Rotary Machine and Combustion Engine

The present invention relates to a rotary machine which can be employed in different applications such as, for example, a combustion engine or compressor. The invention further relates to an assembly of two or more rotary machines and a combustion engine based on the rotary machine. The machine is substantially composed of a helical screw-shaped rotor connected to an outgoing shaft journal, which screw-shaped rotor rotates in a cylindrical housing. The machine is further provided with rotating chamber dividing bodies whose rotation is synchronised with the rotating screw-shaped rotor. The chamber dividing bodies divide the helical screw grooves into chambers whose volume varies with rotation of the screw- shaped rotor.

Various kinds of compressors and combustion engines are known in the prior art. Screw compressors are generally previously known with screw-shaped rotors. Some known solutions are described in EP 0517250, GB 2131877 and GB 923042 where GB 2131877 in particular has features resembling the present invention.

As far as combustion engines in the field of rotary machines are concerned, engines are known according to the so-called Wankel principle where an eccentrically rotating rotor forms chambers in a housing and where gas exchange and combustion take place in one or more of the chambers so formed. It is known, however, that existing combustion engines are not very efficient, having amongst other things large rotating mass, i.e. there is large mass in the rotating parts. The gas exchange in traditional combustion engines, moreover, is often inadequate with the result that the supply of oxygen through supplied air is not necessarily optimal, nor is the removal of burnt gases optimal. In addition the actual power utilisation in a traditional piston engine is far from optimal since a linear motion is created in a piston in a cylinder and this linear motion has to be further transferred to rotating motion which takes place in a sinusoidal transfer where the torque increases from low (approximately zero) to maximum before again decreasing to approximately zero. In addition traditional piston engines are critical with regard to balancing of rotating mass since a continuous transfer takes place in the engine from linear to rotating motion.

It is an object of the present invention to provide a rotary machine which in different applications can be employed both as a compressor and as a combustion engine, where the technical core of the present invention will be included in different embodiments in these applications. The object is further to provide a rotary machine which has better characteristics than previously known solutions. With regard to the special application of the rotary machine according to the present invention as a combustion engine, a number of the above-mentioned drawbacks

involving balancing, gas exchange and power transfer to the outgoing shaft will be improved.

According to the present invention, therefore, a rotary machine is provided substantially comprising a screw shaft with one or more helical screw grooves, which screw shaft is designed at least at one end in the screw shaft's longitudinal direction for connection with an engine or a drive gear. The rotary machine is characterised in that:

- the screw shaft is rotatingly mounted in a housing with an internally cylindrical shape where the housing's internal diameter substantially corresponds to the external diameter of the screw shaft, which housing is substantially sealed at each of the ends of the screw shaft with a through-going opening for the screw shaft's connection with an engine or drive gear and which housing includes bearings for the screw shaft,

- the helically-shaped screw grooves extend in a helical form from one end of the screw shaft to the opposite end of the screw shaft,

- the rotary machine includes one or more rotatingly mounted chamber dividing bodies, each of which chamber dividing bodies is designed as a substantially circular body with a rotation centre, each of which chamber dividing bodies has a number of triangular chamber dividing blades protruding from the centre of the chamber dividing body with the narrowest end at the centre of the chamber dividing body, which chamber dividing blades are mounted at intervals and which chamber dividing bodies are rotatingly mounted at the outer edge of the screw shaft with a rotational axis substantially extending perpendicularly to the screw shaft's rotational axis and where the rotation of each of the chamber dividing bodies is synchronised with the rotation of the screw shaft, with the result that the chamber dividing blades on the chamber dividing bodies project into the helical screw grooves in the screw shaft and follow the screw groove's movement when the screw shaft rotates so that a chamber dividing blade on a chamber dividing body follows a helical groove and divides the helical groove into a chamber on each side of the chamber dividing body on rotation of the screw shaft, which chambers have varying volume when the screw shaft rotates since the total volume of the helical groove is divided in two by the chamber dividing body and as the screw shaft rotates, the volume on each side of the chamber dividing body will be altered between substantially 0 and 100% and the two chambers together form at any time a total volume substantially equal to the volume of the helical screw groove and

- at least one inlet opening is provided in the housing to the interior of the cylindrical housing into the helical screw groove at one end of the cylindrical housing and at least one outlet opening in the housing to the interior of the cylindrical housing into the helical screw groove at one of the ends of the cylindrical housing.

If chamber dividing bodies are provided on opposite sides of the screw shaft's longitudinal direction, these chamber dividing bodies must be contra-rotating.

In different embodiments, the number of helical grooves in the screw shaft may be equal to the number of chamber dividing blades on the chamber dividing body, but it may also be different.

In order to achieve a good seal between the chamber dividing bodies and the helical screw groove so that each helical screw groove is divided into different chambers by the chamber dividing body, the profile of each chamber dividing blade is preferably of a complementary shape to the internal shape of the helical screw groove. The chamber dividing body may be flat on top and slightly conical with curved surfaces on the bottom, with the result that its shape is complementary to the screw groove so that a seal is obtained with the screw groove when a chamber dividing blade moves into the screw groove and follows it while both the screw shaft and the chamber dividing body are rotating. The chamber dividing bodies may have a great many different shapes and in an embodiment may be a flat disc or plate. The chamber dividing bodies may also have a flat top and a curved or pyramidal bottom or they may be more spherical in shape. As long as the chamber dividing body or at least each chamber dividing blade has a shape that is complementary to the interior of the helical groove, the chamber dividing bodies and/or the chamber dividing blades may otherwise be designed in a suitable manner with regard to heat development, pressure ratio, bearings, etc.

