Screw pump

Abstract

A screw spindle pump for the delivery of fluid media with a pump housing having an inlet channel with a first longitudinal axis, an outlet channel with a second longitudinal axis, a first drive spindle with a third longitudinal axis, and a second driven spindle. The spindles each include a profiled section between the inlet channel and the outlet channel, wherein the profiled sections of the spindles are engaged at least partially with one another and form, with the pump housing between the inlet channel and the outlet channel, a delivery section parallel to the longitudinal axis of the drive spindle with delivery chambers for the fluid medium. The second longitudinal axis of the outlet channel is disposed at an obtuse angle to the delivery section in the pump housing. The invention also relates to a method for operating a screw spindle pump.

Claims

1. A screw spindle pump for the delivery of fluid media with a pump housing, comprising: at least one inlet channel with a first longitudinal axis; at least one outlet channel with a second longitudinal axis; a drive spindle with a third longitudinal axis; and at least one driven spindle; wherein the drive spindle and at least one driven spindle are disposed at least section-wise in the pump housing, the drive spindle and at least one driven spindle each comprise a profiled section between the at least one inlet channel and the at least one outlet channel, wherein the profiled sections of the drive spindle and at least one driven spindle are engaged at least partially with one another and form, with the pump housing between the at least one inlet channel and the at least one outlet channel, a delivery section parallel to the third longitudinal axis of the drive spindle with delivery chambers for the fluid medium; wherein the second longitudinal axis of the at least one outlet channel is disposed at an obtuse angle to the delivery section in the pump housing; and wherein the drive spindle comprises a profiled section and a shank section, the drive spindle in a section adjacent to the outlet channel is constituted as an at least section-wise concavely rounded conically shaped section, and the at least section-wise concavely rounded conically shaped section is a partial section of the shank section and is adjacent to the profiled section.

2. A screw spindle pump for the delivery of fluid media with a pump housing, comprising: at least one inlet channel with a first longitudinal axis; at least one outlet channel with a second longitudinal axis; a drive spindle with a third longitudinal axis; and at least one driven spindle; wherein the drive spindle and at least one driven spindle are disposed at least section-wise in the pump housing, the drive spindle and at least one driven spindle each comprise a profiled section between the at least one inlet channel and the at least one outlet channel, wherein the profiled sections of the drive spindle and at least one driven spindle are engaged at least partially with one another and form, with the pump housing between the at least one inlet channel and the at least one outlet channel, a delivery section parallel to the third longitudinal axis of the drive spindle with delivery chambers for the fluid medium; wherein the second longitudinal axis of the at least one outlet channel is disposed at an obtuse angle to the delivery section in the pump housing; wherein the drive spindle is constituted at least section-wise as a concavely rounded conically shaped section; and wherein the concavely rounded conically shaped section tapers in the direction of the profiled section.

3. The screw spindle pump of claim 1, wherein the fluid medium can be conveyed via the concavely rounded conically shaped section into a second flow direction (SR2), wherein the second flow direction forms with the delivery section an angle that is not equal to 90.

4. The screw spindle pump of claim 3, wherein the second flow direction forms with the delivery section an angle that is greater than 90.

5. The screw spindle pump of claim 1, wherein an eddy formation of the delivered medium is reduced in a region of the at least one outlet channel of the screw spindle pump.

6. The screw spindle pump of claim 1, wherein at least a second driven spindle is disposed completely inside the pump housing.

7. A screw spindle pump for the delivery of fluid media with a pump housing, comprising: at least one inlet channel with a first longitudinal axis; at least one outlet channel with a second longitudinal axis; a drive spindle with a third longitudinal axis; and at least one driven spindle; wherein the drive spindle and at least one driven spindle are disposed at least section-wise in the pump housing, the drive spindle and at least one driven spindle each comprise a profiled section between the at least one inlet channel and the at least one outlet channel, wherein the profiled sections of the drive spindle and at least one driven spindle are engaged at least partially with one another and form, with the pump housing between the at least one inlet channel and the at least one outlet channel, a delivery section parallel to the third longitudinal axis of the drive spindle with delivery chambers for the fluid medium; wherein the second longitudinal axis of the at least one outlet channel is disposed at an obtuse angle to the delivery section in the pump housing; and wherein the screw spindle pump has three spindles, with a drive spindle and two female screw spindles, wherein the longitudinal axes of the three spindles are disposed in parallel and in a plane, wherein the longitudinal axis of the drive spindle is disposed centrally between the longitudinal axes of the female screw spindles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Examples of embodiment of the invention and its advantages are explained in greater detail below with the aid of the appended figures. The size ratios of the individual elements with respect to one another in the figures do not always correspond to the actual size ratios, since some forms are represented simplified and other forms magnified compared to other elements for the sake of better clarity.

