# US 11,440,366 B1 · Frequency dependent pressure and/or flow fluctuation mitigation in hydraulic systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,440,366 B1 - Document ID: US11440366B1 - Status: Granted - Kind: B1 - Application number: 16/590,996 - Filed: 2019-10-02 - Granted: 2022-09-13 - Earliest claimed: 2018-10-03 - Assignees: ClearMotion, Inc. - Applicants: ClearMotion, Inc. - Inventors: Colin Patrick O'Shea; Joseph Thomas Belter; Brian Alexander Selden - Web page: https://patentgrep.com/patent/US11440366B1 ## CPC - B60G 17/016: characterised by their responsiveness, when the vehicle is travelling, to specific motion, a specific condition, or driver input {(B60G17/017 takes precedence)} - B60G 13/08: hydraulic - B60G 17/08: Characteristics of fluid dampers (adjusting fluid dampers in general F16F9/44 - F16F9/53) - F16F 9/065: {Expansion chamber provided on the upper or lower end of a damper, separately there from or laterally on the damper} - F16F 9/46: allowing control from a distance {, i.e. location of means for control input being remote from site of valves, e.g. on damper external wall (attachment of valve units to cylinders F16F9/325)} - F16F 9/512: Means responsive to load action, {i.e. static load} on the damper or {dynamic} fluid pressure {changes} in the damper, {e.g. due to changes in velocity (F16F9/504, F16F9/516 take precedence; non-automatic damper adjustment from a distance using servo control, the servo pressure being created by the flow of damping fluid F16F9/465; self-pumping fluid springs in vehicle suspensions B60G17/044)} - B60G 2202/24: Fluid damper - B60G 2202/413: Hydraulic actuator - B60G 2202/416: using a pump, e.g. in the line connecting the lower chamber to the upper chamber of the actuator - B60G 2202/42: Electric actuator - B60G 2400/10: Acceleration; Deceleration - B60G: VEHICLE SUSPENSION ARRANGEMENTS (air-cushion vehicles B60V; {cycle suspensions B62K25/00}) - F16F: SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION ## Abstract Active suspension systems including actuators with combinations of accumulators and flow restrictions, as well as their methods of operation, are described. In some embodiments, methods and constructions for mitigating pump ripple and/or resonances between different hydraulic components are also described. ## Claims ### Claim 1 An actuator comprising: a housing including a first volume and a second volume with a piston slidably disposed between the first volume and the second volume; a hydraulic device fluidly coupled to the first volume and the second volume along a first flow path extending between the first volume and the second volume, wherein in a first operating mode the hydraulic device operates in a first direction and in a second operating mode the hydraulic device operates in a second direction; an electric motor/generator operatively coupled to the hydraulic device; a first accumulator disposed along the first flow path between the hydraulic device and the first volume; a second accumulator disposed along the first flow path between the hydraulic device and the second volume; and at least one flow restriction located along the first flow path, wherein the at least one flow restriction is configured to damp a flow in the first flow path between the first accumulator and the second accumulator. ### Claim 2 (depends on 1) The actuator of claim 1, wherein the at least one flow restriction is positioned between the first accumulator and the first volume or the second accumulator and the second volume. ### Claim 3 (depends on 1) The actuator of claim 1, wherein the at least one flow restriction includes a first flow restriction located between the first accumulator and the first volume and a second flow restriction located between the second accumulator and the second volume. ### Claim 4 (depends on 1) The actuator of claim 1, wherein the housing comprises a twin tube housing including an inner tube and a concentrically located outer tube wherein the at least one flow restriction is formed by an annular gap between the inner tube and the concentrically located outer tube. ### Claim 5 (depends on 1) The actuator of claim 1, wherein the at least one flow restriction is constructed and arranged to damp frequencies between or equal to 75 Hz and 150 Hz. ### Claim 6 (depends on 1) The actuator of claim 1, wherein the first accumulator is a first flow through accumulator. ### Claim 7 (depends on 1) The actuator of claim 1, wherein the second accumulator is a flow through accumulator. ### Claim 8 (depends on 1) The actuator of claim 1, wherein the second accumulator is a single port accumulator. ### Claim 9 (depends on 8) The actuator of claim 8, wherein an inlet to the single port accumulator is constructed and arranged to function as a low pass filter. ### Claim 10 (depends on 9) The actuator of claim 9, wherein the inlet to the single port accumulator comprises a shimstack. ### Claim 11 A vehicle comprising: an active suspension system including one or more actuators, wherein each actuator comprises: a housing including a first volume and a second volume with a piston slidably disposed between the first volume and the second volume; a hydraulic device fluidly coupled to the first volume and the second volume along a first flow path extending between the first volume in the second volume, wherein in a first operating mode the hydraulic device operates in a first direction and in a second operating mode the hydraulic device operates in a second direction; an electric motor/generator operatively coupled to the hydraulic device; a second flow path extending between the first volume and the second volume that bypasses the hydraulic device; and a valve that selectively permits flow through the second flow path based at least partly on the vehicle's speed, wherein the valve permits flow through the second flow path when the vehicle velocity is less than a threshold velocity and prevents flow through the second flow path when the vehicle velocity is greater than the threshold velocity. ### Claim 12 (depends on 11) The vehicle of claim 11, wherein the threshold velocity is between 20 miles per hour and 30 miles per hour. ### Claim 13 (depends on 11) The vehicle of claim 11, further comprising at least one flow restriction disposed along the second flow path. ### Claim 14 (depends on 13) The vehicle of claim 13, further comprising a first accumulator disposed along the first flow path between the hydraulic device and the first volume and a second accumulator disposed along the first flow path between the hydraulic device and the second volume. ### Claim 15 (depends on 14) The vehicle of claim 14, wherein the at least one flow restriction is constructed to damp a flow between the first accumulator and the second accumulator.