NO320961B1 - An energy - Google Patents

Abstract

An energy converter, particularly for use as a hydrodynamic pump, compressor, motor or turbine, comprising a stator (1) with a bore (4), where at least one helical groove (8) is formed in the wall of the bore (4), and a rotor (2) with an external surface (10), where at least one helical groove (18) is formed in the outer surface (10). The stator (1) and the rotor (2) are designed to rotate relative to each other, and at least the rotor (1) is designed to be coupled to a shaft (3) for transmission of torque. The bore (4) in the stator (1) and the external surface (10) of the rotor (2) are conical with a complementary taper.

Description

The present invention relates to an energy converter in accordance with the preamble of the subsequent claim 1.

A number of pumps are known for pumping fluids and motors which are wholly or partly based on the utilization of the energy in fluids. Often, one and the same unit will be able to function both as a pump, compressor, motor and turbine with simple adaptations. This is also the case with the energy converter according to the present invention.

As an example of the state of the art, GB 2234SS7 describes a hydroelectric generator in which two rotatable cylinders are arranged one inside the other. Each of the cylinders has helical flow paths, which are oppositely directed. The cylinders will thereby rotate in the opposite direction in relation to each other. The rotation is transmitted via a system of gears to an electric generator. The cylinders have the same cross-section over their entire length.

GB 1573334 describes a cylindrical water wheel with blades which are twisted helically about the axis. It is placed inside a chamber with smooth walls. The water wheel and the chamber have the same cross-section over the entire active length.

US 4378195 describes a cylindrical rotor with a rough surface which is placed inside a chamber with smooth walls. Here, too, the chamber and the rotor have the same cross-section over the entire length.

US 4412417 describes a wave power plant in which a rotor is equipped with at least two helical blades, which are slightly offset in relation to each other. The rotor not placed in any housing. The rotor has the same cross-section over its entire length.

US 5313103 describes a type of windmill with a rotor having a helical blade. This is also not placed in any house. The rotor has the same cross-section over its entire length.

DE 3802069 also describes a kind of windmill. Here the rotor is conical with a set of helical blades. However, there is no rotor chamber.

GB 1157273 describes a screw motor, where two oppositely twisted helical blades are placed one behind the other on the same shaft inside a chamber with smooth walls. Both the rotor and the chamber have the same cross-section over the entire length.

WO 94/13957 describes an impeller. Here the rotor is composed of helical blades attached to a conical central body. The rotor chamber has smooth walls.

GB 98714 describes a mixer, which is specially designed for mixing plastic material. The mixer comprises a rotor and a stator, both of which are equipped with helical grooves. The helical grooves of the rotor and stator can be turned in opposite directions. Here, the tracks have an approximately rectangular cross-section.

The present invention aims to provide an energy converter, in particular for use as a hydraulic pump, compressor, motor or turbine, for cooperation with one or more fluids, which is flexible in use, has low internal friction, is easy to manufacture with low requirements to tolerances and which has great applicability in several areas of use. This is achieved by the features that appear in the characterizing part of the following claim 1.

The bore of the first part and the outer surface of the second part are tapered with complementary taper. In what follows, the terms conical and cone mean all shapes that have a smaller diameter at one end than at the other end. This does not necessarily mean that the diameter should increase uniformly. A machine according to the invention, which for example has parts with a "bottle shape" will also be able to be used.

The invention will now be explained in more detail with reference to the accompanying figures, where: Figure 1a in a schematic diagram shows a unit for an energy converter according to the present invention,

Figure 1b shows the unit according to Figure 1 a seen in the direction of arrow A,

Figure lc shows the unit according to figure la seen in the direction of arrow B,

Figure 2 illustrates the working principle of the present invention,

Figure 3 shows the stator according to Figure la,

Figure 4 shows the rotor according to Figure la and

Figure 5 schematically illustrates a practical application of the energy converter according to the invention.

Figure la shows an embodiment of a unit for an energy converter according to the present invention. In figure la, one can imagine that both rotor and stator are shown to be partially transparent. The unit consists of a stator 1 and a rotor 2. A shaft 3 is attached to the rotor.

