Cam-Type Torque Wrench with Gradual Force Profile
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Solution Overview
Problem
Conventional cam-type torque wrenches face challenges in accurately detecting torque due to variations in cam shape and roller position, leading to inaccurate torque measurement and potentially hazardous sudden force changes during tightening.
Innovation Solution
A torque wrench with a cam-type torque detection mechanism featuring a static engagement cam surface, a gradually increasing torque peak cam surface, and a gradually decreasing torque cam surface, allowing for accurate torque detection and smooth operation by transitioning through kinetic friction and reducing sudden force releases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional cam-type torque detection mechanism is used, then torque detection is achieved, but measurement precision deteriorates due to variations in cam shape and roller position
Solution Approach 1:
The cam mechanism is designed with a predetermined cam surface profile that is calculated in advance to compensate for friction variations. The roller follower is pre-positioned to engage the cam surface at specific points, ensuring that the torque detection accounts for friction effects before they occur during operation.
Solution Approach 2:
The invention changes the geometric parameters of the cam surface to optimize torque detection. By carefully designing the cam profile with specific curvature radii and transition points, the system compensates for friction variations and achieves more accurate torque measurements despite variations in roller position.
2Device complexity
If the cam surface has abrupt transitions, then torque detection is simplified, but object-generated harmful factors increase due to sudden force changes
Solution Approach 1:
The cam surface is designed with continuous curved transitions instead of abrupt angular changes. The cam profile includes gradually transitioning curved surfaces that guide the roller follower smoothly, eliminating sudden force changes while maintaining effective torque detection functionality.
3Measurement precision
If the roller member engages the cam surface with static friction, then torque detection is achieved, but measurement precision deteriorates due to transition to kinetic friction
Solution Approach 1:
The cam surface is designed with a preliminary engagement phase where the roller follower engages the cam surface in a controlled manner. The cam profile includes a lead-in curved surface that guides the roller into proper engagement, ensuring smooth transition from static to kinetic friction and accurate torque detection.
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
Enables high-accuracy torque detection and safe operation by maintaining a gradual force reduction, reducing the risk of injury and improving user experience during tightening.
Implementation Method 1
a resilient member (14) to actuate the roller member (18)
Implementation Method 2
The roller member (18) is subjected to the tightening force
Data Source
Figure 1(a)~1(c)
Figure 2(a)~2(d)
Figure 3(a)~3(b)
AI summary
A torque wrench equipped with a cam-type torque detection mechanism is provided which is capable of detecting a torque with high accuracy, providing a non-unusual-feeling of handle operation after torque has been detected, and enabling tightening of fastened members such as bolts with safety. In a torque wrench equipped with the cam-type torque detection mechanism, a cam portion (27) formed on the outer circumference of a tubular cam (22) includes: a static engagement cam surface (27a) with which a roller member (18) in a static status engages in a non-operated status; a gradually increasing torque peak cam surface (27b) which is connected to the static engagement cam surface (27a) and with which the roller member (18) is brought into contact while moving to thereby gradually increase the torque peak value; a cam top surface (27c) forming the cam top portion continued to the gradually increasing torque peak cam surface (27b); a gradually decreasing torque cam surface (27d) for gradually decreasing a plus torque to the roller member (18) to zero; and a minus torque cam surface (27e) for imparting a minus torque to the roller member (18) having passed over the gradually decreasing torque cam surface (27d).