Centrifugal pump assembly with rotatable valve

Abstract

The invention relates to a centrifugal pump assembly comprising: an electric drive motor (2); at least one impeller (18) driven by said motor; and a pump housing (6) surrounding the impeller (18), said pump housing comprising at least one intake connection (20) and at least two pressure connections (22, 24), the pump housing (6) containing a rotatable valve element (30, 30', 30'') which can be moved between at least two selection positions in which the flow paths through the at least two pressure connections (22, 24) are open to differing extents. The valve element (30, 30', 30'') has an annular wall (32) surrounding the impeller (18), at least one selection opening (48) being formed in said wall, and the valve element (30, 30', 30'') is rotatably mounted in the interior of the pump housing (6) about an axis of rotation (X) that is central relative to the annular wall (32).

Description

[0001] The invention relates to a centrifugal pump unit with a valve element arranged in a pump housing of the centrifugal pump unit.

[0002] Centrifugal pump units typically have at least one impeller driven by an electric motor. The impeller rotates within a pump housing, enabling it to pump fluid from a suction port to at least one discharge port. Centrifugal pump units are also known in which a valve element is integrated into the pump housing. Such a valve element allows the flow to be selectively directed to one of two discharge ports, depending on its position. US 2004 / 0173249 A1 discloses a pump unit for a dishwasher, which has a valve element surrounding the pump impeller. The valve element is rotatable between two positions by a motor.The valve element also has movable sealing surfaces which can be brought into contact with the surrounding area of ​​the openings to be closed by the fluid pressure generated by the impeller. US 2004 / 0071547 A1 and US 4,869,076 disclose pump units with valve elements which selectively open two different outlet openings depending on the direction of rotation of the pump unit. With these pump units, opening a specific outlet opening requires operating the pump unit in the corresponding direction of rotation, meaning that the impeller blade design cannot be optimized for a single direction of rotation. Further centrifugal pump units according to the prior art are known from documents US 5,924,432 A and EP 3,376,050 A1, the latter falling under Article 54(3) EPC.

[0003] The object of the invention is to improve the valve assembly in such a centrifugal pump unit with regard to function and design. This object is achieved by a centrifugal pump unit with the features specified in claim 1. Preferred embodiments are described in the dependent claims, the following description, and the accompanying figures.

[0004] The centrifugal pump assembly according to the invention comprises an electric drive motor which rotates at least one impeller of the centrifugal pump assembly. The electric drive motor is preferably a canned motor or a wet-running electric drive motor. The impeller is arranged in the pump housing surrounding it. The pump housing has a suction port which is connected to a suction inlet of the impeller. Furthermore, the pump housing has at least two pressure ports. The two pressure ports can, for example, serve to selectively direct the flow generated by the impeller into two different circuits of a heating system, such as a heating circuit or a heat exchanger for domestic hot water heating.A rotatable valve element is arranged in the pump housing, which can be moved between at least two switching positions in which the flow paths through the at least two pressure ports are open to different degrees. Particularly preferably, in a first switching position, a flow path through a first pressure port is open, while a flow path through the second pressure port is closed. Similarly, in a second switching position, the flow path through the first pressure port is preferably closed and the flow path through the second pressure port is open. In this way, the valve element can function as a changeover valve.

[0005] According to the invention, the valve element has an annular wall surrounding the impeller, in which at least one switching opening is formed. This switching opening can be moved into different positions or switching states by rotating the valve element in order to open the flow paths differently as described above. The valve element is rotatably mounted inside the pump housing about an axis of rotation concentric with the annular wall. The annular wall in the area surrounding the impeller has the advantage that it can simultaneously serve to guide the flow. Furthermore, a flow generated by the impeller can act directly on the annular wall to rotate the valve element about the axis of rotation depending on the flow. In this way, the flow generated by the impeller can be used to move the valve element from one switching state to another.

[0006] According to a preferred embodiment of the invention, at least one, preferably two, outlet openings connected to the pressure ports are located in a wall of the pump housing facing the annular wall. These outlet openings can be at least partially overlapped with the at least one switching opening, depending on the switching position of the valve element. Particularly preferably, a switching opening can be selectively overlapped with one of the two outlet openings to implement a switching function between the two outlet openings by rotating the valve element. Alternatively or additionally, a change in flow rate can also be achieved by overlapping the switching opening with at least one outlet opening to varying degrees.

