A VARIABLE VOLUME DEVICE AND SYSTEM THEREFOR

Abstract: A rotary device having at least one variable volume cavity (16); the volume of said cavity (16) varying cyclically during operation of said device; said variable volume cavity (16) comprised of an unswept volume portion (17); the volume of said unswept portion (17) remaining at a predetermined constant volume during each cycle of operation of said device; said variable volume cavity further including a swept volume portion (18); the volume of said swept volume portion (18) varying cyclically from zero volume to a predetermined maximum volume during each cycle of operation of said device; said device including first independent set point means (19) to set the volume of said unswept volume portion (17); said device including second independent set point means (20) to set said predetermined maximum volume of swept volume portion (18).

Description: A VARIABLE VOLUME DEVICE AND SYSTEM THEREFOR The present invention relates to variable volume devices and systems therefor and, more particularly, such devices which form the basis, although not exclusively so, for engines and compressors. BACKGROUND Various kinds of devices and mechanisms are known including various kinds of engines and compressors which incorporate variable volume cavities. The most common of these is perhaps a cylinder and piston assembly wherein the piston reciprocates within the cylinder thereby defining an internal cavity whose volume varies approximately cyclically in accordance with the cyclic movement of the piston. When used as the basis for an internal combustion engine such variable volume cavity has drawbacks when implemented in its simplest form. Accordingly, most modern engines include additional apparatus to modify the characteristics of the cavity and the condition of the contents of the cavity. Such apparatus can include scavenging systems, superchargers and the like. Superchargers, themselves, can include a variable volume cavity as the basis for compression of gases for infusion into and modification of the gases and conditions within the variable volume cavity of an internal combustion engine. Again, the supercharger and its variable volume cavity in its rudimentary form may not have the most suitable characteristics . In particular, taking a super charger or like compressor device as an example there is typically little adjustment possible with such devices and certainly little if any adjustment possible "on the run" when the device is m use m association with an internal combustion engine or like device within a car or like vehicle. More specifically such variable volume devices have not had a control system associated with them and have not been amenable to the use of a control system m association with them. It is an object of the present invention to address one or more of the abovementioned disadvantages or at least provide a useful choice. In particular forms variable volume devices have been known m the form of "slant axis machines". See, for example, the disclosure of International Patent Application WO87/04495, the disclosure of which application is incorporated herein by cross-reference. This form of device is from a class of rotary devices which is to say devices whose components operate by a rotating motion or rotating relative motion as to be contrasted with the reciprocating motion of, for example, a piston within a cylinder. These slant axis devices are known to have certain advantages. However, heretofore, even these devices have suffered from the same disadvantages mentioned above including insufficient ability to control the parameters of such devices when in use. It is a further object of the present invention to address or ameliorate one or more of the abovementioned disadvantages, particularly but not exclusively, insofar as they relate to slant axis devices. BRIEF DESCRIPTION OF INVENTION Accordingly, in one broad form of the invention there is provided an engine system comprising an engine having at least one variable volume cavity for combustion of a fuel; said engine further having means for moveable sealing said cavity so as to define a containment volume for retaining said fuel during combustion of said fuel within said containment volume thereby to convert at least some energy released by said combustion to mechanical movement of working portions of said engine; said engine system further comprising fluid urging means for urging an oxidation fluid into engagement with said fuel within said containment volume . Preferably said means for moveably sealing comprises a piston. Preferably said working portions include said piston. Preferably said means for moveably sealing comprises a rotor . Preferably said working portions include said rotor. Preferably said means for moveably sealing comprises a first partial disk member of a slant axis device. Preferably said working portions include said first partial disk member. Preferably said fluid urging means comprises a compressor system. Preferably said compressor system comprises a rotary device . Preferably said rotary device includes a variable volume cavity having an unswept portion and a swept portion therein; said rotary device further including first independent set point means for adjusting said unswept portion and second independent set point means for adjusting said swept portion. Preferably said compressor system is driven directly from said working portions. Preferably said compressor system is driven by a motive source independent of said working portions. Preferably said compressor system is driven by an electric motor. In an alternative broad form of the invention there is provided a compressor system having at least one variable volume cavity; said compressor further having means for moveably sealing said cavity so as to define a containment volume for compression of a fluid within said containment volume . Preferably said variable volume cavity includes an unswept portion and a swept portion. Preferably said system further includes first independent set point means for adjusting the volume of said unswept portion. Preferably said system further includes second independent set point means for adjusting the volume of said swept portion. In yet a further broad form of the invention there is provided a rotary device having at least one variable volume cavity; the volume of said cavity varying cyclically during operation of said device; said variable volume cavity comprised of an unswept volume portion; the volume of said unswept volume portion remaining at a predetermined constant volume during each cycle of operation of said device; said variable volume cavity further including a swept volume portion; the volume of said swept volume portion varying cyclically from zero volume to a predetermined maximum volume during each cycle of operation of said device; said device including first independent set point means to set the volume of said unswept volume portion; said device including second independent set point means to set said predetermined maximum volume of said swept volume portion. Preferably said device includes linkage means between said first independent set point means and said second independent set point means . Preferably said linkage means includes a slot guide. In yet a further broad form of the invention there is provided a rotary device including at least one variable volume cavity therein. Preferably said at least one variable volume cavity includes an unswept portion and a swept portion. Preferably the volume of said unswept portion can be varied by first independent set point means. Preferably the volume of said swept portion can be varied by second independent set point means . Preferably said rotary device comprises a slant axis device . Preferably said device comprises a modified slant axis device; said modified slant axis device comprising a housing; a vane plate within said housing rotatable about a vane rotation axis; at least one partial disk member rotatable within said housing about a partial disk member rotation axis; said at least one partial disk member defining a variable working volume between at least portions of said vane plate, said partial disk plate and said housing; said working volume varying cyclically during operation of said rotary device. Preferably said working volume varies cyclically in accordance with the angle of offset between said vane rotation axis and said partial disk member rotation axis. In yet a further broad form of the invention there is provided an assembly comprising at least a first variable volume device in fluid communication with a second variable volume device. Preferably said at least first variable volume device includes a cavity having a swept portion and an unswept portion. BRIEF DESCRIPTION OF DRAWINGS Embodiments of the present invention will now be described with reference to the accompanying drawings wherein: Fig. 1 is a time series diagram of a variable volume cavity; Fig. 2 is a block diagram of a first variable volume cavity in accordance with a first embodiment of the invention in communication with a second variable volume cavity; Fig. 3.1 is a schematic diagram of components of a slant axis device in accordance with an embodiment of the present invention; Fig. 3.2 comprises views of a vane of the slant axis device of Fig. 3.1; Fig. 3.3 comprises views of another component of the device of Fig. 3.1; Fig. 3.4 comprises views of another component of the device of Fig. 3.1; Fig. 3.5 comprises views of the housing of the device of Fig . 3.1; Fig. 3.6 comprises views of a further component of the device of Fig. 3.1; Fig. 3.7 comprises views of part of the gymbal assembly of the device of Fig. 3.1; Fig. 3.8 comprises views of a further part of the gymbal assembly of the device of Fig. 3.1; Fig. 3.9 comprises views of a further component of the gymbal assembly of the device of Fig. 3.1; Fig. 3.10 comprises a perspective view of the slant axis device of Fig. 3.1; Fig 4.1 comprises a view of a modified slant axis device according to a second embodiment of the invention as illustrated in Fig. 4.5; Fig. 4.2 illustrates the arrangement of further components of the modified slant axis device of Fig. 4.5; Fig. 4.3 illustrates relative positioning of two partial disk members of the modified slant axis device of Fig. 4.5; Fig. 4.4 is a side section view of the partial disk members of Fig. 4.3; Fig. 4.5 is a perspective view of a modified slant axis device according to a second embodiment of the present invention; Fig. 5.1 is a perspective view of a modified slant axis device according to a third preferred embodiment of the present invention; Fig. 5.2 is a side section view of the modified slant axis device of Fig. 5.1; Fig. 5.3 is an end section view of the modified slant axis device of Fig. 5.1; Fig. 5.4 is a further perspective view of the slant axis device of Fig. 5.1; Fig. 5.5 is a further perspective view of the slant axis device of Fig. 5.1; Fig. 5.6 is a detailed perspective view of the slant axis device of Fig. 5.1; Fig. 5.7 is a perspective view, partially assembled, of the device of Fig. 5.1; Fig. 5.8 is a perspective view, assembled, of the device of Fig. 5.1; Fig. 5.9 is a further perspective view of the device of Fig. 5.1; Fig. 5.10 is a further perspective view of the device of Fig. 5.1; Fig. 5.11 is a further perspective view of the device of Fig. 5.1; Fig. 5.12 is a cutaway view of the slant axis control mechanism in an offset position; Fig. 5.13 is a perspective view of the mechanism of Fig. 5.1 in an offset position; Fig. 5.14 is an end view of the arrangement of Fig. 5.12 ; Fig. 5.15 is a perspective view of a position of a partial disk member at a near-zero unswept volume position; Fig. 5.16 is a top plan view of the assembly of Fig. 5.15; Fig. 5.17 is a partial assembly of the arrangement of Fig. 5.1; Fig. 5.18 is a perspective view of the mechanism in an offset position; Fig. 5.19 is a further perspective view of the mechanism in an offset position; Fig. 5.20 is a further perspective view of the housing of the arrangement of Fig . 