GB2149007A - I.C. engine with compressed and heated mixture supply - Google Patents

Abstract

The fuel/air mixture delivery from the pumping cylinders (D1, D2) flows through a heat exchanger and a delivery chamber to the inlets (V3) of a plurality of working cylinders (W1, W2, W3, W4). The exhaust from these working cylinders is discharged to atmosphere via the heat exchanger. Liquid fuel is vapourized in a vapourizer located in a sump of the engine whereby the oil in the sump is cooled by the latent heat of evaporation of the fuel. The vapourized fuel is then conveyed to the carburettor where it is mixed with air and passed to the cylinders (D1, D2). The engine may have a plurality of banks of horizontal radial cylinders with one bank of mixture pumping cylinders and the remainder working cylinders. One end of the engine crankshaft drives the rotor (96, Figs. 6 and 7) of a spark distributor and the other drives the impeller (81, Fig. 5) of a lubricant pump. The cylinder inlets and outlets are controlled by piston slide valves (48, Fig. 4) operated by rockers (45) engaging cams (64) on the crankshaft. <IMAGE>

Description

SPECIFICATION Improvements in engines This invention relates to engines and is particularly concerned with an engine having efficient use of fuel in order to reduce fuel consumption for a given power output.

With conventional engines, a great deal of the energy gained from the fuel is dissipated in heat which is allowed to escape by being cooled in a radiator or emitted with exhaust gases. This represents wasted energy which is not used to drive equipment, such as a vehicle, which the engine is intended to drive.

If this lost heat energy could be converted to mechanical energy, the engine would be more efficient and there would be considerable savings in fuel costs.

The primary aim of the present invention is to provide an engine which utilises the heat generated to increase the mechanical power output from the engine and/or to reduce the fuel consumption for a given power output.

According to the invention, there is provided an engine which comprises at least three cylinders, wherein the output from one cylinder is connected via a heat exchanger to the inlets of at least two other cylinders, the exhaust outputs from said other cylinders being vented to atmosphere via said heat exchanger, said one cylinder serving merely to deliver an inducted fuel/air mixture without igniting the same and said heat exchanger serving to heat said fuel/air mixture by recovery of heat from the exhaust gases.

Thus, the otherwise wasted heat of the exhaust gases is utilised according to the invention to pre-heat the fuel/air mixture in order to provide more efficient combustion in the said other cylinders.

The ratio of working combustion cylinders to predelivery cylinders is desirably two to one but the invention is not restricted to this ratio.

Preferably, the engine is provided with more than three cylinders provided that the desired ratio of working combustion cylinders to pre-delivery cylinders is maintained.

A delivery chamber is desirably located between the heat exchanger and the working cylinders, said chamber serving as a reservoir in respect of the pressures generated in the fuel/air mixture by the delivery cylinder and heat exchanger for onward transmission to the working cylinders.

According to a preferred embodiment of the invention, the engine takes the form of a radial engine having at least three banks or blocks of cylinders, the cylinders extending radially in each block and the cylinders in one block serving as delivery cylinders and the cylinders in the other blocks serving as working combustion cylinders.

A vapourizer may be located in the sump of the engine, said vapourizer being arranged to receive a supply of liquid fuel when the engine is in operation, said fuel being vapourized by the heat of the engine oil in the sump and, at the same time, serving to cool said oil, and said vapourizer being further connected to means leading to the inlet of said delivery cylinder or block of cylinders.

The engine according to the present invention can with advantage be incorporated in a radial engine of the kind disclosed in British Patent Specification No. 2024938.

Accordingly, in a preferred arrangement, an engine according to the present invention comprises at least three cylinder blocks each having the same number of cylinders and in which the outputs from the cylinders of one cylinder block are connected via a heat exchanger to the inlets of the cylinders of the other cylinder blocks, the exhaust outputs from the cylinders of said other cylinder blocks being vented to atmosphere via said heat exchanger, the cylinders of said one cylinder block serving merely to deliver an inducted fuel/air mixture without igniting the same and said heat exchanger serving to heat said fuel/air mixture by recovery of heat from the exhaust gases, wherein each cylinder block comprises a plurality of radially extending cylinders of equal cubic capacity, a respective piston reciprocally mounted in each of said cylinders, a crank bearing ring to which each of the pistons is pivotally connected and a crankshaft arranged to be driven by the crank bearing ring, said crank bearing ring being mounted on a crank of the crankshaft for rotation relative to said crank and being provided with gear teeth engageable with a first gear, and wherein the first gear and a second gear are mounted for common rotation about the same axis, the second gear is engageable with a third gear rotatably mounted on the crank and the third gear is engageable with an internally toothed fixed gear mounted in the engine casing.

Preferably, the first, second and third gears are rotatably mounted on the crank of an adjacent cylinder block.

Each cylinder is desirably provided with a valve member slidably mounted in a valve housing adapted to be clamped to the cylinder between its upper end and a cylinder head therefor, the valve housing and cylinder head being provided with aligned inlet and exhaust bores and/or ports and the valve member being slidably movable to bring bores therein selectively into and out of alignment with the bores in the valve housing.

Preferably, the valve member is operatively connected to a rocker lever arranged to actuate said valve member in response to crankshaft rotation and, desirably, the rocker levers of each cylinder block are urged by respective springs against a common cam surface formed on the associated crank of the crankshaft.

With this arrangement, the cam surface of said one cylinder block is desirably arranged to cause each associated rocker lever to move the respective valve member to permit alignment of a first bore therein with the inlet bore in the cylinder head when the associated piston moves from TDC to BDC and to move the respective valve member to permit alignment of a second bore therein with the exhaust bore in the cylinder head when the associated piston moves from BDC to TDC, the second bore in the valve member being out of alignment with the exhaust bore when the first bore is in alignment with the inlet bore and the first bore in the valve member being out of alignment with the inlet bore when the second bore is in alignment with the exhaust bore.

