TRANSMISSION ARRANGEMENT FOR A ROTARY MACHINE

FIELD OF THE INVENTION

This invention relates to a transmission arrangement for a rotary machine.

The transmission arrangement is suitable for use with a rotary machine of the type disclosed in the Applicant's co-pending PCT Patent Application No. PCT/IB2006/054448, which was published on 31 May 2007 under International publication number WO 2007/060642, but is not limited to such an application. The disclosure in the aforesaid PCT Patent Application is included herein by way of reference.

BACKGROUND TO THE INVENTION

PCT Patent Application No. PCT/IB2006/054448 referred to above discloses an arrangement wherein a rotary motor comprises:

a first rotor member rotatable about a first axis; a second rotor member rotatable about a second axis; and a transmission system for rotating the first rotor member and the second rotor member; the first rotor member and the second rotor member being adapted to rotate at variable angular velocities characterised in that in a 360° cycle of the rotors, from a starting position the first

rotor is rotated at a first average angular speed, and the second rotor at a different average angular speed for part of a revolution, and thereafter the average angular speed of the first rotor and the average angular speed of the second rotor are changed for a subsequent part of a revolution so that after 360° rotation of the rotors, the rotors again assume the starting position

It is therefore necessary to provide a transmission arrangement that will be suitable for transmitting the variable angular speed and oppositely directed rotation of the two rotor members to a single drive shaft with a constant angular speed and unidirectional rotational output Likewise, it is also necessary to provide the inverse, i e a transmission arrangement that will be suitable for transmitting constant angular speed and unidirectional rotational input on a drive shaft to variable angular speed and oppositely directed rotation of the two rotor members

OBJECT OF THE INVENTION

An object of the present invention is to provide a novel transmission arrangement for a pair of rotors which inter-engage with one another to form a rotary machine in the nature of an engine, pump, compressor or the like

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a transmission arrangement for controlling a rotary machine including a first rotor being rotatable about a first axis and a second rotor being rotatable about a second axis, the first and second rotors rotating at variable angular velocities in that, in a 360° cycle of the rotors, from a starting position the first rotor is rotated at a first average rotational velocity, and the second rotor at a different average rotational velocity for part of a revolution and thereafter the average rotational velocity of the first rotor and the average rotational velocity of the second rotor are changed for a subsequent part of a revolution so that after 360° rotation of the rotors, the rotors again assume the starting position, the transmission arrangement comprising a contoured disc provided with contours, which disc is co-axially mounted to rotate with one of the rotors of the rotary machine; and a follower for engaging the contours of the contoured disc and which follower extends from a follower disc that rotates about an axis that is parallel to and displaced from the axis of rotation of its associated contoured disc, the transmission arrangement being characterised in that it transmits the variable angular speed and oppositely directed rotation of the two rotors to a single drive shaft with a constant angular speed and unidirectional rotational output and is also suitable for transmitting constant angular speed and unidirectional rotational input on a drive shaft to variable angular speed and oppositely directed rotation of the two rotors.

The transmission arrangement may include two similar contoured discs, each being mounted co-axially with one of the rotors of the rotary machine, and two follower discs, each including a plurality of followers, the arrangement being such that the followers of each follower disc engages one of the contour discs via the contours.

Each follower disc may be rotationally coupled to a gear wheel, the gear wheels having gear teeth that mesh with one another so that the gear wheels rotate in opposite directions.

The gear wheels may cause the follower discs to rotate, the arrangement being such that the gear wheels rotate the follower discs in opposite directions, which in turn engage the contoured discs to drive the latter in opposite directions, resulting in the rotors rotating in opposite directions, so that the angular speed of the rotors are controlled by the contours on the contoured discs.

Alternatively, rotation of the rotors may cause the contoured discs to rotate, which in turn rotates the follower discs via the engaged followers and thus in turn rotates the gear wheels.

The outer periphery of each contoured disc may define the contours.

Alternatively, the contours may be in the form of channels defined by the surface of each contoured disc.

Each follower may be a pin, which is constrained to follow the contours.

The contours may include a first section in which the contour exerts a force on the follower, or vice-versa, and a second return section where substantially no force is exerted between the follower and the contour.

The contours may be wider at selected locations so as to provide specific zones where no force is transmitted, thus preventing potential stalling of the transmission arrangement at top dead centre.

Each contoured disc may include two sets of contours, wherein the one set may be deeper than the other set.

Preferably, each set of contours may include six contours equally spaced about the contoured disc.

Each follower disc may have two sets of followers, wherein the one set of followers may protrude further from the follower disc than the other set of followers so as to engage the set of contours having a greater depth.

Preferably each set of followers may include six followers spaced about the contoured disc.

According to a second aspect of the invention there is provided a method of inducing rotation of a pair of rotors of a rotary machine, the method including the steps of:

- providing a transmission arrangement including contoured discs having contours and which are co-axially mounted to rotate with the rotors, follower discs having followers which engage the contours and a gear wheel coupled to each follower disc;

- causing the gear wheels to rotate the follower discs in opposite directions;

- driving the contoured discs in opposite directions owing to the followers of the follower discs engaging the contours of the contoured discs;

- rotating the rotors in opposite directions, which rotation is caused by the rotation of the contoured discs; and

- controlling the rotational velocities of the rotors by the contours of the contoured discs.