5.1; Fig. 6.1 is a side, cut away view of a variable volume device having an adjustable unswept volume portion for use in association with the control arrangement of Fig. 6.2; Fig. 6.2 illustrates a control arrangement for use in association with the variable volume device of Fig. 6.1; Fig. 7.1 is a perspective view of an exemplary interconnected pair of variable volume devices for use in association with the engine of a motor vehicle or like device . DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS With reference to Figs. 1 and 2 certain basic concepts common to all the preferred embodiments of the present invention will be described before moving onto a description of exemplary embodiments of the invention. Fig. 1 is a time series diagram of a variable volume device 10 in this instance in the form of a cylinder 11 inside which reciprocates piston 12. The time series diagram progresses from Fig. 1A through to Fig. ID wherein the piston moves from top dead center in Fig. 1A to bottom dead center in Fig. IB back to top dead center in Fig. 1C and back to bottom dead center in Fig. ID. At top dead center in Figs. 1A and 1C the piston 12 and cylinder 11 together define a volume comprising unswept portion 13 of variable volume device 10. The difference in volume between the top dead center position in Fig. 1A and the bottom dead center in Fig. IB defines a swept portion 14 of the variable volume device 10. The term "swept" is used in this instance to allude to the fact that the piston slides or sweeps through this portion of the variable volume device 10. The maximum internal volume position defined by the bottom dead center position in Fig. IB and ID defines a variable volume cavity 15. It will be observed, in use and during progressing from Fig. 1A through to ID that the piston 12 operates cyclically causing the volume of the variable volume cavity 15 to vary cyclically correspondingly. The concept of a swept portion and an unswept portion of a variable volume cavity can be applied equally to other variable volume devices including those which operate by relative rotating motion as opposed to reciprocating motion. Specific embodiments of this concept will be described later with particular reference to a modified slant axis device. The slant axis device is a member of a class of machines which can be broadly described as rotary devices in that the working components within the device rotate rather than reciprocate . With reference to Fig. 2 a first variable volume cavity 16 is illustrated in diagrammatic form and comprises a first unswept volume 17 and a first swept volume 18. Also illustrated diagrammatically is first independent set point means 19 being means adapted to set a specific predetermined value to the volume comprising the first unswept volume 17. Similarly and correspondingly second independent set point means 20 comprises means to adjust the volume of first swept volume 18. It is to be understood that the adjustment contemplated to be carried out by the set point means 19, 20 is not a cyclic adjustment as occurs during cycling of the variable volume cavity but a set point adjustment to the volume comprising the unswept volume 16 as previously defined and - li ¬ the swept volume 18, also as previously defined with reference to Fig. 1. Where the first variable volume cavity 16 is utilized as a compressor it can be made to output a charge of air or like fluid which has been compressed by the volume of swept volume 18 for input into a second variable volume cavity 21. The second variable volume cavity 21 can itself include a second unswept volume 22 and a second swept volume 23. The cavity could form part of either an engine or a compressor or other device. In the specific embodiments to be described further in this specification the second variable volume cavity can form part of an engine and wherein the first variable volume cavity 16 is specifically interconnected with second variable volume cavity 21 so as to produce an interconnected variable volume device 24. Fig. 7.1 provides a specific but merely exemplary, example of an application in the automotive field wherein the first variable volume cavity forms part of a super charger or like compressor device adapted to selectively and controllably pressurize variable volume cavities in the form of cylinder cavities within an internal combustion engine via its inlet manifold. It is particularly desirable in embodiments which follow that first independent set point means 19 is, indeed, independent of second independent set point means 20 whereby it is possible, in at least selected ones of the embodiments which follow, to entirely independently adjust, for example, first unswept volume 17 entirely independently of adjustment to first swept volume 18 within the one first variable volume cavity 16. This independence opens up particular control opportunities not available in variable volume devices which do not have such independence of control . In the detailed description of preferred embodiments which now follows there are given descriptions of particular forms of modified slant axis devices which provide one particular way of providing a variable volume cavity and, more particularly, a variable volume cavity having independent set point means for its unswept volume and its swept volume. Also described m exemplary embodiments are interconnected variable volume devices where the modified slant axis device can be applied with particular advantage. MODIFIED SLANT AXIS DEVICE - FIRST EMBODIMENT A rotary machine m the form of a modified slant axis device 25 with particular reference to Figs. 3 is described and including the characteristic of having the ability to make independent adjustment of both the unswept volume and swept volumes of its variable volume cavity. With reference to Fig. 3.1 which is a schematic drawing the present invention provides for a member 101 of at least partial disk shape which is rotatable upon a diametric axis 102. There is also provided at least one partial disk member 103 rotateable about axis 104 and also pivotable about a diameter of member 101. Axis 104 intersects and divides a diameter of member 101. Means (not shown m the schematic Fig. 3.1) are also provided to vary the angle between axis 102 and axis 104. Means (not shown m the schematic Fig. 3.1) are also provided to vary the angle between a plane of member With operation of the above described mechanism it will be seen that if axis 102 and axis 104 are held m fixed relationship to one another then with rotation the surface of member 103 will cyclically converge on and diverge from the surface of member 101 and if the angle between axis 102 and axis 104 is increased then the angle of convergence and divergence is increased and vice versa. It will also be seen that if the angle between a plane of member 103 and axis 104 is increased then the surface of member 103 will, with operation, converge closer to the surface of member 101 and vice versa. It will be seen that if such a mechanism is enclosed in, and in sealing relationship to, a spherical or part spherical housing then a displacement mechanism suitable for a pump and many other applications will be created with the benefit that the mechanism will provide for a displacement device or pump having a variable displacement and a variable compression ratio . By way of non limiting example a practical example of a displacement mechanism having both variable displacement and variable compression ratios by utilising the above disclosed mechanism is described below. With reference to Figures 3.2 through 3.10 disk member 101 is constructed in two halves and with a section cut out as illustrated, member 105 is a short steel rod with a hole through it, member 105 is held between the two halves of member 101 so that it can rotate on its axis at the centre of member 101 a rod 105A of greater length than the diameter of member 101 is passed through the hole in member 105 so that it at all times falls on a diameter of member 101 and is pivotable about the axis of member 105. A part spherical housing is constructed in two halves (figure 3.5) with each half having a hole in it as illustrated. Each half of the part spherical housing is bolted to disk member 101. Two essentially half circular members 106 each with a tongue protrusion incorporated as illustrated are pivotably attached to the rod 5A such that each may pivot about the axis of the rod 105A and are therefore pivotable about a diameter of member 101. Upon assemble the tongue protrusion of the two members 106 intrudes into the part spherical housing by passing through the hole in each half of the part spherical housing. Two part disk shaped members 103 are provided and are attached to the tongue protrusion of members 106 so that they are held in position within the part spherical housing and are pivotable about a diameter of member 101. A square guide 107 is provided and mounted inside a bearing such that member 101 and other members may rotate about it. A square shaft 108 is slidably passed through square guide 107. Square shaft 108 has a gymbal mechanism 109 attached to the end protruding into the housing. Pivotably attached to the centre of the gymbal mechanism are two support members 110 which are also pivotably connected to the tongues of members 106 such that if square shaft 108 is slidably moved further into the housing area then members 106 and 103 are caused to pivot about a diameter of member 101 in one direction and if the square shaft 108 is slidably moved towards the outside of the housing then members 106 and 103 pivot in the opposite direction so as to decrease or increase the angle between the members 106 respectively and consequently also members 103. Square guide 107 is also provided with a pivot point 111 so that the gymbal and therefore the angle between axis 102 and 104 may be