MAGNETIC DRIVE FLUID PUMP

FIELD OF THE INVENTION

This invention is directed to an apparatus which may be in the form of a pump or compressor and which can function to compress or to accelerate a fluid such as air or a liquid. The invention may also comprise an electric motor and an electric generator. The apparatus includes at least two compressing members which may be in the form of pistons. Each piston can move along its stroke, but one piston remains stationary while the other piston moves to compress the fluid against the stationary piston. Thereafter, the stationary piston becomes the moving piston and the moving piston becomes the stationary piston. This procedure is repeated while the apparatus is in use. The apparatus is not limited to pumping or compressing air and may find applications with gas mixes, mixtures of gas and liquid, liquid alone, flowable powders and the like.

BACKGROUND ART

Pumps and compressors which use moving pistons are well known in the art. Typically, the piston is connected to a crank. The piston reciprocates in a cylinder and the reciprocating action results in pumping fluid which passes into the cylinder. The pump is typically electrically powered, powered by an internal combustion motor and the like. One disadvantage with this type of pump is that pumping occurs only when the piston is in the compression stroke. When the piston is in the drawdown stroke, no pumping occurs as the drawdown stroke is required to suck additional fluid into the cylinder or housing. Therefore, half the action of the piston does not contribute to the pumping action. One type of conventional pump does fill and discharge simultaneously but it requires reciprocation of the piston. Another disadvantage with existing piston pumps is that the piston has a short stroke and the result is increased wear and tear of the pump. Moreover, these types of pumps generally suffer from excessive noise levels making them unsuitable in many applications.

A conventional piston in a cylinder has about a 1 :1 bore to stroke ratio. For instance, if the bore has a diameter of 60 mm, the piston stroke is also approximately 60 mm. An advantage of the apparatus of the present invention is that the "piston" to "bore" ratio can be 7:1 , 10:1 , or even larger. Thus, the apparatus can have approximately 10 times the stroke of a conventional piston in a cylinder. Another advantage is that the next charge of fluid is sucked into the apparatus simultaneously to fluid being discharged. This allows the apparatus to work at lower speeds, provides lower wear and reduced noise during use of the apparatus.

Conventional electric motors have two or more field windings composed of coils of electricity conducting wire that generate a magnetic field when energized by an electric current flow. Metal used for the wire is usually copper but other metals may also be used such as aluminium. The magnetism is imparted to a large amount of iron which by its shape ducts the magnetic field into a north and a south pole positioned each side of a rotating member or rotor which chases the alternating polarity of the stator to produce rotation of the rotor. The rotors extension is also the motor shaft from which useful work can be derived such as driving a pump and the like. Conventional electricity generators operate by causing magnets to pass close by electricity conducting wires wound in a coil fashion. They also employ large amounts of iron to duct the magnetism of the magnets to the wire coils. One advantage of the present invention is that in some versions the large amount of iron cooperating with the wire coil in a conventional electric motor or generator is eliminated. Another advantage is that the shaft of a conventional motor or generator is not required.

OBJECT OF THE INVENTION

It is an object of the invention to provide an apparatus which can compress a fluid and which may overcome at least some of the above-mentioned disadvantages.

Another object of the invention may be to provide an electric motor

in a single device that employs pistons instead of the usual rotor of most other electric motors.

Another object of the invention may be to provide an electricity generator that employs pistons instead of the usual rotor of most other electricity generators.

Another object of the invention may be to provide a motor and pump that does not have the rotating shaft of a conventional motor.

Another object of the invention may be to provide a turbine that has a positive displacement.

In one form, the invention resides in an apparatus for pumping or compressing a fluid, the apparatus comprising: a. a housing which has an annular bore, b. at least one inlet and at least one outlet communicating with the bore, c. a first piston, d. a second piston, each said piston adapted for movement relative to the bore, e. a magnetic drive means to drive one said piston relative to the bore, f. a magnetic or mechanical locking means to lock the other said piston against movement entirely along the bore.

Other forms of the invention may comprise other combinations of features.

It is an object of this present invention to provide a pump or electric motor that is driven magnetically or electromagnetically and that can also be driven in a reverse manner similar to the way that some types of electric motors can become an electricity generator if their shaft is rotated mechanically.

Any piston sealing rings may entirely encircle the pistons. By

having the pistons moved and the stationary piston held magnetically no mechanical locking pins or any other mechanical means may be required although in one version the piston arresting or locking mechanism may be mechanical and activated mechanically or magnetically.

