Patent Application
20090315270
THIS INVENTION relates to a seal arrangement, and particularly to a seal arrangement for an internal combustion engine, and to a method of sealing.
According to a first aspect of the invention, there is provided an internal combustion engine which includes a reciprocating member which is arranged for reciprocal motion in a complementary cylinder having parallel and opposed side walls and an arcuate end wall extending transversely between them, the reciprocating member having opposite side edges, with an end edge which extends transversely between them, the side and end edges of the reciprocating member being spaced with respective clearance gaps from the side walls and the end wall of the cylinder, to permit sliding movement of the edges relative to the respective walls upon displacement of the reciprocating member in use, and a sealing arrangement which includes:
elongated side and end sealing elements extending respectively along each of the side and end edges of the reciprocating member; and
respective urging means in engagement with the sealing elements to urge the sealing elements away from the respective reciprocating member edges and into contact with the respective cylinder walls, to bridge the clearance gaps and seal off a combustion chamber which is defined by the cylinder and the reciprocating member.
Part of each sealing element may be positioned in a complementary groove defined in the associated edge of the reciprocating member. Each sealing element may have a T-shaped cross-sectional profile, a base or stem portion of the sealing element being located within the groove and a head portion of the sealing element projecting outwardly and laterally from the groove.
The urging means may be in the form of a plurality of longitudinally spaced helical compression springs which are arranged to act between the sealing elements and the reciprocating member in a direction away from the reciprocating member. In such a case, each groove may include a plurality of longitudinally spaced bores which extend into the vane transversely to that edge, to accommodate the helical springs. In another embodiment, the bias means may be in the form of an elongated leaf spring positioned in each groove between the vane and the respective sealing element.
Ends of the sealing elements may define interconnecting formations which interconnect the ends of the end sealing element with adjacent ends of the side sealing elements. The interconnecting formations may be in the form of sliding dovetail-type formations.
The reciprocating member may have a small thickness dimension relative to its length and width dimensions, so that the reciprocating member may be in the form of a vane or plate. It will be appreciated that the thickness dimension extends circumferentially relative to the vane, the width dimension extending axially and the length dimension extending radially. In such case, the vane may have a pair of opposite major faces connected by the side and end edge faces.
The sealing elements may be of metal, preferably being of cast iron.
An engine as claimed in any one of the preceding claims which includes:
a hub from which the reciprocating member protrudes; and
an engine block within which the hub is mounted, the sealing arrangement including an annular groove or recess in one of the hub and the engine block and an annular seal element positioned in the recess and sealingly engaging the other of the engine block and the hub.
The other of the engine block and the hub may define an annular recess into which the annular seal extends. The annular seal seals against a radial surface of the annular recess in the other of the engine block and the hub. The annular seal may be housed, in use, in an intermediate annular mounting member which is receivable in the annular groove.
The invention will now be further described, by way of example, with reference to the accompanying diagrammatic drawings.
In the drawings:
Referring to
The engine block 12 defines two compartments or cylinders 24, 26, and a central cylindrical cavity 28. The cylinders 24, 26 are diametrically opposed about the cylindrical cavity 28. Each cylinder 24, 26 is arcuate or generally sector-shaped in top plan view, and is rectangular in side elevation. Each cylinder 24, 26 thus has a constant height, while it increases in cross-sectional width radially outwardly from the cylindrical cavity 28 towards the end walls 14, 16. The walls 14, 16, 18, 20, 22, 23 define around their periphery a series of threaded bores 25 for receiving attachment means, such as screws, bolts and/or nuts (not shown) to fasten the walls 14, 16, 18, 20, 22, 23 to one another.
An output member, or reciprocating member, generally indicated by reference numeral 30, comprises a right-circular cylindrical hub 32 and pistons in the form of two co-planar, diametrically opposed, radially outwardly projecting vanes 34, 36. The vanes 34, 36 are relatively thin in relation to their length and height, and are thus plate-like. The vanes 34, 36 act as pistons within the cylinders 24, 26 of the engine 11, being arranged for displacement in the cylinders 24, 26 in response to the combustion of fuel in the respective cylinders 24, 26.
