Ultrasonic-Welded Steering Coupling for Higher Torque Transfer
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Solution Overview
Problem
Existing motor vehicle steering systems with serrated worm clutches have limitations in torque transmission capacity, manufacturing complexity, and susceptibility to cracks, leading to short service life and high production costs.
Innovation Solution
A motor vehicle steering system utilizing a thermoplastic coupling part connected to shafts via ultrasonic welding, where the shafts feature knurling for a positive and material-locking connection, eliminating the need for injection molding inserts and preheating, thus simplifying manufacturing and enhancing durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If serrated worm clutch with internal teeth is used, then torque transmission capacity is limited, but manufacturing is simpler
Solution Approach 1:
The patent replaces the mechanical tooth-root load-carrying connection with an ultrasonic welding process that creates a material-locking connection. The thermoplastic coupling part is welded directly to the shaft, eliminating the need for serrated worm clutch teeth and internal gear teeth, thereby increasing torque transmission capacity while simplifying the manufacturing process.
Solution Approach 2:
The patent changes the connection method from mechanical interlocking (serrations and internal teeth) to ultrasonic welding with material locking. This parameter change in the joining process enables higher torque transmission by creating a more robust material-level connection rather than relying on gear tooth engagement.
2Ease of manufacture
If conventional injection molding inserts with press connection are used, then manufacturing is more complex, but connection strength is adequate
Solution Approach 1:
The patent extracts and eliminates the injection molding inserts and preheating steps from the manufacturing process. By using ultrasonic welding directly on the thermoplastic coupling part, the process removes unnecessary intermediate components and steps, simplifying manufacturing while maintaining or improving connection reliability through the material-locking ultrasonic weld.
3Strength
If high-frequency mechanical vibration is introduced for ultrasonic welding, then connection strength increases, but energy consumption increases
Solution Approach 1:
The patent uses periodic high-frequency mechanical vibrations (ultrasonic range) during the welding process to create strong material-locking connections. The periodic vibration at ultrasonic frequencies generates localized heat and friction that melts and fuses the thermoplastic material to the shaft, creating strong bonds with controlled energy input.
4Productivity
If thermoplastic coupling part is used without preheating, then manufacturing time is reduced, but material bonding may be insufficient
Solution Approach 1:
The patent uses mechanical vibration in the ultrasonic range to generate localized heat at the bonding interface during the welding process. This eliminates the need for preheating the entire thermoplastic coupling part, reducing production cycle time while ensuring adequate bonding quality through controlled localized heating and material locking during the vibration welding process.
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 enables higher torque transmission with improved durability and reduced manufacturing complexity, avoiding stress on components and preventing damage from incorrect thread positioning, while achieving a material and form-fitting connection between the shafts and coupling parts.
Implementation Method 1
the corresponding coupling part is made of a thermoplastic material and at least one of the shafts is connected to the corresponding coupling part by means of ultrasonic welding
Implementation Method 2
introduction of a high-frequency mechanical vibration in the ultrasonic range into the shaft
Implementation Method 3
when the high-frequency mechanical vibration is introduced into the shaft, the corresponding coupling part is partially heated and plasticized
Implementation Method 4
Plasticization refers to the transition from a solid to a deformable or flowable state in order to facilitate or enable further processing
Implementation Method 5
after cooling, a positive and material-locking connection is created between the coupling part and the shaft
Data Source
Figure 1~3
Figure 4~6
Figure 7~9
AI summary
The invention relates to a motor vehicle steering mechanism comprising an electric motor (9) with a motor shaft (20), further comprising a worm gear (11) with a worm gear shaft (12), and comprising a coupling member (15) which connects the two shafts (20, 12) to allow torque to be transmitted, the coupling member (15) having a first coupling part (14) and a second coupling part (21), each of which is joined to one of the shafts (20, 12), at least one of the shafts (20, 12) being joined to the associated coupling part (21, 14) using ultrasonic welding.