Further, the cam surface of each of said other cylinder blocks is desirably arranged to cause each associated rocker lever to move the respective valve member to permit alignment of a first bore therein with the exhaust bore in the cylinder head when the associated piston moves from BDC to TDC, to move the respective valve member to permit alignment of a second bore therein with the inlet bore in the cylinder head when the associated piston moves from TDC to half way on its down stroke and to move the respective valve member to a position in which neither of its bores are in alignment with the bores in the cylinder head when the piston moves from half way on its down stroke to BDC, the second bore in the valve member being out of alignment with the inlet bore when the first bore is in alignment with the exhaust bore and the first bore in the valve member being out of alignment with the exhaust bore when the second bore is in alignment with the inlet bore.

The invention will now be further described, by way of example, with reference to the drawings, in which: Figure 1 shows, diagrammatically, one arrangement of an engine according to the invention; Figure 2 is a diagrammatic linear representation of parts of one embodiment of an engine according to the invention; Figure 3 is a longitudinal section through one embodiment of an engine according to the invention; Figure 4 is a transverse section through one cylinder and part of the crankcase of the engine shown in Fig. 3; Figure 5 is a section through an oil pump which is arranged to be located in the sump of the engine and secured to one end of the crankshaft; Figure 6 is a vertical section through one embodiment of a distributor for use in the engine according to the invention; and Figure 7 is a plan view of the distributor shown in Fig. 6.

Reference will first be made to Fig. 1 of the drawings in which the engine consists of six cylinders D1. D2, W1, W2, W3 and W4. In this illustrated arrangement, each of the cylinders has a two stroke working cycle but is provided with inlet and exhaust valves. Inlet valves V1 of the cylinders D1 and D2 are connected by a fluid line to a carburettor via a manual shut-off valve V8. The carburettor is provided with an air filter and a throttle control lever as well as a fuel line which is supplied from a fuel source such as a tank.

The fuel passes along the fuel line via a nonreturn valve V6 to a vapourizer which is located in the sump of the engine. After being vapourized in the vapourizer, the fuel can pass through a valve V5 to the carburettor which has a valve V7 controlled by the throttle control lever.

Exhaust valves V2 of the cylinders D1 and D2 are connected by a delivery line which passes through a heat exchanger and is connected to the inlet of a delivery chamber. This chamber also has an outlet connected to an induction line which leads to inlet valves V3 of the cylinders W1, W2, W3, W4. Exhaust valves V4 lead from these cylinders to an exhaust manifold which is connected to an exhaust line leading to the heat exchanger.

After passing through the heat exchanger, exhaust gases can be vented to atmosphere via an exhaust outlet. This outlet may be provided with one or more silencers if desired or if required by law.

The valves Vi take the form of non-return valves which are open from the top dead centre to bottom dead centre positions of the pistons in the associated cylinders D1 and D2.

Similarly, the valves V2 also take the form of non-return valves but these valves are open from the bottom dead centre to top dead centre positions of the pistons in the associated cylinders D1 and D2. The valves V1 and V2 may be operated by a suitable timing mechanism or by the effects of pressure in the associated cylinders, the valves V1 being arranged to open in response to suction or a reduction in pressure in the cylinders and the valves V2 being arranged to open in response to an increase in pressure in the cylinders. As shown in Fig. 1, the cranks of the pistons in the cylinders D1 and D2 are spaced apart by 180 so that when one piston is at TDC the other is at BDC. Accordingly, when valve V1 in cylinder Di is open, valve V2 in cylinder D2 is also open. At the same time, valve V2 in cylinder Dl is closed and valve V1 in cylinder D2 is closed.

The valves V3 and V4 are arranged to be operated by a suitable timing mechanism with the valves being normally closed and the valves V3 being arranged to be opened from TDC to half way down to BDC and the valves V4 being arranged to be opened from BDC to TDC of the pistons in the associated cylinders.

Ignition is arranged to take place in the cylinders W1, W2, W3 and W4 when the valves V3 are closed during the down stroke of the pistons. These cylinders therefore constitute the working cylinders of the engine while the cylinders D1 and D2 constitute delivery cylinders for delivery the charge to the working cylinders.

In operation, when the engine is switched on, the normally closed valves V5 and V8 are opened and fuel is supplied to the carburettor.

The engine must be turned over by a starter motor until one of the working cylinders W1, W2, W3 and W4 fires when the engine can then be allowed to run up to its normal working temperature. It should be noted that the fuel/air mixture in the delivery cylinders D1 and D2 is not ignited. The fuel/air mixture expelled from the cylinders D1 and D2 will be heated as it passes through the heat exchanger. However, since the delivery chamber and the lines leading thereto and therefrom have a fixed volume, the heated gases in the heat exchanger cannot expand and therefore their pressure must be increased. This increased pressure will assist in driving the pistons in the working cylinders W1-W4 during the down stroke.The ignited exhaust gases issuing from the exhaust valves V4 will be at a higher pressure and temperature than the inlet gases supplied from the delivery chamber but these gases will be cooled as they pass through the heat exchanger by heating the fuel/air mixture which is being supplied to the delivery chamber.

The pistons of all of the cylinders are mounted on a crankshaft having cranks alternating at 180 so that the pistons in cylinders D1, W1 and W3 are at TDC when the pistons in cylinders D2, W3 and W4 are at BDC and vice versa.

