EP3662204A1

EP3662204A1 - Circulation pump assembly

Info

Publication number: EP3662204A1
Application number: EP18745974.8A
Authority: EP
Inventors: Thomas Blad; Christian BLAD
Original assignee: Grundfos Holdings AS
Current assignee: Grundfos Holdings AS
Priority date: 2017-08-03
Filing date: 2018-08-02
Publication date: 2020-06-10
Also published as: US11359822B2; US20200340684A1; WO2019025525A1; EP3438555A1; CN110998191A; CN110998191B

Abstract

The invention relates to a circulation pump assembly comprising a first inlet (84), an outlet (80), an electric drive motor (30) and at least one impeller (68; 100) driven by the drive motor (30) and which has at least one first flow path (26; 48) positioned in a connection between the first inlet (84) and the outlet (80) for increasing the pressure of a fluid, wherein the circulation pump assembly has a second inlet (86) and the at least one impeller (68; 100) has at least one second flow path (28; 50) for increasing the pressure of a fluid, which is positioned in a connection of the second inlet (86) to the outlet (80), as well as a heating system having a circulation pump assembly of this type.

Description

description

[Ol] The invention relates to a circulation pump unit and a heating system with such a circulation pump unit.

In heating system circulating pumps are used to circulate a liquid heat carrier or a heating medium, in particular water through the heating system. When heating circuits are used in heating systems, which require different flow temperatures, it is common to provide mixers, which can reduce the flow temperature for certain heating circuits, such as heating circuits of a floor heating. Such mixers are often used in combination with Kompaktheizkesseln, which in addition to a heat source, such as a boiler with primary heat exchanger, also already have a circulating pump unit for circulating the heat carrier through the heating system. This circulating pump unit provides a residual head which is adapted to be sufficient for a conventional heating circuit with radiators with thermostatic valves. For a further heating circuit with reduced flow temperature then a second circulating pump unit is usually used, which is arranged downstream of a mixing valve, via which the heated heat carrier from the boiler is injected into the heating circuit with lower flow temperature. It is necessary in the mixing valve or an upstream valve to reduce the provided by the circulating pump unit in the boiler form to the pressure level at the input side of the circulating pump unit in the second heating circuit. Ie. the of the residual pumping height provided to the circulating pump unit in the boiler is destroyed and an energy loss occurs.

[03] In view of this problem, it is an object of the invention to improve a heating system in such a way that the energy losses in a mixer can be minimized. This object is achieved by a circulating pump unit having the features specified in claim 1 and by a heating system with the features specified in claim 15. Preferred embodiments will become apparent from the subclaims, the following description and the accompanying figures.

[04] The circulating pump unit according to the invention is provided, in particular, as a heating circulation pump unit for use in a heating system, heating system in the sense of this invention also meaning an air conditioning system which does not serve to heat but to cool. Quite generally, the circulating pump unit according to the invention can be used for circulating a liquid heat carrier or heating medium for tempering a building or a plant.

[05] The circulation pump unit according to the invention has a first input, ie a first suction input and an output. The output is a pressure outlet through which liquid exits the circulating pump unit. Furthermore, the circulating pump unit has an electric drive motor, which rotatably drives at least one impeller provided in the circulating pump unit. Ie. The circulating pump unit is a centrifugal pump unit. The electric drive motor is particularly preferably designed as a wet-running electric drive motor, ie as a motor with a split tube or containment shell between the rotor and the stator. The at least one impeller is in the circulating pump unit in a connection or flow connection between the first input and the output. The impeller has at least one flow path in this flow connection and serves to increase the pressure of a liquid. So the impeller can be a liquid, eg. As a liquid heating medium, promote from the first input to the output and increase the pressure of the liquid between the input and output. The at least one flow path through the impeller can be formed for example by conventional channels between impeller blades. [06] According to the invention, the circulating pump unit has a second input, wherein in the circulating pump unit a second flow connection is formed from this second input to the outlet. The second input thus forms a second suction inlet or suction connection, wherein during operation of the circulation pump unit, a different pressure level can prevail at the second input than at the first input. The at least one impeller further comprises at least a second flow path with pressure increase of a liquid such as a liquid heating medium, said second flow path is in the described flow connection between the second input and the output. This means that the circulation pump assembly according to the invention in the at least one impeller has two separate flow paths, via which an increase in pressure can be achieved. This configuration allows liquids such. B. two flows of a liquid heating medium from the two inputs, which have at the two inputs a different input or form, to increase the same final pressure at the output. Ie. the at least one impeller with the two flow paths is designed so that it generates two different pressure differences during its rotation. [07] This embodiment according to the invention makes it possible to use the circulation pump unit in a heating circuit with a mixer and to supply the second input of the circulation pump unit with liquid having a pre-pressure, ie, a residual delivery height. This pre-pressure can be provided for example by a circulation pump in a boiler or a compact heating system. The mixing point of the mixer is then located in the described Umwälzpumpenaggregat in this arrangement and it is no longer necessary to reduce the form or the residual head on the input side of the mixer to the same suction pressure on the suction side of Umwälzpumpenaggregates in the over the mixer to be supplied to the heating circuit to reach. On the contrary, the circulatory pump unit according to the invention can be supplied with fluids at two different pressure levels. The liquid to be circulated in the heating circuit to be supplied is supplied to the first inlet, while the liquid to be admixed is admixed with a higher pressure level via the second inlet. The circulating pump unit according to the invention thus makes it possible to reduce the energy losses during operation of a mixer. As underfloor heating usually has the largest share in modern heating systems, energy savings in the circulation pump unit area of up to 30% can be achieved in this way

[08] The two separate flow paths in the at least one impeller are preferably formed to have a fixed, non-variable aspect ratio to each other. Ie. Preferably, it is not provided to change a mixing ratio, to change a cross-sectional ratio of the two flow paths. This simplifies the structure, since no corresponding valve devices and no displacement of the impeller are required. Particularly preferred is a change in the mixing ratio Rather, it is achieved by changing the speed of the at least one impeller, as will be described below.

