GB1592279A - Internal combustion rotary engines - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO INTERNAL COMBUSTION ROTARY ENGINES (71) We, MURRUMBOOEE LIM ITED, a British Company, of 7 Elm Street, Ipswich, Suffolk, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an internal combustion rotary engine-that is to say, an engine in which a rotor is rotatably mounted within a housing and the combustion of a fuel drives directly the rotor.

The most common form of internal combustion engine is the reciprocating piston engine, and despite its very wide usage, this form of engine has many well-known disadvantages. Apart from matters such as the mechanical complexity of a reciprocating piston engine and the difficulties of balancing the moving parts, one particular disadvantage preventing significant increases in the efficiency of such an engine is that-for a 4-stroke cycle-the compression and ignition strokes have essentially the same compression (or expansion) ratios. Though the precise ratios can be adjusted relative to one another to a very small extent by suitable design ob the valve overiap, it is nevertheless a significant limitation on the maximum efficiency obtainable from a reciprocating piston engine.This is because the volume of the exhaust gases, when reduced to the ambient temperature and pressure, are very much greater that the volume of the initial charge of fuel gas, at ambient temperature and pressure, and so when the exhaust gases are scavenged they are hot and still not at ambient pressure; considerable unused energy remains in those gases. In an attempt to increase the engine efficiency, turbo-chargers are sometimes used to extract energy from the exhaust gases but such arrangements are extremely costly and so far are thought only to be worthwhile on large commercial vehicles employing engines operating on the Diesel cycle.

In an attempt to overcome the above mentioned disadvantages, several forms of rotary engine have been designed but so far these have met with either no or very limited commercial success. Many of the designs make no significant increase in the relative ratios of the compression and expansion strokes of the cycle of operation and so no significant increase in efficiency is obtained, even though there may be less mechanical complexity.

Other engines have met with insuperable difflculties concerning sealing or have such mechanical complexity or out-of-balance masses rendering the production of useful, practical working engines almost impossible.

It is a principal aim of this invention to provide a rotary engine which at least reduces some of the disadvantages discussed above of known forms of internal combustion en gine such as reciprocating piston engines.

According to this invention, there is pro vided an internal combustion rotary engine comprising a housing defining a generally cylindrical chamber, and a rotor mounted for rotation in one direction coaxially within the chamber with the ends of the rotor sub stantially sealing against the end faces of the chamber, the rotor being provided with at least one pair of angularly-spaced radially extending lobes the outermost tips of which substantially seal against the cylindrical wall of the chamber and the circumferential wall portions of the rotor between the lobes being generally arcuate and each having a centre of curvature co-incident with the rotor axis, one of the lobes of the or each pair thereof being provided. with a pair of ports one port facing the direction of rotation and the other port facing away from the direction of rotation, each port separately communicating with an associated passageway formed within the rotor which passageway in turn communicates with an associated duct formed in the housing at least at certain relative angular positions of the rotor and housing, the passageways and ducts together constituting inlet and exhaust tracts for the engine, the engine further com prising a combustion cell having a port communicating with the chamber and a pair of gates pivotally mounted on the housing about axes parallel to the axis of the cylindrical chamber with one gate adjacent each side of the combustion cell, each gate being movable to and from a first position in which the gate forms a part of the cylindrical wall of the chamber and the tips of the lobes may pass sealingly thereover and a second position in which the gate extends across a partannular space between the cylindrical wall of the chamber and an adjacent arcuate wall portion of the rotor between the lobes so as substantially to seal against that arcuate wall portion, the end faces of the chamber and the cylindrical wall of the housing, there being means to actuate the gates between their two positions in a timed relationship to the rotation of the rotor such that fuel gas may be drawn into the part-annular space between the rotor and the housing trailing said one lobe through said other port of the one lobe, compressed into the combustion cell by the other lobe of the or each pair thereof and then ignited to drive the trailing face of said other lobe and finally exhausted through said one port of said one lobe.

It will be appreciated that the rotary engine of this invention operates on the 4-stroke cycle, and that by appropriate positioning of the lobes on the rotor and the gates, the ratio of the compression ratio to the expansion ratio can be made as high as 4 : 1, though more typically 2 : 1. This allows practically all of the expansion energy of the burning fuel gases to be extracted for useful work, as well as giving cool running. As the combustion of the fuel is thus more complete, the operation is much cleaner, giving minimal pollution.

The principal parts of the rotary engine of this invention are the housing and the rotor rotatably mounted within the cylindrical chamber defined by the housing. The chamber preferably has a planar end face for ease of manufacture, but other shaped end faces could be used. The rotor of course must have correspondingly shaped ends (i.e.

side cheeks) so as to be capable of sealing substantially against the end faces of the chamber and the sealing is preferably effected simply by having the rotor a very close fit within the cylindrical chamber. The sealing can be enhanced by means of an oil film between the end faces of the chamber and the ends of the rotor, though in some circumstances it may be advantageous to provide sealing strips fitted either in the end faces of the chamber and bearing on the rotor or fitted within the ends of the rotor and bearing on the end faces of the chamber.

