Turbomachine with an adjustable axial impeller arrangement

Abstract

Turbomachine (1) with an adjustable axial impeller arrangement (3), wherein the axial impeller arrangement (3) has a first impeller (4) with a number of first blades (5) arranged along a circumferential edge of the first impeller (4) and a second impeller (6) with a number of second blades (7) arranged along a circumferential edge of the second impeller (6), wherein the first impeller (4) and the second impeller (6) are arranged axially offset from one another along an axial axis (2) and can be driven to rotate concentrically about the axial axis (2), wherein a first blade (5) of the first impeller (4) and a second blade (7) of the second impeller (6) are assigned to one another and form a combined overall blade (8), and wherein the first blade (5) and the second blade (7) of the combined overall blade (8) are adjustable relative to one another, characterized in thatthat the first impeller (4) and the second impeller (6) are displaceable relative to one another via a positive guide (9), wherein the positive guide (9) causes both a relative displacement in an axial direction and a relative displacement in a circumferential direction, so that a blade length l of the combined total blades (8) is thereby changed.

Description

[0001] The invention relates to a turbomachine with an adjustable axial impeller arrangement, wherein the axial impeller arrangement has a first impeller with a number of first blades arranged along a circumferential edge of the first impeller and a second impeller with a number of second blades arranged along a circumferential edge of the second impeller, wherein the first impeller and the second impeller are arranged axially offset from one another along an axial axis and can be driven to rotate concentrically about the axial axis, wherein a first blade of the first impeller and a second blade of the second impeller are assigned to one another and form a combined overall blade, and wherein the first blade and the second blade of the combined overall blade are adjustable relative to one another.

[0002] Turbomachines are known in various designs and are used in numerous applications. A distinction can be made between working machines such as propellers, centrifugal pumps, fans, or compressors, and power machines such as wind turbines, water turbines, and steam turbines. Turbomachines with an axial impeller on which several blades are arranged in the circumferential direction are described, for example, in DE 10 2014 215 817 A1, DE 101 96 771 T5, DE 10 2014 102 311 A1, or EP 0 955 469 B1.

[0003] In most applications, a specified flow rate is required for working machines, which can be generated or delivered by the turbomachine.

[0004] The various components of a controlled system of a driven machine include, for example, the environment, the intake, a pipeline, and components such as heat exchangers and filters, each of which can generate a pressure loss that must be compensated for by the driven machine during operation. A system characteristic curve shows the minimum pressure loss that the fluid machine must generate within the controlled system to achieve or maintain the specified flow rate.

[0005] Determining the system characteristic curve of technical systems can usually only be estimated in advance. Technical systems are often subsequently adjusted, which can cause a change in the system characteristic curve. For a specific application, it is advantageous if a suitable turbomachine can be selected and used that covers the specified flow rate and the resulting pressure loss within the controlled system, while operating close to the optimal operating point for the respective turbomachine. In reality, however, the operation of the turbomachine often has to be subsequently adapted to the controlled system.

[0006] Practical experience has shown various ways to influence and adjust the operation of a turbomachine. Each of these options has its own advantages and limitations, or disadvantages.

[0007] A throttle device allows the volume flow generated by the turbomachine to be easily regulated and adjusted. The use of a throttle device has the advantage of allowing the turbomachine to operate at a fixed speed in an operating mode that is optimal for the turbomachine. However, the throttling process dissipates pressure and thus energy, reducing the system's efficiency.

[0008] It is also known that the speed of the turbo machine can be adjusted, so that subsequent throttling is not necessary. A frequency converter can be used to adjust the speed. This generates a voltage from a three-phase or alternating current that can be varied in terms of amplitude and frequency, which can be used to specify the speed of the turbo machine. By eliminating the need for subsequent throttling, the efficiency of such a system is higher and its operation more efficient. However, the manufacturing costs for a combination of a controllable turbo machine with a frequency converter are significantly higher than for a constantly operated and subsequently throttled turbo machine. Additional effort is often required to ensure the regularly required electromagnetic compatibility of the system.

