EP2591237B1 - Centrifugal pump - Google Patents

Description

The invention relates to a centrifugal pump, comprising a running gear and a housing surrounding it, each with a pressure and suction connection, a method for producing such a centrifugal pump, and a kit for such a centrifugal pump.

Centrifugal pumps are known in numerous designs. Housing shape, impeller details and seal have been the subject of extensive research and development in recent decades. This has led to a continuous improvement, so that very well adapted centrifugal pumps are available for many different applications. The robust technology is used in plant and mechanical engineering, in water supply and in agricultural irrigation.

The EP 0 206 031 A1 shows the housing of a centrifugal pump, which is lined with a liner. The liner describes the inner shape of the housing, while the stability is contributed by an outer shape.

The DE 2103331 describes a method for forming a composite body from an elastomeric surface layer and a synthetic resin backing layer which ensures mechanical strength. Pump housings can be produced using this method.

While various hydraulically relevant details of the centrifugal pumps described above are designed specifically for the respective application, the basic components, such as the pump housing, are often designed similarly. For larger water pumps, a housing made of cast metal, usually gray cast iron, is typically used, which is simple to manufacture and process, inexpensive and durable. Likewise, the shafts used are typically steel shafts, which are often manufactured using common methods. The disadvantage of conventionally manufactured pumps, however, is that the finished pump is relatively heavy and bulky when transported to the end user.

The following invention has for its object to provide a centrifugal pump comprising a running gear, consisting of an impeller, a seal, and optionally a shaft, and a housing surrounding it, each with a pressure and suction connection, the disadvantages mentioned above being overcome should. In addition, a method for producing such a centrifugal pump is to be developed.

The solution to this problem provides that the housing surrounding the running gear is constructed as a composite part, a first thin-walled layer specifying the inner shape of the housing, at least a second layer producing the stability of the housing. The pump according to the invention makes it possible to carry out only the first thin-walled layer, which specifies the internal shape and / or fluid-contacted structure of the housing, at the factory, while the second layer is only applied to the end customer. If the material for the formation of the second shift is available on site at the end customer, there is no need to transport it over long distances, which means that transport costs can be saved to a considerable extent. The hydraulically optimized shape of the pump housing required for the use of the centrifugal pump is completely predetermined by the first layer. The second layer can be applied on site. This second layer serves to mechanically stabilize the housing, which is why it can also be applied by the end customer as long as the required minimum strengths are achieved, which is ensured according to the invention by sufficiently large security factors. In the A valve is installed in the first layer, which maintains and simultaneously displays the pressure of the medium. In particular, in addition to the pure pressure values, a display also shows the housing configuration or the operating point set with it. The applied pressure can be displayed directly without any additional aids. Different pump configurations can be set directly by the corresponding internal pressure, since in particular the size and shape of the pump chamber around the impeller can be set differently by applying the media pressure. After the pump has been completed, the display can be used to monitor the operating status of the pump.

A configuration according to which the first layer is composed of individual segments representing the housing shape enables further savings in the transport of the individual parts necessary for the pump. This also enables exact adaptation to the hydraulic requirements placed on the centrifugal pump. By combining different standardized individual parts, different housings can be manufactured easily and inexpensively.

The first layer is molded from an elastomer. This creates a first layer, which specifies the inner contour of the pump housing, which can be packaged very compactly. For use as the first layer of the housing according to the invention, the first layer can be filled with a medium, as a result of which it obtains its intended shape, which is fixed with the second layer.

In a variant of the elastomeric first layer, a space is provided within the first layer which can be shaped by filling with a medium. This is particularly useful when the pressure of the medium is greater than the ambient pressure. For this purpose, the elastomeric first layer is made with areas of different thickness during production, whereby deformations can be achieved which determine the hydraulic properties of the housing.

A particularly simple form of design provides a propellant charge, which is supplied with the necessary medium under appropriate pressure, so that it is not necessary to build up the internal pressure on site using external compressors or pumps.

In a particularly advantageous manner, sensors for monitoring the operation of the pump are attached to the outside of the first layer and are hidden directly in the pump housing after application of the second layer. In this way, wear and corrosion of the inner shell can be demonstrated, for example.