The present invention teaches a compressor, a pump and a motor including an electric motor. It also teaches an electric generator when a force is applied to the pistons to cause them to travel along the bore. One means is based on the working of the commonly known solenoid. It works on the principle that electricity flowing through a conducting wire generates a magnetic field. If many turns of such a wire are wrapped around in a coil fashion the magnetic field strength will be increased according to the number of turns. The wire coil is wrapped around a non conducting shell in the case of the solenoid

The magnetic field will result whether the non conductive shell is there or not but the shell is required to guide the iron core and to prevent it touching the wires.

The coil and the iron collectively become a magnet as long as the electric current is flowing through the wire. When the current is switched off the magnetism ceases.

The electric current may be direct current (DC) or alternating current (AC) as long as the core is of a magnetic conductive material. Iron cores are usually used in solenoids. It does not matter which direction the current is flowing in this case as the iron will take on the same magnetic polarity of the coil.

In the case of the present invention a plurality of these same wire coils, called field windings or stators, are wrapped around a non conductive shell that is extended around in an annular path to form a hollow torus.

Once the piston is drawn into any field coil that coil can be switched off and the next field coil switched on and so on until the piston is

transported the full length of the curved bore.

To this point it has been shown that the present invention employs a progressively moving magnetic field to induce movement of a piston which can move toward that magnetic field or be pushed away from a magnetic field.

The magnetic field is not moving literally but each coil is progressively generating a brief magnetic field, thus attracting the piston to it. It is then switched off and the next coil is energized and so on. The effect is that of a magnetic field moving along the inside of the internal chamber or bore of the hollow torus and attracting the piston after it.

If utilising direct current electricity and if iron is used in the pistons the changeover of the piston may be achieved by energizing the first or number one coil followed very quickly by energising the brake coil to be of opposite polarity. (The brake coil is considered to be the last coil in the 360 degree circuit and the first coil seen in the figures to the right of the brake coil is considered to be the first coil in the circuit). The pistons would then be of opposite polarity meaning their north poles would face each other or their south poles would face each other and so would repel each other. The brake coil would remain energized to hold the piston or preferably switched off after a mechanical latch engaged the piston to prevent its movement. Meanwhile the traveling piston has been progressively transported through the rest of the coils.

If alternating current is utilised to activate the coils the frequency of the alternation of electric current direction change must be much faster than the frequency that any piston passes through each coil. This is because the coil ideally should be regarded as a magnet that is either on or off and that can only be so if the switching frequency is high relative to the piston speed. For example, if the frequency of the alternating current was 60 cycles (60 hertz) then the piston speed would need to be far lower than a speed that would cause it to pass through 60 coils each second. That is because it takes some time for the collapse of the magnetic field in the iron piston whereas the magnetic field

of the coil is forced to change polarity rapidly by the reversal of the current direction that is characteristic of alternating current. Therefore the residual magnetism in the iron piston may run into a magnetic field of a coil that may repel it. If 10 coils are employed around the torus the piston would travel around the torus 6 times per second or 360 revolutions per minute (360rpm). That is not a high rpm. Therefore the delivery of alternating current from the electricity company at 50 or 60 cycles per second may be unsuitable for higher rpm. Otherwise a suitable way to utilize AC electricity may be employ electronic controllers that deliver far higher frequencies which may be more suitable.

Alternating current energizing of the coils causes them to have a rapidly alternating polarity. As long as iron is used and the frequency is high enough this is suitable to keep the iron attracted to the inside of the coil. In this case the piston changeover may be achieved by energizing the number one coil before energizing the brake coil to attract the stationary piston forward before the traveling piston arrives to be trapped by the brake coil. In this case the newly traveling piston speeds forward through the coils while the newly arrived stationary piston remains trapped by the magnetic field of the brake coil.

There is no limitation on how electricity may be delivered to the coils of the invention. Present or future means may enable mains electric current to be utilised by the invention. The discussion of various ways to electrically energize the coils is to indicate a further advantage of the invention in so far as it may be able to utilize a number of different sources of electric current for different applications. For example where electricity is only available from wind generators, solar arrays or water turbine generators which charge batteries then direct current (DC) may be utilized or DC may be processed by an electronic controller to be delivered as pulse width modulation (PWM) current. Automotive applications have alternator electricity or battery DC available and so on.

