Ball Screw Bearing-Stop Assembly to Prevent Travel-Limit Jamming
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Solution Overview
Problem
Existing ball screw drives face issues with jamming due to the self-locking effect when a radial stop plate is used, requiring high release torque and complex assembly processes.
Innovation Solution
An integral bearing/stop element with two anti-rotation features is introduced, featuring an adjustable and fixed anti-rotation mechanism and a form-fitting connection to the spindle nut and housing, which simplifies assembly and prevents jamming by using a polygon or gear wheel anti-rotation feature and a projection or cantilever stop design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a radial stop plate is used to limit the travel of the spindle nut, then the travel limitation function is achieved, but the self-locking effect causes jamming and requires high release torque
Solution Approach 1:
Instead of using a flat axial end face that creates jamming through friction, the invention inverts the stop mechanism to use a radial stop plate with a projection that engages with a corresponding feature on the spindle nut. This radial arrangement allows the stop function to be achieved while enabling easy release by simply overcoming the radial engagement rather than breaking static friction in the axial direction.
Solution Approach 2:
The invention replaces the traditional axial friction-based stop mechanism with a radial mechanical engagement system. The projection on the radial stop plate engages with a complementary feature on the spindle nut, creating a positive mechanical stop that eliminates the self-locking effect and high release torque requirements of friction-based systems.
2Reliability
If a radial stop plate connected to the spindle is used, then the travel limitation is achieved, but the assembly process becomes complex
Solution Approach 1:
The invention merges the radial stop plate with the spindle nut into a single integrated component. The stop function is built directly into the nut structure through a projection on its outer circumference, eliminating the need for a separate radial stop plate attached to the spindle. This integration simplifies the assembly process to a single component installation while maintaining reliable travel limitation.
3Reliability
If a flange at the longitudinal end of the spindle is used as a limit stop, then the travel limitation is achieved, but the angular momentum causes jamming due to self-locking
Solution Approach 1:
The invention inverts the stop mechanism from an axial flange arrangement to a radial projection arrangement. Instead of using a flange at the end of the spindle that creates self-locking, the radial projection on the spindle nut engages with a corresponding feature, eliminating the angular momentum jamming problem while maintaining the travel limitation function.
Data Source
AI summary
A ball screw drive (10) including a threaded spindle (12) and a spindle nut (14) which at least partially coaxially encloses the threaded spindle (12) and has a stop at an axial end face (18). A multiplicity of balls can circulate in the space (16) between the threaded spindle (12) and the spindle nut (14). A radial stop element (22) is connected to the threaded spindle (12) in a force-fitting manner and adapted to interact with the complementary axial end face (18) of the spindle nut (14). A bearing element is provided for receiving a first longitudinal end of the spindle nut (12). The radial stop element (22) and the bearing element are designed in combination as an integral bearing/stop element (24) which has two anti-rotation features (26, 28).