There is also the option of connecting the first layer in a pressure-tight manner to the stationary parts of the carriage and to the connections. This has the advantage that the tightness of the pump is already established by the connection of the first layer to the pump components provided according to the invention. A later sealing is no longer necessary in this embodiment.

In a further embodiment, the second layer consists of a material plastically molded onto the first layer. In order to obtain the best possible bond between the first and the second layer, it is necessary for the material of the second layer to adapt to the surface of the first layer. A material is suitable for this, which is poured onto the first layer in the liquid state and then solidifies there.

Plastics, metals, mineral materials or material mixtures are suitable as plastically formable material. As already shown, it is advantageous to choose a material for the second layer that can be poured liquid onto the first layer. For this purpose, casting resins with different fillers, liquid metal, for example, are suitable, whereby the heat resistance of the first layer must be taken into account, or concrete. These materials are available worldwide, with the choice of each Pump requirements such as the delivery head and the cost is dependent.

The plastically formable material is advantageously reinforced by reinforcements. This increases the stability of the housing, and at the same time the thickness of the housing can be reduced.

In a further embodiment, customary surface activations such as roughening or application of primers are provided for improved adhesion of the second layer to the first. This improves the bond between the materials.

In a further embodiment, the material of the first layer is made of two layers. The second layer is then placed between the two layers of the first layer. This allows the external shape of the pump to be specified more precisely and the second layer is also protected against media on the outside.

Ingredients that may be obtained from renewable raw materials are suitable as material for the production of the second layer. Fibers, binders or fillers can be obtained from different plants. These are readily available in many places, which is why the production is particularly cheap because local resources can be used both in the cultivation and in the extraction of the substances.

A method for producing a centrifugal pump according to the invention provides for aligning all tolerance ranges with respect to the shaft in a first step. In a second step, the first layer is fixed in a pressure-tight manner with respect to the tolerance ranges, in a third step the first layer is filled with a medium from the inside and pressurized, and in a fourth step the second layer is applied. It is advantageous here compared to previous manufacturing processes to reverse the process, in which the desired hydraulic structure is usually worked out into or out of a predetermined support structure. Linings and coatings are known, but not the manufacture of the often delicate hydraulic structure with subsequent reinforcement.

In an embodiment of the method, a hydraulically advantageous shape is produced in the first layer in the third step by applying a predetermined pressure. The advantage here is that the internal geometry of the housing can be specified very precisely by means of the pressure which is given to the medium in the third step, as a result of which the flow guidance is optimally adapted to the centrifugal pump properties. The pressure is read directly from the valve in the first layer. In addition to the pure pressure values, the housing configuration or the operating point set with it can be read on the scale. The first thin-walled layer is additionally coated with a second layer, whereby the necessary stiffening of the housing is achieved. When covering the supporting structure with the second layer, the first layer forms a component of the composite material as lost formwork. When using a centrifugal pump according to the invention, the second layer offers protection against the harsh environmental conditions and absorbs the attacking forces. Depending on the design of the centrifugal pump, it is particularly advantageous for maintenance purposes to design the formwork in two parts, so that the housing can be opened for maintenance purposes.

In a further embodiment of the method, the second layer is solidified after the application, in particular by hardening, firing or sintering. Depending on the material used, further processing of the housing can bring additional advantages for the housing. This step can make the second layer more stable against mechanical or chemical influences. The connection between the first and second layers can also be improved.

With regard to the aforementioned construction of the centrifugal pump, a kit for producing a centrifugal pump is provided according to the invention, which comprises different components.

The kit according to the invention comprises the rotor and the first layer, the rotor consisting of the impeller and seal. The advantage here is that a simple and inexpensive basic package for producing a functional centrifugal pump is put together. The missing components are obtained from local suppliers when the centrifugal pump is built. The costs for transporting the kit can thus be kept low. Local resources can be used in close proximity to the end user. This is particularly advantageous in countries with a comparatively low technical infrastructure.

In a further embodiment, the rotor also contains a shaft. Since the manufacture of the shaft is subject to a demanding dimensional tolerance, it is advantageous to include it in the kit. In addition, the other components of the centrifugal pump can already be pre-assembled on the shaft.

It is also possible to add a shaft bearing to the kit. The advantage here is that the shaft is stably supported. The stability of the pump is significantly increased by a shaft bearing. If the shaft bearing is already pre-assembled on the shaft, no additional assembly and adjustment effort is required here.

