Double pump assembly

Abstract

The invention relates to a double pump unit (1) comprising a first and a second centrifugal pump with a common pump housing (2) in which a pump chamber (3, 4) of the first and second centrifugal pump is formed, each of which has a pressure channel (5, 6) opening into a common valve chamber (7) which transitions into an outlet channel (8) and in which a valve (9) is arranged, which is pivotably held by a retaining section (10) in a receiving chamber (11) of the pump housing (2) and selectively closes one or the other pressure channel (5, 6). According to the invention, the valve (9) is held floating without shafts in the receiving chamber (11).

Description

[0001] The invention relates to a double pump unit comprising a first and a second centrifugal pump with a common pump housing in which a pump chamber of the first and second centrifugal pump is formed, of which in each case a pressure channel opens into a common flap chamber, which merges into a common outlet channel and in which a flap is arranged, which is held pivotably by a holding section in a receiving space of the pump housing and selectively closes one or the other pressure channel.

[0002] Double pump units of this design are generally known, for example from German patent applications DE 195 11 170 A1 or DE 10 2014 006 258 A1, whereby the double pump units disclosed therein comprise centrifugal pumps with parallel pump axes. The flap, also known in technical jargon as a double pump flap, is pivotably mounted on a shaft in the form of a pin that is mounted externally in the pump housing. Both the pin and the pump housing are specially machined for this purpose. The pump housing has a special threaded hole open to the outside, through which the pin is inserted into the pump housing. The pin, in turn, has an external thread at one axial end with which it is screwed into the threaded hole in the pump housing. To achieve tightness, the thread is self-sealing and is also bonded into the threaded hole with an adhesive. In addition, the threaded hole is closed with a plug.It goes without saying that manufacturing this bearing for the double pump flap is technically complex. Furthermore, due to the threaded hole in the pump housing, there is always a certain, albeit minimal, risk of leakage, which is important for the long service life of a double pump.

[0003] Finally, the assembly of the double pump flap in the pump housing is laborious and difficult, since it must first be inserted through the narrow outlet channel into the flap chamber, then aligned with the hollow profile of its insertion end in alignment with the threaded hole and held in this position in order to insert the pin into the hollow profile in this holding position.

[0004] Types of double pump units in which the pump axes are aligned and opposite each other are shown in German patent DE 2 237 108 B1 and international application WO 2019 / 192984 A1. In DE 2 237 108 B1, a flap, called a check valve there, is arranged between the pump outlets and pivotally mounted on a shaft, so that the aforementioned disadvantages exist. The publication WO 2019 / 192984 A1 discloses a flap in the pump housing that can move freely pivotably within an acute angle between the cross-sectional planes of the outlet openings until it reaches a contact position at the outlet opening of the first spiral casing or at the outlet opening of the second spiral casing, respectively, and can block the respective outlet opening. The publication does not disclose whether and how the flap is held in the pump housing to remain between the outlet openings.

[0005] The object of the present invention is to overcome the aforementioned disadvantages and to provide a double pump unit with a pump housing in which the flap can be mounted in a simple manner and without additional components.

[0006] This object is achieved by a double pump unit having the features of claim 1. Advantageous further developments are specified in the subclaims and are explained below.

[0007] According to the invention, the flap is held in the receiving space with the holding section in a shaft-free, floating manner. In other words, the holding section sits loosely in the receiving space. There is therefore no shaft about which the flap can pivot. The geometric axis about which the flap can be pivoted is not fixed as in the prior art, but rather can change its position relative to the pump housing. The flap can therefore pivot about an axis whose position can be changed. In addition, there is all-round play around the holding section, which enables relative movement of the flap to the pump housing in all spatial directions. The floating mount leads to greater mobility of the flap due to this play alone. In addition, the mobility is increased due to the lack of a shaft, because this always created frictional resistance when the flap was pivoted. The receiving space is different from the pressure channels.Consequently, the holding section is not subjected to any flow.

[0008] A further advantage of the clearance around the retaining section is that the inner wall of the receiving space does not require remachining. Rather, it can remain rough due to manufacturing. For example, the pump housing can be made of gray cast iron using a lost sand mold core to form the receiving space, which generally results in very rough, uneven inner surfaces. However, this is irrelevant for the floating bearing according to the invention.

