Abstract: A dual mode fuel injector having first (15) and second (30) valve members. The valve members are actuatable independently of one another and are arranged to open in opposite directions. The valve members control the flow through first (18) and second (29) orifices, one of which injects the fuel at a narrow angle with respect to the injector axis, and the other of which injects the fuel at a wider angle with respect to this axis.

Abstract: An engine of reciprocating piston type includes a cylinder block (4) with one or more cylinders (2), each of which receives a respective piston (10) and is defined by a respective cylinder barrel (8), which is integral with the reminder of the cylinder block. The outer surface of each cylinder barrel (8) carries a plurality of substantially circumferential discontinuous reinforcing ribs, each comprising a plurality of elongate projections (12) spaced apart by gaps (14). Each projection (12) in each rib is in registry with a gap in the or each adjacent rib, when viewed in the direction of the length of the associated cylinder barrel.

Abstract: A method of assembling a bearing house for a rotary shaft, such as a camshaft, comprising a bearing cap secured to a relatively massive component, such as a cylinder head. The bearing cap and the massive component afford respective semi-circular recesses which cooperate to define a circular hole in which the rotary shaft may be received. The method comprises connecting the bearing cap to the massive component, deforming at least spaced portions of the bearing cap into intimate contact with the massive component so as to produce a unique relocation position, boring the circular hole in the bearing cap and the massive component, removing the bearing cap, inserting the shaft into the semi-circular recess afforded by the massive component and reconnecting the bearing cap to the massive component.

Abstract: A direct injection gasoline engine includes at least one cylinder, a piston reciprocably mounted within the cylinder, a cylinder head closing the cylinder and at least one inlet port adapted to cause swirl of the inlet air in the cylinder substantially about the axis of the cylinder. The crown of the piston is provided with a recess which has a floor and a side wall and constitutes at least part of the combustion chamber. A spark plug extends close to or into the recess, at the top dead centre position of the piston, at a position adjacent to the side wall of the recess. A fuel injector is arranged to inject fuel into the recess and is situated adjacent the side wall of the recess. That portion of the side wall of the recess which is between the fuel injector and the spark plug is arcuate, when viewed in the axial direction of the cylinder.

Abstract: A crankcase scavenged two-stroke engine includes a piston reciprocably mounted in a cylinder. The cylinder wall has an exhaust port and a rear transfer port opposed thereto formed in it. The rear transfer port communicates with the interior of the crankcase via a rear transfer passage and is arranged to open before the exhaust port closes, whereby, in use, the cylinder is scavenged. An inlet duct is arranged to supply combustion air to the crankcase and a throttling valve is arranged to throttle the flow of air through the inlet duct. A carburettor is arranged to supply fuel into the inlet duct. The interior of the crankcase is divided into at least two separate crankcase volumes, a rich volume (V1,V2) and a lean volume (V3). Each crankcase volume communicates with the cylinder via a respective hole in the crankcase wall. The cylinder wall also has at least one lateral transfer port formed in it at a position between the rear transfer port and the exhaust port.

Abstract: An engine of reciprocating piston type includes a cylinder block which defines one or more cylinders and connected to which is a cylinder head closing the cylinders. Each cylinder reciprocably receives a respective piston and is defined by a respective cylinder barrel which is integral with the remainder of the cylinder block only at one or both ends. The remainder of the length of the cylinder barrel is spaced from the remainder of the cylinder block in the radial direction by a gap which constitutes a cooling passage. The wall of the cylinder barrel affords a plurality of circumferentially spaced ribs extending in the longitudinal direction of the cylinder lining over at least a proportion of its length.

Abstract: A differential drive mechanism comprises a cage (1), which is rotatable about an axis (3) and represents the input, two coaxial output shafts (12, which are rotatable in respect of the cage (1) about the axis (3), a coupling (4) which is connected eccentrically through two output shafts (12) to transmit relative contra-rotational movement between them by connections which permit relative rotation of the coupling (4) and the output shafts (12). The eccentric connection of the coupling (4) on the ouput shafts (12) includes a respective eccentric hole (9) in the inner end (10) of each output shaft (12) in which the associated end (6) of the coupling (4) is received. The ends (6) of the coupling (4) have a part-spherical engagement surface. A slipper (8) affording a complementary part-spherical internal surface is received in each eccentric hole (9) and each engagement surface is in engagement which a respective complementary internal surface.

