CN104564655A - Eccentric screw pump, and use of eccentric screw pump - Google Patents

Abstract

An eccentric screw pump for delivering fluid and/or granular media. The pump body of the eccentric screw pump includes an inlet region, a pump unit and an outlet region. A drive unit is assigned to the inlet region. The pump unit includes a rotor and a stator, wherein the rotor moves eccentrically in the stator. The inlet region constitutes the suction side and the outlet region constitutes the pressure side of the eccentric screw pump. A bypass connection with at least one safety valve is assigned to the eccentric screw pump in order to take up and return back-flowing medium between the pressure side and the suction side of the eccentric screw pump. The bypass connection and the safety valve may also be integrated into the pump body of the eccentric screw pump.

Description

Eccentric screw pump and its application

technical field

The invention relates to an eccentric screw pump for conveying liquid and/or granular media, and to the use of such an eccentric screw pump.

Background technique

Eccentric screw pumps are pumps for conveying a wide variety of media, especially viscous, highly viscous and abrasive media such as sludge, fertilizers, crude oil and grease. Eccentric screw pumps known from the prior art comprise a rotor and a stator, wherein the rotor is accommodated in the stator and moves eccentrically in the stator. The stator consists of a housing with a helically wound interior. As a result of the movement and mutual contact of the rotors, a meandering conveying space is formed between the stator and the rotor, through which the liquid medium can be conveyed along the stator. The rotor rotates eccentrically around the stator axis or the longitudinal axis of the eccentric screw pump. The outer helix, the stator, can be in the form of a double thread, while the rotor helix is only a single thread. Eccentric screw pumps are especially suitable for the transfer of water, crude oil and many other liquids. When the rotor moves in the stator, the shape of the conveying space is constant, so the conveyed medium is not squeezed. Not only fluids but also solids can be conveyed by eccentric screw pumps when properly designed.

Excessive pressures can occur in eccentric screw pumps when conveying certain media. For this application, eccentric screw pumps require at least one safety device against excessive pressure. In the prior art, this problem was solved by arranging a connecting line between the inlet flange on the suction side of the pump body and the discharge flange on the pressure side. Connection lines are external lines and/or hose lines with integrated overflow or safety valves.

A disadvantage of the described prior art is that the connecting line is present as an external attachment of the eccentric screw pump. This therefore increases the space requirement of the eccentric screw pump in view of the required design height. In addition, external accessories run the risk of being damaged by moving loads. Until now, the need for a safety device against excessive pressure has prevented the use of eccentric screw pumps in certain fields of application. For example, it may be advantageous to use an eccentric screw pump in a borehole. However, the space here is limited by the diameter of the drilled hole. Furthermore, when inserting the eccentric screw pump into the borehole, the external piping of the eccentric screw pump risks being damaged.

The problem underlying the present invention is therefore to provide an eccentric screw pump with at least one safety device against excess pressure, characterized by a simple and uncomplicated design, which in particular does not exhibit the aforementioned disadvantages of the prior art.

The above-mentioned problems are solved by an eccentric screw with the features of the independent claim 1 . Further advantageous embodiments are described in the dependent claims.

Contents of the invention

The invention relates to an eccentric screw pump for conveying fluid and/or granular media, in particular viscous, highly viscous and abrasive media. The eccentric screw pump consists of a pump body and a drive unit. The pump body is divided into an inlet area with an inlet connection, a pump unit and an outlet area with an outlet connection. The inlet and outlet connections consist of standardized flanges for connecting other pipe sections to convey the pumped medium.

The pump unit consists of a rotor and a stator. The stator consists of a housing with a helically wound interior. The rotor is designed as a round thread screw and moves eccentrically inside the stator, so that the transfer chamber formed between the rotor and the stator is displaceable in the transfer direction.

