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Title:
MECHANICAL MACHINE AND COUPLING SUITABLE FOR SUCH A MECHANICAL MACHINE.
Document Type and Number:
WIPO Patent Application WO/2016/116836
Kind Code:
A1
Abstract:
Mechanical machine (1) with two or several rotors (8,9) which are each provided with at least one piston (17,18) which can rotate in a toroidal cavity (14) around a central axis (FF'), which cooperate with a machine shaft (3) having a certain angle (Y) in relation to the central axis (FF'), with a mechanical coupling (20), a portion of which is formed by a core (21) having a centre (G) situated on the machine shaft (3) and which coincides with the centre (C) of the toroidal cavity (14), and whereby a uniform rotation of the machine shaft (3) is accompanied by an irregular rotation of the rotors (8,9).

Inventors:
JORISSEN, Mark (Melselestraat 26, 2070 Zwijndrecht, 2070, BE)
JORISSEN, Julien (Tongersesteenweg 203, 3770 Riemst, 3770, BE)
Application Number:
IB2016/050172
Publication Date:
July 28, 2016
Filing Date:
January 14, 2016
Export Citation:
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Assignee:
RESIFID NV (Melselestraat 26, 2070 Zwijndrecht, 2070, BE)
International Classes:
F04C15/00; F01C21/00; F04C29/00
Foreign References:
US20110100321A12011-05-05
FR2391389A11978-12-15
US6461127B12002-10-08
EP2690288A22014-01-29
US20110100321A12011-05-05
Attorney, Agent or Firm:
VAN HUNSEL, Lieven (P.o. Box 34, 2900 Schoten, 2900, BE)
Download PDF:
Claims:
Claims

Mechanical coupling (20) which is suitable for coupling several rotors (8,9) having a common centre

(C) and a common central rotor axis (ΑΑ',ΒΒ') to a machine shaft (3), whereby the central axis (HH' ) of the machine shaft (3) and the common rotor axis

(ΑΑ',ΒΒ') stand at an angle (Y) with respect to one another, whereby the rotors (8,9) can rotate around the common central rotor axis (ΑΑ',ΒΒ') and whereby the rotors (8,9) can also mutually move in relation to one another, characterised in that the coupling

(20) comprises the following elements:

a core (21) which is intended to be firmly connected to or to be part of the machine shaft (3) with a centre (G) which, when composing the coupling, coincides with the common centre (C) of the rotors

(8,9) and with the central axis (HH' ) of the machine shaft ( 3 ) ; and,

for each rotor (8,9), one or several guiding elements (22) designed to be connected to or which are part of the respective rotor (8,9) and/or of the core (21) and with which a uniform rotation of the core (21) and the machine shaft (3) is converted into a non-uniform rotation of the respective rotor (8,9), or vice versa.

Mechanical coupling (20) according to claim 1, characterised in that the core (21) forms an inner portion of the coupling (20) .

3. Mechanical coupling (20) according to claim 1, characterised in that the core (21) forms an outer portion of the coupling (20) .

4. Mechanical coupling (20) according to one or several of the preceding claims, characterised in that the core (21) is formed of a spherical shaped or cross- shaped body.

5. Mechanical coupling (20) according to one or several of the preceding claims, characterised in that the coupling (20) for at least one of the rotors (8,9) comprises one or several of the following guiding elements ( 22 ) :

- a groove (23) or opening in the core (21) which can cooperate with a protrusion (24) on a rotor (8,9) or with another guiding element (22,25);

- a groove (23) or opening in a rotor (8,9) or in an element which needs to be connected thereto, which can cooperate with a protrusion on the core (21) or with another guiding element (22);

- a portion (24) extending radially from the wall of a rotor (8,9) or from an element which is to be connected thereto, directed away from or towards the centre (G) of the core (21) and around which another guiding element (22) is rotatably mounted; and/or, a portion (28) extending radially from the core (21), directed away from or towards the centre (G) of the core (21) around which another guiding element (22,30) is rotatably mounted.

6. Mechanical machine (1) which includes: - an annular, stationary housing (2);

- a machine shaft (3) which is rotatably mounted in the housing ( 2 ) ;

at least two rotors (8 and 9) which can rotate around their rotor axis (ΑΑ',ΒΒ') in the housing (2) and which cooperate with the machine shaft (3);

a toroidal cavity (14) with a centre (C) and a central axis (FF') through this centre (C) which coincides with the rotor axes (ΑΑ',ΒΒ') of the rotors (8,9) ;

- at least one piston (17,18) provided on each rotor (8,9) which is rotatably mounted in the toroidal cavity (14) around the central axis (FF');

and whereby the central axis (HH' ) of the machine shaft (3) stands at a certain angle (Y) in relation to the central axis (FF'), characterised in that the machine (1) is provided with a mechanical coupling

(20), a portion of which is formed by a core (21) which is part of or which is provided on or mechanically connected to the machine shaft (3), whereby the core (21) has a centre (G) situated on the central axis (HH' ) of the machine shaft (3) and which coincides with the centre (C) of the toroidal cavity (14) and whereby a uniform rotation of the machine shaft (3) is associated with an irregular, non-uniform motion of the rotors (8,9) and the respective pistons (17,18) provided thereon, such that the volume of the chambers (27) formed in the toroidal cavity (14) between successive pistons

(17,18) periodically increases and decreases.

7. Mechanical machine according to claim 6, characterised in that the core (21) is an inner core, whereby the rotors (8,9) are provided around this core (21) .

8. Mechanical machine according to claim 6, characterised in that the core (21) is an outer core, whereby the core (21) is provided around the rotors (8,9) .

9. Mechanical machine (1) according to claims 6 or 7, characterised in that the toroidal cavity (14) is confined, on a radially outward side by the stationary housing (2) on the one hand, and on a radially inward side by portions (10) of the first rotor (8) and the second rotor (9) on the other hand.

10. Mechanical machine according to claims 6 or 8, characterised in that the toroidal cavity (14) is confined on a radially outward side by portions (44) of the first rotor (8) and the second rotor (9) on the one hand, and on a radially inward side by the stationary housing (2) on the other hand.

11. Mechanical machine (1) according to claims 6, 7 or 9, characterised in that the machine shaft (3) is provided, at the centre (C) of the toroidal cavity (14), with a central inner portion (21) forming the core (21) of the coupling (20) and in which grooves (23) are provided, and whereby the first and second rotor (8,9) are each provided with at least one carrier (25) which can be moved to and fro in a corresponding groove (23) of the central portion (21) of the machine shaft (3), and whereby a rotation of the machine shaft (3) is accompanied by a movement of the carriers (25) in the respective groove (23), by a rotation of the rotors (8,9) in the housing (2) and by a rotation of the pistons (17,18) in the toroidal cavity (14), and vice versa.

