Pump housing with dual-purpose inlet fitting

Abstract

A pump housing (4) for an eccentric screw pump, comprising a housing casing (5) extending along a housing longitudinal axis (L), a first end-face opening (6), to which a shaft seal (7) for a connection shaft (8) can be connected, and a second end-face opening (10), to which a stator (I) can be connected, and comprising a tubular inlet nozzle (11), oriented transversely to the housing longitudinal axis (L), for feeding a medium that is to be conveyed, which inlet nozzle is connected to the housing casing (5) tangentially, offset in relation to the housing longitudinal axis (L). The geometry of the inlet nozzle (11) is designed in such a way that, as the medium flows into the housing interior through the inlet nozzle (II), a flow (S) is generated which has a radial direction component (RI) directed away outwardly from the housing longitudinal axis (L) and/or an axial direction component (R2) directed towards the first end-face opening (6).

Claims

1. A pump housing for an eccentric screw pump, the housing comprising: a casing extending along a housing axis, a connecting shaft in the casing, a shaft seal at an upstream end of the casing and surrounding the connecting shaft, a stator mounted at a downstream end of the casing, and a tubular inlet fitting for the housing, projecting transversely from the housing axis for supplying a medium to be conveyed, the shape of the inlet fitting being such that a flow of medium into the housing through the inlet fitting is in an inflow direction that has a flow component directed radially outward from the housing axis and a flow component directed axially toward the upstream end, an inner cross-sectional area of the inlet fitting tapering at least partially toward the casing such that an output cross-sectional area of the inlet fitting is smaller than an inlet cross-sectional area thereof and/or is asymmetrically offset.

2. The pump housing according to claim 1, wherein the casing is essentially cylindrical at least adjacent the inlet fitting.

3. The pump housing according to claim 1, wherein an inlet cross-sectional area of the inlet fitting is asymmetrically offset axially toward the upstream housing opening and/or radially outwardly away from the housing longitudinal axis.

4. A pump housing for an eccentric screw pump, the housing comprising: a casing extending along a housing axis, a connecting shaft in the casing, a shaft seal at an upstream end of the casing and surrounding the connecting shaft, a stator mounted at a downstream end of the casing, and a tubular inlet fitting for the housing, projecting transversely from the housing axis for supplying a medium to be conveyed, the shape of the inlet fitting being such that a flow of medium into the housing through the inlet fitting is in an inflow direction that has a flow component directed radially outward from the housing axis and a flow component directed axially toward the upstream end, the inlet fitting having an inner wall shaped to form a spiral flow passage.

5. The pump housing according to claim 1, wherein the inlet fitting is offset tangentially to the axis of the casing.

6. The pump housing according claim 1, wherein the pump housing is formed by two axially joined housing sections.

7. The pump housing according to claim 1, further comprising; a bypass fitting on the pump housing at the downstream end thereof and extending transversely from the housing axis.

8. The pump housing according to claim 1, further comprising: a removable inner liner in an outer wall of the inlet fitting and shaped to impart the component(s) of flow to the medium flowing in through the inlet fitting.

9. An eccentric screw pump comprising: a pump casing extending along an axis and having an upstream end and a downstream end, a stator connected to the downstream end, a rotor in the stator, a coupling rod in the pump casing, a drive having a shaft connected to the coupling rod, a shaft seal provided on the pump casing at the upstream end for sealing around the shaft, and an inlet fitting opening into the casing adjacent the shaft seal so that medium flows into the casing through the fitting and then around the shaft seal with a component of flow directed radially outward from the axis and a component of flow directed axially toward the upstream end, an inner cross-sectional area of the inlet fitting tapering at least partially toward the casing such that an output cross-sectional area of the inlet fitting is smaller than an inlet cross-sectional area thereof and/or is asymmetrically offset.

10. The eccentric screw pump according to claim 9, further comprising: a first bypass fitting on the pump casing adjacent the downstream end and extending transversely to the axis, a pressure fitting at an end of the stator opposite the pump casing, a second bypass fitting also extending transversely to the longitudinal axis of the casing from a downstream end of the stator, and a bypass conduit extending between the bypass fittings for moving the medium between the bypass fittings from the stator output to the stator input.

11. A method of cleaning an eccentric screw pump according to claim 9, the method comprising the step of: the rotating rotor pumping the cleaning medium from the inlet fitting through the pump casing and the stator, and thereby producing flow of the medium around the shaft seal with a component directed radially outward from the axis and a component directed axially toward the upstream end.