altered by pivoting the square shaft 108 about pivot point 111. In operation the entire assembly with the exception of square guide 107 and square shaft 108 rotate. In operation square shaft 108 is held stationary excepting that the movement in and out and about pivot point 111 is provided so as to enable variation of both displacement and compression ratio during operation. For clarity members 110 and also mounting means and bearings are omitted from the partially assembly view Fig 3.10. There are several means of porting the mechanism. MODIFIED SLANT AXIS DEVICE - SECOND EMBODIMENT A rotary machine in the form of a modified slant axis device 26 with particular reference to Figs. 4 is described and including the characteristic of having the ability to make independent adjustment of both the unswept volume and swept volumes of its variable volume cavity. The purpose of this second embodiment is to provide a slant axis mechanism 26 which provides for: - a) means to reverse the flow of the working fluid without changing the direction of operation of the mechanism or the valving or porting b) means to mount or support all rotating parts on relatively small and high speed bearings c) means where both torque and reactive torque are manifest at a shaft and no torque (other than friction generated) is present or manifest at the housing or body of the mechanism, and: a) means to vary the displacement of the mechanism b) means to vary the compression ratio of the mechanism. The fact that no torque or reactive torque is present or manifest at the housing or main body of the mechanism creates a new class of mechanism namely a slant axis mechanism where neither torque nor reactive torque is manifest at the main body of the mechanism which in this instance is the spherical housing in Fig 4.5. The present invention in its basic configuration not providing for either variable displacement or variable compression consists of a hollow spherical housing 201 having a bearing housing 202 and a further bearing housing 203. A vane member 204 which is a circular plate with a partial wedge portion cut from it. A part conical member 205 which is rigidly fixed to vane member 204. A concave spherical section 206 which has a hole in the centre of it and which is rigidly connected to part conical member 205. Shaft 207 is connected to vane member 4 such that its extended axis passes through the centre of the hole in 206. The assembly comprising members 204, 205, 206, and 207 are rotatably located within the spherical chamber of housing 201 by locating shaft 207 within housing 202 and the bearing housing 203 inserted into the hole in the concave spherical section 206. There is also provided two members 208 each being a partial spherical wedge or segment truncated near the apex and being joined together by connecting means 209. There is also provided two rods 210 having a part circular section and having a length near equal to the diameter of vane member 204. Each rod 210 is connected to each other by a pin passing through a hole in the centre of vane member 204 so that they are free to rotate on the face of vane 204. There is also provided a further member 211 of concave spherical section which is rigidly connected to shaft 212. A "T" section slot (not shown) is machined into the inner surface of member lithe said slot traversing the centre of the inner surface of member 211. Member 213 is a bearing housing which is located at one end within the slot machined in member 211 such that it can slide within the said slot. Member 215 is a shaft rotatably located within bearing housing 213. Support members 214 rigidly connect members 208 to member 215. Two ports (not shown) are cut into the surface of the spherical housing to allow the flow of working fluid to and from the two working chambers defined by the above described mechanism. With reference to Fig. 4.5 one of the said ports would be located directly out from the page and extend from the point marked "A" to the point marked "B" and would have a width such that in the position drawn the port would be covered by the edge or perimeter of vane 204. The second port would be 180 degrees opposite and of similar dimension. With the above described mechanism if the housing 201, shaft 212 and bearing housing 213 were held in a fixed position then with rotation of shaft 207 the vane 204 would rotate about the axis of shaft 207 and members 208 would rotate about the axis of shaft 215 so causing the two chambers defined by the mechanism to vary in volume causing a flow of air through the ports cut into the spherical chamber walls. It can be seen from the above mechanism that if bearing housing 215 was moved from its illustrated position to the other side of the concave spherical section 211 then the angle at which the members 208 are held in relation to vane member 204 would change accordingly and with continued operation of the assembly the direction of flow of air through the ports would be reversed. Such a change in position of housing 215 could be accomplished by either one of two methods. Either shaft 212 and member 211 could be rotated through 180 degrees relative to vane 204 or alternatively bearing housing 215 could be moved along the slot cut into the inner surface of member 211 until it was a similar distance from the axis of vane 204 and then be again held fixed in the new position. Similarly it can be seen that if bearing housing 215 is moved within the slot to any intermediate position then the angle between the two axis will change with the result that the displacement of the mechanism will change. It can also be seen that if the angle between the faces of the two members 208 is altered then the compression ratio of the mechanism will be changed. By way of non limiting example means to change the displacement during operation can be provided by means of a hydraulic ram being connected to bearing housing 215 and to a point on the perimeter of concave spherical section 211 with the hydraulic line passing through shaft 212 to hydraulic controlling means so as to facilitate the movement of bearing housing 15 along the slot cut into member 211 as described above. By way of non limiting example means may be provided to change the compression ratio during operation by providing a series of interlocking fingers in place of connecting means 209 so as to facilitate the rotation of each member 208 in relation to each other and also by providing pin connecting means at each end of each support member 214 and by providing hydraulic means to raise and lower shaft 215 within bearing housing 213 and a hydraulic line passing through shaft 212 to hydraulic controlling means. For simplicity and ease of illustration seals have not been drawn or described Fig. 4.1 is a section of the members described. Fig. 4.2 is a side section of Fig 4.1 with the addition of rod members 210. Fig. 4.3 is plan of members 208 and 209. Fig. 4.4 is a side section of Fig 4.3. Fig. 4.5 is a section of assembled mechanism with one chamber at maximum volume and one chamber at minimum volume . MODIFIED SLANT AXIS DEVICE - THIRD EMBODIMENT With reference to Figs. 5 there is illustrated a modified slant axis device 27 according to a third embodiment of the present invention which, as compared with the arrangements of the first and second embodiments previously described exhibits one or more of the following features in comparison: Is a shorter device for the same volume of air output; Enables better sealing of the partial disk members; Reduces change in inertia during operation; Is more easily balanced thereby allowing higher speed of rotation. The overall manner of operation of the device of the third embodiment is similar in principle to the manner of operation of the modified slant axis devices of the first and second embodiments to the extent that the arrangement is such that at least one partial disk member 28 rotates within housing 29 about a partial disk member rotation axis 30, in the instance of Fig. 5.2 inclined at an angle alpha with respect to vane rotation axis 31. Vane 32, in this instance, is interconnected with housing 29 and together they rotate about axis 31, in use. Provided angle alpha is greater than zero the arrangement is such that, in use, as vane 32 rotates about vane rotation axis 31 and partial disk member 28 rotates about partial disk member rotation axis 30 a working face 33 of partial disk member 28 is caused to cyclically converge on and diverge from corresponding working face 34 of vane 32 which, together with corresponding inner wall 35 of housing 29 define a variable volume 36. As perhaps best seen in Fig. 5.3, as partial disk member 28 rotates about its axis 30 its vane contact edge 37 oscillates about center 38 of vane 32 from oscillation axis BB through oscillation axis AA and onto oscillation axis CC and back again in the course of one cycle. The angle beta representing the extent of oscillation is related to axis offset angle alpha. The degree to which working face 33 approaches working face 34 m one cycle is governed by the angular setting of working face 33 with respect to axis 30. This angle gamma is set by rotation of control arm 39 about pivot 40 which is achieved by rotational urging of gear 41. Adjustment of angle gamma is achieved by corresponding raising or lowering of control bar 42 which, via gear block 43 causes corresponding rotation of gears 41 and hence corresponding movement of control arm 39 and, ultimately, variation m angle gamma. Adjustment of angle gamma is, m effect, an adjustment of the amount of unswept volume within variable volume 36 m any given cycle of operation. Modified slant axis device 27 also allows variation of the swept volume portion of variable volume 36 by side to side movement or adjustment of the protruding portion of bar 42 as best seen in Fig. 5.1. Side to side movement of the protruding portion of bar 42 causes a rocking motion of gear block 44 thereby to adjust angle alpha and hence the maximum degree to which partial disk member 28 opens during any one cycle relative to working face 34 of vane 32. It is to be noted that the axis of gear block 44, m this embodiment, always points towards the geometric center of the assembly within housing 29. In addition, m its preferred form the center of pressure within variable volume 36 is aligned with support axis 45 of partial disk member wherein load on pivot axis 40 is minimized. A further characteristic of this preferred embodiment is that the arcuate peripheral edges 46 carry no or minimal load in the axial direction. That is, there is little or no load born by peripheral edges 46 at their point of juxtaposition with the inner wall of housing 29. Porting within the assembly is such that, with particular reference to Fig. 5.8 air or other fluid can be taken in via inlet port 47 and, after passing through variable volume 36 is ejected as a charge from outlet port 48 for feeding, for example, into an inlet manifold such as that illustrated