The cylindrical housing in which the screw shaft moves has an interior cylindrical shape and the exterior may be of any shape whatever, thereby enabling it to form part of a larger structure. Several rotary machines according to the invention may, of course, be arranged side by side or on top of one another or in some other way. In some embodiments several housings may also be provided, so that two housings also divide a chamber dividing body, i.e. the chamber dividing body protrudes simultaneously into two helical grooves with different chamber dividing blades. In such embodiments the rotation of each screw shaft must be synchronised with one another and with the chamber dividing body.

The screw shaft is suitable for transporting and possibly compressing a fluid such as a liquid or gas. To enable the fluid to be admitted to the helical groove in the rotary machine, an inlet opening is therefore provided through the housing in towards the screw shaft. The inlet opening is preferably located on the side of the screw where the chamber dividing body moves into the helical screw groove, with the result that when the screw and the chamber dividing body rotate, a chamber is created where the volume expands, thereby causing the fluid to be drawn into the chamber. Once the screw shaft has moved so that the chamber dividing blade has followed the helical groove to the end, the valve surface leaves the helical groove and the

chamber is filled with fluid. The next valve surface will then enter the helical groove on continued rotation of the screw shaft and push the fluid content in the helical groove forwards in the groove as the chamber dividing blade moves along the helical groove, forming a chamber that has reducing volume. If the end of the chamber is closed, the chamber dividing blade will compress the fluid against the closed surface. If not, the movement of the chamber dividing body will be able to push the fluid out of the chamber created on the top (the pushing side) of the chamber dividing body. As the screw shaft rotates the chamber with reducing volume will be able to meet an outlet opening from the cylindrical housing and from the helical screw groove, as indicated above and pressurized fluid will flow out. The conclusion of this "emptying" of the chamber occurs when the chamber dividing blade leaves the helical groove and the screw shaft continues to rotate with an empty groove. Whether a compression is to be created or only a "movement" of fluid through the helical groove is therefore determined by the location of an outlet opening and the shape of the outlet opening. If the opening is an elongated slot which is open to the chamber with reducing volume, the fluid in the chamber will be pushed out all the time. If the opening is small in area and located in such a manner in the cylindrical housing that the opening is only uncovered when the chamber dividing body has passed almost through the entire helical groove, a pressure will be created in the chamber by the helical groove that has reducing volume and it will be pressurized fluid that flows out of the outlet opening.

In an embodiment, therefore, a through-flow opening may have a length in the rotational direction corresponding to the whole or parts of the rotational angle over which the helical groove in the screw shaft extends. If the pressurized fluid has to perform several passes through the screw shaft, for example for combustion of pressurized fluid and expansion, the fluid must be transferred from one side of the cylindrical housing to the opposite side of the cylindrical housing in the longitudinal direction since the chamber dividing bodies are contra-rotating and the screw only rotates in one direction. This may be implemented in a duct or pipe connection between one end of the housing and the opposite end of the housing.

In an embodiment of the invention, therefore, the screw shaft's helical grooves are provided at one or both ends in the longitudinal direction with a sealing termination, which sealing termination is provided with a through-flow opening which is coincident with the inlet and/or outlet opening in the cylindrical housing.

Furthermore, the screw shaft's helical grooves may be provided at one or both ends in the longitudinal direction with sealing terminations, which sealing terminations are each provided with one or more through- flow openings, whereof one of the through-flow openings is coincident with an inlet and/or outlet opening in the cylindrical housing and one of the through-flow openings at one end of the

cylindrical housing is connected to a through-flow opening at the other end of the cylindrical housing outside the internal cylindrical space.

In order to further facilitate the fluid flow and enable several grooves in the screw shaft to be employed simultaneously, in an embodiment there are provided at one or each end of the cylindrical housing in the longitudinal direction one or more chambers, each of which is connected to the cylindrical housing via a through-flow opening.

A rotary machine as indicated above may be employed, for example, as a compressor in one or more stages. In the case of such an application, non-return valves may be used in connection with the flow openings and/or in connection with transfer between different sides of the machine in the longitudinal direction in order to ensure that the fluid, which in the case of a compressor will preferably be gas, is compressed to for example a collecting chamber between two stages or during discharge or the like. Depending on the rotary machine's function and area of application, it may be necessary to provide cooling on the outside of the cylindrical housing, for example by means of cooling ribs or passages for liquid cooling. Adequate mounting and sealing naturally must also be provided for the various rotary shafts, for the chamber dividing bodies and for the screw shaft. Thus in different embodiments seals or one or more sealing devices may be mounted or provided at the screw shaft's outer edge against the cylindrical housing. In addition, a sealing device may be provided at the screw shaft's penetration into the housing. There may also be a sealing device at the chamber dividing body's edge against the inside of the helical groove. In order to ensure that the rotary machine can be connected to a gear connection, a generator, an engine or the like, the screw shaft may be provided with a shaft journal or a recess at least at one end for fixed or releasable connection to an engine or a drive gear.