The design of the connections of the centrifugal pump as flanges enables standardized pipes to be connected to the centrifugal pump.

In a further embodiment, the outer packaging of the kit serves as a casting mold for the second layer. The advantage here is that the outer packaging can be adapted to the requirements of a casting mold. Both the surface and the stability of the outer packaging can be adapted to the requirements of the casting process by the manufacturer of the kit. For example, markings for certain dimensions, such as the position of the shaft or connecting flanges or the maximum fill level for the material of the second layer, can be made.

Further embodiments result from the combination of those shown so far and are therefore not explained further here.

Figur 1

einen vormontierten Pumpenbausatz, die

Figur 2

den Bausatz in Bearbeitung, die

Figur 3

eine erste Ausführung einer fertigen Pumpe und die

Figur 4

eine zweite Ausführung einer fertigen Pumpe.

Exemplary embodiments of the invention are shown in the drawings and are described in more detail below. They show

Figure 1

a pre-assembled pump kit, the

Figure 2

the kit in progress, the

Figure 3

a first version of a finished pump and the

Figure 4

a second version of a finished pump.

The Figure 1 shows an embodiment of a centrifugal pump according to the invention. An impeller 2 is attached to the left end of a shaft 1. A seal 3 is connected directly to the impeller 2. In the Figure 1 a bellows mechanical seal is shown. The part of the seal 3, which is adjacent to the impeller 2, is fixed to the shaft and rotates with it. The stationary part of the mechanical seal connected to a housing is arranged on the far right. At some distance from the seal 2, two bearings 4 are arranged on the shaft 1. With this kit for the centrifugal pump, all parts that have special dimensional tolerance requirements are pre-assembled to fit. A first layer 5 envelops the parts and forms the inner wall of the pump housing. To form the different sections of the pump housing, the first layer 5 is connected directly to some pump parts, the first layer 5 also being able to be made up of several parts, the individual parts being arranged pressure-tight between two stationary parts of the rotor. In the area of the impeller 2, the first layer 5 is connected directly to the stationary part of the seal 3. This simple and very effective connection saves additional sealants, such as O-rings. Also pre-assembled and firmly connected to the first layer 5 in the Figure 1 the two split rings 6 and 7 shown. These are also connected to the impeller 2 by an easily detachable connection. These connections serve as an assembly aid. Until the centrifugal pump is completed, the split rings are firmly in place so that the required dimensional accuracy is ensured. Before using the centrifugal pump for the first time, this connection must be released so that the impeller can rotate freely. The connections of the pump to the first layer 5 are also provided in the region of the impeller 2. In the example shown, a suction port 8 is an extension to the shaft 1 and a pressure port 9 shown. Both nozzles are firmly connected to the first layer 5. The connection of the first layer 5 to the bearings 4 creates two further spaces, between the seal 3 and the first bearing 4 and between the two bearings 4. At the right end, a shaft end 10 remains outside the first layer, to which the pump drive is connected becomes. In the Figure 1 it is shown that the first layer 5 consists of a deformable material which can be applied closely to the shaft 1. This allows the semi-finished centrifugal pump to be packaged very small for shipping.

The Figure 2 shows a semi-finished centrifugal pump according to the third step of the method for producing a centrifugal pump according to the invention. The first layer is filled with a medium from the inside and pressurized. The connections for pressure equalization between the individual areas, as well as the closures of the pressure and suction ports are in the Figure 2 not shown. The internal shape of the housing is thus clearly defined. Depending on the choice of the material of the first layer 5, there is the possibility of influencing the hydraulic properties of the pump chamber by the pressure applied to the medium. Different geometries of the housing can be produced in the area around the impeller.

The Figure 3 shows a first embodiment of a finished pump. In this case, that was in Figure 2 Pour the semifinished component shown completely in a shipping box (not shown) with a second layer 11. This form of the second layer 11 is the easiest to manufacture, since no requirements are placed on the external appearance of the pump, apart from a material-dependent minimum wall thickness. For example, concrete can be used as the material for the second layer. Materials such as clay, which is mixed with fibers, synthetic resin or comparable castable materials, which solidify, are also suitable for this form of reinforcement. Additional reinforcement elements on the stationary parts 3, 4, 6, 7, 8, 9 are not shown in this figure. These are firmly connected to the stationary parts and protrude into the region of the second layer 11, as a result of which the stationary parts are positioned and held Parts in the finished centrifugal pump are improved.