There is no limitation on the number of field coils that may be practically employed or any limitations on the timing or field strength of any.

The invention has been described as employing magnetic pistons. In versions where iron or any other material able to be magnetized is employed within the pistons, it is to be understood that the description is still valid and true. That is because when the field coils are energized the iron in the nearby piston is caused to become a magnet due to induction and takes on the same polarity as that coil. Therefore the invention teaches that the pistons contain or are magnets and it does not matter if those magnets are permanent or are induced to be magnets momentarily and intermittently.

So far one way to perform the invention has been described. It is to create an effect similar to a solenoid but with curved pistons and bore and to switch the field coils on and off progressively around the bore. This way may use AC or DC and the electric current direction is not important

A second version can now be introduced. The pistons are or have embedded in them strong permanent magnets. Some of the rare earth magnets are ideal for this however any permanent magnet may be used. Examples of strong rare earth magnets are Samarium cobalt and Neodymium.

In that case the pistons are already magnets and do not rely only on induction of magnetism as with the first version of the present invention. This has advantages as there may not be the same efficiency losses. In this version, DC electric current may be employed to cause the wire coils or field windings (stators) to become magnets. The stators in front of the piston are the leading stators and those behind are the following stators. In this version the stators (field windings) in front and behind the piston may be energized and so the piston may be pulled by one stator in front and pushed by one stator behind simultaneously. If two or more leading, adjacent stators, are energized simultaneously with the same polarity they will function as one magnet. The same applies to the following stators. The leading stators have the same polarity as the magnetic piston and so attract it. The following stators will have the opposite polarity to the piston and so repel it. In this way the piston may be pulled and pushed simultaneously with great force. As it takes a few hundredths of a second for the magnetic field to build and

a similar time to collapse it may be necessary to reverse the current flow to a coil during or after the piston is passing through it to force the collapse of the field. This may be important when the magnets in each piston are of opposite polarity. The current direction reversal may prevent that coils magnetic field retarding the progress of the piston and may propel that piston from behind. It also may force the field to collapse thus leaving no existing residual magnetic field to oppose the next piston or if any residual field has not yet collapsed that field will then be of the correct polarity to attract the next approaching piston.

Any combination of leading and following stators may be activated.

The magnets in each piston may be of the opposite polarity. The north poles of magnets repel each other as do the south poles and one version of the invention may use this phenomenon to assist the piston changeover.

The switching of current flow from one field winding to another may be accomplished by commutation or electronically and does not need to be described here as electric current control and switching is very common in modern solid state electronics.

This need for control for similar or different reasons is the same as with any conventional electric motor or electric apparatus.

There may be other ways to magnetically transport the pistons along the annular bore that may be equally effective or more so than the ones described here. Permanent magnets may be passed along the outside of the hollow torus to drag the internal pistons along the bore. This would be where a rotating shaft was available. Also other means may be developed in the future.

Therefore the present invention resides in a pump and motor that is run magnetically, the means described here being only some of a larger number of magnetic possibilities to perform the invention.

The invention teaches the need for one of the pistons to remain substantially still between the inlet and outlet ports. Therefore one of the stators (field windings) is placed between the ports and it may remain energized most of the time to hold the stationary piston firmly in place resisting the force of the fluid being pushed in front of the moving piston. This stator may be of a different specification to the other stators. It may be called the brake coil. It may have different wire diameter and a different number of turns or have a different voltage passed through it as it must possess approximately the same or more field strength than the field strength that is transporting the moving piston along the bore moment to moment. The field strength of both the brake coil and each of the coils transporting the moving piston must generate a force that overcomes the downstream resistance to the fluid flow. That resistance could be a result of any number of factors. For example the pump may be compressing gases such as air or may be pumping water up a hill. Any ducting also offers a resistance due to friction.

The resistance due to the pumps duty or load has to be overcome by the force of the pushing piston. It can readily be seen why the stationary piston must be held in place by a force at least the same as the force that moves the traveling piston.

Alternatively the stationary piston may be arrested and held stationary by a mechanical means that may be activated by a cam or trip or may be activated magnetically. The advantage in the case of a magnetic arrest of the piston and then holding it mechanically is that only a brief electrical energy input is required. Once activated no more energy is required to hold the stationary piston in place. Releasing and repelling the stationary piston forward also only requires the same brief electrical energy input into the brake coil because the braking of a piston and releasing another are the same event. Thus in that case the brake coil remains switched off most of the time.

