US 12,216,443 B2
System and method for controlling a latching relay failsafe
Zachary R. Wright, Wildwood, MO (US); and Ted W. Sunderland, Washington, MO (US)
Assigned to Parker-Hannifin Corporation, Cleveland, OH (US)
Appl. No. 17/788,078
Filed by Parker-Hannifin Corporation, Cleveland, OH (US)
PCT Filed Feb. 26, 2021, PCT No. PCT/US2021/019850
§ 371(c)(1), (2) Date Jun. 22, 2022,
PCT Pub. No. WO2021/173955, PCT Pub. Date Sep. 2, 2021.
Claims priority of provisional application 62/982,316, filed on Feb. 27, 2020.
Prior Publication US 2023/0048352 A1, Feb. 16, 2023
Int. Cl. G05B 19/042 (2006.01)
CPC G05B 19/0428 (2013.01) [G05B 2219/24125 (2013.01); G05B 2219/24139 (2013.01); G05B 2219/2614 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A control circuit, comprising:
a relay including at least a first coil terminal and a second coil terminal;
a first monitoring circuit having a first node coupled to a power supply input configured to activate the first coil terminal in the event of a power loss;
a microcontrol unit (MCU), wherein, under a normal operation, the MCU operates to constantly reinforce a state of the relay;
a watchdog circuit communicative with the MCU, wherein the watchdog circuit is configured to activate the first coil terminal in the event that the MCU stops communication with the watchdog circuit; and
a power loss activation circuit that is electrically connected to the first monitoring circuit to provide backup power during a power loss;
wherein the watchdog circuit comprises of a rising edge detector, a watchdog timer, a falling edge detector, and a pulse generator.