in the first holding section... which are separated from one another by webs and in which rolling elements are arranged
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3~4
AI summary
The present invention relates to a ball cage (1) for telescopic extensions with rail elements that can be moved in relation to one another in a longitudinal direction, the ball cage having at least one first holding section (2) which extends in the longitudinal direction, and openings (5) being provided in the first holding section. which are arranged next to one another in the longitudinal direction and are separated from one another by webs (6), and in which rolling elements are arranged, the ball cage having at least four rolling elements in the first holding section. In order to provide telescopic rails in which no running discontinuities or only significantly reduced running discontinuities occur even after prolonged exposure to mechanical loads, it is proposed according to the invention that the distances between at least four rolling elements that follow one another in the longitudinal direction are different from one another, with the distances between the at least four rolling elements that follow one another in the longitudinal direction each other are not an integer multiple of another distance between these four consecutive rolling elements and are not the sum of two consecutive distances between these at least four consecutive rolling elements.