in Fig. 7.1 of a car petrol engine. Fig. 5.12 is a cutaway view of the slant axis control mechanism in an offset position. Fig. 5.13 is a perspective view of the mechanism of Fig. 5.1 in an offset position. Fig. 5.14 is an end view of the arrangement of Fig. 5.12. Fig. 5.15 is a perspective view of a position of a partial disk member at a near- zero unswept volume position. Fig. 5.16 is a top plan view of the assembly of Fig. 5.15. Fig. 5.17 is a partial assembly of the arrangement of Fig. 5.1. Fig. 5.18 is a perspective view of the mechanism in an offset position. Fig. 5.19 is a further perspective view of the mechanism in an offset position. Fig. 5.20 is a further perspective view of the housing of the arrangement of Fig. 5.1. As seen, for example, in Fig. 5.13 pin B moves in an arch within slot 54. The arrangement is such as to constrain the movement of control bar 42 whereby the unswept volume defined by partial disk member 28 with respect to vane 32 is close to zero for all swept volume settings. The slot can be profiled in other ways so as to achieve different forms of constraint upon the movement of bar 42 and hence the settings for the swept and unswept volumes. Finally, it will be appreciated that the device 27 incorporates a first and a second partial disk member arranged symmetrically about vane 32. In this instance corresponding symmetrical components are numbered as for the components already described with respect to the first of the partial disk members. INTERCONNECTED VARIABLE VOLUME DEVICE - FIRST EMBODIMENT With reference to Figs. 6.1 and 6.2 and the variable volume devices described with reference to the previous embodiments a particular interconnected arrangement of variable volume devices as illustrated in principle in Fig. 2 is exemplified with reference to an internal combustion engine . The ordinary otto cycle internal combustion engine normally runs over a large range of load and throttle settings and is not normally optimised for any one setting. The purpose of this embodiment is to provide means to optimize such engines over the range of load and throttle settings . Compression ratios in ordinary petrol engines are limited by the octane rating of the fuel employed or commonly employed. This ratio is set so that when the throttle is opened wide at low engine RPM and good volumetric efficiency thereby attained the fuel will not detonate. This is so even though the normal operating conditions of engines is at a low volumetric efficiency for example at high RPM with mid to wide throttle and also at low RPM and low throttle settings. To say that volumetric efficiency is low at low RPM and low throttle settings would appear self evident and necessary to maintain a low power setting and this is quite obviously true however it also means that the engine is running well below the attainable efficiency because the fuel/air charge is introduced at low pressure and is in fact rarified before the compression stroke begins so that while it may be said that the compression ratio is say 10 to 1 the fact is that the charge begins in a much rarified state so that the effective compression ratio is far less than 10 to 1 similarly at high RPM or at any cruise setting with less than a wide open throttle the charge is compressed from a rarified state. The obvious effect of this is that at top dead centre after ignition the cyclinder pressure is in fact well below what can be safely achieved. The net result is that at almost all throttle and load settings the mean effective pressure of a stroke is below what could be obtained with a commensurate reduction in efficiency. Clearly if one starts with a rarified charge the compression ratio possible before detonation becomes a problem is greater and if one increases the compression ratio to as high a level as possible commensurate with avoiding detonation then for any given fuel/air charge the mean effective pressure of a stroke will be increased and it naturally follows that the overall efficiency of the engine will increase. The purpose of this first preferred embodiment of an interconnected variable volume device is to provide an engine with a variable compression ratio and which ratio is a function of inlet air flow and engine RPM or in other words for any given engine RPM the compression ratio of the engine is increased as inlet air flow decreases and vice versa. With such an arrangement with the use of a supercharger the air flow could be made to exceed the volumetric displacement of the pistons at any given RPM in which case using the same rule the compression ratio of the cylinders would be decreased but the cylinders charged with a fuel air mixture at elevated pressure with the effect that a small engine could under load conditions output more power than would otherwise be possible. Under these conditions the fuel efficiency would be reduced however the power to weight ratio of the engine would be increased and as most engines used in automobiles spend the greatest part of their life under partial load conditions the net gain in fuel and overall efficiency would outweigh the fuel efficiency losses at high load conditions. The present invention provides for metering means for inlet air flow and or a supercharge of variable capacity so as to deliver a known volume of air and also means to measure the RPM of an engine at all times and means to calculate the inlet air flow as a proportion or ratio of the piston displacement together with means to proportionately vary the compression ratio of the engine so as to achieve as near as practical to the maximum compression ratio commensurate with avoiding detonation for any particular inlet air flow / engine RPM. By way of non limiting example Fig 6.1 shows a means of varying the compression ratio of an engine 301. The main bearing is situated in a block 302 which is located within grooves so as to enable the block 302 to be raised or lowered in relation to the cylinder head. Screw means 303 are provided so as to enable the block 302 to be raised or lowered as desired and a lever 304 is provided to turn the screw. In practice a servo mechanism (not shown) can move the lever 304. Fig 6.2 provides a schematic diagram of the invention where "A" is air flow measuring means and "B" is an RPM measuring means which incorporates an electronic calculator to calculate the air flow as a proportion or ratio of the piston displacement rate at the time of sample. If the air flow is less than the displacement rate of the pistons the calculator sends a signal to open a valve m hydraulic reservoir "D" so as to move hydraulic servo "C" in such a direction as to increase the compression ratio of the engine and vice versa. By way of further amplification of the concept of this first embodiment of interconnected variable volume devices described thus far m an internal combustion engine work is obtained by expanding the products of combustion within an expansion chamber and the amount of available energy is limited by the extent to which the products of combustion expand while doing work against a piston. In the early part of the nineteenth century Sadi Carnot recognised that m order to obtain a reasonably sized and reasonably efficient internal combustion engine it would be necessary to compress the working gas before combustion. This fundamental truth is now seen to be self evident and is universally accepted. Notwithstanding this fundamental truth and despite the invention of many means to gain increased efficiency from internal combustion engines almost none of the internal combustion engines m common usage today are optimised insofar as compression before combustion is concerned. Where an internal combustion engine is required to operate under a variety of engine speed and engine load conditions it is desirable to have a variable compression and expansion ratios or more correctly variable swept volume/clearance volume ratio, the reasons why this is so are well known and derive from the fact that at partial throttle settings and at engine speeds where volumetric efficiency drops off the effective compression ratio is reduced in that the reduced charge is compressed to a less than optimum pressure with the result that efficiency is reduced. Over the years there have been many inventions which have been designed and intended to address this problem. Some representative examples are as follows: 1. US Patent 5165368 discloses a complex means for varying the piston stroke in response to torsional impulses on the crankshaft which vary with load. The text of the specifications also refers to various other inventions of similar intent. 2. US Patent 5329893 discloses a means of varying clearance volume by raising and lowering the cylinder block by electric motor in response to variation in inlet manifold pressure which is claimed or stated to be a measure of engine load. US Patent 5562069 discloses a similar invention actuated by hydraulic means however it does not disclose the circumstances or triggering means for varying the compression ratio. 3. US Patent 5605120 discloses a rotatable eccentric crankshaft bearing which is claimed to be adjustable during the operation of the engine but the specification does not provide for actuating or trigger circumstances or mechanism so as to relate the compression ratio to mass of the working charge. The specification states the obvious fact that the supply of air and fuel to the engine would need to be adjusted concurrently with the alteration to compression ratio but provides no means whatsoever to do the same. 4. Us Patent 4174683 discloses an engine having variable inlet cam timing and also variable compression ratio where the inlet valve open period is reduced concurrently, proportionately and synchronously with an increase in compression ratio and vice versa and controlled by accelerator pedal position. What is obvious with such a mechanism is that the mass of charge driven by atmospheric pressure and introduced to the cylinders is a function of both engine speed and inlet valve timing and not inlet valve timing alone as disclosed in the specifications with the result that the variation in compression ratio in the circumstances disclosed results in the compression ratio having no relationship whatsoever to the mass of the charge actually inducted. 5. US Patent 5255637 discloses a schematic for an engine having a variable compression ratio mechanism and variable valve timing together with a turbocharger that does not have a waste gate. It is proposed to vary both the compression ratio and the valve timing in response to various engine sensors including a knock sensor, a speed sensor and an intake manifold pressure or boost sensor. 