EP3913187A1 - Screw spindle pump - Google Patents

Abstract

Screw spindle pump, comprising a housing (3) with a barrel bore (14) consisting of at least two intersecting bores (15, 16), in each of which a spindle (4, 5) is accommodated, the spindles (4, 5) with one another in sections have intermeshing screw profiles (6, 7, 8, 9) and bend during operation by a hydraulic bending pressure in a defined bending direction (R), each bore (15, 16) like a slot with a longer first axis of symmetry (S1) and an orthogonal to it standing shorter second axis of symmetry (S2) is executed, wherein the longer first axis of symmetry (S1) runs in the bending direction (R).

Description

The invention relates to a screw spindle pump, comprising a housing with a barrel bore consisting of at least two intersecting bores, in each of which a spindle is received, the spindles having intermeshing screw profiles in sections and bending in a defined bending direction due to hydraulic bending pressure.

Such screw pumps are used to convey a wide variety of fluid media. They comprise a housing with a barrel bore which is formed by at least two intersecting bores. A spindle is received in each of these boreholes, one spindle usually being a drive spindle and the other being a running spindle driven by the other spindle. Sometimes two running spindles, which are arranged on both sides of a central engagement spindle, are also provided, in which case the running bore consists of three intersecting bores. The spindles have corresponding screw profiles by means of which they mesh with one another, with cavities being formed via the toothing engagement which form the conveying spaces for the fluid to be conveyed. This makes it possible to convey the fluid supplied on one side from this suction side to the pressure side, where the fluid is released. The structure and function of such a screw pump is basically known.

As described, the screw pump sucks in the fluid to be conveyed on the suction side and conveys it to the pressure side with constant compression. This results in a corresponding differential pressure between the suction and pressure sides, which, depending on the design of the screw pump, can range from a few bar to well over 100 bar. This means that, in particular the higher the differential pressure, a corresponding hydraulic bending pressure loads on the spindles, which, since the fluid path is defined within the pump, is always directed in a defined direction. This hydraulic bending pressure results in a bending of the spindles in a defined bending direction, i.e. that the spindles, which are usually mounted in plain bearings in the area of their two spindle ends, experience a slight deflection, that is to say are deformed. Since the spindles are arranged in the respective bores of the housing, which can either be a single housing or an insert that is inserted into an outer housing, and rotate in the corresponding bore, the relative position of the spindle changes accordingly to the bore wall, that is, the given ring segment-like gap increases slightly in width on one side due to the bending, while it becomes slightly narrower on the other side, whereby this change in width, of course, seen over the spindle length, varies slightly due to the bending geometry. In order to prevent the spindle or the screw profile from running against the inner wall of the bore as a result of this bending, which would be extremely wear-promoting, the bore diameter is selected with a corresponding oversize, so that ideally, despite the bending, there is still a corresponding distance even in the maximum bending area given is. In addition, it is known to arrange the spindle de-axisized in the central bore, that is to say to arrange its spindle axis slightly offset from the center against the bending direction. This design is made in such a way that, in the area of maximum bending, the distance between the spindle and the bore wall is almost the same in and opposite to the bending direction. This means that in this area there is a gap with an almost constant gap width between the spindle and the inner wall of the bore. The size of the gap surrounding all the spindles, which has the shape of an "8" in a running bore consisting of two bores, is included in the calculation of the delivery rate. This is because there is a certain amount of leakage through this gap, i.e. a certain amount of fluid that is not conveyed. The larger the gap or the circumferential gap cross-section, the greater this leakage portion.

The invention is thus based on the problem of specifying a screw pump which is improved in comparison.

To solve this problem, it is provided according to the invention in a screw pump of the type mentioned at the outset that each bore has an elongated hole a longer first axis of symmetry and a shorter, orthogonal to it, shorter second axis of symmetry, the longer first axis of symmetry running in the bending direction.