In a preferred embodiment, the rotary machine according to the present invention may be employed as a combustion engine.

When the screw shaft rotates in the cylindrical housing, each helical groove will meet a chamber dividing blade on each of the chamber dividing bodies in the course of a rotational cycle. Each helical groove will thereby form two chambers - twice in the course of a cycle. One chamber will have increasing volume and the other chamber will have reducing volume. In other words, one chamber will suck while the next compresses. Moreover, one chamber will be able to be employed for expansion (increasing volume) and the next for displacement (reducing volume). By

using a connection between one end of the cylindrical housing and the opposite end in the longitudinal direction, as indicated above, it will therefore be possible to perform four passes in a continuous cycle in the engine. Amongst other things, this corresponds to the four strokes in a four- stroke combustion engine: induction, compression, expansion and exhaust. For example, when three helical grooves are employed, each undergoing division into two chambers each, this corresponds to six cylinders in a combustion engine. Each groove is divided into two chambers - twice in the course of a rotational cycle if there are two chamber dividing bodies, thereby performing the four strokes in the course of one rotational cycle - and in the course of two rotational cycles the engine will therefore perform the said four strokes six times when there are three helical grooves — which corresponds to a six-cylinder combustion engine with four strokes. The cylinder volume in each cylinder will correspond to the total volume of a helical groove. Thus the machine offers substantial savings in the number of movable parts and rotating mass compared to a conventional combustion engine with linear piston stroke and transfer from linear motion to rotating motion.

Since a rotary machine according to the invention transports or compresses a fluid in several chambers formed simultaneously in the helical screw grooves, it will also be possible to move the fluid between two or more different housings with screw shafts since it is not necessary for the fluid to move in chambers within the same screw shaft. This may be particularly advantageous in an application where, e.g., a rotary machine as indicated above is employed for compression ancf another, closely located rotary machine is used for combustion and expansion, for example as a combustion engine. This may have special advantages, for example in connection with cooling, balancing and construction of the rotary machine with special materials where the compressing (and possibly transporting) rotary machine can be made of an inexpensive material without special heat properties. A closely located rotary machine may be made of other materials that can withstand greater heat and higher pressure and can thereby be used for combustion and expansion of burnt gas in several chambers on several sides of the screw shaft, depending on how many helical grooves and chamber dividing bodies are provided.

According to the present invention, therefore, a special application of a rotary machine is provided substantially comprising two or more screw shafts, each supplied with one or more helical screw grooves, which screw shafts are designed at least at one end in the screw shaft's longitudinal direction for connection with an engine or a drive gear. The rotary machine is characterised in that: - the screw shafts are each rotatingly mounted in a housing with an internally cylindrical shape where the housing's internal diameter substantially corresponds to the external diameter of the screw shaft, each of which housings is substantially fluid-tight at the ends of the screw shaft with a through-going opening for the screw

shaft's connection with an engine or drive gear and each of which housings includes bearings for the screw shaft mounted internally in the housing,

- the helically-shaped screw grooves extend in a helical form from one end of the screw shaft to the opposite end of the screw shaft, - the rotary machine includes one or more rotatingly mounted chamber dividing bodies, each of which chamber dividing bodies is designed as a substantially circular body with a rotation centre, each of which chamber dividing bodies has a number of triangular chamber dividing blades protruding from the centre of the chamber dividing body with the narrowest end at the centre of the chamber dividing body, which chamber dividing blades are mounted at intervals and which chamber dividing bodies are rotatingly mounted at the outer edge of the screw shafts with a rotational axis substantially extending perpendicularly to the screw shaft's rotational axis and where the rotation of each of the chamber dividing bodies is synchronised with the rotation of the screw shaft, where the chamber dividing bodies are mounted so that the chamber dividing blades on the chamber dividing bodies project into the helical screw grooves in the screw shaft and follow the screw groove's movement when the screw shaft rotates so that a chamber dividing blade on a chamber dividing body follows a helical groove and divides the helical groove into a chamber on each side of the chamber dividing body on rotation of the screw shaft, which chambers have varying volume when the screw shaft rotates since the total volume of the helical groove is divided in two by the chamber dividing body and as the screw shaft rotates, the volume on each side of the chamber dividing body will be altered between substantially 0 and 100% and the two chambers together form at any time a total volume substantially equal to the volume of the helical screw groove,

- that at least one inlet opening is provided in each of the housings to the interior of the cylindrical housing into the respective helical screw groove at one end of the cylindrical housing and at least one outlet opening in each of the housings to the interior of the cylindrical housing into the respective helical screw groove at one of the ends of the cylindrical housing, and

- a fluid connection is created between at least one inlet opening in one of the housings and an outlet opening in another of the housings, with the result that fluid transported through the rotary machine moves between the different housings.

