Roller Screw Actuator Preload Setting in Split Steering Housing
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Solution Overview
Problem
Existing methods for setting and adjusting the axial preload force of roller screw drives in motor vehicle steering systems, such as rear-wheel steering, are complex and difficult to modify after installation, requiring significant space and not cost-effective for automotive applications.
Innovation Solution
A method involving a split housing with axially spaced bearings and an adjusting nut that is screwed into a threaded bore, allowing for precise measurement and setting of the axial preload force by adjusting the screwing depth of the nut, which is then secured using a screw lock, enabling reliable and space-efficient axial preload adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex measures such as spacers or multiple screw sleeves are used to set axial preload force, then the preload can be adjusted, but the device complexity increases and more space is required
Solution Approach 1:
The patent extracts the preload adjustment function from complex multi-component assemblies (spacers, multiple screw sleeves) and concentrates it into a single integrated adjusting nut that threads directly onto the thrust rod, simplifying the overall structure while maintaining adjustment capability
Solution Approach 2:
The adjusting nut serves multiple functions: it sets the axial preload force, positions the roller screw drive axially, and provides a mounting interface for the thrust rod, eliminating the need for separate components for each function
2Manufacturing precision
If complex measures such as spacers or multiple screw sleeves are used to set axial preload force, then the preload can be adjusted, but the space requirement increases
Solution Approach 1:
The patent removes unnecessary intermediate components (spacers, multiple screw sleeves) that occupy valuable space within the planetary roller carrier, retaining only the essential adjusting nut that achieves the same preload function in a more compact manner
Solution Approach 2:
The adjusting nut is designed to thread directly onto the thrust rod and accommodate the roller screw drive components within its structure, creating a nested arrangement that minimizes the overall volume occupied by the preload adjustment mechanism
3Manufacturing precision
If the roller screw drive is installed with bearings in a split housing, then the axial preload can be set, but the adjustment becomes difficult after installation
Solution Approach 1:
The housing is divided into two separable halves that can be removed independently, allowing the thrust rod and adjusting nut to remain in place while providing access to the roller screw drive for preload adjustment without requiring complete disassembly of the housing
Solution Approach 2:
The adjusting nut is designed with a thread connection to the thrust rod that allows for preliminary positioning and preload setting before final housing assembly, enabling easy adjustment during installation and maintenance while ensuring precise preload force
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 method allows for reliable and simple setting of the axial preload force, minimizing play and ensuring correct operation of the actuator, while being cost-effective and space-efficient, particularly suitable for automotive applications like rear-wheel steering systems.
Implementation Method 1
An adjusting nut (10) penetrated by the thrust rod (7) is screwed into a thread (11) of the first housing part (8)
Implementation Method 2
roller screw drive (3), which converts a rotational movement into a translational movement
Implementation Method 3
roller screw drive (3), which is rotatably mounted in the housing (2) by means of bearings (4, 5) arranged axially spaced apart from one another
Data Source
AI summary
A method is disclosed for setting an axial preload force of a roller screw drive rotatably mounted in a housing. The housing is split transversely into a first and a second housing part. The roller screw drive is inserted with two axially spaced bearings into the second housing part. An axial preload force is applied which is transmitted from the first bearing via the roller screw drive to the second bearing. An axial load spacing between the bearing supporting surface of the first bearing and a second housing edge of the second housing part is measured. An adjusting nut is screwed into the first housing part until an axial adjustable spacing is the same size as the measured axial load spacing. The adjusting nut is then secured in place in the first housing part, and the two housing parts are connected to one another.