The present invention may reduce wear substantially by the effect of

the magnetic field pulling the pistons around a circular pathway. The effect may also be enhanced by the fact that the piston may have a geometry which causes the more medial part of the piston to be closest to the magnetic field in front. This may cause a pitching moment advantageous at higher piston speeds.

As described, one or more stators in front and behind the piston may be energized. This may be advantageous for keeping the pitch ideal and for the reduction of centripetal force. For example, if it is desired to activate four stators simultaneously, three may be activated in front of the piston and one behind it. Other combinations may be advantageous.

With varying load and flow requirements the invention may have the voltage increased or decreased, the number of field windings activated at any time increased or decreased, or a combination of both.

It is important to prevent the pistons colliding during changeover. This may be accomplished by having the permanent magnets in the pistons have their same poles face each other. When the moving piston approaches the stationary piston with its north pole facing the north pole of the stationary piston the two will repel each other. The same occurs when the two south poles face each other. After changeover, the stationary piston becomes the moving piston and its south pole then approaches the now stationary pistons south pole. In this way the two pistons always repel each other during the changeover. This substantially eliminates the changeover as a potential source of noise and shock. It also allows a momentum transfer between the pistons.

Momentum transfer is important in some versions this invention. Simultaneously to the momentum transfer the brake coil is activated to become of the opposite polarity to the magnetic piston that it was holding or had been arrested by it. This newly generated opposite polarity of the coil to the stationary piston then repels that piston forward (from left to right as in the Figures) and simultaneously attracts the approaching piston and if the brake coil is

kept activated for a short while it arrests the moving piston like a brake. When this method is employed the field windings must be able to be energized with the opposite polarity every second circuit for each piston. That may be performed by commutation or by solid state electronics. This is because every second circuit the traveling piston is of the opposite polarity to the piston of the preceding circuit. A mechanical latch may be employed to hold the stationary piston in place. The magnetic field of the brake coil substantially arrests the piston first and then the latch engages the piston. The latch may be activated mechanically only or magnetically only or by a combination of mechanical and magnetic means. The magnetic means may be permanent magnetic means or electromagnetic means. The mechanical latch would ideally be substantially disengaged from the piston before activation of the brake coil to release and repel forward the piston. In this way the brake coil may be only energized very briefly to effect the changeover but need not be held on which can result in overheating of the coil. Other means of arresting the piston may be employed.

Thus the momentum transfer between the pistons and the substantially simultaneous activation of the brake coil cooperate to substantially achieve a successful piston changeover.

This present invention is meant to also function as an electricity generator. The principle is similar to how some electric motors are able to also be a generator if the shaft is rotated mechanically.

The present invention is a generator of electric current if the pistons are forced along the bore through the field windings. A typical conventional generator may have 2 or more field windings that the permanent magnets pass closely by during rotation of the rotor. If a 2 pole generator is rotated by a large, slowly rotating shaft such as would be the case with a large wind turbine the magnets may pass the field pole shoes too infrequently to give much power or efficiency. In that case a gearbox must be utilized to increase the RPM of the generators rotor. If the present invention is utilized as a generator having (for example) 10 field windings that are closely spaced around the torus then it may

only need to have the magnetic piston travel at one fifth the RPM of the conventional generator to generate approximately the same amount of current. The advantage is that no gearbox is required.

To operate as a generator any source of force may be utilized to push the pistons along the inside of the bore. Falling water, possessing both static and dynamic pressure, may enter the inlet port of the present invention forcing the magnetic pistons along the bore and then exit from the exhaust port. In that case two or more pistons may be inside the torus even though there may be only one inlet and one outlet port and it must be an even number of pistons to ensure that all oppose each other magnetically because if some adjacent pistons were the same polarity they would stick together to become one long magnet. This fluid flow drives the pistons along the bore through the field windings. Oil may also drive the pistons around. Any gas or gas mixture including combusting gases may push the pistons. The combustion process may take place external to the invention or may take place internally between the pistons. Steam may drive the pistons. In this case the stationary piston would be locked in place to prevent movement in either direction until changeover.

A source of accelerated oil may be from any suitable pump driven by any power source including a wind turbine. This accelerated oil or other fluid in turn pushes the magnetic pistons through the field windings to generate a current flow.