Figure 3 schematically illustrates the stator 1. One can also imagine here that the rotor and the stator are shown to be partially transparent. It has an internal bore 4 which is conically designed with its smallest diameter D1 on the left in Figure 3 and its largest diameter D2 on the right in the figure. Conveniently, a smaller part 5 at the smallest diameter Dl is designed with a uniform diameter, while the rest of the stator has an inner surface 6 which forms an angle a with the stator's outer cylindrical surface 7. The angle a is suitably between 1° and 3°.

In the inner surface 6, helical grooves 8 are formed. Appropriately, several helical grooves are formed which are offset somewhat in relation to each other. In the design example shown, 12 helical grooves are designed which are turned at a 45° angle to the longitudinal axis of the stator. The number of tracks can be more or less than this and the angle can also be greater or less than 45°.

The portion 5 with a uniform diameter suitably comprises between 5% and 20% of the stator's length. The diameters D1 and D2 conveniently amount to approx. 1/3 to 1/5 of the total length of the stator.

The grooves 8 are very shallow at the stator 1's largest diameter D2 (on the right in Figure 3) and have a depth approximately equal to zero at this end of the stator 1. The depth of the grooves gradually increases towards the opposite end of the stator at diameter Dl (on the left in Figure 3) . Here, the grooves 8 reach a depth approximately equal to the diameter D2, so that the bottom of the grooves 8 lies on an imaginary cylindrical surface corresponding to the diameter D2. This simplifies the production of the stator 1 considerably, as will be explained below. However, this is not critical for the function and for stators that are cast to the finished form, the bottom of the slots will also be able to lie on an imaginary cone. The pitch for the tracks 8 can be the same over the entire length of the stator or vary.

Figure 4 shows the rotor 2. The rotor 2 has a cone-shaped outer surface 10, which forms an angle a with an imaginary cylinder circumscribing the rotor 2. The angle a is the same as for the stator 1. The rotor 2 has its largest diameter D3 at the end where the shaft 3 is attached. Here there is also a lot 15 with a uniform diameter. The diameter D3 can be approximately equal to the stator's largest diameter D2. The rotor's smallest diameter D4 is Uk or less than the stator's 1 smallest diameter Dl.

In the surface 10 of the rotor, grooves 18 have been formed corresponding to the stator's grooves 8. The grooves should be of the same number and with the same pitch angle as the grooves 8 for the stator 1, but may also differ both in number and pitch. However, the grooves 18 are turned in the opposite direction to the grooves 8 in the stator 1. To achieve the best possible degree of excitation, the grooves in the stator 1 and the rotor 2 must cross each other at 90°.

The portion 15 with a uniform diameter suitably constitutes between 5% and 20% of the length of the rotor. The diameters D3 and D4 conveniently amount to approx. 1/3 to 1/5 of the rudder's total length.

The grooves 18 are very shallow at the smallest diameter D4 of the rotor 2 (on the left in figure 4) and have a depth approximately equal to zero at this end of the rudder 2. The depth of the grooves gradually increases towards the opposite end of the rudder at diameter D3 (on the right in figure 4) . Here, the grooves 18 reach a depth approximately equal to the diameter D4, so that the bottom of the grooves 18 rests on an imaginary cylindrical surface corresponding to the diameter D4. This simplifies the manufacture of the rudder 2 considerably, as will be explained below. However, this is not critical for the function and for rotors that have been cast to a finished shape, the bottom of the grooves will also be able to lie on an imaginary cone. The pitch for the grooves 18 can be the same over the entire length of the rotor or vary.

The stator 1 and the rotor 2 are conveniently approximately the same length.

