Differential Jam-Proof Sensor for Shredder Throat
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Solution Overview
Problem
Shredders often jam when fed more papers than their stated capacity, leading to user frustration and difficulty in clearing jams, as existing thickness sensing technologies may not effectively prevent severe jams caused by overly thick objects.
Innovation Solution
A shredder with a differential jam-proof sensor system that uses two opposing contact members to detect the thickness of articles from both sides of the throat, preventing the motor from driving the cutter elements if the thickness exceeds a predetermined maximum, and featuring a controller that performs predetermined operations such as stopping the motor or activating an alarm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single thickness sensor is used to detect article thickness, then the device complexity is reduced, but the measurement precision and reliability of thickness detection deteriorates due to inability to account for article positioning variations
Solution Approach 1:
The thickness detection function is segmented into two independent contact members positioned at different locations within the throat. Each contact member independently measures thickness at its specific position, and the controller combines these measurements to determine the overall article thickness, thereby improving measurement precision without requiring a single complex sensor system
Solution Approach 2:
Different contact members are positioned at specific locations within the throat to detect thickness at different positions. This allows the system to account for variations in article positioning and thickness distribution across different locations, improving the overall accuracy of thickness detection
2Productivity
If the shredder accepts more papers than stated capacity, then the productivity increases, but the reliability deteriorates due to increased likelihood of jams
Solution Approach 1:
The thickness sensor system performs preliminary detection of article thickness before the shredding operation begins. By measuring the actual thickness of the article stack and comparing it against the predetermined maximum thickness, the system can prevent the motor from operating on excessively thick articles, thereby avoiding jams before they occur
Solution Approach 2:
The controller receives feedback from the thickness sensors about the actual article thickness and uses this information to control motor operation. When the detected thickness exceeds the predetermined maximum, the controller prevents motor operation, creating a closed-loop system that adapts to actual loading conditions and prevents jams
3Reliability
If the motor is prevented from operating on thick articles, then the reliability improves by preventing jams, but the productivity decreases due to fewer articles that can be shredded
Solution Approach 1:
The system changes the operational parameter of the motor based on detected article thickness. When thickness is within acceptable limits, the motor operates at normal speed for high productivity. When thickness exceeds the threshold, the motor operation is prevented, sacrificing temporary productivity to maintain reliability and prevent jams
Data Source
AI summary
Disclosed is a shredder including a detector having a first contact member on one side of the shredder's throat and a second contact member on the other side. The contact members extend into the throat and are independently moveable relative to one another to enable insertion of an article into the throat. The article can move the contact members relative to one another by a combined amount. The shredder may prevent its motor from driving its cutter elements if it determines that the combined amount of independent relative movement correlates to a thickness that is equal to or greater than a predetermined maximum thickness. In an embodiment, the contact members may include binary switches. The contact members aid in controlling and/or reducing flutter and wrinkles when articles are fed into the shredder.