[09] Preferably, the at least one first flow path and the at least one second flow path are arranged in a common impeller. Ie. upon rotation of the impeller with the two flow paths, a pressure increase of the liquid flowing through these flow paths takes place via both flow paths. Alternatively, it is possible to use two non-rotatably arranged wheels, which rotate together. These may be integrally formed with each other or rotatably connected to each other in any other suitable manner. For example, an impeller with two blade rings can also be used, wherein a first blade ring defines the first flow paths and a second blade ring defines the second flow paths. Such an impeller may be formed so that the inlets or inlets for the two flow paths are located on the same axial side, viewed in the direction of the axis of rotation, or else against each other in the axial direction opposite sides. Even when using two wheels, these could be arranged so that the inlet sides or suction openings are directed opposite. Such an arrangement has the advantage that the axial forces occurring at least partially cancel.

[10] According to another preferred embodiment of the invention, it is possible that the at least one second flow path is formed by a portion of the at least one first flow path. In this case, the first flow path then has a first section, in which only the liquid flowing through the first flow path experiences an increase in pressure. The second inlet opens into a second section of the first flow path, in which then both the liquid which is supplied from the second input and that from the first section of the first flow path leaking fluid experienced an increase in pressure. Ie. In the second flow path, both the fluid flow from the first inlet and the fluid flow from the second inlet experience an increase in pressure. When liquid at a pre-pressure is supplied at the second inlet, this has the advantage that in the first section of the first flow path the liquid supplied via the first inlet with a lower pre-pressure experiences a first pressure increase, so that at the point at which the Flow from the second input opens into the first flow path, the liquids from the first and the second input have a substantially equal pressure level.

[1 1] Further preferably, the at least one impeller has a suction mouth as a first inlet opening, from which the at least one first flow path extends to an outlet side of the impeller. The suction mouth as the first inlet opening communicates with the first inlet of the circulating pump unit and the outlet side of the impeller communicates with the outlet of the circulating pump unit. The impeller preferably has at least one second inlet opening, which is located in the direction of the flow through the impeller between said suction mouth and the outlet side. This at least one second inlet opening is connected to the second input of the circulating pump unit. Thus, a liquid flow with a higher pressure level can be introduced into the impeller via the second inlet opening at a position at which the liquid in the impeller, which is supplied through the suction mouth, has already experienced a certain pressure increase. When using this Umwälzpumpenaggregates in a mixer or as a mixer thus the mixing point of the two flows is in the impeller. Thus, two liquid flows with different pre-pressure can be mixed at a mixing point with essentially the same pressure level, without the higher pressure in one of the two guided Flüssigkeifssströmströmungen would first have to be reduced. As a result, the energy loss can be minimized.

[12] The second inlet opening preferably opens into a first flow path, wherein the section of the at least one first flow path between the at least one second inlet opening and the outlet side simultaneously forms the at least one second flow path. Ie. the second flow path forms a common flow path through which both the fluid flow from the first inlet and the fluid flow are directed out of the second inlet, wherein the fluid flow from the first input of the circulating pump assembly in a first portion of the first flow path upstream of the at least one second inlet has already experienced an increase in pressure regardless of the flow from the second input. [13] Particularly preferably, the impeller has a plurality of second inlet openings. As a result, the flow cross-section can be increased and thus the hydraulic resistance in the second flow path can be minimized.

Preferably, a plurality of first flow paths are formed between rotor blades of the at least one impeller, and at least one second inlet opening opens into each of the first flow paths between the impeller blades. The sections of the first flow paths between the suction mouth and the second inlet openings then form the described first flow paths, through which only the liquid supplied through the first inlet is conveyed. The second sections of the first flow paths downstream of the second inlet openings form with these a second flow path through which the liquid which is supplied through the second inlet is also conveyed. Because of that second Inlet openings are arranged in each of the first flow paths, a maximum flow cross-section for the second flow paths in the impeller is provided.

[15] More preferably, the at least one second inlet opening is formed in a cover disc surrounding the suction mouth. Ie. the impeller is designed as a closed impeller, which has a cover plate which closes the flow paths between the impeller blades in the circumference of the centrally arranged suction mouth. The suction mouth forms the first inlet opening for the first flow paths. The second inlet openings are formed as holes or gaps in the cover disk, which open into these flow paths between the impeller blades, so that the flow paths radially outside of the second inlet openings form the second flow paths as described above. [16] The suction mouth of the at least one impeller is preferably engaged with a fixed ring element, in the interior of which a flow connection opens from the first inlet. Thus, a flow connection is made from the first inlet into the interior of the impeller and into the first flow paths of the impeller. The ring member is further preferably in substantially sealing engagement with the suction mouth, d. H. a suction mouth is formed between the suction mouth and the ring element in order to reduce or avoid leaks in this area.

[17] Further preferably, an annular space is formed on the outer circumference of the described annular element, into which a flow connection opens from the second inlet, wherein the at least one second inlet opening of the impeller faces this annular space. In this embodiment, the ring element thus forms a partition wall between the first and the second flow connection, wherein the flow mungsverbindung from the first input on the inside of the annular wall and the flow connection from the second input on the outside of the ring member to the impeller extends.

[18] According to a further preferred embodiment of the invention, the impeller is in sealing engagement with a part of a surrounding pump housing radially outside the at least one second inlet opening. This sealing engagement forms a seal between suction and pressure side of the impeller, so that the outlet side of the impeller is sealed against the flow connection to the at least one second inlet opening.