12. Mechanical machine (1) according to claims 6, 8 or 10, characterised in that the machine shaft (3) is mechanically connected to an outer spherical core whose centre (G) coincides with the centre (C) of the toroidal cavity (14) forming the core (21) of the coupling (20) and in which, on the inner wall (46), grooves (23) are provided, and whereby the first and second rotor (8,9) are each provided with at least one carrier (25) which can be moved to and fro in a corresponding groove (23) of the core (21), and whereby a rotation of the machine shaft (3) is accompanied by a movement of the carriers (25) in the respective groove (23), by a rotation of the rotors (8,9) in the housing (2) and by a rotation of the pistons (17,18) in the toroidal cavity (14), and vice versa .

13. Mechanical machine (1) according to claim 11 or 12, characterised in that a piston (17,18) is provided on two diametrically opposed sides (15,16) of each rotor (8,9), whereby the core (21) which is connected to the machine shaft (3) has a spherical shape (21) whose centre (G) coincides with the centre (C) of the toroidal cavity (14), and whereby the spherical shape (21) is provided with grooves (23) .

14. Mechanical machine (1) according to one or several of claims 11 to 13, characterised in that the centre of each groove (23) forms a circular line situated in a plane passing through the machine shaft (3) .

15. Mechanical machine (1) according to claim 14, characterised in that the carriers (25) of the first rotor (8) move in grooves (23) whose centre forms a circular line situated in a first plane passing through the machine shaft (3), and in that the carriers (25) of the second rotor (9) move in grooves (23) whose centre forms a circular line situated in a second plane passing through the machine shaft (3), and whereby the second plane is perpendicular to the first plane.

16. Mechanical machine (1) according to claim 7 and one or several of claims 11 to 15, characterised in that the spherical shape (21) has an outer diameter (I) which corresponds to the inner diameters (J) of the portions (10) of the first and second rotors (8,9) confining the toroidal cavity (14), or, mechanical machine (1) according to claim 8 and one or several of claims 12 to 15, characterised in that the spherical shape (21) has an inner diameter which corresponds to the outer diameters of the portions (44) of the first and second rotors (8,9) confining the toroidal cavity (14) .

17. Mechanical machine (1) according to one or several of claims 11 to 16, characterised in that the carriers (25) can each rotate around a corresponding pivot shaft (24) extending radially from a wall of their respective rotors (8,9) from or towards the central axis (FF') of the toroidal cavity (14) .

18. Mechanical machine according to one or several of claims 11 to 17, characterised in that each rotor

(8,9) is provided with several carriers (25) which are spread over the circumference of the respective rotors (8,9), and in that the core (21) is provided with grooves (23), whereby the carriers (25) move in the grooves (23) during a rotation of the machine shaft (3) so as to achieve at least one cycle whereby the volume of the chambers (27) formed in the toroidal cavity (14) between successive pistons

(17,18) increases from a minimum to a maximum and then decreases again between this maximum and minimum.

19. Mechanical machine according to one or several of claims 11 to 18, characterised in that each rotor (8,9) is provided with one or several pistons (17,18), whereby a carrier (25) is provided in the centre of each piston (17,18) .

20. Mechanical machine according to one or several of claims 11 to 19, characterised in that the centre of each groove (23) forms a curved line, and whereby at least a portion of this curved line is such that the tangent lines to this portion and the central axis (ΗΗ' ) of the machine shaft (3) are not situated in the same plane.

21. Mechanical machine according to one or several of claims 18 to 20, characterised in that the grooves (23) in the core (21) are such that a rotation of the machine shaft (3) at a uniform speed results in a course of the angular velocity of the pistons (17,18) whereby more particularly the angular velocity of a piston (17,18) falls monotonously continuously between a maximum angular velocity and a minimum angular velocity which is equal to zero and rises monotonously continuously between the minimum angular velocity which is zero and the maximum angular velocity .

22. Mechanical machine according to one or several of claims 18 to 21, characterised in that the shape of the grooves (23) is such that one or several of the following situations occurs:

- one revolution of the machine shaft (3) corresponds to several above-mentioned cycles;

- one revolution of the machine shaft (3) corresponds to exactly one above-mentioned cycle; or,

several revolutions of the machine shaft (3) correspond to exactly one above-mentioned cycle.

23. Mechanical machine according to one or several of claims 18 to 22, characterised in that the core (21) is provided with several grooves (23) which cross each other and whereby the rotors (8,9) are provided with several carriers (25) spread regularly or irregularly over the respective rotors (8,9), and whereby the carriers (25) are positioned such or are configured such that the path followed by the carriers (25) in the grooves (23) of the core (21) is unambiguously determined in an intersection.

24. Mechanical machine according to one or several of claims 18 to 23, characterised in that the carriers

(25) are provided with rolling elements such as balls, cylinders and the like, with which the carriers (25) can roll in at least one direction over the walls of the grooves (23) in the core, and/or can undergo a rolling motion in their respective rotors

(8,9) .

25. Mechanical machine (1) according to claim 6, 7 or 9, characterised in that the machine shaft (3) is provided, in the centre (C) of the toroidal cavity

(14), with a core (21) with arms (28) extending radially as of the machine shaft (3), whereby each arm (28) is connected to one of the rotors (8,9) and is provided with a curved element (30) on its far end

(29) for that purpose, which is provided such that it can rotate with one far end (31) around the far end

(29) of the respective arm (28) and which is rotatably mounted with its other far end (32) around a pivot shaft (24) extending radially from a wall of the respective rotor (8,9) to the central axis (FF') of the toroidal cavity (14) .

26. Mechanical machine (1) according to claim 25, characterised in that the core (21) of the machine shaft, together with arms (28), forms a cross (33) whose successive arms (28) are perpendicular to one another and whereby the arms (28) of the cross (33) situated in line with one another are connected to one and the same rotor (8,9) by means of a pair of curved elements (30) whose far ends (31,32) are perpendicular to one another.

27. Mechanical machine (1) according to one or several of claims 6 to 26, characterised in that the machine shaft (3) is bearing-mounted in the housing (2) on either side of the central portion (21) .

28. Mechanical machine (1) according to one or several of claims 6 to 27, characterised in that the angle (Y) between the machine shaft (3) and the central axis (FF') of the toroidal cavity (14) amounts to 45°.

29. Mechanical machine (1) according to one or several of claims 6 to 27, characterised in that the angle (Y) between the machine shaft (3) and the central axis (FF') of the toroidal cavity (14) is adjustable.

30. Mechanical machine (1) according to one or several of claims 6 to 29, characterised in that the housing (2) is provided with one or several inlets and one or several outlets, opening in the toroidal cavity (14) for the supply and discharge of a gas or liquid.

31. Mechanical machine (1) according to claim 30, characterised in that the machine (1) is configured as an engine, whereby air or a gas mixture is supplied via the inlet and exhaust gases are discharged via the outlet, and whereby the machine is provided with a fuel supply and whereby, during the operation of the engine, fuel is combusted in the chambers (27) between the pistons (17,18) in order to move the rotors (8,9) and the machine shaft (3) .

Mechanical machine according to claim 30, characterised in that the machine (1) is configured as a pump or compressor, whereby as a result of a movement of the machine shaft (3), a liquid or gas is drawn in at the inlet and a liquid under pressure or a compressed gas is discharged at the outlet.