The oil or any other fluid may be drawn from and returned to a fluid reservoir that may contain a filter and the fluid circulating system may be closed. The closed system may be ventilated to atmosphere if the fluid employed is a liquid. In yet another variation of the invention the stationary piston may be locked to prevent movement in either direction relative to the bore and combustion of any suitable fuel initiated between the pistons. The expanding combustion gases drive the magnetic piston along the bore to generate an electric current. In that case a valve would keep the inlet port closed during the combustion process. It is understood that magnets may lose strength if temperatures are too high, so

the magnets would be encased in a heat resistant material and a cooling means applied to the whole apparatus.

Any number of piston pairs and ports are envisaged.

Generating an electric current requires considerable force. That is true for conventional generators as well as the present invention. The reason is that there is a resistance of the free electrons in the wire of the coil to being accelerated to flow along the wire and there is also the resistance to the current flow provided by the electrical device or appliance downstream. For example an electric power saw may be cutting wood. When it is under load and powered by a nearby small electric generator the generator can easily be heard to drop in speed and with some generators to almost immediately then increase rpm as its speed governor causes more fuel to be fed into the engine to overcome the resistance.

When the present invention is employed as a generator the pressure of the incoming fluid must be high enough to overcome the total resistance of the wire of the coil, the wire to the downstream device to be driven and the resistance that device provides. In this case the stationary piston must be locked in place or it may not resist the pressure behind it. However in another case the downstream load may be small and in that case there may be no need to have any of multiple pistons stationary at any time for the following reason. As the coils, wires and downstream devices oppose the forward movement of the magnetic pistons there builds up a pressure in the fluid between the back of the moving piston and the source of the fluid entering the inlet port. Therefore the pressure of the fluid entering the inlet port is higher than the pressure of the fluid leaving the outlet port. If the inlet and outlet ports are suitably configured geometrically the outlet fluid pressure cannot be as high as the inlet fluid pressure and so cannot substantially re-circulate and so the fluid passes out of the apparatus without the need for a stationary piston to separate the ports. This situation would only occur where the load is light and the available pressures, both static and dynamic, of the entering fluid, are moderately high. This case may only

apply when the driving fluid is a liquid.

The invention is suited for a wide variety of applications. As it may use multiple piston rings for good sealing and has a large swept volume due to the very long stroke, it may be used as a compressor including for refrigerators or air conditioners. It may also be used as a liquid pump including a water pump. It may be used as a supercharger for automotive applications. It may be used as a generator of electricity. It may be used as a positive displacement turbine, its pistons driven around by water, air, oil, combusting gasses, steam or any suitable fluid. In this last case it is functioning as a turbine and generator simultaneously as the magnetic pistons are pushed through the field windings to generate electric current. Otherwise when a current is forced through the field windings to induce the magnetism to attract and transport the pistons it is then functioning as an electric motor and a pump simultaneously.

The apparatus may have a substantially circular configuration when viewed in plan. One advantage of the apparatus is that each piston moves along a generally circular pathway as opposed to a reciprocating pathway. This allows the stroke length to be greatly increased relative to reciprocating pistons. In turn, this can result in less wear on the apparatus, less noise during operation, a large volume flow and it is envisaged that many of the components of the apparatus including the pistons can be manufactured from plastics material. The apparatus may also be made of any material, including metal, which may need to be lubricated with any lubricant including oil. In that case a non magnetic metal would be utilized for the chamber housing. There need be no limitation on the length of the chamber. The apparatus contains a housing. The housing may comprise two-part housing or a multiple part housing which are attached together. Typically, the housing comprises a two-part housing consisting of an upper and a lower part which are fastened together typically via separate fasteners such as screws, bolts and the like. Glue may also be used and a flange at the joints may be included. An O ring may be used to seal the meeting of each shell that forms the torus. Each housing part may resemble a hemisphere when viewed in side elevation. One hemisphere may contain the at least one outlet and one

hemisphere may contain the at least one inlet or each hemisphere may contain both.

The housing contains an annular chamber. Suitably, the chamber is defined at least partially by the inner wall of the housing.