The screw pump according to the invention therefore has no centric, i.e. circular bores, as was previously the case in the prior art, but elongated bores, i.e. bores that do not have a clear radius, but are defined by two different, orthogonal axes of symmetry. The elongated hole has a first, longer axis of symmetry and a second, shorter axis of symmetry that is orthogonal thereto. The longer axis of symmetry runs in the bending direction, the shorter axis of symmetry runs orthogonally to it. This configuration has the advantage that, on the one hand, a deflection of the spindle is easily possible because, after the deflection takes place along the longer axis of symmetry, there is sufficient space within the bore to ensure that the spindle or its screw profile does not run against the inner wall of the bore . In the orthogonal direction, however, in which there is no deformation, it is possible due to the elongated design to reduce the distance between the opposing wall surfaces of the bore, so that overall a smaller gap width results in the direction of the second axis of symmetry than in the direction of the first Axis of symmetry. Due to this slot-like bore geometry, the entire cross-sectional area of the gap can be reduced considerably, since due to the slot-like design with a longer and shorter axis of symmetry, there is no round gap surrounding the respective spindle with a constant width around the circumference, but a gap with a gap width that varies around the circumference . Depending on how close the opposite bore inner wall areas move to the spindle in the short axis of symmetry, there is a correspondingly strong reduction in the gap width, which in turn is reflected in a correspondingly large reduction in the overall gap cross-section.

The reduction of this gap cross-section therefore inevitably also results in a considerable reduction in the leakage volume over the range of the differential pressure interval, tests having shown that a reduction of up to 25% or more is easily possible.

The screw spindle pump according to the invention or the bore geometry provided according to the invention thus enables problem-free and low-wear pump operation on the one hand, since a spindle bending resulting from the hydraulic bending pressure is possible without problems and there is always a sufficient distance to the adjacent bore walls in the direction of the longer axis of symmetry, as well as at the same time due to The reduced gap diameter in the direction of the shorter axis of symmetry results in a considerable reduction in the entire gap cross-section and thus in the leakage volume. This results on the one hand in extremely low-wear sales and, on the other hand, in a significantly more efficient production operation compared to the previous circular bore geometry.

In order to enable the distance between the spindle and the screw profile in the direction of the first longer axis of symmetry to be almost the same on both sides in the direction of the first, longer axis of symmetry, it is advisable to use the spindles or their spindle axes in the unloaded state to be arranged offset to the center of the first axis of symmetry, i.e. also to be positioned quasi eccentrically here. As stated, the location of the same distance ultimately relates to the area of the greatest spindle deflection, this area usually being in the central spindle area.

The arrangement is expediently such that the spindles are positioned so that at a defined differential pressure between a suction side and a pressure side of the pump or within a defined differential pressure interval, the width of the gap between the screw profiles and the inner wall of the bore in the direction of the first axis of symmetry is greater than is the width of the gap in the direction of the second axis of symmetry. It means that the arrangement of the spindles is such that, in the event of bending, the distance between the screw profile and the inner wall of the bore in the direction of the first axis of symmetry in both axial directions is always greater than the distance or the gap width in the orthogonal second axis of symmetry. In the direction of the second axis of symmetry, the gap is consequently always narrower in operation than in the direction of the first axis of symmetry. In this way, symmetrical relationships in the direction of both axes of symmetry can ultimately be set in this bending area.

