US 12,320,373 B2
System and methods for controlled lowering and lifting of a load
Michael Berne Rannow, Eden Prairie, MN (US); and Vishal Vijay Mahulkar, Eden Praire, MN (US)
Assigned to DANFOSS A/S, Nordborg (DK)
Filed by DANFOSS POWER SOLUTIONS II TECHNOLOGY A/S, Nordborg (DK)
Filed on Nov. 11, 2022, as Appl. No. 18/054,654.
Application 18/054,654 is a continuation of application No. 16/740,682, filed on Jan. 13, 2020, granted, now 11,566,399.
Application 16/740,682 is a continuation of application No. 14/106,112, filed on Dec. 13, 2013, granted, now 10,533,304, issued on Jan. 14, 2020.
Claims priority of provisional application 61/737,607, filed on Dec. 14, 2012.
Prior Publication US 2023/0075340 A1, Mar. 9, 2023
Int. Cl. F15B 19/00 (2006.01); E02F 9/24 (2006.01)
CPC F15B 19/005 (2013.01) [E02F 9/24 (2013.01); F15B 2211/3057 (2013.01); F15B 2211/427 (2013.01); F15B 2211/7053 (2013.01); F15B 2211/8752 (2013.01)] 7 Claims
OG exemplary drawing
 
1. A hydraulic system, comprising:
a) a hydraulic actuator for supporting a load;
b) a control valve in fluid communication with the hydraulic actuator;
c) a controller for operating the control valve, the controller being configured to operate the control valve in a normal operational mode and a safe operational mode:
i) the normal operational mode including at least a first algorithm for operating the control valve in a load lowering operation or a load lifting operation; and
ii) the safe operational mode including disabling the first algorithm and sending a pulse width modulation (PWM) current from the controller to the control valve, the PWM current having a duty ratio; and
d) a machine user interface configured to provide an input to the controller to allow an operator to adjust the PWM current duty ratio to lower the load or to lift the load supported by the hydraulic actuator,
wherein the PWM current has a lower limit that is below a value required to move the control valve and has an upper limit that is above the value required to move the control valve; and
wherein the controller is configured to:
detect when a new valve has been added to the hydraulic system; and
automatically switch to operate in the safe operational mode in response to the controller detecting the new valve.