The contours of the contoured discs may be such that when the followers engage the contours on a disc, the angular speed of a first rotor is increased progressively, while the angular speed of the second rotor is reduced progressively during one cycle, and thereafter the angular speed of the first

rotor is decreased progressively and the angular speed of the second rotor is increased progressively until the starting rotational velocities of the rotors angular speeds are again reached.

According to a third aspect of the invention there is provided a method of transmitting rotation caused by a pair of rotors of a rotary machine, the method including the steps of: providing a transmission arrangement including contoured discs having contours and which are co-axially mounted to rotate with the rotors, follower discs having followers which engage the contours and a gear wheel coupled to each follower disc; rotating the rotors in opposite directions;

- causing the contoured discs to rotate, which rotation is caused by the rotation of the rotors; - driving the follower discs in opposite directions, owing to the followers engaging the contours of the contoured discs; and

- causing the gear wheels coupled to the follower discs to rotate.

Further according to this aspect of the invention, the contours of the contoured discs are such that when the follower engages the contour on a disc, the angular speed of a first rotor is increased progressively, while the angular speed of the second rotor is reduced progressively during one cycle, and thereafter the angular speed of the first rotor is decreased progressively and

the angular speed of the second rotor is increased progressively until the starting rotational velocities of the rotors angular speeds are again reached.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described by way of a non-limiting example, and with reference to the accompanying drawings in which:

Figure 1 shows an exploded perspective view of the transmission arrangement for a rotary machine in accordance with the invention;

Figure 2 shows the exploded view of Figure 1 from a different angle;

Figure 3 is a perspective view of the assembled transmission arrangement and rotary machine;

Figure 4 shows the assembled transmission arrangement and rotary machine of Figure 3 from a different angle;

Figure 5 is a top plan view of the transmission arrangement;

Figure 6 shows a plan view of a contoured disc of the transmission arrangement;

Figure 7 shows a graph of rotor displacement against output axle (or drive gear) displacement,

Figure 8 is a perspective view from the front of a second embodiment of the transmission arrangement,

Figure 9 is a perspective view from above of the transmission arrangement of figure 8,

Figure 10 is a front view of the transmission arrangement of figure 8, and

Figure 11 is a top view of the transmission arrangement of figure 8

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings, in which like numerals indicate like features, a transmission arrangement for use with a rotary machine is generally indicated by reference numeral 10

The rotary machine 20 is in the form of the rotary machine as disclosed in the applicant's co-pending patent application PCT/IB2006/054448 (International publication number WO 2007/060642), the content of which is incorporated

herein by reference. The rotary machine 20 comprises two rotors 21 that are adapted to rotate in opposite directions. Each of the rotors 21 includes a plurality of vanes 21.1 and troughs 21.2 that meshes with the other identical adjacent rotor 21 in order to give effect to the workings of the rotary machine 20 discussed in the prior application. The rotors 21 are coupled to rotor shafts 22 that rotate within a housing 23. The housing 23 also serves to form an enclosed volume in which the rotors 21 rotate, whilst also providing support for the rotor shafts 22. Opposing ends of the rotor shafts 22 are supported by an end support 24, and more particularly by rotatably engaging apertures 25 provided in the end support 24.

In use, the rotary machine 20 can be used in two opposite and inverse configurations. First, the rotors 21 may be driven, e.g. by a combustion process, and may thus transmit rotation, via the transmission arrangement 10, to the drive gear 30. This would be the case if the rotary machine 20 is to be used as an engine or a turbine. Alternatively, the drive gear 30 may be driven and may induce rotation, via the transmission arrangement 10, of the two rotors 21. This would for instance be the case where the rotary machine 20 is to be used as a compressor or a pump.

As is disclosed in the prior PCT application, the two rotors 21 rotate in opposite directions and at constantly varying angular speeds relative to one another. A customized transmission arrangement 10 is therefore required to ensure constant angular speed and unidirectional rotation of a drive gear 30.

Likewise, in order for the rotation of a drive gear 30 to be converted to opposite rotation of the rotors at different angular speeds, a customized transmission arrangement 10 is required.

The transmission arrangement 10 utilised to give effect to this requirement will now be described in more detail. The transmission arrangement 10 includes two contoured discs 11 which are mounted on the rotor shafts 22. The contoured discs 11 rotate together with the rotor shafts 22, and thus the rotors 21. The contoured discs 11 include a plurality of grooves or channels 12 which act as cams, as will be described in more detail herein below.

