DOUBLE PUMP

Description

Technical field

[0001] The invention relates to a double pump with two centrifugal pumps, each with impellers arranged therein for conveying a fluid and a suction manifold branching into two individual manifolds for sucking in the fluid, which individual manifolds are connected to a respective suction area of ​​the impellers. Background of the invention

[0002] In order to convey large volumes while using smaller electric motors and pumps simultaneously, or to create redundancy in the conveying circuit, double pumps are preferably used. In such double pumps, also called twin pumps, two impellers are arranged in a housing, with each impeller driven by an electric motor to form a single pump. A suction manifold is arranged upstream of the impellers, through which a fluid, in particular water, is sucked in at a suction area of ​​the impellers in order to convey it. To feed both impellers, the suction manifold is usually divided symmetrically into two individual manifolds connected to the respective suction area of ​​the impellers.

[0003] However, the symmetrical design of the suction manifold, due to its curvature, leads to a pre-swirl caused by the impellers rotating in the same direction: on one side, a pre-swirl that rotates against the impeller's direction of rotation, and on the other side, a pre-swirl that rotates in the same direction as the impeller. The different conditions on the two sides of the double pump result in different behavior in terms of power consumption and hydraulic performance for each side of the double pump. Previous flow guides could only compensate for the pre-swirl with considerable flow losses. Furthermore, optimal flow to the impeller cannot be achieved with flow guides located directly in front of the impeller.Differences in flow velocity as well as angular deviations will inevitably remain and will be detrimental to the high hydraulic performance actually desired.

[0004] DE 197 33 941 A1 describes a guide device which is connected to a bend or two bends arranged one behind the other in a channel through which a fluid flows, with one or more guide ribs arranged in front of the only or second bend and running essentially parallel to the plane of curvature of the only or second bend, the leading edge or edges of which divide the cross-sectional area of ​​the channel in such a way that partial areas with a predetermined amount of partial flows are created, wherein the guide rib or ribs change the cross-sections of the partial areas in their further course in such a way that the flow leaves the outlet of the only or second bend without swirl or with a desired swirl.

[0005] DE 295 11 718 U1 describes a double centrifugal pump with two impellers, each of which has an inlet and an outlet for the pumped medium, wherein at least in one inlet a guide device is arranged, through which the pumped medium flows and which has surfaces that are arranged approximately perpendicular to the plane of rotation of the impeller. Description of the invention

[0006] Based on this situation, it is an object of the present invention to provide a double pump whose individual centrifugal pumps are characterized by a hydraulic performance that is as identical as possible.

[0007] The object of the invention is achieved by the features of the independent claim. Advantageous embodiments are specified in the subclaims.

[0008] Accordingly, the object is achieved by a double pump with two centrifugal pumps, each with impellers arranged therein for conveying a fluid and a suction manifold branching into two individual manifolds for sucking in the fluid, which individual manifolds are connected to a respective suction area of ​​the impellers, wherein in each individual manifold a flow guide element is provided at a distance from the respective impeller, which flow guide element divides the fluid flowing into the individual manifold into two partial flows and extends in the flow direction of the fluid towards the impeller in a tapered manner in height, wherein the flow guide element is divided into two in such a way thatthat the first part facing the inflowing fluid rests on both sides against an inner wall of the individual bend at its longitudinal edges extending in the flow direction of the fluid, and the second part facing the impeller rests on the individual bend at an edge extending in the flow direction of the fluid and tapers in height towards the impeller at its opposite edge.