The delivery chamber is desirably provided with a thermostat connected to an electric immersion heater and arranged to switch on the heater if the temperature in the chamber falls below a predetermined value and to switch off the heater when the temperature in the chamber exceeds a second predetermined value. The thermostat and heater may be required for cold starting conditions.

The vapourizer acts as a heat exchanger by taking heat from hot oil in the engine sump.

This will serve not only to cool the engine to prevent over-heating but will also serve to pre heat the fuel and to vapourize the same. If the pressure of vapourized fuel in the vapourizer exceeds a predetermined value, the non-return valve V6 is closed by this excess pressure to prevent the vapourizer fuel from escaping back to the fuel tank. Similarly, the valve V5 prevents vapourized fuel from escaping from the vapourizer when the engine is not run ning.

Pressure acquired in the delivery chamber as a result of heat exchanged from the exhaust gases in the heat exchanger works against the delivery of fuel mixture by two piston surface areas in the delivery cylinders but the pressure works in favour of four piston surface areas in the working cylinders. Hence, the principles of fluid dynamics work in favour of the engine with the ratio of working cylinders to delivery cylinders, assuming all cylinders to be of equal size. Volumetrically, two delivery cylinders will exactly fill four working cylinders with induction of half down stroke.

The pressure to drive the crankshaft must therefore come from the delivery chamber as a result of heat gained and converted to mechanical force, being the difference between the working cylinders and the delivery cylinders. After half of the down stroke of the pistons in the working cylinders, the pressure in the cylinders, even though the internal heat energy of the fuel mixture drives the crankshaft by moving the cylinders down to BDC, adds to the drive force by being allowed to expand from half down stroke to BDC. The excess heat energy and pressure is passed into the exhaust line to the heat exchanger.

All the heat energy ultimately comes from the internal heat energy of the fuel mixture. The hotter the engine, the more heat is exchanged and the greater the pressure in the delivery chamber. It would appear that the engine would get very hot indeed and pressure in the delivery chamber would get very high. This would give rise to immense power in the engine and very high revolutions of the crankshaft. Clearly, once a desired power output from the engine and crankshaft revolution has been achieved, the fuel in the mixture can be reduced by that amout of internal heat energy equivalent to the heat gained in the heat exchanger. The heat gained is thus converted to mechanical energy and, as a result, considerable savings in fuel consumption can be achieved.

Even though as much fuel may be supplied to the engine as is required to ensure that there is no fuel starvation, vapourization of the fuel before mixing reduces the density of the fuel in the mixture which although it reduces the volumetric efficiency of induction having already expanded under the action of the suction created in the delivery cylinders and by gaining latent heat of evaporation, nevertheless increases fuel efficiency of consumption by ensuring that the fuel mixture is not too dense and providing a considerable gain in the conversion of internal heat energy in the fuel to mechanical energy to drive the engine.

The delivery chamber serves as a reservoir to moderate variations in heat and pressure as pressure waves are pushed into the system by pistons of the delivery cylinders.

Let us now imagine piston in one of the delivery cylinders moving from BDC to half up stroke and the pistons in two of the working cylinders moving from TDC to half down stroke, the cylinders being of equal size. The half volume of the delivery cylinder has to occupy two half volumes of the working cylinders. The expansion can only come from the delivery chamber, that is to say that the heat exchanger has made the fuel mixture in the delivery system gain mechanical energy in that the half volume of one delivery cylinder is converted to twice that volume for the working cylinders. In such a closed system it could be said that pressure from the delivery chamber at that time acts on one piston surface in a delivery cylinder opposing motion and on two piston surfaces in the working cylinders for creating motion.There is therefore a resultant force equivalent to pressure acting on one piston in favour of motion from TDC to half down stroke of the working cylinders. The realization that half volume from one delivery cylinder must expand and yet have the same pressure to fill twice its volume in working cylinders at half down stroke itself suggests motion for then and only then can the expanded volume occupy that space. After half down stroke, even though no more fuel mixture enters the two working cylinders, the pressure of hte mixture in the cylinders still has sufficient energy left to expand. With this energy and the internal heat energy of the fuel mixture which is ignited at half down stroke as soon as the inlet valves V3 are closed, the pressures of the expanding gases push the pistons down to BDC.Meanwhile, the piston in the delivery cylinder pushes the remaining half volume from half up stroke to TDC into the delivery system, working against motion and increasing the pressure in the delivery chamber which pressure then acts in favour of motion in the other two working cylinders after they have passed TDC and their inlet valves V3 are opened. Any excess heat is recycled back to the delivery chamber through the exhaust heat exchanger and converted to pressure for driving the working cylinders. The amount of fuel in the fuel mixture can be controlled in the carburettor to give only that amount of internal heat energy converted to mechanical energy for motion which is required to maintain a steady state of the engine.

The heat exchanger, delivery chamber, delivery line, induction line and exhaust line should desirably be insulated to prevent the loss of heat. Assuming the insulation and the heat exchanger to be efficient, then at steady state: ElF = PO+ LM + HLJ + HLE where ElF = Internal heat energy of fuel P0 = Power output of engine LM = Internal mechanical losses of engine HLl = Heat losses through insulation Hole= = Heat losses through exhaust outlet.

To increase the efficiency of fuel consumption it becomes clear that the insulation and heat exchanger must be efficient. If the heat losses were negligible, it could be said that the power output from the engine was equal to the internal heat energy of the fuel less the internal mechanical losses of the engine.

The valve V8 is provided in the line leading from the carburettor to the delivery cylinders D1 and D2 in order to ensure that the heat and pressure are retained by the engine after switching off and are not wasted to the atmosphere. With efficient insulation, the so retained heat and pressures can be used to advantage when the engine is re-started. A further valve (not shown in Fig. 1) may be provided in the exhaust line for the same reason.