Abstract: A hydraulic tappet comprises an open-ended cylinder and a piston slidably accommodated in the cylinder. One end of the piston projects out of the open end of the cylinder and engages a valve rocker. A gear mechanism is provide to effect rotation of the cylinder about its axis whilst the piston remains stationary. An oil chamber is provided within the cylinder beyond the other end of the piston. A pressurized oil space is arranged to supply oil to the chamber via a non-return valve. An oil discharge space communicates with the chamber via a pathway including an opening in the cylinder wall. The pathway is interrupted by the piston as the piston moves into the cylinder. The oil discharge space is at a pressure substantially below that of the pressurized oil space. A plurality of spaced holes is arranged in a spiral line formed in the cylinder wall but only one of the holes communicates with the oil discharge space at any one time.

Abstract: A two-stroke engine of crankcase scavenged type includes a piston reciprocably mounted in a cylinder, an exhaust port, an inlet port arranged to supply combustion air to the crankcase and a transfer port comprising two or more transfer passages extending between the crankcase and the cylinder. The transfer port is arranged to open before the exhaust port closes whereby, in use, the cylinder is scavenged. Fuel metering means communicates with at least one but not all of the transfer passages and is arranged to supply fuel into the said transfer passage at a rate which is directly determined by the mass flow rate of air through the inlet port. The fuel metering means includes a metering valve connected to actuating means, which is arranged to modulate the valve in response to the mass flow rate of air through the inlet port and fuel supply means arranged to supply pressurised fuel continuously to the metering valve.

Abstract: A differential drive mechanism comprises a cage, which is rotatable about a first axis and represents the input, two coaxial output shafts which are rotatable with respect to the cage about the first axis, a coupling which is connected eccentrically to the two output shafts to transmit relative contra-rotational movement between them by connections which permit relative rotation of the coupling and the output shafts about a second axis parallel to the first axis and a restraint member which is coupled to the cage and to the coupling such that the coupling is rotatable with respect to the cage about a third axis perpendicular to the axis and capable of reciprocation in a direction perpendicular to the first axis but prevented from movement in a direction parallel to the first axis. The eccentric connections are constituted by a respective eccentric hole in the inner end of each output shaft in which the associated end of the coupling is received.

Abstract: A fuel injection for use in a diesel engine and adapted to inject two different fuels sequentially comprises a body including an injection nozzle defining one or more injection orifices, a main fuel supply passage and a pilot fuel supply passage which includes a first non-return valve arranged to prevent fuel flowing in it away from the injection nozzle. The nozzle is controlled by a valve needle which affords a surface directed towards the injection orifice(s) and exposed to a fuel supply gallery. The body contains a cylinder which slidably receives a piston. The main fuel passage communicates with the cylinder adjacent one end thereof and the pilot fuel passage communicates with the cylinder adjacent the other end thereof and with a first outlet passage which communicates with the fuel gallery and includes a second non-return valve arranged to prevent fuel flowing from the fuel gallery into the pilot fuel passage.

Abstract: A spark ignited engine of the type employing exhaust gas recirculation and stratification of the recirculated exhaust gas. The engine has at least one cylinder accommodating a piston and communicating with at least one inlet port cooperating with an inlet valve for inducing air into the cylinder, and at least one exhaust port cooperating with an exhaust valve for discharging exhaust gas from the cylinder. The engine is operated such that the recirculated exhaust gas is induced alone into the cylinder through the inlet port during a part of the engine operating time whereby recirculated exhaust gas and air are introduced through the same port, though at different times.