[0007] According to a further preferred embodiment of the invention, the valve element has a wall extending transversely to the axis of rotation inside the annular wall, which preferably surrounds a suction inlet of the impeller. This wall thus forms a base surface inside the annular wall. The wall can, in particular, connect the annular wall to a bearing for the valve element. Furthermore, the wall can serve as a surface for the flow generated by the impeller, so that the flow can rotate the valve element between its switching positions. The wall is more preferably designed as an annular surface that surrounds the suction inlet of the impeller in a ring-like fashion. The suction inlet is preferably located centrally in the wall. This wall can thus more preferably separate the suction side and the pressure side inside the pump housing.

[0008] The ring wall preferably has a circular outer contour, and particularly preferably a cylindrical or conical outer contour. This design has the advantage that, when the valve element rotates, the ring wall can preferably move at a constant distance parallel to an inner wall of the pump housing.

[0009] Preferably, the valve element is rotatably mounted on a fixed component inside the pump housing. This fixed component can be formed integrally with the pump housing or be fixed to it in a rotationally rigid manner. This creates an independent mounting for the valve element.

[0010] According to a further preferred embodiment of the invention, the at least one switching opening is completely surrounded at its edge by at least one section of the ring wall. That is, the switching opening is designed as a hole or opening in the ring wall. Because the switching opening is surrounded by a preferably closed edge, a sealing or contact surface can be created in the circumferential region of the switching opening. Furthermore, the ring wall can have a continuous closed edge at its free end, which can be brought into contact with a wall of the pump housing for sealing purposes. The free end of the ring wall is preferably the axial end that faces away from the end where the wall extending transversely to the axis of rotation is located.

[0011] Preferably, the ring wall extends in a direction transverse to its circumference at an angle of less than 90° and preferably less than 45° to the axis of rotation of the valve element. This results in a cylindrical or preferably conical shape for the ring wall. Such a shape has the advantage that at least sections of the ring wall can be brought into good contact with an inner wall of the pump housing for sealing purposes.

[0012] According to the invention, the entire valve element is movable between a closed position, in which the valve element frictionally engages a contact surface in the pump housing, and a disengaged position, in which the valve element is movable relative to the contact surface. The valve element and the contact surface can thus function as a coupling, which serves to hold the valve element in a selected switching position. The movement of the valve element is preferably effected by the fluid pressure generated by the impeller. In this way, a pressure-dependent coupling can be created, which, depending on the operating conditions of the drive motor, can be engaged and disengaged solely by the pressure build-up in the pump housing.The connection between the valve element and the mating surface can be achieved solely by friction or, optionally, additionally by positive locking through engagement elements arranged on the valve element and / or the mating surface. To rotate the valve element from one switching position to another, it is first moved into its released position, preferably by reducing the pressure in the pump housing or in the pressure chamber surrounding the impeller. Such a pressure reduction can be achieved by reducing the speed of the drive motor or by switching off the drive motor.

[0013] The valve element is designed such that its contact with the contact surface holds it in its selected switching position. The entire valve element, as described below, thus functions as a friction-fit coupling, which, in the engaged position, serves to fix the valve element in a selected switching position and to prevent movement to the other switching position. In the released position, the valve element is free to move between the switching positions.

[0014] Preferably, at least one movable section can be designed as an elastic edge section of the ring wall. Even more preferably, the entire ring wall is elastically designed so that it can preferably be deflected radially outwards by pressure prevailing inside the ring wall. An elastic design of the wall section can generate restoring forces which preferably return the movable section automatically to its original position when the applied pressure is removed.

[0015] According to the invention, the entire valve element is movable in a direction transverse to its direction of rotation and parallel to its axis of rotation between a released and a closed position. The direction of movement of the valve element between the released and closed positions is thus different from the direction in which the valve element moves between switching positions. This allows movement between switching positions to be achieved independently of the valve element's fixed position. To enable movement of the valve element in the direction of its axis of rotation, the valve element is preferably mounted so as to be axially displaceable on the axis of rotation.

