GB2304818A - I.c. engine with reciprocating pistons in rotary radial cylinders - Google Patents

Abstract

The engine has an outer casing 2, supported on a base 12, and an inner cylinder casing 3 with radial bores in which pistons 4 reciprocate. The connecting rods 5 of the pistons 4 drive respective crank wheels 6 which mesh together so that the timing can be easily set and adjusted. A shaft 7 projects centrally from each crank wheel 6 and each shaft 7 is located in a bore (24) of an output shaft (23,fig.3). An ignition point 8, inlet port 9, and exhaust port 10 are provided in the outer casing 2. Resilient seals (29) in the form of sprung plates (30,figs.7,8) are provided at the outer ends of the cylinders and open and close automatically as casing 3 rotates inside casing 2. In a modification (fig.4), the crank wheels 6 do not mesh together but the output shafts 7 each have a splined portion (19) which form part of a planetary output gear set. Any number of cylinders, including one, may be used.

Description

INTERNAL COMBUSTION ENGINE The present invention relates to internal combustion engines.

Such engines are well known and generally work to either a two or a four stroke principle.

In this regard, the term 'stroke' refers to different operational stages of the engine, namely in a four stroke engine, an induction stroke, a compression stroke, a power stroke and an exhaust stroke.

A common principle of such engines is that the reciprocating action of a piston within a cylinder is converted via a connecting rod and a crank shaft arrangement into rotational movement of the crank shaft. In conventional engines, a number of cylinders are generally provided, each of which is fixed in position relative to the engine block, the power of the engine being taken as rotational movement of the crank shaft.

In a four stroke engine, the power is developed only during one stroke. Thus a single cylinder four stroke engine has a low degree of uniformity whereby rotation of the crank shaft is subject to considerable accelerations and decelerations during a cycle. For more smooth and uniformed running, multicylinder engines are provided, in which the operation of the various cylinders is staggered so that the various cylinders do not develop the power stroke simultaneously but successively. By increasing the number of cylinders, the smoothness and uniformity of the engine is increased, but also disadvantageously there is an increase in the engine size and weight and its complexity, involving complicated crank shaft and connecting rod arrangements.A further problem arises in that by increasing the number of cylinders, achieving and maintaining accurate timing of the engine is made more difficult.

In two stroke engines, a complicated arrangement of fans or vacuum chamber arrangements is necessary so that the four operations of induction, compression, power and exhaust are incorporated into two strokes of the piston and cylinder. The provision of fans and/or vacuum arrangements adds to costs and often such engines require high maintenance by virtue of the sealing criteria required for correct operation thereof.

There is also known a rotary piston engine (Wankel) wherein a piston having a generally triangular shape with convex sides rotates within a cylinder housing having a generally oval shape and which is slightly constricted in its middle. The edges of the rotating piston open and close ports in the cylinder walls so that the piston itself controls the breathing of the engine without the aid of valves. The three enclosed spaces formed between the piston and the cylinder walls successively increase and decrease in size as the piston rotates. These variations in the spaces are used for drawing in the fuel and air mixture, for compressing the mixture, for combustion and discharging the burned gases.

The benefit of the rotating piston is that there are no oscillating masses which have to be alternately accelerated and retarded, as occurs in a conventional piston engine.

Consequently, the forces of inertia associated with such oscillatory motion are obviated. As a result, higher speeds of rotation are possible. However, the rotation piston engine has inherent problems in relation to the sealing of the three chambers in relation to one another. Intercommunication between these chambers is detrimental to the proper functioning of the engine. Moreover, the outputs of the engine in relation to its size is compromised by the particular triangular arrangement of the rotating piston.

It is thus an object of the present invention to provide an engine arrangement which seeks to alleviate the problems of the prior art.

According to an aspect of the present invention there is provided an internal combustion engine comprising an engine housing having a bore; a cylinder casing housed in the bore; at least one cylinder/piston combination extending substantially radially within the bore; and crank means disposed within the cylinder casing and associated with the at least one piston; wherein the cylinder casing is rotatably housed within said bore.

With such an arrangement a powerful and compact engine can be provided.

Preferably, the crank means comprises at least two splined/toothed crank wheels, each associated with a respective piston, the crank wheels being arranged to engage each other. In this way, the timing of the engine can be accurately set and easily maintained.