The inlet area of the eccentric screw pump forms the suction side and the outlet area of the eccentric screw pump forms the pressure side. A bypass connection with at least one safety valve is arranged between the pressure side and the suction side. The bypass line is used to draw and return returning medium between the pressure side and the suction side of the eccentric screw pump, thereby preventing uncontrollable excessive pressure from building up inside the eccentric screw pump. Excessive pressure must be reduced in a controlled manner to hinder or prevent damage to the eccentric screw pump.

According to the invention, the bypass connection and the safety valve are integrated in the pump body of the eccentric screw pump. In particular, the bypass connection and the safety valve are integrated in the pump body of the eccentric screw pump in the region of the pump unit.

According to a first preferred embodiment of the invention, the stator comprises an additional casing. In particular, the stator is placed inside the bushing, wherein the outer circumference of the stator is smaller than the inner circumference of the bushing, so that an intermediate space is formed between the stator and the bushing. The intermediary spaces are each fluidly connected to the interior spaces of the inlet region and the outlet region and form bypass connections. Furthermore, the intermediate space is assigned at least one safety valve. If an excess pressure builds up on the pressure side of the eccentric screw pump, a part of the conveyed medium is conveyed as return flow via the intermediate space back into the inlet region of the pump body, thereby reducing the excess pressure.

According to a second preferred embodiment of the invention, the stator is accommodated inside the stator sleeve. The inner circumference of the stator sleeve corresponds approximately to the outer circumference of the stator, so that the stator sleeve lies extended over its surface area with its inner circumference abutting against the outer circumference of the stator. At least one connecting line parallel to the longitudinal axis of the eccentric screw pump is formed between the stator and the stator sleeve. The connecting line is fluidically connected to the interior space of the inlet region and the outlet region via a first connection and a second connection, respectively, and constitutes a bypass connection. The first connection and the second connection are in particular bores in the housing of the pump body, in particular in the region where the outlet region and the inlet region each adjoin the pump unit. Furthermore, at least one connecting line is assigned at least one safety valve. If an excessively high pressure builds up on the pressure side of the eccentric screw pump, a portion of the conveyed medium is conveyed as return flow via at least one connecting line back into the inlet region of the pump body.

At least one connecting line between the stator and the stator sleeve is formed by a continuous recess in the outer side surface of the stator, for example parallel to the longitudinal axis of the eccentric screw pump. For example, continuous grooves are formed on the sides of the outer surface. The recess extends along the length of the stator, in particular along the entire length of the stator.

According to a third preferred embodiment of the invention, the rotor comprises a cavity along the longitudinal axis of the rotor. The cavity may, for example, be a through hole through the rotor along its longitudinal axis. Alternatively, the cavity can be integrated in the rotor during production, so that the latter, ie the rotor, can be cast hollow accordingly or molded hollow by another suitable process. The cavities of the rotor are in fluid connection with the interior spaces of the inlet region and the outlet region, respectively, and form bypass connections. The cavity is assigned at least one safety valve. If an excessively high pressure builds up on the pressure side of the eccentric screw pump, a part of the conveyed medium is conveyed as return flow via the inner cavity of the rotor back into the inlet region of the pump body.

According to a fourth preferred embodiment of the invention, the eccentric screw pump comprises a stator with at least one return channel. Along the length of the stator, the return channel is formed parallel to the longitudinal axis of the eccentric screw pump. At least one return channel is fluidically connected to the interior of the inlet region and the outlet region and forms a bypass connection.

In particular, the area between the internal thread pitch of the stator and the outer side surface of the stator constitutes a return flow channel. The return channel does not comprise an open connection with the internal thread pitch of the stator and/or the external side surface of the stator. This means that the return channel is formed by the stator material.

The return channel is assigned at least one safety valve. If an excessively high pressure builds up on the pressure side of the eccentric screw pump, a portion of the conveyed medium is conveyed as return flow via at least one return channel of the stator back into the inlet region of the pump body. The at least one return channel is preferably cast in the stator during manufacture. Alternatively, the at least one return channel can also be formed after the stator has been manufactured.

