# US 7,607,384 B2 · Piston for an axial-piston engine of the inclined-axis type and process for manufacturing such pistons > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,384 B2 - Document ID: US7607384B2 - Status: Granted - Kind: B2 - Application number: 11/664,010 - Filed: 2005-12-14 - Published: 2008-04-10 - Granted: 2009-10-27 - Earliest claimed: 2004-12-22 - Assignees: Brueninghaus Hydromatik GmbH - Inventors: Rolf Brockerhoff - Web page: https://patentgrep.com/patent/US7607384B2 ## CPC - B23P 15/10: pistons - F04B 1/124: Pistons - Y10T 29/49249: Piston making - B23P: METAL-WORKING NOT OTHERWISE PROVIDED FOR; COMBINED OPERATIONS; UNIVERSAL MACHINE TOOLS (arrangements for copying or controlling B23Q) - 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) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A piston (2) for a piston engine, in particular for an axial-piston engine (1) of the inclined-axis type, comprises a conical section (26), a neck region (19) and a ball end (9) which is formed onto said neck region (19), a clearance (15) which is constructed in the piston and a pin (14) which is constructed in said clearance (15). The wall (20) of the piston (2) has different thicknesses of material in different sections of its axial length. ## Claims ### Claim 1 Piston for an axial-piston engine of the inclined-axis type, said piston comprising a conical section, a neck region and a ball end which is formed onto said neck region, a clearance which is constructed in the piston, and a pin which is constructed in said clearance, wherein the wall of the piston has different thicknesses of material in different sections of its axial length, wherein a radial diameter of the clearance decreases towards the base of the piston; wherein the clearance is closed off, in the neck region, by the abutment of an inner face of the wall of said clearance against the pin; wherein at least one bore is constructed in the neck region; and wherein the clearance is fillable with a hydraulic fluid though the at least one bore. ### Claim 2 (depends on 1) Piston according to claim 1, wherein the thickness of the material of the piston in the base of said piston and in the region of the ball end is greater than in the conical section. ### Claim 3 (depends on 1) Piston according to claim 1, wherein a longitudinal bore is constructed in the pin. ### Claim 4 (depends on 3) Piston according to claim 3, wherein a restrictor is provided in the longitudinal bore. ### Claim 5 (depends on 1) Piston according to claim 1, wherein the piston is equipped with piston rings. ### Claim 6 (depends on 5) Piston according to claim 5, wherein the piston rings are disposed in grooves in the region of the base of the piston. ### Claim 7 (depends on 1) Piston according to claim 1, wherein a cavity is constructed in the ball end. ### Claim 8 (depends on 1) Piston according to claim 1, wherein the piston is manufactured from round stock by cold extrusion and rotary swaging. ### Claim 9 (depends on 8) Piston according to claim 8, wherein the thickness of the material of the round stock is so dimensioned that it amounts to 1.1 to 1.5 times the diameter of the ball end. ### Claim 10 (depends on 9) Piston according to claim 9, wherein the diameter of the round stock determines the maximum diameter of the piston. ### Claim 11 (depends on 8) Piston according to claim 8, wherein the thickness of the material of the round stock is so dimensioned that it amounts to 1.15 to 1.2 times the diameter of the ball end. ### Claim 12 (depends on 1) Piston according to claim 1, wherein said conical section, neck region, ball end and pin are constituted of a unitary structure. ### Claim 13 Process for manufacturing a piston for an axial-piston engine of the inclined-axis type, wherein said piston comprises a conical section, a neck region and a ball end which is formed onto said neck region, a clearance which is constructed in the piston and a pin which is constructed in said clearance, and wherein the wall of the piston has a different thicknesses of material in different sections of its axial length, wherein said process comprises the following steps: a) the trimming of round stock to the desired length; b) the manufacture of an internal contour by cold extrusion; c) the preparation of the external contour by rough-turning; d) the manufacture of the external contour by round swaging; and c) finishing. ### Claim 14 (depends on 13) Process according to claim 13, wherein the second process step b) comprises the following partial steps: the selection of a suitable diameter for the pin and the clearance; the selection of the thickness of material for a base of the piston; and the cold extrusion of the internal contour of the piston, taking into account the dimensions selected. ### Claim 15 (depends on 13) Process according to claim 13, wherein the third process step c) comprises the following partial steps: the rough-turning of an external contour for the piston, with removal of material in what will subsequently be the conical section of the piston; and adaptation of the thickness of material in the form of a shoulder in the region of the ball end which is to be shaped. ### Claim 16 (depends on 13) Process according to claim 13, wherein the fifth process step e) comprises the following partial steps: the installation of at least one bore in the neck region of the piston; the filling of the clearance in the piston with a suitable fluid; the installation of a longitudinal bore with a restrictor in the pin; the installation of grooves for piston rings in the region of the base of the piston; and the hardening and grinding of said piston. ### Claim 17 Piston for an axial-piston engine of the inclined-axis type, said piston comprising an elongate conical section, a neck region formed at the narrower diameter end of said elongate conical section, a ball end having a cavity provided therein, said ball end being formed onto said neck region, a clearance which is constructed in the piston, and a pin which is constructed to extend in said clearance, wherein the wall of the piston formed by said clearance has different thicknesses of material in different sections of its axial length, the thickness of the material of the wall of the piston in the region of the cavity in the ball end being greater than the wall thickness in the elongate conical section. ### Claim 18 (depends on 17) Piston according to claim 17, wherein said elongate conical section, at the larger diameter end thereof, extends into a base of said piston having a greater wall thickness than the remaining axial extent of the elongate conical section. ### Claim 19 (depends on 18) Piston according to claim 18, wherein said remaining axial extent of the elongate conical section has a uniform wall thickness between said base and said neck region. ### Claim 20 (depends on 18) Piston according to claim 18, wherein said clearance has a radially decreasing outer diameter at a closed end portion of said clearance proximate said base so as to form a heavier wall thickness at the larger diameter end of said elongate conical section. ### Claim 21 (depends on 20) Piston according to claim 20, wherein at least one circumferential groove is formed in said base proximate said heavier wall thickness for receiving a piston ring. ### Claim 22 (depends on 21) Piston according to claim 21, wherein two said grooves are formed in said base in parallel spaced relationship, each said groove having a piston ring receivable therein.