BACKGROUND TO THE INVENTION

THIS invention relates to a rotary vane device and more particularly but not exclusively, to a rotary vane engine or pump. The invention also relates to a rotor assembly suitable for use in such a rotary vane device.

Rotary engines and pumps are well known in the art. One common embodiment of this technology utilizes a rotor having a plurality of vanes extending radially outwardly therefrom, with the vanes being radially displaceable relative to the rotor. More particularly, the vanes on a rotary vane device travel in and out of the rotor as they move around the interior wails of the housing of the rotor. Centrifugal force or springs are used to hold the vanes against the outer wall. In their extended state, these vanes adjust to the housing's (or cylinder's) profile as they are driven by the rotor. The displaceable vanes, used in combination with a rotor mounted offset relative to a cylindrical housing in which it is located, result in the formation of varying volume chambers between the rotor and the housing, with the volume of a chamber changing as the rotor rotates inside the housing. Common uses for a rotary vane pump include hydraulic fluid compression and compressed air pumps in aircraft or trucks. Small rotary vane pumps can be used for drink dispensers, medical dispensing pumps, water pumps on marine engines, compressed air drills and many other applications. The materials used to make the pump and vanes can be modified for high- temperature industrial applications such as furnace air injection or engine turbocharging. Rotary vane pumps also work well as vacuum pumps for example in aircraft applications, laboratory vacuum systems, medical applications and also to evacuate and recover refrigerants from air conditioning systems. Rotary vane engines are also known in the art.

A good seal is required between the end of a displaceable vane and the housing surface in order to maintain efficiency of the rotary vane device. Centrifugal forces exerted on the vanes inherently contribute to ensure that a good and dynamic seal is formed between the end of a vane and an inner surface of a rotor housing. However, in some cases centrifugal forces are not sufficient, and it has accordingly been proposed to use springs to augment the outwardly directed bias of the rotating vanes. Springs, however, wear over time which adversely affects the performance and reliability of a rotary vane device incorporating spring driven vanes. In addition, it also complicates the maintenance of the device.

It is accordingly an object of the invention to provide a rotary device that will, at least partially, alleviate the above disadvantages.

It is also an object of the invention to provide a rotary device which will be a useful alternative to existing rotary devices.

It is a still further object of the invention to provide a rotor for used in a rotary device that will, at least partially, alleviate the above disadvantages. It is another object of the invention to provide a rotor for a rotary device which will be a useful alternative to existing rotors.

SUMMARY OF THE INVENTION

According to the invention there is provided a rotor, suitable for use in a rotary device, the rotor including:

a cylindrical rotor body including a plurality of longitudinally extending receiving slots; and

and a plurality of vanes, with each vane s!idingly beatable inside a receiving slot;

characterized in that the vanes are biased away from the cylindrical rotor by way of magnet arrangements.

There is provided for at least one vane magnet to be located towards an operatively inner end zone of each vane.

Preferably, the at least one vane magnet is located in at least one of the sides of the operatively inner end zone, in order for the vane magnet to face a side of the receiving slot. Vane magnets may also be located on both sides of the operatively inner end zone of the vane, in order for the vane magnets to face both sides of the receiving slot.

There is provided for at least one rotor magnet to be located inside the receiving slot. Preferably, the at least one rotor magnet is located towards an operativeiy outer end of the receiving slot, away from the base of the receiving slot.

There is provided for the poles of the at least one vane magnet and the at least one rotor magnet to be configured to be opposite to one another in order for the at least one vane magnet and the at least one rotor magnet to attract one another, so that the rotor magnet effectively pulls the vane magnet, and hence the vane, from the receiving slot to a position where the vane extends from the receiving slot.

Alternatively, the vane magnet may be located in an end face of the operativeiy inner end zone of the vane, and a rotor magnet may be provided in the rotor body towards the base of each receiving slot, with the polarity of the vane and rotor magnets being configured for the magnets to oppose one another, in order to bias the vanes away from the rotor.

More than one magnet may be provided in each vane, and more than one magnet may also be provided in each side or base of the receiving slot.

There is also provided for the receiving slots to be radially offset relative to a central axis of the rotor body.

There is provided for an outer end of each vane to be of a tapered or beveled configuration in order to form a sealing face that abuts a rotor housing in use.

According to a further aspect of the invention there is provided a rotary device including the rotor as described above. BRIEF DESCRIPTION OF THE DRAWINGS

Two embodiments of the invention are described by way of non-limiting examples, and with reference to the accompanying drawings in which: is an exploded perspective view of a rotor assembly for use in a rotary device in accordance with a first embodiment of the invention; is a perspective view of the assembled rotor assembly of Figure 1 located inside a rotor housing so as to form the rotary device; and is a cross-sectional end view of the rotary device of Figure 2; is an exploded perspective view of a rotor assembly for use in a rotary device in accordance with a second embodiment of the invention;

Figure 5 is a perspective view of the assembled rotor assembly of

Figure 4 located inside a rotor housing so as to form the rotary device; and

Figure 6 is a cross-sectional end view of the rotary device of Figure 5.

