# US 9,435,359 B2 · Adaptive hydraulic cylinder with floating seal interface > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,435,359 B2 - Document ID: US9435359B2 - Status: Granted - Kind: B2 - Application number: 13/371,504 - Filed: 2012-02-13 - Published: 2013-08-15 - Granted: 2016-09-06 - Earliest claimed: 2012-02-13 - Assignees: Schlumberger Technology Corporation - Applicants: Kenneth J Stoddard; Jared M Mangum - Inventors: Kenneth J Stoddard; Jared M Mangum - Web page: https://patentgrep.com/patent/US9435359B2 ## CPC - F15B 15/1466: {Hollow piston sliding over a stationary rod inside the cylinder} - B60T 17/081: {Single service brake actuators} - F04B 39/0022: {piston rods} - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - B60T: VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL (electrodynamic brake systems for vehicle, in general B60L; brakes per se, i.e. devices where braking effect occurs, including ultimate brake actuators, F16D); ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) ## Abstract In one possible implementation, a misalignment-tolerant hydraulic actuator, e.g., for a submersible hydraulic diaphragm insert pump (HDI), has a floating piston that can reciprocate while decoupled from collinearity with a cylinder barrel and a central feed rod that slides through a central axis of the piston. The floating seal can be integrated or provided by a separate insert and provides a pivotable interface between the piston and center rod, allowing these components freedom of motion to avoid elastic deformation, friction, power loss, and early wear when misalignment or transverse forces on an external end of the piston rod are present. Bearing placement can also be selected to eliminate over-constraint. ## Claims ### Claim 1 A hydraulic cylinder, comprising: a barrel; a piston slidably disposed within the barrel, the piston also being slidably disposed on a center rod within the barrel; a piston rod coupled to the piston, the piston rod having a hollow interior extending axially therethrough, the center rod having a rod stop through which fluid is delivered to the hollow interior of the piston rod, wherein the rod stop does not radially contact an interior surface of the piston rod; a first seal interface between the piston and the center rod to decouple a displacement axis of the piston from a longitudinal axis of the center rod; and a second seal interface between the piston and the barrel to decouple the piston from the barrel. ### Claim 2 (depends on 1) The hydraulic cylinder of claim 1, wherein the first seal interface enables the piston to move in rotational and translational degrees of freedom with respect to the center rod. ### Claim 3 (depends on 1) The hydraulic cylinder of claim 1, wherein the first seal interface comprises one of a separate floating insert member or a seal interface integrated with the piston. ### Claim 4 (depends on 1) The hydraulic cylinder of claim 1, wherein the first seal interface makes a self-lining bearing with the center rod; and the first seal interface also makes a hydraulic seal with the piston. ### Claim 5 (depends on 4) The hydraulic cylinder of claim 4, further comprising a gland in the seal interface placed to hold a seal at a pivot point to provide a freedom of movement of a longitudinal axis of the piston with respect to a longitudinal axis of the first seal interface. ### Claim 6 (depends on 1) The hydraulic cylinder of claim 1, further comprising a single ring of bearing support around the piston to allow a freedom of movement of a longitudinal axis of the piston with respect to the displacement axis of the piston in the cylinder. ### Claim 7 (depends on 1) The hydraulic cylinder of claim 1, further comprising: a piston rod support or cylinder endcap; a hole in the piston rod support or cylinder endcap for the piston rod; a bearing in the piston rod support or cylinder endcap to contact the piston rod in substantially a single ring of contact to provide a freedom of movement for a longitudinal axis of the piston rod with respect to a displacement axis of the piston in the cylinder. ### Claim 8 (depends on 7) The hydraulic cylinder of claim 7, wherein when the hydraulic cylinder operates, the cylinder, the piston, the piston rod, and the center rod are free to self-align on slightly differently near axes while remaining fully constrained without over-constraint, while maintaining a hydraulic seal between the components of the hydraulic cylinder. ### Claim 9 A misalignment-tolerant hydraulic actuator for a submersible pump, comprising: a cylinder barrel; a piston in the cylinder barrel to provide a reciprocating stroke; a piston rod connected to the piston to transfer the reciprocating stroke from the hydraulic actuator to the submersible pump, the piston rod having an axial passage extending through the piston rod to deliver actuating fluid; a center rod disposed in a bore through a central axis of the piston, the center rod having a rod stop through which the actuating fluid is delivered to the axial passage of the piston rod, wherein the rod stop does not radially contact an interior surface of the piston rod; a first interface between the center rod and the piston to decouple a displacement axis of the piston in the cylinder barrel from a longitudinal axis of the center rod; and a second interface between the piston and the cylinder barrel to decouple the piston from the cylinder barrel. ### Claim 10 (depends on 9) The misalignment-tolerant hydraulic actuator of claim 9, wherein the first interface allows the piston and the center rod to slide in relation to each other along slightly differently linear axes without over-constraint while maintaining a hydraulic seal between the piston and the center rod. ### Claim 11 (depends on 9) The misalignment-tolerant hydraulic actuator of claim 9, further comprising: the first interface comprising a first pivotable bearing; the second interface comprising a second pivotable bearing; and wherein when the misalignment-tolerant hydraulic actuator operates, the cylinder barrel, the piston, and the center rod are free to self-align on slightly differently linear axes without over-constraint while maintaining a hydraulic seal between the components of the misalignment-tolerant hydraulic actuator. ### Claim 12 (depends on 11) The misalignment-tolerant hydraulic actuator of claim 11, further comprising: a stop on the center rod to move within a hollow bore of the piston rod; and wherein when the misalignment-tolerant hydraulic actuator operates, the cylinder barrel, the piston with piston rod, and the center rod are free to self-align on slightly different linear axes without over-constraint while maintaining a hydraulic seal between the components of the misalignment-tolerant hydraulic actuator. ### Claim 13 (depends on 9) The misalignment-tolerant hydraulic actuator of claim 9, wherein the first interface decouples a linear axis of reciprocation of the piston from a longitudinal axis of the center rod without introducing a constraint between the piston and the center rod. ### Claim 14 (depends on 9) The misalignment-tolerant hydraulic actuator of claim 9, wherein the first interface enables the piston to freely move and self-position in rotational and translational degrees of freedom with respect to the center rod.