[0009] Turbomachines with adjustable blades are also known. Depending on the design of the turbomachine and the mounting of the individual blades on an impeller, virtually any adjustment of the blades can be achieved. Turbomachines with adjustable blades are shown and described, for example, in DE 10 2010 011 708 B4.

[0010] A frequently used blade adjustment in practice involves pitch angle control, where pitch angle is the angle between the flow direction of the fluid flowing past the blades and the orientation of a blade profile chord extending from a profile leading edge to a profile trailing edge. By adjusting the pitch angle, a turbomachine can be operated in an efficient operating mode over a comparatively wide range of flow velocities or fluid pressures generated by the turbomachine.

[0011] For example, GB 1085390 A discloses a turbomachine in which the blades are arranged on two impellers arranged one behind the other in the axial direction. The blades can be arranged and aligned on the two impellers in such a way that two associated blades on the two impellers act like a single overall blade in terms of flow technology. The geometry of the overall blade and thus its flow-generating effect is determined by the arrangement and alignment of the two associated blades. This can usually be achieved by pivoting the individual blades on the respective impeller and by adjusting the two impellers in the axial and circumferential directions.In this way, not only a pitch angle but also, for example, a blade length and a curvature of the entire blade can be changed and adjusted in order to adapt and optimize the operation of the turbomachine to individual specifications.

[0012] However, the design effort required for such a blade adjustment capability is considerable. Furthermore, appropriate adjustment of the blade arrangement and alignment typically requires complex manual setup of the turbomachine, which involves considerable installation effort that only seems economically justifiable for high-performance turbomachines. For this reason, such modification and adjustment of the blades is often only provided for comparatively large turbomachines with rotating blade diameters exceeding 2 meters.

[0013] It is therefore considered to be an object of the present invention to design a turbomachine with the features described above in such a way that both its installation and its operation can be carried out as economically as possible.

[0014] This object is achieved according to the invention in that the first impeller and the second impeller can be displaced relative to one another via a positive guide, wherein the positive guide brings about both a relative displacement in an axial direction and a relative displacement in a circumferential direction, such that a blade length of the combined overall blades is thereby changed. It has been shown that by changing the blade length of the combined overall blades, a comparatively simple and yet particularly effective change in the pressure build-up of the fluid flowing through the turbomachine at constant speed is possible. The blade length can be changed simply by suitable adaptation of the arrangement of the two impellers relative to one another, such that no complex pivoting mounting of the individual blades on the first and second impeller is required.The positive guide restricts the relative displacement of the two impellers and limits them to a one-dimensional adjustment option and a change predetermined by the positive guide. Such a limited setup of the turbomachine and its adaptation to individual specifications and requirements through the desired operation of the turbomachine can be carried out easily and without great effort. In many cases, a suitable positive guide also requires no significant additional design and manufacturing effort for a turbomachine designed according to the invention.The forced guidance ensures both an axial distance between the two impellers and an adjustment of the two impellers relative to each other in the circumferential direction, which, despite the forced guidance, enables an individually adjustable change in the blade length and thus a particularly effective adjustment of the operation of the turbomachine at a constant speed.

[0015] The relative displacement of the two impellers to one another can be specified in any desired manner by the forced guidance. For example, a radial displacement relative to one another in the circumferential direction can be specified first, followed by an axial displacement. The order of the displacement directions can also be specified in the reverse order. It is also conceivable for the forced guidance to specify a displacement in the axial direction and in the circumferential direction several times in alternating succession. According to a particularly advantageous embodiment of the inventive concept, the forced guidance brings about a relative displacement in the axial direction and in the circumferential direction simultaneously. The individual blades are aligned by the specified pitch angle such that the profile chord has an angle to an axial plane running parallel to the axial direction.A simultaneous displacement of the two impellers relative to one another in the axial direction and in the circumferential direction caused by the forced guidance can be predetermined such that the two mutually assigned blades are displaced relative to one another along the alignment of the profile chord of the overall blade formed by the two blades, wherein this alignment is determined by a projection of the profile chord relative to a lateral surface concentrically surrounding the two impellers or relative to an axial plane. It can also be expedient for the forced guidance displacement to have a predetermined angle to the alignment of the profile chord of the overall blade, wherein this angle can either be constant or can change in a predetermined manner during the displacement forced by the forced guidance.In this way, a wide range of adjustments of the properties of the overall blade formed by the two associated blades relevant for flow generation can be achieved, with each individual adjustment being predetermined by the positive guidance. By changing the camber in addition to the overall blade length, the characteristic map of the turbomachine, which can be adjusted relative to each other via the positive guidance of the impellers, can be expanded and adjusted over an even wider range.