[0009] A key aspect of the invention thus lies in the shape and arrangement of the flow guidance element in the individual bend, which, on the one hand, leads to a division of the rotational vortex into two smaller rotational vortices in the flow channel and, on the other hand, to the generation of a rotational vortex that minimizes or eliminates the remaining counter-vortex. This is because the proposed flow guidance element manipulates the flow earlier in the individual bend compared to designs known from the prior art in order to achieve maximum equalization of the different flow velocities up to the impeller. In this way, the flow quality in the inlet area of ​​the impeller is optimized in terms of pre-swirl, angular error, and irregularity. With regard to pre-swirl, an average circumferential speed can be easily controlled, eliminated, or even transformed into pre-swirl in the opposite direction.The flow guidance elements eliminate the need for complex control of the individual centrifugal pumps, which is otherwise often required with dual-pump pumps, to optimize hydraulic performance. Furthermore, the proposed shape of the flow guidance element allows for the particularly simple manufacture of a pump housing for the dual-pump or its suction manifold. As a result, the proposed dual-pump achieves an almost identical or even identical and high hydraulic performance, particularly in terms of delivery head, power consumption, and / or efficiency, of both centrifugal pumps and thus of the dual-pump.

[0010] A double pump is generally a fluid machine that uses rotary motion and dynamic forces to pump predominantly liquids. In a centrifugal pump, in addition to tangential acceleration of the liquid, the medium, centrifugal force occurring in radial flow is used for pumping, so that such pumps are also referred to as centrifugal pumps. During normal operation of the double pump, a housing of a motor of the centrifugal pump can be arranged above a pump housing, in which the impeller, driven by the motor via the motor shaft, is provided for pumping the fluid. The motor housing can be fixedly connected to the pump housing and / or can be designed as a single piece. Preferably, the motor shaft projects from the motor housing into the pump housing on one drive side and / or the impeller is fixedly connected to the motor shaft on the drive side.

[0011] The fluid preferably comprises a liquid such as water or another liquid medium such as wastewater. The fluid may comprise solids such as contaminants of any kind, in particular feces, sediment, dirt, sand, or even small pieces of wood, brushwood, textiles, or rags, or the like. The motor housing and / or the pump housing are preferably made of metal, in particular cast iron or stainless steel, and / or plastic.

[0012] The proposed double pump is preferably used in heating circuits or similar, in particular to cover peaks in demand for pumped heating water. For this purpose, the double pump can be controlled to a constant or predefined variable pressure by changing the speed of the individual centrifugal pumps. The control can, for example, operate both centrifugal pumps synchronously, i.e. at the same speed, to cover the required flow rate. Alternatively, initially only one of the two centrifugal pumps can be used to cover the required flow rate. As soon as this centrifugal pump has reached its maximum speed, the second centrifugal pump is switched on and continuously increased to cover even larger flows, while the first centrifugal pump continues to run at maximum speed.The suction manifold preferably has a round, oval, or oval-like cross-section, which cross-section can vary from the branching of the suction manifold into the individual manifolds up to the respective impeller. The suction manifold preferably has a heart-shaped configuration, with the individual manifolds preferably extending perpendicularly or approximately perpendicularly from the branching.

[0013] In state-of-the-art double pumps with multiple centrifugal pumps whose flow rates are added on the outlet side, differences in the flow rates of the individual centrifugal pumps exist, even with structurally identical drives, the same impellers and synchronous, i.e. identical, speed and direction of rotation. This is because the pipe routing within the pump housing requires adaptation to the common pressure line. Pressure nozzle channels in the pump housings often have different courses and arrangements. As a result, the two centrifugal pumps in a double pump differ in their hydraulic properties, resulting in differences in the flow rates of the centrifugal pumps despite the same speed and design.If one centrifugal pump delivers more than the other, a kind of feedback effect occurs because the increased performance of one centrifugal pump impairs the delivery capacity of the other centrifugal pump on the shared pressure side. This causes the delivery rate of the other centrifugal pump to be further reduced. In other words, the delivery flow of the other pump is pushed away from the delivery flow of one pump. However, the proposed solution can easily eliminate this problem, or at least significantly reduce it, without the need for complex electronic control or other structural modifications beyond the flow control element.

[0014] The flow guide element is preferably flat and can be rectangular or rectangular in shape, at least in part or entirely. The flow guide element is preferably arranged in the individual manifold such that its flat extent is aligned parallel, approximately or at least partially parallel to the flow direction. The flow guide element preferably divides the inflowing fluid into two equal or approximately equal partial flows. The division can also generate vortices based on the resulting vortices, so that more fluid can flow through one of the resulting channels than through the other channel. At the end of the flow guide element facing the flow, at which the flow is divided, the flow guide element is preferably arranged parallel to the flow.At the end of the flow guide element facing the impeller, the latter can be aligned at an angle to the flow in order to generate a swirl.