As described, each hole is designed as a slot-like hole with two different lengths of orthogonal axes of symmetry. Such a bore can be formed, for example, by means of a milling tool which makes it possible not only to introduce a cylindrical bore, but also to lengthen it slightly in the direction of the first axis of symmetry to form a slot-like shape. There is also the alternative possibility of lengthening the bore like a slot by grinding a cylindrical bore. A simple cylindrical bore is first made, which is then ground out in a defined manner to form the longer axis of symmetry. In contrast, a further alternative possibility of forming a bore provides that each bore is formed from two separate, intersecting individual bores, the bore axes of which are offset from one another in the bending direction. Each hole therefore consists of two individual holes that intersect with one another. These are minimally offset from one another in the bending direction, that is, their bore axes are minimally spaced in the bending direction, namely by the distance of the expected maximum deflection, which is in the range of 0.1-0.3 mm, for example. The formation of the bore using two separate individual bores has the advantage, on the one hand, that the bore as such can be easily introduced, since the formation of the bores only requires a simple linear movement of the drilling tool. In addition, a drilling tool can be used that has a smaller diameter than a drilling tool that is used to produce a circular, central bore, as has been customary in the prior art up to now (this also applies to the use of a milling cutter, this can also be selected with a smaller diameter). All that needs to be ensured is that the diameter of the two individual bores is sufficiently large that the spindle, viewed in the direction of the second axis of symmetry, is still sufficient, although it is spaced from the wall of the bore via a significantly narrower gap, after there is sufficient space for in the direction of the first axis of symmetry the bend is taken up. When two intersecting individual bores are formed, a minimal web or shoulder, which extends only a few micrometers inward into the bore due to the geometry, remains in the cutting area, i.e. in the direction of the second axis of symmetry, due to the geometry. Although this narrows the gap marginally, its height is so small that it in no case has a detrimental effect on the spindle movement in and against the bending direction, especially since there is no spindle deformation anyway in the direction of the second axis of symmetry.

The two individual bores expediently extend over the entire length of the housing, which simplifies their formation. As described, the housing can be a complete housing or a central housing block that is only closed by two covers. Alternatively, the housing can also be an insert that is inserted into a corresponding outer housing.

As an alternative to the configuration in which the two individual bores of each bore extend over the entire length of the housing, it may also be possible, according to a variant of the invention, that each bore consists of two axially adjoining bore sections, the central axes of each bore section being set against one another. In this embodiment of the invention, each bore is consequently composed of two separate bore sections, each bore section in turn being formed from two separate individual bores as described above. The bore sections naturally merge into one another, but are not in an axial arrangement or are not axially aligned with one another, but are marginally angled to one another. The employment is chosen in such a way that this approximates the bending geometry of the spindle. This means that each bore section, which begins on one side of the housing and runs towards the center of the housing, runs minimally at an angle, so that, viewed in cross-section, there is virtually a minimal V-shape, with the tip of the V pointing in the bending direction. This bore geometry therefore takes on the spindle bending geometry, so that the bore geometry adapts even better to the actual conditions and in particular the gap resulting from the elongated hole-like shape and adapted to the bend is even better adapted to the spindle bend, seen in the axial direction.

The screw pump is preferably a double-flow pump, that is, each screw spindle has two axially adjacent screw profiles rising in opposite directions, which are preferably provided approximately in the region of the longitudinal center of the respective screw spindles or approximately symmetrically to the longitudinal center. In this double-flow pump form, corresponding, oppositely running screw profiles are provided which extend from the area of the spindle center in the direction of the spindle ends where the spindle is mounted. Alternatively, it can also be a single-flow pump in which each spindle only has a screw profile that increases in one direction.

The screw pump itself is either a pure liquid pump. Alternatively, however, it can also be a multiphase pump which, in addition to a pure liquid, can also convey a liquid-gas mixture.

In addition to the screw pump itself, the invention also relates to a housing for a screw pump of the type described. The housing has a barrel bore consisting of at least two intersecting bores for receiving one spindle each, the spindles having intermeshing screw profiles in sections and during operation of the Bend the screw pump in a defined bending direction using hydraulic bending pressure. This housing, which can be the actual pump housing, or an insert in one Outer housing is characterized according to the invention in that each bore is designed like a slot with a longer first axis of symmetry and a shorter, second axis of symmetry orthogonally to it, the longer first axis of symmetry running in the bending direction.