6. US Patent 4958 discloses an extremely complex means of varying the effective compression ratio in a fixed geometry turbocharged or supercharged engine by varying the valve timing and boost pressure in response to various engine condition sensors and actuated by computer. Optimum fuel efficiency of an internal combustion engine occurs when the combustion chamber is filled with the coolest possible charge, free of residual exhaust gases and where combustion is complete and maximum pressure obtained concurrent with the piston reaching top dead centre and where the said maximum pressures reached is the maximum that is commensurate with avoiding detonation, followed by as high an expansion ratio as is mechanically possible. This condition is obtained by complete scavenging, followed by the introduction of a cool charge mass which is balanced to the mechanical compression ratio of the engine and ignition occurring at a point related to engine speed to ensure complete combustion before expansion begins. These facts remain true at any engine speed and/or load condition. For any given engine geometry mechanical efficiency or power to weight ratio of an engine may be obtained at the expense of fuel efficiency by providing a larger mass of charge and a lowered mechanical compression ratio and expansion ratio which results in a greater mean affective pressure and higher exhaust pressures and temperatures. Whether fuel efficiency or mechanical efficiency is required then in either case the highest possible pressure at top dead centre is desireable . Each of the many schemes for improving engine performance by balancing or matching charge mass to variable engine compression and expansion ratios or vice versa disclosed to date including the representative samples referred to above remain compromises that do not achieve the desired result . In most instances prior art seeks to sense engine conditions and to then adjust the various mechanisms to the existing parameters. In other words they first detect a load condition or detonation and then seek to adjust the mechanics after the triggering event or condition exists, often this adjustment then results in an alteration of the triggering event or condition so that further alteration would then becomes necessary. Some other disclosures are seriously deficient m that while they provide means to vary either or both of valve timing and compression/expansion ratios they do not provide means to relate the variation to the then current charge mass or any other engine condition. Other disclosures particularly US Patent 4174683 vary both valve timing and compression ratios together with the intended purpose of adjusting the charge mass by varying the valve timing, the problem with this approach is that the charge introduced or aspirated will vary with engine speed and load so that once again these is no relationship between the mass of the charge and the compression ratio set. In summary for various reasons all of the prior art fails to properly balance or relate the charge mass to the compression ratio and in some instances there is no attempt to do so disclosed. In addition many of the disclosures to date in addition to having the abovementioned shortcomings are extremely complex. The present embodiment seeks to provide simple and effective means to continuously balance the charge mass and the compression ratio of an internal combustion engine under all operating conditions The present embodiment provides for a positive displacement type internal combustion engine commonly represented by the reciprocating piston type engine where the geometry may be altered m use so as to provide a variable swept volume/unswept volume ratio, the said swept volume/unswept volume ratio being hereinafter referred to as "compression ratio" . The present invention also provides for at least one positive displacement air pump which has a displacement volume or swept volume which may be altered or varied m use. The said pump is disposed so as to be driven by the said engine at a speed constantly proportionate to the said engine speed. The mechanism for altering or varying the displacement volume of the air pump is linked either mechanically or by means of servo mechanisms to the mechanism for altering or varying the compression ratio of the said engine such that the displacement of the said air pump and the compression ratio of the said engine are inversely varied or in other words as the displacement of the air pump is increased the compression ratio of the engine is decreased and vice versa so as to maintain a constant relationship between the mass of air discharged by the air pump and the compression ratio of the engine such that after compression and combustion the combustion chamber pressure is as high as possible short of the pressure at which detonation may ensue. To put it more succinctly the relationship between the displacement volume of the air pump and the compression ratio of the engine is such that the final pressure within the engine at the top of the compression stroke is constant at all power and engine speed settings. The embodiment also provides that the varying means of the displacement of the air pump and the compression ratio of the engine be variable in use by linkage either directly or by servo motor (s) to an accelerator pedal or similar device so as to facilitate the variation of power levels or settings of the engine . In an alternative preferred arrangement there is provided a turbine driven by exhaust gas which is connected via a drive shaft to a reduction gearbox and then the output from the reduction gearbox be connected to a second drive pulley or other suitable drive means of the variable displacement pump so that a proportion of the otherwise waste energy is in fact returned as shaft or engine output power. A centrifugal or other suitable clutch mechanism may be interposed either between the turbine and gearbox or between the gearbox and variable displacement pump and the turbine and exhaust plumbing to be configured by any of a variety of known means to direct exhaust gas to the turbine once a pre- set exhaust pressure and/or temperature is reached. Fuel may be introduced into the air mass provided by the pump by any of the known means . Without departing from the scope of the invention as disclosed above means may also be provided to adjust the relationship between the displacement volume of the air pump and the compression ratio of the engine so that fuels of various octane ratings may be used from time to time. Such means would reduce the compression ratio in relation to charge mass for fuels having a lower octane rating and vice versa. In addition means may also be provided to vary the relationship between the displacement of the air pump and the compression ratio of the engine such that with a change in density altitude the displacement volume of the air pump is proportionately changed so that it will deliver a constant mass for each related engine compression ratio position. Without departing from the scope of this embodiment two or more pumps may be used and where two or more are used one or more may be utilized to provide scavenging air through a second inlet manifold system where the separate manifold may communicate with a separate inlet valve which is timed and intended to introduce scavenging air only or alternatively opening and closing means may be provided on the first and second manifolds so as to first communicate scavenging air and then communicate the main mass of air and fuel to the inlet valve port. In such a circumstance the second air pump providing the scavenging air would have its volume variable so as to provide a constant relationship to the varying clearance volume or unswept volume of the engine while the first air pump would have its volume proportionately reduced so that the total mass provided by both pumps would provide the mass of charge appropriate to the power setting plus any proportion which may be lost to the scavenging process. Without departing from the scope of this embodiment where two or more variable volume air pumps are used a first pump may provide through appropriate manifold and valving means a lean mixture during the first part of an induction stroke while a second pump may provide a richer mixture during a second part of the induction stroke or m such other manner as may provide a stratified charge and where such means are used each pump would be proportionately altered m volume so that both pumps together provide the mass of charge appropriate to any power setting. Alternatively where three pumps are used the first may provide scavenging air while the second and third pumps provide charges of different richness as set out above. Alternatively a first pump may provide a charge having fuel of one octane rating during the first part of the induction stroke while a second pump may provide a charge containing a fuel of a lower octane rating during the second part of the induction stroke or m such other manner as may provide a stratified charge such that the fuel of lesser octane rating is burned before the combustion chamber pressures have reached the detonation pressure for that particular fuel . While the scope of the present embodiment provides for the use of a variable volume positive displacement pump of any construction and also provides for the use of any of the known variable compression ratio engines it is obvious that for any variable volume pump to be practical and efficient it must also provide for a variable swept volume/unswept volume ratio such that at all times the unswept or clearance volume should be as close to zero as practicable. In addition to be practical and efficient any such pump should also be light in weight of simple and reliable construction. In a preferred embodiment of this embodiment the pump disclosed in the third preferred embodiment of a modified slant axis is utilized. It will be understood that the variable displacement pump may be run at any constant relative speed to the said engine and the maximum displacement varied appropriately. In other words if a pump were run at twice the speed of an alternative pump then the pump could have a maximum displacement of half the alternative pump. In a preferred embodiment the compression ratio of the engine can be variable between a low of about eight to one to a high of whatever ratio is commensurate with obtaining the highest compression pressure of the mass of charge required to run the engine at idle speed on the highest octane fuel which is intended to be used with the engine and the volume of the variable volume pump should be variable between a volume which provides a charge to the engine low enough to maintain an idle speed in the abovementioned conditions and a volume which will provide an adequate mass to the engine which after compression when the engine is set to its lowest compression ratio will be compressed to the highest possible pressure short of the pressure at which detonation will occur when combustion occurs . It will be readily understood that the present embodiment obviates the need to have variable valve timing and excepting in the circumstances set out above where two or more pumps provide charge proportions having different properties or application the need for other complex and expensive arrangements such as multiple inlet valves is reduced. The reason for this is that the engine will under all conditions of operation be provided with a charge mass appropriate to the required power setting and where a separate pump is utilized to provide scavenging air the scavenging will be thorough at all engine speeds. This is so because at any power and speed setting the manifold pressure will simply stabilise at the point where the exact mass of charge or volume of scavenging air required to be inducted will be inducted. It will also be understood that the present invention provides physical means to maintain a constant high efficiency without the need for complex electronic engine management systems . In summary the present embodiment provides a variable compression ratio engine of any suitable known type or which may become known together with any suitable variable volume pump or compressor but preferably of the type set out in Figs . 