The engine according to the invention may take various forms but one example will now be described in detail with reference to the remaining figures of the drawings. This engine consists of six cylinder blocks each having five cylinders of equal bore and stroke length. Two of the cylinder blocks serve as delivery cylinder blocks while the remainder serve as working cylinder blocks. The ratio of working cylinders to delivery cylinders is therefore maintained at 2:1.

The cylinders in each cylinder block are radially arranged about the crankcase and are equally spaced apart by 72". The cylinders in adjacent working cylinder blocks are radially displaced by 18 , which represents the angle of consecutive cylinder firing, forming a staggered angular arrangement in the cylinder blocks. This arrangment is illustrated diagrammatically in Fig. 2 which shows one cylinder from each cylinder block staggered by 18" with respect to the corresponding cylinder in adjacent cylinder blocks.It will be seen that the cylinders in the delivery cylinder blocks are also radially displaced or staggered by 18 so that the pistons in the first delivery cylinder block DB1 will reciprocate in corresponding manner to the pistons in the third working cylinder block WB3 and the pistons in the second delivery cylinder block DB2 will reciprocate in corresponding manner to the pistons in the fourth working cylinder block WB4. The cranks in adjacent cylinder blocks are displaced from one another by 180'.

For a given distance from the centre of the crankshaft, which is also the centre of the engine, the stagger line of the cylinders in adjacent blocks forms a definite helix angle with the crankshaft axis. For a distance of 200mm, the stagger line forms an angle of 48 48' 1G" with the crankshaft axis. Therefore, if 200mm is the distance of centre lines of induction and exhaust pipes made to follow the stagger line of cylinders, the induction and exhaust pipes each form a helix angle of 48 48' 10" with the crankshaft axis.The feed lines of fuel mixture to the two delivery cylinder blocks are branched out by manifolds and are connected to the cylinders through the valves associated with the induction strokes, that is to say those valves which are open when the pistons move from TDC to BDC. The feed lines leaving the cylinders converge by manifolds to form the delivery line. These delivery feed lines are connected to the working cylinders via a heat exchanger (not shown) and the fuel mixture ignited in these cylinders is expelled out through the valves associated with the exhaust strokes, that is to say those valves which are open when the pistons move from BDC to TDC.The induction lines of the fuel mixture to the four working cylinder blocks are similarly branched out by manifolds and connected to the cylinders through the associated inlet valves, that is to say those valves which are open when the pistons move from TDC to half down stroke. Similarly, the exhaust lines are connected to the cylinders and the gases are let out through the exhaust valves, that is to say those valves which are open when the pistons move from BDC to TDC. The exhaust pipes from each cylinder also converge to manifolds.

The two adjacent sides of the cylinders each have an ear or a lug 11 through which pass precisely fitting bolts 1 2 to hold and secure the cylinder blocks to internally toothed gear plates 1 3 located between the cylinder blocks, said bolts serving to link the stagger line of the cylinders from one end to the other of the engine. At each end of the engine casing, each gear plate 1 3 is also bolted by means of bolts 1 5 to end cover plates 14 of the engine casing.It will thus be seen that while there are only six cylinder blocks, there are seven toothed gear plates 1 3. In between the cylinders in each cylinder block are created sufficiently wide gaps through which sprays of oil, formed by movement of the crankshaft and the crank gears, are freely allowed to pass to lubricate and cool parts outside the cylinders.

Each of the toothed gear plates 1 3 takes the form of a ring clamped between two adjacent cylinder blocks or between a cylinder block and an end cover plate 14 of the engine casing and is provided with an offset inner region which forms an internally toothed gear ring 1 6 as shown in Fig. 3. The pitch circle diameter of each gear ring 1 6 is 1 G9mm and it has 82 teeth.

As shown in Fig. 3, the engine has a crankshaft comprising a rod 20 extending throughout the length of the engine and mounted in bearings 1 7 located in the end cover plates 14. An end cap 1 8 is provided on one of the end cover plates, the crankshaft projecting through the end cap and a seal 1 9 in the form of a washer being provided in the end cap and engaging the crankshaft rod 20.

This end of the crankshaft carries a distributor 29.

The engine is desirably arranged vertically, as shown in Fig. 3, and the distributor 29 is mounted on the upper end of the crankshaft.

Eight crank parts 21 to 28 are mounted on the crankshaft inside the engine casing formed by the adjacent cylinder blocks, said cranks alternating at 180 in the cross-sectional plane. The lower end of the crankshaft carries a collar or sleeve 31 which is secured to the crank part 28 by means of screws 32 and which carries a bevel gear 33. The bevel gear 33 is arranged to drive a pair of bevel gears 34 and 35, the gear 34 leading to the engine transmission and the gear 35 being arranged to drive ancillary equipment such as a pump and/or a generator. A nut 38 engages with a screw-thread on the crankshaft adjacent its upper end to hold the crank parts 21 to 28 together.The rod 20 has a hollow bore 36 to allow the passage of lubricating oil which is pumped from the sump 37 at the bottom of the engine by the oil pump up through the crankshaft to a series of radial bores provided in said crankshaft throughout its length. The oil is allowed to drain back down to the sump lubricating the engine parts as it does so. Alternatively, the rod 20 may be provided with one or more axial grooves in its peripheral surface for the same purpose of delivering lubricating oil to the engine parts.

This latter arrangement may be preferred in the interests of strength and cheapness.

