# US 2018/0024577 A1 · Pressure-limiting valve > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0024577 A1 - Document ID: US20180024577A1 - Status: Published application - Kind: A1 - Application number: 15/547,560 - Filed: 2016-01-09 - Published: 2018-01-25 - Earliest claimed: 2015-02-11 - Assignees: Hydac Fluidtechnik GmbH - Applicants: Hydac Fluidtechnik GmbH - Inventors: Peter BRUCK; Martin GRILL - Web page: https://patentgrep.com/patent/US20180024577A1 ## CPC - G05D 16/106: {Sleeve-like sensing elements; Sensing elements surrounded by the flow path} - F15B 13/024: {Pressure relief valves} - F16K 1/42: Valve seats (for double-seat valves F16K1/44) - F16K 15/026: {the valve member being a movable body around which the medium flows when the valve is open} - F16K 17/0433: {with vibration preventing means} - F16K 31/1221: {one side of the piston being spring-loaded} - F16K 31/408: {the discharge being effected through the piston and being blockable by an electrically-actuated member making contact with the piston} - F15B 13/0405: {for seat valves, i.e. poppet valves} - F15B 20/007: {Overload} - F15B 21/047: Preventing foaming, churning or cavitation - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - F16K: VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING {(devices for emptying and evacuating the excess liquid in valves or conduits F16L55/07)} ## Abstract A pressure-limiting valve with feed function, comprising a valve housing (20) having at least two connection points, in particular in the form of a working connection (A) and a tank connection (T), and having a spring-loaded pressure-limiting valve piston (22) which is mounted such as to be longitudinally movable in the valve housing (20), and having a spring-loaded non-return valve piston (56) for the implementation of the feed function, is characterized in that the non-return valve piston (56) is designed as a hollow piston and is mounted such as to be longitudinally movable in the valve housing (20). ## Claims ### Claim 1 A pressure-limiting valve with feed function, comprising a valve housing (20) having at least two connection points, in particular in the form of a work port (A) and a tank port (T), and having a spring-loaded pressure-limiting valve piston (22), which is guided in a longitudinally displaceable manner in the valve housing (20), and having a spring-loaded check-valve piston (56) for implementing the feed function, is characterized in that the check-valve piston (56) is designed as a hollow piston and is guided in a longitudinally displaceable manner in the valve housing (20). ### Claim 2 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that the two pistons (22, 56) are in contact with one another in the region of their free, mutually adjacent end faces to block the fluid-conducting connection between the two connection points (A, T), and in order to enable this connection, at least one piston (22, 56) moves away from the other piston (56, 22) in the axial direction. ### Claim 3 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that the two pistons (22, 56) are each provided with at least one travel stop (52, 54; 76, 78) within the valve housing (20), and in that the respective resetting springs (24, 58) for the assignable piston (22, 56) are guided in opposing mounting or spring spaces (46, 66) in the valve housing (20). ### Claim 4 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that for a seat-tight connection of the pistons (22, 56) with each other, the check-valve piston (56) is provided with an inclined surface (68), which engages in a cylindrical receiving space (70) on the end face of the pressure-limiting valve piston (22). ### Claim 5 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that the pressure-limiting valve piston (22) is provided with a pilot control orifice (50), which establishes a permanent fluid-conducting connection between the front and rear of this piston (22). ### Claim 6 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that the pressure-limiting valve piston (22) interacts with a valve pilot control (12) with a damping orifice (30), enabling a fluid-conducting connection from the pilot control orifice (50) to the tank port (T) if open. ### Claim 7 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that the tank port (T) is inserted radially and the work port (A) is inserted axially into the valve housing (20). ### Claim 8 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that the two pistons (22, 56) are in contact with one another in their fluid-blocking regulating position approximately in the region of the respective bore axis for the tank port (T). ### Claim 9 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that for implementing the feed function, the check-valve piston (56) moves in the direction of the work port (A) and the pressure-limiting valve piston (22) follows this movement until one of its travel stops (52) is reached and subsequently the check-valve piston (56) enables the connection between the two connection points (A, T) in a regulating manner. ### Claim 10 (depends on 1) The pressure-limiting valve according to claim 1, characterized in that for implementing the pressure-limiting function, a valve pilot control (12) having the pilot control orifice (SO) and the damping orifice (30) opens, and the pressure-limiting valve piston (22) moves away from the work port (A) and the check valve piston (56) follows this movement until one of its travel stops (76) is reached and subsequently the pressure-limiting valve piston (22) enables the connection between the two connection points (A, T) in a regulating manner.