In this case, each bore is preferably formed from two separate, intersecting individual bores, the bore axes of which are offset from one another in the bending direction. Alternatively, the elongated hole can also be designed as a milled hole, i.e. the milling tool is guided accordingly to lengthen the hole while forming the longer axis of symmetry. Another alternative provides that the slot-like bore is ground from a cylindrical bore, i.e. that material is specifically removed locally by grinding in order to form the longer axis of symmetry.

Each of the two individual bores can extend over the entire length of the housing, that is to say that the entire bore consists of these two axially extending individual bores. As an alternative to this, it is conceivable that each bore consists of two axially adjoining bore sections, the central axes of each bore section and thus the central axes of the individual bores of a bore section being set against one another with respect to those of the other bore section. Here, each bore section is thus formed from two separate individual bores, the bore axes of which are slightly adjusted to one another, that is to say they assume an angle not equal to 180 ° to one another and are not aligned with one another. This makes it possible to tilt the entire bore geometry minimally following the bending line.

The invention further relates to a method for producing a housing for a screw pump of the type described above, comprising a barrel bore formed from at least two intersecting bores. This method is characterized in that, in order to form each bore, at least two separate, intersecting individual bores, the bore axes of which are offset from one another, in one Housing body to be drilled. The two individual bores or their bore axes are offset from one another in a previously defined bending direction.

Furthermore, it can be provided that the individual bores extend over the entire length of the housing body. Alternatively, each bore can also consist of two axially adjoining bore sections, the central axes of each bore section being positioned against one another, with two separate individual bores being drilled on each of the two opposite sides of the housing body to form the bore sections. The bore sections or the individual bores meet in the center of the housing, where the area of the maximum spindle bending is.

Fig. 1

eine Perspektivansicht einer erfindungsgemäßen Schraubenspindelpumpe im teilweise aufgeschnittenen Zustand,

Fig. 2

das ausgeschnittene innere Gehäuse nebst zweier Spindeln der Schraubenspindelpumpe aus Fig. 1,

Fig. 3

eine Stirnseitenansicht des Gehäuses aus Fig. 2 unter Darstellung der Laufbohrung,

Fig. 4

eine Prinzipdarstellung zur Ausbildung der beiden die Laufbohrung bildenden Bohrungen, jeweils bestehend aus zwei einander schneidenden Einzelbohrungen,

Fig. 5

eine Prinzipdarstellung einer langlochartigen Bohrung nebst deachsiert darin angeordneter Spindel im unbelasteten Zustand,

Fig. 6

die Anordnung aus Fig. 5 mit belasteter Spindel,

Fig. 7

eine Prinzipdarstellung einer zentrischen Bohrung mit deachsiert angeordneter Spindel gemäß Stand der Technik,

Fig. 8

die Anordnung aus Fig. 7 mit belasteter Spindel, und

Fig. 9

eine Prinzipdarstellung einer Schraubenspindelpumpe respektive eines Gehäuses mit zwei unter einem Winkel zueinander angestellten Bohrungabschnitten.

Further advantages and details of the present invention emerge from the exemplary embodiments described below and on the basis of the drawings. Show:

Fig. 1

a perspective view of a screw pump according to the invention in a partially cut-open state,

Fig. 2

the cut out inner housing together with two spindles of the screw pump Fig. 1 ,

Fig. 3

an end view of the housing Fig. 2 showing the barrel bore,

Fig. 4

a schematic representation of the formation of the two bores forming the barrel bore, each consisting of two individual bores intersecting one another,

Fig. 5

a schematic representation of a long hole-like bore along with the axially aligned spindle in the unloaded state,

Fig. 6

the arrangement Fig. 5 with loaded spindle,

Fig. 7

a schematic representation of a central bore with an axially arranged spindle according to the prior art,

Fig. 8

the arrangement Fig. 7 with loaded spindle, and

Fig. 9

a schematic representation of a screw pump or a housing with two borehole sections positioned at an angle to one another.