[0016] It has been shown that a change in the overall blade, which is advantageous for many applications, can be achieved by adjusting the forced guidance by optionally displacing the first impeller relative to the second impeller along a helical line. A forced guidance, which specifies a helical displacement of the two impellers relative to each other, can be easily specified. By helical displacement of the two impellers or the two associated blades relative to each other, a particularly advantageous change in the flow-relevant properties of the overall blade can be achieved and reliably specified without major setup effort.

[0017] Optionally, according to a particularly advantageous embodiment of the inventive concept, the helix runs along a skeleton line of a combined overall blade. The skeleton line of a blade or an overall blade runs along a connecting line of the circle centers inscribed in a blade profile from the profile nose to the profile trailing edge. In an asymmetrically designed blade profile, the skeleton line deviates from the profile chord. By shifting the two impellers relative to each other following the skeleton line, a change in the overall blade and its flow-relevant properties can be specified that is advantageous for certain applications.

[0018] All blades can have a uniform blade profile. It is also possible, and advantageous for many applications, for all blades arranged in the circumferential direction on an impeller to have a uniform blade profile, but for the blades of the first impeller to have a different blade profile than the blades of the second impeller. The two blade profiles can be specified in such a way that a particularly advantageous blade profile of the overall blade can be set for at least one relative arrangement of the two impellers to one another. It is also conceivable for the blade profile of the blades to differ not only between the two impellers, but also for blades with different blade profiles to be arranged along the circumference within an impeller.

[0019] According to a particularly advantageous embodiment of the inventive concept, the mutually facing surfaces of the associated blades of the first impeller and the second impeller each have a constant distance from an imaginary helical surface in an overlapping region, so that during a helical displacement of the first impeller relative to the second impeller along the helical surface, the distance between the mutually facing surfaces in the overlapping region remains constant. The imaginary helical surface runs along the helical displacement of the two impellers, and thus of the respective associated blades arranged on the two impellers, as determined by the positive guidance.Due to a constant distance between the mutually facing surfaces of the two associated blades over the entire overlap area, this distance remains unchanged when the two impellers are displaced relative to each other, which enables a particularly simple design of the characteristic map of the turbomachine covered by the forced displacement and thus a simple and reliable setup of the turbomachine.

[0020] Simple setup and individual adjustment of the turbomachine, as well as its particularly reliable operation under consistent operating conditions, are optionally facilitated by the fact that the first impeller can be positively fixed relative to the second impeller in a predefined relative position. This positive fixation can be achieved, for example, by a locking device that can be locked into several different locking positions, which can fix a relative displacement of the two impellers at several different positions.Instead of a locking device, a manually or automatically operable locking member can also be provided, which can be moved between a displacement position enabling the relative displacement of the two wheels to each other and a locking position blocking the relative displacement in order to release the forced displacement or to fix the two wheels in a predetermined arrangement relative to each other.

[0021] Optionally, it is provided that a preferably radially displaceable locking element and a plurality of recesses are arranged on the first impeller and on the second impeller in such a way that the first impeller can be fixed relative to the second impeller in a relative position predetermined by a positive engagement of the locking element with one of the recesses.

[0022] In order to be able to positively fix the two impellers to one another in any arrangement within the positive guide, independent of individual positions predetermined by recesses or locking engagements, an advantageous embodiment of the inventive concept provides that the first impeller and the second impeller are connected to one another via a threaded engagement in addition to the positive guide. The threaded engagement makes it easy to specify and fix the adjustment of the two impellers to one another within the adjustment range predetermined by the positive guide. For positive fixing, the threaded engagement can be fixed by fixing one threaded element relative to the other threaded element. It is also possible to design the threaded engagement to be self-locking.