The Figure 4 shows a second embodiment of a finished pump. In order to also specify the outer shape of the pump housing, an additional jacket layer 12 was provided in this embodiment, which also consists of flexible material, so that the advantage of compact packaging is retained during transport. To reinforce the pump housing, the second layer 11 was introduced between the first layer 5 and the cladding layer 12 in this embodiment. This variant of the centrifugal pump according to the invention makes it possible to implement designs which take into account the limited space available at the place of use and which have a higher resource efficiency.

Reference list

1. 1st wave
2. 2nd impeller
3. 3. Seal
4. 4th camp
5. 5. first layer
6. 6. Split ring
7. 7. Split ring
8. 8. Suction nozzle
9. 9. Pressure port
10. 10. Shaft end
11. 11. second layer
12. 12. Cladding layer

Claims (18)

1. Centrifugal pump, comprising a running assembly and a casing which surrounds the latter and has in each case one pressure-side connector and suction-side connector, wherein the casing is constructed as a composite part, wherein a first elastomeric layer predefines the internal shape of the casing and, during production, is formed with regions of differing thickness, wherein at least one second layer establishes the stability of the casing, wherein the first layer (5) is connected in a pressure-tight manner to components (2, 3, 4) arranged on a shaft (1) and to the connectors (8, 9),
   characterized in that
   a valve having a pressure value indicator is installed into the first layer (5).
2. Centrifugal pump according to Claim 1, characterized in that the first layer (5) is composed of individual segments providing the casing shape.
3. Centrifugal pump according to either of Claims 1 and 2, characterized in that the space within the first layer (5) is able to be shaped by being filled with a medium.
4. Centrifugal pump according to one of the preceding claims, characterized in that the valve in the first layer (5) holds and indicates the medium pressure, wherein, in particular, an indicator indicates the pressure values alone, wherein, in particular, the pressure values are associated with a specific casing configuration or an operating point set therewith.
5. Centrifugal pump according to Claim 4, characterized in that provision is made of a propellant which provides, under corresponding pressure, the medium required for the filling of the first layer (5).
6. Centrifugal pump according to one of the preceding claims, characterized in that the second layer (11) consists of a material which is formed plastically onto the first layer (5).
7. Centrifugal pump according to Claim 6, characterized in that the plastically formable material is a plastic, a metal, a mineral material or a material mixture.
8. Centrifugal pump according to Claim 6 or 7, characterized in that the plastically formable material is strengthened by reinforcements.
9. Centrifugal pump according to one of the preceding claims, characterized in that, for improved adhesion of the second layer (11) to the first layer (5), surface activation means are provided.
10. Centrifugal pump according to one of the preceding claims, characterized in that the material of the first layer (5) is of two-ply form.
11. Method for producing a centrifugal pump according to one of the preceding claims, characterized in that, in a first step, all the tolerance ranges are aligned with respect to the shaft (1), in that, in a second step, the first layer (5) is fixed in a pressure-tight manner with respect to the tolerance ranges, in that, in a third step, the first layer (5) is filled from the inside with a medium and is subjected to a pressure, and in that, in a fourth step, the second layer (11) is applied.
12. Method according to Claim 11, characterized in that, in the third step, through application of a predefinable pressure, a hydraulically advantageous shape for the first layer (5) is produced.
13. Method according to Claim 11 or 12, characterized in that the second layer (11), after being applied, is also solidified, in particular by curing, baking or sintering.
14. Construction kit for a centrifugal pump according to one of Claims 1 to 10 produced according to one of Claims 11 to 13, characterized in that the construction kit contains the running assembly of the centrifugal pump and the first layer (5), wherein the running assembly comprises an impeller (1) and a seal.
15. Construction kit according to Claim 14, characterized in that the running assembly additionally comprises a shaft (1).
16. Construction kit according to Claim 14 or 15, characterized in that the running assembly additionally comprises a shaft bearing arrangement (4).
17. Construction kit according to Claim 14, 15 or 16, characterized in that the connectors are designed as flanges (8, 9).
18. Construction kit according to one of Claims 14 to 17, characterized in that an outer packaging of the construction kit serves as a casting mould for the second layer (11).

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