Fig. 1 shows, in the form of a partially cut-away perspective view, a double-entry screw pump 1 according to the invention, comprising an outer housing 2 with an inner housing 3 designed as an insert, in which, see Fig. 2 , two spindles 4, 5 are arranged, which are used to suck in, convey and dispense a fluid or a liquid-gas mixture. For this purpose, an inlet is provided on the housing side, as shown by the arrow P1, through which the fluid is sucked in. The fluid is released under pressure via an outlet (not shown in greater detail), which is arranged at 90 degrees in the example shown, as shown by the arrow P2.

The two spindles 4, 5 each have two screw profiles 6, 7 and 8, 9, the respective screw profile pairs 6, 7 and 8, 9 having opposing slopes. This means that it is a double-entry screw pump 1. The screw profiles 6 and 8 would come together in a manner known per se, as would the screw profiles 7 and 9.

The two screw spindles 4, 5 are supported and rotatably supported in the region of their respective ends via corresponding bearing means 10, 11 and 12, 13, the bearing means 10-13 generally being slide bearings.

The two spindles 4, 5 are received in a barrel bore 14, which has the shape of a "lying 8" and which is shown as a schematic diagram in FIG Fig. 3 shown is. Fig. 3 shows an end view of the housing 3 with a view of the barrel bore 14, which extends axially in a straight line through the housing 3.

The barrel bore 14 consists of two separate bores 15, 16 which intersect one another so that two central shoulders 17 result. A spindle 4, 5 is received in each bore 15, 16 and rotates therein, one spindle being the drive spindle coupled to a drive motor, while the other spindle is the running spindle. In the example shown, the spindle 5 is the drive spindle, while the spindle 4 is the following running spindle. The spindles 4, 5 are received in the running bore 14 or the bores 15, 16 at a distance from the adjacent inner wall of the bore, so that they can rotate without contact. As a result, a gap is formed which runs around both spindles 4, 5 and which also has the shape of a "lying 8".

According to the invention, each of the bores 15, 16 is designed in the manner of a slot, that is to say that each bore 15, 16 is not a circular bore, but rather has a longer and a shorter axis of symmetry. Of course, the two bores 15, 16 intersect, but each bore has to be assigned a defined, specific elongated hole geometry.

Fig. 4 shows a schematic diagram in this regard. The two bores 15, 16 are shown. Each bore 15, 16 consists of two intersecting individual bores 18, 19 in the case of the bore 15 and 20, 21 in the case of the bore 16. The two pairs of individual bores 18, 19 and 20, 21 respectively have Bore or central axes Z1 and Z2, which, however, are spaced from one another in a bending direction R here. This bending direction R is the direction in which the respective spindle 4, 5 bends due to the hydraulic bending pressure given in the housing 3, resulting from the pressure difference between the suction side and the pressure side. This bending is minimal, but it is a result of the quasi end-side support of the spindles 4, 5 via the bearing means 10-13. This defined bending deformation occurring in the bending direction R now leads to the screw profiles 6, 7, 8, 9 their position relative to the inner wall of the bore compared to the unloaded one State, change slightly so that, as will be discussed below, the corresponding gap surrounding the respective spindle 4, 5 or the respective screw profile 6-9 varies in width.

In Fig. 4 the respective individual bores 18, 19 or 20, 21, for reasons of clarity alone, are clearly spaced from one another by the distance a with their central axes Z1. In fact, the distance a is, for example, only 0.1-0.3 mm, so it is minimal, but nevertheless measurable.

This offset of the individual bores 18, 19 in the bending direction R now means that the resulting bore 15, 16 has a slot-like geometry, i.e. no longer a circular bore shape or inner wall shape, but a slightly elongated bore shape. Each individual bore 15, 16 therefore has a longer first axis of symmetry S1, which extends in the bending direction R, and a second, shorter axis of symmetry S2 that is orthogonal thereto. The axes of symmetry S1, S2 are shown for the bore 15; the geometry of the bore 16 is identical. The difference in length between the axes of symmetry S1 and S2 ultimately corresponds to the distance a between the two central axes Z1, Z2, and is therefore also approximately 0.1-0.3 mm.