It is preferred that in such an application the screw shafts are synchronised with each other and have the same rotational speed. Different rotational speeds may, however, occur where, for example, the compressing or transporting screw shaft rotates faster and compresses fluid to an intermediate chamber before transfer to the next housing. In such an application non-return valves or pressure-controlled valves will be preferred in order to be able to build up pressure in the chambers for further use in the next housing.

If chamber dividing bodies are provided on opposite sides of the screw shafts' longitudinal direction, these chamber dividing bodies must be contra-rotating.

In different embodiments, the number of helical grooves in the screw shafts may be equal to the number of chamber dividing blades on the chamber dividing bodies, but it may also be different.

In order to achieve a good seal between the chamber dividing bodies and the helical screw groove in each of the screw shafts so that each helical screw groove is divided into different chambers by the chamber dividing body, the profile of each chamber dividing blade is preferably complementary in shape to the internal shape of the helical screw groove. The chamber dividing body may be flat on top and slightly conical with curved surfaces on the bottom, with the result that its shape is complementary to the screw groove and a seal is obtained with the screw groove when a chamber dividing blade moves into the screw groove and follows it while both the screw shaft and the chamber dividing body are rotating. The chamber dividing bodies may have a great many different shapes and in an embodiment may be a flat disc or plate. The chamber dividing bodies may also have a flat top and a curved or pyramidal bottom or they may be more spherical in shape. As long as the chamber dividing body or at least each chamber dividing blade has a shape that is complementary to the interior of the helical groove, the chamber dividing bodies and/or the chamber dividing blades may otherwise be designed in a suitable manner with regard to heat development, pressure ratio, bearings, etc.

The cylindrical housings in which the screw shafts move has an interior cylindrical shape and the exterior may be of any shape whatever, thereby enabling it to form part of a larger structure. Several rotary machines according to the invention may, of course, by mounted side by side or on top of one another or in some other way. In some embodiments several housings may also be provided, so that two housings also divide a chamber dividing body, i.e. the chamber dividing body protrudes simultaneously into two helical grooves with different chamber dividing blades. In such embodiments the rotation of each screw shaft must be synchronised with one another and with the chamber dividing body.

The screw shafts are suitable for transporting and possibly compressing a fluid such as a liquid or gas. To enable the fluid to be admitted to the helical groove in the rotary machine, an inlet opening is therefore provided through the housing in towards the screw shaft. The inlet opening is preferably located on the side of the screw where the chamber dividing body moves into the helical screw groove, with the result that when the screw and the chamber dividing body rotate, a chamber is created where the volume expands, thereby causing the fluid to be drawn into the chamber. Once the screw shaft has moved so that the chamber dividing blade has followed the helical groove to the end, the valve surface leaves the helical groove

and the chamber is filled with fluid. The next valve surface will then enter the helical groove on continued rotation of the screw shaft and push the fluid content in the helical groove forwards in the groove as the chamber dividing blade moves along the helical groove, forming a chamber that has reducing volume. If the end of the chamber is closed, the chamber dividing blade will compress the fluid against the closed surface. If not, the movement of the chamber dividing body will be able to push the fluid out of the chamber created upstream (the pushing side) of the chamber dividing body. As the screw shaft rotates the chamber with reducing volume will be able to meet an outlet opening from the cylindrical housing and from the helical screw groove, as indicated above and pressurized fluid will flow out. The conclusion of this "emptying" of the chamber occurs when the chamber dividing blade leaves the helical groove and the screw shaft continues to rotate with an empty groove. Whether a compression is to be created or only a "movement" of fluid through the helical groove is therefore determined amongst other things by the location of an outlet opening and the shape of the outlet opening. If the opening is an elongated slot which is open to the chamber with reducing volume, the fluid in the chamber will be pushed out all the time. If the opening is small in area and located in such a manner in the cylindrical housing that the opening is only uncovered when the chamber dividing body has passed almost through the entire helical groove, a pressure will be created in the chamber by the helical groove that has reducing volume and it will be pressurized fluid that flows out of the outlet opening. Alternatively, the fluid may be continuously pushed into a chamber through a pressure-controlled or non-return valve, thereby creating pressure in the chamber when the pressure in the chamber in the helical groove exceeds the predefined pressure in the valve.

In an embodiment, therefore, a through-flow opening may have a length in the rotational direction corresponding to the whole or parts of the rotational angle over which the helical groove in the screw shaft extends.

If the pressurized fluid has to perform several passes through the screw shaft or between several screw shafts, for example for combustion of pressurized fluid and expansion, the fluid must be transferred from one side of the cylindrical housing to the opposite side of the cylindrical housing in the longitudinal direction since the chamber dividing bodies are contra-rotating and the screw only rotates in one direction or to the opposite side (if the screws rotate in the same direction) in the next housing. This may be implemented in a duct or pipe connection between one end of the housing and the opposite end of the housing or the next housing. Thus in a preferred embodiment several housings with screw shafts may be provided behind one another in the longitudinal direction so that discharge from the first is transferred immediately to the inlet in the next housing.