[0009] The flap can thus continue to close one or the other pressure channel unhindered, but no additional components are required to hold it in place, such as a separate shaft or pin, an adhesive, or a plug to close the bore in the pump housing. This bore can also be omitted. Thus, the double pump unit according to the invention eliminates manufacturing and processing steps, particularly on the pump housing, simplifying the manufacturing process. At the same time, the lack of a bore eliminates the risk of leakage.

[0010] According to the invention, the receiving space opens towards the flap chamber via an opening that is narrower than the holding section. In order to insert the flap into the receiving space, the holding section is elastic enough to be compressible to a width that is less than or equal to the width of the opening. In other words, when the flap is inserted into the receiving space, the holding section is pressed / squashed in order to pass through the opening. Once the opening has been overcome, it returns to its natural shape without any force being applied, so that it engages behind the opening. In this way, a loose positive fit is achieved. This not only enables simple and quick installation of the flap in the pump housing. The flap is also securely held in the receiving space and can be easily removed again, or the holding section can be pulled out of the receiving space again, since the positive fit can be easily released again.When pulled out, the holding section is compressed or pressed together again so that it can overcome the narrower opening again.

[0011] No special tools are required to insert the valve. If necessary, simple needle-nose pliers can be used if your hand cannot reach through the outlet opening of the outlet channel, i.e., the pressure port. To further facilitate insertion, the opening to the receiving chamber can be aligned with the outlet opening of the outlet channel.

[0012] In order to maintain the elasticity of the holding section, it can be provided in one embodiment that the holding section is made of an elastic material, in particular a material that is so soft that it can be sufficiently compressed to overcome the opening to the receiving space even if the holding section is of solid construction, ie if the holding section is made of solid material.

[0013] Preferably, the holding section is formed by a hollow body, in particular a hollow profile. This also results in elasticity of the holding section, as it is easier to deform, so the material does not need to be as soft as in the case of a holding section made of solid material.

[0014] In one design variant, the cross-section of the holding section and the receiving chamber can each be circular. This circular shape has the advantage that even if solids should accumulate in the receiving chamber over time, the flap with its holding section continues to glide smoothly over these solid deposits at any pivoting angle.

[0015] Alternatively, the holding section can be oval or shaped like an "O." Furthermore, it doesn't necessarily have to be closed. For example, a C-shape, T-shape, or V-shape are also possible, as long as the holding section engages behind the opening to the receiving space.

[0016] It is advantageous if the retaining section has a clearance of at least 1 mm on all sides. In the case of a circular shape, the receiving space then has an inner diameter that is at least 2 mm larger than the outer diameter of the retaining section. Such a large clearance has the advantage that solid particles that can accumulate at the bottom of the receiving space over time do not impair the movement of the flap.

[0017] According to one embodiment, the receiving space can be approximately symmetrical and have a first and a second side wing, wherein the holding section is shaped such that it lies at least predominantly in the second side wing when one pressure channel is closed and at least predominantly in the first side wing when the other pressure channel is closed, and the one pressure channel and the second side wing on the one hand and the other pressure channel and the first side wing on the other hand are each located on opposite sides of an axis of symmetry of the receiving space. Such an arrangement creates a maximum degree of flexibility for the geometry of the pump housing. For example, the aforementioned receiving space with the side wings can be narrower in the direction of the flap chamber than in the direction of the side wings.Thus, the floating holder according to the invention can also be used in pump housings in which a circular cross-sectional design of the receiving space and the holding section is not possible due to the position of the pump chambers and / or their pressure channels and / or due to the required pivot angle (position and opening angle) of the flap.

[0018] The holding section can have a width, viewed in cross-section, that is greater than its height. Such a flap can advantageously be located in a receiving space that is narrower toward the flap chamber than toward its side wings.

[0019] In order to completely eliminate the risk of leakage, the wall of the receiving chamber can be free of passages, especially holes to the outside.

[0020] The flap is particularly easy to manufacture if the retaining section is formed integrally with a flap body that closes one or the other pressure channel. In particular, the retaining section and flap body can be cast from the same material in a single casting. However, it is also possible to manufacture the flap body separately and then join it to the retaining section, for example, by means of a form fit and / or an adhesive bond. This has the advantage that different materials can be used for the flap body and the retaining section. The form fit can, for example, be implemented in the manner of a dovetail.