As described, it is Fig. 4 a pure principle illustration with respective individual bores 18, 19 and 20, 21, which are spaced apart from one another in an exaggerated manner. The result is in Fig. 4 a shoulder on the right-hand side of the bore 15 or on the left-hand side of the bore 16. However, this is actually only marginally pronounced with the given minimum axial offset a, it has a height of a few micrometers and consequently does not hinder the spindle movement or bending and also has no influence on the pump operation.

The mode of operation of this elongated hole-like configuration of the bores 15, 16 in comparison to a purely centric one that has hitherto been customary in the prior art Hole is based on the Fig. 5 and 6th compared to the Figures 7 and 8 clear. the Fig. 5 shows in the form of a schematic representation of a slot-like bore 15, which is shown here closed for descriptive and illustrative reasons (the following description, which explains the basic principle, of course also applies to the second slot-like bore 16, which is 8-shaped with the bore 15 Barrel bore 14 supplemented). The spindle 4 or the outer circumference of the screw profile 6 is also shown as a schematic diagram Fig. 5 shows, between the inner wall 22 of the slot-like bore 15 and the outer circumference 23 of the screw profile 6, in the example shown, a ring-shaped circumferential gap space 24, in which the fluid collects during operation for conveying (the running bore is that of the respective bore 15, 16 The gap to be assigned only like a ring segment, the two ring segments complementing each other to form an "8" shape). The longer first axis of symmetry S1 and the shorter, second axis of symmetry S2 are also shown. Also shown is the diameter D of the spindle 4 and its longitudinal or central axis ZS. This can be seen at a distance b from the longitudinal center or the central axis Z of the bore 15, namely against the bending direction R. That means that it, seen in Fig. 5 , is offset slightly upwards from the center of the bore 15. The distance dimension b ultimately corresponds to the distance dimension a by which the two individual bores 18, 19 are offset, via which the bore 15 is formed.

If, during operation, a hydraulic bending pressure acts on the spindle 4 in the direction of the bending direction R, it bends slightly. Fig. 6 shows this operating situation, the area of the maximum spindle deflection being shown here. It can be seen that the central axis ZS of the spindle 4 and the central axis Z of the bore 15 coincide by way of example. The spindle 4 thus bends slightly downwards in the bore 15. This leads to the fact that the width B1 of the here annular gap or gap space 24, seen in the direction of the first, longer axis of symmetry S1 and thus in the bending direction R, is almost the same compared to the unloaded state. Viewed in the direction of the second, shorter axis of symmetry S2, however, the width B2 of the gap space 24 is significantly narrower. The gap width consequently changes around the circumference or constricts from the upper and lower axis point on the first axis of symmetry S1 to the lateral axis points on the second axis of symmetry S2, which is also given in the case of a barrel bore. This results from the fact that the two individual bores 18, 19 each have a bore diameter d1 and d2 that is somewhat smaller than the diameter that a purely central bore would have. Such a central bore 25, as would be provided in the prior art, is shown in FIG Fig. 6 shown in dashed lines. Obviously, the diameter of such a central bore would correspond to the length of the longer first axis of symmetry S1. Viewed in the direction of the shorter, second axis of symmetry S2, the comparison in FIG Fig. 6 It is clear that the width B2 of the gap 24 is significantly smaller compared to the situation in the case of a central bore 25. This shows how Fig. 6 also clearly shows that the total cross-sectional area of the gap space 24 with the design of an elongated hole 15 compared to the cross-sectional area with the formation of a central hole 25 is significantly smaller, which in turn means that any leakage volume can be significantly reduced and consequently the delivery volume as well as the Efficiency of the screw pump can be improved.

