Torque Sensor Sleeve Mounting via Local Shaft Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for attaching sensor holders to shafts for torque or angle of rotation sensors face challenges in ensuring a secure and permanent connection, particularly over varying temperatures and service life, which can lead to measurement errors.
Innovation Solution
The method involves locally heating the steel partial shafts to soften the plastic sleeves, allowing them to be pressed onto the shafts, creating a combined positive and non-positive connection that adapts to the shaft's geometry, eliminating the need for reinforcement and reducing the risk of cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plastic sleeves are pressed onto steel partial shafts without heating, then the connection structure is simple, but the connection reliability is insufficient and cracking may occur
Solution Approach 1:
The patent applies parameter changes by heating the steel partial shafts to elevated temperatures (e.g., 100-500°C) before pressing the plastic sleeves onto them. This temperature parameter change modifies the mechanical properties of both the steel shaft (reducing yield strength) and the plastic sleeve (increasing ductility), enabling a reliable connection without cracking while maintaining process simplicity
Solution Approach 2:
The patent implements preliminary action by pre-heating the steel partial shafts before the pressing operation. This preliminary thermal treatment prepares the shafts to accommodate the plastic sleeves during pressing, preventing cracking and ensuring connection reliability before the actual assembly occurs
2Reliability
If plastic sleeves are used without heating, then the manufacturing process is simple, but the connection may develop play over time and temperature variations
Solution Approach 1:
The patent changes the temperature parameter during manufacturing to achieve a permanent connection. By heating the steel shafts and pressing the plastic sleeves at elevated temperatures, then cooling to create interference fits, the connection becomes permanent and resistant to play development over time and temperature variations
Solution Approach 2:
The patent utilizes phase transitions by heating the steel partial shafts above room temperature, pressing the plastic sleeves during this heated state, and then allowing cooling. This thermal phase change creates the permanent interference fit that prevents play development while maintaining manufacturing simplicity
3Ease of manufacture
If the plastic sleeve geometry is simplified without heating, then the manufacturing is easier, but reinforcement is needed to prevent cracking
Solution Approach 1:
The patent applies parameter changes by heating the plastic sleeves during the pressing operation. This temperature increase enhances the plastic's ductility and reduces its yield strength, allowing the sleeves to be pressed onto the shafts without cracking while maintaining simple, unreinforced geometries that are easy to manufacture
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 approach enables a permanent, play-free connection of the torque sensor to the steering shaft, reducing the risk of measurement errors and lowering costs by eliminating the need for additional reinforcement.
Implementation Method 1
the partial shafts, usually made of steel, are heated locally to a predetermined temperature, at least in the shaft sections or areas that are used to accommodate the sleeves of the holder, which partially softens the plastic of the respective Sleeve
Implementation Method 2
after the respective shaft section has cooled down, the respective sleeve remains positively attached to the respective shaft section
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a sensor mounting and a fastening method for a rotational angle or torque sensor arrangement (5) having sleeves (9,10) made of plastic for mounting on a shaft (1;2,3), wherein the sleeves (9,10) are mounted on the shaft (1;2,3) with a form fit and force fit by a local heating and subsequent cooling of the shaft (1;2,3). The sensor arrangement is preferably a torque sensor arrangement (5) in which the shaft parts (2,3) are connected to one another via a torsion element (4) and the torque sensor arrangement (5) comprises a magnetic assembly (6) on a first sleeve (9) of the sensor mounting on the first shaft part (2) and a stator assembly (7) having a magnetic field-sensitive sensor on a second sleeve (10) of the sensor mounting on the second shaft part (3).