When the rotor 2 is inserted into the stator 1 as shown in Figure 1a, there will conveniently be a part of the rotor 2 that protrudes from the stator 1, and correspondingly a part of the stator 1 that is not overlapped by the rotor 2. The meaning of this shall explained in more detail below. However, the energy converter will also work perfectly if the rotor can be completely inserted into the stator. Figure lb shows the unit in figure la seen in the direction of arrow A in figure la. Here you can see the entrance to the 12 slots 8 in the stator at their greatest depth. The rotor 2 appears with a smooth surface here, because the grooves in the rotor have approximately zero depth at this end of the unit. Figure lc shows the unit in figure la seen in the direction of arrow B in figure la. Here you can see the entrance to the 12 slots 18 in the rotor at their greatest depth. The stator 2 appears with a smooth surface here, because the slots in the stator have approximately zero depth at this end of the unit.

The unit's function will now be explained in more detail with reference to Figure 2, where, to illustrate the principle, one track 18 has been taken out from the rotor and one track 8 from the stator. For this example, the unit is intended to be used as a hydraulic motor. Fluid flows in at the stator 1 end with at least diameter Dl (see arrow A in fig. 1), but with the greatest groove depth. Since the grooves in the rotor 2 at this end of the unit have zero depth, the fluid will flow along the grooves 8 in the stator 1. However, the grooves 8 in the stator 1 become shallower as the fluid flows along the groove 8. At the same time, the groove 18 in the rotor 2 becomes deeper. The fluid will therefore be forced to flow into the groove 18 in the rotor 2. Figure 2 shows a situational picture at a given time for two grooves, a groove 8 in the stator 1 and a groove 18 in the rotor 2. Here you can see that the groove 8 and the track 18 intersects each other approximately perpendicularly at the point X at this given time. Some of the fluid will therefore here flow over from groove 8, which has a constantly decreasing cross-section, to groove 18, which has a constantly increasing cross-section. At the same time, the fluid must change direction by 90° (here from flowing down to the right to flowing up to the right). This belt tensioning means that a force is applied to the rotor 2, and this is thereby forced to rotate.

Since the rotor rotates and there are a large number of slots in the rotor and in the stator, one will get a. large number of crossing points that are constantly moving. Fluid will therefore continuously flow over from the grooves 8 to the grooves 18 and help to increase the rotation of the rotor and thereby increase the energy transfer. The rotational torque can then be extracted on the shaft 3 and used for, for example, operation of a generator. The more slots you have in the rotor and stator, the more crossing points you will get and the smoother the unit will run and the better the efficiency will be.

For use as a pump, the unit will work in the opposite way, as rotation of the rotor 2 creates a negative pressure in the grooves 8 in the stator 1, which sucks fluid into the grooves 8, while at the same time an overpressure is created in the grooves 18, which pushes the fluid out at the opposite end of the pump.

Using the unit as a compressor is in principle the same as using it as a pump. It is also conceivable to use the unit as a fuel turbine, as combustion of a fuel is initiated at the entrance to the turbine, and the fuel and any expansion gas expand through the turbine. However, this will result in the unit, due to volume expansion, having to be designed with a relatively small inlet area and a relatively large outlet area.

The net opening area (throughflow area) through the unit will typically be in the range of 30 - 40% of the axial cross-sectional area of the stator, preferably 35 - 37%, which gives a large girder circulation in relation to its size. When the unit is used as a liquid turbine or pump, it is important that the flow area is approximately the same throughout the unit, to avoid cavitation due to local pressure drops or pressure increases.

It is also important that the angle a for the conicity of the bore in the stator and the outer surface of the rotor is approximately the same, to avoid leakage and backflows, which can reduce efficiency and cause heat transfer.

Figure 5 schematically shows a practical example of using the unit, here for pumping oil, where oil is also used as a driving medium.

A hydraulic motor 20 and a hydraulic pump 21 are placed in a common housing 22.

The motor 20 has a stator 20a, which is fixed in relation to the housing 22 in that it is attached to a dividing wall 24, and a rotor 20b. The pump 21 has a stator 21a, which is fixed in relation to the housing 22 in that it is attached to a dividing wall 25, and a rotor 21b. The rotors 20b and 21b are connected to a common shaft 23.

The pump 21 has a larger displacement volume than the motor 20. The pump 21 and the motor 20 are arranged so that the outlet end of the motor 20 faces the inlet end of the pump 21.