[0015] Distanced from the impeller means in particular that the flow guide element is arranged closer to the branching of the individual manifolds and / or at the end of the suction manifold opposite the impeller than to the impeller. Spaced can also mean that the flow guide element is arranged at least 1, 2, 3, 4, 5, 7.5, 10 or more cm away from the impeller. Spaced can further mean that in the case of an individual manifold that is generally bent essentially orthogonally directly in front of the impeller for connection to the impeller, the flow guide element is arranged in the flow direction upstream of the bend, in particular 1, 2, 3, 4, 5, 7.5, 10 or more cm upstream of the bend. In other words, spaced means in particular that the flow guide element is arranged as far away as possible from the impeller in the individual manifold. This distance can vary depending on the arrangement of the impellers and the specific hydraulic conditions.The remote arrangement allows any remaining vortex in the area between the flow guide element and the impeller to settle. This allows the flow to be influenced early in the suction manifold's extension, achieving the greatest possible equalization of the different flow velocities up to the impeller.

[0016] Tapering in its height perpendicular to the flow direction means, in particular, that the height decreases toward the impeller at a constant or variable rate. Thus, the height at the end of the flow guide element facing the branching can be equal to the diameter of the individual bend, while the height at the end facing the impeller can be only a fraction of the diameter. Likewise, the height in the direction of fluid flow can initially be constant and then taper.

[0017] According to a preferred development, the flow guide element is configured and arranged in the individual bend such that the partial flows in the flow direction behind the flow guide element are swirl-free or exhibit a desired swirl. In this respect, it is possible, for example, to influence the swirl behind the flow guide element by designing and arranging it in the individual bend, for example by varying the longitudinal extent, an angle at the end of the flow guide element to the flow, the distance from the impeller, and / or the taper, namely to eliminate it or to achieve a desired swirl, for example, a counter-swirl.

[0018] In another preferred embodiment, the individual bend is L-shaped in side view with two legs arranged essentially orthogonally to one another, wherein the shorter leg is connected to the impeller and the flow guide element is arranged in the longer leg. In other words, in such an individual bend that is L-shaped in side view, the flow guide element can be arranged in the longer L-leg and thus spaced from the impeller. Preferably, the flow guide element does not extend into the shorter leg and / or ends in the flow direction before the bend between the longer leg and the shorter leg.

[0019] According to the invention, the flow guide element is divided into two parts such that the first part facing the inflowing fluid rests on both sides against an inner wall of the individual bend at its longitudinal edges extending in the flow direction of the fluid, and the second part facing the impeller rests on the individual bend at an edge extending in the flow direction of the fluid and tapers in height towards the impeller at its opposite edge. In this way, the flow guide element can extend on at least one longitudinal edge along its entire extent in the flow direction, in particular touching the inner wall of the individual bend. Up to the end of the second part facing the impeller, the height can have dropped continuously to zero or, for example, can still amount to 40 to 60% of the diameter of the individual bend until shortly before the end.In the first part, the flow guide element preferably extends along its entire length at a constant height and / or a height corresponding to the diameter of the individual bend. This allows the rotation to be divided into two smaller rotations consisting of a vortex and a pre-swirl. The second part, with its decreasing height, can generate a counter-vortex that minimizes or completely eliminates any remaining rotation after the first part.

[0020] According to a preferred embodiment, the length ratio of the two parts in the flow direction of the fluid is 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, or 4:1. In absolute terms, the first part can extend, for example, 2 cm in the flow direction, while the second part can extend, for example, 3 cm in the flow direction, thus the ratio can be 2:3. Other ratios, for example, odd ratios, are also possible. In another preferred embodiment, the height of the first part equals the diameter of the individual bend.