The cylindrical cavity 28 is complementary to the hub 32 and is thus shaped and dimensioned to receive the hub 32 snugly with a peripheral working clearance, such that the hub 32 is held captive in the cylindrical cavity 28 but is pivotally or angularly displaceable about a prime pivot axis 30.1 which is co-axial with the polar axis of the cylindrical cavity 28. The vanes 34, 36 are rectangular when seen in axial section (see
An annular boss 33 projects co-axially from each axial end face of the hub 32, the boss 33 being formed by two halves provided by the respective halves of the hub 32, each boss 33 standing proud of the hub 32 and being receivable in a matched mounting aperture 38 in the top wall 22 and the bottom wall 23 respectively. The output member 30 is thus mounted in the engine assembly 10 such that it is pivotable about pivot axis 30.1. An arcuate displacement of the cylinders 24, 26, measured as an angle with the pivot axis 30.1 being the vertex, is 32°. In other words, each cylinder 24, 26 can be described by movement of the respective vane 34, 36 through 32° about the pivot axis 30.1.
An output shaft 40 (only partially shown in
The engine block 12 defines a set of intake valves 42 and exhaust valves 44 on either side of each cylinder 24, 26. The intake and exhaust valves 42, 44 cooperate with associated intake ports 46, 48 and outlet ports (not shown) defined by the respective side walls 18, 20. As can best be seen in
Two worm gears 50 are keyed to the output shaft 40, one on either side of the engine block 12. Each worm gear 50 meshes with two diametrically opposed gears 52 which are keyed to respective cam shafts 54. The cam shafts 54 are rotatably mounted between two operatively upright cam blocks 56 which are mounted to each side of the engine block 12. A cam 58 is fast with each end of the cam shaft 54 axially inwardly of the cam block 56. The cams 58 (of which there are eight in total, one for each valve 42, 44) drive rocker arms 59 (only one of which is shown) which extend through matched grooves in the cam block 56 and which actuate the valves 42, 44. The cams 58 on the upper cam shafts 54 actuate the intake valves 42 and the cams 58 on the lower cam shafts 54 actuate the exhaust valves 44. The cams 58 at opposed ends of the same cam shaft 54 are not aligned, thereby giving the intake valves 42 at opposite ends of each side of the engine 11 different timing.
Edge faces (i.e. the top, bottom, and end edge faces) of the vanes 34, 36 each define therein an elongated groove 100 extending along that edge to accommodate a seal 102. Each seal 102 is elongated and of cast iron having a T-shaped cross-sectional profile. In an alternative embodiment (not shown), the seal 102 could be a strip having a rectangular cross sectional profile. Each groove 100 has a plurality of longitudinally spaced blind bores 104 which extend normally to the respective edge, to accommodate helical compression springs 106 for urging the seals 102 away from the vane 34, 36 and into contact with the associated wall 14, 16, 22, 23 of the engine block 12. In other embodiments (not shown) each seal 102 is biased by means of a single elongated leaf spring.
Axially outer end faces of the hub 32 each define therein a circumferentially extending annular groove or recess 108 to accommodate an annular seal 109. The grooves 108 define therein a plurality circumferentially spaced axially extending blind bores 104 to accommodate helical compression springs 106 for urging the seals 109 away from the hub 32 into contact with the top wall 22 and the bottom wall 23 respectively.
An alternative embodiment of the seal arrangements is shown in
Further, adjacent seals 202 interconnect by means of sliding dovetail-type connections. Top and bottom seals 202 each have a male dovetail connection 204 at their outer ends, while the side seals 202 each have female dovetail connections 206 at both of their ends. In use, when the seals 202 are positioned with their base 202.1 extending within the groove 100, the complementary male dovetail connections 204 and female dovetail connections 206 interconnect, thereby to form a tighter seal at corners of the vanes 34, 36.
The mounting member 212 is secured in the groove 108 of the axially outer face of the hub 32 by a positive connection arrangement including a plurality of bolts or screws 216. The mounting member 212 defines therein a plurality of circumferentially spaced bores 215 which align with respective threaded sockets 217 defined in the groove 108 of the hub 32. Thus, the bolts or screws 216 are received within the bores 215 and are screwingly engaged with the threaded sockets 217 thereby to secure the mounting member 212 to the hub 32. The bolts or screws 216 are counter-sunk such that their respective head portions lie below an axially outer face of the mounting member 212.
Referring now also to
The seals 102, 109, 112 (and 204, 210) are of cast iron or may, instead, be of another suitable material.