[19] According to a particular embodiment of the invention may be arranged at least in the flow connection between the second input and the at least one impeller, a valve for adjusting the flow through this flow connection. This valve can form a mixing valve, via which the amount of liquid supplied from the second input can be regulated, for example, to be able to regulate the temperature of the mixed flow at the outlet of Umwälzpumpenaggregates. For this purpose, the valve may preferably have an electric drive for changing the valve position, the electric drive preferably being a stepper motor. The valve can then be actuated by a control device which adjusts the valve position, for example, as a function of temperature as a function of the temperature on the outlet side of the circulating pump unit, ie as a function of the temperature of the mixed flow. This creates a mixer with temperature control. However, it can also be arranged in one or both flow connections manually operated flow control valves to z. B. to be able to make a default of the flow rates. [20] Particularly preferably, the circulation pump unit has a control device which is designed to set the speed of the drive motor. By way of example, the control device can be designed such that it performs a pressure and / or flow control in order to maintain the pressure and / or flow in the range of predetermined setpoint values. Alternatively, a temperature-dependent speed control is possible, in which the rotational speed is set in dependence on a temperature signal so that a temperature value is maintained in the range of predetermined target values. Thus, for example, by speed control or speed change of the circulating pump unit, the temperature on the output side of the circulating pump unit, that is regulated at the output or in the liquid flow flowing through the outlet.

[21] In addition to the Umwälzpumpenag- described above, the subject of the invention is also a heating system with such a circulation pump unit, wherein the Umwälzpumpenaggregat described above forms a first Umwälzpumpenaggregat in the heating system. The heating system according to the invention also has a second circulating pump unit, which is located upstream of the second input of the first pump unit. Thus, the second circulating pump unit leads to the inlet of the first pump unit, a liquid flow with a pre-pressure, which is generated by the second circulating pump unit to. The second circulation pump unit is preferably a centrifugal pump unit, which is adjustable in its speed via a control device. This centrifugal pump assembly also preferably has an electric drive motor, which can be further preferably designed as a wet-running drive motor. The admission pressure or flow can be adjusted or regulated via the speed adjustment. The speed control of the second circulating pump unit is preferably carried out so that the flow and / or the pressure in the range of desired predetermined setpoint values is maintained or follows a predetermined characteristic. Both the first circulating pump unit and the second circulating pump unit can be designed such that they have a frequency converter for speed control.

[22] Further preferably, a control device is provided in the heating system according to the invention, which is designed such that it controls the first circulating pump unit and / or the second circulating pump unit and / or a valve located in the flow path from the second input to the at least one impeller to set a mixing ratio of the liquid flows from the first input and the second input in the first circulation pump unit. The speed control is preferably temperature-dependent. Ie. the control device is preferably connected to at least one temperature sensor and controls the rotational speeds of the circulating pump assembly or of the circulating pump assemblies so that the temperature detected by the temperature sensor is maintained at a desired desired value or approximated to a desired setpoint. The temperature sensor is preferably arranged on the outlet side of the first circulating pump assembly, so that it detects the temperature of the mixed liquid flow flowing through the outlet of the first circulating pump assembly. If the control device varies the rotational speed of the second circulating pump assembly, the amount of liquid supplied to the second input can thus be changed. The same can be accomplished by adjusting a valve upstream of the second inlet of the first recirculation pump assembly. By changing the speed of the first circulation pump unit, it is likewise possible to change the mixing ratio if the flow and / or pressure ratio of the flows through the first and the second flow path changes as a function of rotational speed. This can be done through appropriate geometric configuration of the first flow path and the second flow path can be achieved, in particular when the first and second flow paths end, for example, on different outer diameters of the impeller. Thus, different pressure increases are achieved at the same speed. Furthermore, changes in the pressure ratio can be achieved in that the liquid is supplied to the second input with a, preferably constant, admission pressure. When the flow connection from the second input opens into a first flow path of the impeller, as described above, the pressure at the orifice point in the interior of the impeller is changed with speed change, so that by changing the pressure conditions in the two flow paths, the mixing ratio in the interior of the impeller is changed.

[23] The invention will now be described by way of example with reference to the attached figures. In these shows:

1 is a hydraulic circuit diagram of a heating system according to the prior art,

2 shows a hydraulic circuit diagram of a heating system according to a first embodiment of the invention, FIG. 3 shows a hydraulic circuit diagram of a heating system according to a second embodiment of the invention,

4 shows a hydraulic circuit diagram of a heating system according to a third embodiment of the invention, 5 shows a hydraulic circuit diagram of a heating system according to the exemplary embodiment according to FIG. 3 with a double impeller, FIG. 6 shows an exploded view of a circulating pump assembly with a mixing device corresponding to the heating system according to FIGS. 2, 3 and 5,

6 is a sectional view of the circulating pump assembly according to FIG. 6 along its longitudinal axis x, FIG. 8 is a plan view of the rear side of the circulating pump assembly according to FIGS. 6 and 7,

9 is a partially sectional view of the rear of Umwälzpumpenaggregates of FIG. 6 to 8, Fig. 10 is an exploded view of a circulating pump unit with a mixing device according to the embodiment of FIG. 4,

10 is a sectional view of the circulating pump assembly according to FIG. 10 along its longitudinal axis X, FIG. 12 is a plan view of the rear side of the circulating pump assembly according to FIGS. 9 and 10, FIG. 13 is the pressure curve over the rotational speed for the embodiment of a heating system according to FIG. 2, 14 shows the pressure curve over the rotational speed for an embodiment of a Heizungssysfems of FIG. 3 and