[0016] Preferably, the valve element and the pump housing are designed such that, in the engaged position, at least a section of the valve element rests against an inner wall of the pump housing. In this way, the inner wall of the pump housing forms a contact surface and, together with the section of the valve element, the coupling described above. Such a coupling can be implemented in this way with very few components. Essentially, no additional components beyond the valve element and the existing pump housing are required.

[0017] Preferably, the valve element is designed and arranged such that a pressure prevailing in the circumferential region of the impeller acts on the valve element in such a way that the entire valve element is moved into the closed position. More preferably, the pressure prevailing in the circumferential region of the impeller holds the valve element in fixed contact with a contact surface, in particular an inner wall of the pump housing. Thus, the pressure in the circumferential region of the impeller holds the valve element in its closed position and fixes it in the achieved switching position. The pressure in the circumferential region of the impeller is generated by the impeller during its rotation. The described coupling, which is formed by the contact of the valve element with a contact surface, can therefore be engaged by the pump unit without any additional actuating means.This creates a coupling that can be engaged and disengaged solely by controlling the drive motor.

[0018] Furthermore, a force-generating means is provided, particularly preferably in the form of a spring, which exerts force on the valve element from the engaged position towards the disengaged position. This ensures that when the pressure in the pressure chamber on the outlet side of the impeller falls below a predetermined value, the valve element automatically returns to its initial or rest position, which corresponds to the disengaged position. This creates a coupling that automatically disengages when the pressure drops. That is, by increasing the pressure in the pressure chamber, the coupling can be moved into its engaged position. It can be disengaged again by reducing the pressure. For this purpose, it is preferred that the control of the drive motor and / or the design of the drive motor and the force-generating means are coordinated so that at a specific speed of the drive motor, or...At a certain output pressure, the force of the force-generating means is overcome to bring the valve element into the closed position. Conversely, the force-generating means is preferably dimensioned such that when a certain rotational speed or output pressure is undershot, it reliably moves the valve element back into the released position.

[0019] According to a particularly preferred embodiment of the invention, a flow-guiding element, preferably spirally shaped, leading to the at least one switching opening, can be located on the inner circumference of the ring wall. This creates a spiral channel in the circumferential region of the impeller leading to the switching opening and thus to the outlet, which preferably rotates together with the valve element when the latter is moved between its switching positions. This ensures optimal flow guidance towards the outlet at all times, regardless of the switching position of the valve element.

[0020] The valve element is particularly preferred as a molded part made of metal or plastic, especially as an injection-molded plastic part. This enables cost-effective manufacturing and, at the same time, the possibility of easily creating complex geometries, such as flow paths within the valve element.

[0021] According to another possible embodiment of the invention, the valve element has a bearing sleeve at its center, which rotatably slides on a fixed bearing pin in the pump housing. The bearing pin can be formed integrally with the pump housing or be a separate component fixed within the pump housing. The bearing sleeve is preferably formed integrally with the other sections of the valve element. Preferably, the bearing sleeve is designed such that a closed bearing chamber is formed between the bearing sleeve and the bearing pin, allowing for permanent lubrication or pre-lubrication within this chamber, thereby ensuring smooth rotation of the valve element on the bearing pin.Alternatively or additionally, lubrication of the bearing by the conveyed fluid can be provided, whereby the bearing gap between the bearing sleeve and the bearing pin is preferably protected against penetrating contaminants in order to ensure permanently smooth operation.

[0022] According to another possible embodiment of the invention, the valve element can be rotatably mounted on an inlet nozzle located in the pump housing and engaging with a suction port of the impeller. This arrangement creates an annular bearing surface surrounding the suction port. This arrangement has the advantage that the interior of the suction port and the suction nozzle can remain free of bearing elements, thus ensuring low flow resistance in the suction area of ​​the impeller. Simultaneously, a seal can be created between the valve element and the suction port, allowing the valve element to separate a suction-side chamber from a pressure-side chamber inside the pump housing.