(2) FIGS. 1A-1B show a screw spindle pump according to the invention.

(3) FIGS. 2A-2B show a drive spindle with a modification according to the invention.

(4) FIGS. 3A-3B each show a cross-section through the outlet region of a screw spindle pump.

(5) FIGS. 4A-4B show diagrammatically the arrangements of various longitudinal axes in the pump housing.

(6) FIG. 5 shows a further representation of a partial region of a screw spindle pump.

DETAILED DESCRIPTION OF THE INVENTION

(7) Identical reference numbers are used for identical or identically acting elements of the invention. Furthermore, for the sake of clarity, only reference numbers that are required for the description of the given figure are represented in the individual figures. The represented embodiments only represent examples as to how the device according to the invention or the method according to the invention can be constituted and do not represent a conclusive limitation.

(8) FIGS. 1A and 1B show a screw spindle pump 1 according to the invention with pump housing 2. A drive spindle 5, a first female screw spindle 6 and a second female screw spindle 6* (scarcely visible, see FIG. 5) are disposed in said pump housing. In particular, second female screw spindle 6* is disposed, proceeding from rotational axis D of drive spindle 5, at an angle of 180 to first female screw spindle 6 in pump housing 2, i.e. the longitudinal axes or rotational axes of the three spindles 5, 6, 6* lie in a plane. The delivered medium flows in flow direction SR1 through inlet channel 7 along a first longitudinal axis L1 into pump housing 2. In inlet region 8, the delivered medium is deflected and is now transported in delivery direction FR parallel to rotational axis D or longitudinal axis L3 of drive spindle 5 through pump housing 2. In the described example of embodiment, rotational axis D corresponds to longitudinal axis L3 of drive spindle 5. The medium then leaves pump housing 2 via outlet channel 9 along a second longitudinal axis L2. The delivered medium is thus transported in the axial direction from the suction side to the pressure side.

(9) Drive spindle 5 is hydraulically mounted in pump housing 2 over the entire length of the turns, i.e. in its entire profiled section P (see FIG. 2). Pump housing 2 comprises an accommodation housing 22 for a shaft seal 20 and a ball bearing 26 of drive spindle 5, from which a shaft section A exits section-wise through an opening 15 from pump housing 2. Sealing elements 21 are disposed on drive spindle 5 as shaft seal 20 in accommodation housing 22 in order to seal pump housing 2 in the region of shaft exit opening 15. In a shaft section A adjacent to profiled section P, drive spindle 5 is again mounted mechanically by means of ball bearing 26 in a zone of low pressure. Shaft seal 20 takes place in particular by means of sealing elements 21, which enable a rotation of drive spindle 5 relative to pump housing 2, for example slide ring seals, shaft sealing rings or stuffing box packings. A further sealing system is assigned to shaft section AD of the shaft shank of drive spindle 5 with an enlarged diameter (see FIG. 2) as a labyrinth seal 28. The latter is capable of reducing the pressure from the high-pressure side to the low-pressure side. The gap flow thus arising prevents jamming of drive spindle 5 in pump housing 2 and at the same time lubricates ball bearing 26. Furthermore, widened section AD of the shaft shank of drive spindle 5 designed as a hydraulically operating compensating piston 28 reduces the axial bearing forces, in that the forces acting on the screw profile are roughly balanced out hydraulically with those of the compensatory piston.

(10) The continuous leakage flow exiting towards the low-pressure side is responsible for the heat exchange and the lubrication of sealing elements 21 of shaft seal 20, for example of the slide ring seals. The leakage flow is carried away via a channel to the suction side and thus prevents a gradual pressure increase in the sealing space.

(11) The hollow spaces that are formed by pump housing 2, drive spindle 5 and female screw spindles 6, 6* form the delivery spaces for the delivered medium. When screw spindles 5, 6, 6* rotate, the delivery spaces move in delivery direction FR and thus deliver the medium from the suction side (=inlet channel) to the pressure side (=outlet channel).

