US 5,490,442 A · Safety circuit for a servo-hydraulic regulating system

Abstract

A safety circuit for a servo-hydraulic regulating system for the hydraulic control and actuation of load units, such as operating tools on utility vehicles and agricultural machines. The controlling of the load unit is effected via a proportional valve which is actuated in dependence upon a pair of output signals of a measuring bridge in such a way that, in the event of a balanced measuring bridge, it assumes a neutral setting in which the operating line running to the load unit or emanating from the load unit is blocked. In order to prevent the lifting gear from executing a regulating reaction if the measuring bridge is out of tune when the servo-hydraulic regulating system is switched on, a safety valve arrangement is provided in the operating line. Depending on at least one control signal determined by the setting of the proportional valve, when the regulating system is switched on, the operating line is blocked until, via the at least one control signal, the balance of the measuring bridge has been registered.

Claims30

Dependent claims

A servo-hydraulic regulating system for controlling and actuating a load unit, the system comprising:

an operating line connecting a pressure fluid supply and the load unit;
a proportional valve incorporated into said operating line for controlling the load unit, said proportional valve being controlled by a measuring bridge which generates output pressure signals which control a position of said proportional valve, said proportional valve having a neutral setting in which said operating line is blocked, wherein said proportional valve assumes said neutral setting when said measuring bridge is balanced;
and
a safety circuit comprising a safety valve arrangement incorporated into said operating line, wherein said safety valve arrangement includes a directional control valve in said operating line, said directional control valve having a first valve position which opens said operating line, and a second valve position which blocks said operating line, wherein, in a power-up condition of the system, said safety valve arrangement blocks said operating line until said measuring bridge is balanced.

1 more element

A safety circuit in a servo-hydraulic regulating system for the hydraulic control and actuation of a load unit, the servo-hydraulic regulating system having an operating line communicating with a pressure fluid supply, a proportional valve for controlling the load unit and having a neutral setting which blocks the operating line, and a measuring bridge which generates output pressure signals for controlling setting of the proportional valve;

the safety circuit comprising:
a safety valve arrangement provided in the operating line, said safety circuit valve arrangement blocking the operating line when the measuring bridge is not balanced, said safety valve arrangement including a directional control valve incorporated into the operating line, said directional control valve including a directional control valve piston, wherein a first position of said directional control valve piston opens the operating line and a second position of said directional control valve piston closes the operating line, wherein, in a power-up of the servo-hydraulic regulating system, said directional control valve is adapted to close the operating line until the measuring bridge is balanced.

Dependencies are inferred from the claim text.

Safety circuit for a servo-hydraulic regulating system

Life of this patent

Safety circuit for a servo-hydraulic regulating system

Life of this patent

Abstract

Claims30