[0023] Preferably, a return element can be provided which acts on the valve element in its direction of rotation. The return element is preferably designed such that, when the impeller is stationary, it moves the valve element into a predetermined initial position, which preferably corresponds to one of the possible switching positions. Such a return element can, for example, be a spring or a magnetically actuated return element. Particularly preferably, the valve element is designed such that it causes a return movement by gravity; that is, the return element is designed as a weight, which is preferably arranged eccentrically in the valve element, so that the weight exerts a torque on the valve element when the valve element is deflected from its initial position.Since centrifugal pump units, such as those used as heating circulation pump units, typically have a defined installation position in which the drive motor shaft runs horizontally, a defined starting position can also be ensured, in which the weight is located in one of at least two possible positions. When the valve element is rotated to a different switching position, the weight is lifted as long as the flow exerts a sufficient force on the valve element. If this force ceases, gravity moves the valve element back to its starting position.

[0024] The invention is described below by way of example with reference to the accompanying figures. These show: Fig. 1 a first perspective exploded view of a centrifugal pump assembly according to a first embodiment of the invention, Fig. 2 a perspective exploded view of the centrifugal pump assembly according to Fig. 1 From another perspective, Fig. 3 shows the circuit diagram of a heating system with a centrifugal pump unit according to Fig. 1 and 2 , Fig. 4 a top view of the opened pump housing of a centrifugal pump unit according to Fig. 1 and 2 with a valve element in a first switching position, Fig. 5 a view according to Fig. 4 with the valve element in a second switching position, Fig. 6 a front view of a centrifugal pump unit according to Fig. 1 and 2 , Fig. 7 a sectional view along line AA in Fig. 6 with a valve element in a released position, Fig. 8 a sectional view along line BB in Fig. 6 with the valve element in a second switching position, Fig. 9 a sectional view according to Fig. 8 with the valve element in a first switching position, Fig. 10 a sectional view along line AA in Fig. 6 with the valve element in a first switching position, Fig. 11 a sectional view according to Fig. 10 with the valve element in a second switching position, Fig. 12 a perspective exploded view of a centrifugal pump unit according to a second embodiment of the invention, Fig. 13 a view into the opened pump housing of a centrifugal pump unit according to Fig. 12 , Fig. 14 a sectional view of the centrifugal pump unit according to Fig. 12 Fig. 15 shows a perspective exploded view of a centrifugal pump assembly according to a third embodiment of the invention, and Fig. 16 shows a view into the opened pump housing of the centrifugal pump assembly according to Fig. 15 with a valve element in a first switching position, and Fig. 17 a view according to Fig. 16 with the valve element in a second switching position.

[0025] The centrifugal pump units described below are intended as heating circulation pump units, particularly for use in a heating system, such as a compact heating system, which serves both to heat a building and to heat domestic hot water. The centrifugal pump unit according to the first embodiment of the invention has an electric drive motor 2, which is arranged in a motor housing 4. The motor housing 4 is connected to a pump housing 6. An electronics housing 8 is arranged at the axial end of the motor housing 4 facing away from the pump housing 6. This electronic housing contains the electrical and / or electronic components for controlling and / or regulating the drive motor 2. The electric drive motor 2 is a wet-running electric drive motor. That is, the stator chamber, in which the stator 10 is arranged, is separated from a rotor chamber, in which the rotor 12 is arranged, by a containment shell.A canned tube 14 is separated. The rotor 12 thus rotates in the fluid to be pumped. The rotor 12 drives an impeller 18 via a rotor shaft 16 in a known manner. The impeller is arranged in the pump housing 6.

[0026] The pump housing 6 has a suction port 20 and two pressure ports 22 and 24. The suction port 20 opens at the bottom of the pump housing 6. A suction nozzle or inlet nozzle 26 is located there, which engages in the interior of a suction opening 28 of the impeller 18.