The inlet and exhaust tracts are respectively defined by said other port in said one lobe together with its associated passageway and duct in the housing and by said one port together with its associated passageway and duct. Clearly, some form of substantially gas-tight correction must be made between each passageway and the associated duct, and in order most simply to effect this, it is preferred to arrange for one passageway to open on one end of the rotor and for the other passageway to open on the opposed end of the rotor. The associated ducts can then respectively open into the two opposed end faces of the chamber, so that when in registration, communication is effected between the respective passageways and ducts.Preferably such communication occurs irrespective of the angular position of the rotor in the chamber, and this can be achieved by providing an annular groove in the rotor or in the end face of the chamber-or even in both if required-at the radius of the passageway and duct to be connected together. The ducts in the housing could have a limited angular extent for some embodiments, so that communication is established only when gas is to pass through the ducts. The sealing effect obtained by the fit of the rotor in the chamber may be sufficient to give the required gastight seal between the passageway and the duct, though especially for the case of the exhaust tract, it may be necessary to provide further sealing arrangements, such as a labyrinth seal.Another possibility would be for the two passageways to extend along a shaft supporting the rotor, one passageway to one end of the rotor and the other passageway to the other end of the rotor. The ducts could then be connected to the passageways by means of co-axial, rotable gastight couplings known per se, but if this arrangement is used, a central bore in the shaft cannot be employed for instance for the supply of lubricant to the rotor, in the way commonly employed in engines.

The relative disposition of the lobes on the rotor effects the ratio of the compression ratio to the expansion ratio of the engine.

It is preferred however for the angular spacing between the centres of the two lobes to lie in the range of from 450 to 1500 and a practical embodiment of this invention employs 1300. Typical angular widths of the lobes are 200 at their mean radius.

The engine of this invention described so far is comparable so far as its mode of operation is concerned to a twin cylinder fourstroke engine, insofar as there is one power stroke per revolution of the rotor. In order to obtain more power from the engine, the relative sizes of the component parts may be made larger, but it is preferred to modify the design in order to produce more power pulses per revolution of the engine. This can be achieved in two ways; in one way a second pair of lobes is provided on the rotor, the second pair being opposed and generally similar to the first pair and the ports in the one lobe of the second pair being connected to the same passageways in the rotor as the respective ports of the one lobe of the first pair.This arrangement, without further modification of the rotary engine discussed above, provides two power pulses per revolution of the rotor, and is thus comparable to a fourcylinder, four-stroke reciprocating piston engine of a conventional design. In the other way a second pair ob gates is provided and a second combustion cell located therebetween at a position generally diametrically opposed to the first-mentioned gates and combustion cell, the rotor still having only one pair of lobes. Again, this possibility would provide two power pulses per revolution of the rotor but it does have the disadvantage of increased mechanical complexity.On the other hand, in the design with one pair of gates and combustion cell, the fuel gases, having been drawn into the annular space, are carried around the cylindrical chamber by the rotor for the best part of half a revolution (as will become apparent from the description set out hereinafter with reference to the drawings), without being compressed. The arrangement with two combustion cells and pairs of gates makes more effective use of the available angular movement of the rotor.

A further possibility is of course to combine the advantages of the two possible further arrangements discussed above. Thus, a rotor with two pairs d lobes and a chamber with two combustion cells and two pairs of gates may be assembled to provide an engine giving four power pulses per revolution of the rotor, comparable to an eight cylinder four-stroke reciprocating piston internal combustion engine.

Further possibilities include the use of a rotor with one pair of lobes and three combustion chambers and pairs of gates in the housing, giving three power pulses per revolution of the rotor (comparable to a six cylinder four-stroke reciprocating piston internal combustion engine) and two pairs of lobes on the rotor in conjunction with three combustion cells and pairs of gates, giving six power pulses per revolution of the rotor (comparable to a twelve cylinder four-stroke internal combustion reciprocating piston engine). Yet another possibility, suitable for use at least in conjunction with a rotary engine having a rotor with one pair of lobes and a housing with one combustion cell and as associated pair of gates, is to provide a further gate on its own spaced arcuately from the combustion cell.This gate can serve to induce a further charge of fuel gas through the other port of the one lobe, which further charge can then be introduced into the burning and expanding gases driving the other lobe partway through the ignition stroke of the cycle.

Though this counteracts to some extent the advantageous effect of having a relatively large expansion ratio compared to the compression ratio, it does nevertheless increase the power output from the engine by an effect some what comparable to supercharging in a con ventional reciprocating piston internal com bustion engine.

The configuration and operation of the engine may be modified to provide three pairs of gates and combustion chambers when em ploying a simple rotor with two lobes, one of which is ported, the three pairs of gates being equi-spaced around the chamber in the hous ing. The operation of the gates should then be controlled so that the combustion cham ber being employed on any particular com bustion stroke is the chamber next to the one used on the preceding stroke in the sense opposed to the sense of rotation of the rotor.

It can be shown that in that way a 'dead' volume of gas is not carried round with rotor for considerable angular movements and that for a given number of revolutions of the rotor, there are 3/2 times as many power strokes. Of course, this modified configuration and opera tion may be yet further modified to incor porate one or more of the possible altematives already mentioned above.

For correct operation of the rotary engine, each gate should be pivotally mounted to the housing at its trailing edge, having regard to the direction of rotation of the rotor. Each gate should also present a curved surface to the interior of the chamber when the gate is in the one position so that the gate is effect forms a part d the cylindrical wall of the chamber and so that the outermost tips of the lobes may pass sealingly thereover. The width of the gate must clearly be such that the gate is a sliding fit between the end faces of the cylindrical chamber. Sealing strips may be provided to enhance the seal there, if re quired.The free edge of each gate remote from its pivotal mounting to the housing is adapted to seal on the arcuate wall portions of the rotor, and by appropriate design of the shapes of the lobes, a gate may be ar ranged to remain in contact with the trailing flank of a lobe as the gate passes from its first position to its second position immedi ately after a lobe has passed over the gate.