An inlet 26 for drive fluid is arranged at the inlet end of the motor 20 to the left of the partition wall 24. An inlet 27 for pump medium is arranged between the partition walls 24 and 25 and an outlet 28 for both drive medium and pump medium is arranged at the outlet end of the pump 21 to the right of the partition wall 25.

Drive medium, for example oil, is supplied under pressure through the inlet 26 and is forced through the motor 20. This sets the rotor 20b of the motor 20 in rotation and, through the shaft 23, in turn drives the rotor 21b of the pump 21. As the pump 21 has a larger displacement volume than the motor 20, a negative pressure will be created in the chamber between the dividing walls 24 and 25. This means that pump medium is sucked in through the inlet 27, mixes with the drive medium flowing out of the motor 20's outlet end and is drawn through the pump 21. The combined fluid flow is then forced out through the outlet 28. The purpose of this solution is that the energy in liquid with high pressure is converted into mechanical rotating energy which drives a larger low-pressure machine, which converts mechanical energy into liquid energy, however with a lower pressure, but with a significantly larger amount.

Instead of using the same fluid as the drive medium to be pumped, you can also place a dividing wall between the motor and the pump and arrange an outlet for the drive medium to the left of this dividing wall. Thereby, it is possible to use a different drive medium than the fluid to be pumped. However, it is the property of utilizing the same fluid that makes the converter particularly useful, because it avoids sealing problems and the mixing of different fluids.

Another very relevant application of the energy converter according to the invention is i

connection with hydropower. The energy converter according to the invention is particularly suitable for extracting energy at high pressure. It will therefore be particularly appropriate to use the energy converter as a turbine when utilizing smaller hydropower resources, i.e. hydropower resources with a relatively small amount of water, but a large drop height. The energy converter according to the invention is also suitable in connection with wave power plants. In this case, the pressure is relatively low, while the amount of water is large. However, this means that the energy converter's length/diameter ratio must be changed, by increasing the diameter, so that the passage area increases.

The energy converter can also be used as an expanding machine, for example as an internal combustion engine. Preferably, the flow area must then increase in the direction of flow of the combustion medium. This can be done, for example, by increasing the width of the tracks in the direction of flow.

The energy converter is particularly advantageous to produce, because it makes low demands on tolerances. Both the rotor and the stator can be molded to the finished shape, with minimal need for post-processing. There will normally only be a need to remove burrs and grind the surfaces that come into contact with each other.

Alternatively, the stator bore can be milled out and the slots turned. The rotor's track can also be turned by simple operations.

No seals are required between rotor and stator. The rotor is fed into the stator until a light touch takes place between the rotor and the stator. According to a particular embodiment, there may even be a small clearance between the rotor and the stator. During operation, a small cushion of fluid will form between the rotor and the stator on which the rotor will float. The rotor therefore does not need to be stored at both ends. This embodiment may be appropriate for special applications. However, the rotor should normally be supported at both ends, so that a minimal - almost zero clearance is achieved between the stator and the rotor to avoid cavitation and recirculation. One of the parts should also be made of a softer material so that the rotor can be pushed further into the stator when worn.

This again means that the only seal that is possibly necessary against rotating parts is around the shaft from the rotor. In some cases, such as in the example in Figure 5, this is not necessary either.

As mentioned earlier, the rotor and stator are designed so that they cannot be brought completely together. Although this is greatly exaggerated in the figures, the purpose of this is that gradually. the rotor and stator wear in the contact surface, the rotor must be able to be guided further into the stator. In this way, the lifetime of the parts can be extended significantly and without any maintenance. This insertion of the rotor can be done manually by adjusting a set screw at regular intervals, but can also be done automatically, for example by the rotor being biased against the stator and fed into it as the parts become worn.

Due to this adaptation according to the degree of wear, the energy converter according to the invention is very insensitive to particles and contaminants in the medium that flows through it. Even if the medium is very abrasive, such as, for example, drilling mud, the lifetime of the energy converter will still be acceptably long.