[0021] According to a further preferred embodiment, the flow guide element tapers in an S-shape in height. In another preferred development, the S-shaped tapered flow guide element extends approximately constantly between its S-shaped ends with a height of ≥ 40% and ≤ 60%, in particular 50%, of the diameter of the individual bend. Particularly preferably, only the second part of the flow guide element tapers in an S-shape in height, while the first part has a constant height along its longitudinal extent in the flow direction. Particularly preferably, the S-shaped end facing the first part has a significantly larger radius than the other S-shaped end, so that the flow guide element initially drops sharply in height at the transition from the first part to the second part and can then, for example, remain approximately constant in height all the way to the other S-shaped end.The ratio of the radii is, for example, 2:1, 3:1, 4:1, 5:1 or 10:1.

[0022] According to a further preferred embodiment, the flow guide element extends in an S-shape in plan view of its edge extending in the flow direction of the fluid. The S-shaped end facing the impeller preferably has a significantly larger radius than the S-shaped end facing the branch. The ratio of the radii is, for example, 2:1, 3:1, 4:1, 5:1 or 10:1. Likewise, the S-shaped end facing the branch can taper flat, i.e., be approximately flat, for example, while the S-shaped end facing the impeller is curved. The S-shaped end facing the impeller is preferably curved towards the inner wall of the individual bend.In this context, according to another preferred development, it is preferred that a transverse edge of the flow guide element facing the inflowing fluid is arranged closer to an inner wall of the individual manifold than an opposite transverse edge of the flow guide element facing the impeller.

[0023] According to a further preferred embodiment, a flow-guiding element-free region is provided in the individual bend between the impeller and the flow-guiding element, and the length ratio of the flow-guiding element and the flow-guiding element-free region in the flow direction of the fluid is 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, or 4:1. The flow-guiding element-free region preferably extends over 1, 2, 3, 4, 5, 7.5, 10, or more cm, as explained above. In another preferred embodiment, the flow-guiding elements of the individual bends are designed and / or arranged symmetrically. The flow-guiding elements can also be designed differently. In this way, different hydraulic properties of the individual centrifugal pumps, impellers, and / or individual bends, in particular different power lengths, line cross-sections, number and angle of the line bends of the individual bends, etc., can be compensated without the need for often complex electronic control to compensate for the different hydraulic properties.

[0024] According to a further preferred embodiment, the flow guidance elements of the individual bends are arranged adjacent to one another in the branching region in such a way that the partial flow of one individual bend is unaffected by the flow guidance element of the other individual bend. This means that, although the flow guidance elements do not touch one another, they can be arranged as close to one another as possible without influencing the partial flow of the other individual bend. Such an arrangement, i.e., particularly away from the impeller and "close" to one another, can positively influence the flow quality in both individual bends, resulting in an improved characteristic curve for the double pump.

[0025] In another preferred embodiment, the flow guide element is designed in a rib-like manner. Particularly preferably, the flow guide element is designed as a flat material and / or is injection-molded or cast in one piece and / or together with the intake manifold, in particular from gray cast iron, investment casting, or polyurethane. Short description of the drawings

[0026] The invention is explained in more detail below with reference to the attached drawings using preferred embodiments.

[0027] The drawings show Fig. 1 a schematically illustrated double pump with two individual manifolds according to a preferred embodiment of the invention in plan view, Fig. 2 a single manifold of the Fig. 1 shown double pump according to the preferred embodiment of the invention in a partially opened perspective view, and Fig. 3 a single manifold of the in Fig. 1 illustrated double pump according to a further preferred embodiment of the invention in a partially opened perspective view. Detailed description of the implementation examples

[0028] Fig. 1 shows a double pump 1, also called a twin pump, according to a preferred embodiment of the invention, represented schematically only by a frame. The double pump 1 has two centrifugal pumps 2 arranged therein, also represented schematically only by a dashed frame. Each of the two centrifugal pumps 2 has an impeller 3 arranged therein for conveying a fluid, such as water in particular, which impeller is also represented schematically only by a dashed frame. Furthermore, the double pump 1 has a suction manifold 4 for sucking in the fluid, which is connected in a fluid-tight manner to the respective suction areas of the impellers 3. The heart-shaped suction manifold 4 branches off into two individual manifolds 5, which are each connected to the impellers 3.