In preferred embodiments, the splined/toothed crank wheels are arranged to engage a splined/toothed annulus which is fixed relative to the engine housing. The splined/toothed crank wheels can thus rotate as planetary wheels within the annulus.

Conveniently, the crank means further comprise a axially projecting shaft member.

Preferably, each shaft member is coupled to an output shaft so as to harness drive from the engine.

Preferably the cylinder casing houses four piston/cylinder combinations disposed regularly about a longitudinal axis of the cylinder casing. Such an arrangement provides a smooth running and compact engine.

In certain preferred embodiments, each shaft member cooperates with a splined/toothed annulus provided on a cover plate. In such embodiments, each shaft member may include a splined/toothed portion for cooperation with the toothed or splined annulus. Each shaft member may extend beyond the splined/toothed portion so as to be received in a bore of an output shaft. With such an arrangement, rotational movement of each crank means about its own axis can be translated into rotational movement of the output shaft about its axis.

Preferably, each cylinder has a seal at its outer periphery.

The seals may comprise a generally arcuate base plate member and side spring plate members which are resiliently urged away from the base member.

Conveniently, the annulus and splined/toothed crank means are arranged so that reciprocating motion of each piston is coordinated with induction, compression, power and exhaust stroke areas of the engine housing.

In preferred embodiments, the cylinder casing is mounted for sliding contact with an internal surface of the engine housing.

Preferably, the internal surface of the engine casing includes at least one elliptical or non-circular portion. Such portions can assist in the functioning of the seals and can aid the efficiency of the strokes of the engine.

Certain embodiments of the invention will now be described by way of example and with reference to the drawings; in which: Figure 1 shows a cross-sectional view through an engine of a first embodiment of the present invention; Figure 2 shows an inside view of a cover plate of the first embodiment; Figure 3 shows a part cross-sectional view of the engine of Figures 1 and 2; Figure 4 shows a cross-sectional view through an engine of a second embodiment of the present invention; Figure 5 shows an inside view of a cover plate of the second embodiment; Figure 6 shows an exploded view of the engine of Figures 4 and 5; Figures 7 and 8 show side and plan views of a first seal for use with the present invention, and Figures 9 and 10 show plan and side views respectively of a second seal type for use with the present invention.

Figure 1 shows in cross-sectional view an engine block 1 of the present invention. The engine block includes an outer casing .2 in which is rotatably mounted a cylinder casing 3.

The outer casing is supported on base 12. The generally cylindrical cylinder casing houses four pistons 4 which are arranged to reciprocate radially in bores 4' therewithin. A connecting rod 5 connects each piston with a crank wheel 6.

The crank wheels 6 are splined or toothed and are arranged so that the teeth on adjacent crank wheels mesh. Thus, rotation of one wheel results in rotation of all the wheels, such that each piston moves in a predetermined manner within the cylinder casing in relation to the other pistons.

In this way, the timing of the four piston/cylinder combinations can be easily set and adjusted. The fixed nature of the timing of each piston/cylinder combination in relation to each of the other combinations enhances the reliability of the engine.

A shaft 7 projects centrally from each crank wheel 6. As shown in Figures 2 and 3, shafts 7 sit in a central aperture 11 in a cover plate 15 so that each shaft is located in a corresponding bore 24 of an output shaft 23. The shafts 7 can rotate within their respective bores 24, and may be mounted on bearings (not shown) for this purpose. The output shaft itself can rotate freely in relation to the coverplate by way of a bearing member 22, which may be an annular needle bearing. The cover plate includes a splined/toothed annulus 14 which is fixed in relation to the engine block by way of webs 17 and mountings 18. In use, with the engine assembled, the annulus engages teeth on the crank wheels 6.

As shown in Figure 1, an ignition point 8, in the form of a spark plug or the like is provided in the outer casing as are inlet and exhaust ports 9 and 10 respectively. At the end of each piston/cylinder combination, there is provided a seal or gasket 29, as shown particularly in Figures 7 and 8, such seals comprising sprung plates 30 urged resiliently upwards from a base plate member 31. The seals 29 sit neatly at the end of each piston cylinder combination and open and close automatically on rotation of the cylinder casing 3 in the engine block housing.