3 or Figs . 5 where the engine and pump are connected firstly via any suitable drive means whether it be belt and pulley, chain and sprocket or direct gearing and secondly connected by any suitable conduit so as to introduce the charge provided by the variable volume pump into the manifold system of the engine. Any suitable mechanical linkage or servo mechanism may be employed to link the operation of the variable volume pump to the varying mechanism of the variable compression ratio engine and each in turn is connected by any suitable linkage or servo mechanism to an accelerator pedal or other power setting lever or device. INTERCONNECTED VARIABLE VOLUME DEVICES - SECOND EMBODIMENT A further example of interconnection of variable volume devices in accordance with the principles of Fig. 2 will now be described again with reference to an internal combustion engine . In an internal combustion engine work is obtained by expanding the products of combustion within an expansion chamber and the amount of available energy is limited by the extent to which the products of combustion expand while doing work against a piston. In the early part of the nineteenth century Sadi Carnot recognised that in order to obtain a reasonably sized and reasonably efficient internal combustion engine it would be necessary to compress the working gas before combustion. This fundamental truth is now seen to be self evident and is universally accepted. Compression is also obviously fundamental to the operation of compression ignition engines. The reason why compression before combustion is so important to efficiency is that increased pressures are present during the power stroke and the expansion ratio of the products of combustion is also increased. Reduced power settings reduce the efficiency of petrol engines. Reduced power settings in a petrol engine are achieved through a reduction in the mass of the fuel air mixture inducted into the engine, in a petrol engine of fixed geometry this result in a lowered effective compression ration with a resultant lowering of efficiencies Engine capacities in automotive and other applications are generally intended to be adequate to meet occasional demand requirements such as hill climbing, overtaking or such other peak load condition as may occur. The use of engines of excess capacity means that in normal usage which is most of the time the engine is running at a lower proportionate power settings with consequent lowered efficiencies than would be the case if a smaller engine could be used. It may be said that if two alternative engines are capable of performing a particular task the engine which performs that task at the higher effective compression ratio will perform the task with the greatest efficiency. While the use of normal supercharging and or turbocharging does enable a smaller engine to perform a greater task than it otherwise could there is a greater loss of efficiency at reduced power settings than would otherwise be the case as supercharging and turbocharging generally necessitate the use of low compression pistons with the result that at reduced power settings the effective compression ratio is reduced even further than is the case in a normally aspirated engine. The purpose of the present embodiment is to provide means to maintain volumetric efficiencies of engines of fixed stroke and clearance volume so as to enable smaller engines to perform occasional demand tasks that would otherwise require either supercharged engines or larger engines so that the said smaller engine when working at reduced power settings operate at a greater effective compression ratio than would otherwise be the case. The present embodiment provides for petrol or similarly fueled internal combustion engine of fixed geometry together with a variable displacement air pump having a minimum displacement of essentially zero displacement and a maximum displacement proportionate to the displacement of the said engine and disposed so as to be driven by the said engine in fixed proportion to the engine speed so that when set at maximum displacement the said air pump delivers to the said engine an air mass which will compress to or near the maximum pressure commensurate with avoiding detonation. The embodiment also provides that the variable displacement mechanism of the variable displacement pump be operated by the accelerator or other power setting mechanism either by direct linkage or by servo. The embodiment provides therefore that the normal throttling means be replaced by the variable displacement pump. It is to be understood that with such an engine and variable displacement pump then as there is no risk of supercharging an engine then such a pump may be used on existing engines without any requirement for the use of low compression pistons or other efficiency reducing modifications. It is also to be understood that the air provided by such a pump could be introduced into the intake manifold system of an engine fifed with electronic fuel injection without modification. It is further to be understood that in an engine having a carburetor the carburetor could be placed on the intake side of the variable displacement air pump or if situated between the air pump and the engine then shrouding or other means may need to be provided so as to maintain a pressure surrounding the carburetor equivalent to that immediately upstream from the carburetor . Without modifying the foregoing, in another embodiment, it is provided that a turbine driven by exhaust gas may be connected via a drive shaft to a reduction gearbox and then the output from the reduction gearbox be connected to a second drive pulley or other suitable drive means of the variable displacement pump so that a proportion of the otherwise waste energy is in fact returned as shaft or engine output power. A centrifugal or other suitable clutch mechanism may be interposed either between the turbine and gearbox or between the gearbox and variable displacement pump and the turbine and exhaust plumbing to be configured by any of a variety of known means to direct exhaust gas to the turbine once a pre-set exhaust pressure and/or temperature is reached. Without departing from the scope of this embodiment as disclosed above, means may also be provided to adjust the relationship between the displacement volume of the air pump and the displacement of the engine so that fuels of various characteristics may be used from time to time. In addition means may also be provided to vary the relationship between the displacement of the air pump and the displacement of the engine such that with a change in density altitude the displacement volume of the air pump is proportionately changed so that it will deliver a constant mass at its maximum displacement setting. Without departing from the scope of the invention two or more pumps may be used and where two or more are used one or more may be utilized to provide scavenging air through a second inlet manifold system where the separate manifold may communicate with a separate inlet valve which is timed and intended to introduce scavenging air only or alternatively opening and closing means may be provided on the first and second manifolds so as to first communicate scavenging air and then communicate the main mass of air and fuel to the inlet valve port. In such a circumstance the second air pump providing the scavenging air would have its volume variable so as to provide a constant relationship to the varying clearance volume or unswept volume of the engine while the first air pump would have its volume proportionately reduced so that the total mass provided by both pumps would provide the mass of charge appropriate to the power setting plus any proportion which may be lost to the scavenging process. While the scope of the present embodiment provides for the use of a variable volume positive displacement pump of any construction it is obvious that for any variable volume pump to be practical and efficient it must also provide for a variable swept volume/unswept volume ratio such that at all times the unswept or clearance volume should be as close to zero as practicable. In addition to be practical and efficient any such pump should also be light in weight of simple and reliable construction. The modified slant axis pump described with reference to Figs. 3, Figs. 4 and Figs. 5 is to be particularly preferred. In a particularly preferred embodiment the pump of Figs. 5 is utilized. It will be understood that the variable displacement pump may be run at any constant relative speed to the said engine and the maximum displacement varied appropriately. In other words if a pump were run at twice the speed of an alternative pump then the pump could have a maximum displacement of half the alternative pump. It will be readily understood by any worker in the field that the present invention obviates the need to have variable valve timing and excepting in the circumstances set out above where two or more pumps provide charge proportions having different properties or application the need for other complex and expensive arrangements such as multiple inlet valves is reduced. The reason for this is that the engine will under all conditions of operation be provided with a charge mass appropriate to the required power setting and where a separate pump is utilized to provide scavenging air the scavenging will be thorough at all engine speeds. This is so because at any power and speed setting the manifold pressure will simply stabilise at the point where the exact mass of charge or volume of scavenging air required to be inducted will be inducted. It will also be understood that the present embodiment provides physical means to maintain a constant high efficiency without the need for complex electronic engine management systems . INTERCONNECTED VARIABLE VOLUME DEVICES - THIRD EMBODIMENT Yet a further example of interconnected variable volume devices will now be described m the context