According to one embodiment of the invention, the safety valve is arranged in the return channel, preferably in the area between the inlet area and the pump unit. According to an alternative embodiment, the safety valve is integrated in the outlet area of the pump body. Provision is made here such that the outlet opening of the safety valve leads via the first connection to the return flow channel. Multiple return channels and correspondingly arranged safety valves can also be used in this embodiment. If an excessively high pressure builds up on the pressure side of the eccentric screw pump, a portion of the conveyed medium is conveyed as return flow via at least one return channel of the stator back into the inlet region of the pump body.

The safety valves used to prevent unacceptable pressure rises in eccentric screw pumps can be spring safety valves, gravity safety valves or media safety valves. Preferably, the relief valve is a relief valve for releasing pressure from inside the eccentric screw pump in the event of an unbearably high pressure in the closed system.

The aforementioned eccentric screw pump according to the invention can be used in particular for conveying fluid and/or granular media in boreholes. Such eccentric screw pumps can generally be used whenever an excessively high pressure is expected (depending, for example, on the medium to be conveyed).

Since the return line with safety valve or overflow valve is integrated in the pump body of the eccentric screw pump, its construction remains compact. In particular, the integrated return line generally does not lead to an increase in the size of the pump body of the eccentric screw pump.

It is not only possible to integrate return lines in eccentric screw pumps with stators made of elastomer. It is also conceivable to integrate the return line in a similar manner in so-called stepping scroll pumps. Stepping scroll pumps are described, for example, in US 2008/0050249 A1. In contrast to eccentric screw pumps, such pumps do not include a stator made of rubber, which could be damaged by the conveyed medium, for example when pumping oil or the like. Instead, the pump is constructed as a stepper, consists only of corrosion-resistant metal parts and operates concentrically. Vibrations in the system can thus be eliminated, the pump can be operated at elevated temperatures and can be constructed smaller.

Description of drawings

An example of an embodiment of the invention and its advantages will be explained in more detail below with the aid of the accompanying drawings. The size ratios of the various elements in the drawings relative to each other do not always conform to the actual size ratios, as some structures are shown simplified and other structures are shown exaggerated relative to other elements for greater clarity.

Figure 1 shows an eccentric screw pump with a known bypass line according to the prior art.

Figure 2 shows an eccentric screw pump according to the invention.

Figure 3 shows a detail of an eccentric screw pump according to the invention.

Figure 4 shows a second embodiment of an eccentric screw pump according to the invention.

Figure 5 shows a third embodiment of an eccentric screw pump according to the invention.

Figure 6 shows a fourth embodiment of an eccentric screw pump according to the invention.

Figure 7 shows a fifth embodiment of an eccentric screw pump according to the invention.

list of reference signs

1 Eccentric screw pump

2 external bypass lines

3 pump body

4 Entrance area

5 pump unit

6 Exit area

7 stator

8 rotors

9 connecting rod

10 connectors

11 connectors

12 drive unit

13 drive shaft

14 teleportation space

15 Inlet flange

16 Outlet flange

20 safety valve

21 overflow valve

30 eccentric screw pump

40 relief valve

43 cavities

44 return line

45 casing

46 first connection

47 Second connection

50 stator sleeve

52 connecting pipeline

55 first connection

56 Second connection

60 cavities

62 connecting holes

65 cast return channels

66 first connection

67 Second connection

D pressure side

FR Transmission direction

L longitudinal axis

M Medium

Medium for M _R refluxing

S suction side

Detailed ways

Identical or identically acting elements of the invention are provided with the same reference symbols. Furthermore, for the sake of clarity, only the reference numerals necessary for describing the provided figures are presented in the individual figures. The presented embodiments are merely examples of how the device according to the invention may be constructed and do not represent a decisive limitation.