The loop shaped chamber is typically substantially circular when viewed in plan and is also typically circular in cross-section. Therefore, in one form the loop shaped chamber may be in the form of a toroid. The length of the loop shaped chamber (the stroke length) can vary to suit but it is envisaged that a length of 10-200 cm will be suitable in respect of most applications. It should be appreciated that these values are not limiting and could, for certain applications, be exceeded up or down, for instance if employed in the hub of a wind turbine. The cross-section length or diameter of the chamber may vary to suit but it is envisaged that a cross-section length or a diameter of 1-20 cm will be suitable in respect of most applications. Again, no limitation is meant by this range, and the chamber may have a diameter of 1 meter or more.

The housing is provided with at least one inlet and at least one outlet which communicate with the chamber. It is envisaged that more than one inlet may be provided and that more than one outlet may be provided. The size and shape of the or each inlet and the or each outlet may vary and the shape may be circular, oval, rectangular, polygonal, or have an irregular shape. The size of the or each inlet and the or each outlet can vary and can be from a relatively small size (to provide a nozzle effect) to a relatively large size. It is envisaged that the inlet and the outlet may be provided with a valve arrangement to regulate fluid passing into and from the chamber. It is also envisaged that some form of manifold may be provided with the inlet and the outlet and a manifold may find particular suitability if multiple inlet and outlets form part of the apparatus which may be the case if the chamber contains multiple pistons.

As an electric motor and pump the apparatus contains magnetic pistons. Each piston is suitably shaped such that as it passes along the chamber

the piston seals, or at least partially seals, against the chamber wall, or sealing means are provided to create a seal or a partial seal. The pistons may also employ piston sealing rings similar to those on a conventional piston. Typically, the chamber will be circular in cross-section and therefore the piston will typically also be circular in cross-section. If the chamber has a different cross-section configuration, such as oval, it is envisaged that the piston will also have an oval cross-section configuration. The piston will typically have a body provided with a front face, a rear face, and an outer wall. The outer wall typically seals or is closely spaced from the wall of the chamber. The length of the body may vary to suit. For instance the piston may be very short in length. Alternatively, the piston may have a body length which is quite large which means that the piston will have a relatively elongate shape. It is envisaged that the outer wall of the piston will be curved in two directions to enable the piston to travel along the chamber while still maintaining a reasonably good seal between the outer wall of the piston body and the wall of the chamber.

The pistons may have quite irregular shapes. In one embodiment of the invention, each piston has a front wall and a rear wall. The front wall has a concave portion and the rear wall has a convex portion. Alternately the front and rear piston faces may be flat and may meet precisely if they are allowed to touch.

If the traveling piston remains substantially stationary relative to the housing and the chamber rotates it will be necessary to provide some form of drive means to rotate the housing which is the same thing as rotating the chamber. An example of where this may apply is where the apparatus comprises the hub of a wind turbine or fan. In this case the piston is not actually stationary but appears to be in relation to the chamber or bore. The moving piston is held relatively stationary to the moving bore by the field windings being activated progressively as the housing rotates. In this case it is the piston that is normally considered to be the stationary piston, held between the ports by the brake coil that is moving in a circle along with the housing, the ports and the turbine blades. However it is stationary relative to the rotating housing as it is locked to it.

The advantage here is that the housing may be manufactured integral with the rotating blades of a wind turbine or another device as the case may be. In the case of the wind turbine or similarly the case of a fan the air may be conveniently pumped directly into the hollow blades of the wind turbine or fan. This gives an advantage when applying a principle called Circulation Control. Circulation Control means controlling the pressure and flow fields around an airfoil. It is usually performed by applying the Coanda Effect, which is where a jet of air is ejected from a slot above the bluff shaped trailing edge of an aeroplane wing, wind turbine blade or fan blade to postpone stall. This greatly increases the lift of the wing or blade. A patent for a Coanda Effect Circulation Control wind turbine is; United States Patent "ADVANCED AERODYNAMIC CONTROL SYSTEM FOR A HIGH OUTPUT WIND TURBINE", US patent number US 6,940,185 B2. The application of Circulation Control to wings or turbine blades usually involves ducting of conventional compressor air through long, convoluted plumbing to the inside of the hollow blades with the consequence of efficiency loss. In some cases centrifugal air blowers are employed. These sources of air are relatively inefficient for slot blowing. In this case of applying the present invention to be or be placed adjacent to a wind turbine hub or for any other application, the traveling or compressing piston may be caused to travel faster than the rotational speed of the housing, turbine or fan blades by more rapid switching of the field windings. This is the equivalent of a gearing effect which may be advantageous in some applications.

