# US 9,518,571 B2 · Sealed compressor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,571 B2 - Document ID: US9518571B2 - Status: Granted - Kind: B2 - Application number: 13/460,141 - Filed: 2012-04-30 - Published: 2012-11-15 - Granted: 2016-12-13 - Earliest claimed: 2011-05-09 - Assignees: Panasonic Intellectual Property Management Co., Ltd. - Applicants: Masakazu Yamaoka; Yasushi Hayashi; Makoto Katayama - Inventors: Masakazu Yamaoka; Yasushi Hayashi; Makoto Katayama - Web page: https://patentgrep.com/patent/US9518571B2 ## CPC - F04B 35/04: the means being electric - F04B 39/0005: {adaptations of pistons} - F04B 39/1066: {Valve plates} - F04B 7/0216: {and having an oscillating movement} - 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 A sealed compressor comprises an electric element; a compression element; and a sealed container accommodating the electric element and the compression element; wherein the compression element includes a cylinder block defining a compression chamber; a piston which is reciprocatable inside the compression chamber; and a valve plate disposed to close an opening end of the compression chamber and having a discharge hole which provides communication between inside and outside of the compression chamber; the piston has a first groove on a tip end surface thereof which faces the valve plate, the first groove having a predetermined width and extending from an outer peripheral edge portion of the tip end surface toward a portion of the tip end surface which faces the discharge hole; and a tip end portion of the first groove is positioned in the portion of the tip end surface which faces the discharge hole and is inclined. ## Claims ### Claim 1 A sealed compressor comprising: an electric element; a compression element driven by the electric element; and a sealed container accommodating the electric element and the compression element; wherein the compression element includes a cylinder block defining a compression chamber; a piston which is reciprocatable inside the compression chamber; and a valve plate disposed to close an opening end of the compression chamber and having a discharge hole which provides communication between inside and outside of the compression chamber; the piston has a first groove on a tip end surface thereof which faces the valve plate, the first groove having a predetermined width and extending from an outer peripheral edge portion of the tip end surface toward a portion of the tip end surface which faces the discharge hole; the piston is provided with a projection having a top surface, on the tip end surface of the piston which faces the valve plate; the projection is positioned in the portion of the tip end surface which faces the discharge hole; the projection is inserted into the discharge hole of the valve plate in a state where the piston is at a top dead center, the projection has a flat surface facing a flow of a working fluid, an angle θ formed between the tip end surface of the piston and the flat surface of the projection protruding from the tip end surface is equal to or larger than 95 degrees and equal to or smaller than 110 degrees; and a ratio of an area of the top surface of the projection with respect to an area of a bottom surface of the projection, the bottom surface being connected to the tip end surface of the piston, is in a range of 0.2 to 0.75; a ratio of an area of the bottom surface of the projection with respect to an area of an opening of the discharge hole is set to a value in a range of 0.3 to 0.6; and a ratio of a height of the projection with respect to a thickness of the valve plate is set to a value in a range of 0.65 to 0.75. ### Claim 2 (depends on 1) The sealed compressor according to claim 1, wherein the tip end surface of the piston has a circular shape; and the predetermined width of the first groove is not less than 10% of a diameter of the piston and not greater than 30% of the diameter of the piston. ### Claim 3 (depends on 1) The sealed compressor according to claim 1, wherein the piston has a second groove on the tip end surface thereof which faces the valve plate, the second groove having a predetermined width and extending from the outer peripheral edge portion of the tip end surface toward the portion of the tip end surface which faces the discharge hole; and a base end portion of the second groove is most distant from a base end portion of the first groove; a tip end portion of the second groove is positioned in the portion of the tip end surface which faces the discharge hole and is inclined. ### Claim 4 (depends on 3) The sealed compressor according to claim 3, wherein the first groove and the second groove communicate with each other. ### Claim 5 (depends on 4) The sealed compressor according to claim 4, wherein the projection has a pair of side walls which are parallel to a direction in which the first groove extends. ### Claim 6 (depends on 1) The sealed compressor according to claim 1, wherein the projection has a center axis conforming to a center axis of the discharge hole. ### Claim 7 (depends on 1) The sealed compressor according to claim 1, wherein the first groove extends along a diameter of the piston which passes through the portion of the tip end surface which faces the discharge hole; and a base end portion of the first groove is positioned on a portion of the outer peripheral edge portion which is distant from the portion of the tip end surface which faces the discharge hole. ### Claim 8 (depends on 1) The sealed compressor according to claim 1, wherein the first groove has a shape in which an angle formed between an inclined surface forming a tip end portion and the tip end surface of the piston is not less than 90 degrees and not greater than 110 degrees. ### Claim 9 (depends on 8) The sealed compressor according to claim 8, wherein the projection protrudes from the tip end surface of the piston along the inclined surface forming the tip end portion of the first groove. ### Claim 10 (depends on 8) The sealed compressor according to claim 8, wherein the predetermined width of the first groove is not less than 2 mm and not greater than 6 mm, and a portion of the first groove which is other than the tip end portion has a depth which is not less than 20 μm and not greater than 60 μm. ### Claim 11 (depends on 1) The sealed compressor according to claim 1, wherein the first groove has a shape in which a bottom surface thereof is inclined to have a depth decreasing from a base end portion thereof toward a tip end portion. ### Claim 12 (depends on 11) The sealed container according to claim 11, wherein the first groove has a shape in which the base end portion has a depth which is not less than 10 μm and not greater than 500 μm. ### Claim 13 (depends on 1) The sealed compressor according to claim 1, wherein the ratio of the area of the top surface of the projection with respect to the area of the bottom surface of the projection is in a range of 0.5 to 0.75. ### Claim 14 (depends on 1) The sealed compressor according to claim 1, wherein the top surface of the projection is planar. ### Claim 15 (depends on 1) The sealed compressor according to claim 1, wherein the first groove has an inclined surface forming a tip end portion of the first groove; and the predetermined width of the first groove is not less than 2 mm and not greater than 6 mm, and a portion of the first groove which is other than the tip end portion has a depth which is not less than 20 μm and not greater than 60 μm.