Operation of the engine is as follows. Reference 9 on Figure 1 shows an air/fuel inlet in the engine outer casing. On rotation of the cylinder casing 3 past the area of the inlet, the piston of each piston/cylinder combination is drawn radially inwardly by way of movement of the crank wheel 6 and connecting rod 5. Thus an air/fuel mixture is drawn into each cylinder as it passes the inlet. This induction stroke area of the engine outer casing is designated A. As the cylinder casing rotates further in a clockwise direction, the piston 4 reaches its most radially inward position and then is forced radially outwardly thus compressing the air/fuel mixture within the cylinder. This compression stroke area of the engine is designated B.

Compression continues until the piston reaches its most radially outward position at C where ignition is performed.

The force generated by ignition of the compressed air/fuel mixture drives the piston radially inwardly and thus causes rotation of the crank wheel corresponding to that piston.

In this embodiment, since each crank wheel 6 is coupled to the other crank wheels by virtue of their respective splined/toothed meshing, the timing of the four strokes of the engine can be accurately set up and maintained.

As a result of the rotation of the crank wheels with respect to the toothed annulus 14, the shafts 7 rotate about a longitudinal axis of the cylinder casing 3. This rotation is translated by way of the output shaft 23 into rotation thereof.

In the power stroke area, identified as D.on Figures 1, the piston is urged inwardly until it reaches its most radially inward position. The exhaust gases are subsequently discharged through port 10 during the exhaust stroke area identified by E, where the piston is moved outwardly under the action of crank wheel 6 and connection rod 5. In this manner a cycle of the engine is completed.

A further embodiment is shown in Figures 4 to 6. In this embodiment, the cover plate 15', as shown in Figure 5, includes an annulus 14' which together with a free rotating sun wheel arrangement 16 forms a ring 21 which is arranged to receive shafts 7'. Annulus 14' is fixed against rotating relative to the engine block by way of webs 17 and mountings 18.

As shown in Figures 4, 5 and 6, the shafts 7' each include a splined or toothed portion 19 and a plain cylindrical end portion 20. The shafts 7' are arranged to pass through ring 21 such that the plain end portions 20 project outside the cover plate 15 and the cogged or splined portions engage and inters it with the splines provided on the annulus 14' and the sun wheel 16.

Rotation of each shaft 7' about its own axis results in the shafts themselves rotating around the ring 21, about an axis thereof. As the shafts rotate about the ring axis, the cylinder casing 3 itself is rotated about the ring axis. The sun wheel 16 is seated on a bearing member 22 which may comprise a needle bearing or the like, thus presenting low friction to the splined/toothed shafts 7' moving around the ring 21. The shafts 7' each extend past the cover plate 15 to cooperate with output shaft 23. In this respect, the output shaft comprises a stepped cylinder having four bores 24 to receive the ends of shafts 7'. Rotation of the shafts 7' about the axis of ring 21 causes rotation of the output shaft about its axis. Drive can thereafter be taken from the output shaft 20 by any suitable means.

Rotation of the crank wheels about their own axes is therefore translated via the cover plate arrangement into rotation of output shaft 23.

In both embodiments, by suitable arrangement of numbers and distribution of splines/teeth on, for example the shafts 7', crank wheels 6 and annulus wheels 14, 14', the reciprocating motion of the pistons 4 can be made to correspond correctly with the angular position of the cylinder casing relative to the induction, compression, power and exhaust stroke areas of the outer casing.

Furthermore, the output of the output shaft 23 can be varied and geared as desired by altering relative teeth numbers and diameters of the splined/toothed components of the engine.

The smoothness and power of the engine can be varied by altering the number of the piston/cylinder combinations within the cylinder casing. In the embodiments shown, having four piston cylinder combinations, with one rotation of the engine cylinder casing, each of the four piston/cylinder combinations goes through a full stroke cycle, namely an induction stroke, a compression stroke, a power stroke and an exhaust stroke.

Although, not shown in the Figures, the arcuate surfaces of the cylinder casing 3 and the outer casing 2 of the engine which are in sliding contact may be configured to be slightly non-circular so as to assist in the different strokes of the engines and to aid the sealing function of seals 29. The surfaces may in this respect be elliptical to provide a lead in area for the seals or to, for example, enhance the compression stroke of the engine.