[0027] Surrounding the impeller 18, a cup-shaped valve element 30 is arranged inside the pump housing 6. The valve element 30 has a circular outer contour and extends concentrically to the axis of rotation X of the drive motor 2 and the impeller 18. The valve element 30 has an annular wall 32 on its outer circumference, which has a frustoconical outer contour and an outer contour that essentially corresponds to the inner contour of the pump housing 6 in the circumferential region of the axis of rotation X. At the axial end of the annular wall 32 with the larger diameter, the valve element 30 is fully open. At the opposite axial end, which has a smaller diameter, the valve element 30 has a wall 34 that forms a base of the valve element 30. The wall 34 extends transversely to the annular wall 32 and perpendicular to the axis of rotation X.The wall 34 forms an annular wall that extends radially inwards from the annular wall 32 and surrounds a central opening 36. The inlet nozzle 26 extends through the opening 36. This means that the valve element 30 is placed onto the inlet nozzle 26 with its opening 36 and secured there by an annular locking element 38. The locking element 38 engages the opening 36 from the inside and is fixed to the inlet nozzle 26, for example, by clamping. The inlet nozzle 26 and the locking element 38 are designed such that the valve element 30 is guided radially, but allows a certain degree of movement axially parallel to the longitudinal axis X.

[0028] Furthermore, a spring in the form of a wave-shaped spring ring 42 is arranged between a radially projecting shoulder 40 of the inlet nozzle 26 and the wall 34 of the valve element 30. The spring acts axially in the direction of the longitudinal axis X and pushes the valve element 30 away from the shoulder 40 in the direction of the drive motor 2. In this position, as shown in Fig. 7 As shown, the annular wall 32 and the wall 34 are spaced away from the inner surface of the pump housing 6, so that the valve element 30 can rotate essentially freely around the inlet port 26, i.e., around the longitudinal axis X inside the pump housing. In this state, a rotating flow generated by the impeller 18 inside the valve element 30 in the circumferential region can cause the valve element 30 to rotate due to friction between the flow and the wall surfaces of the valve element 30 (inner surface of the annular wall 32 and wall 34). The rotational movement is limited by a stop pin 44, which engages in an arcuate groove 46 in the base of the pump housing 6. The groove 46 extends over an angle of 90° around the longitudinal axis X. The groove 46 and the stop pin 44 ensure that the valve element 30 can rotate through an angle of 90° around the longitudinal axis X between two switching positions.

[0029] The switching opening 48 is formed in the circumferential annular wall 32. This opening is designed as a hole whose outer circumference is completely enclosed by parts of the annular wall 32. In a first switching position, the switching opening 48 can be brought into contact with an outlet opening 50, which is connected to the pressure port 22, so that a flow connection is established from the interior of the valve element 30 through the switching opening 48, the outlet opening 50, and to the pressure port 22. In the second switching position of the valve element 30, rotated by 90°, the switching opening 48 is brought into contact with an outlet opening 52, which is connected to the pressure port 24. That is, the pressure port 24 opens into the interior of the pump housing 6 at the outlet opening 52.In this switching position, a flow connection is thus established from the interior of the valve element 30 through the switching opening 48, the outlet opening 52 to the pressure port 24. This creates a switching valve, which, for example, enables a switching function as described in... Fig. 3 It can be implemented as described.

[0030] Fig. 3 Figure 1 schematically shows the circuit diagram of a heating system. This heating system has a primary heat exchanger 54, for example, a gas boiler. On the outlet side, i.e., downstream of the primary heat exchanger 54, a circulation pump unit 56 is arranged, which can be a centrifugal pump unit as described above and below. On the outlet side, i.e., on the pressure side of the circulation pump unit 56, a valve assembly 58 is integrated, which can be formed by the valve element 30 described above. The flow path between a heating circuit 60 for temperature control of a building and a secondary heat exchanger 62 for heating domestic hot water can be switched via the valve assembly 58 in order to supply either the heating circuit 60 or the secondary heat exchanger 62 with heat transfer fluid heated by the primary heat exchanger 54.

[0031] The switching or movement of the valve element 30 is achieved by a control electronics unit 64 located in the electronics housing 8, which controls the drive motor 2. The control electronics unit 64 can, in particular, include a speed controller or frequency converter. The switching process utilizes the fact that, during rapid start-up of the drive motor 2 and the impeller 18, pressure builds up more quickly in the circumferential region of the impeller than an annular flow suitable for rotating the valve element 30. For example, when the valve element is in the Fig. 4 In the first switching position shown, in which the flow path through the pressure port 22 is open and the valve element 30 is to remain in this switching position when the drive motor starts, the drive motor 30 is rapidly accelerated so that pressure quickly builds up inside the valve element 30 and it opens from the position shown in the first switching position. Fig. 7 The valve element 30 is pressed from the released position shown into a closed position, in which the outer surface of the ring wall 32 and the wall 34 come into frictional contact with the inner surfaces of the pump housing 6, thus securing the valve element 30 against rotation. The outer surface of the valve element 30 therefore forms a releasable coupling with the inner surface of the pump housing 6.