In an embodiment of the invention, therefore, the screw shaft's helical grooves are provided at one or both of their ends in the longitudinal direction with a sealing termination, which sealing termination is provided with a through-flow opening which is coincident with the inlet and/or outlet opening in the cylindrical housing. Furthermore, the screw shaft's helical grooves may be provided at one or both of their ends in the longitudinal direction with sealing terminations, which sealing terminations are each provided with one or more through-flow openings, whereof one of the through- flow openings is coincident with an inlet and/or outlet opening in the cylindrical housing and one of the through- flow openings at one end of the cylindrical housing is connected to a through-flow opening at the other end of the cylindrical housing outside the internal cylindrical space or another housing.

In order to further facilitate the fluid flow and enable several grooves in the screw shaft to be employed simultaneously, in an embodiment there are provided at one or each end of the cylindrical housing in the longitudinal direction one or more chambers, each of which is connected to the cylindrical housing via a through- flow opening. In this application where several housings with screw shafts are employed, several housings may divide one and the same or several chambers.

A rotary machine as indicated above may be employed, for example, as a compressor in one or more stages. In the case of such an application, non-return valves may be used in connection with the flow openings and/or in connection with transfer between different sides of the machine in the longitudinal direction in order to ensure that the fluid, which in the case of a compressor will preferably be gas, is compressed to for example a collecting chamber between two stages or during discharge or the like. Depending on the rotary machine's function and area of application, it may be necessary to provide cooling on the outside of the cylindrical housing, for example by means of cooling ribs or passages for liquid cooling. Adequate mounting and sealing naturally must also be provided for the various rotary shafts for the chamber dividing bodies and for the screw shaft. Thus in different embodiments seals or one or more sealing devices may be mounted or provided at the screw shaft's outer edge against the cylindrical housing. In addition, a sealing device may be provided at the screw shaft's penetration into the housing. There may also be a sealing device at the chamber dividing body's edge against the inside of the helical groove. In order to ensure that the rotary machine can be connected to a gear connection, a generator, a motor or the like, the screw shaft may be provided with a shaft journal or a recess at least at one end for fixed or releasable connection to a motor or a drive gear.

In a preferred embodiment, the rotary machine according to the present invention may be employed as a combustion engine.

When the screw shafts rotate in each of the cylindrical housings, each helical groove will meet a chamber dividing blade on each of the chamber dividing bodies in the course of a rotational cycle. Each helical groove will thereby form two chambers — twice in the course of a cycle. One chamber will have increasing volume and the other chamber will have reducing volume. In other words, one chamber will suck while the next compresses. Moreover, one chamber will be able to be employed for expansion (increasing volume) and the next for displacement (reducing volume). By using a connection between one end of the cylindrical housing and the opposite end in the longitudinal direction or transfer to another housing, as indicated above, it will therefore be possible to perform four passes in a continuous cycle in the machine or in two succeeding housings forming a machine. Amongst other things, this corresponds with the four strokes in a four-stroke combustion engine: induction, compression, expansion and exhaust. For example, when three helical grooves are employed, each undergoing division into two chambers each, this corresponds to six cylinders in a combustion engine. Each groove is divided into two chambers — twice in the course of a rotational cycle if there are two chamber dividing bodies, thereby performing the four strokes in the course of one rotational cycle - and in the course of two rotational cycles the engine will therefore perform the said four strokes six times when there are three helical grooves - which corresponds to a six-cylinder combustion engine with four strokes. The cylinder volume in each cylinder will correspond to the total volume of a helical groove. Thus the machine offers substantial savings in the number of movable parts and rotating mass compared to a conventional combustion engine with linear piston stroke and transfer from linear motion to rotating motion.

According to the present invention a combustion engine is further provided based on the rotary machine as indicated above in one of the two applications. The combustion engine substantially comprises at least one screw shaft with one or more helical screw grooves, which screw shaft is designed at least at one end in the screw shaft's longitudinal direction for connection with an engine or a drive gear. The combustion engine is characterised in that:

- the screw shaft is rotatingly mounted in a housing with an internally cylindrical shape where the housing's internal diameter substantially corresponds to the external diameter of the screw shaft, which housing is substantially sealed at each end of the screw shaft with a through-going opening for the screw shaft's connection with an engine or drive gear and which housing includes bearings for the screw shaft,

- the helically-shaped screw grooves extend in a helical form from one end of the screw shaft to the opposite end of the screw shaft,

- the combustion engine includes one or more rotatingly mounted chamber dividing bodies, each of which chamber dividing bodies is designed as a substantially circular body with a rotation centre, each of which chamber dividing bodies has a number of triangular chamber dividing blades protruding from the centre of the chamber dividing body with the narrowest end at the centre of the chamber dividing body, which chamber dividing blades are mounted at intervals and which chamber dividing bodies are rotatingly mounted at the outer edge of the screw shaft with a rotational axis substantially extending perpendicularly to the screw shaft's rotational axis and where the rotation of each of the chamber dividing bodies is synchronised with the rotation of the screw shaft, with the result that the chamber dividing blades on the chamber dividing bodies project into the helical screw grooves in the screw shaft and follow the screw groove's movement when the screw shaft rotates so that a chamber dividing blade on a chamber dividing body follows a helical groove and divides the helical groove into a chamber on each side of the chamber dividing body on rotation of the screw shaft, which chambers have varying volume when the screw shaft rotates since the total volume of the helical groove is divided in two by the chamber dividing body and as the screw shaft rotates, the volume on each side of the chamber dividing body will be altered between substantially 0 and 100% and the two chambers together form at any time a total volume substantially equal to the volume of the helical screw groove, and