12. An eccentric screw pump comprising: a pump casing extending along an axis and having an upstream end and a downstream end, a stator connected to the downstream end, a rotor in the stator, a coupling rod in the pump casing, a drive having a shaft connected to the coupling rod, a shaft seal provided on the pump casing and at upstream end for sealing around the shaft, and an inlet fitting opening into the casing adjacent the shaft seal so that medium flows into the casing through the fitting and then around the shaft seal with a component of flow directed radially outward from the axis and a component of flow directed axially toward the upstream end, the inlet fitting having an inner wall shaped to form a spiral flow passage.

13. A method of cleaning an eccentric screw pump according to claim 12 comprising the step of: the rotating rotor pumping the cleaning medium from the inlet fitting through the pump casing and the stator and thereby producing flow of the medium around the shaft seal with a component directed radially outward from the axis and a component directed axially toward the upstream end.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) In the following, the invention is explained with reference to drawings, which only represent embodiments. Therein:

(2) FIG. 1 shows an eccentric screw pump in a simplified view,

(3) FIG. 2 is a schematically simplified first section through an eccentric screw pump at the inlet fitting,

(4) FIG. 3 is a second section through the structure shown in FIG. 2,

(5) FIG. 4 is a simplified top view of the structure shown in FIG. 2,

(6) FIGS. 5A to 5D are views like FIG. 4 showing modified embodiments of the structure,

(7) FIG. 6 shows a second embodiment of an eccentric screw pump according to the invention,

(8) FIG. 7 is cross section A-A through the structure of FIG. 6 and

(9) FIG. 8 is section B-B through the structure of FIG. 6.

SPECIFIC DESCRIPTION OF THE INVENTION

(10) In the drawing, the basic structure of an eccentric screw pump is shown in simplified form as a stator 1, a rotor 2 rotating in the stator 1, and a drive 3 for the rotor. For example, a pump or so-called suction housing 4 is attached to the upstream suction end of the stator 1. The downstream pressure end of the stator 1 is for example constituted as a connecting piece or pressure port 15. The pump housing 4 has a casing 5 extending longitudinally along an axis L and that here is cylindrical so that the housing longitudinal axis L is the cylinder axis L.

(11) An output shaft 8 of the drive 3 rotates the rotor 2 via a coupling rod 9 that compensates for eccentric movement of the rotor 2 or its upstream end. This is done by joints or also possibly a flexible coupling rod. Details are not shown.

(12) The pump housing 4 has an upstream end 6 holding a shaft seal 7 sealing around the connecting shaft 8. Furthermore, the pump housing 4 has a downstream end 10 to which the stator 1 is fixed. In addition, the pump housing 4 has for supplying medium to be conveyed a tubular inlet fitting 11 extending transversely from the housing longitudinal axis or the cylinder axis L and connected to the casing 5. Here this inlet fitting 11 is not centered and is therefore essentially offset from the housing axis L and connected tangentially to the casing 5.

(13) In normal operation, the medium to be conveyed is fed via the inlet fitting 11 into the suction housing 4 at its upstream end 6 and is thence pumped through the stator 1 to the pressure port 15. To clean the pump, the inlet port 11 is supplied with a cleaning medium that is during operation moved by the pump through the rotor. The already mentioned decentralized, tangential connection of the inlet fitting 11 to the casing 5 creates an optimized flow around the mechanical seal 7 and thus enhances cleaning of the areas below and/or above the mechanical seal 7. According to the invention, the shape of the inlet fitting is not only tangential, rather, it is designed in such a way that the flowing medium or cleaning medium moves through the inlet fitting 11 into the interior of the housing in an inflow direction R that has a directional component R1 radially away from the axis L of the housing 4 and a component R2 axially toward the upstream end 6. For this purpose, reference is made to FIGS. 2 and 3. The direction of flow R is the direction of flow S of the medium from the transition from the inlet fitting 11 to the interior of the housing or casing 5.

(14) FIG. 3 shows that there is not exactly tangential inflow or that the direction of flow R is not exactly tangential to the inner surface of the casing 5, but is directed radially outwardly away from the housing axis L. Flow is generated, that is the flow has a radial outward component R1 of movement away from the housing longitudinal axis. FIG. 3 also shows that the inflow direction R compared to the conventional tangential orientation (or vertical) N is directed away from the radially outward with the radial direction component R1. This flow R against the inner surface of the casing creates improved circulation around the mechanical seal 7 and thus scours the inner wall of the casing 5. In addition, dead spaces below and above the mechanical seal 7 are avoided.