[0032] To remove the valve element 30 from the in Fig. 4 shown first switch position in the Fig. 5 When the second switching position shown is turned, the impeller 18 is driven by the drive motor 2 in direction A at such a low speed that no pressure can build up inside the valve element 30 that could overcome the spring force generated by the spring ring 42. The valve element 30 thus remains in the position shown. Fig. 7 shown in the relaxed position. After a certain time, however, a ring flow in the direction of rotation A also builds up inside the valve element 30, which rotates the valve element 30 via frictional forces and thus into the in Fig. 5 The second switching position shown is moved. If the speed of the drive motor 2 is subsequently increased further, the valve element 30 returns to its closed position in frictional contact with the inner surface of the pump housing 6 in this switching position. However, it is also possible to switch off the drive motor again in this switching position and then start it up directly in the opposite direction of rotation B at such a high speed that a pressure of such high amplitude is immediately generated that the valve element 30 moves in the axial direction X into the Fig. 8 The valve element 30 is moved to the shown position and thus cannot be rotated by the flow in the direction of rotation B. To rotate the valve element 30 back to the first switching position, the drive motor must be driven in the direction of rotation B at such a speed that a flow can build up to move the valve element 30, but not a pressure high enough to overcome the spring force of the spring ring 42.

[0033] Fig. 10 Figure 1 shows the first switching position with the valve element 30 in the closed position. The switching opening 48 is opposite the outlet opening 50. Fig. 11 Figure 1 shows the second switching position, in which part of the ring wall 32 is opposite the outlet opening 50, so that it is closed. Conversely, in the second switching position, as shown in Figure 2, the ring wall 32 is opposite the outlet opening 50, so that the outlet opening 50 is closed. Fig. 8 The switching opening 48 is shown opposite the outlet opening 52, while in the first switching position, as in Fig. 9 shown, a part of the ring wall 32 is opposite the outlet opening 52 and thus closes it off. In Fig. 8 bis 11 The valve element 30 is in its adjacent position, so that it rests against the inner wall of the pump housing 6 in the circumferential area of ​​the outlet openings 50, 52 and can tightly close these, provided that the annular wall 32 covers the outlet opening 50, 52.

[0034] The Fig. 12 bis 14 Figure 1 shows a second embodiment of a centrifugal pump assembly according to the invention, in which the valve element differs from the valve element 30 described above only in the manner of its mounting. Only the differences from the first embodiment are described below. For all other aspects, reference is made to the preceding description. In this second embodiment, the valve element 30' is rotatably mounted on a bearing pin or bolt 66. The bearing bolt 66 extends axially along the longitudinal axis X from the bottom into the interior of the pump housing 6. The valve element 30 has an integrally formed suction port 68 on its wall 34, which engages with the suction opening 28 of the impeller 18 instead of the inlet port 46.Inside the suction port 68 is a suction opening in which a bearing sleeve 70 is held by means of connecting webs, the bearing sleeve 70 being formed integrally with the remaining part of the valve element 30'. The bearing sleeve 70 is mounted on the bearing pin 66, i.e., it rotates on the bearing pin 66. A spring 72 in the form of a compression spring is also arranged around the bearing pin 66. The spring 72 performs the function of the spring ring 42 according to the first embodiment and generates a compressive force between the bottom of the pump housing 6 and the valve element 30', so that the latter is in the position shown in the original text. Fig. 14 In the loosened position shown, the bearing sleeve 70 is pushed away from the inner wall of the pump housing 6 and can rotate freely. In this position, the bearing sleeve 70, with its closed axial end 74 facing away from the pump housing 6, is supported against the axial end of the rotor shaft 16. The operation of the valve element 30' corresponds to the preceding description. Apart from the different bearing arrangement, there are no differences.

[0035] The third embodiment according to Fig. 15 bis 17 This embodiment essentially corresponds to the second embodiment, so only the differences will be described below. For all other aspects, please refer to the preceding description.