- that at each end of the cylindrical housing in the longitudinal direction or in connection with several cylindrical housings there are formed four chambers A-D where the first chamber A and the third chamber C are mounted on the same side of the cylindrical housing and the second chamber B and the fourth chamber D are mounted on the same side of the cylindrical housing,

- where the first chamber A has a through- flow opening to the exterior of the engine and a through-flow opening into the cylindrical housing,

- the second chamber B has a through-flow opening into the cylindrical housing and a through- flow opening into a flow transfer body, which flow transfer body leads from the through-flow opening in the second chamber B to a through-flow opening into the third chamber C,

- the third chamber C has a through-flow opening to the flow transfer body together with a through-flow opening to the cylindrical housing,

- the fourth chamber D has a through-flow opening to the cylindrical housing and a through- flow opening to the exterior of the engine, and

- that a fuel supply device is provided upstream in the rotation process for the third chamber C or at the third chamber C.

There may be a great variation in the size of each of the chambers A-D and these chambers may be extremely small, i.e. they are comprised of the volume in the transfer body for example to the next chamber. This will be dependent on design

and requirement for pressurization, fluid transfer and volume storage for further treatment in the next chamber in the screw shaft.

Fuel can be supplied in connection with the transfer of pressurized gas from the second chamber B to the third chamber C or alternatively fuel may be added before the gas is drawn into the first chamber A or any place therebetween. Fuel will preferably be added by otherwise known means and the fuel may be a combustible liquid based on oil such as petrol or diesel or it may be an alcohol or synthetically produced fuel. In addition, different mixtures of these may be employed or a combustible gas such as, for example, hydrogen. In different embodiments the combustion engine may substantially also comprise an ignition device in connection with the cylindrical housing at the third chamber C. It will be natural to use an ignition device adapted to the fuel supplied and if the fuel is expected to be capable of spontaneous ignition under special conditions that may be encountered in the combustion engine, an ignition device may, for example, be omitted or used only in connection with a cold combustion engine, and subsequently uncoupled when operating temperature or other appropriate operating conditions are achieved. In an embodiment the ignition device may provide spark ignition and is synchronised with the screw shaft. This will usually be a spark plug and a unit with charging of one or more coils may, for example, be employed while the charging thereof is carried out synchronised with the rotation of the screw shaft, with the result that the spark ignites the fuel-supplied, compressed gas mixture at the correct time.

Alternatively, the ignition device may be a hot bulb device.

In different embodiments the chambers on each side of the cylindrical housing may have a number of different positions and shapes. In one embodiment the chambers A-D may be substantially semicircular and may be mounted in such a manner that together they form a cylindrical chamber on each side of the cylindrical housing.

In order to ensure that the gas exchange between the cylindrical housing and the various chambers as mentioned above are optimal for achieving a good through- flow of gas in the combustion engine according to the invention, the through- flow openings between the chambers and the cylindrical housing must be well-matched to the through-flow openings in the sealed ends of the screw shaft while at the same time they must be adapted for gas exchange through the rotational cycle of the screw shaft. This is implemented by designing the through-flow openings particularly between the chamber and the cylindrical housing with a suitable length relative to the proportion of the rotational angle completed by the screw shaft where a chamber dividing blade moves through a helical groove. In other words, it there is to be an opening in towards the helical groove for a long period, for example during expansion of the space in the helical chamber, the opening must cover a substantial

part of the rotational angle through which the helical groove moves when rotating. If the helical groove moves through 180 degrees of the screw shaft, the through- flow opening should be an elongated slot covering approximately this area or a corresponding area, i.e. a semicircular slot. In the preferred embodiment different through-flow openings are indicated. The through-flow opening between the first chamber A and the cylindrical housing may be in the form of a slot, extending for a distance substantially equivalent to a large part of the rotational angle over which the helical groove in the screw shaft extends. This ensures a good influx of gas (e.g. air) from the outside of the engine through the chamber A as the opening in towards the cylindrical housing permits gas to flow into the cylindrical housing continuously while the screw shaft is rotating through a rotational angle corresponding substantially to the rotational angle of the helical groove. Furthermore, the through- flow opening between the second chamber B and the cylindrical housing may extend for a distance corresponding substantially to the whole or parts of the rotational angle over which the helical groove in the screw shaft extends. The through-flow opening between the third chamber C and the cylindrical housing may extend for a distance corresponding substantially to a smaller part of the rotational angle over which the helical groove in the screw shaft extends and the through- flow opening is provided substantially upstream in the chamber relative to the screw shaft's rotational direction. This causes the opening between the third chamber C and the cylindrical housing to be uncovered immediately when the chamber in the helical groove is extremely small and where the chamber will expand due to the rotation of the screw shaft and the chamber dividing blade's movement in the groove. Pressurized gas will thereby be able to flow rapidly into a relatively small chamber and this will continue while the chamber in the helical groove expands