FIG. 1 shows schematically a conventional heating circuit for a floor heating 2, ie a heating circuit according to the state of the art. FIG. As a heat source dienf a boiler 4, for example, a gas boiler mif an integrated circulating pump 6. Such combinations are known, for example, as a compact heating systems on the market. For the underfloor heating circuit 2, a further circulating pump unit 8 with an impeller 10 and an electric drive motor 12 is provided. Since the boiler 4 provides an excessively high flow temperature for the underfloor heating 2, here a Mischeinrichfung is provided, which has a mixing point 14 which is located on the suction side of the impeller 10. At the mixing point 14, a return line 16 of the floor heating circuit 2 opens. Mündungspunkf 14 a Vorlaufderifung 18, via which the heated by the boiler 4 water or heating medium is supplied and injected at the mixing point 14 by the generated by the Umwälzpumpenaggregaf 6 FEN pressure. To regulate the mixing ratio, two flow regulating valves R _ho t and Rcoid are provided in this embodiment. The Reguliervenfil R _ho t is arranged in the lead grinding 18 and the Reguliervenfil R _CO id in the return run 16. The Venfile can be controlled for example by a control device via an electric drive see. Preferably, the Reguliervenfile Rhot and Rcoid be coupled so that to change the flow always open one of the valves and at the same time the other valve is closed by the same degree. Instead of two Durchflußreguliervenfile R can also be a 3-way Venfil be used, which has a Ventilelemenf, by its movement at the same time Return line 1 6 closes and the supply line 18 opens or vice versa. The circulating pump unit 6 can also supply a further heating circuit, not shown here, which is operated directly with the flow temperature generated by the boiler. Both the circulating pump unit 6 and the circulating pump unit 8 may have a conventional pressure or flow control. In the known system, it is disadvantageous that the flow regulating valves R are required for adjusting the mixing ratio and must be provided with a corresponding drive, for example a motor-driven or thermo-actuated drive. The flow regulating valves R are controlled so that a desired flow temperature for the underfloor heating 2 is achieved downstream of the mixing point 14. A further disadvantage in this system is that the pressure generated by the circulating pump unit 6 has to be reduced via the flow regulating valve R _ho t in order to achieve the suction-side pressure of the impeller 10 at the mixing point 14. Thus, an energy loss occurs in the system, which can be avoided with the solution according to the invention described below.

[25] In the case of the three exemplary solutions according to the invention, which are shown schematically in FIGS. 2 to 4, the mixing ratio for achieving a desired flow temperature for underfloor heating 2 is achieved solely by a speed control of a circulating pump unit. This has two flow paths which hydraulically influence each other so that by speed change, the hydraulic resistance in at least one of the flow paths can be changed to change the mixing ratio, as will be described below.

[26] Fig. 2 shows a first embodiment of the invention. In this turn, a boiler 4 for heating a liquid heating medium, ie a liquid heat carrier such as water is provided. To the- sem boiler 4, a circulating pump unit 6 is further arranged, which could also be integrated into the boiler 4, as explained with reference to FIG. The circulating pump unit 6 conveys heated heat carrier in a flow line 18. Further, a Fußbo- is heating 2 or a Fußbodenheizkreis 2 is provided, which has a return, which is connected to one side to the input side of the boiler 4 and the other via a return line 16 to a Mixing point 20 leads, at which also the flow line 18 opens. The mixing or orifice point 20 is part of a mixing device 22 and further of a circulation pump assembly 24. The mixing device 22 and the circulation pump unit 24 may form an integrated unit, so that the mixing device 22 is part of the circulating pump unit 24 or the circulation pump unit 24 is part of the mixing device 22 , In particular, the mixing point 20, as will be described below, lie directly in the pump housing or in an impeller of the circulating pump unit 24.