Description:
Mechanical machine and coupling suitable for such a mechanical machine.

The present invention first of all relates to a mechanical machine .

The present invention also relates to a coupling which is suitable for such a mechanical machine.

More particularly, the invention relates to mechanical machines, such as for example a compressor or a pump, which are of a type whereby energy which is supplied to make a machine shaft rotate is used for pumping or pressurizing a gas or liquid.

The invention also relates to mechanical machines, such as for example an internal combustion engine or steam engine, which are of a type whereby just oppositely, energy supplied by a gas which has been put under pressure or a liquid which has been put under pressure, is used to make a machine shaft rotate.

A mechanical machine according to the invention may for example also be embodied as a compressed air motor, a fluid pressure motor, a fluid pump, a vacuum pump, an air compressor or gas compressor or even as a filling device.

Many such mechanical machines are already known, but they have certain disadvantages. For example, there are the generally known machines or engines of the type whereby pistons can move back and forth in a cylinder, for example under the pressure of steam or an expanding gas obtained by the combustion of an engine .

A disadvantage of these known machines is that a back and forth motion must be converted in a rotary movement, which is typically achieved by means of a crank shaft to which several piston rods are coupled which in turn provide a power stroke to the machine shaft.

The back and forth going masses in these engines imply a heavy mechanical load and do not allow any high rotational speeds.

There is a rather irregular distribution of force development on the crank shaft, especially for machines with a limited number of cylinders, and relatively large vibrations occur.

With other known mechanical machines, such as the Wankel engine and the so-called toroidal engines, use is made of rotating parts to create chambers in the machine with a periodically increasing and decreasing volume.

These known mechanical machines have the advantage that it is possible to create a motor which is more vibration- free, whereby also higher rotational speeds can be obtained. In the Wankel engine, this is achieved by the eccentric circling of a rotor in a housing.

A toroidal mechanical machine is known for example from US2011100321.

Such a toroidal mechanical machine has an annular, stationary housing in which a machine shaft is rotatably mounted .

The toroidal mechanical machine further comprises a first and a second rotor which are rotatable in the housing and which cooperate with the machine shaft. In the housing is provided a toroidal cavity with a centre and a central axis through this centre which coincides with the central axes of the rotors.

On each rotor is further provided a pair of pistons which are rotatably mounted in the toroidal cavity around the central axis of this toroidal cavity.

The machine shaft is positioned at a certain angle with respect to the central axis of the toroidal cavity.

The rotors are each time coupled to the machine shaft with the aid of what is called a universal joint or cardan j oint . As is known, a rotation at an input shaft can be converted in a rotation at an output shaft with a cardan joint, standing at a certain angle with respect to the input shaft .

Such a universal joint includes a cross whereby each pair of far ends of the arms of the cross situated in line with each other is rotatably connected to one of the shafts to be coupled. To this end, the shafts are provided with a sort of fork at their far ends. Characteristic of such a coupling is that a uniform rotary movement at the input shaft results in a fluctuating rotary movement at the output shaft.

In other applications, this is often not desirable, but in the toroidal, mechanical machine it is just this phenomenon that is made use of.

Indeed, a uniform rotary movement of the machine shaft is in this case often accompanied by an irregular motion of the rotors and the respective pistons provided thereon, such that the volume of the chambers formed in the toroidal cavity between successive pistons periodically increases and decreases, so that a pump effect can be obtained .

Vice versa, a fluctuating motion of the pistons in the toroidal cavity, for example by alternately supplying a gas under pressure or by the combustion of a fuel, will result in a uniform motion of the machine shaft, which is equivalent to a motor operation of the mechanical machine. The operation of a toroidal machine requires that a uniform rotary movement of the machine shaft is accompanied by an irregular motion of the rotors. The sequence of movements of the rotors as a function of the uniform rotary movement of the machine shaft determines the periodic increase and decrease in volume of the chambers, formed in the toroidal cavity between successive pistons, and in general the operational dynamics of the toroidal motor. A different sequence of movements of the rotors results in different operational dynamics of the toroidal machine.

A major disadvantage of a toroidal machine as is known from US2011100321 is that, for a certain angle of the cardan joint, the sequence of movements of the rotors is fixed, as appears for example from fig. 10 in US2011100321. The fixed sequence of movements generated by a universal joint is very unsuitable for many applications :

- at the time when the volume of the chamber increases, one rotor yields energy, while the other one absorbs energy, in the pump effect as well as in the motor operation of the machine. The same applies when the volume of the chamber decreases.

- The volume of the pistons to be provided on each rotor is determined by the sequence of movements of the rotors. In practical embodiments of the universal joint, this piston volume occupies more than half of the volume of the toroidal stationary housing in which the pistons move. As a result, a lot of useful space is lost on the one hand, and the moment of inertia of the rotors and the corresponding pistons is very large on the other hand, leading to large inertia forces and vibrations.

Due to the unfavourable operational dynamics, transmission powers and torques arise which are dozens of times higher than strictly necessary to bring about the intended useful power.

- In an engine operation, the available angle for the fuel injection and/or ignition is very limited, thus limiting the rotational speed of such an engine.

Another major disadvantage of the toroidal mechanical machine as is known from US2011100321 is its complicated construction . The combination of two universal joints for driving rotors that rotate independently of each other around the same central axis of the toroidal cavity requires a mounting whereby one universal joint, in fact, surrounds the other one .

In addition, the transmission of the rotary movement of the machine shaft to a movement of the rotors is associated with large forces, requiring a robust dimensioning of the different components.

On the other hand, the available space in the interior opening of the housing is very limited for such a robust dimensioning, so that it was decided in US2011100321 to place the coupling as a whole outside the core of the machine. Another major disadvantage of the solution of US2011100321 is that a free end of the machine shaft is coupled to the rotors . Said far end of the machine shaft is to be rotatably supported, which requires a heavy design of the bearing and whereby nonetheless, due to deflection of the machine shaft and play in the bearing, vibrations will occur which are difficult to absorb.

It is clear that such a solution is heavy, requires a lot of moving and rotating parts, which is expensive, entails much wear, is difficult to assemble and to maintain, and so on .

Also, the present invention aims to offer a solution to one or several of the above-mentioned and/or other disadvantages . More particularly, the invention aims to offer a toroidal mechanical machine wherein the coupling between the machine shaft and the rotors is very simple on the one hand and can therefore be of a compact and robust construction, and provides a sequence of movements to the rotors on the other hand which optimally adapts the operational dynamics of the toroidal machine to the intended application.