[0036] The valve element 30" has an internal spiral flow guide 46, which forms a spiral channel towards the switching orifice 48. The flow guide 46 is designed as a spiral projection that narrows radially towards the switching orifice 48, thus increasing the free space between the flow guide 76 and the impeller 18 and creating a spirally widening flow channel towards the outlet orifice 48. During operation, the flow proceeds in the direction of rotation A. Fig. 16 und 17 Since the flow guide 76 rotates together with the valve element 30" between the switching positions, optimal flow guidance is always ensured towards each of the pressure ports 22 and 24 during operation. It is understood that such a flow guide 76 could also be used in the first two embodiments.

[0037] Furthermore, the valve element 30" has a weight 78, which is arranged in a receptacle in the base or wall 34 of the valve element 30". The weight 78 is diametrically opposite the switching opening 48, so that it is in the Fig. 16 The first switching position shown is at the bottom. The weight 78 serves as a return element, so that the drive motor 2 only needs to be driven in one direction of rotation A. To return the valve element 30", it is not necessary to generate an annular flow in the opposite direction inside the valve element 30". Rather, the return occurs by gravity when the weight 78 moves downwards. When the pump unit is in the Fig. 16 To activate the first switching position shown, the drive motor 2 is driven or accelerated by the control electronics 64 in such a way that a pressure immediately builds up that is high enough to overcome the spring force generated by the spring 72 by a pressure force inside the valve element 30". This means that the valve element 30" is pressed by the generated fluid pressure against the spring force of the spring 42 in contact with the inner wall of the pump housing 6, so that it is frictionally locked in place and remains in the first switching position shown. To move the valve element 30" into the position shown in Fig. 17 To move the second switching position shown, the drive motor 2 is started up correspondingly more slowly by the control electronics 64, so that an annular flow can initially build up in the direction of rotation A, which moves the valve element 30" in the Fig. 14 rotates in the shown resolved position and thus into the Fig. 17 The second switching position shown rotates. In this position, the drive motor can be accelerated further, so that a fluid pressure builds up inside the valve element 30" that the valve element 30' is pressed into the closed position. When the drive motor is switched off, both the annular flow and the built-up pressure cease, and the valve element 30" returns to the released position due to the action of the spring 72. In this position, it can rotate freely again, and the weight 78 generates a torque so that the valve element 30" automatically returns to the closed position in the opposite direction of rotation A. Fig. 16 The first switch position shown reverses.

[0038] It is understandable that such a return element could also be used in the first two embodiments. Instead of a return element acting by gravity, for example a spring or a magnetically acting return element could also be used.

[0039] In addition to axial movement of the entire valve element 30, 30', 30" between the released and closed positions, a movable section of the valve element 30, 30', 30" could also be moved between a released and closed position. For example, the ring wall 32 could be elastically designed to be deformed by an internal fluid pressure and brought into contact with an inner wall of the pump housing 6. Bezugszeichenliste

[0040] 2 Drive motor 4 Motor housing 6 Pump housing 8 Electronics housing 10 Stator 12 Rotor 14 Slotted tube 16 Rotor shaft 18 Impeller 20 Suction port 22, 24 Pressure ports 26 Suction nozzle, Inlet nozzle 28 Suction mouth 30, 30', 30'' Valve element 32 Ring wall 34 Wall 36 Opening 38 Locking element 40 Shoulder 42 Spring ring 44 Stop pin 46 Groove 48 Switching opening 50, 52 Outlet opening 54 Primary heat exchanger 56 Circulating pump unit 58 Valve assembly 60 Heating circuit 62 Secondary heat exchanger 64 Control electronics 66 Bearing bolt 68 Suction nozzle 70 Bearing sleeve 72 Spring 74 Axial end 76 Flow guide 78 Weight XL Longitudinal axis A, B Directions of rotation

