# US 2019/0170168 A1 · Method for producing piston assembly and hydraulic fluid device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170168 A1 - Document ID: US20190170168A1 - Status: Published application - Kind: A1 - Application number: 16/324,297 - Filed: 2017-06-27 - Published: 2019-06-06 - Earliest claimed: 2016-08-10 - Assignees: SMC Corporation - Applicants: Smc Corporation - Inventors: Tsukasa ODAKA - Web page: https://patentgrep.com/patent/US20190170168A1 ## CPC - F15B 15/1452: {Piston sealings} - F15B 15/14: of the straight-cylinder type - F15B 15/1447: {Pistons; Piston to piston rod assemblies} - F15B 15/2861: {using magnetic means} - F16J 1/005: {obtained by assembling several pieces} - F16J 1/008: {with sealing lips} - F16J 9/12: Details - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - F16J: PISTONS {(specially adapted for dampers F16F9/32)}; CYLINDERS; SEALINGS ## Abstract A hydraulic fluid cylinder is equipped with a cylinder tube, a piston unit, and a piston rod. The piston unit has a piston body comprising a plurality of members and provided with a gasket-mounting groove. The piston body has a first piston member and a second piston member which are layered in the axial direction. The gasket-mounting groove is formed from a combination of at least two members. A thin section exhibiting depth in the axial direction is provided in the first piston member and/or the second piston member. ## Claims ### Claim 1 A fluid pressure device comprising: a body having a slide hole inside the body; a piston unit movable in an axial direction inside the slide hole; and a piston rod protruding from the piston unit in the axial direction; wherein: the piston unit includes a packing and a piston body comprising a plurality of members, the piston body being provided with a packing mounting groove in which the packing is mounted; the piston body includes, as the plurality of members, a first piston member and a second piston member stacked in the axial direction; a combination of at least two members of the plurality of members defines the packing mounting groove; and one or both of the first piston member and the second piston member are provided with a lightening portion having a depth in the axial direction. ### Claim 2 (depends on 1) The fluid pressure device according to claim 1, wherein the first piston member and the second piston member are castings. ### Claim 3 (depends on 1) The fluid pressure device according to claim 1, wherein the lightening portion has a through-hole passing through only one of the first piston member and the second piston member in the axial direction. ### Claim 4 (depends on 3) The fluid pressure device according to claim 3, wherein: one member of the first piston member and the second piston member that is provided with the through-hole includes a protruding portion protruding toward another member of the first piston member and the second piston member that is not provided with the through-hole; and the protruding portion has, on an outer circumferential pan thereof, a recess portion recessed inward and which constitutes part of the through-hole. ### Claim 5 (depends on 4) The fluid pressure device according to claim 4, wherein: the piston body further includes a magnet or a spacer as the plurality of members; and the protruding portion has a supporting protrusion protruding outward on the outer circumferential part and at a circumferential position different from a position of the recess portion, the supporting protrusion being configured to support the magnet or the spacer. ### Claim 6 (depends on 4) The fluid pressure device according to claim 4, wherein: the one member provided with the through-hole is provided with a wall portion protruding outwardly toward the through-hole; and the wall portion is disposed at a position adjoining the recess portion on a side remote, in the axial direction, from the other member not provided with the through-hole. ### Claim 7 (depends on 6) The fluid pressure device according to claim 6, wherein the recess portion is provided with a rib configured to reinforce the wall portion. ### Claim 8 (depends on 1) The fluid pressure device according to claim 1, wherein: the lightening portion includes a first lightening portion defined in the first piston member and a second lightening portion defined in the second piston member; one of the first lightening portion and the second lightening portion is a through-hole passing through the corresponding piston member in the axial direction; and another of the first lightening portion and the second lightening portion is a bottomed groove having a depth in the axial direction. ### Claim 9 (depends on 8) The fluid pressure device according to claim 8, wherein: the through-hole comprises a plurality of through-holes disposed at intervals in a circumferential direction; and the groove comprises a plurality of grooves disposed at intervals in the circumferential direction. ### Claim 10 (depends on 9) The fluid pressure device according to claim 9, wherein: one member of the first piston member and the second piston member that is provided with the plurality of through-holes includes a protruding portion protruding toward another member of the first piston member and the second piston member that is provided with the plurality of grooves; the protruding portion has a plurality of supporting protrusions arranged at intervals in the circumferential direction on an outer circumferential part of the protruding portion, the supporting protrusions protruding outward; and the other member of the first piston member and the second piston member that is provided with the plurality of grooves has an abutting surface disposed between two of the grooves that are circumferentially adjacent to each other, the abutting surface being configured to abut against an end surface of at least one of the plurality of supporting protrusions. ### Claim 11 (depends on 10) The fluid pressure device according to claim 10, wherein: the plurality of supporting protrusions include a first supporting protrusion abutting against the abutting surface and a second supporting protrusion disposed at a circumferential position different from a position of the abutting surface; and a circumferential width of the second supporting protrusion is smaller than a circumferential width of the first supporting protrusion. ### Claim 12 (depends on 10) The fluid pressure device according to claim 10, wherein: one of the first piston member and the second piston member is provided with a positioning protrusion protruding in the axial direction; another of the first piston member and the second piston member is provided with a positioning recess recessed in the axial direction; and the positioning protrusion is inserted into the positioning recess. ### Claim 13 (depends on 1) The fluid pressure device according to claim 1, wherein the lightening portion comprises a plurality of lightening portions disposed at intervals in a circumferential direction. ### Claim 14 (depends on 1) The fluid pressure device according to claim 1, wherein the fluid pressure device is configured as a fluid pressure cylinder, a valve device, a length-measurement cylinder, a sliding table, or a chuck device. ### Claim 15 A method for producing a piston assembly provided with a piston unit including a packing mounted in a packing mounting groove and a piston rod protruding from the piston unit, comprising the steps of: stacking a plurality of members including a first piston member and a second piston member by relatively moving the packing and the plurality of members in an axial direction in sequence, relative to the piston rod; and securing the first piston member and the second piston member to the piston rod; wherein: the plurality of members constitute a piston body provided with the packing mounting groove; a combination of at least two members of the plurality of members defines the packing mounting groove; and one or both of the first piston member and the second piston member are provided with a lightening portion having a depth in the axial direction. ### Claim 16 (depends on 15) The method for producing the piston assembly according to claim 15, wherein the piston rod is in an upright position during the step of stacking the plurality of members.