[0021] Further features, properties, effects, and advantages of the invention are explained in more detail below with reference to exemplary embodiments and the accompanying figures. The reference symbols contained in the figures retain their meaning from figure to figure. In the figures, reference symbols always designate the same or equivalent components, areas, directions, or locations.

[0022] It should be noted that, in the context of this description, the terms "have," "comprise," or "include" in no way exclude the presence of other features. Furthermore, the use of the indefinite article for an object does not exclude its plural form. The following show: Fig. 1: a radial cross section through a pump housing of a first double pump unit according to the invention Fig. 2: a front view of the flap in the pump housing according to Figure 1 Fig. 3: a side view of the flap in the pump housing after Figure 1Fig. 4: a perspective view of the flap in the pump housing according to Figure 1 Fig. 5: a radial cross section through a pump housing of a second double pump unit according to the invention Fig. 6: a front view of the flap in the pump housing according to Figure 5 Fig. 7: a side view of the flap in the pump housing after Figure 5 Fig. 8: a perspective view of the flap in the pump housing according to Figure 5

[0023] Figure 1 shows a section through a pump housing 2 of a double pump unit 1 of a first embodiment along a radial plane perpendicular to the two pump axes. The other components of the double pump unit 1 are not shown. Figures 2 to 4 show a flap 9 used in the double pump unit 1 in different views.

[0024] The double pump unit 1 has two electric motor-driven centrifugal pumps, whose pump axes are parallel in this design variant. The centrifugal pumps can be designed as wet-running pumps, so that the respective motor shaft simultaneously forms the pump shaft. The two pump shafts each carry an impeller at their respective ends, which is arranged in a respective pump chamber 3, 4. The two pump chambers 3, 4 are in Figure 1 They are part of the pump housing 2, so that the pump housing 2 is a common component of both centrifugal pumps.

[0025] The pump housing 2 has an inlet opening 17 leading into an inlet channel 16 located radially to the pump axes, which divides into two suction channels 13, 14, each of which opens axially into one of the two pump chambers 3, 4. One of the impellers is arranged in each outlet opening. From the two pump chambers 3, 4, a pressure channel 5, 6 in the pump housing 2 opens into a common flap chamber 7, which merges into an outlet channel 8. The outlet channel 8 has an outlet opening 13 located in the so-called pressure port. Correspondingly, the inlet opening 17 is located in a so-called suction port. The suction and pressure ports are aligned coaxially here, so that the double pump unit 1 forms a so-called inline pump, which is connected to a hydraulic piping system via the suction and pressure ports.

[0026] A flap 9, also referred to as a double pump flap, is arranged in the flap chamber 7. It is pivotally mounted by a holding section 10 in a receiving chamber 11 of the pump housing 2 and can thus selectively close the first or second pressure channel 5, 6. The receiving chamber 11 is separate from the pressure channels 5, 6. Consequently, the holding section 10 is not subjected to flow. The receiving chamber 11 opens into the flap chamber 7.

[0027] The flap 9 is mounted in the receiving chamber 11 in a floating manner. In contrast to the prior art, the flap 9 is not mounted on a shaft extending through the receiving chamber 11. Consequently, the flap 9 is held without a shaft, which means that the holding section 10 is not stationary relative to the pump housing 2. Thus, the axis around which the flap 9 can be pivoted can be changed relative to the pump housing 2.

[0028] There is also a play around the holding section 10 on all sides, which allows a relative movement of the flap 9 to the pump housing 2 in all spatial directions. The play is in Figure 1 , whereby, however, in this illustration showing the double pump unit 1 in its non-operational state, the flap 9 rests on the bottom of the receiving space 11 due to its own weight. It should be emphasized that this contact between the holding section 11 and the pump housing 2 is nevertheless understood as play due to the lack of fixation of the flap 9 in the pump housing 2, since the flap 7 in any case has the possibility of floating.

