US 12,011,140 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, TX (US)
Filed on Mar. 1, 2022, as Appl. No. 17/683,666.
Prior Publication US 2023/0277025 A1, Sep. 7, 2023
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)] 24 Claims
OG exemplary drawing
 
1. An improved control method for air handling duct cleaner, comprising:
receiving, by a system controller, a real-time measurement 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 system controller, a rate of change over time from the current measurement; and
responsive to the rate of change of current measurement exceeding a first threshold, discontinuing, by the system controller, 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.