An additional aim of the invention consists in restricting the vibrations in such a toroidal mechanical machine to the lowest possible level. Yet another object of the invention is to provide a low- cost solution whereby use is made of as few parts as possible . Another aim of the invention consists in composing a toroidal mechanical machine whose weight can be significantly reduced compared to the known similar toroidal mechanical machines. To this end, the present invention concerns a mechanical coupling which is suitable for coupling several rotors with a common centre and a common central rotor shaft to a machine shaft, whereby the central axis of the machine shaft and the common rotor axis stand at an angle with respect to one another, whereby the rotors can rotate around the common central rotor axis, whereby the rotors can also mutually move in relation to one another and whereby the coupling comprises the following elements:

- a core which is intended to be firmly connected to or to be part of the machine shaft, with a centre which, when composing the coupling, coincides with the centre of the rotors and with the central axis of the machine shaft; and,

- for each rotor, one or several guiding elements designed to be connected to or which are part of the respective rotor and/or of the core and with which a rotation of the core around the machine shaft is converted into a non ¬ uniform motion of the rotor concerned around the centre of the core or vice versa.

A major advantage of such a mechanical coupling according to the invention is that it has a core with a centre around which all other parts rotate, more particularly the machine shaft as well as the rotors.

A major advantage is that, thanks to the coupling according to the invention, the sequence of movements of the rotors can be adjusted, within certain limits. As a result, the machine can be optimized for its application. Among other things, this has the following advantages:

- a restriction of non-useful power transmissions compared with US2011100321;

- a reduction of the volume of the pistons connected to the rotors. This increases the useful available space in the stationary housing, and the machine can be made more compact. Also the moment of inertia of the rotors and associated pistons is reduced, making the mechanical dynamics more favourable;

a reduction of the necessary transmission powers and torques to transmit a given power, in the pump effect as well as in the engine operation of the machine;

- a wider available angle for the fuel injection and/or ignition in the engine operation of the machine.

Yet another advantage of a mechanical coupling according to the invention consists in that the core is designed to be part of the machine shaft or to be connected to the latter .

This is for example not the case with the conventional universal joint, whereby the cross constitutes a separate element between the shafts to be coupled. Yet another advantage of such a mechanical coupling according to the invention consists in that several rotors can be simultaneously coupled to a machine shaft with only one coupling, while remaining mutually movable in relation to each other.

It is therefore clear that with a mechanical coupling according to the invention, the required number of elements for achieving the coupling of several rotors to a machine shaft is greatly reduced.

In this manner is obtained a very compact mechanism which can be of a robust construction, whereby the power transmission between the machine shaft and the rotors or vice versa is very efficient and produces a minimum of vibrations .

According to a possible embodiment of a mechanical coupling in accordance with the invention, the core forms an inner portion of the coupling, around which the other parts of the mechanical coupling are provided.

A major advantage of this embodiment of a mechanical coupling in accordance with the invention is that it is simple to manufacture and the rotors and pistons are easily accessible, for example for applying conduits for introducing fuel or for discharging exhaust gases and the like . According to another possible embodiment of a mechanical coupling in accordance with the invention, the core forms an outer portion of the coupling, whereby this core is provided around the other components of the mechanical coupling .

An advantage of this embodiment of a mechanical coupling in accordance with the invention is that a very compact configuration can be obtained.

In addition, the action of the guiding elements in this embodiment with an outer core is less subject to frictional forces, whereas less force is required for the transmission of the same torque to the machine shaft when using an outer core than in the embodiment with an inner core . According to a preferred embodiment of a mechanical coupling in accordance with the invention, the core is formed of a spherical or cross-shaped body.

Such cores are simple to manufacture and they can be made very robust.

A mechanical coupling preferably comprises one or several of the following guiding elements for at least one of the rotors :

- a groove or opening in the core which can cooperate with a protrusion on a rotor or with another guiding element; - a groove or opening in a rotor or in an element which needs to be connected thereto, which can cooperate with a protrusion on the core or with another guiding element; - a portion extending radially from the wall of a rotor or from an element which is to be connected thereto, directed away from or towards the centre of the core and around which another guiding element is rotatably mounted; and/or,

a portion extending radially from the core, directed away from or towards the centre of the core around which another guiding element is rotatably mounted.

It is clear that many different embodiments of a mechanical coupling according to the invention can be realised, whereby in some cases grooves can be provided in order to guide the movement of the machine shaft and the rotors in relation to one another.

In such grooves, other elements can make a sliding movement, either or not combined with a rotating movement.

In other cases, the guiding of the movement can be achieved by guiding elements which connect the rotors and the core of the coupling to each other and which are fixed at their ends in a rotatable manner.

A mechanical coupling according to the invention can be used in various applications whereby several rotors need to be coupled to a shaft. However, the invention mainly focuses on improving the above-discussed toroidal mechanical machine and hence concerns such an improved mechanical machine.

More particularly, the invention also concerns a mechanical machine which includes:

- an annular stationary housing; a machine shaft which is rotatably mounted in the housing;

- two or more rotors which can rotate around their rotor axis in the housing and which cooperate with the machine shaft;

a toroidal cavity with a centre and a central axis through this centre which coincides with the rotor axes of the rotors;

at least one piston provided on each rotor which is rotatably mounted in the toroidal cavity around the central axis;

and whereby the machine shaft stands at a certain angle in relation to the central axis, whereby the machine is provided with a mechanical coupling, a portion of which is formed by a core which is part of or which is provided on the machine shaft, whereby the core has a centre situated on the central axis of the machine shaft and which coincides with the centre of the toroidal cavity, and whereby a rotation of the machine shaft is associated with an irregular, non-uniform motion of the rotors and the respective pistons provided thereon, such that the volume of the chambers formed in the toroidal cavity between successive pistons periodically increases and decreases. It is clear that a mechanical machine according to the invention offers all the advantages of a toroidal mechanical machine whereby the pistons rotate around the central axis of the toroidal cavity at speeds which relatively vary from one another, such that an engine operation or pump effect is obtained without any masses moving to and fro. On the other hand, such a mechanical machine according to the invention offers all the advantages of the aforesaid mechanical coupling according to the invention, more particularly a compact and robust configuration, an adapted sequence of movements of the rotors, and a more efficient mechanism from a technical point of view which is simpler and cheaper to manufacture than the known mechanisms which are suitable. In order to better explain the characteristics of the invention, the following preferred embodiments of a mechanical machine according to the invention as well as of a mechanical coupling according to the invention are described by way of example only, with reference to the accompanying figures, in which: figure 1 is an exploded view in perspective of a first rotor of a mechanical machine according to the invention;

figure 2 is a perspective view of that same first rotor in an assembled condition;

figure 3 shows a front view of the first rotor according to arrow F3 in figure 2;

figure 4 shows a section through the first rotor according to the plane indicated by F4-F4 in figure

