Internal-Deflector Ball Screw for Compact Ball Recirculation
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Solution Overview
Problem
Ball screw drives with external deflectors increase the external diameter and volume of components, making compact integration difficult, and external transfer channels can impede integration in drive systems, while existing internal deflectors have design limitations.
Innovation Solution
A ball screw drive with an internal deflector featuring a transfer channel oriented toward the central axis, using oblique core halves and a carrier element with tongue-shaped blades to guide balls, reducing the external diameter and enhancing assembly efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an external deflector is used to guide balls radially outwardly into the spindle nut, then the ball return guide can be implemented, but the external diameter and volume of the component increase
Solution Approach 1:
The patent inverts the conventional external deflector approach by implementing an internal deflector that guides balls radially inwardly into the threaded spindle. This inversion allows the transfer channel to be accommodated within the existing spindle structure, eliminating the need for external additions and thus reducing the overall component volume while maintaining the ball return function.
Solution Approach 2:
The internal deflector design nests the transfer channel within the threaded spindle's internal cavity. The deflector and transfer channel are integrated into the hollow cylinder structure of the spindle, creating a nested configuration where the ball return guide is contained within the existing component boundaries rather than adding to them.
2Productivity
If an external transfer channel is attached to the spindle unit, then ball recirculation is enabled, but compact integration in drive systems is impeded
Solution Approach 1:
The patent merges the transfer channel function with the threaded spindle structure itself. The internal deflector and transfer channel are integrated into the spindle's hollow cylinder, combining the ball return guide function with the existing rotational component. This eliminates separate external attachments and simplifies the overall drive system integration.
Solution Approach 2:
The threaded spindle is designed with multi-functionality: it serves both as the rotational drive element with ball race and as the housing for the internal deflector and transfer channel. The hollow cylinder structure performs dual purposes - containing the ball race on its outer surface and accommodating the ball return guide within its cavity.
3Volume of moving object
If the threaded spindle is designed as a hollow cylinder with internal deflector, then compact size is achieved, but the internal cavity must be filled to maintain structural integrity
Solution Approach 1:
The patent segments the internal cavity filling into two functional parts: a core element that provides structural support and fills the majority of the hollow cylinder cavity, and an internal deflector that provides the ball guide function. This segmentation allows the structural and functional requirements to be met separately, with the core providing strength and the deflector enabling compact ball recirculation.
Solution Approach 2:
The core acts as an intermediary element between the hollow cylinder and the internal deflector. It fills the internal cavity to provide structural integrity and serves as the mounting substrate for the internal deflector, mediating between the structural requirements of the hollow cylinder and the functional requirements of the ball return guide.
Data Source
AI summary
A ball screw drive having a threaded spindle, a spindle nut and balls which circulate in a helical ball race located therebetween. Two ball deflectors engage in the ball race and a transfer channel extends therebetween that together with part of the ball race form a closed recirculation track. The ball return guide is an internal deflector. The threaded spindle includes a radially external hollow cylinder with a central symmetrical internal cavity and a cylindrical core filling this cavity. The cylindrical core is formed of first and second core halves. The transfer channel is arranged in the common separating surface of the core halves, which are designed as oblique halves, the common separating surface thereof forming a plane which intersects the central axis of the core only at one point. The ball screw drive can be used in a brake booster system, a wheel brake or generally as an actuator.