# US 2006/0137632 A1 · Internal combustion engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2006/0137632 A1 - Document ID: US20060137632A1 - Status: Published application - Kind: A1 - Application number: 11/313,683 - Filed: 2005-12-22 - Published: 2006-06-29 - Earliest claimed: 2004-12-24 - Assignees: Nissan Motor Co., Ltd. - Inventors: Shunichi Aoyama; Katsuya Moteki; Shinichi Takemura - Web page: https://patentgrep.com/patent/US20060137632A1 ## CPC - F02B 41/04: in main cylinders - F02B 75/048: {by means of a variable crank stroke length} - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) ## Abstract An internal combustion engine includes a piston reciprocating in a cylinder; a crankshaft; and a multilink piston-crank mechanism linking the piston with the crankshaft. The multilink piston-crank mechanism includes an upper link having a first end connected with the piston by a piston pin; a lower link mounted rotatably on a crankpin of the crankshaft and having a first end connected with a second end of the upper link by a first connection pin; a control link having a first end connected with a second end of the lower link by a second connection pin; a control shaft connected movably with a second end of the control link and configured to rotate in synchronization with the crankshaft and at a half rotational speed of the crankshaft; and a phase adjusting section configured to variably adjust a phase of rotation of the control shaft relative to the crankshaft in accordance with an operating condition of the engine. The multilink piston-crank mechanism is configured to variably control a piston stroke characteristic of the engine. ## Claims ### Claim 1 An internal combustion engine, comprising: a piston reciprocating in a cylinder; a crankshaft; and a multilink piston-crank mechanism linking the piston with the crankshaft and including; an upper link having a first end connected with the piston by a piston pin; a lower link mounted rotatably on a crankpin of the crankshaft and having a first end connected with a second end of the upper link by a first connection pin; a control link having a first end connected with a second end of the lower link by a second connection pin; a control shaft connected movably with a second end of the control link and configured to rotate in synchronization with the crankshaft and at a half rotational speed of the crankshaft; and a phase adjusting section configured to variably adjust a phase of rotation of the control shaft relative to the crankshaft in accordance with an operating condition of the engine, the multilink piston-crank mechanism being configured to variably control a piston stroke characteristic of the engine. ### Claim 2 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the multilink piston-crank mechanism is configured to vary the piston stroke characteristic by varying the phase of rotation of the control shaft relative to the crankshaft through the phase adjusting section. ### Claim 3 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the phase adjusting section is configured to vary the phase of rotation of the control shaft relative to the crankshaft by moving a position of the second end of the control link relative to the control shaft at some point of crank angle. ### Claim 4 (depends on 2) The internal combustion engine as claimed in claim 2, wherein the phase adjusting section is configured to vary the phase of rotation of the control shaft relative to the crankshaft at some point of crank angle, and thereby to vary the piston stroke characteristic. ### Claim 5 (depends on 2) The internal combustion engine as claimed in claim 2, wherein the multilink piston-crank mechanism is configured to vary a compression ratio of the engine by varying the piston stroke characteristic during an intake stroke of the engine. ### Claim 6 (depends on 2) The internal combustion engine as claimed in claim 2, wherein the multilink piston-crank mechanism is configured to vary the piston stroke characteristic to allow a compression ratio of the engine in the case where a distance of piston stroke of the piston during an intake stroke is relatively short, to be higher than the compression ratio in the case where the distance of piston stroke of the piston during the intake stroke is relatively long. ### Claim 7 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the multilink piston-crank mechanism is configured to vary the piston stroke characteristic to allow a volume of a combustion chamber inside the cylinder at an exhaust top dead center of the piston to have a minimum value in the case where a distance of piston stroke of the piston during an intake stroke has a maximum value. ### Claim 8 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the multilink piston-crank mechanism is configured to vary the piston stroke characteristic to allow a distance of piston stroke of the piston during an expansion stroke to become longer as the distance of piston stroke of the piston during an intake stroke becomes shorter. ### Claim 9 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the multilink piston-crank mechanism is configured to vary the piston stroke characteristic to allow a distance of piston stroke of the piston during an intake stroke to be shorter when the operating condition of the engine is under a low load condition, as compared to the distance in the case where the operating condition of the engine is under a high load condition. ### Claim 10 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the multilink piston-crank mechanism is configured so that the piston stroke characteristic is approximate to simple harmonic motion on the supposition that the rotation of the control shaft is in a stopped state. ### Claim 11 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the piston pin and the first connection pin have a substantially equal axial distance to each other. ### Claim 12 (depends on 1) The internal combustion engine as claimed in claim 1, wherein the crankshaft includes a counterweight having an outermost portion which crosses an imaginary extension line extended from the piston pin in an axial direction of the piston pin, when the piston is located in proximity of a bottom dead center. ### Claim 13 An internal combustion engine, comprising: a piston reciprocating in a cylinder; a crankshaft; and piston-crank linking means for linking the piston with the crankshaft and including; upper linking means having a first end connected with the piston; lower linking means mounted rotatably on a crankpin of the crankshaft and having a first end connected with a second end of the upper linking means; control linking means having a first end connected with a second end of the lower linking means; a control shaft connected movably with a second end of the control linking means and configured to rotate in synchronization with the crankshaft and at a half rotational speed of the crankshaft; and phase adjusting means for variably adjusting a phase of rotation of the control shaft relative to the crankshaft in accordance with an operating condition of the engine, the piston-crank linking means being configured to variably control a piston stroke characteristic of the engine.