3;

figure 5 represents a view of the first rotor according to arrow F5 in figure 3;

figure 6 is analogous to figure 2 but with an indication of the non-visible lines in dotted lines; figures 7 to 12 represent a second rotor of the machine according to the invention in a manner analogous to figures 1 to 6;

figure 13 is a perspective view of the machine shaft of a mechanical machine according to the invention on which is provided a spherical core of a coupling according to the invention; this is a possible embodiment in which the core forms the inner portion of the coupling;

figures 14 and 15 show views of the machine shaft according to arrows F14 and F15 in figure 13;

figure 16 shows a section through the core of the machine shaft according to a plane indicated by F16- F16 in figure 15;

figure 17 is an exploded view in perspective of a first embodiment of a mechanical machine according to the invention, at least the essential elements thereof;

figure 18 represents the same components of the mechanical machine from figure 17 as assembled;

figure 19 shows a view on the mechanical machine according to the invention in a direction indicated by arrow F19 in figure 18;

figure 20 is a section through the mechanical machine according to arrow F20 in figure 19;

figure 21 shows a view on the mechanical machine according to arrow F21 in figure 19;

figures 22 and 23 are sections through the mechanical machine, according to the planes which are indicated by F22-F22 and F23-F23 respectively in figures 21 and

19; figures 24 to 29 show the mechanical machine from figure 19 in perspective again with a portion of the housing being omitted, in respective successive positions during its operation;

figures 30 to 34 represent the same positions as in figures 24 to 29, but in plan view;

figures 35 to 39 represent sections through the mechanical machine omitting a portion of the housing in the successive positions according to planes indicated by F35-F35 to F39-39 respectively;

figures 40 to 44 illustrate the same successive positions in perspective with the omission of the machine shaft and the entire housing;

figures 45 to 49 are plan views of the positions represented in figures 40 to 44 respectively;

figures 50 to 54 show views according to arrows F50 to F54;

figures 55 to 59 represent the machine shaft in successive positions corresponding to the positions of figures 40 to 44, seen in perspective;

figure 60 shows a view as in figure 19 of a second simple embodiment of a mechanical machine according to the invention;

figure 61 represents the same view as in figure 60 with the omission of the housing and the second rotor with its connections to the core of the machine shaft ;

figure 62 is a perspective view of the condition represented in figure 61;

figures 63 and 64 illustrate in a manner analogous to figures 61 and 62 a second simple embodiment of a mechanical machine according to the invention, but this time omitting the housing and the first rotor and its connections to the core of the machine shaft; figures 65 to 68 represent a guiding element used in the mechanical machine according to a second simple embodiment, seen in perspective and according to views indicated by arrows F66 to F68 respectively; figure 69 shows a view on the machine shaft of the mechanical machine according to a second simple embodiment ;

figure 70 is an internal section through the core, provided on this machine shaft according to a plane indicated by F71-F71;

figure 71 shows the machine shaft from figure 70 in perspective ;

figure 71 bis is a graph whereby a possible course of the angular velocity of the rotors is plotted in relation to the angular rotation of the machine shaft ;

figure 72 is a graph whereby another possible course of the angular velocity of the rotors is plotted in relation to the angular rotation of the machine shaft ;

figures 73 to 75 illustrate how a point W on a sphere can be specified by means of two angles U and V, according to a longitude and latitude respectively; figures 76 to 78 show possible paths on a spherical surface which may serve for grooves in which carriers of a mechanical machine according to the invention can move;

figure 79 shows a view on a carrier provided in the groove of a core of a mechanical machine and which is provided with roller elements for a rolling movement over the walls of the groove concerned;

figure 80 shows a section through a portion of a rotor and the core of a mechanical machine in accordance with the invention at the location of a carrier, whereby this carrier is provided with roller elements for a turning and rolling movement of the carrier in the rotor portion;

figure 81 shows a section through a mechanical machine according to the invention whereby the core is an external spherical core provided with the machine shaft on one side; and,

figure 82 shows a section of another embodiment of a mechanical machine according to the invention with a core which is an external spherical core on which is provided an external toothing to drive the machine shaft .

The mechanical machine 1 according to the invention which is schematically represented in figure 17 and 18 includes a number of components which will be further discussed in detail one by one.

The mechanical machine 1 has an annular, stationary housing 2 with an inner diameter D which forms the outer structure of the machine 1 and a machine shaft 3 which is rotatably mounted in this housing 2.

The housing 2 as shown is only to illustrate the operating principle and may have a completely different, more practical form in practice which is more suitable, for example, to place the housing 2 on a substrate. The stationary housing 2 is in this case composed of a cylindrical wall 4 forming the radial outer side of the machine 1 and a pair of circular lids 5 and 6, both provided with an internal, circular opening 7.

The lids 5 and 6 are firmly connected to the cylindrical wall 4, which is not represented in detail in the figures. In the housing 2 are further provided a first rotor 8 and a second rotor 9 which can rotate around their rotor axes AA' and BB' respectively in the housing 2, and which cooperate with the machine shaft 3. The first rotor 8 is shown in more detail in figures 1 to 6, whereas the second rotor is shown in more detail in figures 7 to 12, both in a position in relation to each other as they are mounted in the machine 1. The rotors 8 and 9 are made identical and they are mainly formed of a cylindrical ring 10 with an external diameter E, whereby they are provided on their heads 11 with a circular recess 12 having dimensions corresponding to the dimensions of the interior opening 7 in a lid 5 or 6, so that such a lid 5 or 6 can be applied in a fitting manner over a respective rotor 8 or 9.

The rotors 8 and 9 are mounted with their feet 13 adjacent but movable with respect to one another in the machine 1, in such a manner that their rotor axes AA' and BB' are situated in line with each other. After the assembly of the rotors 8 and 9 in the housing 2, a toroidal cavity 14 is thus formed in the machine 1, which is confined on a radially outward side by the stationary housing 4 and in the axial direction AA' or BB' by the lids 5 and 6 on the one hand, and on a radially inward side by the cylindrical rings 10 of the first rotor and the second rotor 8 and 9 on the other hand.

This toroidal cavity 14 has a centre C and a central axis FF' through this centre C which coincides with the rotor axes AA' and BB' of the rotors 8 and 9.

The centre C may also be regarded as the centre of the combination of the rotors 8 and 9.

Between each lid 5 and 6 and the corresponding rotor 8 or 9, near the circular opening 7, is preferably provided a bearing, not shown in the figures, to make the rotation of the rotors 8 and 9 in the housing 2 proceed effortlessly.

On two diametrically opposed sides 15 and 16 of each rotor 8 and 9 is in each case provided a piston, more particularly pistons 17 on the rotor 8 and pistons 18 on the second rotor 9.

These pistons 17 and 18 have, apart from a little play, a shape that corresponds to a portion of the toroidal cavity 14 having a cross section 19, an inner diameter E and an outer diameter D.

This portion hereby forms a sector with angle X of the entire toroidal cavity 14. In the given embodiment, this portion of the toroidal cavity 14 corresponds to a sector spanning an angle X of approximately 68°.

The pistons 17 and 18 are firmly mounted on their corresponding rotors 8 and 9 and they thus rotate along with said rotors 8 or 9 in the toroidal cavity 14. The machine shaft 3 is at a certain angle Y in relation to the central axis FF' of the toroidal cavity 14, whereby this angle Y in this case amounts to 45°. Other embodiments with other angles X and Y are also possible according to the invention. For example, for an angle Y of 30°, X is approximately 81°. For an angle Y of 60°, X is approximately 48°.

