Patent GB-1280585-A (GB)
Title: Internal-combustion engine exhaust system
IPC: F02B27/06
Filed: 1970-10-30
Abstract: 1280585 Rotary-piston engine KMF DEVELOPMENT CORP 30 Oct 1970 51664/70 Heading F1F To ensure complete scavenging of spent combustion gases from a rotary piston I. C. engine of the type in which a pair of intermeshed rotors, 10, 12 mounted for rotation about perpendicular axes 22, 24 in a housing 25 and having peripheral lobes 14, 16 and 18, 20 alternatively functioning both as pistons and as cylinder heads during the combustion cycle such that each intake charge of air is carried in a cavity 34 between the lobes 14, 16 for compression at the meshing intersection of the rotors 10, 12 from where it is forced into a combustion chamber 44, fuel being injected therein from a supply 37 and ignited by a pair of sparking- plugs 45 so that the resulting combustion acts within and on the housing 25; a side surface of the rotor 10 (on which it has no driving effect); and a radial end surface of the rotor 12 which accordingly acts as a piston and is rotatably driven to provide output drive via a gear drive 48, the piston/cylinder head roles of the rotors 10, 12 alternatively changing during intermesh thereof to provide output drive from both rotors 10, 12 via the gear drive 48, each rotor exhausts via ports 30, 32 which merge at a junction 49 to exhaust via a tailpipe 51, the exhaust ports each being formed with a variable convergent-divergent orifice nozzle 58, centrifugally controlled according to engine speed, which may be used singly, or in conjunction with a vane-valve 174 forming a closure valve-convergent-divergent orifice at the junction 62, the convergent-divergent orifices serving in known manner to accelerate the exhaust gases from the combustion chamber whereby the exiting gases produce a vacuum in the chamber ready for re-charging with air for the next cycle. The variable convergent-divergent orifice nozzles 58 each include a pair of opposed facing throat members 80, 82 pivoted at 84, 86 and equally pivotally adjusted to vary the throat 66 by a pair of eccentrics 88, 90, arranged in elongated slots 96, 98, and driven by shafts 92, 94 from a rack 115, Figs.3 and 4, axially moved in response to the outward centrifugal movement of weighted bell-crank levers 128 carried by a shaft 118 driven from the gear drive 48 of the engine, centrifugal movement of the rack 115 being opposed by a coil spring 158 adjacent a flexible-rolling- diaphragm 154 to dampen oscillations of the rack. The position of the control vane 180 of the valve 174 is controlled by a panel 184 contained in a chamber 186 provided to accommodate a swinging motion by the panel 184 concurrent with the vane 180 movement, the opposed sides of the chamber 186 being vented oppositely to the passages 72, 74 by ducts 192, 194 respectively, so that when the vane 180 is urged upwardly by exhaust flow from passage 72, a partial vacuum occurs in the passage 74 which vacuum is supplied to the lower side of panel 184 through duct 194 to additionally hold the valve in its upper position, and viceversa when the exhaust flow is subsequently from the passage 74. The exhaust ports are additionally provided, after the converging-diverging nozzle section 58, with a section 60 containing somewhat canted annular internal circumferential slots functioning somewhat in the manner of the well known Maxim firearm silencer to avoid a rapid re-entry of air upon creation of the vacuum and thus reduce the shock wave of gas flow through the exhaust port structure.