Ball Screw Suspension Assembly With Spline Fit for Axis Alignment
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Solution Overview
Problem
Suspension devices with ball screws face axis deviation issues due to torque transmission, leading to loosening of fixing members and subsequent load application, which deteriorates the parts.
Innovation Solution
A suspension device with a spline fitting structure in the insertion portion of the ball screw and fastening member, preventing torque transmission to the fixing member and maintaining axis alignment, thereby suppressing axis deviation and associated loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a fixing member is used to fix the ball screw to the fastening member, then the ball screw is securely fixed, but the torque from ball screw rotation is transmitted to the fixing member causing it to loosen and the ball screw axis to deviate
Solution Approach 1:
The insertion portion is segmented into multiple spline fitting structures distributed around the circumference, separating the torque transmission function from the axial fixing function. The spline fittings engage the ball screw's outer peripheral surface at multiple points, distributing the torque load and preventing concentration on the fixing member.
Solution Approach 2:
The spline fitting structure acts as an intermediary between the ball screw and the fastening member, providing a dedicated torque transmission path through the engagement of protrusions and grooves. This intermediary structure prevents direct torque transmission to the fixing member while maintaining secure connection.
2Ease of operation
If the ball screw rotates to transmit motion, then damping function is achieved, but torque is generated that loosens the fixing member
Solution Approach 1:
The torque transmission function is extracted from the fixing member and assigned to the dedicated spline fitting structure. The protrusions and grooves of the spline fittings specifically engage to transmit torque, while the fixing member focuses solely on providing axial clamping force, separating the two functions.
Solution Approach 2:
The spline fitting structure is pre-formed on both the ball screw and fastening member with complementary protrusions and grooves, creating a predetermined torque transmission path before operation begins. This preliminary structuring prevents torque-induced loosening during operation.
3Ease of manufacture
If a simple insertion structure is used, then assembly is easy, but the ball screw axis deviates under torque load
Solution Approach 1:
The spline fitting structure employs asymmetric protrusions and grooves that mate together in a specific orientation, providing inherent alignment guidance during assembly. The asymmetric geometry ensures correct positioning while maintaining ease of assembly through simple insertion motion.
Solution Approach 2:
The solution adds a circumferential dimension to the connection by distributing multiple spline fittings around the ball screw's circumference. This multi-point engagement in the circumferential direction provides rotational stability and axis alignment precision while maintaining simple axial insertion for assembly.
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
The spline fitting structure effectively prevents axis deviation and load application, enhancing the stability and durability of suspension device components.
Implementation Method 1
an insertion portion, where the ball screw is inserted into the fastening member, is provided with a fitting portion where the ball screw fits the fastening member, the fitting portion having a spline fitting structure
Implementation Method 2
a ball screw housed in the cylinder portion, a fastening member that supports the ball screw with the ball screw being inserted through the fastening member and is attached to an end part of the cylinder portion
Data Source
AI summary
A suspension device includes a damper. The damper includes: an outer cylinder; a ball screw housed in the outer cylinder; a fastening member that supports the ball screw inserted therethrough and is attached to an end part of the outer cylinder; and a fixing member that is attached to an end part of the ball screw and fixes the ball screw to the fastening member. An insertion portion, where the ball screw is inserted into the fastening member, is provided with a fitting portion where the ball screw fits the fastening member, and the fitting portion has a spline fitting structure.