A further advantage which can be obtained by appropriate design is that the angle of contact between the free edge of a gate and the rotor may be made substantially constant, irrespective of which part of the rotor the free edge of the gate is contacting, and this allows an effective seal easily to be achieved.

This is to be contrasted with some known designs of rotary engine in which seals have to be made between surfaces which con stantly are changing their angle of contact, sometimes by as much as 900 or even more.

It is advantageous to configure at least the gate against which combustion takes place to have the shape of a sector, considered in the plane normal to its pivotal axis, By making the sector sufficiently large, only the arcuate face of the gate need be subjected to the combustion force. Moreover a vent may be provided to communicate between the volumes against the two radial plane faces (i.e. the 'front' and 'rear' faces) of the sector-shaped gate, so that the two plane faces are subjected to the same pressure. This results in there being no effective pressure difference across the gate, allowing it easily to be moved between its two positions, the combustion force acting on the arcuate face being transferred directly to the pivot of the gate.

In one embodiment of this invention, the gates are operated mechanically by means of cams provided on the shaft of the rotor. However, it is found that in operation of the engine, the gates are moved from one position to the other only when there are very small pressure differences, or even no pressure differences, across the gates, even though when in the second position, the gates may be subjected to considerable loads. In view of this, it is preferred to operate the gates electro-mechanically, for instance by means of solenoids the armatures of which are drivingly connected to the gates. The actuation of the solenoids can then be controlled electronically, for instance from a simple timing disc rotatable with the rotor in conjunction with an optical pick-up detecting the position of the disc.A further advantage of operating the gates electro-magnetically is that the gates may be held in their first position by appropriate switching of the actuating means irrespective of the rotation or the rotor. This feature can be valuable for starting the engine of this invention, insofar as the rotation of the rotor can be established by an auxiliary starter motor and when rotating at a considerable rate the gates may be switched on to commence the four-stroke cycle of operation. In this way, a relatively small and simple starting motor may be used, for it does not have to have sufficient power to drive the rotor through a compression stroke without assistance from the inertia of the rotor. If the engine is to operate on the Diesel cycle, the compression loads can be very thigh and this feature is then even more advantageous.

As mentioned above, the gates are moved to their second position (i.e. to contact the arcuate portions of the rotor to close off a secion of the annular chamber) only when there is a very small pressure differential-or none thereacross. However, when the gates are in their second position, they are subjected to considerable loads and therefore it is preferred for there to be provided a positive lock to retain each gate in its second position when it has been moved there. Preferably, an over-centre locking arrangement is provided, such as a suitable form of toggle mechanism.

The combustion cell is preferably provided within the housing itself, opening into the chamber through the cylindrical wall thereof.

The volume of the combustion cell affects the overall compression ratio of the engine and the cell should be of a sufficiently large size to accommodate virtually all of the induced charge of the fuel gas at the required degree of compression. The actual compression ratio depends upon the precise cycle on which the engine is to operate-and of course compression-ingnition cycles require much higher compression ratios than spark-ignition cycles. For a spark-ignition cycle, the combustion cells would be provided with a sparking plug or similar device to ignite the compressed fuel gas in the combustion cell whereas for a compression-ignition cycle a suitable injector would be provided to inject fuel into the combustion cell when the induced air has been compressed therein.

The housing is conveniently provided with suitable waterways therein to effect cooling both of the housing itself and the rotor, the latter either by conduction or by providing suitable waterways therein. The shaft supporting the rotor may be provided with an impeller pump to assist the circulation of water through the housing. Alternatively, or in addition to such water cooling, the central part of the rotor may be finned to allow cooling by air, a forced draught being provided if required.

By way of example only, certain specific embodiments and arrangements of rotary engine of this invention will now be described, reference being made to the accompanying drawings, in which: Figure 1 is a partial cut-away side view of a first embodiment of rotary engine constructed in accordance with this invention; Figure 2 is a half-sectional view of the rotary engine shown in Figure 1 and taken on line Z-Z on Figure 1; Figure 3 is a half-sectional view of the rotary engine shown in Figure 3 and taken on line W-W on Figure 1; Figures 4A to 4H are explanatory diagrams showing the complete cycle of operation of the engine of this invention; ; Figures 5A to 5F are diagrams showing several different arrangements of rotary engine constructed in accordance with this invention; Figure 6 is a partial cross-sectional view through a second embodiment of rotary engine constructed in accordance with this invention; Figure 7 is a partial cut-away side view of a third embodiment of rotary engine constructed in accordance with this invention; Figure 8 is a half-sectional view taken on line W-W on Figure 7; and Figure 9 is a half-sectional view taken on line Z-Z on Figure 7.

Referring initially to Figures 1 to 3, there is shown diagrammatically a simplified form of first embodiment of rotary engine constructed in accordance with this invention.