In more optimized embodiments, which will be discussed further, for a given angle Y, the angle X may be strongly reduced.

In order to make the rotors 8 and 9 cooperate with the machine shaft 3, the machine 1 is provided with a mechanical coupling 20 according to the invention.

The central portion 21 of this coupling 20 is formed of a core 21 which is in this case part of the machine shaft 3, but which may also consist of a separate part which is fixed to the machine shaft 3. In another embodiment, the central portion 21 can also be made as an outer core, as will be described later. The core 21 also has a centre G situated on the central axis HH' of the machine shaft 3 and which coincides with the centre C of the toroidal cavity 14. As is shown in more detail in figures 13 to 16, the machine shaft 3 has a central portion 21 with a spherical shape, whose centre G coincides with the centre C of the toroidal cavity 14. The spherical core 21 has an outer diameter I which practically corresponds to the inner diameters J of the cylindrical portions 10 of the first and second rotors 8 and 9 confining the toroidal cavity 14. In the given embodiment, the core 21 of the coupling 20 also has guiding elements 22 in the shape of grooves 23 for each rotor 8 or 9, provided in the spherical core 21.

These grooves 23 start as of the machine shaft 3, whereby the centre of each groove 23 forms a circular line situated in a plane passing through the machine shaft 3.

In this case, four such grooves 23 are provided which are each successively rotated at an angle of 90° in relation to the central axis HH' .

The grooves have a width K.

Each rotor 8 and 9 is further provided with guiding elements 22 in the shape of a pair of pivot shafts 24, whereby the pivot shafts 24 extend towards each other and are situated in line with each other in a direction towards the centre C of the toroidal cavity 14.

These pivot shafts 24 are in this case part of the rotors 8 and 9, but they may also form separate components.

In this first embodiment, the coupling 20 further comprises also other elements 22 for each rotor 8 and 9 in the shape of carriers 25 which are connected to the respective rotor 8 or 9.

More particularly, every carrier 25 is provided with an opening with which it is disposed around a corresponding pivot shaft 24, whereby said carrier 25 can rotate around the pivot shaft 24 concerned.

The carriers 25 further have an outer shape which fits in a groove 23 of the spherical core 21, and to that end they are slightly curved so as to be able to slide smoothly over the spherical shape 21.

Embodiments whereby the carriers roll instead of slide in the grooves 23 are also possible according to the invention. The carriers 25 may for example be configured as wheels, mounted on the pivot shafts 24.

The coupling 20 between the rotors 8 and 9 and the machine shaft 3 aims to convert a uniform rotation of the core 21 around the machine shaft HH' in a non-uniform motion of the respective rotors 8 and 9 around the axes AA' and BB' or, vice versa, to convert a non-uniform motion of the rotors 8 and 9 around the rotor axes AA' and BB' in a uniform rotation of the machine shaft 3.

In this first embodiment of a mechanical machine 1 according to the invention, this is achieved by directing the rotors 8 and 9 in such a way towards each other during the assembly that the carriers 25 of the first rotor 8 move in grooves 23 whose centres form a circular line situated in a first plane passing the machine shaft 3, and the carriers 25 of the second rotor 9 move in grooves 23 whose centres form a circular line situated in a second plane passing through the machine shaft 3 and whereby the second plane is perpendicular to the first plane. This is illustrated for example in figures 19 to 23.

Thus, a rotation of the machine shaft 3 is accompanied by a movement of the carriers 25 in their respective grooves 23, by a rotation of the rotors 8 and 9 in the housing 2 and by a rotation of the pistons 17 and 18 in the toroidal cavity 14, and vice versa.

A uniform rotation of the machine shaft 3 is thus accompanied by an irregular, non-uniform motion of the rotors 8 and 9 and of the respective pistons 17 and 18 provided thereon, such that the volume of the chambers 27 formed in the toroidal cavity 14 between successive pistons 17 and 18 periodically increases and decreases. This is illustrated by means of figures 24 to 59. The different sets of figures each represent, from left to right, successive steps whereby the machine shaft 3 is rotated 22.5° around the axis HH' at each subsequent step. In short, figures 24 to 59 together show how the different components of the machine 1 move during a rotation of the machine shaft over 90°.

In the position according to figure 45, the centres of the pistons 17 of the first rotor 8 are situated in the plane through the machine shaft 3 perpendicular to the lids 5 and 6 of the machine 1, whereas the centres of the pistons 18 of the second rotor 9 are situated in the plane perpendicular thereto and perpendicular to the lids 5 and 6.

In the position according to figure 49, i.e. after a rotation of the machine shaft over 90°, the situation is just the other way around and the centres of the pistons 18 of the second rotor 9 are situated in the plane through the machine shaft 3 perpendicular to the lids 5 and 6 of the machine 1, whereas the centres of the pistons 17 of the first rotor are situated in the plane perpendicular thereto and perpendicular to the lids 5 and 6.

In both aforementioned positions, the volume of all the chambers 27 is equally large.

The intermediate position shown in figure 47 and all other relevant figures, more particularly when the machine shaft 3 is rotated over 45° in relation to the initial position as shown in figure 45, represents a totally different situation .

The mechanical coupling is such that during said rotation of 45°, the first rotor 8 makes a slower progress than the second rotor 9, such that in the position of figure 47, the pistons 17 and 18 almost touch each other.

Thus, the volume in certain chambers 27 is hereby reduced to practically zero whereas the volume in the other chambers 27 has increased to a maximum.

On further rotating the machine shaft 3 over another 45° the reverse occurs, more particularly in the transition shown in figures 47 to 49 and all the corresponding figures of the other series.

The first rotor 8 hereby accelerates in relation to the second rotor 9.

With each further rotation of the machine shaft over 90° the above-mentioned phenomenon is repeated, so that the chambers 27 thus increase and decrease in volume periodically .

It is clear that such a mechanical machine 1 can be used as an engine or as a pump or compressor.

To that end, it is sufficient to provide one or several inlets and outlets at the appropriate places in the housing 2 which flow in the toroidal cavity 14 for feeding and discharging a gas or liquid. The number of inlets and outlets can hereby be adjusted as a function of the machine to be obtained. For example, the mechanical machine 1 according to the invention can be configured as an engine fitted with a fuel supply, whereby a gas mixture is supplied via said inlet and exhaust gases are discharged via an outlet, and whereby during the operation of the machine 1, fuel is combusted in the chambers 27 between the pistons 17 and 18 in order to make the rotors 8 and 9 move in relation to one another and, via the coupling 20, thus also make the machine shaft 3 move. The mechanical machine 1 can be configured as a four- stroke engine whereby, per chamber 27 and per revolution, four phases are completed: more particularly, a first phase in which air and possibly fuel are drawn in, a second phase in which the gas mixture is compressed, a third phase in which the gas mixture is detonated, either or not with a fuel injection, and work is delivered, and a fourth phase in which the combusted gases are removed via an exhaust. However, it is not excluded to implement the invention as a two-stroke engine or to design entirely other configurations .