In the embodiments, the apparatus is generally described employing a single pair of pistons and ports. However multiple pairs of pistons and ports may be employed. In the case of applying the invention as, or adjacent to, a wind turbine or fan hub, if the turbine or fan possessed 3 blades then the invention may incorporate 3 piston pairs and ports so that each outlet port may direct the air into a hollow blade. Alternatively in a version of the invention possessing any number of pistons and ports there may be placed a second chamber outside or adjacent the chamber containing the pistons to receive the discharged air which is then forced into the hollow blades.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described with reference to the following figures in which:

Figure 1. Illustrates the toroidal housing of the apparatus, and the removable section containing the inlet and outlet ports.

Figure 2. Illustrates the pistons of the apparatus.

Figure 3. Illustrates the short section containing the said inlet and outlet ports of the apparatus of Figure 1.

Figure 4. Illustrates the toroidal housing of the apparatus with a plurality of insulating rings that separate the electromagnetic coils.

Figure 5. Illustrates the upper shell 18 and the lower shell 19 of the housing 11 of the apparatus of Figure. Figure 6. Illustrates the bottom shell 19 of the housing 11 of the apparatus of figures 1 , 4 and 5 with the pistons of figure 2 contained inside.

Figure 7. Illustrates the modified pistons of Figure 2. One piston contains a recess to accommodate a piston sealing ring. The other piston illustrates the piston ring in place. Figure 8. Illustrates a cutaway view of part of bottom shell of Figure 5 that has the joining point and an O ring that acts as a seal.

Figure 9. Illustrates a solenoid and pin that engages the front of the stationary piston.

Figure 10. Illustrates the solenoid and pin of Figure 9 from a different perspective.

BEST MODE

Referring to the figures there is illustrated an apparatus 10 which can function as a pump or compressor to pump gases, liquids, flowable powders, mixtures and the like. Apparatus 10 comprises a housing 11 , which defines a circular internal bore/chamber 12, the housing being provided with at least one inlet 13 and at least one outlet 14, a first piston 15, a second piston 16, a drive

means in the form of a plurality of wire coils 17 each of which generate a magnetic field and a releasable locking means which will be described in greater detail below.

Housing 11 can be made of plastics material, metal, ceramic or any other material and comprises two parts being an upper part 18 and a lower part

19. The two parts are attached together by glue, welding, bolts and the like at 20.

A seal 21 is provided between the two parts to provide a fluid tight housing.

When the two parts are attached together, there is provided an internal ring- shaped recess which forms the loop shaped chamber 12 [which can also be seen as a bore]. The chamber is defined by the inner wall 22 of the upper housing part and inner wall 23 of the lower housing part. The chamber 12 is substantially circular when viewed in plan and is also substantially circular in cross-section. Chamber 12 can also be described as having a toroidal shape. The size (or volume) of chamber 12 will depend on the size of the housing. Typically, chamber 12 will have a diameter of between 10-200 mm and will have a length of between 10-200 centimetres. This can of course vary to suit. The housing may have a wall thickness of between .5-20 mm.

In this particular embodiment, the housing 1 1 is provided with an inlet 13 and an outlet 14. Each of inlet 13 and outlet 14 has a bridge that makes each port appear to be two outlets or inlets. This is because the ports are large enough to cause a piston passing them to become unstable because there would not be enough of the bore wall supporting the piston if this bridge was not provided. For this reason the configuration and the number of the outlet or the inlet holes of any one port may vary.

In this particular embodiment there is a short segment 11A which has an internal wall configuration substantially identical to the remainder of housing 1 1. When housing 1 1 and short segment 1 1A are joined together the full

360 degrees of the toroidal shaped internal passageway is complete. The reason for making housing 11 in these two parts is so that short segment 11A can be removed so that the pistons can be placed within the bore and the insulating rings

and wire coils can be fitted to the housing 11. When housing 11 and short segment 11A are joined the internal walls 22 and 23 are substantially continuous with the very small joints offering substantially no resistance or impediment to the passing pistons.

Pistons 15 and 16 are substantially identical and can be made of plastic material, ceramic, metal and the like. Each piston comprises an outer peripheral wall 25, a front face 26 and a rear face 27. The piston is sized to slide along the chamber and to provide a compressive effect or to otherwise raise the pressure of the fluid in the chamber which means that piston must be in sealing engagement with the chamber wall or closely spaced from the chamber wall to minimise fluid passing between the outer wall of the piston and the wall of the chamber. Therefore, the outer wall of the piston is generally circular. Because the pistons have an appreciable length, the outer wall must also be curved along the direction of travel to accommodate the curvature of the chamber.