This embodiment comprises a housing 10 defining a generally cylindrical chamber 11 in which is mounted a rotor 12 for rotation in the direction d arrow A. The rotor 12 is keyed to a shaft 13, the shaft being supported in suitable bearings (not shown). The rotor takes the form of a casing of generally cylindrical shape, but of a lesser diameter than the internal diameter of the chamber 11 defined by the housing 10, though the casing is provided with two lobes 14 and 15, the former of which will be referred to hereinafter as the "porting lobe" and the latter of which will be referred to hereinafter as the "power lobe".The outermost tips of the lobes 14 and 15 are generally arcuate in shape, and are arranged closely to fit against the cylindrical wall of the housing 10 defining the chamber 11, the wall portions 16 of the rotor 12 between the lobes also being generally arcuate and being centred on the rotor axis. The end faces 17 of the chamber 11 and the end cheeks 18 of the rotor 12 are both generally planar, and the axial width of the rotor 12 is such that it is a close fit between the end faces 17 of the chamber 11.

Means (not shown) are provided to supply oil to between the closely fitting parts of the rotor and the housing, so as to effect a substantially gas-tight seal therebetween. The seal however, relies principally upon the close fit between the adjacent parts.

The porting lobe 14 is provided in its trailing flank 19 (having regard to the direction of rotation of the rotor, shown by arrow A) with an inlet port 20, and is provided in its leading flank 21 with an exhaust port 22. The casing defining the rotor 12 is divided internally by a radial wall 23, the inlet port 20 being to one side of the radial wall 23 whereas the exhaust port 22 is to the other side of the radial wall. The end cheeks 18 of the rotor are cut away in the central regions, so as to provide annular orifices 24 and 25 which orifices respectively communicate directly with the inlet port 20 and the exhaust port 22, via the passageways defined to either side of the radial wall 23.The end faces 17 of the chamber are provided with ducts 26 and 27 opening into the chamber 11 at such a position that the ducts are always in register respectively with the annular orifices 24 and 25, irrespective of the angular position of the rotor within the chamber. The ducts 26 and 27 together with the interior spaces within the rotor, divided by the radial wall 23, thus define the inlet and exhaust tracts for the engine.

At the position shown generally by the reference number 30, the housing 10 is provided with a combustion cell 31 and a pair of gates 32 and 33 one to each side of the cell 31 and each gate 32 or 33 being hinged on a shaft 34 adjacent its trailing edge, having regard to the direction of rotation of the rotor 12. Each gate is individually movable from the position shown in Figure 1 (referred to herein as its "first position") to a second position in which the free edge 32' or 33' of the respective gate bears on the arcuate wall portions 16 of the rotor. The gates are operated by a mechanism (not shown) in the correct timing sequence, having regard to the rotation of the rotor.This mechanism can be purely mechanical, comprising cams mounted on the shaft 13, or driven thereby, with associated followers, or instead the gates may be moved by electro-magnetic solenoids electronically controlled for actuation at the correct times in relation to the rotation ob the rotor 12.

The combustion cell 31 is provided with a port 35 opening into the cylindrical wall of the chamber 11, and a sparking plug 36 protrudes into the cell 3 1 for igniting fuel gas compressed therein. Means (not shown) are provided to provide high tension to the sparking plug 36 at the appropriate time in relation to the rotation of the rotor.

The above-described rotary engine is some what simplified and schematic but is des cribed to show the principles of construction of an engine of this invention. In practice, it would be necessary for the rotary engine to include a cooling system, for example by providing appropriate passages in the walls of the housing through which water may be circulated. Also, lubrication must be supplied as necessary to the various component parts, such as the interface between the rotor and the walls defining the chamber, and to the gates.

The operation of the above-described rotary engine will now be explained in detail, re ference being made to Figures 4A--4H. The rotary engine operates on the four-stroke cycle and produces one power pulse per revolution of the rotor. For each cycle, fuel gas is drawn into the engine through the inlet port 20, subsequently compressed into the combustion cell 31, ignited there to produce a power pulse on the ignition stroke and then exhausted through the exhaust port 22 on a scavenge stroke.

Figure 4A shows the rotary engine at the start of the induction stroke, in which fuel gases are drawn into the engine from a car burettor (not shown) connected to duct 26, through the annular orifice 24 and then through the inlet port 20 in the trailing flank 19 of the porting lobe 14. The gate 32, at the start of the induction stroke, is moved to its second position so that on rotation of the rotor in the direction of arrow A, the volume of space B between the porting lobe 14 and the gate 32 increases, thereby drawing fuel gas into that space, as will be apparent from Figures 4A and 4B. As the power lobe 15 reaches gate 32, the gate is moved back to its first position and a fixed volume of fuel gas is now present in the space B and carried round by the rotor for subsequent compression.At this time, fuel gas drawn into the engine on the previous rotation has been compressed, in a manner to be described below, in the combustion cell 31 and, as shown in Figure 4C, as the power lobe 15 passes over the cell port 35, the compressed gas is ignited. As shown in Figure 4D, immediately after the power lobe 15 has cleared the free edge of gate 33, this commences to move to its second position and shortly afterwards the combustion cell port 35 is opened by the power lobe and the ignition stroke proper can commence, the expanding gases bearing respectively on the gate 33 in its second position and on the trailing flank of the power lobe 15. This power stroke thus drives the rotor round in the direction of arrow A, force being imparted to the trailing flank od the power block.

The power stroke continues as shown in Figures 4E and 4F, and as will be apparent from a consideration of those figures, the power stroke is of very great length relative to the compression stroke, the burning gases being expanded eventually to fill the space indicated by the character C. Throughout this part of the cycle, space B has a fixed volume and carries round the charge of fuel gas previously induced, as shown in Figures 4A and 4B.

