Ball Screw Suspension Assembly for Greater Coil Spring Contraction
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Solution Overview
Problem
The suspension device described in JP 2010-228579A has complex assembly requirements and limited coil spring contraction, making assembly difficult and potentially hindering the effective use of the suspension system.
Innovation Solution
The suspension device incorporates an upper and lower shell with a ball screw mechanism, a bearing unit, and an electric motor, allowing for easier assembly and increased coil spring contraction through a stepped section design that enables the ball nut and inner tube to pass through the upper shell, facilitating the assembly process and maintaining the contractible amount of the coil spring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ball nut and inner tube are supported by the casing of the electromagnetic motor, then the assembly structure is stable, but the assembly process becomes complex and time-consuming
Solution Approach 1:
The suspension device is divided into separate functional modules: the upper support with its stepped section, the ball screw mechanism, and the electromagnetic motor assembly. This segmentation allows each component to be assembled and positioned independently, reducing overall assembly complexity and time while maintaining structural stability through defined mounting interfaces.
Solution Approach 2:
The stepped section of the upper support acts as an intermediary structure that facilitates the passage of the ball nut and inner tube. This intermediate geometric feature enables components to be positioned and secured without requiring complex integration with the motor casing, thereby simplifying the assembly process while ensuring reliable support.
2Length of moving object
If the lower retainer is installed below the outer tube to increase coil spring contraction, then the contractible amount increases, but the layout may be hindered
Solution Approach 1:
The stepped section of the upper support utilizes the radial dimension to create clearance space, allowing the ball nut and inner tube to pass through while maintaining proper spacing. This dimensional approach enables increased coil spring contraction without requiring the lower retainer to be positioned below the outer tube, thus avoiding layout complications while achieving the desired contraction range.
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 design simplifies assembly, allows for easier handling of components, and enhances the contractible amount of the coil spring, improving the overall functionality and ease of use of the suspension system.
Implementation Method 1
a ball screw mechanism converts rotation of the motor shaft to linear motion in the axial direction of the screw rod
Implementation Method 2
the coil spring is held between an upper retainer and a lower retainer... By causing the entire length of the upper support and the outer tube to contract, the coil spring elastically contracts
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Construction of a suspension device 1 is achieved that allows for easy assembly, and by which the contractible amount of a coil spring thereof can be easily maintained. A bearing unit 5 is arranged between a part on the other side in the axial direction of a ball screw shaft 4 and an upper shell 2, and by a side surface on one side in the axial direction of a pressing plate 35 of the bearing unit 5 that is prevented from rotating with respect to the upper shell 2 coming in contact with a side surface on the other side in the axial direction of a flange section 9 of the upper shell 2 through a stopper holder 50, the bearing unit 5 rotatably supports the ball screw shaft 4 with respect to the upper shell 2. The circumscribed circle diameter of a ball nut 6 and inner tube 61 is less that the inner diameter dimension of the flange section 9. In other words, during assembly of the suspension device 1, an intermediate assembly 124 that includes the ball nut 6 and inner tube 61 can pass through the inner side in the radial direction of the flange section 9 of the upper shell 2.