The pistons are coupled/released by activation/deactivation of the solenoid 28 activated pin or rod 29.

Referring to the figures there is illustrated a stationary piston 16 and a traveling piston 15 both containing magnets 30. Piston 15, because it contains magnets 30, is drawn around the inside of the bore by the progressively shifting magnetic field of wire coils 17 and thus becomes the traveling piston. In the figures the pistons are to be viewed traveling from left to right thus for a piston to be traveling forward means that the piston is traveling left to right. Stationary piston 16 is held in place by the pin or rod 29. The magnetic field of brake coil 31 arrests the traveling piston but after it is switched off rod 29 holds it substantially in place while the other piston is traveling along the annular bore. When traveling piston 15 approaches the rear of stationary piston 16, the magnets 30 within each piston repel each other and so the pistons do not collide. There is however a momentum transfer with the momentum of traveling piston 15 being transferred to stationary piston 16. This momentum transfer causes traveling piston 15 to be substantially arrested or braked. Simultaneously the momentum has been

transferred to stationary piston 16 which accelerates forward to rapidly assume substantially the speed that traveling piston 15 had before it was arrested by brake coil 31.

During the same very short time frame that the momentum transfer between the pistons is taking place, brake coil 31 is energized and consequently assumes a polarity that is opposite to the polarity of whichever of the pistons that has been the stationary piston. Immediately before this brake coil 31 activation, the pin or rod 29 is withdrawn from in front of the stationary piston. The effect of the activation of brake coil 31 to assume the opposite polarity to that of the polarity of the stationary piston is to, simultaneous to the before mentioned momentum transfer, expel the stationary piston forward and attract the approaching piston. The brake coil 31 is then held on for a short while to fully arrest the newly arrived piston. Thus the momentum transfer between the pistons and the activation of brake coil 31 works together to facilitate the piston changeover. Only when the piston has stopped moving forward does pin 29 engage the front to prevent it moving. By these two effects working together the stationary piston is able to be accelerated rapidly so that the progressively moving magnetic field which draws the piston along the bore does not leave the piston behind.

The chamber 12 is provided with inlet port 13 and outlet port 14 which are positioned at each side of the area where the pistons lock/unlock. Traveling piston 15 almost completes a full circuit through the annular chamber and as it approaches the rear face of stationary piston 16, the gas/liquid is being compressed and passes through an outlet port 14. As the original stationary piston is released and expelled from the area between the ports 13 and 14 it then passes through the area of the inlet port. After passing the inlet port 13 it then sucks more fluid into the chamber 12 through the inlet port 13 which fluid then follows it along the bore 12. Simultaneously, the liquid/fluid in front of the same traveling piston will now be compressed and pushed out of the outlet port 14 as the traveling piston completes its circuit through the chamber. Thus, while the traveling piston is compressing and pushing fluid in front of it, it is also drawing in the next charge which is unlike conventional reciprocating pistons.

Each of the pistons 15 and 16 is provided with a peripheral sealing ring 32 which fits inside a peripheral recess 33 in each piston. Any practical number of piston sealing rings may be employed.

If more than one pair of pistons and ports is employed, they may be spaced at different distances apart to minimise potential stagnation during piston changeover. For example, if three piston pairs are employed, these may be placed at 0°, 110° and 240° which means that there will always be two sections between piston pairs that are pumping while only one of the pairs is experiencing a changeover. The ports may be wider than the piston length or narrower than the piston length.

It should be appreciated that various other changes and modifications can be made to the embodiment described without departing from the spirit and scope of the invention.

Throughout the specification and the claims (if present), unless the context requires otherwise, the term "comprise", or variations such as "comprises" or "comprising", will be understood to apply the inclusion of the stated integer or group of integers but not the exclusion of any other integer or group of integers.

Throughout the specification and claims (if present), unless the context requires otherwise, the term "substantially" or "about" will be understood to not be limited to the value for the range qualified by the terms.

Any embodiment of the invention is meant to be illustrative only and is not meant to be limiting to the invention . Therefore, it should be appreciated that various other changes and modifications can be made to any embodiment described without departing from the spirit and scope of the invention.