Technical Field

The invention concerns a bladeless fluid machine comprising a stator in which a bladeless rotor of a rotationally symmetrical shape is axially mounted while between the stator and the rotor there is a coaxial channel and the stator is equipped with at least one fluid inlet and at least one fluid outlet and the fluid outlet is positioned away from the fluid inlet in the direction of the axis of the bladeless rotor.

Background Art

Czech patent no. CZ 284483 and the international application no. PCT/CZ97/00034, published under no. WO 98/17910, the disclosure of which is incorporated by reference, concern a bladeless fluid machine that has a bladeless rotor of a rotationally symmetrical shape installed in the stator. The bladeless rotor is installed in the stator in such a way that when fluid enters the stator, the rotor deflects from the central position, touches the inner wall of the stator and starts to roll along the inner wall of the stator with a circular movement.

The hydraulic motor for driving mechanical tools described in Czech utility model no. 7606 and in international application PCT/CZ98/00013, published under no. WO 99/61790, the disclosure of which is incorporated by reference, is also based on the same principle. This hydraulic motor is also equipped with a bladeless rotor installed in a stator in such a way that when fluid enters the stator, the rotor deflects from the central position, touches the inner wall of the stator and starts to roll along the inner wall of the stator in a circular way.

A common disadvantage of the above-mentioned embodiments is that the bladeless rotor cannot be attached to an axially positioned rigid shaft as such a simple installation would not make it possible for the rotor to deflect from the central position and to roll on the inner wall of the stator. Author's certificate no. 941 665 of the former USSR discloses a hydraulic motor that consists of a guiding channel in which a confusor is created. In the axis of the confusor a ball rotor is installed on a shaft. The rotor is connected to a starting motor.

In the stage of actuation, first of all the starting motor is used to rotate the shaft and the ball rotor consequently. This way the stream of liquid that flows around the ball in the confusor on all sides starts rotating. The stream of liquid rotating in the confusor then maintains the rotation of the ball rotor due to friction between the liquid and the surface of the ball rotor.

However, the disadvantage of this model is that the hydraulic motor cannot be actuated without a starting motor.

Another author's certificate, no. 1701971 , of the former USSR describes a similar hydraulic motor where the starting motor is replaced with screw blades installed in the confusor.

Also, in the case of this model the hydraulic motor cannot be actuated without an auxiliary starting device, comprising screw blades in this case.

Disclosure of Invention

The above mentioned shortcomings are solved by a bladeless fluid machine comprising a stator in which a bladeless rotor of a rotationally symmetric shape is axially mounted in a rotating way and a coaxial channel between the stator and the rotor. The stator is equipped with at least one fluid inlet and at least one fluid outlet while the fluid outlet is positioned away from the fluid inlet in the direction of the axis of the bladeless rotor. The principle of the invention is that the fluid inlet is oriented tangentially to the stator and that the coaxial channel has the shape of a diffuser at least in part of its length. The advantage of a bladeless fluid machine based on this invention is that it does not need any auxiliary rotating drive and in spite of this it can have simple rotor mounting. A coaxial channel with the shape of a diffuser allows optimum utilization of energy of the entering fluid.

In a preferred embodiment, the fluid inlet comprises of a nozzle that can be preferably provided with direction control and/or flow regulation.

In a preferred embodiment, the bladeless rotor is mounted onto a rigid shaft.

It is also useful if the bladeless rotor has an elongated shape and its diameter decreases in the direction from the fluid inlet to the fluid outlet.

Brief Description of Drawings

The invention will be described in detail with the use of drawings where fig. 1 schematically presents the first embodiment of a bladeless fluid machine based on the invention. Fig. 2 shows another embodiment of a bladeless fluid machine based on the invention. Fig. 3 presents the embodiment according to fig. 2 in an axial view. Figs. 4 through 13 schematically present various shapes of rotors and stators and coaxial channels consequently.

Modes for Carrying Out the Invention

The bladeless fluid machine according to fig. 1 has a stator 1 of a cylindrical shape. In the stator 1 a bladeless rotor 2 of a rotationally symmetrical shape is mounted on a rigid shaft 3. Between the stator 1 and the rotor 2 there is a coaxial channel 7 ensuring free flow of fluid. The ends of the shaft 3 are mounted in the stator 1 in bearings 6, so the bladeless rotor 2 is fixed to the stator 1 in a pivoted way.

For the needs of this invention, the term "bladeless rotor of a rotationally symmetrical shape" means a body which has an axis of rotation, which is simultaneously its axis of symmetry, i.e. on all planes passing through the axis of symmetry the section of the rotor is the same. Of course, the generatrix the rotation of which determines the shape of the outer surface of the rotor can in principle have any shape.

The stator 1 is equipped with a tangentially oriented fluid inlet 8 at one end and a fluid outlet 5 at the other end. It is obvious that there may be several fluid inlets 8 as well as fluid outlets 5. In the embodiment presented in fig 1 there is one fluid inlet 8 comprising one tangentially oriented nozzle 4 while there are several fluid outlets 5. In this embodiment the fluid outlets 5 are arranged both in the front wall of the stator 1 and in the shell of the stator 1 near the above-mentioned front wall of the stator 1.

In the embodiment according to fig. 1 the bladeless rotor 2 has the shape of a truncated cone and as the inner surface of the stator 1 has a cylindrical shape, a coaxial channel 7 is formed between the stator 1 and rotor 2. The coaxial channel 7 gets wider in the flow direction of the fluid and this way it creates a diffuser since the angle α of inclination of the shell of the stator 1 is zero and the angle β of the inclination of the shell of the rotor 2 has positive values (see fig. 4).