A trochoidal oil pump 60 (only partially shown) includes an outer ring gear having eleven radially inwardly projecting rounded teeth, the outer ring gear being fast with the engine block 12. An inner ring gear, or conjugate gear, has ten radially outwardly projecting rounded teeth, and a plurality of radially inwardly projecting teeth. The inwardly projecting teeth of the inner ring gear mesh at a single point with teeth on the output shaft 40, the inner ring gear therefore being driven by the output shaft 40. The inner ring gear follows an epicycloidal path about the output shaft 40, and a hypocycloidal path within the outer ring gear. As the curved teeth of the inner ring gear mesh consecutively with the curved teeth of the outer ring gear, oil is forced between the respective curved teeth and forced into guided oil paths to lubricate the hub 32 and other moving parts. The engine block 12 defines therein a plurality of oil guide paths, some of which can be seen in the form of bores 61.
Referring now to
The hub 32 is hollow, and a cam housing 74 is mounted inside the hub 32. The cam housing 74 is fast with the hub 32 for movement with the hub about the pivot axis 30.1. However, the cam housing 74 is pivotally mounted on the hub 32, via journal bearings 76, to pivot about a cam axis 74.1 which is normal to the pivot axis 30.1. The cam axis 74.1 intersects both the output shaft 40 and the pivot axis 30.1. The cam housing 74 is therefore able to pivot relative to the engine block 12 about two orthogonal axes: the pivot axis 30.1 with the output member 30; and the cam axis 74.1 relative to the output member 30.
The cam axis 74.1 is also transverse to the rotational axis 40.1. In this example, the rotational axis 40:1 is normal to the pivot axis 30.1. It will be appreciated that, in other embodiments of the invention, the pivot axis 30.1 and the rotational axis 40.1 can be co-axial.
The output shaft 40 has fixed thereto a disc 80 which is inclined relative to the rotational axis 40.1 (further described below).
The output shaft 40 passes through a passage 82 defined in the cam housing 74. For Illustrative purposes,
The cam housing 74 defines two inwardly directed axially spaced or side walls 86 within the passage 82. One of the side walls 86 is provided by an axially inner surface of the locking ring 92. The side walls 86 are arranged to bear against the thrust bearings 90, so that, when assembled, the disc 80 is sandwiched between the thrust bearings 90 which are, in turn, sandwiched between the opposed and parallel side walls 86. The side walls 86, thrust bearings 90, and disc 80 thus, in use, are forced to remain in a parallel face-to-face spatial relationship, co-axial with the wobble axis 80.1.
The side walls 86 bear against the inclined disc 80 via the thrust bearings 90, the side walls 86 therefore in use acting as cam members or cam faces and the inclined disc 80 as a cam follower, with frictionless, or low-friction, sliding movement of the disc 80 relative to the side walls 86 being permitted by action of the thrust bearings 90.
In use, and referring now to
A fuel-air mixture, fed through the intake port 56 via the intake valve 42, is compressed in a first combustion chamber 34.1. A spark plug (not shown) sparks in the combustion chamber 34.1 igniting the fuel-air mixture in conventional fashion. The fuel-air mixture expands, displacing the vane 34 in a direction indicated by arrow 35.1, and hence causes the output member 30 to pivot about pivot axis 30.1.
The cam housing 74 moves with the output member 30 about the pivot axis 30.1 due to its pivotal connection to the output member 30, as described above. The cam faces 86 of the cam housing 74 bear against the inclined disc 80 (the cam follower) via the thrust bearings 90. When the vane 34 is at one extremity of its stroke (referred to further as top dead centre, for ease of description), as shown in
It is to be appreciated that engagement of the cam housing 74 with the disc 80 is such that the orientation of the cam housing 74 must follow that of the disc 80. Because the output shaft 40 is journalled in the engine block 12, movement of the cam housing 74 and the disc 80 is linked to rotation of the output shaft 40, their orientation remaining perpendicular to the wobble axis 80.1. Upon rotation of the output shaft 40, either due to forces transferred to it from the output member 30 or due to the shaft's momentum, the wobble axis 80.1 is rotated about the rotational axis 40.1. As the wobble axis 80.1 intersects the rotational axis 40.1 at the centre of the cam housing 74, the wobble axis 80.1 describes a conical path co-axial with the rotational axis 40.1 and having its vertex at the centre of the cam housing 74.