[0029] The all-round play is achieved by the fact that the outer dimensions of the holding section 10 are smaller in every spatial direction than the inner dimensions of the receiving space 11. As in Figure 1As can be seen, this embodiment has a holding section 10 with a circular cross-section, with the receiving space 11 also being circular in cross-section. Consequently, to achieve all-round clearance, the outer diameter of the holding section 10 is smaller than the inner diameter of the receiving space 11, for example, by 5 mm, so that a clearance of 2.5 mm exists. This has the advantage that the inner surface of the receiving space, which is very rough due to the manufacture of the pump housing from cast metal using a sand core, does not need to be machined.At the same time, the respective sealing surface 25 of the pump housing 2 around the mouth opening of the corresponding pressure channel 5, 6 in the flap chamber 7 is dimensioned sufficiently large laterally so that the flap 9, by its contact with the sealing surface 25, completely closes the corresponding pressure channel 5, 6 even if, due to its mobility, it is sometimes positioned further up, sometimes further down, sometimes further to the right or sometimes further to the left.

[0030] The receiving chamber 11 opens toward the flap chamber 7 via an opening 12 through which the holding section 10 is inserted into the receiving chamber 10. The opening 12 is delimited laterally by a web 23, 24, so that the opening 12 lies between these two webs 23, 24. A first of these webs 23 is formed between the first pressure channel 5 and the receiving chamber 11, and the second of these webs 24 is formed between the second pressure channel 6 and the receiving chamber 11. The end faces of these webs 23, 24 each form part of the sealing surface 25, which surrounds the mouth opening in a ring. The sealing surface 25 forms, so to speak, a stop for the flap 9.

[0031] In order for the flap 9 with its holding section 10 to remain in the receiving space 11, the opening 12 is narrower than the holding section 10 or the holding section 10 is wider than the opening 12, so that it engages behind the two webs 23, 24. To ensure its insertion through the opening 12, the holding section 11 is elastic in such a way that it can be compressed to a width that is less than or equal to the width of the opening 12. This is the case in the embodiment according to Figure 1 This is achieved by making the holding section 10 from an elastic material, for example, EPDM, preferably with a hardness between 60 and 90 Shore. In addition, the holding section 10 is designed as a hollow body. In other words, it consists of an annular wall that encloses a particularly cylindrical cavity 19. Deformation of the holding section 10 thus occurs through movement of the annular wall into the cavity 19.

[0032] Depending on the elasticity of the material, the wall thickness can be narrower or thicker. In other words, the material can be harder if the wall thickness is thinner, or thicker if the material is softer. The preferred wall thickness is between 3 and 5 mm.

[0033] The flap 9 is inserted through the outlet opening 13 of the outlet channel 8, which, to simplify this, is aligned with the opening 12 of the receiving space 11. Pliers, particularly needle-nose pliers, can be used for insertion. If the flap 9 with the holding section 10 is increasingly pressed against the webs 23, 24, its annular wall deflects inward into the cavity 19, so that its width is reduced and it can slide past the webs 23, 24 into the receiving space 11, where the wall relaxes back into its original circular shape. The flap 9 can also be pulled out of the receiving space 11 in the same way.

[0034] Figures 2 to 4 show flap 9 according to Figure 1 in front ( Fig. 2 ), side ( Fig. 3 ) and perspective view ( Fig. 4 ). The flap 9 consists of a flap body 18 and the holding section 10. These are cast in one piece from the same material. The flap body 18 is tongue-shaped in the form of a plate with a flap front side 26 and a flap rear side 27, which lie parallel to each other. The outer edge area of ​​the flap front side 26 and the flap rear side 27 form a flap-side sealing surface in order to come into contact with the respective sealing surface 25 on the side of the pump housing 2. The width of the flap body 18 is greater than the axial length of the holding section 10, so that the flap body 18 protrudes axially on both sides relative to the holding section 10, as Figures 2 and 4 illustrate.

[0035] Figure 5show a pump housing 2 according to a second embodiment of a double pump unit 1 according to the invention. It differs from the first variant essentially in the position and shape of the receiving space 10 and in the shape of the flap 9, which in the Figures 6 to 8 is shown. Furthermore, the suction and discharge ports are formed by flanges.

[0036] Although the receiving chamber 11 according to this second embodiment is also symmetrical, it has first and second side wings 21, 22, which are opposite one another with respect to an axis of symmetry 20 and form an approximately heart shape. The holding section 10 is shaped such that, when the first pressure channel 5 is closed, it lies predominantly in the second side wing 22, and when the second pressure channel 6 is closed, it lies predominantly in the first side wing 21. The first pressure channel 5 and the second side wing 22, on the one hand, and the second pressure channel 6 and the first side wing 21, on the other, are located on opposite sides of the axis of symmetry 20 of the receiving chamber 11.