the Figures 7 and 8 show, for comparison, the arrangement of the spindle 4 in a central bore 25, that is to say a bore with a constant diameter which corresponds to the length of the first axis of symmetry S1. Here, too, the central axis ZS of the spindle 4 is de-axisized to the central axis Z of the circular central bore 25;

If the spindle 4 is now loaded during operation, it bends slightly, as in FIG Fig. 8 is shown. As can be seen, the spindle 4 is then quasi-centric in the central bore 25. This results in an annular circumferential gap space 24 which has almost the same width B1 around the entire circumference, i.e. the gap width as it is only in the upper and lower areas in the embodiment according to the invention Axis point is given. It can be seen in Fig. 8 resulting Cross-sectional area of the annular gap space 24 is significantly larger than the area of the gap space 24 according to FIG Fig. 6 .

The inventive reduction of the gap area or the distance between the inner wall of the bore and the spindle, seen in the plane of the shorter, second axis of symmetry S2, results from the slot-like configuration and the fact that it offers the possibility of producing the respective bore from two individual bores whose respective individual diameter d1 , d2 is smaller than the diameter d of a cylindrical bore, which would be equally suitable to accommodate the spindle bending. That is, d1, d2 <d.

Although it has been described above that the respective bore 15, 16 is formed via two individual bores 18, 19 or 20, 21, which are introduced one after the other and intersect, there is basically also the possibility of opening the respective bore 15, 16 by means of a milling cutter to form, which on the one hand introduces a hole, but on the other hand can also be moved slightly in the bending direction in order to produce the elongated hole geometry. This also has a diameter which is smaller than the diameter of a drill which forms a central bore as is customary in the prior art.

In the exemplary embodiment of the figures described above, each bore 15, 16 extends linearly through the housing 3 angled configuration of the bore sections to accommodate the shape of the resulting spindle bend. A schematic representation of such an arrangement is in Fig. 9 shown. The housing 3 and the bore 15 are shown there by way of example. This consists of two bore sections 15a, 15b, each bore section in turn consisting of two separate, mutually intersecting individual bores 18a, 19a or 18b, 19b that intersect, as above for the first Alternative invention described. That means that too here the individual bores 18a, 19a or 18b, 19b are minimally offset by the distance a in the bending direction. It can be seen that the bore sections 15a, 15b are not aligned with one another, but are at an angle α ≠ 180 ° to one another, that is to say they are tilted or set in the middle in the bending direction R, as it were.

the Fig. 9 also shows schematically the course of the central axis ZS of the spindle 4, which is inevitably also slightly bent due to the spindle bending. The angled inclination of the bore sections 15a 15b now approximately takes up this bending line or curved axis course, so that ultimately the overall resulting, quasi-angled or kinked bore 15 is better adapted to the spindle geometry resulting from hydraulic loading.

Here too, of course, the bend and angled inclination are clearly exaggerated, purely for reasons of illustration. In fact, the angle α is only a few minutes.

Although the described exemplary embodiments, in particular the Figs. 1-4 , shows a double-entry screw pump with two spindles, the invention is of course not limited to this. Rather, it can also be a single-flow screw spindle pump, where only one screw profile is provided on each spindle. In addition, more than two spindles can also be provided, which means that a central work spindle and two parallel running spindles are provided. In principle, the elongated hole-like configuration of the respective spindle bore according to the invention can be used wherever spindle bending is given and compensated for during operation due to the given hydraulic pressure conditions.