In another embodiment, the machine 1 can be configured as a pump or compressor, whereby thanks to a movement of the machine shaft 3, a liquid or gas is drawn in at the aforesaid inlet and a liquid under pressure or a compressed gas is discharged at an outlet.

Such provisions are more than well known according to the present state of the art.

It is clear that with the solution offered by the present invention, a mechanical machine 1 is obtained which can run much more smoothly, is easy to manufacture and is composed of relatively few elements.

Another advantage of the mechanical machine 1 according to the invention is that the machine shaft 3 can be bearing- mounted in the housing 2 on either side of the central portion 21, which allows for a much more solid support of the machine shaft 3 with less vibrations than with similar, known machines.

In another possible embodiment, the mechanical machine 1 can be configured for example as a measuring and filling machine for gases (for example for filling balloons), liquids (for example for filling beverage containers), emulsions (for example for filling up yoghurt) or granules (for example drugs) .

The filling is hereby drawn in or blown in via an inlet of the mechanical machine 1, and a measured filling is deposited in a package via an outlet. In an embodiment of a mechanical machine 1, as represented in figures 17 and 18, this requires two inlets and two outlets per revolution . By making the angle Y adjustable, for example by positioning the machine shaft 3 such that it can be tilted, a correct dosage can be set. With a smaller angle Y, a smaller amount will be pressed from an outlet in this case.

Figures 60 to 71 represent yet another embodiment of a mechanical machine 1 according to the invention, which is entirely analogous to the preceding embodiment save for the coupling 20 between the rotors 8 and 9 and the machine shaft 3.

In this embodiment, at the position of the centre C of the toroidal cavity 14, the mechanical machine 1 is provided with a core 21 with arms 28 extending radially from the machine shaft 3.

Each arm 28 is hereby connected to one of the rotors 8 or 9.

To that end, each arm 28 is provided with a guiding element 22 in the shape of a curved element 30 on its far end 29, shown in more detail in figures 65 to 68. Such a curved element 30 is provided such that it can pivot with one far end 31 around the far end 29 of the respective arm 28 and such that it can pivot with its other far end 32 around one of the pivot shafts 24 extending radially from the cylindrical portion 10 of the rotors 8 and 9 towards the central axis FF' of the toroidal cavity 14. In the given embodiment, the core 21 on the machine shaft forms a cross 33 whose successive arms 28 are perpendicular to each other, which is shown in more detail in figures 69 to 71.

The arms 28 of the cross 33 which are situated in line with each other are hereby connected to one and the same rotor 8 or 9 by means of a pair of curved elements 30 whose far ends 31 and 32 are at right angles.

According to the invention it is not excluded, however, to provide more or less arms 28 or to use entirely different couplings 20 to achieve a mechanical machine 1 according to the invention.

An interesting development of a mechanical machine 1 according to the invention may consist in making the angle Y between the machine shaft 3 and the central axis FF' of the toroidal cavity 14 adjustable and/or the angle X spanned by the pistons 17 and 18, which makes it possible to play with the volumes in the chambers 27 as a function of the application.

The essence of a mechanical coupling 20 or a mechanical machine 1 according to the invention is that a uniform rotation of the machine shaft 3 is accompanied by an irregular, non-uniform motion of the rotors 8 and 9 and of the respective pistons provided on the latter. However, many different irregular, non-uniform motions of the rotors are possible, each leading to a different sequence of movements of the rotors and to different operational dynamics of the toroidal machine. Figure 71 bis shows the course of the angular velocities P and Q of the rotors 8 and 9 respectively as a function of the angular rotation U of the machine shaft 3 in relation to an initial position, i.e. for a mechanical machine 1 according to the invention in the first simple embodiment as described in figures 13 to 59 included.

A major advantage of the mechanical machine according to the invention, however, is that many very different motion sequences of the rotors 8 and 9 can be achieved.

As an example, figure 72 shows another practically achievable course of the angular velocities P and Q of the rotors 8 and 9 respectively as a function of the angular rotation U of the machine shaft 3 in relation to an initial position.

In order to make the mechanical coupling 20 of a mechanical machine 1 according to the invention operate as efficiently as possible, the sequence of movements of the rotors can be adjusted to specific targets.

A first target concerns the torques and forces in the mechanical coupling 20. An important fact to obtain a properly working mechanical machine 1 according to the invention which serves as an engine consists in converting the movement of the pistons 17 and 18 under the influence of expanding gases in a movement of the machine shaft 3, whereby a torque which is as constant as possible is delivered to said machine shaft 3. It is clear that in a mechanical machine 1 according to the invention, the expansion of a gas in a chamber 27, for example supplied in the chamber 27 concerned by the ignition of a fuel, is accompanied by the divergence of the successive pistons 17 and 18 concerned, whereby this provides for a positive contribution to the advancement of the machine shaft 3 at the leading piston, as well as a negative contribution to the trailing piston, of the pistons 17 and 18 enclosing the chamber 27.

Every different irregular, non-uniform motion of the rotors 8 and 9 thus leads to a different driving torque of the rotors 8 and 9. Moreover, every different irregular, non-uniform motion of the rotors 8 and 9 also leads to a different acceleration of the rotors, which in turn gives rise to a different inertia torque of the rotors. It is clear that the driving torques and inertia torques of the rotors 8 and 9 together determine the torques and forces in the mechanical coupling 20. By selecting a different sequence of movements of the rotors, one can thus control these torques and forces.

The sequence of movements from figure 72 leads for example to torques in the mechanical coupling 20 which are more than 10 times smaller than those in figure 71 bis. A second aim of the optimization of the sequence of movements of the rotors 8 and 9 regards the angle X covered by the pistons 17 and 18 in the toroidal cavity 14. The smaller the angle X, the more space from the toroidal cavity 14 can be put to use, both in the engine operation and in the pump or compressor operation. A smaller angle X therefore allows to make the mechanical machine more compact. In addition, a smaller angle X also leads to a smaller inertia torque of the rotors. As explained above, the resulting torques and forces in the mechanical coupling 20 will decrease. The sequence of movements from figure 72 leads for example to an angle X of approximately 15°, compared to an angle X of approximately 68° for the sequence of movements from figure 71 bis. It is clear that, apart from the optimization of the motion cycle of the rotors 8 and 9, many other parameters can be taken into account as well. For example, for the engine operation, the available time frame for fuel injection can be maximized, or the speed of the rotors at the ignition can be minimized.

In order to obtain such a course of the angular velocities P and Q from figure 72 during the operation of a mechanical machine 1 according to the invention, a number of factors can be influenced.

A first possibility consists in adjusting the shape of the grooves 23 in the core 21. Indeed, the grooves 23 in the core 21 must not necessarily be designed such that the centres of the grooves 23 form a circular curve situated in a plane through the central axis HH' of the machine shaft 3, as was always the case in the above-described embodiments.

