# US 2013/0152901 A1 · Multi-cylinder spark ignition engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0152901 A1 - Document ID: US20130152901A1 - Status: Published application - Kind: A1 - Application number: 13/818,051 - Filed: 2011-06-27 - Published: 2013-06-20 - Earliest claimed: 2010-08-21 - Assignees: Mazda Motor Corporation - Inventors: Kouji Shishime; Junsou Sasaki; Hideki Omori - Web page: https://patentgrep.com/patent/US20130152901A1 ## CPC - F02B 75/04: Engines with variable distances between pistons at top dead-centre positions and cylinder heads - F02D 13/02: during engine operation - F02D 15/00: Varying compression ratio - F02D 41/006: {using internal EGR (control of valve overlap for internal EGR F02D13/0261; arrangements for internal EGR F02M26/01)} - F02D 2200/10: Parameters related to the engine output, e.g. engine torque or engine speed - F02P 5/045: {combined with electronic control of other engine functions, e.g. fuel injection (in general F02D37/02)} - F02P 5/152: dependent on pinking (detecting or indicating knocks in internal-combustion engines G01L23/22) - Y02T 10/12: Improving ICE efficiencies - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract An engine has a geometric compression ratio of higher than 12, and includes an exhaust manifold, a variable exhaust valve timing mechanism, an ignition timing controller, and an effective compression ratio adjuster. The exhaust manifold has a plurality of branched exhaust passages connected to the respective exhaust ports of the individual cylinders; a plurality of first collector segments each of which joins the branched exhaust passages for the cylinders which are not adjacent in the exhaust order sequence; a plurality of middle exhaust passages connected to the downstream of the first collector segments, respectively; and a second collector segment that joins the middle exhaust passages. In at least low and middle speed ranges in a high load region of the engine, the effective compression ratio is set to have a value larger than 10 and the ignition timing is retarded, and the valve opening time of the exhaust valve is changed according to the engine speed so that a predetermined amount of a valve overlap period is ensured and that negative pressure waves from exhaust pressure pulses reach an exhaust port during the valve overlap period in a plurality of engine speed ranges. This effectively reduces knocking in low and middle speed ranges in a high load region of the engine while achieving high torque by keeping the compression ratio high. ## Claims ### Claim 1 A multi-cylinder spark ignition engine having four or more cylinders into which a fuel containing at least gasoline is injected, the multi-cylinder spark ignition engine having a geometric compression ratio of higher than 12, and comprising: an exhaust manifold connected to respective exhaust ports of individual cylinders; a variable exhaust valve timing mechanism for changing a valve opening time of an exhaust valve; an ignition timing controller for controlling an ignition timing of a spark plug provided in each cylinder; and an effective compression ratio adjuster for adjusting an effective compression ratio, the exhaust manifold having a plurality of branched exhaust passages connected to the respective exhaust ports of the individual cylinders; a plurality of first collector segments each of which joins the branched exhaust passages for the cylinders which are not adjacent in the exhaust order sequence; a plurality of middle exhaust passages connected to the downstream of the first collector segments, respectively; and a second collector segment that joins the middle exhaust passages, in at least low and middle speed ranges in a high load region of the engine, an effective compression ratio being adjusted to have a value larger than 10 by the effective compression ratio adjuster, the ignition timing being retarded by a predetermined amount from the MBT by the ignition timing controller, and the valve opening time of the exhaust valve being changed according to the engine speed by the variable exhaust valve timing mechanism so that a predetermined amount of a valve overlap period of an intake valve and the exhaust valve is ensured in a case where the valve opening time and a valve closing time of the intake and exhaust valves are defined with the valve lift of 0.3 mm, and that the negative pressure waves from the exhaust pressure pulses reach an exhaust port of a cylinder during the valve overlap period of that cylinder in a plurality of engine speed ranges. ### Claim 2 (depends on 1) The multi-cylinder spark ignition engine as defined in claim 1, wherein the relation among a cross-sectional area S1 of the branched exhaust passage, a cross-sectional area S2 of the middle exhaust passage, and a cross-sectional area S3 of an exhaust passage located downstream of the second collector segment is defined to be given by (S2/S1)<(S3/S2). ### Claim 3 (depends on 1) The multi-cylinder spark ignition engine as defined in claim 1, wherein a diameter-expanded cavity is provided downstream of the exhaust manifold, the diameter-expanded cavity having a space therein with a larger cross section, the position of the diameter-expanded cavity being determined in such a manner that a positive pressure wave produced immediately after the exhaust valve opening is inverted, in the diameter-expanded cavity, as a negative pressure wave and this negative pressure wave reaches the exhaust port during the valve overlap period in a predetermined first engine speed range on a low engine speed side. ### Claim 4 (depends on 3) The multi-cylinder spark ignition engine as defined in claim 3, wherein a plurality of diameter-expanded cavities are provided downstream of the exhaust manifold, the diameter-expanded cavities having an upstream diameter-expanded cavity and a downstream diameter-expanded cavity located downstream thereof, the negative pressure wave inverted in the downstream diameter-expanded cavity reaching the exhaust port during the valve overlap period in the first engine speed range, the negative pressure wave inverted in the upstream diameter-expanded cavity reaching the exhaust port during the valve overlap period in the third engine speed range that is higher than the first engine speed range by a predetermined amount, and the negative pressure wave from the pressure pulses in the exhaust manifold reaching the exhaust port during the valve overlap period in the second engine speed range between the first engine speed range and the third engine speed range, as well as the fourth engine speed range that is higher than the third engine speed range. ### Claim 5 (depends on 4) The multi-cylinder spark ignition engine as defined in claim 4, wherein the relation between a passage length L1 extending from each cylinder to the second collector segment of the exhaust manifold and a passage length L2 from each cylinder to the upstream diameter-expanded cavity is defined to be given by 3*L1