Steering Shaft Elastic Rollers and Steel Balls Torque Transmission
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Solution Overview
Problem
Telescoping steering shafts for motor vehicles face challenges in minimizing play and stick-slip effects during torque transmission, which affect the steering feel and noise levels, and existing solutions do not adequately address these issues for all torque ranges.
Innovation Solution
A steering shaft design featuring a sliding sleeve with elastic rollers and stiff steel balls, where elastic rollers with helical slots and C-shaped cross-sections provide smooth torque transmission at low torques, and stiff steel balls take over at higher torques, ensuring play-free operation and reduced stick-slip effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If elastic rollers with helical slots are used for torque transmission, then smooth operation and reduced stick-slip effect are achieved, but play in torque transmission increases at higher torques
Solution Approach 1:
The torque transmission system is segmented into two distinct components: elastic rollers for low-torque smooth operation and stiff steel balls for high-torque play-free operation. This segmentation allows each component to be optimized for its specific torque range, resolving the contradiction between smooth operation and play-free transmission.
Solution Approach 2:
The system changes the stiffness parameter of the rolling elements based on torque magnitude. Elastic rollers provide compliance and smooth operation at low torques, while stiff steel balls provide rigidity and play-free transmission at high torques. This parameter change resolves the contradiction by adapting the transmission characteristics to the operating conditions.
2Reliability
If stiff rolling elements are used for torque transmission, then play-free operation is achieved, but stick-slip effect increases during telescoping
Solution Approach 1:
The system changes the stiffness parameter of the rolling elements based on torque magnitude. Elastic rollers provide compliance and smooth operation at low torques, while stiff steel balls provide rigidity and play-free transmission at high torques. This parameter change resolves the contradiction by adapting the transmission characteristics to the operating conditions.
Solution Approach 2:
The elastic rollers act as an intermediary between the inner and outer spindles during low-torque conditions, providing a compliant connection that eliminates stick-slip effects. During high-torque conditions, the stiff steel balls take over as the intermediary, providing play-free rigid transmission. This intermediary mechanism resolves the contradiction between smooth operation and play-free transmission.
3Ease of operation
If sliding sleeve is used to reduce friction, then smooth telescoping is achieved, but torque transmission play increases
Solution Approach 1:
The system segments the friction reduction function from the torque transmission function. The sliding sleeve handles friction reduction for smooth telescoping, while separate rolling elements (elastic rollers and steel balls) handle torque transmission. This segmentation allows the sliding sleeve to provide smooth telescoping without compromising torque transmission rigidity.
Solution Approach 2:
The sliding sleeve acts as an intermediary that reduces friction between the inner and outer spindles during telescoping motion. Meanwhile, the rolling elements serve as intermediaries for torque transmission. This dual intermediary system resolves the contradiction by separating the friction reduction function from the torque transmission function.
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 solution achieves seamless torque transmission across all torque ranges without perceived play, enhancing steering feel and reducing noise and stick-slip occurrences, thereby improving the overall performance and ergonomics of the steering system.
Implementation Method 1
at least one elastic roller made of an elastic plastic is accommodated in the receptacle, the elastic roller having a slot extending in the direction of the roller, which is designed helically in the sense of a quarter screw pitch
Implementation Method 2
the sliding sleeve having at least one recess for receiving at least one rolling element engaging with the inner spindle and the outer spindle for torque transmission
Data Source
Figure 1~4
Figure 5~12
AI summary
The present invention relates to a steering shaft (1) for a motor vehicle, comprising an inner spindle (2), an outer spindle (3) which is telescopic relative thereto, and a sliding sleeve (4) which is arranged between the inner spindle (2) and the outer spindle (3), wherein the sliding sleeve (4) has at least one recess (44) for accommodating at least one rolling element (5) which engages with the inner spindle (2) and the outer spindle (3) for the purpose of transmitting torque, wherein the sliding sleeve (4) has at least one opening (40) for accommodating at least one elastic roller (6) which is arranged between the inner spindle (2) and the outer spindle (3) for the purpose of transmitting torque.