On further rotation of the rotor from that position shown in Figure 4F, gate 33 moves to its first position, as shown in Figure 4G and the porting lobe 14 passes thereover. As the porting lobe 14 clears the port 35 to the combustion cell, the charge of fuel gas pre viously induced and in space B can now pass into the combustion cell, on compression.

The power stroke also is completed and the burning gases now have access to the exhaust tract, through the exhaust port 22 in the porting lobe 14. As now shown in Figure 4H, gate 32 moves to its second position immediately after the porting lobe clears its free edge, and very shortly after the rotor and gate are in the position shown in Figure 4A. On continued rotation ob the rotor, the power lobe 15 clears the free edge of the gate 33, and that gate moves to its second position (Figure 4D). The exhaust gases are now forcibly scavenged out of the exhaust port 22 by virtue of the space C between gate 33 and the leading face of the porting lobe reducing in volume on rotation of the rotor.However, the charge of gas carried round in the space B is compressed between the gate 32 and the power lobe 15 into the combustion cell 31, whilst on the other side of the gate 32, an induction stroke has commenced for the next following cycle of operation. The compression continues as shown in Figures 4A and 4B and immediately after the position shown in Figure 4B, the power lobe 15 closes off the port 35 to the combustion cell as the gate 32 moves to its first position. It will of course be appreciated that there is a small volume of highly compressed fuel gas trapped between the power lobe 15 and the gate 32 after the power lobe has closed off the port 35 to the combustion cell and as the gate 32 starts to move to its first position.This is however of no con sequence, for the gas is not lost or otherwise wasted but is simply expanded into the space A of increasing volume on the induction stroke of the next following cycle of operation, and is added to the charge already there.

In a modified form of rotary engine of this invention, it would be possible to provide a further gate and combustion cell at the position shown in broken lines on Figure 4A. This gate can be operated to move to its second position when the rotor is at the position shown in Figure 4D and to remain in its second position until such time as the power lobe is about to contact it. It will be appreciated that on rotation of the rotor from the position shown in Figure 4D this further gate will serve to cause compression into the further combustion cell of the charge drawn into space B in the sequence of Figures 4A to 4C, whilst drawing a further charge into the annular space of increasing volume between the porting lobe 14 and the further gate.After the power lobe has passed over the port to the further combustion cell, the compressed charge therein mixes with the burning gases on the trailing side of the power lobe, and thus is itself ignited to expand and assist the driving of the power lobe. The second charge induced by the further gate is meanwhile carried round for compression into the combustion cell 31, as described above.

The further combustion cell may be provided with a sparking plug to aid the ignition of the charge compressed therein, but this is not essential.

Referring now to Figures SA to SF, there are shown six alternative possible configurations for rotary engines constructed in accordance with this invention. These are only examples and other configurations are possible.

Figure 5A shows the form of engine described above, and thus with a rotor having one pair of lobes, and one combustion cell with an associated pair of gates. Figure SB shows an arrangement with a rotor having two pairs of lobes, one pair being generally opposed to the other pair, but still with one combustion cell and associated pair of gates.

Figure SC shows an arrangement with a rotor similar to that shown in Figure SA, but here two combustion cells are provided, diametrically opposed to one another, each cell having its associated pair of gates. This arrangement avoids carrying the charge of gas in space B (see figure 4) for a considerable part of a revolution without operating on that gas.

However, the expansion on the ignition stroke is not as great in this arrangement. Figure SD shows an arrangement employing the rotor shown in Figure SB and the housing shown in Figure 5C; thus there are two pairs of lobes and two combustion cells each with an associated pair of gates. Figure SE shows a further possibility, in which the housing is provided with three combustion cells, each having its own associated pair of gates, and this arrangement employs the rotor shown in Figure SA. The expansion ratio on the power stroke is again reduced yet further-but it is still greater than the compression ratio.

Figure SF shows the housing of Figure SE, but with a rotor similar to that shown in Figure SB mounted therein, and thus provided with two pairs of lobes. Set out below is a table comparing the various arrangements shown in Figure 5.

Pairs of Lobes Combustion Power pulses Configuration on the rotor Chambers Pairs of Gates per revolution 5A 1 1 1 1 SB 2 1 1 2 SC 1 2 2 2 SD 2 2 2 4 SE 1 3 3 3 SF 2 3 3 6 Referring now to Figure 6, there is shown a partial cross-section through another embodiment of rotary engine constructed in accordance with this invention. This embodiment comprises a housing 50 defining a generally cylindrical chamber 51 and a rotor 52 which is rotatably mounted therewithin. The rotor 52 is supported on and keyed to a shaft 53, carried in plain metal bearings 54, one disposed to each side of the chamber 51. The rotor has the same general shape as that described above with reference to Figures 1 to 3 and similarly the internal shape of the chamber 51 is similar to that described earlier.

The chamber 51 includes a combustion cell 55 in which is mounted a sparking plug 56, and a pair of gates (not shown) are associated with the combustion cell, one to each side of the port connecting the cell 55 to the interior of the chamber 51.

The housing is a complex article, fabricated from castings and other parts so as to provide a series of waterways 57 around the chamber 51. At an appropriate point in the housing 50, to the left (in Figure 6) of the chamber, an inlet passage (not shown) is arranged to allow the introduction of water to the waterways 57. From there, the water passes radially inwardly on the relatively cool side of the engine (insofar as this side of the engine has the inlet tract) and then passes along suitable axial grooves provided in the shaft 53 to reach the relatively warm side of the engine-i.e. the side with the exhaust tract. Mounted on the shaft is a water impeller 59 to assist the circulation of the water, which water then leaves the housing through tapping 60 adjacent the periphery of the housing.