Follower discs 13, one associated with each contoured disc 11 , is also located on the rotor shafts 22, but is rotatable about the rotor shafts 22. Cam followers 14.1 and 14.2, in the form of pins, extend from the follower discs 13 and are adapted to engage the grooves or channels 12 (acting as cams) in the contoured discs 11. When the contoured discs 11 , and thus the rotors 21 , are rotated, rotation will also be induced in the follower discs 13. The particular shape of the channels 12, and thus the selected cam profile, will ensure that the varying angular speed displacement of the rotors 21 are converted to constant angular speed displacement of the follower discs 13. These follower disks 13 and gears 15 will act as flywheels since they rotate at constant speed.

Each follower disc 13 is furthermore rotationally secured to a gear wheel 15. The gear wheels 15 are also rotatable about the rotor shafts 22, but are rotationally fixed relative to the follower discs 13. The gear wheels 15 will rotate in opposite directions and will also engage one another so as to convert the oppositely directed rotation of the rotors, and thus the follower discs 13, to the same rotational direction.

As has been explained above, the rotation of the two contoured discs 11 will be of variable angular speed nature since they rotate with the shafts 22 and thus with the rotors 21. More particularly, due to the configuration of the rotary machine 20, and specifically the two rotors 21 , one of the contoured discs 11 will be moving at a lower angular speed when the other contoured disc 11 is moving at a higher angular speed and vice-versa. The transmission arrangement 10 will however ensure that this variable angular speed displacement of the two rotors 21 , and thus the contoured discs 11 , are converted to constant and unidirectional rotation of the drive gear 30.

It will also be appreciated that the transmission arrangement 10 can be used in an opposite configuration, wherein the drive gear 30 is driven by an external source and wherein the transmission arrangement 10 is then utilized to induce varying angular speed and oppositely directed rotation of the two rotors 21 , as may be required when using the rotary machine as a pump or a compressor.

The specific design and configuration of the contoured disc 11 is of utmost importance, and one particular design is shown in more detail in figure 6. In this particular embodiment two sets of six channels, 12.1 and 12.5, are provided, which matches two sets of six followers 14.1 and 14.2, or pins, provided on the follower discs 13. Friction between the follower and the contoured disc will be minimized by the use of bearings 16 on the followers.

Each channel 12 can be divided into a first section, 12.1 or 12.6, a second section, 12.2 or 12.7, and a third section, 12.3 or 12.8. In use, torque is induced by the contoured disc 11 onto the follower discs 13, or wee-versa depending on the mode of operation, when the follower 14 extending from the follower discs 13 is located in the first section of the channel 12. The second section of the channel 12 acts as a release or a turning section, and in the third section of the channel, the follower, 14.1 or 14.2, is merely allowed to be displaced from the contoured disc 11 whilst the other follower disc 13 is driven by its matching contoured disc 11. The particular profile of the channels 12 result in constant-speed displacement of the follower disc 13. As shown in figure 6, the followers or pins are displaced in the directions of arrows A, B and C. Arrows A and C shows the path of the longer followers and form part of the same channel set (i.e. no.12.2). Arrow B indicates the path of a shorter follower or pin, and is in a different channel set than the two adjacently located and partially overlapping grooves shown by A and C. The design of the contoured disc 11 , and in particular the channels, is such that one long follower 14.1 will leave the groove depicted by Arrow C just as the next long

follower 14.1 enters the next groove of the same set (i.e. the groove indicated by Arrow A).

In this embodiment the first set of channels 12.1 (Arrows A and C) is generally V-shaped, whereas the second set of channels 12.4 (Arrow B) is generally U- shaped. There is also provided for the one set of channels 12.1 (Arrows A and C) to be deeper than the other set of channels 12.5 (Arrow B), and thus for the one set of followers to extend further from the follower disc than the other set of followers.

However, the contours 12 of the contoured discs 11 could also be defined by the outer periphery of each contoured disc 11 and each follower disc 13, as shown in a second embodiment of the transmission arrangement, shown in figures 8 to 11. In this embodiment, the followers 14, now located on both the follower discs 13 and on the contoured discs 11 engage the outer periphery of the contoured disc 11 and the follower disc 13. In figures 8 to 11 , discs represent the gear wheels 15, but it is to be understood that these are gear wheels similar to the gear wheel 15 of the first embodiment of the invention.

The inventor is of the opinion that the transmission arrangement 10 described herein is a novel transmission arrangement which can be utilised to drive a drive shaft and alternatively to drive the rotors of the rotary machine, and in particular enables constant rotational displacement to be converted to oppositely directed and varying angular speed displacement of two rotors

rotating about a parallel axis, and vice-versa. Furthermore, the rotation of one contoured disc is transmitted to the other contoured disc via the follower disc arrangement rotating at constant speed and not the same speed as the contoured discs. The expected result is mathematically illustrated by the graph in figure 7, which plots the displacement position of the two rotors against the displacement position of the drive gear or output axle.

It will be appreciated that the above is only one embodiment of the invention, and that there may be many variations without departing from the spirit and/or the scope of the appended claims. For example, the rotors could have 5 vanes instead of 6, which would means that the contoured discs would also have 5 contours instead of 6. Furthermore, the two rotor shafts could be directly coupled to the output shaft if a chain and gear arrangement is used. This could prevent "backlash" that could be present in the present embodiments.