The cylinder blocks DB1, DB2, WB1, WB2, WB3 and WB4 are encased within a cylindrical cover or casing 39 which extends between the end cover plates 1 4 and is secured thereto by means of bolts 41 passing through bores in flanges 40 at the ends of the casing 39 and engaging in screw-threaded bores in the plates 14.

Each cylinder 42 of each cylinder block is provided with a pair of projections 43 separated by a slot and having aligned transverse bores for the reception of a pivot bolt 44 (see Fig. 4). A rocker lever 45 is pivotally mounted on the pivot bolt 44 so as to be movable in the slot and a hair spring 46 is arranged to act on the lever 45 to force a lobe 47 on one end thereof against an associated crank part 22, 23, 24, 25, 26 or 27. The other end of the rocker lever 45 is pivotally connected to a slide valve 48. As shown in Fig. 3, the projections 43 and the slot therebetween are inclined with respect to the axis of the associated cylinder 42 whereby the rocker levers 45 are also inclined to the axes of the associated cylinders. This is necessary in order to ensure that the rocker levers do not interfere with the rotation of the crankshaft or reciprocation of the pistons.

The slide valve 48 is reciprocally mounted in a valve plate 49 which is provided with a passageway for receiving the slide valve as well as with aligned throughgoing bores which extend through the valve plate being interrupted at the points at which they intersect the passageway. The valve plate is further provided with a screw-threaded bore for receiving a spark plug 51.

The slide valve 48 is a good sliding fit in the passageway in the valve plate and also has two bores extending transverse to its longitudinal axis which bores are so spaced apart that only one bore can be aligned with a respective bore in the valve plate 49 at any one time. The end of the slide valve 48 is forked and a pivot pin 52 extends between the forks being pivotally mounted in transverse bores in the said forked end of the slide valve. There is a further bore in the pin itself through which slides the said other end of the rocker lever 45.

The valve plate 49 is secured to the end of the cylinder 42 by means of a cylinder head 53 and head bolts 54 which are passed through aligned bores in the cylinder head 53 and valve plate 49 and engage in screwthreaded bores in the wall of the cylinder 42.

The upper surface of the cylinder head 53 is radiussed so that the inner surface of the cylindrical cover 39 can bear against said cylinder head. The cylinder head is further provided with a bore for receiving the spark plug 51, which extends out of the cover 39 through an aligned bore therein, and with two further bores which are aligned with the throughgoing bores in the valve plate 49.

These latter bores are screw-threaded and one receives a screw fitting 55 which extends through the cover 39 and which is connected to an inlet manifold (not shown) connected to the induction line from the delivery chamber while the other bore receives a screw-fitting 56 which also extends through the cover 39 and which is connected to an exhaust manifold (not shown) connected to the exhaust line.

The other cylinders are provided with like valve mechanisms and cylinder heads and are thus all encased within the cylindrical cover or casing 39. The cover or casing may be provided with a lining of heat-insulating material if desired in order to maintain the engine at its working temperature for considerable periods after use.

A respective piston 57 is reciprocally mounted in each of the cylinders 42 and is connected by a respective connecting rod 58 to an associated crank bearing ring 59. The crown of each piston is desirably provided with a sunken region to accommodate the spark plug 51 at top dead centre. Fig. 4 shows a single connecting rod 58 connected to the crank bearing ring 59 but in actual fact five connecting rods for each cylinder in the associated cylinder block will be pivotally connected to the crank bearing ring at equispaced angles around said ring. A crank bearing ring 59 is provided for each of the six cylinder blocks and these rings are mounted on the crank parts 22 to 27 as shown in Fig.

3.

The crank part 21 at the upper end of the engine does not carry a crank bearing ring but it is secured to the adjacent crank part 22. As shown in Fig. 4, the crank part 22 has a central bore for receiving the crankshaft rod 20. The crank bearing ring 59 is mounted on a cylindrical part 61 of the crank part the axis of which is eccentrically displaced with respect to the axis of the crankshaft rod 20. A groove 62 extends from the bore for the crankshaft to the periphery of the part 61 and a radial bore is provided in the crankshaft at this point to permit the passage of oil for lubrication purposes. The part 61 of the crank part 22 is further provided with two bores 63 which are aligned with corresponding bores in the crank part 21 so that the crank parts can be secured together by means of bolts (not shown).

The periphery of the central region of the crank part 22 is formed as a cam surface 64 and against which the lobes 47 of the associated rocker levers 45 are urged by the springs 46. On the other side of its central region, the crank part 22 is provided with a second eccentrically arranged cylindrical part 65 provided with bores 66 by means of which the crank part 22 can be secured to the crank part 23 by bolts (not shown). This side of the crank part 22 also carries a double pinion comprising a small pinion 67 and a larger pinion 68 which are rotatably mounted on a shaft 69 fixed in the crank part 22 as well as a further pinion 71 which is rotatably mounted on a shaft 72 fixed in the crank part 22 and the teeth of which are in mesh with the teeth of the pinion 68.The pinion 71 is also meshed with the teeth of the gear ring 1 6. The pinion shafts 69 and 72 are desirably screw-threaded and engaged in screwthreaded bores in the associated crank parts, the shaft 69 having a left-hand thread and the shaft 72 having a right-hand thread.

As shown in Fig. 3, the crank bearing ring 59 takes the form of a sleeve having a flange atone end on which the connecting rods 58 are pivotally mounted. The other end of the sleeve is provided with a gear ring 73 which, in the case of the crank part 22, is arranged to mesh with the small pinion 67 rotatably mounted on the crank part 21. The crank part 21 also carries the pinions 68 and 71 which are arranged in similar manner to the corresponding pinions shown in Fig. 4 on the crank part 22. As previously stated, the gear ring 1 6 has 82 teeth. The gear ring 73 on the crank bearing ring also has 82 teeth while each of the pinions 67, 68 and 71 has 30 teeth.

