Profiled Cam Lock Lever for Torque Wrench Dial Stability
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Solution Overview
Problem
Existing torque wrenches with fixed pivot points require significant force to operate and often result in rapid release of spring tension, leading to unintended dial setting changes and potential user injury due to insufficient spring tension in the locked position.
Innovation Solution
A split beam style torque wrench with a profiled cam lock lever featuring an off-center pivot pin and decreasing radius cam profile, which increases spring tension in the locked position and reduces the effort needed to operate the lever, minimizing unintended dial setting changes and user impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed pivot point is used on the lever, then the lever structure is simple, but significant force is required to operate the lever and spring tension is insufficient in the locked position
Solution Approach 1:
The patent transforms the fixed pivot point into a moving pivot point that travels along a cam profile curve during lever operation. This dynamic mechanism allows the pivot point to change position, creating varying mechanical advantages throughout the lever's range of motion. The moving pivot reduces the force required to operate the lever while maintaining simplicity in the overall lever structure.
2Ease of operation
If the lever shape applies maximum tension through the spring at halfway position, then the lever can be operated, but the lever flips over rapidly causing sharp impact to user's hand or fingers
Solution Approach 1:
The cam profile is designed to control the sequence of events during lever operation. By preliminary positioning the pivot point and controlling the rate of spring tension application, the system prevents sudden releases of stored energy. The cam profile ensures that spring tension builds and releases in a controlled manner, eliminating the rapid flipping motion that causes harmful impacts to the user's hand.
3Ease of operation
If spring tension is insufficient when the lever is in the locked position, then the lever is easy to operate, but the dial moves and changes the torque setting undesirably during repeated use
Solution Approach 1:
The patent utilizes the cam profile to dynamically change the mechanical parameters of the system during operation. By varying the pivot point position along the cam curve, the system achieves different force multiplication ratios. In the locked position, the cam profile parameters are optimized to provide sufficient spring tension for reliable dial retention, while during operation, the parameters change to reduce the force required by the user.
4Ease of operation
If a rounded corner with decreasing radius cam profile is used, then the force needed to operate the lever is reduced, but the complexity of the lever profile increases
Solution Approach 1:
The patent employs a rounded corner with a decreasing radius cam profile instead of straight lines or constant curvature arcs. This curved geometry smoothly guides the pivot point along an optimized path, reducing the force required to operate the lever. The decreasing radius creates a natural cam action that provides mechanical advantage throughout the motion, while the rounded shape maintains manufacturing simplicity compared to complex multi-segment profiles.
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 ensures sufficient spring tension is maintained in the locked position, preventing unintentional torque setting changes and reducing the force required to operate the lever, thereby enhancing user safety and tool longevity by smoothing the operation and reducing rapid release velocity.
Implementation Method 1
maintain a dial setting (also referred to as a torque setting) of the tool through spring tension of a bias member applied to the adjustment knob
Implementation Method 2
The off-center pivot pin increases a distance an end of the bias member is deflected when the locking lever is in the locked position, and thereby increases an amount of force applied to the adjustment knob
Implementation Method 3
The cam profile reduces an amount of force or effort needed to operate the lock lever (compared to prior tools), while also ensuring that sufficient spring tension is applied to the adjustment knob when the lock lever is in the locked position
Data Source
AI summary
A torque wrench with a profiled cam lock lever that is movable between locked and unlocked positions over an adjustment knob of the tool. The lock lever includes an off-center pivot pin and a decreasing radius on a cam profile of the lock lever (rounded corner that contacts a housing of the tool when the lock lever is moved between the locked and unlocked positions). The off-center pivot pin increases an amount of force applied to the adjustment knob when the lock lever is in the locked position to minimize and/or prevent unintentional movement of the adjustment knob. The cam profile reduces an amount of force or effort needed to operate the lock lever and decreases rapid release of the lock lever as over center action is reached.