[0023] The threaded engagement can be designed or aligned so as to be displaceable in the axial direction of the turbomachine. It is also possible for the threaded engagement to be aligned at an angle between 0 and 90 degrees or perpendicular to the axial direction of the turbomachine, and for the threaded elements to be displaceable relative to each other in this direction.

[0024] According to one embodiment of the inventive concept, the first impeller is manually adjustable relative to the second impeller. Adjusting the impellers relative to each other is typically only necessary once during setup of the turbomachine. The design and manufacturing effort required for a manual adjustment option is comparatively low, enabling a cost-effective design and manufacture of the turbomachine.

[0025] It is also conceivable and optionally possible for the first impeller to be adjustable relative to the second impeller using a drivable actuator. Automated adjustment of the two impellers relative to each other allows particularly convenient adjustment of the two impellers during setup of the turbomachine. Furthermore, automated adjustment of the impellers during operation of the turbomachine is also enabled. Actuator-operated adjustment of the impellers, for example in combination with suitable sensors, also enables closed-loop control of the turbomachine's operation. Due to the positive guidance of the impellers, which can be adjusted relative to each other, actuator-operated adjustment of the two impellers relative to each other can be achieved easily using various actuators and mechanisms.

[0026] According to one embodiment of the inventive concept, the drivable actuator comprises a gear mechanism. A gear mechanism can be used to achieve reliable and precise adjustment of the two wheels relative to each other in a cost-effective manner. The gear mechanism can be adjusted via a stepper motor and fixed in a predetermined position.

[0027] According to one embodiment of the inventive concept, the drivable actuator can be provided with a traveling wave drive. The piezo actuators or sound generators generate resonant vibrations and superimpose them to form waves that typically propagate in the circumferential direction, which then, through frictional engagement, cause the two impellers to move relative to each other. With a traveling wave drive, a very precise adjustment of the two impellers relative to each other is possible, for example, with the help of suitable piezo actuators or sound generators.

[0028] With regard to an embodiment of the inventive concept considered particularly advantageous, it is provided that the drivable actuator has a displaceable pressure piston that is operatively connected to a fluid-filled pressure vessel. With a fluid-actuated adjustment of the impellers, very high actuating forces can be generated and exerted on the two impellers. By appropriately dimensioning the displaceable pressure piston and the pressure vessel, as well as the active surfaces relevant for fluid actuation and in contact with the fluid, an advantageous transmission of the pressure forces can be specified. The pressure required for fluid actuation can be generated using various operating principles or with different actuators. It is also conceivable that the fluid actuation can be carried out manually and, for example, is effected via an elastic pump bag that is connected to the pressure vessel via a valve device.

[0029] An adjustment of the impellers relative to one another that automatically adapts to different operating conditions can optionally be achieved by fluidly connecting the fluid-filled pressure vessel to a first fluid inlet and to a second fluid inlet arranged at a distance in the axial direction. The fluid-filled pressure vessel can be filled with a fluid flowing in through the first fluid inlet or through the second fluid inlet, and can thus be pressurized with a differential pressure relative to the fluid flowing into the turbomachine. The greater the differential pressure between the first fluid inlet and the second fluid inlet of the pressure vessel, the greater the relative adjustment that can be specified between the two impellers.By exploiting a differential pressure within the turbomachine or in an area surrounding the turbomachine, a suitable adjustment of the impellers relative to each other can be specified without a separate or external power supply, thus ensuring efficient operation of the turbomachine. Such adjustment of the turbomachine allows for self-sufficient yet particularly efficient operation of the turbomachine.

[0030] A suitable valve device can fix or influence the adjustment caused by the differential pressure. The valve device can be operated either manually or with automated control or regulation.

