# US 10,767,778 B2 · Servo valve > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,767,778 B2 - Document ID: US10767778B2 - Status: Granted - Kind: B2 - Application number: 16/224,837 - Filed: 2018-12-19 - Published: 2019-06-27 - Granted: 2020-09-08 - Earliest claimed: 2017-12-22 - Assignees: Hamilton Sunstrand Corporation - Applicants: Hamilton Sundstrand Corporation - Inventors: Zbigniew Jaśkiewicz - Web page: https://patentgrep.com/patent/US10767778B2 ## CPC - F16K 31/006: {having a free end} - F15B 13/043: with electrically-controlled pilot valves - F15B 13/0435: {the pilot valves being sliding valves} - F15B 13/0438: {the pilot valves being of the nozzle-flapper type} - F16K 31/007: {Piezoelectric stacks} - F16K 31/426: {the actuated valves being cylindrical sliding valves} - H10N 30/204: {using bending displacement, e.g. unimorph, bimorph or multimorph cantilever or membrane benders} - 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)} - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR ## Abstract A servo valve comprising first and second nozzles and first and second piezoelectric actuators arranged to control fluid flow through the first and second nozzles respectively. A first fluid flow path is defined between the first nozzle and the first piezoelectric actuator and a second fluid flow path is defined between the second nozzle and the second piezoelectric actuator. The first and second piezoelectric actuators are arranged such that applying a voltage to the first and second piezoelectric actuators causes a change in dimension thereof, which acts to open or restrict said first and second fluid flow paths respectively. ## Claims ### Claim 1 A servo valve comprising: first and second nozzles; and first and second piezoelectric actuators arranged to control fluid flow through the first and second nozzles respectively, wherein: a first fluid flow path is defined between the first nozzle and the first piezoelectric actuator; a second fluid flow path is defined between the second nozzle and the second piezoelectric actuator; and the first and second piezoelectric actuators are arranged such that applying a voltage to the first and second piezoelectric actuators causes a change in dimension thereof, which acts to open or restrict said first and second fluid flow paths respectively; and the servo valve further comprising: a servo valve housing including a pair of nozzle cavities, each housing a respective nozzle and piezoelectric actuator, wherein the piezoelectric actuators are retained in the nozzle cavities by contact between a first axial end of each piezoelectric actuator opposite a second axial end facing the nozzle and a wall defined by the respective nozzle cavity, wherein the wall is a common wall shared by the first and second nozzle cavities and separating the first and second nozzle cavities. ### Claim 2 (depends on 1) The servo valve of claim 1, wherein the first and second piezoelectric actuators are arranged such that the change in dimension thereof increases or decreases a gap between the first and second piezoelectric actuators and the first and second nozzles respectively. ### Claim 3 (depends on 1) The servo valve of claim 1, wherein the first and second nozzles define first and second nozzle axes, the first and second piezoelectric actuators extend along the first and second nozzle axes respectively, and the change in dimension of the first and second piezoelectric actuators causes the first and second piezoelectric actuators to expand or contract along the first and second nozzle axes respectively. ### Claim 4 (depends on 3) The servo valve of claim 3, wherein the first and second nozzle axes are aligned with each other. ### Claim 5 (depends on 1) The servo valve of claim 1, wherein each piezoelectric actuator comprises a piezoelectric element and a blocking element, the blocking element is at the second axial end of the piezoelectric actuator facing the respective nozzle, and comprises a surface for engaging a nozzle outlet opening in the respective nozzle. ### Claim 6 (depends on 1) The servo valve of claim 1, further comprising a first pair of caps each configured to hermetically seal a respective one of the pair of nozzle cavities from the exterior of the servo valve housing, wherein the caps are removably secured to the servo valve housing. ### Claim 7 (depends on 1) The servo valve of claim 1, wherein the servo valve housing further includes a spool cavity housing a spool, wherein the spool has a central spool axis, a first axial end and an opposing second axial end, and the spool is configured to translate axially along the spool axis in response to a fluid bias being placed on the spool between the first and second axial ends of the spool, and the servo valve further comprises a pair of opposing spool biasing members in contact with the first and second axial ends of the spool respectively, wherein the biasing members are configured to oppose axial translation of the spool along the central spool axis. ### Claim 8 (depends on 7) The servo valve of claim 7, further comprising: a supply port upstream of the first and second nozzle cavities in fluid communication with the first and second fluid flow paths via the first and second axial ends of the spool and respective first and second inlet orifices; a return port downstream of the nozzle cavities in fluid communication with the first and second fluid flow paths and the spool; and first and second control ports for providing fluid communication between the spool and a hydraulic actuator. ### Claim 9 (depends on 8) An actuation system comprising: the servo valve of claim 8; and a hydraulic actuator in fluid communication with the first and second control ports. ### Claim 10 (depends on 1) The servo valve of claim 1, wherein the servo valve is configured such that each piezoelectric actuator is independently controllable. ### Claim 11 A method of controlling a servo valve having first and second nozzles and first and second piezoelectric actuators, wherein a first fluid flow path is defined between the first nozzle and the first piezoelectric actuator and a second fluid flow path is defined between the second nozzle and the second piezoelectric actuator, the method comprising supplying a voltage to first and second piezoelectric actuators causing a change in dimension thereof which opens or restricts the first and second fluid flow paths defined between the first and second nozzles and first and second piezoelectric actuators respectively; and the servo valve also having: a servo valve housing including a pair of nozzle cavities, each housing a respective nozzle and piezoelectric actuator, wherein the piezoelectric actuators are retained in the nozzle cavities by contact between a first axial end of each piezoelectric actuator opposite a second axial end facing the nozzle and a wall defined by the respective nozzle cavity, wherein the wall is a common wall shared by the first and second nozzle cavities and separating the first and second nozzle cavities. ### Claim 12 (depends on 11) The method of claim 11, further comprising supplying voltage to each piezoelectric actuator independently to change the axial dimension of each piezoelectric actuator independently. ### Claim 13 (depends on 12) The method of claim 12, wherein the servo valve has a spool having a central spool axis, a first axial end and an opposing second axial end, the first nozzle is in fluid communication with the first axial end of the spool, and the second nozzle is in fluid communication with the second axial end of the spool, the method further comprising generating a fluid bias between the first and second axial ends of the spool by the opening or restricting of said first and second fluid flow paths by the first and second piezoelectric actuators respectively.