[0029] In each individual manifold 5, as can be seen in detail from the partially cutaway individual manifolds 5 Figs. 2 and 3As can be seen, a rib-like, flat flow guide element 6 is provided, by which the fluid flowing into the individual manifold 5 is divided into two essentially equal partial flows. Alternatively, a division in a ratio of 55:45, 60:40, 70:30 or exactly 50:50 can also take place. The flow guide element 6 can be made of a flat material, but in the present case is injected or cast in one piece with or into the individual manifold 5 and is provided within it at a distance from the respective impeller 3. The flow guide element 6 extends in the flow direction 7 of the fluid, indicated by an arrow, towards the impeller 3, wherein its height tapers towards the impeller 3.

[0030] Specifically, the flow guide element 6 is designed in two parts, with a first part 8 facing the inflowing fluid extending rectangularly in the individual bend 5, so that the transverse side facing the inflowing fluid is oriented perpendicular to the flow direction 7 of the fluid, and the flow direction 7 of the fluid runs essentially parallel to the flow direction 7. The longitudinal edges of the first part 8 contact an inner wall of the individual bend 5 along their entire extent, so that the flow guide element 6 divides the fluid flow essentially equally. Accordingly, the height of the flow guide element 6 corresponds to the diameter of the individual bend 5, whereby the individual bend 5 can have not only a round cross-section but also an oval cross-sectional shape and / or a cross-sectional shape that changes along its extent.

[0031] A second part 9, which faces the impeller 3, is integrally connected to the first part 8. The second part 9 tapers in an S-like manner in height in the flow direction 7 of the fluid, starting at the end of the first part 8 with a height corresponding to the diameter of the individual bend 5 and decreasing in the flow direction 7. In contrast, a longitudinal edge of the second part 9, like that of the first part 8, rests in contact with the inner wall of the individual bend 5 along its extension in the flow direction 7. The length ratio of the two parts 8, 9 is 1:1 in the present case, although other ratios such as 1:4, 1:3, 1:2, 2:3, 3:2, 2:1, 3:1 or 4:1 are also conceivable.

[0032] As is particularly evident from Fig. 2 As can be seen, the S-shaped tapered flow guide element 6 extends between its S-shaped ends approximately constantly with a height of ≥ 40% and ≤ 60%, in this case 50%, of the diameter of the individual bend 5. while in Fig. 2 the S-shaped ends have a radius of the same size, in contrast, the radius of the S-shaped end in the transition region of the first and second part 8, 9 is considerably larger than the radius of the S-shaped end of the transverse edge of the flow guide element 6 facing the impeller 3. In this respect, the height in the flow direction 7 in the transition region of the first and second part 8, 9 initially drops sharply, subsequently remains approximately constant in the range of ≥ 40% and ≤ 60% of the diameter of the individual bend 5, and then finally drops to zero at the transverse edge facing the impeller 3.

[0033] In plan view of its longitudinal edge extending in the flow direction 7 of the fluid, the flow guide element 6 extends in an S-shape, as can be seen from Fig. 1 While the S-shaped end or the transverse edge of the flow guide element 6 facing the branching is barely bent, the S-shaped end or the transverse edge of the flow guide element 6 facing the impeller 3 has a considerably larger bending radius, so that the transverse edge is oriented towards the inner wall of the individual bend 5. As can also be seen from Fig. 1 As can be seen, the flow guidance elements 6 of the two individual manifolds 5 are designed symmetrically and arranged symmetrically in the individual manifolds 5.

[0034] Basically, the flow guide element 6 is arranged at a distance from the impeller 3, namely oriented closer to the branching than to the impeller 3, although not explicitly shown in Fig. 1shown. In this respect, a flow-guiding element-free area is provided between the impeller 3 and the flow-guiding element 6. The length ratio in the flow direction between the flow-guiding element-free area and the flow-guiding element 6 is 1:2 in the present case. Accordingly, the two flow-guiding elements 6 are arranged close to one another in the region of the branching, so that the partial flow of one individual bend 5 is unaffected by the flow-guiding element 6 of the other individual bend 5. For this purpose, the flow-guiding element 6 of one individual bend 5 can be arranged in the region of the branching adjacent to a virtual hose in the individual bend 5 formed by the flow of the other individual bend 5.