[0031] Below, various exemplary embodiments of the inventive concept are explained in more detail, which are schematically illustrated in the drawing. It shows: Fig. 1 a perspective view of a turbomachine with an axial impeller arrangement consisting of two impellers and with blades arranged on the two impellers distributed in the circumferential direction, wherein the two impellers are arranged relative to each other in a first axially contracted operating position, Fig. 2 a perspective view of the Fig. 1, wherein the two impellers are arranged relative to each other in a second axially further spaced operating position, Fig. 3 a schematic representation of a sectional view of two mutually associated blades of a turbomachine with an axially displaceable leading wheel, Fig. 4 a schematic representation of a sectional view according to Fig. 3, wherein the turbomachine has an axially displaceable trailing wheel, Fig. 5 is a schematic representation of a sectional view of two associated blades arranged on different impellers arranged relative to each other in a contracted operating position, Fig. 6 a schematic representation of the two associated blades in a further spaced operating position of the two impellers, Fig. 7 is a schematic sectional view of a turbomachine with two impellers and with blades arranged on the two impellers in a circumferential direction, wherein the two impellers are fixed relative to each other in a predetermined operating position by means of a locking push button, Fig. 8 a schematic side view of the Fig. 7, wherein the two impellers can be fixed relative to each other in several predetermined locking positions for the locking push button, spaced apart in the axial direction, Fig. 9 a schematic sectional view of a differently designed turbomachine in which the two impellers can be fixed at a distance in the axial direction via a threaded engagement with an axially extending threaded rod, Fig. 10 is a schematic sectional view of a turbomachine of a different design, in which an axial displacement of the two impellers relative to each other can be effected by means of an electric motor and a toothed gear, Fig. 11 is a schematic sectional view through a turbomachine in which an axial displacement of an axially adjustable leading wheel relative to an axially fixed trailing wheel can be effected by means of a traveling wave drive, Fig. 12 is a schematic sectional view through a turbomachine in which an axial displacement of an axially adjustable trailing impeller relative to an axially fixed leading impeller can be effected by means of a traveling wave drive, Fig. 13 a schematic sectional view through a differently designed turbomachine, in which an axial displacement of the two impellers relative to each other can be effected by means of a fluid-filled pressure vessel which can be filled and pressurized via a pressure difference occurring in the axial direction of the fluid flowing through the turbomachine.

[0032] In the Fig. 1 and Fig. 2 shows an exemplary embodiment of a turbomachine 1. The turbomachine 1 has an axial impeller arrangement 3 mounted rotatably about an axial axis 2. The axial impeller arrangement 3 in turn has a first impeller 4 with a number of first blades 5 arranged along a circumferential edge of the first impeller 4 and a second impeller 6 with a number of second blades 7 arranged along a circumferential edge of the second impeller 6. The first impeller 4 and the second impeller 6 are arranged axially offset from one another along the axial axis 2 and can be driven to rotate about the axial axis 2. The arrangement and fixing of the turbomachine 1 in a system or the like as well as a drive used for the rotational movement are described in the Fig. 1 and Fig. 2 and not shown in other figures.

[0033] The first impeller 4 and the second impeller 6 are arranged relative to one another both in the axial direction and in the circumferential direction such that a first blade 5 of the first impeller 4 and a second blade 7 of the second impeller 6 are assigned to one another and form a combined overall blade 8. The flow properties of the axial impeller arrangement 3 are therefore not determined primarily by the flow properties of the first blades 5 and the second blades 7 considered in isolation, but rather by the flow properties of the overall blades 8 formed by the two individual blades 5 and 7. The first impeller 4 and the second impeller 6 can be adjusted relative to one another both in the axial direction and in the circumferential direction, which also causes the first blades 5 and the second blades 7 of the combined overall blade 8 to be adjusted relative to one another.In this way, the flow properties of the rotating axial impeller arrangement 3 can be specifically influenced.

[0034] For many applications of a turbomachine 1, it is not necessary for the first blades 5 and the second blades 7 to be adjustable relative to one another in any desired direction along the axial axis 2, in any desired direction in the circumferential direction, and in any desired orientation relative to the axial axis 2. The effort required for such a complex adjustment of all individual blades is comparatively high and can often only be carried out by trained specialist personnel. Therefore, the invention provides that the first impeller 4 and the second impeller 6 are connected to one another by a Fig. 1 and Fig. 2, which is not shown in detail and is only indicated by an arrow, are displaceable relative to one another. The forced guidance 9 causes both a relative displacement in an axial direction and a relative displacement in a circumferential direction, thereby changing a blade length l of the combined total blades 8.