Figure 1 shows an eccentric screw pump 1 with a known external bypass line 2 according to the prior art. The eccentric screw pump 1 comprises a pump body 3 with an inlet region 4 , a pump unit 5 and an outlet region 6 . The inlet area 4 forms the suction side S of the eccentric screw pump 1 and the outlet area 6 forms the pressure side D of the eccentric screw pump 1 . The pump unit 5 comprises an eccentric screw conveyor, the so-called rotor 8 , which rotates in a stator 7 with a helically wound interior, forming a meandering conveyor space 14 . The rotor 8 is connected to a drive unit 12 which connects the rotor 8 to a drive shaft 13 via a coupling rod 9 arranged in the inlet region of the pump body 3 . The connecting pieces 10 , 11 are located between the latter, that is, the drive unit 12 and the rotor 8 , and are used for connection and transmission between the drive unit 12 and the rotor 8 .

The medium M conveyed into the eccentric screw pump 1 via the inlet flange 15 of the inlet region 4 is conveyed through the pump unit via the meandering conveying space 14 in the conveying direction FR and is conveyed from the eccentric screw pump 1 via the outlet flange 16 of the outlet region 6 . 1 pump out. A bypass line 2 with a safety valve 20 (for example an overflow valve 21 ) is arranged between the outlet flange 16 and the inlet flange 15 via suitable connecting devices 17 , 18 . In particular, the overflow valve 21 is arranged directly on the connecting device 17 assigned to the outlet flange 16 . The bypass line 2 runs parallel to the pump body 3 between the overflow valve 21 and the connection 18 assigned to the inlet flange 15 .

With the presented safety circuit, when an excessively high pressure builds up on the pressure side of the eccentric screw pump 1 , a part of the delivered medium M is delivered as return flow _MR back to the inlet flange 15 and forward into the inlet of the pump body 3 area 4.

Figure 2 shows an eccentric screw pump 30-1 according to the invention. Wherein, the pump body 3 is integrated with at least one overflow valve 40 . In particular, the stator 7 is surrounded by a sleeve 45 . The housing of the pump body 3 comprises a first connection 46 to the sleeve 45 in the outlet area 5 so that the inner space of the outlet area 5 is fluidly connected to the cavity 43 formed between the sleeve 45 and the stator 7 . Furthermore, the housing of the pump body 3 comprises a second connection to the sleeve 45 in the inlet area 4 , so that the inner space of the inlet area 4 is fluidly connected to the cavity 43 formed between the sleeve 45 and the stator 7 . Therefore, a return passage is formed between the sleeve 45 and the outer side surface of the stator 7, and when an excessively high pressure occurs in the eccentric screw pump 30-1, a part of the medium M _R can pass through this passage from the eccentric screw pump 30-1. The pressure side D returns to the suction side S. The returning medium _MR leads to the inlet region 4 of the pump body 3 and is conveyed again in the conveying direction FR through the eccentric screw pump 30 - 1 .

One or more overflow valves 40 for limiting the delivery pressure of the eccentric screw pump 30-1 are also placed in the cavity 43 or in the two connections 47 in the cavity 43 and in the inlet area 4 of the pump Between the interior of the pump body 3 , the outlet of said overflow valve leads to the interior of the pump body 3 in the inlet area 4 . The arrangement of the overflow valve 40 in the cavity 43 is represented in detail in FIG. 3 .

