# US 2014/0150641 A1 · Axial piston machine having a conical piston > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0150641 A1 - Document ID: US20140150641A1 - Status: Published application - Kind: A1 - Application number: 14/095,295 - Filed: 2013-12-03 - Published: 2014-06-05 - Earliest claimed: 2012-12-04 - Assignees: Robert Bosch GmbH - Applicants: Robert Bosch GmbH - Inventors: Michael Ruckgaber; Rolf Brockerhoff - Web page: https://patentgrep.com/patent/US20140150641A1 ## CPC - F01B 3/0076: {Connection between cylinder barrel and inclined swash plate} - F04B 1/124: Pistons - F04B 1/24: inclined to the main shaft axis - F01B: MACHINES OR ENGINES, IN GENERAL OR OF POSITIVE-DISPLACEMENT TYPE, e.g. STEAM ENGINES (of rotary-piston or oscillating-piston type F01C; of non-positive-displacement type F01D; internal-combustion engines F02B; combustion-product engine plants F02G; machines or engines, other than of positive-displacement type, for liquids F03B; positive-displacement engines driven by liquids F03C; wind motors F03D; positive-displacement machines for liquids F04B; rotary-piston, or oscillating-piston, positive-displacement machines for liquids F04C) - 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 An axial piston machine includes a housing, a drive shaft, and a cylinder drum. The drive shaft is mounted in the housing so as to be rotatable with respect to a first axis of rotation. The cylinder drum is mounted so as to be rotatable with respect to a second axis of rotation. The cylinder drum has at least one cylinder bore that linearly guides an elongate piston. The piston has a first end connected to the drive shaft by a ball joint and a section in the form of a circular cone which tapers toward the first end. The piston also has a spherical section at the second end that is situated opposite the first end. The cone-shaped section merges without offsets and kinks into the spherical section. The piston has a flat end face at the second end which defines a plane that intersects the spherical section. ## Claims ### Claim 1 An axial piston machine, comprising: a housing; a drive shaft mounted in the housing in such a way so as to be rotatable with respect to a first axis of rotation; a cylinder drum mounted so as to be rotatable with respect to a second axis of rotation, the cylinder drum defining at least one circular-cylindrical cylinder bore; and an elongate piston accommodated in the at least one circular-cylindrical cylinder bore in a manner which allows linear motion, the piston having (i) a first end connected to the drive shaft by a ball joint, (ii) a section in the form of a circular cone which tapers toward the first end, and (iii) a spherical section at a second end situated opposite the first end, wherein the cone defined by the section in the form of a circular cone merges without offsets and kinks into the spherical section, and wherein the piston has a flat end face at the second end which forms a corner with the spherical section. ### Claim 2 (depends on 1) The axial piston machine according to claim 1, wherein the corner between the end face and the spherical section of the piston has a radius or a chamfer. ### Claim 3 (depends on 1) The axial piston machine according to claim 1, wherein the cylinder drum is composed of cast iron. ### Claim 4 (depends on 3) The axial piston machine according to claim 3, wherein the cylinder drum is produced by casting. ### Claim 5 (depends on 3) The axial piston machine according to claim 3, wherein the cylinder bore has a surface layer that has a greater hardness than the remainder of the cylinder drum. ### Claim 6 (depends on 1) The axial piston machine according to claim 1, wherein the section of the piston in the form of a circular cone is interrupted adjacent to the spherical section by an encircling first groove, and wherein a separate first sealing ring is accommodated in the first groove. ### Claim 7 (depends on 6) The axial piston machine according to claim 6, wherein the section of the piston in the form of a circular cone is interrupted by an encircling second groove, wherein a separate second sealing ring is accommodated in the second groove, and wherein the second sealing ring is arranged on the side of the first sealing ring remote from the spherical section. ### Claim 8 (depends on 1) The axial piston machine according to claim 1, wherein a width of the spherical section is between 2 mm and 8 mm. ### Claim 9 (depends on 1) The axial piston machine according to claim 1, wherein a spherical head of the ball joint is arranged on the first end of the piston, and wherein a distance between the center of the spherical head and the spherical section of the piston is between 80 mm and 140 mm. ### Claim 10 (depends on 1) The axial piston machine according to claim 1, wherein the axial piston machine is configured as a pump or a motor.