[0035] The positive guide 9 can be achieved by any operative connection between the two wheels 4, 6 and, for example, by a positive engagement of a suitable formation in a groove. It is also conceivable for the positive guide 9 to have a guide rail or a guide surface, or several guide rails or guide surfaces, along which a formation is positively guided, thereby predetermining a displacement of the two wheels 4, 6 relative to each other.

[0036] In Fig. 1, the two impellers 4, 6 of the turbomachine 1 are arranged relative to one another in a first axially contracted operating position, in which the first and second blades 5, 7 overlap over a larger axial area. The blade length l of the combined blades 8 formed by the first and second blades 5, 7 has a length l1 in the axially contracted operating position. The positive guide 9 forces a helical displacement of the two impellers 4, 6 relative to one another upon adjustment of the two impellers 4, 6 relative to one another, with a helical line of the helical displacement running along a skeleton line of a combined overall blade 8. Due to the positive guide, such an adjustment of the two impellers 4, 6 relative to one another essentially corresponds to a one-dimensional relative movement, which can be carried out without great effort, both manually and automatically. Fig. 2, the two impellers 4, 6 of the turbomachine 1 are arranged relative to one another in a second and axially further spaced operating position. The blade length l of the total blades 8, which is formed by the blades 5, 7 spaced further apart along the axial axis 2, has a length l2, wherein the length l2 is greater than the length l1. In this way, the blade length l of the total blades 8 and thus the fluidic properties of the turbomachine 1 can be influenced and changed by adjusting the two impellers 4, 6 relative to one another in a very simple and uncomplicated manner thanks to the positive guide 9.

[0037] In the Fig. 3 and Fig. 4 shows highly simplified sectional views through an entire blade 8. The entire blade 8 is formed by a first blade 5, which is fixed to a first impeller 4, and by a second blade 7, which is fixed to a second impeller 6. The two impellers 4, 6 are shown in the Fig. 3 and Fig. 4 is not shown. For a displacement of the two impellers 4, 6 relative to each other, it is fundamentally possible for either the first impeller 4, which is the first to be flowed against in the flow direction and can also be referred to as the leading impeller, to be displaced via the forced guide 9, while the second impeller 6, which is the next to be flowed against in the flow direction and can also be referred to as the trailing impeller, is fixed in the axial direction. Such a configuration of a turbomachine 1 with an axially adjustable leading impeller or first impeller 4 is shown in Fig. 3. A sectional view through the two blades 5, 7 in a turbomachine 1 with an axially adjustable first impeller 4 relative to an axially fixed second impeller 6 is shown in Fig. 3 and in further figures designated by A. It is also conceivable that the second impeller 6, which is arranged behind the first impeller 4 in the flow direction, is mounted so as to be adjustable in the axial direction and can be adjusted via the positive guide 9, while the first impeller 4 is fixed in the axial direction. A sectional view through the two blades 5, 7 in a turbomachine 1 with an axially adjustable second impeller 6 is shown in Fig. 4 and is designated B there and in other figures.

[0038] The two mutually associated blades 5, 7 can be designed in an overlapping region 10 with regard to their shape such that mutually facing surfaces 11, 12 of the mutually associated blades 5, 7 of the first impeller 4 and the second impeller 6 in the overlapping region 10 each have a constant distance from one another or from an imaginary helical surface, so that in the case of a helical displacement of the first impeller 4 relative to the second impeller 6 along the helical surface, a distance between the mutually facing surfaces 11, 12 in the overlapping region 10 is constant.Due to the relative arrangement of the two impellers 4, 6 to one another and due to the positive guide 9, a gap 13 is formed between the two blades 5, 7 over an axial adjustment range of the two impellers 4, 6, which gap can be specified to be constant regardless of a respective adjustment position and can be designed to be comparatively narrow, so that neither the gap 13 nor the profile noses 14 and profile trailing edges 15 located in a central region of the overall blade 8 have an excessively adverse effect on the flow properties of the overall blade 8.

