Overload control device for rotating machinery
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Solution Overview
Problem
Industrial floor scraping machines with rotating discs and blades pose a risk to operators due to sudden torque transfers when encountering cracks or expansion joints, as the motor continues to transmit power during stops, leading to potential injuries from repeated impacts.
Innovation Solution
An overload control device that senses current spikes exceeding a user-adjustable threshold, rapidly cutting power to the motor via a relay, incorporating a delay to account for motor start-up and requiring a manual reset to prevent further torque transmission to the operator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor continues to transmit power during sudden stops, then the motor maintains operational capability, but large torque is transferred to the operator causing potential injuries
Solution Approach 1:
The overload control device applies preliminary anti-action by detecting current spikes that indicate sudden stops and immediately cutting power to the motor before harmful torque can be transmitted to the operator. The device anticipates the harmful effect and prevents it by interrupting power supply in response to overload conditions.
2Object-affected harmful factors
If power is cut immediately upon detecting overload, then operator safety is enhanced, but motor start-up capability may be affected
Solution Approach 1:
The overload control device incorporates a time delay feature that allows motor start-up current spikes to pass without triggering shutdown, while still providing immediate protection against harmful overload conditions. This preliminary action distinguishes between normal start-up transients and dangerous overload conditions, ensuring both motor operability and operator safety.
3Object-affected harmful factors
If manual reset is required after overload, then prevention of repeated torque transfers is achieved, but operational continuity is reduced
Solution Approach 1:
The overload control device uses feedback by requiring manual reset after an overload event, which prevents repeated torque transfers to the operator while allowing operational continuity when conditions are normal. The feedback mechanism ensures the operator is aware of the overload condition and can reset the system when safe to do so.
Data Source
AI summary
An overload control device for use with a floor machine having an electric motor is disclosed. The overload control device can include a power input and a power output connectable to the electric motor. The device can include a load detector, a current sensor operative to sense a current value supplied to the motor via the power output, and a cutoff relay interconnecting the power input and the power output. The cutoff relay being operative to supply power from the power input to the power output when activated, and interrupt power when deactivated. A controller receives a load present indication from the load detector and activates the cutoff relay if a load is present. The controller receives a current value from the current sensor, determines if the current value is greater than a threshold value, and deactivates the cutoff relay when the current value is greater than the threshold value.