Indeed, the aim is to provide each rotor 8 or 9 with several carriers 25 spread over the circumference of the rotor 8 or 9 concerned, and to provide the core 21 with grooves 23, whereby the carriers 25 move in the grooves 23 during a rotation of the machine shaft 3 in order to achieve a cycle whereby the volume of the chambers 27 formed in the toroidal cavity 14 between successive pistons 17 and 18 increases from a minimum to a maximum and then decreases again between this maximum and minimum.

The angular velocity of the rotors 8 and 9 may hereby vary strongly depending on the shape that is selected for the grooves 23.

For example, it is not excluded to configure the grooves 23 such that their centres form curved lines, whereby at least a portion of this curved line is such that the tangent lines to this portion and the central axis HH' of the machine shaft 3 are not situated in one and the same plane . Figures 76 to 78 show some possible examples of possible curves 34 representing the centre of a groove 23.

To understand these figures 76 to 78, reference is first made to figure 73 to 75.

Figure 73 shows a spherical core 21 provided with such a curve 34. In order to represent the shape of said curve 34 in a planar graph, every point W of a curve 34 on the core 21 is indicated by means of the spherical coordinates U and V, whereby the U-coordinate in figures 76 to 78 is represented horizontally and the V-coordinate is plotted vertically .

U hereby represents the degree of longitude, i.e. the angle U between a reference plane 35 through the machine shaft 3 and a meridian 36 through the machine shaft 3 and the point W.

V represents the degree of latitude and is the angle V between the equatorial plane 37 and a radian 39 from the centre G of the core 21 to the parallel of latitude 38 transverse to the machine shaft 3 passing the point W.

Figure 76 represents a number of possible curves 34 whereby it is clear that, in practice, some characteristics of such curves 34 may lead to problems to make one or several carriers 25 move in a groove 23 designed according to such a curve 34.

Firstly, singularities occur in certain types of curves 34. In one singularity, the carrier concerned of the rotor can move freely in relation to the core and the machine shaft. In order to prevent the rotor from moving freely as a whole, another carrier must provide for a correct coupling with the core and thus with the machine shaft on that same rotor. Figure 77 shows the same curves 34 as in figure 76, whereby portions of the curves 34 in which such a singularity occurs have been removed from the curve concerned, however.

Further, other portions of a curve 34 in some cases overlap somewhat. In figure 78, these portions with an overlap have been removed as well from the curves 34 represented in figure 76.

In this manner, it is possible to design curves 34 that are practically useful for guiding the carriers 25 in grooves 23 in a core 21 manufactured according to these curves 34. Thus, the curves 34 according to figures 76 to 78 are designed to achieve the sequence of movements from figure 72.

By varying the shape of the curves 34, one can thus optimize the characteristics of the mechanical machine 1 according to the invention. In the embodiment of a mechanical machine 1 according to the invention, as represented in the figures, a periodical four-stroke cycle with two volume increases and two volume decreases of a chamber 27 always corresponds to a rotation of the machine shaft of 360°, which can be clearly derived for example from figures 24 to 29.

This is not necessarily the case according to the invention, and it is also possible, for example, to adjust the shape of the grooves 23 in such a way that one of the following situations occurs:

- one revolution of the machine shaft 3 corresponds to several of the above-mentioned cycles; - one revolution of the machine shaft 3 corresponds to exactly one above-mentioned cycle; or,

- several revolutions of the machine shaft 3 correspond to exactly one above-mentioned cycle.

Further, in the embodiments of a mechanical machine 1 according to the invention, each rotor 8 or 9 is provided with two pistons 17 and 18 whereby a carrier 25 is each time provided in the centre of each piston 17 and 18.

A possible variant according to the invention may consist in providing more than two pistons on a rotor 8 or 9.

Additionally, or as another feasible embodiment, it is also possible to provide more or less carriers 25 on a rotor 8 or 9, not necessarily in the centre of a piston 17 or 18; on the contrary, several positions on the rotors 8 and 9 can be selected to that end, for example to facilitate the movement of the carriers 25 during a rotation of the rotors 8 and 9 in the respective grooves 23.

For example, according to a particular embodiment, the core 21 can be provided with several grooves 23 crossing one another and whereby the rotors 8 and 9 are provided with several carriers 25 spread regularly or irregularly over the respective rotor 8 or 9 and whereby the carriers 25 are positioned or configured such that the path followed by the carriers 25 in the grooves 23 of the core 21 is unambiguously determined in an intersection. It is clear that, by varying and combining all these parameters, the operation of a mechanical machine 1 according to the invention can be optimized. Another aspect which, according to the invention, can contribute to a better guiding of the carriers 25 in grooves 23 of the core consists in providing the carriers 25 with rolling elements 40, such as balls, cylinders and the like, with which the carriers 25 can roll in at least one direction over the walls 41 of the grooves 23 in the core 21 and/or can undergo a rolling motion in their respective rotors 8 or 9.

Such a carrier 25 provided with rolling elements 40 with which the carrier can roll over the walls 41 is represented by way of example in figure 79.

In figure 80, the carrier 25 is also provided with rolling elements 40 whereby more particularly the rolling elements 40 are part of a bearing 42 which rotatably supports the pivot shaft 24 of the carrier 25 in the rotor 8.

In all the embodiments of a mechanical machine 1 in accordance with the invention illustrated so far, the core 21 is an inner core 21, whereby the rotors 8 and 9 are provided around this core 21.

Figure 81 represents an alternative embodiment whereby the core 21 is an outer core provided around the rotors 8 and 9. The toroidal cavity 14 is hereby confined, on a radially outward side 43 by portions 44 of the first rotor 8 and the second rotor 9 on the one hand, and on a radially inward side 45 by the stationary housing 2 on the other hand.

Furthermore, the core 21 still forms an essentially spherical shape that is hollow inside and which has an inner wall 46 in which grooves 23 are provided and in which carriers 25 provided on the rotors 8 and 9 can move.

In the case of figure 81, the machine shaft 3 is provided directly on the outer core 21, whereby this machine shaft 3 extends on only one side of the core 21.

Naturally, this requires a robust bearing 47 so as to rotatably support the machine shaft 3.

The hollow, spherical core 21 is provided with an opening 48 on one side for providing feed and discharge pipes, for example for the supply of fuel and the discharge of exhaust gases to and from the chambers 27.

Figure 82 shows yet another embodiment whereby the core 21 is an outer core 21, but whereby said core 21 is this time provided with an opening 49 on either side.

The outer side of the core 21 is provided with a toothing 50 which meshes with a pinion 51 provided on the machine shaft 3.

The core 21 is further rotatably supported by bearings 52. This embodiment offers the advantage that a much more robust construction is obtained and that a slow operation of the mechanical machine 1 nevertheless results in a sufficiently fast rotation of the machine shaft 3.

The invention is by no means restricted to the illustrated embodiments of a mechanical machine 1 and a mechanical coupling 20 according to the invention, described by way of example and represented in the accompanying drawings; on the contrary, such a mechanical machine 1 and mechanical coupling 20 can be achieved in many other ways while still remaining within the scope of the invention.