The bladeless rotor 2 with the shape of a truncated cone is installed in the stator 1 in such a way that the largest diameter of the bladeless rotor 2 is arranged at the side of the fluid inlet 8 and the smallest diameter of the bladeless rotor 2 is at the side of the fluid outlet 5.

The nozzle 4 of the fluid inlet 8 enters the stator 1 tangentially in a place between the largest diameters of the bladeless rotor 2 and the adjacent front wall of the stator 1.

The nozzle 4 can be equipped with a control of direction of the nozzle 4 and/or regulation of fluid flow through the nozzle 4 (not shown in the drawing). There are several structural arrangements of directional control of nozzles and well as regulation of fluid flow through nozzle that are generally well-known and this is why these elements will not be described in detail.

In the embodiment according to the invention it is possible to turn the nozzle in the range of up to 45° in all directions.

Pressure fluid entering the stator 1 through the fluid inlet 8 travels tangentially along the inner wall of the stator 1 while it gradually enters the coaxial channel 7 between the stator 1 and the rotor 2, turns the rotor 2 and subsequently leaves the stator 1 through the fluid outlets 5. The coaxial channel 7 with the shape of a diffuser ensures optimum utilization of energy of the flowing fluid as in the diffuser boundary layers are advantageously created that significantly participate in executing the characteristic phenomenon the principle of which is explained with the use of the mathematical formulas presented below.

Fluid flow between the shell of the rotor 2 and the inner wall of the stator 1 is modelled mathematically by a system of formulas for viscous compressible flow consisting of the continuity formula, Navier-Stokes formulas and the energy formula. These formulas result from the laws of conservation of continuity, motion quantity and energy.

For three-dimensional flow this system can be described as follows:

For symmetric three-dimensional flow this system can be described as follows:

During practical tests, measurements of the bladeless fluid machine according to fig 1 were carried out. The cylindrical stator 1 of the machine had the external diameter of 41 mm and the internal diameter of 34.5 mm. The largest diameter of the used bladeless rotor 2 with the shape of a truncated cone was 33 mm while its smallest diameter was 29.8 mm and its length was 32 mm. The fluid used was pressurized air from a pressure vessel in which the pressure was maintained within the range of 380 to 420 kPa. With the use of pressure regulation (not shown) of the nozzle 4 the speed of the rotor 2 in the range of 2,800 to 3,650 rpm was achieved while the motor power was in the range of 135 to 270 W.

In the above-mentioned example, air was used as the driving fluid, but all fluids can be used in general.

The bladeless fluid machine according to fig. 2 (side view) and fig. 3 (axial view) only differs from the embodiment shown in fig. 1 by the fact that the stator 1 does not have a cylindrical shape, but has the shape of a truncated cone like the rotor 2. However, even in this case the coaxial channel 7 forms a diffuser as the inclination angle α of the shell of the stator 1 is smaller than the inclination angle β of the rotor 2 shell (see also fig. 5). Figs. 2 and 3 indicate that the position of the nozzle 4 can be adjusted in all direction.

The function of the bladeless fluid machine according to figs. 2 and 3 is the same as in the case of the above-mentioned embodiment shown in fig. 1.

Of course, the bladeless rotor 2 does not need to have the shape of a truncated cone only as in the embodiments presented in figs. 1 through 3. The only condition is that the shape of the bladeless rotor must be rotationally symmetrical.

It is generally advantageous for the bladeless rotor 2 to have an elongated shape and for its diameters to get smaller in the direction from the fluid inlet 8 to the fluid outlet 5. However, as the embodiments presented in fig. 6 and 7 show, other versions are also possible. But the stator 1 must have such a shape that the coaxial channel 7 can form a diffuser at least in part of its length.

Figs. 6 through 13 show other examples of possible shapes of the stator 1 and rotor 2.

In the embodiment shown in fig. 6 the rotor 2 has a cylindrical shape and the stator 1 has the shape of a cone whose diameter gets wider in the flow direction. It means that the coaxial channel between the rotor 2 and stator 1 forms a diffuser.

In the embodiment according to fig 7 both the rotor 2 and the stator 1 have the shape of a cone whose diameter gets wider in the flow direction. However, the inclination angle α of the shell of the stator 1 is bigger than the inclination angle β of the shell of the rotor 2, which means that the coaxial channel between the rotor 2 and stator 1 forms a diffuser.

The embodiment shown in fig. 8 is similar to the embodiment in fig. 5 while the embodiment in fig. 8 differs from the embodiment in fig. 5 by the fact that the stator 1 has the form of a narrowing cone only in part of its length while at the end it has a cylindrical shape. This means that the coaxial channel 7 between the rotor 2 and stator 1 forms a diffuser only in part of its length, which is, however, sufficient for the function of the machine.

The embodiment in fig. 9 only differs from the embodiment in fig. 8 by the fact that it is not only the stator 1 that has a cylindrical ending, but also the rotor 2. It means that the coaxial channel 7 between the rotor 2 and stator 1 forms a diffuser only in part of its length.

In the embodiments shown in figs. 10 and 11 the first section (related to the flow direction) of the coaxial channel 7 between the rotor 2 and stator 1 has the shape of a confusor and it is only the continuing part of the coaxial channel 7 that has the shape of a diffuser. As we have mentioned, it is sufficient for the function of a bladeless fluid machine if the coaxial channel 7 has the shape of a diffuser at least in part of its length.

The above-mentioned sample embodiments of a bladeless fluid machine according to the invention we have described stators 1 and rotors 2 with a rotational shape the generatrix of which were straight lines or broken straight lines. Naturally, the generatrix the rotation of which determines the shape of the outer surface of the rotor 2 or the inner surface of the stator 1 can have any shape, both convex and concave. Examples of such embodiments are shown in figs. 12 and 13. The only condition is that the coaxial channel 7 must have the shape of a diffuser at least in part of its length.