[27] In the embodiment of FIG. 2, the circulating pump unit 24 is formed as a double pump with two impellers 26 and 28. The wheels 26 and 28 are driven by a common drive motor 30. The wheels 26 and 28 may be formed as separate wheels or as an integrated impeller with two blade assemblies or flow paths. The first impeller 26 forms a first flow path and is in a first flow connection in the mixing device from the return line 16 to the mixing point 20. The second impeller 28 forms a second flow path and is in a second flow connection between the flow line 18 and the mixing point 20. Der Mixing point 20 is thus on the pressure side of the two wheels 26 and 28, that is, according to the invention, the two heating medium streams are mixed together after the pressure increase. The drive motor 30 is controlled by a control device 34, which is used for speed control or speed control of the drive motor 30 and is designed so that it can change the rotational speed of the drive motor 30. For this purpose, the control device 34 has a speed controller, in particular using a frequency converter. The control device 34 may be integrated directly into the drive motor 30 or be arranged in an electronics housing directly on the drive motor and in particular on the motor housing. The control device 34 is furthermore connected to a temperature sensor 36 or communicates with a temperature sensor 36. The temperature sensor 36 is located downstream of the mixing point 20 on or in the feed line 38, which connects the mixing point 20 to the floor heating circuit 2. In this case, the temperature sensor 36 can be integrated into the mixing device 22 or the circulation pump unit 24. The connection of the temperature sensor 36 to the controller 34 may be provided in any suitable manner, for example, wired or wireless. A wireless connection can be realized for example via a radio link such as Bluetooth or W-LAN. [29] The temperature sensor 36 transmits a temperature value of the heating medium downstream of the mixing point 20 to the controller 34 so that it can perform temperature control. According to the invention, the drive motor 30 and thus the circulating pump unit 34 are not dependent on the pressure or flow, but are regulated depending on the temperature. Ie. the controller 34 adjusts the rotational speed of the drive motor 30 so that a desired temperature of the heating medium downstream of the mixing point 20 is achieved. The desired temperature is predetermined by a desired temperature value, which may be fixed, which may be manually adjustable, or which may also be predetermined outside temperature-dependent by a heating curve, which may be present in the control device 34 or an overflow temperature. ordered control is deposited. The control device 34 varies the rotational speed of the drive motor 30, as a result of which, as described below, the mixing ratio of the heating medium flows which are mixed at the mixing point 20 changes, so that the temperature changes downstream of the mixing point 20. This temperature is detected by the temperature sensor 36, so that the control device 34 can perform a temperature control by speed variation of the drive motor 30 to approximate the temperature value downstream of the mixing point 20 to the temperature setpoint value. The variation of the mixing ratio at the mixing point 20 via the speed change will be explained in detail with reference to FIG. In FIG. 13, the delivery height H, ie the pressure above the rotational speed n of the drive motor 30, is plotted. In the example given in FIG. 2, there are three differential pressure values ΔP _pre , AP _ho t and AP _CO id. The differential pressure AP _pre is generated by the circulating pump unit 6 and can not be influenced by the mixing device 22 in this case, so that it is shown in FIG. 13 as a constant, ie independent of the speed of the drive motor 30 form. The impeller 26 of Umwälzpumpenaggregates 24 generates for the return of the underfloor 2 a differential pressure AP _CO i _d and the impeller 28 generates for the flow from the supply line 18 a differential pressure AP _ho t- As can be seen in Fig. 13, the wheels 26 and 28 differently shaped, so that they have different pressure gradients, ie different speed-dependent pressure gradients. The pressure curve for the impeller 28 is less steep than the pressure curve of the impeller 26. This can be achieved, for example, that the impeller 26 has a larger outer diameter. For the heated heating medium, which is supplied through the supply line 18, moreover, add the differential pressures AP _pre and AP _ho t, so that the pressure curve AP _h ot is shifted by a constant value in the diagram upwards. This ensures that the pressure curves AP _ho t and intersect AP _C oi _d at a point 39. Above and below the point of intersection of these curves are mixing areas 40 for the mixed liquid. At a speed n below the intersection 39 of the two pressure curves, the output pressure of the impeller 28 is higher than that of the impeller 26, so that the output pressure of the impeller 28 acts in the flow path through the impeller 26 at the mixing point 20 as a back pressure and hydraulic resistance and in this Operating state, the flow through the first flow path through the impeller 26 is reduced and more heated Heizme- dium is mixed in order to achieve a higher temperature in the flow 38 to the underfloor 2. When the rotational speed is increased, above the point of intersection 39 of the two pressure curves, the output pressure of the impeller 26 is higher than that of the impeller 28, so that in the second flow path through the impeller 28 a hydraulic resistance in the form of a back pressure is generated at the mixing point 20 and the flow through the second flow path is reduced, whereby less heated heating medium is supplied at the mixing point 20 and the temperature on the output side of the mixing point 20 can be reduced. [31] FIG. 3 shows a further variant of a mixing device according to the invention or a heating system according to the invention, which differ from the heating system according to FIG. 2 in that no circulating pump unit 6 is provided in the supply line 18. Ie. the heated heating medium is supplied via the supply line 18 without form the Umwälzpumpenaggregat 24. This results in the pressure curve curves shown in FIG. 14. In FIG. 14, in turn, the delivery height H, ie the pressure above the rotational speed n of the drive motor 30, is plotted. The pressure curves AP _CO i _d and AP _ho t correspond to the pressure curve curves, which are shown in Fig. 13. It lacks only the constant form AP _pre , so that the pressure curve AP _h ot is not shifted in the diagram up, but how the pressure curve AP _CO i _d begins at zero point. However, both curves have a different pitch, which in turn, as described above by different impeller diameter of the wheels 26 and 28 is achieved. Due to the fact that the differential pressure at the impellers 26 and 28 changes differently when the speed changes, the hydraulic resistances change, resulting in a mixing region 42 between the two pressure curves with a resulting differential pressure. The higher output pressure AP _CO id of the impeller 26 acts as a hydraulic resistance in the second flow path through the impeller 28 at the mixing point 20. The hydraulic resistance results from the pressure difference between the output pressures of the impellers 26 and 28 at the mixing point 20. As in 14, this pressure difference between the pressure curves APcoid and APhot (the mixing area 42) is speed-dependent. Ie. Also, the hydraulic resistance, which acts in the flow path through the impeller 28 can be varied by changing the speed, so that the flow through the impeller 28 and thus the flow of heated heating medium can be changed. Even so, a change in the temperature on the output side of the mixing point 20 and thus a temperature control by changing the speed of the rotational speed n of the drive motor 30 is possible.

FIG. 5 shows an exemplary embodiment which represents a variant of the exemplary embodiment shown in FIG. 2. There are the two wheels 26 and 28 are formed in the form of a double impeller. Ie. the impeller 26 is formed by a first blade ring and the impeller 28 by a second blade ring of the same impeller. The variation of the mixing ratio at the mixing point 20 by changing the rotational speed n of the drive motor 30 takes place in the same manner as described with reference to FIGS. 3 and 13. In this embodiment, in addition to upstream of the wheels 26 and 28 in the flow line 18, a flow regulating valve R _ho t and in the return line 1 6 a Flow regulating valve R _CO id provided. These are manually adjustable valves, with which a default can be made before the described speed control is performed. The default setting is preferably carried out in such a way that initially the rotational speed of the drive motor 30 is set so that a sufficient flow is achieved by the bottom floor 2. Ie. it is the rotational speed of the wheels 26 and 28 initially adjusted so that a matched to the system, ie the hydraulic resistance of the system differential pressure is generated. Subsequently, the manual flow regulating valves R _ho and R _CO id SO are set so that at the given speed at the temperature sensor 36, a desired temperature setpoint value is reached. This temperature setpoint value can be, for example, a temperature setpoint value which is predetermined by a heating curve at the current outside temperature. By manual presetting, a balance between different hydraulic resistances in the flow line 18 and the return line 16 is achieved. After this presetting, the temperature control can then be carried out by means of speed control by means of the control device 34, wherein only small speed changes for temperature adaptation are required, as is apparent from the diagram in FIG. 13. Such valves for presetting can also be used in the other described embodiments.

