US 12,390,070 B2
Heating, ventilation, and air conditioning (HVAC) air duct cleaning system
James Kevin McCoy, Garland, TX (US); Jared A. Smothermon, Lucas, TX (US); and Jeffrey Alan Garrett, Allen, TX (US)
Assigned to Rotobrush International LLC, Grapevine, TX (US)
Filed by Rotobrush International LLC, Grapevine, OK (US)
Filed on May 15, 2024, as Appl. No. 18/665,306.
Application 18/665,306 is a continuation of application No. 17/683,666, filed on Mar. 1, 2022, granted, now 12,011,140.
Prior Publication US 2024/0298861 A1, Sep. 12, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. A47L 9/28 (2006.01); A47L 9/04 (2006.01); B08B 9/045 (2006.01); F24F 11/30 (2018.01); G05B 15/02 (2006.01)
CPC A47L 9/2842 (2013.01) [A47L 9/0466 (2013.01); A47L 9/2831 (2013.01); A47L 9/2857 (2013.01); B08B 9/045 (2013.01); F24F 11/30 (2018.01); G05B 15/02 (2013.01); B08B 2209/04 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An improved control method for air handling duct cleaner, comprising:
receiving, by a control circuit, a real-time signal indicating an amount of current being drawn into an electric motor of an air handling duct cleaner, while controlling a voltage to the electric motor to achieve a target motor speed in a first mode of control;
determining, by the control circuit, from the signal a rate of change over time of the current being drawn into the electric motor; and
responsive to the rate of change exceeding a first threshold, discontinuing, by the control circuit, the first mode of control and enabling a second mode of control, wherein the second mode of control comprises applying a hold voltage to the electric motor to prevent reverse electromotive force from being induced into the motor from a mechanical release of a bound up drive cable mechanically driven by the electric motor.