(thereby sucking gas out of the chamber C) until the through-flow opening into the cylindrical housing from the third chamber C is covered by the sealing end surface of the screw shaft. Ignition of the gas confined in this chamber in the screw shaft's helical groove may then lead to an additional expansion which drives the screw shaft round. It will be obvious that this will result in a relatively high pressure against the chamber dividing blade in this helical groove and the chamber dividing blade as well as the chamber dividing body's bearings, design and dimensions must therefore be adapted in order to be able to withstand this pressure. Furthermore, the exhaust created in this chamber will follow the helical groove further on where the next chamber dividing body will push a chamber dividing blade into this groove and will be able to create a chamber with reducing volume, with the result that the exhaust is forced out towards the fourth chamber D. In order to facilitate a continuous easy flow of exhaust out of the chamber in the helical groove, the through- flow opening between the fourth chamber D and the cylindrical housing should be open through substantial parts of or substantially the whole of the rotational angle covered by the screw shaft in order to push the chamber dividing blade through the entire helical screw groove which is filled with exhaust. This can

be implemented by the through-flow opening between the fourth chamber D and the cylindrical housing being in the form of a slot extending a distance equivalent substantially to a large part of the rotational angle over which the helical groove in the screw shaft extends. As in the case of the above-described rotary machine, chamber dividing bodies mounted on opposite sides of the screw shaft's longitudinal direction must be contra-rotating. Moreover, it is preferred that the number of helical grooves in the screw shaft correspond to the number of chamber dividing blades on the chamber dividing bodies and that the profile of each chamber dividing blade is complementary to the internal shape of the helical screw groove. The chamber dividing bodies may be synchronised with the rotation of the screw shaft via a gear transmission or the chamber dividing bodies may be synchronised with the rotation of the screw shaft via an electrical transmission and electronic control of a motor that drives each of or several of the chamber dividing bodies. Thus in different embodiments seals or one or more sealing devices may be provided or mounted at the screw shaft's outer edge against the cylindrical housing. Furthermore, a sealing device may be provided at the screw shaft's penetration into the housing. There may also be a sealing device at the edge of the chamber dividing body against the inside of the helical groove. Substantially two embodiments of the invention will now be illustrated with reference to the attached figures.

Figure 1 is a sectional view from above of an embodiment of a rotary machine with screw shaft together with the chamber dividing bodies according to the invention in a first position. Figure 2 is a perspective view of the rotary machine in figure 1.

Figure 3 is a sectional view from above of an embodiment of a rotary machine with screw shaft together with the chamber dividing bodies according to the invention in a second position.

Figure 4 is a perspective view of the rotary machine in figure 3. Figure 5 is a sectional view from above of an embodiment of a rotary machine with screw shaft together with the chamber dividing bodies according to the invention in a third position.

Figure 6 is a perspective view of the rotary machine in figure 5.

Figure 7 is a principle view of a combustion engine based on the rotary machine illustrated in figures 1-6.

Figure 1 is a general view of the essential parts of a rotary machine according to the invention as described above.

Figures 1 and 2 illustrate a screw shaft 1 with helical grooves 2, 3 and 4. On each side of the screw shaft are illustrated chamber dividing bodies 10 and 20 with rotation centres 11 and 21 respectively and chamber dividing blades 12, 13 and 14 plus 22, 23, 24. In the figure the chamber dividing blade 22 is on its way into the helical groove 3 and the chamber dividing blade 13 has halfway completed its movement through the helical groove 2 while the chamber dividing blade 23 is on its way out of the helical groove 4. When the chamber dividing blade 22 moves through the helical groove 3, an expanding volume is created downstream (on the back) of the blade 22 and fluid is drawn into this expanding chamber until it is filled (when the chamber dividing blade leaves the screw groove). At the same time the content is pushed upstream (on the front) of the chamber dividing blade 22 through the screw and out at the other end of the screw shaft. This is the content of the helical groove 3.

In figs. 3 and 4 the chamber dividing blade is halfway into the helical groove 3. The chamber dividing blade 13 is halfway through the helical groove 2.

In figures 5 and 6 the chamber dividing blade 22 is on its way out of the helical groove 3 while the chamber dividing blade 24 is on its way into the groove 2. The chamber dividing blade 13 has left the groove 2 and chamber dividing body 14 is on its way into the groove 1.

In figure 7 a combustion engine according to the present invention is illustrated with a screw shaft and a housing together with chamber dividing bodies.

The screw shaft has three helically shaped grooves (1, 2, 3) which abut sealingly against the inside of the cylindrical housing. Between these three wings there are thereby formed three helically shaped raised portions which provide a seal against the inside of the cylindrical housing. In its longitudinal direction the screw shaft has a first and a second end. In the preferred embodiment a shaft journal protrudes from the housing at the second end. The engine is depicted with two semicircular chambers at each end. At its first end the engine has a chamber B for compressed gas which is compressed to the chamber B of the screw shaft in the upper half and an exhaust chamber D in the lower half with an outlet for exhaust or possibly to an exhaust system.

At its second end the housing has a chamber A for induction of air, possibly connected to an induction manifold. At the second end there is also a chamber C for pressurized gas which is transported from the chamber B through a fluid connection on the outside of the cylindrical housing. In connection with the chamber C, fuel is

added to the gas even though this may be performed at any point after the gas flows into the chamber A or also before this.