Figures 9 and 10 show a secondary form of seal adapted to replace the seal shown in Figures 7 and 8 with a lower friction alternative.

The arrangement of Figures 9 and 10 is adapted for location at the same position as those shown in Figures 7 and 8 with the exception that it allows the possibility of the seal moving along a predetermined annular track preferably in the outer casing 2. Figure 9 thus shows a two part seal for location over a piston bore 4' having a rectilinear bore, but may be readily adapted to configure with a circular bore.

In the sealing arrangement 40 of Figures 9 and 10 a generally U-shaped sealing member 41 is formed with a circumferentially extending sealing piece 42 with inwardly extending legs 43.

Similarly the sealing member 44 is provided with legs 45, the terminal ends of which are normally in abutment with the ends of lugs 43. The seal cooperates in dn appropriate track 46 in the outer casing 2 and is retained about the outer end of the bore 4'.

Further each circumferentially extending sealing piece 42 is provided with a roller bearing 47 which is adapted to roll in contact with the sides of the track 46.

In one embodiment the seal 40 acts simply to seal the outer casing 2 against the outer circumference of the cylinder casing 3. In this case the track 46 is of a plain annular form and the seal 40 moves in conjunction with the bore 4' such that compression is maintained appropriately.

In another embodiment however the track may be generally annular, but may be offset over portions to a degree, as shown in Figure 9, so that an optional shutter feature 47 may be brought into play to obturate at least part of a sealed portion in use.

The track 46 may be of various forms, for example it may be adapted for cooperation with roller bearings which operate radially in pairs rather the circumferentially as single elements. This decreases friction while increasing the complexity of the outer casing in manufacture.

In all these latter cases the ignition point 8 is preferably displaced from the radial position shown in Figures 1 and 4 and placed so as to fire laterally into the top of the cylinder bore 4' for ease of construction.

It will be understood that the engine components may be made from any suitable materials, such as metals, metal alloys, ceramics, plastics etc. Conventional cooling systems may be incorporated into the engine as desired.

It will be understood that the embodiment illustrated shows an application of the invention in one form only for the purposes of illustration. In practice, the invention may be applied to many different configurations. The detailed embodiments being straight forward for those skilled in the art to implement.

For example, rather than four piston cylinder combinations, any number from one upwards may be used as required with slight modification of the output shaft.

Claims (10)

CLAIMS:

1. An internal combustion engine comprising: an engine housing having a bore; a cylinder casing housed in said bore, at least one cylinder/piston combination extending substantially radially within the bore, and crank means disposed within the cylinder casing and associated with at least one piston; characterized in that the cylinder casing is rotatably housed within said bore.

2. An engine according to claim 1, wherein the crank means comprises at least two splined/tooth crank wheels, each associated with a respective piston, the crank wheels being arranged to engage each other.

3. An engine according to either of claims 1 or 2, wherein the splined/tooth crank wheels are arranged to engage a splined/tooth annulus fixed relative to the engine housing thereby to allow the crank wheels to rotate as planetary wheels within the annulus.

4. An engine according to any preceding claim, wherein the crank means further comprises an axially projecting shaft member.

5. An engine according to any preceding claim, wherein the cylinder casing houses four piston/cylinder combinations disposed regularly about a longtitudal axis of the cylinder housing.

6. An engine according to any preceding claim, wherein each shaft member cooperates with a splined/toothed annulus provided on a cover plate whereby rotational movement of each crank means about its own axis is translated into rotational movement of an output shaft about its axis.

7. An engine according to any preceding claim, wherein each cylinder comprises a seal at its radially outer periphery.

An engine according to claim 7, wherein each seal comprises a generally arcuate base plate member and sidespring plate members resiliently urged away from the base member.

9. An engine according to claim 7, wherein the seal is a two-part seal provided with roller bearings to retain the seal operatively in situ relative to the cylinder, and wherein the seal cooperates with a track on the circumferential surface of the outer housing.

10. An engine substantially as hereinbefore set forth with reference to, and/or as illustrated in, any one of Figures 1 to 10.