[0037] The holding section 10 has a width (B) viewed in cross section that is greater than its height H, compare in particular Fig. 7The cavity 19 has the overall cross-section of an elongated hole. Another difference between the flap 9 and the first embodiment is that the holding section 10 has an identical width to the flap body 18.

[0038] In both design variants, the wall of the receiving space 11 is free of any passages to the outside, so that there is no risk of leakage due to the flap 9 used.

[0039] It should be noted that the foregoing description is given merely by way of example for illustrative purposes and in no way limits the scope of the invention. Features of the invention referred to as "may," "exemplary," "preferred," "optional," "ideal," "advantageous," "optionally," "suitable," or the like are to be considered purely optional and do not limit the scope of the invention, which is defined exclusively by the claims. List of reference symbols

[0040] 1 Double pump unit 2 Pump housing 3 First pump chamber 4 Second pump chamber 5 First pressure channel 6 Second pressure channel 7 Valve chamber 8 Outlet channel 9 Valve 10 Holding section 11 Receiving chamber 12 Opening 13 Outlet opening 14 First suction channel 15 Second suction channel 16 Inlet channel 17 Inlet opening 18 Valve body 19 Cavity 20 Symmetry axis 21 First side wing 22 Second side wing 23 First web 24 Second web 25 Sealing surface 26 Valve front side 27 Valve back side

Claims

1. Dual pump assembly (1) comprising a first and a second centrifugal pump with a joint pump casing (2), in which respectively one pump chamber (3, 4) of the first and second centrifugal pump is formed, from which respectively one pressure channel (5, 6) opens into a joint flap chamber (7) that transitions into a discharge channel (8) and in which a flap (9) is arranged, which is held with a holding section (10) in a reception compartment (11) of the pump casing (2) so that it can swivel and selectively closes one or the other pressure channel (5, 6), characterised in that the flap (9) being held floatingly without a shaft in the reception compartment (11) and the reception compartment (11) opening towards the flap chamber (7) via an opening (12) that is narrower than the holding section (10), wherein the holding section (11) is elastic in a way that it can be compressed to a width that is smaller than or equal to the width of the opening (12).

2. Dual pump assembly (1) according to claim 1, characterised in that the flap (9) being capable of swivelling around a moveable axis and a play existing on all sides around the holding section (10).

3. Dual pump assembly (1) according to claim 1 or 2, characterised in that the opening (12) being aligned with the discharge opening (13) of the discharge channel (8).

4. Dual pump assembly (1) according to one of the preceding claims, characterised in that the holding section (10) being made of an elastic material.

5. Dual pump assembly (1) according to one of the preceding claims, characterised in that the holding section (10) being formed by a hollow body, notably a hollow profile.

6. Dual pump assembly (1) according to one of the preceding claims, characterised in that the cross-section of the holding section (10) and the reception compartment (11) respectively being circular.

7. Dual pump assembly (1) according to one of the preceding claims, characterised in that the holding section (10) having play of at least 1 mm on all sides.

8. Dual pump assembly (1) according to one of the preceding claims, characterised in that the reception compartment (11) being approximately symmetrical and having a first and second side wing (21, 22), and the holding section (10) being formed so that, when closing the one pressure channel (5), it engages at least predominately in the second side wing (22) and, when closing the other pressure channel (6), it engages at least predominantly in the first side wing (21), in which the first pressure channel (5) and the second side wing (22) on the one hand as well as the other pressure channel (6) and the first side wing (21) on the other hand are located respectively on opposite sides of a symmetry axis (20) of the reception compartment (11).

9. Dual pump assembly (1) according to one of the preceding claims, characterised in that the holding section (10), viewed in cross-section, having a width (B) that is greater than its height (H).

10. Dual pump assembly (1) according to one of the preceding claims, characterised in that the wall of the reception compartment (11) being free of passages to the outside.

11. Dual pump assembly (1) according to one of the preceding claims, characterised in that the holding section (10) being formed integrally with a flap body (18) that closes one or the other pressure channel (5, 6), notably being fabricated in one piece with the same.

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