The above is also one of the most important reasons why the tolerance requirements for manufacturing are very low. Although for a newly manufactured energy converter there may be deviations that cause leaks between rotor and stator, as they are used, the rotor and stator will adapt to each other and provide an increasingly better seal.

The rotor and stator can be manufactured in different materials depending on the area of use. Applicable materials can be steel, aluminum and various types of thermosetting plastics or thermoplastics.

The cross-sectional shape of the tracks 8 and 18 is square in the embodiment shown. However, the shape can also be rounded, triangular or other shapes that are convenient to produce or are optimal in terms of efficiency for the application in question.

It is clear that the stator 1 does not necessarily need to stand still, but can rotate in the opposite direction of the rotor, so that the unit actually has two rotors. Likewise, the inner part can stand still and act as a stator, while the outer part can rotate and act as a rotor.

Claims (14)

1. Energy converter, in particular for use as a hydrodynamic pump, compressor, motor or turbine, comprising a first unit (20) and a second unit (21), characterized in that each unit (20,21), which is known in and of itself, includes a first part (1) with a bore (4), in which at least one helical groove (8) is formed in the wall of the bore (4) and a second part (2) with an outer surface (10), in which at least one helical groove (18) in the outer surface (10), wherein the bore (4) in the first part (1) and the outer surface (10) of the second part (2) are conical with complementary taper, the first (1 ) and the second (2) part is arranged to rotate relative to each other and where at least one of the first (1) or the second (2) part is arranged to be power-coupled to a shaft (3) for withdrawal or supply of rotational torque, and that the shaft from the first unit (20) is power-coupled to the shaft from the second unit (21) so that the first unit (20) is arranged to drive the second e the unit (21). 2. Energy converter according to claim 1, characterized in that the first unit (20) has an inlet (26) for a drive fluid and an outlet for the drive fluid, that the second unit (21) has an inlet (27) for a pump fluid and an outlet (28) ) for the pump fluid and that the outlet from the first unit (20) is in communication with the inlet to the second unit (21), so that drive fluid that has passed through the first unit (20) is arranged to mix with pump fluid that is to flow through the second unit (21). 3. Energy converter according to claim 2, characterized in that the second unit (21) has a larger displacement volume than the first unit (20). 4. Energy converter according to one of the preceding claims, characterized in that the first and second units (20,21) are enclosed by a housing (22), which housing is equipped with an inlet (26) for drive fluid, an inlet (27) for pump fluid and an outlet (28). 5. Energy converter according to one of the preceding claims, characterized in that the at least one groove (8) in the first part (1) has increasing depth from the part of the bore (4) which has the largest diameter (D2) to the part of the bore (4) ) which has the smallest diameter (Dl). 6. Energy converter according to one of the preceding claims, characterized in that the at least one groove (18) in the second part (2) has increasing depth from the part of the rotor (2) which has the smallest diameter (D4) to the part of the rotor (2) ) which has the largest diameter (D3). 7. Energy converter according to one of the preceding claims, characterized in that the bottom of the at least one groove (8,18) lies on an imaginary cylinder surface. 8. Energy converter according to one of the preceding claims, characterized in that the at least one track (8,18) is struck with a pitch that is constant over the length of the first (1) and/or the second part (2). 9. Energy converter according to one of the preceding claims, characterized in that several parallel helical grooves (8,18) are designed in the first (1) and/or the second (2) part. 10. Energy converter according to one of the preceding claims, characterized in that the groove(s) (8) in the first part (1) are turned opposite to the groove(s) (18) in the second part (2). 11. Energy converter according to one of the preceding claims, characterized in that the total flow area for the tracks (8,18) is essentially constant over the length of the first (1) and/or the second (2) part. 12. Energy converter according to one of the preceding claims, characterized in that the second part (2) is a rotor and is stored only at one end. 13. Energy converter according to one of the preceding claims, characterized in that the tracks (8,18) have a pitch of approximately 45°. 14. Energy converter according to one of the preceding claims, characterized in that the tracks (8,18) have a mainly triangular cross-section.