(12) The delivered medium flows through inlet channel 7 largely orthogonal to the longitudinal axis of spindles 5, 6, 6* into pump housing 2 and is deflected in inlet region 8. The delivered medium is then moved by the motion of screw spindles 5, 6, 6* in the delivery spaces formed inside the pump housing in the direction of drive M. Delivery direction FR is largely parallel to longitudinal axis L3 of drive spindle 5. The delivered medium is then again deflected and leaves pump housing 2, whereby it flows out through an outlet channel 9. The section through which the medium has passed inside the pump housing is also referred to as delivery section FS.

(13) Longitudinal axis L2 of outlet channel 9 in pump housing 2 is preferably disposed at an angle not equal to 90 with respect to longitudinal axis L3 of drive spindle 5. In particular, outlet channel 9 is constituted inclined in such a way that an obtuse angle is formed between profiled section P of drive spindle 5 and longitudinal axis L2 of outlet channel 9. The medium leaves pump housing 2 through outlet channel 9 in a second flow direction SR2. This second flow direction SR2 or second longitudinal axis L2 of outlet channel 9 forms an obtuse angle with delivery section FS. Since longitudinal axis L1 of inlet channel 7 is preferably disposed orthogonal to longitudinal axis L3 of drive spindle 5, it emerges that first longitudinal axis L1 of inlet channel 7 and second longitudinal axis L2 of outlet channel 9 are disposed in a common plane at an angle to one another. Alternatively, provision can also be made such that first longitudinal axis L1 of inlet channel 7 and third longitudinal axis L3 of drive spindle 5 define a first plane and that second longitudinal axis L2 of outlet channel 9 is not disposed in this plane. In particular, in this alternative embodiment, second longitudinal axis L2 of outlet channel 9 is disposed in another plane and at an angle with respect to first longitudinal axis L1 of the inlet channel. In conventional pumps, on the other hand, the flow direction of the delivered medium in the region of inlet channel 7 is usually largely parallel to the flow direction of the delivered medium in the region of outlet channel 9, and the flow direction of the delivered medium in the region of the outlet channel is largely orthogonal to delivery direction FR along the longitudinal axis of the drive spindle inside the pump housing.

(14) FIGS. 2A and 2B show a drive spindle 5 with a modification according to the invention. The latter comprises a profiled section P with a formed spindle profile or with a helical profile, which together with the profiled sections of female screw spindles 6, 6* (see FIGS. 1A and 1B) form the delivery chambers for the medium to be delivered. Furthermore, drive spindle 5 comprises a shank section S. The latter comprises a shaft section A with bearing section AL. In ready-assembled screw spindle pump 1, bearing section AL is mounted rotatably in ball bearing 26 of accommodation housing 22 constituted as shaft exit opening 15 and part of pump housing 2 (see FIGS. 1A and 1B). Disposed between axial section A and profiled section P is a conically shaped section K. The conically shaped section K is located inside pump housing 2 in the region of outlet channel 9 in the assembled screw spindle pump 1. The diameter of conically shaped section K tapers against delivery direction FR of the medium inside pump housing 2. In particular, conically shaped section K is constituted as a concavely rounded cone. Additionally, conically shaped section K on drive spindle 5 generates a swirl of the delivered medium and leads to better introduction of the delivered medium at the stator or into outlet channel 9 (see FIGS. 1A and 1B).

(15) On account of the structurally differently selected shape and position of outlet channel 9, in particular on account of the inclined position of outlet channel 9, there is a less marked deflection of the delivered medium between delivery direction FR and second flow direction SR2 in the region of outlet channel 9. This, in combination with concavely rounded conically shaped section K, produces an advantageous flow of the delivered medium in the region of outlet channel 9. In particular, the eddy formation is reduced and the flow is therefore less turbulent. An improvement in the hydraulic efficiency of screw spindle pump 1 is thus achieved.

(16) Concavely rounded conically shaped section K also performs the additional function of preventing an axial displacement of female screw spindles 6, 6* (see FIGS. 1A and 1B) including their bearing bushes.

(17) FIG. 2 B shows a detail region of drive spindle 5. In particular, conically shaped section K tapers at least section-wise concavely (see reference symbol kV) in the direction of profiled section P. This brings about the advantageous deflection of the flow of the delivered medium laterally into inclined outlet channel 9 (see FIGS. 1 and 3).