Ducts 61 and 62 are provided in the housing to serve respectively as inlet and exhaust tracts for the engine, duct 61 being formed as a stub on which a carburettor can be mounted and duct 62 leading to an exhaust system. As has been described previously, the ducts communicate with ports provided in the leading and trailing faces of the porting lobe (not shown) of the rotor. In the exhaust duct 62, there is provided a turbine 63, mounted on the shaft 53 for rotation with the rotor 52. The purpose of the turbine is to assist the scavenging of the engine on the exhaust stroke, rather than to attempt to extract power from the exhaust gases.

Oil-ways 64 are provided to lubricate the bearings 54, there being a drilling along the axis of the shaft 53 to allow the feeding of oil to the required places. Addition feeds (not shown) are provided to supply oil to the faces of the rotor which slide over the walls of the chamber 51.

Suitable oil seals 65 and water seals 66 are arranged as necessary to prevent leakages or contamination of one fluid by another.

Also provided on the shaft 53 is a helical gear 67, arranged to drive a distributor (not shown) for supplying high tension to the sparking plug 56 at the required moment.

The same gear may be used to drive an oil pump, or instead a separate oil pump may be driven either directly from the shaft 53 or by an electric motor.

It will be appreciated from the foregoing that a rotary engine constructed in accordance with this invention may display many advantages over conventional forms of reciprocating-piston internal combustion engine and indeed over many known designs of rotary engine. The engine of this invention has a low parts count and the areas subjected to friction and thus wear are small relative to a reciprocating-piston engine of comparable power output. The engine can be made with a relatively large diameter and be intended to operate at low speeds, making it relatively easy to use the power developed, as well as giving good reliability. This feature would make the rotary engine particularly valuable for marine use.

The engine employs a few seals only, and because the free edges of the gates contact the rotor at a substantially constant angle when being used to seal thereagainst, it is relatively easy to design an effective tip-seal which is effective and reliable in operation. When the engine runs, the only out of balance forces are developed by the porting and power lobes, but in view of the nature of construction of the rotor, these may easily be balanced by providing suitable weights within the rotor casing. For a rotor having two pairs of lobes, it is inherently in balance at all times, without the need for further balancing.

For greater power outputs, the overall size of the engine may be increased, or it may be run at a higher speed, producing more power pulses per unit time. Alternatively, one of the constructions giving more power pulses per revolution and described above with reference to Figure 5 may be employed. If yet greater power ourputs are required, two or more housings and rotors may be arranged coaxially on a common shaft. On the other hand, when it is required to employ an engine of very small axial length, the engine need be only slightly longer than the width of the housing plus a suitable power take off arrangement, especially when the gates are operated electro-magnetically.

Figures 7 to 9 show a third embodiment of rotary engine generally similar to that shown in Figures 1 to 3 and like-or closely similar-parts are given like reference characters. This second embodiment differs from that described previously in three significant respects.

As can be seen in Figure 7, the gate 33 of the first embodiment has been modified so as to have a sector-shape when considered in the plane normal to its pivotal axis. This gate 70 is configured such that when the gate is moved to its second position to contact arcuate wall portion 16 of the rotor, only the arcuate wall 71 of the gate is opposed to the lobe 14 (or 15) of the rotor. The other generally radial wall 72 of the gate is arranged to lie within a suitably shaped portion 73 of the housing 10, a passageway 74 venting portion 73 to the 'down stream' side of the chamber 11, having regard to the gate 70.

In this way, the pressure difference across the two generally radial plane faces of the gate can be kept to a minimum, and move ment of the gate greatly eased. The combustion force is applied to the arcuate wall 71, which then is transferred directly to the pivot.

Of course, the radial plane wall od the gate which is presented to the chamber 11 when the gate is in the retracted, one position is not strictly plane, but should be slightly concave so as to be contiguous with the wall of the chamber 11, allowing either lobe 14 or 15 smoothly and sealingly to pass thereover.

The rotor 12 has a modified design as compared to the first embodiment of engine.

Here the rotor is in the form of an outer wall 75 defining the lobes 14 and 15, the arcuate wall portions 16 and end cheeks 18, the outer wall 75 being supported by four spokes 76 integral with a hub 77. Between the spokes 76 are cooling vanes 78, the housing 10 being vented at 79 to allow cooling fluid-and typically air-to be pumped between the vanes 78.

The end cheeks 18 of the rotor are provided with orifices 24 and 25 commtmicating with the ports 20 and 22 in the porting lobe 14 via suitably formed ducts. The housing, at an appropriate radius for registering with the orifices 24 and 25 in the rotor, is provided with ducts 26 and 27 opening through the end faces 17 of the chamber 11, the inlet duct extending part way round the respective end face for the extent required for the inlet stroke and the exhaust duct extending substantially right round the respective end face. In this way, the ports in the rotor may communicate with the ducts in the housing irrespective of the angular position ob the rotor in the housing, the openings through the end faces 17 remote from the orifices 24 or 25 being closed off by the end cheeks 18 of the rotor.