Claims (15)

Screw spindle pump, comprising a housing (3) with a barrel bore (14) consisting of at least two intersecting bores (15, 16), in each of which a spindle (4, 5) is accommodated, the spindles (4, 5) with one another in sections have intermeshing screw profiles (6, 7, 8, 9) and bend during operation by a hydraulic bending pressure in a defined bending direction (R), characterized in that each bore (15, 16) is elongated with a longer first axis of symmetry (S1) and a shorter second axis of symmetry (S2) which is orthogonal thereto, the longer first axis of symmetry (S1) running in the bending direction (R). Screw spindle pump according to Claim 1, characterized in that the spindles (4, 5) are arranged offset from the center (Z) of the first axis of symmetry S (1) in the unloaded state. Screw spindle pump according to claim 2, characterized in that the spindles (4, 5) are positioned such that at a defined differential pressure between a suction side and a pressure side of the pump or within a defined differential pressure interval, the width (B1) of a gap (24) between the screw profiles (6, 7, 8, 9) and the inner wall of the bore (22) in the direction of the first axis of symmetry (S1) is greater than the width (B2) of the gap (24) in the direction of the second axis of symmetry (S2). Screw spindle pump according to one of the preceding claims, characterized in that each bore (15, 16) consists of two separate, intersecting individual bores (18, 19, 20, 21), the bore axes (Z1, Z2) of which are offset from one another in the bending direction (R) , or is formed as a milled bore or as a bore ground from a cylindrical bore. Screw spindle pump according to one of the preceding claims, characterized in that the two individual bores (18, 19, 20, 21) extend over the entire length of the housing (3). Screw pump according to one of Claims 1 to 4, characterized in that each bore (15, 16) consists of two axially adjoining bore sections (15a, 15b), the central axes of each bore section (15a, 15b) being set against one another. Screw spindle pump according to one of the preceding claims, characterized in that each spindle (4, 5) has two axially adjacent, oppositely rising screw profiles (6, 7, 8, 9) which are provided in the area of the longitudinal center of the respective spindles (4, 5) , having. Screw spindle pump according to one of the preceding claims, characterized in that it is a liquid pump or a multiphase pump. Housing for a screw spindle pump (1) according to one of the preceding claims, with a running bore (14) consisting of at least two intersecting bores (15, 16) for receiving one spindle (4, 5) each, the spindles (4, 5) have mutually intermeshing screw profiles (6, 7, 8, 9) in sections and bend during operation of the screw pump (1) by a hydraulic bending pressure in a defined bending direction (R), characterized in that each bore (15, 16) is elongated with a longer first axis of symmetry (S1) and a shorter second axis of symmetry (S2) orthogonal thereto, the longer first axis of symmetry (S1) running in the bending direction (R). Housing according to claim 9, characterized in that each bore (15, 16) consists of two separate, intersecting individual bores (18, 19, 20, 21), the bore axes (Z1, Z2) of which are offset from one another in the bending direction (R), or as a milled bore which is formed as a bore ground from a cylindrical bore. Housing according to Claim 9 or 10, characterized in that the two individual bores (18, 19, 20, 21) extend over the entire length of the housing (3). Housing according to claim 9 or 10, characterized in that each bore (15, 16) consists of two axially adjoining bore sections (15a, 15b), the central axes of each bore section (15a, 15b) being set against one another. Method for producing a housing for a screw spindle pump according to one of Claims 1 to 8, comprising a barrel bore (14) formed from two intersecting bores (15, 16), characterized in that either at least two separate, intersecting individual bores (18, 19, 20, 21), the bore axes (Z1, Z2) of which are offset from one another, are drilled into a housing body, or each bore is milled with the two different axes of symmetry, or each bore is milled by grinding a cylindrical one Bore is formed with the two different axes of symmetry. Method according to Claim 13, characterized in that the two individual bores (18, 19, 20, 21) extend over the entire length of the housing body. Method according to claim 13, characterized in that each bore consists of two axially adjoining bore sections (15a, 15b), the central axes of each bore section (15a, 15b) being set against one another, with the formation of the bore sections (15a, 15b) on both opposing each other Two separate individual bores (18a, 19a, 18b, 19b) are drilled on each side of the housing body.

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