(18) FIGS. 3A and 3B each show a cross-section through the outlet region of a screw spindle pump 1, 1A. FIGS. 4A and 4B show diagrammatically the arrangements of first longitudinal axis L1 of inlet channel 7, second longitudinal axis L2, L2A of outlet channel 9, 9 A and third longitudinal axis L3 of drive spindle 5 in the pump housing. Longitudinal axis L1 of inlet channel 7 is disposed orthogonal to third longitudinal axis L3 of drive spindle 5 both in the case of a screw spindle pump 1A according to the prior art and in the case of a screw spindle pump 1 according to the invention. In particular, FIGS. 3A and 4A show the prior art of a screw spindle pump 1A, wherein outlet channel 9A is disposed orthogonal to longitudinal axis L3 of drive spindle 5 (see FIG. 1) and therefore brings about a deflection of the delivered medium through approx. 90 from delivery direction FR into second flow direction SR2A (see FIGS. 1A and 1B). In the prior art according to the represented embodiment of a screw spindle pump 1A, first inflow direction SR1A and second outflow direction SR1A are thus orientated anti-parallel with respect to one another. In a conventional screw spindle pump 1A, longitudinal axis L1 of inlet channel 7 and third longitudinal axis L3 of drive spindle 5 form a plane. Second longitudinal axis L2A of outlet channel 9A is also located in this plane, i.e. first longitudinal axis L1 of inlet channel 7 and second longitudinal axis L2A of outlet channel 9A are disposed parallel with one another. According to a further embodiment (not represented), first longitudinal axis L1 of inlet channel 7 and second longitudinal axis L2A of outlet channel 9A in the prior art can each be disposed orthogonal to third longitudinal axis L3 of drive spindle 5, but not parallel with one another. This means that the two longitudinal axes L1, L2 are skewed with respect to one another and in particular do not intersect. In this case, too, the delivered medium is deflected from delivery direction FR through approx. 90 into second flow direction SR2A (see FIGS. 1A and 1B). The computer-assisted dynamic fluid simulation shows a marked eddy formation of the medium flowing out through outlet channel 9A in flow direction SR2A.

(19) In the case of inventive screw spindle pump 1 according to FIGS. 3B and 4B, on the other hand, outlet channel 9 is disposed at an obtuse angle to delivery section FS inside pump housing 2 parallel to longitudinal axis L3 of drive spindle 5. The delivered medium in the region of outlet channel 9 is thus deflected only by an angle into second flow direction SR2, wherein is less than 90. In particular, the delivered medium is deflected through an angle =180. Longitudinal axis L1 of inlet channel 7 and longitudinal axis L3 of drive spindle 5 are thus always disposed at an angle to one another that is not equal to 90, wherein the point of intersection of longitudinal axes L1 and L3 usually lies outside the pump housing. The computer-assisted dynamic fluid simulation shows a markedly reduced eddy formation of the medium flowing out through outlet channel 9 in flow direction SR2.

(20) The changes to the structure of the pump housing with a differently arranged outlet channel 9 and additional cone K, in particular concave tapering kV of cone K of the drive spindle 5, can be achieved with simple technical means without significant cost outlay. On account of the improved flow behaviour of the delivered medium, the overall efficiency of screw spindle pump 1 can be markedly increased with these low-cost changes.

(21) FIG. 5 shows a further representation of a partial region of a screw spindle pump 1. In particular, FIG. 5 shows the partial region of pump housing 2 comprising spindles 5, 6, 6*, with the outlet region comprising outlet channel 9. The partial region of pump housing 2 comprising inlet region 8 and inlet channel 7 has not been represented in order to provide a clearer representation of the arrangement of drive spindle 5 and driven female screw spindles 6, 6*. For the description of the reference symbols, reference is made in particular to FIG. 1. Furthermore, a delivery chamber for the transport of the fluid medium is denoted by reference symbol F in FIG. 5, said delivery chamber being constituted by the mutually engaging profiled regions of spindles 5, 6, 6*.

(22) The invention has been described by reference to a preferred embodiment. The person skilled in the art can however imagine that modifications or changes to the invention can be made without thereby departing from the scope of protection of the following claims.