Claims

1. A centrifugal pump assembly having an electric drive motor (2), at least one impeller (18) driven by the same and a pump housing (6) surrounding the impeller (18), which pump housing has at least one suction connector (20) and at least two pressure connectors (22, 24), wherein a rotatable valve element (30, 30', 30") is arranged in the pump housing (6), which valve element can be moved between at least two switching positions, in which the flow paths through the at least two pressure connectors (22, 24) are open to different widths, wherein the valve element (30, 30', 30") has an annular wall (32) surrounding the impeller (18), in which annular wall at least one switching opening (48) is formed, wherein the valve element (30, 30', 30") is mounted in the interior of the pump housing (6) in a rotatable manner about an axis of rotation (X) that is central in relation to the annular wall (32), and wherein a flow generated by the impeller (18) can act directly on the annular wall (32) in order to rotate the valve element (30, 30', 30") about the axis of rotation (X) depending on the flow, characterized in that the entire valve element (30, 30', 30") can be moved in a direction transverse to its direction of rotation (A, B) and parallel to its axis of rotation (X) between a bearing position, in which it bears in a frictional manner against a bearing surface in the pump housing (6), and a released position, in which the valve element (30, 30', 30") can be moved relative to the bearing surface, wherein a force generating means is present, which loads the valve element (30, 30', 30") with force out of the bearing position in the direction of the released position, and the valve element (30, 30', 30") is configured such that the valve element (30, 30', 30") is held in its switching position, which it has assumed, by the frictional bearing in the bearing position.

2. The centrifugal pump assembly according to Claim 1, characterized in that at least one, preferably two outlet openings (50, 52) that are connected to the pressure connectors (22, 24) are located in a wall of the pump housing (6) facing the annular wall (32), with which outlet opening(s) the at least one switching opening (48) can be brought to overlap at least partially, depending on the switching position of the valve element (30, 30', 30").

3. The centrifugal pump assembly according to Claim 1 or 2, characterized in that, in the interior of the annular wall (32), valve element (30, 30', 30") has a wall (34) extending transversely to the axis of rotation, which wall preferably surrounds a suction nozzle (28) of the impeller (18).

4. The centrifugal pump assembly according to any one of the preceding claims, characterized in that the annular wall (32) has a circular outer contour and preferably a cylindrical or conical outer contour.

5. The centrifugal pump assembly according to any one of the preceding claims, characterized in that the valve element (30; 30', 30") is mounted in a rotatable manner on a stationary component (66; 26) in the interior of the pump housing (6), wherein the valve element (30', 30") preferably has a bearing sleeve (70) at its centre, which bearing sleeve slides in a rotatable manner on a stationary bearing bolt (66) in the pump housing (6) and / or the valve element (30) is mounted in a rotatable manner on an inlet nozzle (26) which is arranged in the pump housing (6) and is in engagement with a suction nozzle (28) of the impeller (18).

6. The centrifugal pump assembly according to any one of the preceding claims, characterized in that the at least one switching opening (48) is completely surrounded at its edge by at least one section of the annular wall (32).

7. The centrifugal pump assembly according to any one of the preceding claims, characterized in that the annular wall (32) has a direction of extent transverse to its circumference at an angle of less than 90° and preferably less than 45° to the axis of rotation (X).

8. The centrifugal pump assembly according to any one of the preceding claims, characterized in that the valve element (30, 30', 30") and the pump housing (6) are configured in such a manner that in the bearing position, at least one section of the valve element (30, 30', 30") bears against an inner wall of the pump housing (6).

9. The centrifugal pump assembly according to any one of the preceding claims, characterized in that the valve element (30, 30', 30") is configured in such a manner that a pressure prevailing in the circumferential region of the impeller (18) acts on the valve element (30, 30', 30") such that the entire valve element (30, 30', 30") is moved into the bearing position.

10. The centrifugal pump assembly according to any one of the preceding claims, <b>characterized in that the at least one force generating means is a spring (42; 72).

11. The centrifugal pump assembly according to any one of the preceding claims, characterized in that a flow guide element (76), which leads to the at least one switching opening (48) and is preferably formed in a spiral-shaped manner, is located on the inner circumference of the annular wall (32).

12. The centrifugal pump assembly according to any one of the preceding claims, characterized by a restoring element (78) acting on the valve element (30") in its direction of rotation (B), which restoring element is formed in such a manner that, in the event of stoppage of the impeller, it moves the valve element (30") into a predetermined starting position, wherein the restoring element is preferably a weight (78) which is arranged on the valve element (30").

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