The screw shaft is sealed at its ends (a leak-proof plate) against the first and second ends of the housing except for an opening in each of the helical grooves at the first end and the second end of the helical recess. In other words, these openings are displaced 180 degrees along the rotational axis of the rotor. These openings create a connection between the chambers A, B, C and D through the cycle.

The chambers A and D (induction of air and discharge of exhaust) have slot-shaped openings against the screw shaft's helical groove, with the result that air is drawn in continuously on expansion of the volume in the helical groove and exhaust is forced out on reduction in the volume in the helical groove after combustion by means of the chamber dividing blade on the chamber dividing body on rotation of the rotor.

The rotating chamber dividing bodies on each side of the screw have a number of chamber dividing blades corresponding to the number of helically shaped grooves in the rotor. These chamber dividing blades on each side of the rotating screw shaft divide each helical groove into two chambers which thereby obtain varying volume. If the helical recesses are twisted over more than 180 degrees of the rotor's circle, in some cases the chamber dividing blades on the rotating chamber dividing bodies will divide a helical groove in the screw shaft into three individual chambers. This is of little importance, however, since this only occurs for a brief moment and it is only two of these chambers (the two foremost in the rotational direction) that contribute to the combustion engine's driving cycle. The helical grooves are therefore divided at all times into six chambers which participate in the cycle. This corresponds to six cylinders in a piston engine. The engine, moreover, goes through the four strokes in a conventional four-stroke engine: induction, compression, expansion as a result of combustion, discharge of exhaust. Induction occurs on expansion of volume and discharge occurs on displacement of exhaust (reduction of volume).

The rotating chamber dividing bodies with chamber dividing blades (equal number to the helical grooves) are driven by a transmission from the rotor (for example a gear wheel) in a 1 :1 ratio, i.e. these chamber dividing bodies rotate at the same rate as the screw shaft, in contrast to a conventional combustion engine with transfer from linear motion to rotating motion (piston engine) where the transmission ratio between drive shaft and camshaft for control of valves is 2:1. The chamber dividing bodies are contra-rotating (opposite ways) towards the engine's second end.

The combustion engine operates in a cycle where air is drawn into a first chamber A (on the second end of the engine casing) by the chamber being connected to a helical groove in the screw shaft which on rotation of the screw shaft has an increasing volume, thereby sucking the air into this space. The helical groove is

bounded at each end by a chamber dividing blade on each of the rotating chamber dividing bodies and when the rotation continues, an opening to the chamber B is uncovered on the opposite side of the casing, i.e. at the first end of the casing. The air in the groove is then forced into the chamber B by the volume of the helical groove being reduced through rotation towards the chamber dividing blade on the rotating chamber dividing body that bounds this helical groove. In other words, the gas is compressed into the chamber B. This takes place since the chamber B is connected to the chamber A and acts as a balancing chamber in order to create a more constant pressure in towards the combustion chamber in the screw shaft. During this phase fuel may also be added to the compressed air. Alternatively, fuel may be completely or partly added to the air drawn into the induction to chamber A.

The pressurized gas (possibly with fuel) is transferred via a flow transfer such as, e.g. a duct or a pipe to the chamber C which also acts as a balancing chamber and supply chamber to the combustion "chamber" in the screw shaft. A non-return valve may be provided between the chambers B and C. This valve may also be designed so as to be pressure-controlled and only opens when the pressure in the chamber B is over a predetermined limit.

The through-flow opening in the end seal for the screw shaft towards the induction chamber A is downstream in the rotational cycle. The through-flow opening in towards the chamber B is downstream in the rotational direction with the result that only compressed air is admitted to B.

The through-flow opening from the chamber C towards the screw shaft is upstream (early) in the rotational cycle with the result that pressurized air/fuel is admitted to the rotor's helical recess when it is small. This opening is only open when the opening in the rotor's end seal corresponds to the opening in towards the chamber, i.e. only for a brief moment. This connection is then closed and the spark plug (in the casing in towards the screw shaft) ignites. This drives the rotor round on expansion of the space by combustion gas. This takes place over 180 degrees (corresponding to a full stroke in a piston engine), whereupon the opening in the end seal of the screw shaft is released towards the chamber D which has a slot opening in towards the cylindrical casing in order to be able to receive exhaust gas that is pushed out through almost 180 degree rotation of the screw shaft before the opening in the screw shaft's end seal disappears behind the end seal in the chamber B in towards the screw shaft. On the opposite side of the chamber dividing blade on the chamber dividing body α, the helical recess which has just delivered exhaust (which continuously pushes out exhaust) will begin to suck in gas that has to be compressed.

A helical groove is thereby divided into two chambers by the chamber dividing body α. These are a chamber for pushing out exhaust and a chamber for sucking in gas. The upstream chamber sucks in, while the downstream chamber pushes out.

The same helical groove is divided into two chambers by the chamber dividing body β where one chamber is in compression and one chamber is in combustion (expansion of gas). The upstream chamber (in the rotational direction) compresses while the downstream chamber (after the chamber dividing body β) is in combustion and expansion of gas.