[0039] In the Fig. 5 and Fig. 6 also shows sectional views through an overall blade 8, which is formed by two mutually associated blades 5, 7. The two blades 5, 7 each have a schematically indicated blade profile. By adjusting the two blades 5, 7 relative to each other, which is achieved by a Fig. 5 and Fig. 6 is predetermined and limited by a forced guide 9 not shown, both the blade length l and a blade curvature c can be influenced and changed, wherein the blade curvature c denotes the greatest distance of a skeleton line of the entire blade 8 from a profile chord of the entire blade 8.

[0040] In Fig. Figure 7 shows a schematic sectional view through a turbomachine 1, wherein the first impeller 4 can be displaced relative to the second impeller 6 via the positive guide 9 (not shown in detail). The two impellers 4, 6 can be positively secured in a predetermined relative position by a spring-loaded push button 17 that projects radially outward and engages in a recess 16 adapted thereto. The push button 17 forms a positively engaging locking element, with which the two impellers 4, 6 are locked and secured relative to one another.

[0041] In Fig. 8 is a schematic side view of the Fig. 7, wherein the side view shows the turbomachine 1 in the circumferential direction from a different viewing direction. Along a helical line defined by the positive guide 9, several recesses 16 are formed so that the two impellers 4, 6 can be positively fixed in several different relative positions to each other. Fig. 7 and Fig. The turbomachine 1 shown in Fig. 8 has an axially displaceable first impeller 4, which is also indicated by the section line AA through the two blades 5, 7, which basically correspond to a Fig. 3 and designated A.

[0042] At the Fig. In the embodiment of the turbomachine 1 schematically illustrated in Figure 9, the second impeller 6 has a hollow shaft 18 in which a screw 19 is mounted, which is fixed to the first impeller 4 in the axial direction. The screw 19 engages with the second impeller 6 via a threaded engagement 20. By rotating the screw 19 projecting on an end face 21 of the hollow shaft 18 facing away from the first impeller 4, an axial displacement of the first impeller 4 relative to the second impeller 6 can be effected. Fig. 9 not shown, a displacement of the two impellers 4, 6 and thus of the two associated blades 5, 7 relative to each other in the circumferential direction is also specified.

[0043] At the Fig. In the exemplary embodiment of a turbomachine shown in Figure 10, an axial displacement of the two impellers 4, 6 is effected by an electric motor 22 with a spur gear 23, wherein the spur gear 23 is in engagement with a gear ring 24 extending both in the circumferential direction and in the axial direction. When the electric motor 22 is actuated, the Fig. 10 not shown in detail, causes an adjustment of the two impellers 4, 6 in the axial direction as well as in the circumferential direction.

[0044] In the Fig. 11 and Fig. 12 shows two different variants of a turbomachine 1, in which the displacement of the two impellers 4, 6 is effected by a schematically indicated traveling wave drive 26. While in the Fig. 11, the first impeller 4 can be axially displaced relative to the axially fixed second impeller 6, in the embodiment shown in Fig. 12, the second impeller 6 is axially displaced relative to the axially fixed first impeller 4.

[0045] In Fig. Figure 13 merely schematically illustrates an embodiment of a turbomachine 1, in which the second impeller 6 forms a displaceable pressure piston 27, which is operatively connected to a fluid-filled pressure vessel 28 formed in the first impeller 4. In this way, a hydraulically actuated displacement of the two impellers 4, 6 can be effected.

[0046] In the Fig.In the embodiment shown in Figure 13, the fluid-filled pressure vessel 28 is fluid-conductingly connected to a first fluid inlet 29 and to a second fluid inlet 30 arranged at a distance in the axial direction, wherein the fluid-filled pressure vessel 28 can be filled with a fluid flowing in through the first fluid inlet 29 or through the second fluid inlet 30. The fluid can be the fluid flowing through the turbomachine 1, such as air or a liquid. Due to the differential pressure that develops between the two fluid inlets 29 and 30 arranged at a distance along the axial axis 2 during operation of the turbomachine 1, a fill level and a pressurization of the fluid-filled pressure vessel 28 can be predetermined without the need for an external energy supply. If necessary, the fluid-filled pressure vessel 28 can be equipped with a pressure booster (not shown).A filling level and an impeller adjustment pressure of the fluid in the fluid-filled pressure vessel 28 can be specified via valve devices 31, 32.