As shown in Fig. 4, the piston 57 is just before half way on its upward stroke at which point the plane of the crankshaft with cranks alternating at 180 is perpendicular to the axis of the cylinder 42. While the crank part 22 is actually at half return throw, the piston is not at half stroke. The position of the piston at half down stroke is likewise not coincidental with the position of the crank part 22 at half forward throw. This is because of the swing of the connecting rod 58. The lateral swing of the connecting rod is shown as at half return throw of the crank for the upward stroke of the piston, that is to say that in Fig. 4 the crankshaft 20 is rotating in a clockwise direction.

The crank parts 23, 24 and 25 for the other working cylinder blocks are assembled in a similar manner to the crank part 22. The crank part 26 is also similar except that the cam surface is different to provide different degrees of valve opening as will be hereinafter more fully described. The crank part 27 is similar to the crank part 26 except that this part does not carry the pinions 67, 68 and 71. The crank part 28 is bolted to the crank part 27 and has a cylindrical extension piece for receiving the collar or sleeve 31. The crankshaft 20 is provided with a series of radial bores opposite each of the crank parts 21 to 28 for the passage of oil for lubrication purposes. It is necessary to construct the cranks as separate parts in order to fit the crank bearing rings 59 to each of the crank parts 22 to 27 before these parts are assembled together.

Secured to the lower end of the crankshaft 20 is a centrifugal pump which is shown in Fig. 5 of the drawings. This pump comprises a cylindrical valve casing 74 which is internally screw-threaded at one end for engagement with a corresponding screw-thread provided on the end of the crankshaft 20 (not shown in Fig. 5). The other end of the valve casing 74 tapers to a hollow shaft 77 which is screw-threaded at its end remote from the casing to receive a disc-shaped impeller 81 carrying rotor blades 82. The shaft 77 has a radial bore 78 adjacent its screw-threaded end which communicates with an axial bore 79 in the shaft leading into the valve casing 74.

Said casing is provided with a conical valve seat 75 and a ball valve member 76 is arranged to seat thereon to seal off the axial bore 79.

The impeller 81 is located in a housing 83 having an aperture 84 in its bottom and mounted by means of bolts 85 on pillars 86 which are secured to and which extend from the bottom wall 87 of the sump. The housing 83 is closed at the top by a lid 91 which is secured to the housing 83 by screws 92 and which contains a number of spring-loaded blow valves 93. A resilient seal 94 is provided on the shaft 75 and is secured in an aperture in the lid 91.

When the engine is in operation, rotation of the crankshaft will cause the impeller 81 to rotate to draw oil from the sump into the housing 83 and thence force the oil via the bores 78 and 79 past the valve member 76 into the valve casing 74 and up the bore or grooves in the crankshaft rod 20. The valve member 76 will prevent oil from draining back down the crankshaft into the sump when the engine is stopped. The blow valves 93 are arranged to open, against spring force, when the pressure in the housing 83 exceeds a predetermined value in order to prevent excessive pressures from building up in the engine.

The seal 94 may also be arranged to be forced away from the shaft to reduce pressurized oil to the sump for the same purpose of keeping the pressure in the housing 83 below a predetermined safe level.

The sump is provided with a drain plug 88 in its bottom wall 87 and a vapourizer 89 extends across the sump as shown in Fig. 5.

The vapourizer serves to cool the oil in the sump in the region at which said oil is drawn into the housing 83 through the aperture 84.

At the same time, fuel in the vapourizer is heated and vapourized as described above with reference to Fig. 1. Thus, excess heat of the engine is used to vapourize the fuel and the latent heat of evaporation of the fuel serves simultaneously to cool the oil and hence the engine. The vapourizer therefore constitutes a heat exchanger and its effectiveness is dependent on its surface area exposed to the hot oil in the sump. The vapourizer pipe or tube 89 leaves the sump connected to connectors (not shown) which are secured in bores in the side walls of the sump and effectively sealed.

The distributor 29 mounted on the upper end of the crankshaft is illustrated in detail in Figs. 6 and 7. As will be seen from these figures, the upper end 95 of the crankshaft projecting from the nut 38 has a reduced diameter with respect to the remainder of the crankshaft and a rotor 96 is mounted on the end of this reduced diameter portion 95 by means of a nut 97. The rotor 96 is housed in a casing 98 containing a bearing 99 for the portion 95 of the crankshaft. A series of twenty fixed electric contacts 101 are mounted in the casing 98 each serving for a respective one of the working cylinders 1 to 20 of the engine. Similarly, a corresponding series of twenty movable contacts 102 are also mounted in the casing 98, each movable contact being associated with a respective fixed contact 101.The pairs of contacts are spaced apart from each other by 18 around the casing 98. The rotor 96 carries a cam lobe 103 which is arranged to act on each of the movable contacts in turn as the crankshaft rotates to close the contacts and to deliver a firing impulse to the spark plug of each of the working cylinders of the engine in turn through every 18 of rotation of the crankshaft. The top of the casing 98 is closed by a cover 104.

It should however be noted that the invention is not restricted to the distributor shown in Figs. 6 and 7 of the drawings and other means for ignition of the engine may be provided if desired, for example, electronic ignition means.