FIG. 4 shows a third variant of a heating system with a mixing device according to the invention. Also in this heating system, a boiler 4 is provided with a downstream circulating pump unit 6. Furthermore, a floor heating 2 or a floor heating circuit 2 to be supplied is provided. Again, a mixing device 44 is present, in which a heating medium flow from a flow 18, which extends from the boiler 4 with a heating medium flow from a return line 1 6 from the return of the underfloor heating 2 is mixed. In this exemplary embodiment, the mixing device 44 in turn has a circulation pump unit 46 with an electric drive motor 30. This drive motor 30 is also controlled in its rotational speed by a control device 34, which can be integrated directly into the drive motor 30 or arranged directly on the drive motor 30 in an electronics housing. As in the preceding embodiments, the control device 34 is communicatively connected to a temperature sensor 36, which is located on a supply line 38 to the Fußbo- circle 2 out, so that it detects the flow temperature of the heating medium, which is supplied to the underfloor 2. Thus, a temperature-dependent speed control can also be performed in the circulating pump unit 36 in the manner described above. [34] Of the embodiments described above, the embodiment of FIG. 4 differs in that the circulatory pump unit does not have two parallel impellers, but rather impeller parts 48 and 50 connected in series. The impeller parts 48 and 50 can be connected as two separate non-rotatably connected impellers Be trained wheels so that they are driven to rotate about the common drive motor 30. However, the impeller parts 48, 50 are particularly preferably designed as an impeller, which has at least one second inlet opening in a radial middle area between a first central inlet opening and the outlet opening, as described in greater detail below. In this exemplary embodiment, this second inlet opening forms the mixing or orifice point 52, at which the two liquid flows or heating medium flows from the return line 16 and the feed line 18 are mixed. Via the impeller part 48, the heating medium flow from the return line 16 experiences a first pressure increase ΔΡ 1 upstream of the mixing point 52. Running grinding 18 undergoes an increase in pressure AP _pre through the circulating pump assembly 6. With this form, the heating medium is injected at the orifice point 52 into the medium of the heating medium, which relieves the impeller 48. The Mündpunkf 52 and the second impeller 50 form a second Sfrömungsweg by which the Heizmediumsfrom from the lead grinding 18 and further downstream of the mouth point 52 and the Heizmediumsfrom from the Rücklaufleifung 16, which previously experienced in a first flow path in the impeller 48, a pressure increase has, flow. In the impeller 50, the mixed medium of heat undergoes another pressure increase ΔΡ2.

[35] In this configuration as well, the mixing ratio between the medium of the heating medium from the return grinding 16 and the heating medium flow from the flow line 18 can be changed by changing the speed, as will be described in more detail with reference to FIG. In FIG. 15, in turn, the pressure curves in the form of the delivery height H are plotted against the rotational speed n of the drive motor 30. In the diagram in FIG. 15, the constant pre-pressure AP _pre generated by the circulating pump unit 6 can be recognized as a horizontal line. Furthermore, the two speed-dependent pressure curves API and ΔΡ2 are shown. In this case, the pressure curve .DELTA.Ρ2 has a steeper course than the pressure curve API, ie the pressure .DELTA.Ρ2 increases more with increasing the speed than the pressure API. Between the pressure curve ΔΡ1 and the prepressure AP _pre there is a mixing region 54 in which different mixing ratios can be realized. With increasing pressure API, which experiences the Heizmediumsfrom from the return grinding 1 6 in the impeller 48, the hydraulic resistance increases in the second flow path to the impeller 50 at the mixing point 52. It forms a back pressure at the mixing point 52, which as hydraulic shear Resistance for the Heizmediumsfrom is used, which enters from the lead grinding 18 in the mixing point 52. The higher the back pressure at the mixing point 52, the lower the flow through this second flow path through the orifice point 52, ie, the smaller is the heating medium flow, which enters from the flow line 18 in the mixing point 52 and thus the second flow path. By exceeding the pre-pressure AP _pre by the pressure ΔΡ1 the hot water flow, ie the heating medium flow from the flow line 18 is completely switched off. Thus, by changing the speed, the mixing ratio can be changed. In the second impeller part 50, the mixed heating medium flow then experiences the pressure increase to the pressure ΔΡ2.

[36] This arrangement has the advantage that the pressure AP _pre , which is generated by the circulation pump unit 6, does not have to be reduced since the mixture of the two heating medium flows takes place at a higher pressure level, namely at the level of the pressure ΔΡ 1. As a result, energy losses in the mixing device 44 are reduced.

[37] Hereinafter, the structural design of the mixing devices 22 and 44 will be described in detail with reference to Figures 6 to 12. FIGS. 6 to 9 show a mixing device which is used as a mixing device 22 in the exemplary embodiments according to FIGS. 2, 3 and 5. FIGS. 10 to 12 show a mixing device 44, as used in the exemplary embodiment according to FIG. 4.

[38] The embodiment according to FIGS. 6 to 9 shows an integrated circulating pump mixing device, ie a circulating pump unit with integrated mixing device or a mixing device with integrated circulating pump unit. The circulating pump unit has, in a known manner, an electric drive motor 30 to which an electronics housing or terminal box 56 is attached. In the electronics housing in this embodiment, the control device 34th arranged. The electric drive motor has a stator or motor housing 58, inside which the stator 60 of the drive motor 30 is arranged. The stator 60 surrounds a gap pot or a can 62, which separates the stator space from a centrally located rotor space. In the rotor space of the rotor 64 is arranged, which may be formed for example as a permanent magnet rotor. The rotor 64 is connected via a rotor shaft 66 to the impeller 68, so that the rotor 64 rotatably drives the impeller 68 as it rotates about the rotation axis X. The impeller 68 is formed in this embodiment as a double impeller and combines the wheels 26 and 28, as described with reference to FIGS. 2 and 5. The impeller 68 has a central suction mouth 70, which opens into a first blade arrangement or a first blade ring, which forms the impeller 26. Thus, a first flow path through the impeller 68 is defined by the suction port 70 and the impeller 26. The impeller 26 is formed closed and has a front cover plate 72, which merges into a suction mouth 70 limiting collar. On the front cover plate 72, a second blade ring is arranged or formed, which forms the second impeller 28. The second impeller 28 has an annular suction port 74 on the inlet side, which annularly surrounds the suction port 70. The second suction port 74 forms a second inlet opening of the impeller 68. The impeller 28, starting from the second suction port 74, a second flow path through the impeller 68. Both the impeller 26 and the impeller 28 have circumferentially on the outlet openings, which in a pressure chamber 76 of a pump housing 78 open.

[40] The pump housing 78 is connected to the motor housing 58 in a conventional manner. The pressure chamber 76 in the interior of the pump housing 78 opens into a discharge port 80, to which in the embodiment 2, 3 and 5, the supply line 38 would connect to the underfloor 2. Since both wheels 26 and 28 open into the pressure chamber 76, the mixing point 20 described with reference to FIGS. 2, 3 and 5 is located on the outlet side of the impeller 68 in the pressure chamber 76 of the pump housing 78.