[0035] The described embodiments are merely examples; the scope of the invention is defined by the following claims. List of reference symbols

[0036] Double pump1 Centrifugal pump2 Impeller3 Suction manifold4 Single manifold5 Flow guide element6 Flow direction7 First part8 Second part9

Claims

1. A double pump (1) with two centrifugal pumps (2) each with impellers (3) arranged therein for conveying a fluid and an intake manifold (4), branching into two individual manifolds (5), for drawing in the fluid, which individual manifolds (5) are connected to a respective suction region of the impellers (3), wherein a flow guidance element (6) is provided in each individual manifold (5) at a distance from the respective impeller (3), which flow guidance element (6) divides the fluid flowing into the individual manifolds (5) into two partial streams and, in its height, extends in a tapering manner towards the impeller (3) in the flow direction (7) of the fluid, and the flow guidance element (6) is divided into two in such a way that the first part (8) facing the inflowing fluid bears on both sides at its longitudinal edges extending in the flow direction (7) of the fluid against an inner wall of the individual manifold (5) and the second part (9) facing the impeller (3) bears at an edge extending in the flow direction (7) of the fluid against the individual manifold (5) and tapers at its opposite edge in its height towards the impeller (3).

2. The double pump (1) according to the preceding claim, wherein the flow guidance element (6) is configured and arranged in the individual manifold (5) such that the partial streams in the flow direction (7) after the flow guidance element (6) are swirl-free or have a desired swirl.

3. The double pump (1) according to any one of the preceding claims, wherein the individual manifolds (5) in side view is L-shaped with two legs arranged substantially orthogonally to one another, with the shorter leg being connected to the impeller (3) and the fluid guidance element (6) being arranged in the longer leg.

4. The double pump (1) according to any one of the preceding claims, wherein a length ratio of the two parts (8, 9) in the flow direction (7) of the fluid is 1:4, 1:3, 1:2, 1:1, 2:1, 3:1 or 4:1.

5. The double pump (1) according to any one of the preceding claims, wherein the height of the first part (8) equals the diameter of the individual manifold (5).

6. The double pump (1) according to any one of the preceding claims, wherein the flow guidance element (6) tapers in an S-shaped manner in its height.

7. The double pump (1) according to the preceding claim, wherein the S-shaped tapering flow guidance element (6) extends between its S-shaped ends approximately constantly with a height of ≥40% and ≤60%, in particular 50%, of the diameter of the individual manifold (5).

8. The double pump (1) according to any one of the preceding claims, wherein the flow guidance element (6) in plan view extends in an S-shape at its edge extending in the flow direction (7) of the fluid.

9. The double pump (1) according to any one of the preceding claims, wherein a transverse edge of the flow guidance element (6) facing the inflowing fluid is arranged closer to an inner wall of the individual manifold (5) than an opposite transverse edge of the flow guidance element (6) opposite the impeller (3).

10. The double pump (1) according to any one of the preceding claims, wherein a flow guidance element-free region is provided in the individual manifold (5) between the impeller (3) and the flow guidance element (6) and a length ratio of the flow guidance element (6) and the flow guidance element-free region in the flow direction (7) of the fluid is 1:4, 1:3, 1:2, 1:1, 2:1, 3:1 or 4:1.

11. The double pump (1) according to any one of the preceding claims, wherein the flow guidance elements (6) of the individual manifolds (5) are formed and / or arranged symmetrically.

12. The double pump (1) according to any one of the preceding claims, wherein the flow guidance elements (6) of the individual manifolds (5) are arranged adjacently closely next to one another in the region of the branching, in such a way that the partial stream of one individual manifold (5) is uninfluenced by the flow guidance element (6) of the other individual manifold (5).

13. The double pump (1) according to any one of the preceding claims, wherein the flow guidance element (6) is formed in a rib-like manner.