The output member 30, when propelled by combustion in the chamber 34.1, thus exerts a moment on the cam housing 74 about pivot axis 30.1. It will be appreciated that forces between the cam housing 74 and the disc 80 are perpendicular to the interacting faces, thus being parallel to the wobble axis 801. For ease of explanation, these forces can be represented by a pair of forces which act on diametrically opposite parts of the periphery of the disc 80, the forces acting in opposite directions and being parallel to the wobble axis 80.1. Each of these forces can be reduced to component forces in three orthogonal axes. For ease of description, the two axes which are visible in
It will be appreciated that only the z-component of the cam forces will create a moment about the rotational axis 40.1, and that the remaining forces will either result in pivoting of the cam housing 74 about the cam axis 74.1 or be counteracted by the shaft bearings.
When the output member 30 is thus at top dead center (
As the engine 11 moves into an orientation shown in
At the same time, an air-fuel mixture already present in combustion chamber 36.1 is being compressed by the vane 36 moving in a direction indicated by arrow 37.1. As the output shaft 40 rotates, it drives the worm gears 50, which mesh with the gears 52 to rotate the cams 58 about the cam shafts 54. One cam 58 displaces the rocker arm 59 associated with the intake valve 58 of combustion chamber 36.2, and displacement of the vane 36 in the direction of the arrow 37.1 therefore draws fuel-air mixture into the chamber 36.2.
Chamber 34.2 contains exhaust gas, and a rocker arm 59 opens the exhaust valve 44 associated with chamber 34.2, and the displacement of the vane 34 in the direction of the arrow 35.1 exhausts the exhaust gas from the chamber 34.2.
As the ignited fuel-air mixture in the chamber 34.1 continues to expand, the output member 30 is displaced further, into the orientation shown in
At bottom dead centre, no net moment is again exerted on the output shaft 40, but the output shaft 40 rotates past the bottom dead centre because of its angular momentum. At bottom dead centre, the output member 30 changes the direction of its movement about the pivot axis 30.1, because of the momentum of the output shaft 40 and/or a flywheel connected to it.
The fuel-air mixture in chamber 36.1 is now compressed, and the above described process is repeated, with the fuel-air mixture in chamber 36.1 being ignited.
Although the output member 30 moves from bottom dead centre to top dead centre in a direction opposite to its movement from top dead centre to bottom dead centre, the output shaft 40 is rotated in the same direction by the output member 30 via the converting arrangement. This is due to the inclined disc 80 having an opposite inclination relative to the output shaft 40 when viewed in the y-z plane. The cam forces are thus exerted on opposite sides of the disc 80 relative the cam forces during opposite movement, the resultant couple or moment transferred to the output shaft 40 being of similar magnitude and orientation to that transferred during opposite pivotal movement of the output member 30.
Although a chamber firing order of 34.1→36.1→36.2→34.2 is described, the engine 11 may have any convenient firing order, based on the timing of the valves 42, 44 and firing of the spark plugs.
As the output shaft 40 rotates, it drives the inner ring gear of the trochoidal oil pump 60 thereby distributing oil throughout the engine block 12.
In other embodiments of the invention, the disc 80 can be replaced by a seat or collar on which one or more thrust bearings are mounted for cam engagement with the cam housing 74.
The Inventor believes that the invention as exemplified has a number of advantages. The engine is relatively compact, and therefore has a high power to weight ratio. Furthermore, the pivotally reciprocating vane configuration provides two combustion chambers per cylinder, thereby increasing the power output of the engine.
Importantly, the conversion mechanism is operable to convert effectively the pivotally reciprocating motion of the output member into rotational motion of the output shaft. The conversion mechanism is relatively compact, being housed within the hub of the output member.
Also, the engine may use as fuel either petrol by adjusting the compression ratio to about 10:1, or diesel by adjusting the compression ratio to about 20:1. The configuration of the combustions chambers further allows the engine to be configured for either two-stroke mode or four-stroke operation.
Further, the Inventor believes that the engine is well-suited for use of hydrogen as fuel and by virtue of its configuration will be more stable when using hydrogen than a conventional piston engine.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB07/50096 | 1/12/2007 | WO | 00 | 7/17/2008 |