[41] The first suction mouth 70 of the impeller 68 is in the pump housing 78 with a first suction line 82, which starts at a first suction port 84, in connection. This first suction nozzle 84 is axially aligned with the discharge nozzle 80 along an installation axis which extends normal to the axis of rotation X. At the suction port 84, the return line 1 6 is connected in the embodiments of FIGS. 2, 3 and 5. In this embodiment, in the suction pipe 82, moreover, a flow regulating valve R _CO i _{d is} arranged, as shown in Fig. 5. [42] From the suction port 84, which forms a first input, a first flow connection through the pump housing 78 is defined via the suction line 82, the suction port 70, the first impeller 26, the pressure chamber 76 and the discharge port 80. The pump housing 78 also has a second suction port 86, which forms a second input. The second suction nozzle is connected in the interior of the pump housing 78 via a connecting channel 88 with an annular space 90 on the suction side of the impeller 68. The annular space 90 surrounds a ring element 92 on the outside. The ring element 92 is inserted into the suction chamber of the pump housing 78 and engages with its annular collar with the collar surrounding the suction mouth 70, so that a sealed flow connection is created from the suction channel 82 into the suction mouth 70. Externally, the ring element 92 is surrounded by the annular space 90, so that the ring element 92 separates the flow path to the suction mouth 70 from the flow path to the second suction mouth 74. Into the pump Housing is further used an annular sealing element 94 which rests against the inner circumference of the pump housing 78 and comes into sealing contact with the outer periphery of the impeller 68. In this case, the sealing element 94 in the outer peripheral region of the second suction mouth 74 with the impeller 68 in sealing contact, so that it separates the suction region on the inlet side of the suction mouth 74 of the pressure chamber 76 in the pump housing.

[43] In the flow path from the second suction port 86 to the connecting channel 88, a check valve 96 is additionally arranged, which prevents a backflow of liquid into the flow line 18. At the second suction port 86, the flow line 18, as shown in Figs. 2, 3 and 5, connected.

With the circulating pump unit 24 shown with the integrated mixing device 22, a temperature control of the heating medium which is supplied to the underfloor heating circuit 2 can be achieved by changing the speed of the drive motor 30, as can be seen with reference to FIGS. 2, 3 and 5 as well as FIGS 14 has been described.

[45] Via the flow regulation valves R _CO id and R _hot , a presetting can be carried out as described with reference to FIG. 5. In this embodiment, the flow regulating valves Rcoid and Rhot are formed as rotatable valve members 98 which are respectively inserted into a cylindrical accommodating space. By rotation, the valve elements 98 reach different degrees into the suction line 82 or cover the connecting channel 88, so that the free flow cross section in the first or second flow path can be changed by rotation of the corresponding valve element 98. [46] FIGS. 10 to 12 show an exemplary embodiment of the circulation pump assembly 46 with the mixing device 44, as described with reference to FIGS. 4 and 15. The mixing device 44 and the circulation pump assembly 46 also represent an integrated structural unit. The drive motor 30 with the attached electronics housing 56 corresponds in a structure to the drive-on motor 30, as described with reference to FIGS. 7 to 9. Also, the pump housing 78 'in its construction substantially corresponds to the above-described pump housing 78. A first difference is that the pump housing 78' has no flow regulating valves R _ho t and R _CO i _d , it being understood that also in In this second embodiment, such Durchflußreguliervenfile R could be provided, as described above. A second difference is that the second Saugsfutzen 86 'has an external thread in this embodiment. However, it is to be understood that also the Saugstufzen 86 could be configured according to the previous embodiment or the Saugsfutzfen 86 'could also have an internal thread.

[47] In the second embodiment, an impeller 100 is connected to the rotor shaft 66. This impeller 100 has a central suction port 102, the peripheral edge of which is in sealing engagement with the ring member 92, so that a flow connection of the first Saugstufzen 84 is created in the impeller 100. The impeller 100 has only one blade ring, which defines a first flow path from the suction mouth 102, which forms a first Eintriftsöffnung to the outer periphery of the impeller 100. This first Sfrömungsweg opens into the pressure chamber 76, which is connected to the Druckstufzen 80. Surrounding the ring element 92, in turn, there is an annular space 90, into which the connecting channel 88 opens from the second suction gap 86. The impeller 100 has a front cover disk 104. In this opening 106 are excluded. forms, which form second inlet openings. These openings 106 open into the flow channels 108 between the impeller blades. In this case, the openings 106 open into the flow channels 108, viewed radially with respect to the axis of rotation X, in an area between the suction mouth 102 and the outer circumference of the rotor 100. the openings 106 open into a radial middle region of the first flow path through the impeller 100. The openings 106 and the flow channels 108 form with their sections radially outside of the openings 106 form second flow paths which the impeller part 50, as described with reference to FIG , corresponds. The impeller part 78 is formed by the radially inner impeller part, ie in the flow direction between the suction mouth 102 and the openings 106. The openings 106 face the annular space 90, so that heating medium can enter into these openings 106 via the connection channel 88. The outlet side of the openings 106 thus lies in the flow channels 108 in this embodiment, the mixing point 52 of FIG. 4th

[48] The impeller 100 has on its outer periphery, d. H. on the outer circumference of the cover plate 104 on an axially directed collar 1 10, which 'abuts the inner periphery of the pump housing 78 and thus the annular space 90 against the pressure chamber 76 seals. With the circulating pump unit 46 with integrated mixing device 44 shown in FIGS. 10 to 12, a temperature control of the heating medium flow which is supplied to the underfloor heating circuit 2 can be carried out, as described above with reference to FIGS. 4 and 15.