DETAILED DESCRIPTION OF INVENTION

Referring to the drawings, in which like numerals indicate like features, non- limiting examples of rotary devices in accordance with the invention is generally indicated by reference numeral 10,

In both embodiments (Figure 1 to 6) the rotary device 10 comprises a rotor assembly 11 that is locatable inside a complementary rotor housing 12 so as to define a part of a rotary device. The detail design of the components may vary, and are not of importance because the detail design of the rotary device will be dictated by the specific purpose for which the device will be utilized. The principles underlying this invention may for example find application in rotary pumps, rotary compressors and rotary engines, provided the particular rotary device does make use of radially dispiaceable vanes.

The rotor 11 comprises a rotor body 20 and a plurality of vanes 30 that displaceably extends from the rotor body. The rotor body 20 is of a cylindrical configuration, and is circular in cross section. The length and diameter of the body will depend on the cylinder capacity that is required for a particular application. A plurality of receiving slots 22 are provided in the body, and extends parallel to a longitudinal axis of the cylindrical body, in the embodiment shown in Figure 1 to 3 the receiving siots 22 are at least partially offset relative to the center of the cylindrical body. In the embodiment shown in Figures 4 to 6 the receiving slots 22 extend radially outwardly from a center of the rotor body 20.

In the embodiment shown in Figure 1 to 3, cylindrical apertures are provided in the body 20 at the base of the receiving slot 22, and rotor magnets 23 are located in such apertures. The number of rotor magnets will depend on the iength of the rotor, and thus the length of the vanes 30, as well as on the biasing force that is required. Each vane 30 is in the form of a block of material 31 configured and dimensioned to fit inside a receiving slot 22. Vane magnets 33 are provided at the end zone of the vane that will in use be located inside the receiving slot 22, and are more particularly located in the end face of the end zone. The vane magnets 33 and the rotor magnets 23 are configured to oppose one another, in order for the vanes to be biased away from the rotor body. An opposing end 32 of the vane 30 is at least partially arcuate or tapered and in use abuts, and forms a seal against, an inner wail 12.1 of 1the rotor housing.

The advantage of this configuration is that the magnets provide a biasing force, functionally similar to that usually provided by springs, but without having the additional complexity and reliability issues associated with springs. The magnet configuration will therefore ensure that the vanes are continuously urged towards the rotor housing so as to ensure that a continuous and efficient seal is formed between the rotor and the stator.

In the embodiment shown in Figures 4 to 6, apertures 22.2 are provided in the body 20, and more particularly in the sides 22.1 of the receiving slots 22. The apertures are located towards the operatively outer end of the receiving slots 22. Rotor magnets 23 are located in the apertures 22.2. The apertures 22.2 may be in the form of elongate slots, but this is merely a manufacturing issue, and the rotor magnets 23 will be located at ends of the slots proximate the operatively outer end of the receiving slot 22. The number of rotor magnets 23 will depend on the Iength of the rotor, and thus the Iength of the vanes 30, as well as on the biasing force that is required. Each vane 30 is in the form of a block of material configured and dimensioned to fit inside a receiving slot 22. Vane magnets 33 are provided at the end zone 34 of the vane 30 that will in use be located inside the receiving slot 22. However, in this case the vane magnets 33 are not located in the end of the end zone 34, but rather in opposite sides of the end zone 34 in order for the vane magnets 33 to face the sides of the receiving slot 22 and not the base of the receiving slots, as was the case for the first embodiment.

In this embodiment the vane magnets 33 and the rotor magnets 23 are configured to attract one another. Due to the fact that the vane magnets 33 are located towards the inner end zone 34 of the vanes, and the rotor magnets 23 are located towards the outer ends of the receiving slots 22, the rotor magnets 23 wili attract the vane magnets 33, and will therefore exert an outwardly directed pulling force on the vane 30, i.e from the receiving slot 22 to a position where the vanes extend from the receiving slots 22. The vanes 30 will therefore stil! be biased away from the rotor body up to a point where the rotor magnets 23 and the vane magnets 33 are aligned. This is, however, not a configuration which will necessarily be achieved during normal operation of the rotor assembly, because the maximum outwardly displaced positions of the vanes wili generally be a position where the vane magnets 33 are still located inboard of the rotor magnets 23. An opposing end 32 of the vane 30 is at least partially arcuate or tapered and in use abuts, and forms a seal against, an inner wall 12.1 of the rotor housing.

The embodiment of Figures 4 to 6 result in additional advantages over the prior art, and also over the embodiment of Figures 1 to 3. First of all, the externally directed bias increases as the vane is displaced from the receiving slot, whereas in the first embodiment, the externally directed bias decrease the more the vane is displaced from the slot. This is because, in the second embodiment, the strongest magnetic force (in the form of attraction) is achieved when the vane is in the extended position, whereas in the first embodiment the strongest magnetic force (in the form of repulsion) is achieved when the vane is in the retracted position. This becomes evident when the distances between the magnets in the maximum displaced position (Y) and the distance between the magnets in the retracted position (X) is considered, with X being significantly larger than Y. The largest force will be exerted when this distance is the smallest. This is particularly beneficial in that the sealing force exerted by the vane of the second embodiment on the housing will actually increase as the interna! chamber of the housing wears away. The inherent displacement limit will be when the rotor and magnets are aligned (as indicated above) but the rotor assembly will be designed in order for this position not to be fully achieved in use.

An additional advantage of the second embodiment is that the rotor and stator magnets will never be at risk of abutting one another. Hard impact between the magnets may damage the magnets, and is therefore not desirable.

!t wiii 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 invention.