As previously described, the cam surfaces of the crank parts 22, 23, 24, 25, 26 and 27 are engaged by the lobes 47 of the rocker levers 45 mounted on the cylinders of the associated cylinder blocks. When the crankshaft is rotated, each rocker lever is arranged to actuate the associated slide valve 48. In the case of the four working cylinders, the rocker lever 45 of each cylinder is arranged to move the slide valve 48 to a position in which one of its bores is aligned with one of the bores in the valve plate 49 and with the bore in the cylinder head 53 leading to the exhaust fitting 56 when the associated piston is at BDC. The rocker lever is held in this position until the piston reaches TDC.At this point, the cam surface 64 on the associated crank part is effective to move the rocker lever 45 so that said rocker lever moves the slide valve 48 to move said one bore out of alignment with the bores in the valve plate 49 and cylinder head 53 leading to the exhaust fitting 56 and, at the same time, to move the other bore in the slide valve 48 into alignment with the other bore in the valve plate 49 and the bore in the cylinder head 53 leading to the inlet fitting 55. The rocker lever 45 is maintained in this position for half of the piston stroke when the cam surface 64 is effective to move the rocker lever again this time causing the slide valve 48 to be moved out of alignment with all of the bores in the valve plate 49 and cylinder head 53 so that both the inlet and the exhaust valves are closed.It is at this point that the spark plug 51 is ignited to ignite the mixture in the cylinder.

When the piston reaches BDC, the cam surface 64 is again effective to move the rocker lever 45 to the position in which it is effective to move the said one bore in the slide valve 48 into alignment with the bores in the valve plate 49 and cylinder head 53 leading to-the exhaust fitting 56 and the two-stroke cycle is repeated.

The operation of the rocker levers 45 and slide valves 48 mounted on the cylinders of the delivery blocks is similar but in this case the profiles of the cam surfaces on the crank parts 26 and 27 are different so that the other bore in the slide valve 48 is in alignment with the bores in the valve plate 49 and cylinder head 53 leading to the inlet fitting 55 throughout the movement of the associated piston from TDC to BDC.

As previously mentioned, the twenty working cylinders are so arranged that one cylinder fires for every 18 of crankshaft rotation. The cranks in adjacent cylinder blocks are displaced by 180 and the different firing intervals are achieved by staggering the cylinders in each cylinder block by 1 8D with respect to the adjacent cylinder blocks. The cylinders in the first delivery cylinder block DB1 are in phase with the cylinders in the third working cylinder block WB3 and the cylinders in the second delivey cylinder block DB2 are in phase with the cylinders in the fourth working cylinder block WB4.

It should however be noted that the present invention is not restricted to an engine having five cylinders in each cylinder block nor to four working cylinder blocks and two delivery cylinder blocks. The engine may have any suitable number of cylinders provided that the desired ratio of working cylinders to delivery cylinders is maintained. While this ratio is preferably 2:1, it should be noted that this is not an essential requirement of the invention.

Further, although the disposition of the cylinders in a radial configuration is preferred, this also is not essential.

By way of example, an engine may have eight working cylinder blocks and four delivery cylinder blocks, each cylinder block having ten cylinders. The eight working cylinders will have a consecutive cylinder firing sequence angle of 4.5 . The adjacent working cylinder blocks may be displaced by 4.5 stagger to give an alternatingly linear cylinder block firing sequence relative to the crankshaft or may be arranged using the formula S = D X G as specified in British Patent Specification No. 2024938 in which S is the angle in degrees by which the cylinders of each cylinder block are staggered with respect to the cylinders in adjacent cylinder blocks, D is the firing interval between consecutive cylinder firings and G is the gap in cylinder blocks between consecutive cylinder firings.In such a case, D = 4.5 and G = 5 or 3 so that S = 4.5' x 5 = 22.5' or 4.5' X 3 = 13.5' having the sum of stagger angle in a cylinder block of 22.5 + 13.5 = 36 which is the angle of radial spacing in a cylinder block.

The adjacent working cylinder blocks may now be displaced by either the stagger angle of 22.5 or 13.5 to give an alternatingly scattered cylinder firing sequence of 1, 6, 3, 8,5,2, 7,4 or 1,4, 7, 2, 5,8,3,6 respectively relative to the crankshaft in which the cranks are alternating at 180 in a plane.

Clearly, if the cylinders were standardized to specific sizes, to accommodate ten such cylinders in a radial block would subsequently impose a demand on the radial cylinder blocks to be made peripherally larger compared to a cylinder block with only five such cylinders.

Conversely, if the peripheral size of the cylinder block were to remain the same, the size of the ten cylinders would have to be reduced compared to the size of cylinder when only five cylinders are employed.

It would be desirable to have as many cylinders as possible in each cylinder block since all of the cylinders in a block share the same crank bearing ring and its associated crank pinions, reducing the percentage of internal mechanical losses per cylinder and thereby making each cylinder independently more efficient so as to increase the theoretical efficiency of the engine. Increasing the number of cylinders would also not only increase the potential power output of the engine but would, in addition, reduce the number of crank parts of the crankshaft required, since all of the cylinders in a block share a common crank cam, thereby reducing production costs.

The minimum number of working cylinder blocks is two to one delivery cylinder block with as many cylinders in each block as required to achieve a desired power output and subject to limitations regarding space in both vertical and horizontal dimensions.

The main purpose of radial spacing of the cylinders in a block and the stagger of the cylinder blocks is to achieve as uniform as possible running of the engine since a cylinder fires after no more than a few degrees of crankshaft rotation, the angle depending on the number of working cylinders employed in the engine.

Claims (21)

1. An engine which comprises at least three cylinders, wherein the output from one cylinder is connected via a heat exchanger to the inlets of at least two other cylinders, the exhaust outputs from said other two cylinders being vented to atmosphere via said heat exchanger, said one cylinder serving merely to deliver an inducted fuel/air mixture without igniting the same and said heat exchanger serving to heat said fuel/air mixture by recovery of heat from the exhaust gases.