Figure 4 shows an eccentric screw pump 30-2 according to the present invention. Wherein, at least one overflow valve 40 is integrated in the pump body 3 . In particular, the stator 7 - 2 is surrounded by a stator sleeve 50 . Between the stator 7-2 and the stator sleeve 50, at least some sections form connecting lines 52 parallel to the longitudinal axis L of the eccentric screw pump 30-2. At the pressure-side end of the eccentric screw pump 30 - 2 , the connecting line 52 comprises a first connection 55 to the interior of the eccentric screw pump 30 - 2 in the outlet area 6 . Furthermore, at the suction-side end of the eccentric screw pump 30 - 2 , the connecting line 52 comprises a second connection 56 connected to the interior of the eccentric screw pump 30 - 2 in the inlet region 4 . The first connection 55, the connecting pipeline 52 and the second connection 56 form a return passage, and when an excessively high pressure occurs in the eccentric screw pump 30-2, a part of the medium M _R can pass through the return passage from the pressure of the eccentric screw pump 30-2. Side D returns to suction side S. The returning medium M _R leads to the inlet region 4 of the pump body 3 and is conveyed again in the conveying direction FR through the eccentric screw pump 30 - 2 .

One or more relief valves 40 for limiting the delivery pressure are arranged in the connecting line 52 or between the connecting line 52 and a second connection 56, wherein the second connection 56 is located on the suction side S of the eccentric screw pump 30-2 superior.

Figure 5 shows a third embodiment of an eccentric screw pump 30-3 according to the invention. Here, a rotor 8-3 that is at least partially hollow is used. The rotor 8-3 includes a cavity 60 extending along the rotor longitudinal axis _LR . Furthermore, the rotor 8-3 comprises at its drive end a connection hole 62 between the outer side surface of the rotor 8-3 and the cavity hole 60 for creating the cavity 60 and the pump in the inlet region 5 of the eccentric screw pump 30-3. Fluid connections between the interiors of the bodies 3. An overflow valve 40 is also integrated in the cavity 60 . The cavity 60 of the rotor 8-3 and the connecting hole 62 form a return channel. When the pressure is too high in the eccentric screw pump 30-3, a part of the medium M _R can pass through the return channel from the pressure side of the eccentric screw pump 30-3. D returns to suction side S. The returning medium M _R leads to the inlet region 4 of the pump body 3 and is conveyed again in the conveying direction FR through the eccentric screw pump 30 - 3 .

Figure 6 shows a fourth embodiment of an eccentric screw pump 30-4 according to the invention. The stator 7-4 employed here includes cast return channels 65 parallel to the rotor longitudinal axis _LR , which form a fluid connection with the interior of the pump body 3 in the outlet region 6 and with the interior of the pump body 3 in the inlet region 4. connect. In the event of an excessively high pressure in the eccentric screw pump 30-4, a part of the medium _MR can flow back from the pressure side D of the eccentric screw pump 30-4 to the suction side S via the return channel 65, wherein in each case the return channel 65 At least one overflow valve 40 is arranged in it. The returning medium M _R leads to the inlet region 4 of the pump body 3 and is conveyed again in the conveying direction FR through the eccentric screw pump 30 - 4 .

The overflow valve 40 can also be integrated and arranged in the pump body, so that the medium _MR flowing back through the return channel 65 of the stator 7-4 first flows through the overflow valve 40 before passing into the inlet area 4 of the pump body 3 .

Figure 7 shows a fifth embodiment of an eccentric screw pump 30-5 according to the invention. The stator 7 - 5 here also includes a return flow channel 65 . It is fluidly connected to the interior of the pump body 3 in the outlet area 6 and the interior of the pump body 3 in the inlet area 4 via a first connection 66 and a second connection 67 , respectively. In the present exemplary embodiment, an overflow valve 40 * is integrated in the outlet area 6 of the pump body 3 in the vicinity of the pressure connection. The outlet opening of the overflow valve 40 * leads to one or more first connections 66 and thus to one or more cast return channels 65 .

The invention has been described with reference to the preferred embodiments. However, modifications or changes to the present invention conceivable by those skilled in the art will not depart from the protection scope of the following claims.