WHAT WE CLAIM IS: 1. An internal combustion rotary engine comprising a housing defining a generally cylindrical chamber, and a rotor mounted for rotation in one direction coaxially within the chamber with the ends of the rotor substantially sealing against the end faces of the chamber, the rotor being provided with at least one pair of angularly-spaced radiallyextending lobes the outermost tips of which

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (24)

**WARNING** start of CLMS field may overlap end of DESC **. Also provided on the shaft 53 is a helical gear 67, arranged to drive a distributor (not shown) for supplying high tension to the sparking plug 56 at the required moment. The same gear may be used to drive an oil pump, or instead a separate oil pump may be driven either directly from the shaft 53 or by an electric motor. It will be appreciated from the foregoing that a rotary engine constructed in accordance with this invention may display many advantages over conventional forms of reciprocating-piston internal combustion engine and indeed over many known designs of rotary engine. The engine of this invention has a low parts count and the areas subjected to friction and thus wear are small relative to a reciprocating-piston engine of comparable power output. The engine can be made with a relatively large diameter and be intended to operate at low speeds, making it relatively easy to use the power developed, as well as giving good reliability. This feature would make the rotary engine particularly valuable for marine use. The engine employs a few seals only, and because the free edges of the gates contact the rotor at a substantially constant angle when being used to seal thereagainst, it is relatively easy to design an effective tip-seal which is effective and reliable in operation. When the engine runs, the only out of balance forces are developed by the porting and power lobes, but in view of the nature of construction of the rotor, these may easily be balanced by providing suitable weights within the rotor casing. For a rotor having two pairs of lobes, it is inherently in balance at all times, without the need for further balancing. For greater power outputs, the overall size of the engine may be increased, or it may be run at a higher speed, producing more power pulses per unit time. Alternatively, one of the constructions giving more power pulses per revolution and described above with reference to Figure 5 may be employed. If yet greater power ourputs are required, two or more housings and rotors may be arranged coaxially on a common shaft. On the other hand, when it is required to employ an engine of very small axial length, the engine need be only slightly longer than the width of the housing plus a suitable power take off arrangement, especially when the gates are operated electro-magnetically. Figures 7 to 9 show a third embodiment of rotary engine generally similar to that shown in Figures 1 to 3 and like-or closely similar-parts are given like reference characters. This second embodiment differs from that described previously in three significant respects. As can be seen in Figure 7, the gate 33 of the first embodiment has been modified so as to have a sector-shape when considered in the plane normal to its pivotal axis. This gate 70 is configured such that when the gate is moved to its second position to contact arcuate wall portion 16 of the rotor, only the arcuate wall 71 of the gate is opposed to the lobe 14 (or 15) of the rotor. The other generally radial wall 72 of the gate is arranged to lie within a suitably shaped portion 73 of the housing 10, a passageway 74 venting portion 73 to the 'down stream' side of the chamber 11, having regard to the gate 70. In this way, the pressure difference across the two generally radial plane faces of the gate can be kept to a minimum, and move ment of the gate greatly eased. The combustion force is applied to the arcuate wall 71, which then is transferred directly to the pivot. Of course, the radial plane wall od the gate which is presented to the chamber 11 when the gate is in the retracted, one position is not strictly plane, but should be slightly concave so as to be contiguous with the wall of the chamber 11, allowing either lobe 14 or 15 smoothly and sealingly to pass thereover. The rotor 12 has a modified design as compared to the first embodiment of engine. Here the rotor is in the form of an outer wall 75 defining the lobes 14 and 15, the arcuate wall portions 16 and end cheeks 18, the outer wall 75 being supported by four spokes 76 integral with a hub 77. Between the spokes 76 are cooling vanes 78, the housing 10 being vented at 79 to allow cooling fluid-and typically air-to be pumped between the vanes 78. The end cheeks 18 of the rotor are provided with orifices 24 and 25 commtmicating with the ports 20 and 22 in the porting lobe 14 via suitably formed ducts. The housing, at an appropriate radius for registering with the orifices 24 and 25 in the rotor, is provided with ducts 26 and 27 opening through the end faces 17 of the chamber 11, the inlet duct extending part way round the respective end face for the extent required for the inlet stroke and the exhaust duct extending substantially right round the respective end face. In this way, the ports in the rotor may communicate with the ducts in the housing irrespective of the angular position ob the rotor in the housing, the openings through the end faces 17 remote from the orifices 24 or 25 being closed off by the end cheeks 18 of the rotor. WHAT WE CLAIM IS:

1. An internal combustion rotary engine comprising a housing defining a generally cylindrical chamber, and a rotor mounted for rotation in one direction coaxially within the chamber with the ends of the rotor substantially sealing against the end faces of the chamber, the rotor being provided with at least one pair of angularly-spaced radiallyextending lobes the outermost tips of which

substantially seal against the cylindrical wall of the chamber and the circumferential wall portions of the rotor between the lobes being generally arcuate and each having a centre of curvature coincident with the rotor axis, one of the lobes of the or each pair thereof being provided with a pair of ports one port facing the direction of rotation and the other port facing away from the direction of rotation, each port separately communicating with an associated passageway formed within the rotor which passageway in turn communicates with an associated duct formed in the housing at least at certain relative angular positions of the rotor and housing, the passageways and ducts together constituting inlet and exhaust tracts for the engine, the engine further comprising a combustion cell having a port communicating with the chamber and a pair of gates pivotally mounted on the housing about axes parallel to the axis of the cylindrical chamber with one gate adjacent each side of the combustion cell, each gate being movable to and from a first position in which the gate forms a pair of the cylindrical wall of the chamber and the tips of the lobes may pass sealingly thereover and a second position in which the gate extends across a part-annular space between the cylindrical wall of the chamber and an adjacent arcuate wall portion of the rotor between the lobes so as substantially to seal against that arcuate wall portion, the end faces of the chamber and the cylindrical wall of the housing, there being means to actuate the gates between their two positions in a timed relationship to the rotation of the rotor such that fuel gas may be drawn into the part-annular space between the rotor and the housing trailing said one lobe through said other port of the one lobe compressed into the combustion cell by the other lobe of the or each pair thereof and then ignited to drive the trailing face of said other lobe and finally exhausted through said one port of said one lobe.

