HK1114654B - A rotary displacement pump - Google Patents

Description

Rotary displacement pump

Technical Field

The present invention relates to a rotary displacement pump of the type known as "sine pump" (the company MASOProcess-Pumpen GmbH, 74358I llsfeld, Germany has for many years called "sine pump"). Such pumps comprise a rotatable disc having an undulating configuration (i.e. at least one of the front surfaces of the disc does not form a plane perpendicular to the axis of rotation of the disc, but exhibits a periodic variation in distance from an imaginary central plane of the disc when travelling along a circumferential path about the axis of rotation). The disc, more precisely the radially projecting plate of the rotor, engages with a scraper which is fixed in the circumferential direction of the pump and is free to reciprocate in the substantially axial direction of the pump, thereby "following" the axial oscillating movement of the plate. At one side of the scraper, i.e. at the suction side of the pump, the "chamber" is open and gradually increases in size due to the rotation of the rotor. At the other side of the scraper, i.e. the pressure side of the pump, the size of those "chambers" is gradually reduced by the rotation of the rotor, because the scraper prevents the material contained in the chambers from continuing to move along a circular path.

Such pumps are well known in the art. Such pumps are suitable for a variety of applications, but the most important field of application is in the food industry, chemical and biochemical industry, medical industry and cosmetics industry for pumping flowable, relatively viscous materials. Yogurt, soup, sauce, mayonnaise, fruit juice, cheese material, chocolate, paint, cosmetic cream, lipstick material may be mentioned as a small selection of materials that can be pumped by means of the pump according to the invention.

Background

Sinusoidal pumps and motors (similar in design to pumps but utilizing pressurized fluid to generate drive torque) are known in a variety of configurations.

Us patent No.3,156,158 discloses a dental drill apparatus comprising a sinusoidal motor. The housing of the motor has a hollow cylindrical configuration. The stator is disposed in the housing to contact the outer peripheral surface of the rotor plate over a range of up to about 180 °. The stator has a generally sleeve-type configuration, but does not extend for 360 ° of full circle and includes axially extending interrupted slots to secure the flights through such slots. Sealing of the motor to prevent leakage of the working fluid is achieved by sealing rings placed close to the axial ends of the housing and relatively far from the rotor plates and the inlet and outlet holes.

The company MASO Process-Pumpen GmbH, 74358 Illsfeld, Germany has produced and sold for many years sinusoidal pumps with a stator that extends along the inner circumference of the housing, over an extent of more than 180 °. The portions of the housing forming the inlet and outlet chambers are not in line with the stator. The flights are supported in the housing by complex support members.

It is an object of the present invention to provide a sine pump which allows for a relatively simple and inexpensive way of manufacturing.

It is another object of the present invention to provide a sine pump that allows Cleaning In Place (CIP) to be performed in an efficient manner.

Disclosure of Invention

According to the invention, a rotary displacement pump comprises:

(a) a stator;

(b) a rotor including a shaft portion and a radially projecting plate having an undulating disk-type configuration;

(c) a scraper comprising an engagement slot having a predetermined radial height and a predetermined axial width, the engagement slot engaging the projecting plate of the rotor;

(d) the stator comprises a first substantially cup-shaped member and a second substantially cup-shaped member and defines a circumferential wall;

(e) the scrapers are arranged within the stator, supported to be fixed in a circumferential direction and allowed to reciprocate in a substantially axial direction;

(f) the stator and the scraper together define:

an inlet chamber of the pump having an inlet aperture,

an outlet chamber of the pump having an outlet orifice,

and a channel extending from the inlet chamber to the outlet chamber,

the scraper forms a partition between the inlet chamber and the outlet chamber, and the plate of the rotor is rotatable through the inlet chamber, the channel, the outlet chamber, and the slot of the scraper.

The radially projecting plates (or "wave discs") may be an integral part of the rotor. However, the disc is more preferably a workpiece that is machined separately from the shaft portion of the rotor and is secured to the shaft portion after machining. The shaft portion and the disk portion are generally formed of metal.