of its application to a diesel engine. In an internal combustion engine work is obtained by expanding the products of combustion within an expansion chamber and the amount of available energy is limited by the extent to which the products of combustion expand while doing work against a piston. In the early part of the nineteenth century Sadi Carnot recognised that in order to obtain a reasonably sized and reasonably efficient internal combustion engine it would be necessary to compress the working gas before combustion. This fundamental truth is now seen to be self evident and is universally accepted. Compression is also obviously fundamental to the operation of compression ignition engines. The reason why compression before combustion is so important to efficiency is that increased pressures are present during the power stroke and the expansion ratio of the products of combustion is also increased. Reduced power settings reduce the efficiency of both petrol and diesel engines. Reduced power settings m a petrol engine are achieved through a reduction m the mass of the fuel air mixture inducted into the engine, m a petrol engine of fixed geometry this result m a lowered effective compression ration with a resultant lowering of efficiencies Reduced power settings m diesel engines are achieved by reducing the volume of fuel injected while maintaining the mass of air inducted. The compression ratio of the inducted air mass is maintained however the products of combustion are diluted by the air mass to the extent that the air mass exceeds the mass required for combustion. Insofar as efficiency is concerned this dilution of the products of combustion is equivalent to a reduction in both compression ratio and expansion ratio and a loss of efficiency occurs. Over the years there have been many inventions which have been designed and intended to address this problem in petrol engines. Some representative examples are as follows: 1. US Patent 5165368 discloses a complex means for varying the piston stroke in response to torsional impulses on the crankshaft which vary with load. The text of the specifications also refers to various other inventions of similar intent. 2. US Patent 5329893 discloses a means of varying clearance volume by raising and lowering the cylinder block by electric motor in response to variation in inlet manifold pressure which is claimed or stated to be a measure of engine load. US Patent 5562069 discloses a similar invention actuated by hydraulic means however it does not disclose the circumstances or triggering means for varying the compression ratio. 3. US Patent 5605120 discloses a rotatable eccentric crankshaft bearing which is claimed to be adjustable during the operation of the engine but the specification does not provide for actuating or trigger circumstances or mechanism so as to relate the compression ratio to mass of the working charge. The specification states the obvious fact that the supply of air and fuel to the engine would need to be adjusted concurrently with the alteration to compression ratio but provides no means whatsoever to do the same. 4. Us Patent 4174683 discloses an engine having variable inlet cam timing and also variable compression ratio where the inlet valve open period is reduced concurrently, proportionately and synchronously with an increase in compression ratio and vice versa and controlled by accelerator pedal position. What is obvious with such a mechanism is that the mass of charge driven by atmospheric pressure and introduced to the cylinders is a function of both engine speed and inlet valve timing and not inlet valve timing alone as disclosed in the specifications with the result that the variation in compression ratio in the circumstances disclosed results in the compression ratio having no relationship whatsoever to the mass of the charge actually inducted. 5. US Patent 5255637 discloses a schematic for an engine having a variable compression ratio mechanism and variable valve timing together with a turbocharger that does not have a waste gate. It is proposed to vary both the compression ratio and the valve timing in response to various engine sensors including a knock sensor, a speed sensor and an intake manifold pressure or boost sensor. 6. US Patent 4958 discloses an extremely complex means of varying the effective compression ratio in a fixed geometry turbocharged or supercharged engine by varying the valve timing and boost pressure in response to various engine condition sensors and actuated by computer . None of the above examples succeed in their intended object as none of them provide means to properly relate the mass of charge to the varying compression ratio of the engines disclosed. Example 1 is interesting in that it seeks, by extraordinarily complex means, to relate compression ratio to torsional forces on the crankshaft. Besides the apparently prohibitive complexity this approach has the obvious shortcoming that it seeks to relate the compression ratio to a condition after that condition exists In other words there is a lag time during which time the triggering condition may well have altered in magnitude. It also appears to me that one charge mass under different load conditions will result in different torsional forces on the crankshaft. The invention therefore fails in its object. Example 2 is based upon the claim that manifold pressure is a measure of engine load, (and therefore charge mass) however this is obviously at best an approximation and once again it is a case of too late in that again the compression ratio is matched to a condition after it exists, in addition there is no means of anticipating the momentary changes or the direction of change. This example also fails because there is no means to continuously relate the charge mass to the compression ratio. Example 3, the specification states the obvious fact that the supply of air and fuel to the engine would need to be adjusted concurrently with the alteration to compression ratio but provides no means whatsoever to do the same. This example also fails. Example 4, the obvious problem with such a mechanism is that the mass of charge driven by atmospheric pressure and introduced to the cylinders is a function of both engine speed and inlet valve timing and not inlet valve timing alone as disclosed m the specifications with the result that the variation in compression ratio m the circumstances disclosed results m the compression ratio having no relationship whatsoever to the mass of the charge actually inducted.. This example also fails. Example 5 also fails for similar reasons. The present embodiment seeks to improve the efficiency of diesel engines by providing means to proportionately vary the clearance volume and inducted air mass m diesel engines so as to maintain high efficiency levels at all power settings . The present embodiment provides for a positive displacement type internal combustion engine commonly represented by the reciprocating piston type engine where the geometry may be altered m use so as to provide a variable swept volume/unswept volume ratio, the said swept volume/unswept volume ratio being hereinafter referred to as "compression ratio" . The present embodiment also provides for at least one positive displacement air pump which has a displacement volume or swept volume which may be altered or varied m use. The said pump is disposed so as to be driven by the said engine at a speed constantly proportionate to the said engine speed. The mechanism for altering or varying the displacement volume of the air pump is linked either mechanically or by means of servo mechanisms to the mechanism for altering or varying the compression ratio of the said engine such that the displacement of the said air pump and the compression ratio of the said engine are inversely varied or m other words as the displacement of the air pump is increased the compression ratio of the engine is decreased and vice versa so as to maintain a constant relationship between the mass of air discharged by the air pump and the compression ratio of the engine such that after compression the combustion chamber pressure is at a pressure typical of diesel engines running at optimum compression. There is also provided a linkage mechanism or servo mechanism which links the operation of the variable displacement pump and the variable compression ratio engine to the fuel injector pump of the engine so as to maintain a constant relationship between all three operating volumes namely fuel volume, inducted air volume and engine clearance volume so as to maintain an optimum relationship between all three throughout the power setting range of the engine. To put it more succinctly the relationship between the displacement volume of the air pump and the compression ratio of the engine and the injected fuel volume is essentially constant at all power and engine speed settings. The embodiment also provides that the varying means of the displacement of the air pump and the compression ratio of the engine and of the fuel injector pump be variable in use by linkage either directly or by servo motor (s) to an accelerator pedal or similar device so as to facilitate the variation of power levels or settings of the engine. Without modifying the foregoing, in another embodiment, not necessarily a preferred embodiment the invention provides that a turbine driven by exhaust gas may be connected via a drive shaft to a reduction gearbox and then the output from the reduction gearbox be connected to a second drive pulley or other suitable drive means of the variable displacement pump so that a proportion of the otherwise waste energy is in fact returned as shaft or engine output power. A centrifugal or other suitable clutch mechanism may be interposed either between the turbine and gearbox or between the gearbox and variable displacement pump and the turbine and exhaust plumbing to be configured by any of a variety of known means to direct exhaust gas to the turbine once a pre-set exhaust pressure and/or temperature is reached. Without departing from the scope of the embodiment as disclosed above means may also be provided to adjust the relationship between the displacement volume of the air pump and the compression ratio of the engine so that fuels of various characteristics may be used from time to time. In addition means may also be provided to vary the relationship between the displacement of the air pump and the compression ratio of the engine such that with a change m density altitude the displacement volume of the air pump is proportionately changed so that it will deliver a constant mass for each related engine compression ratio position. Without departing from the scope of the embodiment two or more pumps may be used and where two or more are used one or more may be utilized to provide scavenging air through a second inlet manifold system where the separate manifold may communicate with a separate inlet valve which is timed and intended to