Claims

[1] Turbomachine (1) with an adjustable axial impeller arrangement (3), wherein the axial impeller arrangement (3) comprises a first impeller (4) with a number of first blades (5) arranged along a circumferential edge of the first impeller (4) and a second impeller (6) with a number of second blades (7) arranged along a circumferential edge of the second impeller (6), wherein the first impeller (4) and the second impeller (6) are arranged axially offset from one another along an axial axis (2) and can be driven in rotation concentrically about the axial axis (2), wherein a first blade (5) of the first impeller (4) and a second blade (7) of the second impeller (6) are assigned to one another and form a combined overall blade (8), and wherein the first blade (5) and the second blade (7) of the combined overall blade (8) are adjustable relative to one another, characterized byin that the first impeller (4) and the second impeller (6) are displaceable relative to one another via a positive guide (9), wherein the positive guide (9) effects both a relative displacement in an axial direction and a relative displacement in a circumferential direction, so that a blade length l of the combined total blades (8) is thereby changed. [2] Turbomachine (1) according to claim 1, characterized by that the forced guidance (9) simultaneously causes a relative displacement of the two impellers (4, 6) in the axial direction and in the circumferential direction. [3] Turbomachine (1) according to claim 1 or claim 2, characterized by that the first impeller (4) is displaceable relative to the second impeller (6) along a helical line. [4] Turbomachine (1) according to claim 3, characterized by that the screw line runs along a skeleton line of a combined overall blade (8). [5] Turbomachine (1) according to one of the preceding claims, characterized by that the mutually facing surfaces (11, 12) of the mutually associated blades (5, 7) of the first impeller (4) and the second impeller (6) each have a constant distance from an imaginary helical surface in an overlapping region (10), so that when the first impeller (4) is displaced helically relative to the second impeller (6) along the helical surface, a distance between the mutually facing surfaces (11, 12) in the overlapping region (10) is constant. [6] Turbomachine (1) according to one of the preceding claims, characterized by that the first impeller (4) can be fixed in a form-fitting manner relative to the second impeller (6) in a predeterminable relative position to one another. [7] Turbomachine (1) according to claim 6, characterized bythat a preferably radially displaceable locking element and a plurality of recesses (16) are arranged on the first impeller (4) and on the second impeller (6) in such a way that the first impeller (4) can be fixed relative to the second impeller (6) in a relative position predetermined by a positive engagement of the locking element with one of the recesses (16). [8] Turbomachine (1) according to claim 6, characterized by that the first impeller (4) and the second impeller (6) are connected to each other via an axially displaceable threaded engagement in addition to the positive guide (9). [9] Turbomachine (1) according to one of the preceding claims, characterized by that the first impeller (4) is manually adjustable relative to the second impeller (6). [10] Turbomachine (1) according to one of the preceding claims 1 to 8, characterized bythat the first impeller (4) is adjustable relative to the second impeller (6) with a drivable actuator. [11] Turbomachine (1) according to claim 10, characterized by that the drivable actuator has a toothed gear. [12] Turbomachine (1) according to claim 10, characterized by that the drivable actuator has a traveling wave drive (26). [13] Turbomachine (1) according to one of the preceding claims 1 to 8, characterized by that the drivable actuator has a displaceable pressure piston (27) which is in operative connection with a fluid-filled pressure vessel (28). [14] Turbomachine (1) according to claim 13, characterized bythat the fluid-filled pressure vessel (28) is fluid-conductingly connected to a first fluid inlet (29) and to a second fluid inlet (30) arranged at a distance in the axial direction, and that the fluid-filled pressure vessel (28) can be filled with a fluid flowing in through the first fluid inlet (29) or through the second fluid inlet (30) and can thereby be pressurized with a differential pressure relative to the fluid flowing to the turbomachine (1).

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