# US 2025/0092956 A1 · Valve > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0092956 A1 - Document ID: US20250092956A1 - Status: Published application - Kind: A1 - Application number: 18/820,967 - Filed: 2024-08-30 - Published: 2025-03-20 - Earliest claimed: 2023-09-19 - Assignees: Microtecnica S.r.I. - Applicants: Microtecnica S.r.I. - Inventors: Dario Molinelli - Web page: https://patentgrep.com/patent/US20250092956A1 ## CPC - F16K 17/04: spring-loaded - F16K 17/0433: {with vibration preventing means} - B01D 35/1475: {Pressure relief valves or pressure control valves} - F16K 1/50: Preventing rotation of valve members - F16K 27/0209: {Check valves or pivoted valves} - F16K 47/0111: {the valve members comprising a plunger sliding within a fixed dashpot} - B01D 2201/167: Single-way valves - F16K 2200/501: Cartridge valves - 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)} - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) ## Abstract An assembly for a pressure relief valve includes a valve seat member, a piston and a fluid outlet. The valve seat member includes a fluid inlet, a seat sealing surface and an axial bore. The axial bore includes a first cavity and a second cavity. The seat sealing surface is disposed axially between the first cavity and the second cavity and the fluid inlet is disposed axially between the seat sealing surface and the second cavity. The piston is movable within the axial bore. The piston includes a piston sealing surface, a first cylindrical portion and a second cylindrical portion. The first cylindrical portion configured to be retained by and slidably engage with the first cavity and the second cylindrical portion configured to be retained by and slidably engage with the second cavity. The piston sealing surface is disposed axially between the first cylindrical portion and the second cylindrical portion. ## Claims ### Claim 1 An assembly for a pressure relief valve, comprising: a valve seat member including: a fluid inlet; a seat sealing surface; and an axial bore, the axial bore including a first cavity and a second cavity, wherein the seat sealing surface is disposed axially between the first cavity and the second cavity and the fluid inlet is disposed axially between the seat sealing surface and the second cavity; a fluid outlet; and a piston movable within the axial bore, the piston including: a piston sealing surface; a first cylindrical portion; and a second cylindrical portion, the first cylindrical portion configured to be retained by and slidably engage with the first cavity and the second cylindrical portion configured to be retained by and slidably engage with the second cavity, wherein the piston sealing surface is disposed axially between the first cylindrical portion and the second cylindrical portion; wherein the piston has a first position in which the piston sealing surface is engaged with the seat sealing surface such that a fluid path between the fluid inlet and the fluid outlet is closed, and a second position in which the fluid path between the fluid inlet and the fluid outlet is open; and wherein the first cylindrical portion has a first radius, the second cylindrical portion has a second radius and the second radius is less than the first radius. ### Claim 2 (depends on 1) The assembly according to claim 1, wherein the piston comprises a piston bore that passes axially through the first cylindrical portion and the fluid outlet is formed by the piston bore. ### Claim 3 (depends on 1) The assembly according to claim 1, wherein the fluid outlet is formed by one or more grooves in a radially outer surface of the first cylindrical portion. ### Claim 4 (depends on 1) The assembly according to claim 1, wherein a first radial clearance between the first cavity and the first cylindrical portion is less than 25 micrometres. ### Claim 5 (depends on 4) The assembly according to claim 4, wherein the first radial clearance is between 15 and 25 micrometres. ### Claim 6 (depends on 1) The assembly according to claim 1, wherein the axial bore includes a dampening cavity having a damping volume, wherein the second cylindrical portion is disposed between the fluid inlet and the dampening cavity, and wherein a second radial clearance between the second cavity and the second cylindrical portion is configured to restrict flow of fluid into and out of the damping volume. ### Claim 7 (depends on 6) The assembly according to claim 6, wherein the second radial clearance is less than 35 micrometres, wherein, optionally, the second radial clearance is between 25 and 35 micrometres. ### Claim 8 (depends on 6) The assembly according to claim 6, wherein the damping volume is configured to dampen oscillations of the piston. ### Claim 9 (depends on 1) The assembly according to claim 1, wherein the piston includes a third cylindrical portion disposed axially between the first cylindrical portion and the second cylindrical portion, the third cylindrical portion having a third radius and comprising the piston sealing surface, the third radius being larger than second radius and less than first radius. ### Claim 10 (depends on 9) The assembly according to claim 9, wherein the axial bore includes a third cavity surrounding the third cylindrical portion, the third cavity comprising a compensating volume surrounding the third cylindrical portion. ### Claim 11 (depends on 1) The assembly according to claim 1, wherein the valve seat member and the piston are formed from stainless steel, wherein, optionally, the stainless steel comprises 440-series stainless steel, such as 440C stainless steel. ### Claim 12 (depends on 1) A valve comprising: a body; an inlet; an outlet; an assembly as recited in claim 1, wherein the fluid inlet is in communication with the inlet of the valve and the fluid outlet is in communication with the outlet of the valve; and a resilient member configured to bias the piston against the valve seat member. ### Claim 13 (depends on 12) The valve according to claim 12, wherein the body is integral with the valve seat member. ### Claim 14 (depends on 12) The valve according to claim 12, further comprising: a spring guide that comprises a conical, frustoconical or spherical surface configured to engage with a guide surface of the piston. ### Claim 15 (depends on 14) The valve according to claim 14, wherein, the guide surface is conical or frustoconical. ### Claim 16 (depends on 12) A filtration system for filtering hydraulic fluid comprising: a pressurised fluid source; a fluid reservoir; a controllable valve arranged to selectively communicate the pressurised fluid source with a fluid supply line and the fluid reservoir; and a valve according to claim 12; wherein the valve is arranged to communicate the pressurised fluid source with fluid reservoir when a differential pressure between the pressurised fluid source and the fluid reservoir exceeds a predetermined pressure threshold.