Claims (13)

1. An eccentric screw pump (1, 30) for conveying fluid and/or granular media (M) with a pump body (3) comprising an inlet region (4), a pump unit ( 5) and the outlet area (6), where the pump unit (5) consists of a rotor (8) and a stator (7), where the rotor (8) can move eccentrically in the stator (7), where the inlet area (4) forms the suction side (S) of the eccentric screw pump (1, 30), the outlet area (6) forms the pressure side (D) of the eccentric screw pump (1, 30), and wherein the eccentric screw pump (1, 30) is distributed with Bypass connection (2) with at least one safety valve (20) for suction and return of return medium between pressure side (D) and suction side (S) (1,30) of eccentric screw pump (1,30) (M _R ), characterized in that the bypass connection and safety valve (40) are integrated in the pump body (3) of the eccentric screw pump (30). 2. The eccentric screw pump (30) according to claim 1, characterized in that the bypass connection and safety valve (40) are integrated in the eccentric screw pump (30) in the region of the pump unit (5). in the pump body (3). 3. The eccentric screw pump (30) according to claim 1 or 2, characterized in that, the stator (7) is arranged in the sleeve (45), and wherein the stator (7) and the sleeve (45) An intermediate space (44) is formed therebetween, which is fluidly connected to the respective inner spaces of the inlet region (4) and the outlet region (6) and constitutes a bypass connection. 4. The eccentric screw pump (30) according to claim 1 or 2, characterized in that the stator (7-2) is arranged in a stator sleeve (50), and wherein the stator sleeve (50) is extended Placed on its surface area with its inner circumference against the outer circumference of the stator (7-2), and wherein the stator (7-2) and the stator sleeve (50) are formed parallel to the eccentric screw pump (30 ) of the longitudinal axis (L) of at least one connecting line (52), which is connected via a first connection and a second connection (55, 56) to the respective inner spaces of the inlet area (4) and the outlet area (6) connection, and constitute a bypass connection. 5. The eccentric screw pump (30) according to claim 4, characterized in that at least one connecting line (52) is in particular formed by a stator (7-2) parallel to the longitudinal axis (L) of the eccentric screw pump (30) ), wherein said recesses extend along the length of the stator (7-2), in particular along the entire length of the stator (7-2). 6. Eccentric screw pump (30) according to claim 1 or 2, characterized in that the rotor (8-3) comprises a cavity (60) along the rotor longitudinal axis (L _R ), the cavity It is in fluid connection with the respective inner spaces of the inlet area (4) and the outlet area (6) and constitutes a bypass connection. 7. The eccentric screw pump (30) according to claim 1 or 2, characterized in that, the stator (7-4) comprises at least one return channel (65), and the return channel (65) is parallel to the eccentric screw pump The longitudinal axis (L) of (30) constitutes and extends along the length of the stator, wherein at least one return channel (65) is in fluid connection with the respective inner spaces of the inlet area (4) and the outlet area (6) and constitutes a bypass connection . 8. The eccentric screw pump (30) according to claim 6, characterized in that, the return channel (65) is between the inner thread pitch of the stator (7-4) and the outer side surface of the stator (7-4) and wherein the return channel (65) does not include any open connection with the internal thread pitch of the stator (7-4) and/or with the outer side surface of the stator (7-4). 9. Eccentric screw pump (30) according to claim 6 or 7, characterized in that at least one return channel (65) is cast in the stator (7-4). 10. The eccentric screw pump (30) according to any one of claims 6 to 8, characterized in that the safety valve (40) is arranged in the return channel (65), in particular wherein the safety valve (40) Arranged in the area between the inlet area (4) and the pump unit (5). 11. The eccentric screw pump (30) according to any one of claims 6 to 8, characterized in that the safety valve (40*) is integrated in the outlet area (6) of the pump body (3), And wherein the outlet opening of the safety valve (40*) leads to the return channel (65) via the first connection (66). 12. Eccentric screw pump (30) according to any one of the preceding claims, characterized in that the safety valve (40, 40*) is an overflow valve. 13. Use of an eccentric screw pump (30) according to any one of the preceding claims for conveying fluid and/or granular media (M) in boreholes.