introduce scavenging air only or alternatively opening and closing means may be provided on the first and second manifolds so as to first communicate scavenging air and then communicate the main mass of air and fuel to the inlet valve port. In such a circumstance the second air pump providing the scavenging air would have its volume variable so as to provide a constant relationship to the varying clearance volume or unswept volume of the engine while the first air pump would have its volume proportionately reduced so that the total mass provided by both pumps would provide the mass of charge appropriate to the power setting plus any proportion which may be lost to the scavenging process. While the scope of the present embodiment provides for the use of a variable volume positive displacement pump of any construction and also provides for the use of any of the known variable compression ratio engines as may be adapted to diesel it is obvious that for any variable volume pump to be practical and efficient it must also provide for a variable swept volume/unswept volume ratio such that at all times the unswept or clearance volume should be as close to zero as practicable. In addition to be practical and efficient any such pump should also be light m weight of simple and reliable construction. In a particularly preferred embodiment the pump disclosed m Figs. 5 is utilized. It will be understood by any worker m the field that the variable displacement pump may be run at any constant relative speed to the said engine and the maximum displacement varied appropriately. In other words if a pump were run at twice the speed of an alternative pump then the pump could have a maximum displacement of half the alternative pump. In a preferred form the compression ratio of the engine can be variable between a low commensurate with conventional supercharging to a high of whatever ratio is commensurate with obtaining optimum compression pressure of the mass of charge required to run the engine at the lowest power settings which is intended to be used with the engine and the volume of the variable volume pump should be variable between a volume which provides a charge to the engine low enough to maintain engine operation at low power settings and a volume which will provide an adequate mass to the engine which after compression when the engine is set to its lowest compression ratio will be compressed to pressures commensurate with obtaining high mean effective pressures throughout the power stroke .. It will be understood that the present embodiment obviates the need to have variable valve timing and excepting in the circumstances set out above where two or more pumps provide charge proportions having different properties or application the need for other complex and expensive arrangements such as multiple inlet valves is reduced. The reason for this is that the engine will under all conditions of operation be provided with a charge mass appropriate to the required power setting and where a separate pump is utilized to provide scavenging air the scavenging will be thorough at all engine speeds. This is so because at any power and speed setting the manifold pressure will simply stabilise at the point where the exact mass of charge or volume of scavenging air required to be inducted will be inducted. It will also be understood that the present embodiment provides physical means to maintain a constant high efficiency without the need for complex electronic engine management systems. CONTROL SYSTEM With reference to Fig. 7.1 there is illustrated a first variable volume device 49 comprising, in this instance, the modified slant axis device 27 of the third embodiment wherein its outlet port 48 is caused to inject air charges into inlet manifold 50 of an internal combustion engine (not shown) . The internal combustion engine, with reference to Fig. 2, includes variable volume cavities 21 most often comprising piston in cylinder arrangements such as those illustrated in Fig. 1. In this instance a servo motor 51 operates control bar 42 by means of control signals received from microprocessor based control module 52. The servo motor 51 controls the two degrees of freedom of bar 42 thereby to independently adjust a first independent set point comprising the unswept volume of variable volume 36 and a second independent set point in the form of the maximum value of swept volume in any one cycle of variable volume 36. Vane rotation axis 31 is rotated by electric motor 53 which is powered and speed controlled by control module 52. Control module 52 thus has at its disposal the ability to control three parameters of first variable volume device 49, namely: i. Unswept volume of charge; ii . Swept volume of charge; iii. Speed of rotation of the variable volume 36 and hence the frequency of delivery of air charges. This arrangement hence allows significant control over air charges injected into inlet manifold 50. This degree of control can be used to advantage in conjunction with engine management systems and other sensing arrangements which sense the condition of the engine supplied by the inlet manifold 50 and, more particularly, the condition of the variable volumes 21 therein so as to optimize combustion characteristics within those cavities. The above describes only some embodiments of the present invention and modifications, obvious to those skilled in the art, can be made thereto without departing from the scope and spirit of the present invention.

Claims: CLAIMS 1. An engine system comprising an engine having at least one variable volume cavity for combustion of a fuel; said engine further having means for moveable sealing said cavity so as to define a containment volume for retaining said fuel during combustion of said fuel within said containment volume thereby to convert at least some energy released by said combustion to mechanical movement of working portions of said engine; said engine system further comprising fluid urging means for urging an oxidation fluid into engagement with said fuel within said containment volume. 2. The engine system of Claim 1 wherein said means for moveably sealing comprises a piston. 3. The system of Claim 1 or Claim 2 wherein said working portions include said piston. 4. The engine system of Claim 1 wherein said means for moveably sealing comprises a rotor. 5. The system of Claim 4 wherein said working portions include said rotor. 6. The system of Claim 1 wherein said means for moveably sealing comprises a first partial disk member of a slant axis device. 7. The system of Claim 6 wherein said working portions include said first partial disk member. 8. The system of any one of Claims 1 to 7 wherein said fluid urging means comprises a compressor system. 9. The system of Claim 8 wherein said compressor system comprises a rotary device. 10. The system of Claim 9 wherein said rotary device includes a variable volume cavity having an unswept portion and a swept portion therein; said rotary device further including first independent set point means for adjusting said unswept portion and second independent set point means for adjusting said swept portion. 11. The system of Claim 8 or 9 or 10 wherein said compressor system is driven directly from said working portions. 12. The system of Claim 8 or 9 or 10 wherein said compressor system is driven by a motive source independent of said working portions. 13. The system of Claim 12 wherein said compressor system is driven by an electric motor. 14. A compressor system having at least one variable volume cavity; said compressor further having means for moveably sealing said cavity so as to define a containment volume for compression of a fluid within said containment volume. 15. The compressor system of Claim 14 wherein said variable volume cavity includes an unswept portion and a swept portion. 16. The compressor system of Claim 15 further including first independent set point means for adjusting the volume of said unswept portion. 17. The compressor system of Claim 15 or Claim 16 further including second independent set point means for adjusting the volume of said swept portion. 18. A rotary device having at least one variable volume cavity; the volume of said cavity varying cyclically during operation of said device; said variable volume cavity comprised of an unswept volume portion; the volume of said unswept volume portion remaining at a predetermined constant volume during each cycle of operation of said device; said variable volume cavity further including a swept volume portion; the volume of said swept volume portion varying cyclically from zero volume to a predetermined maximum volume during each cycle of operation of said device; said device including first independent set point means to set the volume of said unswept volume portion; said device including second independent set point means to set said predetermined maximum volume of said swept volume portion. 19. The rotary device of Claim 18 further including linkage means between said first independent set point means and said second independent set point means . 20. The rotary device of Claim 19 wherein said linkage means includes a slot guide . 21. A rotary device including at least one variable volume cavity therein. 22. The rotary device of Claim 21 wherein said at least one variable volume cavity includes an unswept portion and a swept portion. 23. The rotary device of Claim 22 wherein the volume of said unswept portion can be varied by first independent set point means . 24. The rotary device of Claim 22 or Claim 23 wherein the volume of said swept portion can be varied by second independent set point means . 25. The rotary device of any one of Claims 21 to 24 wherein said rotary device comprises a slant axis device. 26. The rotary device of Claim 25 comprising a modified slant axis device; said modified slant axis device comprising a housing; a vane plate within said housing rotatable about a vane rotation axis; at least one partial disk member rotatable within said housing about a partial disk member rotation axis; said at least one partial disk member defining a variable working volume between at least portions of said vane plate, said partial disk plate and said housing; said working volume varying cyclically during operation of said rotary device. 27. The device of Claim 26 wherein said working volume varies cyclically in accordance with the angle of offset between said vane rotation axis and said partial disk member rotation axis. 28. An assembly comprising at least a first variable volume device in fluid communication with a second variable volume device. 29. The assembly of Claim 28 wherein said at least first variable volume device includes a cavity having a swept portion and an unswept portion.

Inventors: THOMPSON GLENN ALEXANDER, THOMPSON, GLENN, ALEXANDER
Applicants: THOMPSON GLENN ALEXANDER, THOMPSON, GLENN, ALEXANDER
Application year: 2000
Main classification: F01C3
IPC codes: F01C3, F01C9, F02B53, F02B55, F04C18