2. An engine according to claim 1, wherein a delivery chamber is located between the heat exchanger and the said other cylinders, said chamber serving as a reservoir in respect of pressures generated in the fue I/air mixture by the said one cylinder and the heat exchanger for onward transmission to the said other cylinders.

3. An engine according to claim 1 or claim 2, wherein said engine takes the form of a radial engine having at least three banks or blocks of cylinders, the cylinders extending radially in each block and the cylinders in one block serving as delivery cylinders and the cylinders in the other blocks serving as working combustion cylinders.

4. An engine according to any preceding claim, wherein a fuel vapourizer is located in the sump of the engine, said vapourizer being arranged to receive a supply of liquid fuel when the engine is in operation, said fuel being vapourized by the heat of the engine oil in the sump and, at the same time, serving to cool said oil, and said vapourizer being further connected to means leading to the inlet of said one cylinder or block of cylinders.

5. An engine comprising at least three cylinder blocks each having the same number of cylinders and in which the outputs from the cylinders of one cylinder block are connected via a heat exchanger to the inlets of the cylinders of the other cylinder blocks, the exhaust outputs from the cylinders of said other cylinder blocks being vented to atmosphere via said heat exchanger, the cylinders of said one cylinder block serving merely to deliver an inducted fuel/air mixture without igniting the same and said heat exchanger serving to heat said fuel/air mixture by recovery of heat from the exhaust gases, wherein each cylinder block comprises a plurality of radially extending cylinders of equal cubic capacity, a respective piston reciprocally mounted in each of said cylinders and a crank bearing ring to which each of the pistons is pivotally connected, the engine crankshaft being arranged to be driven by the crank bearing rings of the cylinder blocks, wherein each said crank bearing ring is mounted on a respective crank of the crank shaft for rotation relative to said crank and is provided with gear teeth engageable with a first gear, and wherein the first gear and a second gear are mounted for common rotation about the same axis, the second gear is engageable with a third gear rotatably mounted on the crankshaft and the third gear is engageable with an internally toothed fixed gear mounted in the engine casing.

6. An engine according to claim 5, wherein the first, second and third gears are rotatably mounted on the crank of an adjacent cylinder block.

7. An engine according to claim 5 or claim 6, wherein each cylinder is provided with a valve member slidably mounted in a valve housing adapted to be clamped to the cylinder between its upper end and a cylinder head therefor, the valve housing and cylinder head being provided with aligned inlet and exhaust bores and/or ports and the valve members being slidably movable to bring bores therein selectively into and out of alignment with the bores in the valve housing.

8. An engine according to claim 7, wherein the valve member is operatively connected to a rocker lever arranged to actuate said valve member in response to crankshaft rotation.

9. An engine according to claim 8, wherein the rocker levers of each cylinder block are urged by respective springs against a common cam surface formed on the associated crank of the crankshaft.

10. An engine according to claim 9, wherein the cam surface of said one cylinder block is arranged to cause each associated rocker lever to move the respective valve member to permit alignment of a first bore therein with the inlet bore in the cylinder head when the associated piston moves from TDC to BDC and to move the respective valve member to permit alignment of a second bore therein with the exhaust bore in the cylinder head when the associated piston moves from BDC to TDC, the second bore in the valve member being out of alignment with the exhaust bore when the first bore is in alignment with the inlet bore and the first bore in the valve member being out of alignment with the inlet bore when the second bore is in alignment with the exhaust bore.

11. An engine according to claim 9 or claim 10, wherein the cam surface of each of said other cylinder blocks is arranged to cause each associated rocker lever to move the respective valve member to permit alignment of a first bore therein with the exhaust bore in the cylinder head when the associated piston moves from BDC to TDC, to move the respective valve member to permit alignment of a second bore therein with the inlet bore in the cylinder head when the associated piston moves from TDC to half way on its down stroke and to move the respective valve member to a position in which neither of its bores are in alignment with the bores in the cylinder head when the piston moves from half way on its down stroke to BDC, the second bore in the valve member being out of alignment with the inlet bore when the first bore is in alignment with the exhaust bore and the first bore in the valve member being out of alignment with the exhaust bore when the second bore is in alignment with the inlet bore.

1 2. An engine according to any one of claims 8 to 11, wherein the axis of each rocker lever is inclined with respect to the axis of the associated cylinder.

1 3. An engine according to any one of claims 5 to 12, wherein the crankshaft is provided with at least one axial groove in its peripheral surface for delivering lubricating oil from a sump to the cranks and other parts of the engine.

14. An engine according to claim 13, wherein an oil pump is connected to one end of the crankshaft for delivering oil to.said engine parts via the axial groove(s) in the peripheral surface of the crankshaft.

1 5. An engine according to claim 14, wherein the oil pump comprises a centrifugal pump located in the sump of the engine.

1 6. An engine according to claim 14 or claim 15, wherein a non-return valve is mounted at said one end of the crankshaft to prevent oil from returning to the oil pump from the crankshaft.

1 7. An engine according to any one of claims 1 3 to 16, wherein a fuel vapourizer is located in the sump, said vapourizer being arranged to receive a supply of liquid fuel when the engine is in operation, said fuel being vapourized by the heat of engine oil in the sump and, at the same time, serving to cool said oil.

1 8. An engine according to any one of claims 5 to 17, wherein the cylinder blocks are encased in an outer casing.

19. An engine according to claim 18, wherein the casing is provided with a lining of heat-insulating materal.

20. An engine according to any one of claims 5 to 19, which comprises two delivery cylinder blocks and four working combustion cylinder blocks.

21. An engine substantially as described herein with reference to the drawings.