(15) In addition, in the embodiment according to the invention, the main flow direction H of the housing flow S is away from the upstream end 6. For this purpose, reference is made to FIG. 2 that shows how the flow S or inflow direction R is directed axially toward the upstream end 6 with directional component R2 consequently opposite to the main flow direction H of the pump. In FIG. 2 also, the conventional orientation is indicated by reference N, so that it can be seen that the direction of flow R, unlike this conventional vertical direction N, is instead toward the upstream end of the suction housing 4. This resultant axial component R2 is shown in FIG. 2. This deflection of the flow S axially against the mechanical seal 7 leads to improved cleaning of the upstream end face of the suction housing 4. Furthermore as a result, the wall areas below and/or above the mechanical seal 7 are scoured better.

(16) In the embodiment in FIGS. 2 to 4, this shape according to the invention is realized in that the cross-sectional area of the inlet fitting 11 decreases toward the casing 5 asymmetrically. This means that the cross-sectional area of an output end 11b of the inlet fitting 11 in plan view is reduced relative to that of the upper input end 11a and, in addition, is offset from the center. In the embodiment shown, the output end 11b is offset both axially toward the upstream end-face housing opening 6 and radially outward away from the housing longitudinal axis L (see FIG. 4). This creates the advantageous flow conditions described.

(17) FIGS. 5A, 5B, 5C and 5D show modifications of the embodiment according to FIG. 4. FIG. 5A shows an embodiment in which the inlet fitting compared to FIG. 4 is connected on the other side of the housing relative to the longitudinal axis L, so that the embodiment according to FIG. 5A is preferably used for a direction of rotation of the pump that is reversed from that of FIG. 4. The embodiment according to FIG. 5B differs from that according to FIG. 5A in particular by other dimensioning of the cross-sectional taper. While FIGS. 4-5A and 5B 5C show embodiments with round cross-sections, a modified embodiment with a non-round cross-section, e.g. an oval or elliptical cross-section is shown in FIG. 5D. FIG. 5D shows an optional configuration with a variably one cross section of the inlet port.

(18) FIGS. 6 to 8 show a modified embodiment of the invention, in which the asymmetrical flow S or R is generated according to the invention through a special inlet fitting 11 having a spiral-shaped inner wall 14 that forms a spiral-shaped flow passage, so that the inlet fitting 11 generates a spiral-shaped flow that as described above has a radial directional component R1 and an axial direction component R2 when it enters the interior of the housing. Also with this in the embodiment, the inflow, which is essential to the invention, can consequently be provide improved cleaning.

(19) In addition, in the embodiment according to FIGS. 6 to 8, there are two bypass ports 12 and 13 provided are connected to one another with an unillustrated bypass line. The first bypass connection 12 is connected to the suction housing 4, specifically near the downstream end 10 of the suction housing 4. The second bypass connection 13 is connected to the pressure port 15. The cleaning medium used to clean the pump also in the embodiment according to FIGS. 6 to 8, is supplied via the inlet fitting 11 and the pump conveys it through the pump by the rotor 2. In doing so, however the cleaning medium exits via the second bypass port 13 and is fed back by bypass line to the first bypass connection 12 and thus a special efficient cleaning of the pump and especially the stator can be realized. This design with bypass connections can be made in the same way in the embodiment according to the FIGS. 1 to 5 implement, that is with one of the bypass ports 12, 13 or both bypass ports 12, 13 can be connected to the inlet fitting 11 as described. The shape explained in the description and in the claims of the inlet fitting 11 consequently relates in an optional further development to invention also to one or more possibly provided bypass fittings.

(20) Furthermore, FIGS. 6 to 8 show by way of example that the pump or suction housing 4 can be made of more than one part, for example can be formed for this purpose of two housing sections 4a, 4b axially fixed together.

(21) In the invention, only one embodiment is shown in which the inlet fitting 11 is arranged eccentrically offset with respect to the longitudinal axis L of the pump. However, the shape of the inlet fitting 11 according to the invention can be used even with other than the variant shown, whereby the inlet fitting is centrally oriented to the longitudinal axis L. In such an embodiment, the shapes show for example those in the drawing can be used. The same applies to the possibility of a spiral-shaped flow passage.