[49] In the case of the three solutions described by way of example according to the invention, a regulation of the temperature has been described by adjusting the mixing ratio solely by changing the speed. However, it should be understood that such a flow temperature regulation could also be realized in combination with an additional valve R _ho t in the flow line 18 and / or a valve R _CO i _d in the return line 1 6. In this case, the valves R _ho t or R _CO i _{d may} optionally be coupled together or may be formed together as a three-way valve. An electric drive of these valves could be controlled by a common control device 34, which also controls the speed of the drive motor 30. Thus, by controlling the valves together with the control of the rotational speed of the drive motor 30, the mixing ratio and thus the temperature in the flow line for underfloor heating can be regulated or controlled. As a result, on the one hand, a larger control range can be achieved. On the other hand, the losses can be reduced by larger valve opening degrees. For example, the speed can only be increased for a short time in order to mix in an increased amount of heated heating medium.

[50] The invention has been described using the example of a heating system. It should be understood, however, that the invention may equally be used in other applications in which two streams of liquid are to be mixed. A possible application is, for example, a system for setting a service water temperature, as is customary in pressure booster pumps for service water supply, in so-called shower booster pumps.

LIST OF REFERENCE NUMBERS

2 underfloor heating, underfloor heating circuit

4 boilers

6 Circulation pump unit

8 circulating pump unit

10 impeller

12 drive motor

14 mixing point f

16 return grinding 18 supply line

R _CO i _d Flow control valves

20 mixing punkf

22 Mixer 24 Circulation pump unit

26, 28 impellers or arrangements of impeller blades

30 drive motor

34 control device

36 temperature sensor

38 Supply line for underfloor heating 2

39 intersection

40, 42 mixing area

44 mixing device

46 Circulation pump assemblies 48, 50 Impeller parts or flow paths 2 mixing point

4 mixing area

6 electronics housing

8 motor housing

60 stator

62 can

64 rotor

66 rotor shaft

68 impeller

70 suction mouth

72 front cover disc

74 second suction mouth, second inlet opening

76 discharge nozzle

78, 78 'pump housing

80 discharge nozzles

82 suction line

84 suction nozzle

86 second suction nozzle

88 connection channel

90 annulus

92 ring element

94 sealing element

96 check valve

98 valve elements

100 impeller 102 suction mouth

104 cover disk

106 openings, second openings

108 flow channels

1 10 collar

s flow direction

X axis of rotation

Claims

Claims Circulating pump unit with a first input (84), an output (80), an electric drive motor (30) and at least one of the drive motor (30) driven impeller (68, 100), which at least a first, in a connection between the first Inlet (84) and the outlet (80) located flow path (26; 48) for increasing the pressure of a liquid,

characterized in that

the circulation pump assembly has a second input (86) and the at least one impeller (68; 100) has at least one second flow path (28; 50) for increasing the pressure of a liquid which is in communication from the second input (86) to the output (80 ) is located.

Circulating pump unit according to Claim 1, characterized in that the at least one first flow path (26; 48) and the at least one second flow path (28; 50) are formed in a common impeller (68; 100) or in at least two impellers rotatably arranged relative to one another.

Circulating pump unit according to claim 1 or 2, characterized in that the at least one second flow path (50) is formed by a portion of the at least one first flow path (48).

Circulating pump unit according to one of the preceding indents, characterized in that

the at least one impeller (68; 100) has a suction mouth (70; 102) as the first inlet opening, from which the at least one first flow path (26; 48) leads to an exit side of the outlet Impeller (68; 100) extends, and that the impeller (68; 100) at least a second inlet opening (74; 106) which in the direction of flow through the impeller (68; 100) between the suction mouth (70; 102) and the outlet side is located and connected to the second input (86) of the circulating pump unit.

Circulating pump unit according to claim 4, characterized in that the at least one second inlet opening (106) opens into the at least one first flow path (48, 50), the section (50) of the at least one first flow path between the at least one second inlet opening (106). and the exit side forms the at least one second flow path (50).

Circulating pump unit according to claim 4 or 5, characterized in that the impeller (100) has a plurality of second inlet openings (106).

Circulating pump unit according to claims 5 and 6, characterized in that a plurality of first flow paths (28; 108) are formed between impeller blades of the at least one impeller (100) and at least one second inlet opening (74; 106) opens into each of the first flow paths between the impeller blades.

Circulating pump unit according to one of claims 4 to 7, characterized in that the at least one second inlet opening (74; 100) is formed in a cover disc (72; 104) surrounding the suction mouth (70; 102). Circulating pump unit according to one of claims 4 to 8, characterized in that the suction mouth (70; 102) is in engagement with a stationary ring element (92), in the interior of which a flow connection (82) opens from the first inlet (84).

Circulating pump unit according to claim 9, characterized in that an annular space (90) is formed on the outer circumference of the ring element (92), into which a flow connection from the second inlet (86) opens, and in that the at least one second inlet opening (106) engages this annular space (90 ) is facing.

Circulating pump unit according to one of the preceding claims 4 to 10, characterized in that the impeller (68; 100) is radially outside the at least one second inlet opening (106) in sealing engagement with a part of a surrounding pump housing.

Circulation pump unit according to one of the preceding claims, characterized in that in a flow connection between the second input (86) and the at least one impeller (68; 100) a valve (R) for adjusting the flow through this flow connection is arranged.

Circulating pump unit according to claim 12, characterized in that the valve has an electric drive for changing the valve position, wherein the electric drive is preferably a stepper motor.

14. Circulation pump unit according to one of the preceding claims, characterized by a control device (34) which is designed for adjusting the rotational speed of the drive motor (30). 15. Heating system with a first circulating pump unit according to one of the preceding claims, characterized by a second circulating pump unit (6), which upstream of the second input (86) of the first circulating pump unit (24; 46) is located, wherein the second circulating pump unit (6) is preferably a Centrifugal pump unit is, which has a

Control device is adjustable in its speed.

Heating system according to claim 15, characterized in that a control device (34) is provided, which is designed such that it the first circulating pump unit (24; 46) and / or the second circulating pump unit (6) and / or in the flow path of the second The input (86) controls the valve located at least one impeller (68; 100) to adjust a mixing ratio of the flows from the first input (84) and the second input (86) in the first circulating pump unit (24; 46).