2. An engine as claimed in claim 1, wherein the chamber has a planar end face, the rotor also having planar ends for sealing thereagainst.

3. An engine as claimed in claim 1 or claim 2, wherein one passageway from said one lobe opens on one end d the rotor and the other passageway opens on the opposed end of the rotor.

4. An engine as claimed in claim 3, wherein there is provided an annularly-extending groove in the rotor or in the end face of the chamber at the radius of the passageway and duct to be connected together whereby communication between the passageway and duct may occur for at least an extended arc of movement of the rotor.

5. An engine as claimed in any of the preceding claims, wherein the angular spacing between the centres of the two lobes lies in the range of from 450 to 1500.

6. An engine as claimed in claim 5, wherein the angular spacing between the centres of the two lobes is substantially 1300.

7. An engine as claimed in any of the preceding claims, wherein the angular widths of the two lobes are substantially 200 at their mean radius.

8. An engine as claimed in any of the preceding claims, wherein a second pair of lobes is provided on the rotor, the second pair being opposed to and generally similar to the first pair and the ports in the one lobe of the second pair respectively being connected to the same passageways in the rotor as the respective ports of the one lobe of the first pair.

9. An engine as claimed in any of claims 1 to 7, wherein the housing is provided with three equi-spaced combustion chambers each associated with a pair of gates, so as to give three power pulses per revolution of the rotor.

10. An engine as claimed in any of the preceding claims, wherein a second pair of gates is provided and a second combustion cell located therebetween at a position gen erally diametrically opposed to the firstmentioned gates and combustion cell.

11. A rotary engine as claimed in any of claims 1 to 7, wherein a further gate, on its own, is provided spaced arcuately from the combustion cell, whereby a further charge of fuel gas can be induced through the other port of the one lobe, which further charge can then be introduced into the burning and expanding gases driving the other lobe partway through the ignition stroke of the cycle.

12. A rotary engine as claimed in any of the preceding claims, wherein each gate is pivotally mounted to the housing at its trailing edge, having regard to the direction of rotation of the rotor.

13. A rotary engine as claimed in any of the preceding claims, wherein the free edge of each gate remote from its pivotal mounting to the housing is adapted to seal on the arcuate wall portions of the rotor and on the trailing flank of a lobe as the gate passes from its first position to its second position immediately after a lobe has passed over the gate.

14. An engine as claimed in any of the preceding claims, wherein at least the gate against which combustion takes place is configured to have the shape of a sector, considered in the plane normal to its pivotal axis, whereby only the arcuate face of the gate is subjected to the combustion force.

15. An engine as claimed in claim 14, wherein a vent is provided to communicate with the volumes against the two radial plane faces of the sector-shaped gate when the gate is in the second position, so that there is no effective pressure difference across the gate when in its second position.

16. An engine as claimed in any of the preceding claims, wherein the gates are operated mechanically by means of cams provided on or mechanically coupled to the shaft of the rotor.

17. An engine as claimed in any of claims 1 to 15, wherein the gates are operated electro-mechanically.

18. An engine as claimed in claim 17, wherein solenoids are provided to operate the gates, the armatures of which are drivingly connected to the gates and the actuation of the solenoids is controlled from the rotation of the rotor.

19. An engine as claimed in claim 17 or claim 18, wherein means are provided to hold the gates in their first positions irrespective of the rotation or the rotor.

20. An engine as claimed in any of the preceding claims, wherein means are provided positively to lock each gate in its second position when it has been moved there.

21. An internal combustion rotary engine substantially as hereinbefore described, with reference to and as illustrated in Figures 1 to 4H, or in Figure 5, or in Figure 6, or in Figures 7 to 9, of the accompanying drawings.

22. A method of operating an internal combustion engine as claimed in any of claims 1 to 7, comprising moving the trailing gate, having regard to the sense of rotation of the rotor, to its second position immediately after the ported one lobe passes thereover so as to close off the chamber behind the one lobe to induce a charge in the expanding volume defined thereby, and so as to close off the chamber in front of the other lobe to compress a previously induced charge in the combustion cell and the reducing volume defined between the other lobe and the trailing gate, moving the trailing gate to its first position as the other lobe approaches the trailing gate, igniting the charge in the combustion cell as the other lobe passes thereover, moving the leading gate to the second position immediately after the other lobe has passed thereover to close off the chamber behind the other lobe so as to define an expanding volume as the rotor is driven round by the burning charge and to close off the chamber in front of the one lobe so as to define a reducing volume from which is driven burnt gas resulting from combustion of a previously induced charge.

23. A method of operating a rotary engine according to claim 9, in which the operation of the gates is controlled so that the combustion chamber being employed on any particular combustion stroke is the chamber next to the one used on the preceding stroke but in the sense opposed to the sense of rotation of the rotor.

24. A method of operating an internal combustion rotary engine substantially as hereinbefore described with reference to Figures 4A to 4H, or to any of Figures 5A to 5F, of the accompanying drawings.