Abstract: Valve gear for an internal combustion engine includes a first cam mounted to rotate about a first axis, a second cam mounted to rotate about a second axis which is substantially parallel to the first axis, a phase-change mechanism arranged selectively to vary the phase of one of the cams relative to the other, a cam follower which has first and second contact surfaces arranged to be engaged by the first and second cams, respectively. The profile of the first cam includes an ascending portion to move the valve member in a second direction opposite to the first direction and a descending ramp to control movement of the cam follower with respect to the valve member. The profile of the second cam includes a descending portion to control movement of the valve member in the first direction and an ascending ramp to control movement of the cam follower with respect to the valve member.

Abstract: A reciprocating-piston internal combustion engine with catalytic combustion has associated with the or each cylinder a swirl-promoting precombustion chamber in the cylinder head connected to the space in the cylinder above the piston by an inclined transfer passage formed in a "hot plug" inserted in a well in the head. A catalytic screen preferably comprising a platinum gauze extends across the top of the hot plug with its peripheral margin wrapped around the hot plug and trapped between the plug and the cylinder head. The plug has an open-topped recess formed in its upper side, into which recess the transfer passage leads, the recess constituting the lower part of the precombustion chamber and the catalytic screen separating this recess from the remainder of the interior of the precombustion chamber above the screen. An injector injects liquid fuel into the precombustion chamber above and parallel to the catalytic screen.

Abstract: A cast cylinder head for a reciprocating-piston i.c. engine is formed with helical inlet ports at least 50% of the internal surface area of each of which is afforded by a machined surface or surfaces. Each such port may be formed in two machining operations, in one of which the inlet duct is machined and in the other of which the bowl is formed with a cylindrical lower portion and a hemispherical upper portion. A recess may be machined in a third operation in one side of the bowl. The inlet duct may be lined by a liner sleeve at least over its inner end portion, the inner end of the sleeve protruding into the bowl as a swirl barrier. Alternatively the port may be formed asymmetrically by numerically-controlled machining, a barrier lip being formed as a part of the machining operation.

Abstract: A reciprocating-piston i.c. engine is supported on a supporting structure by means of mountings which are attached, not to the crankcase wall, but to the main bearing structure of the engine, by means of rigid support members which extend through flexibly-sealed apertures in the crankcase wall and are rigidly secured to the main bearing blocks. The crankcase wall is thus isolated from vibrations generated by internal moving parts of the engine, and the deformations of the crankcase by such vibrations, and hence the level of noise generated by the crankcase wall, are reduced. Where a longitudinal stiffening beam is secured to the bottom bearing blocks of the main bearing structure, some of the rigid supports of the mountings may be attached to the stiffening beam.

Abstract: An instrument for measuring the air/fuel mixture strength supplied to e.g. an I.C. engine comprises a primary catalytic reactor having a matrix of annular cross-section in whose bore is housed a secondary catalytic reactor and a zirconia oxygen sensor. Propane gas or other hydrocarbon fuel is mixed with air and the mixture passed through the primary reactor and catalytically combusted. A flow of the combustion products of the catalytic reaction is withdrawn and mixed with an equal flow of the engine exhaust gases, and the mixture is passed over the secondary reactor (heated by the primary catalytic reaction) to oxidize its oxidizable constituents, and the products of this secondary reaction are passed over the zirconia sensor (heated by the primary catalytic reaction) for measurement of the oxygen content. The output signal of the zirconia sensor is processed electronically and supplied to a digital indicator giving a direct reading of the equivalence ratio of the mixture supplied to the engine intake.

Abstract: An internal combustion engine of reciprocating-piston type with injection of liquid or gaseous hydrocarbon fuel, provided with catalytic means for initiating the combustion of the air/fuel charge in the combustion chamber of the or each cylinder. The major part of the combustion chamber of each cylinder is afforded by a recess formed in the piston crown, and a catalytic element of mesh, grid, perforated or sintered or other construction, is carried by the piston in a position at least partly overlying the said recess, the fuel being injected into the said recess to contact and pass through the catalytic element, being ignited by its contact with the catalytic element.