When scanning the faces of the slabs in the circumferential direction (as is the case when viewed in the radial direction towards the centre of the rotor), one or both faces of the disk preferably follow a mathematical sinusoid exactly or approximately. The plate preferably undergoes two complete periods of sinusoidal lines in its 360 ° circle, so that there are two chambers at each side of the plate, all four chambers being 90 ° apart along the 360 ° circle. However, any other type of undulating configuration is also possible, for example comprising a curvature with a constant radius instead of a curvature according to a sinusoid. The radius of curvature should not be too small to facilitate cooperation with the squeegee.

The engagement slots of the scraper have a shape such that they can engage with the blades of the rotor even if the blades are not planar. As a result, there are curved transitions at the inlet and outlet sides of the flight and at both sides of the slab. At the radially inner ends of the slots, there are typically curved transitions into the radially inner faces of the flights that accommodate the curved transitions between the respective faces of the plates and the adjacent cylindrical surface of the hub of the disc.

With respect to the stator, the term "generally cup-shaped member" is intended to be used generally to describe the overall configuration of the stator member in practice. The term does not mean that the bottom of the "generally cup-shaped member" is generally flat and closed (as is the case with most drinking cups). The embodiments of the invention shown in the figures will show the broad meaning intended to be expressed as "generally cup-shaped". The stator preferably comprises two cup-shaped members and no additional members (auxiliary elements such as sealing elements or fastening elements are not considered).

The stator preferably forms a cylinder liner secured in the housing of the pump. This design allows for an optimal choice of materials for the housing and the cylinder liner. On the other hand, it is possible to produce a pump having a stator that performs the function of a housing and a housing that does not house the stator. If present, the housing preferably comprises the following main components: the device comprises a cylindrical body, two circular end plates and two pipe sleeves; the rest parts are auxiliary parts such as screws, fastening pins and the like. The main part is preferably made of metal. Stainless steel is a very suitable material, but other metals that are not attacked by the material to be pumped are also suitable. The body of the housing makes it possible to use a tubular workpiece, requiring only minimal machining of the inner periphery and the two front faces. The end plates also require minimal machining. The two sockets are usually welded to the body of the housing, which body of course has two radial openings for inserting the socket ends.

The first and second stator members are preferably formed from a plastics material, more preferably from a duroplastic resin. Polyamides are particularly preferred materials because of their high strength, low thermal expansion and low moisture absorption. Other suitable plastic materials exist such as Polyetheretherketone (PEEK). The materials already described for the stator also apply to the preferred materials for the scraper. It is not mandatory that the stator and the scraper comprise the same material.

The stator component may have a moulding accuracy such that no subsequent machining is required. Alternatively, machining may be performed after molding.

The first and second stator members preferably abut each other in a first abutment region having a circular arc (typically about 160 ° to 210 ° long, depending on the size of the inlet and outlet apertures) configuration and in a second abutment region having a circular arc (typically 10 ° to 60 ° long) configuration. The inlet aperture is preferably formed by a pair of first recesses in the circumferential wall portions of the first and second stator members. Each recess may have a substantially semicircular shape when viewed in the radial direction. The outlet holes may be formed in a similar manner.

Sealing of the stator elements is preferably effected close to the abutment region and close to the inlet and outlet holes to prevent leakage of pumped material into the (usually narrower) space between the housing and the stator, in order to keep the region of the housing that is contaminated by the pumped material small. A preferred design is to provide a first sealing member, preferably an O-ring, at the first stator member, which extends at a small distance and substantially parallel to the abutment region and the inlet and outlet apertures, and to provide a second sealing member at the second stator member in a similar manner. Preferably, a groove for accommodating the sealing member may be formed in an outer surface of the circumferential wall portion of the stator member at the same time as the molding of the stator member.

A second preferred design is to provide an integrally formed sealing member which is placed in grooves provided in the first and second abutment regions and in grooves provided in the outer surface of the circumferential wall portion substantially parallel to the inlet and outlet apertures.

A third preferred design is to provide an integrally formed sealing member which is placed in grooves provided in the first and second abutment areas and in grooves provided in the wall portions of the inlet and outlet openings. Those sections of the integrally formed sealing member which are located in the grooves provided in the wall portions of the inlet and outlet bores will engage with the cylindrical outer surface of the respective socket. This third preferred design is particularly suitable if there is no housing accommodating the stator and the sleeve is fastened to the stator.

The second and third preferred seal designs may be modified to replace the integrally formed seal member with four seal members, one for the length of the first abutment region and one for the length of the second abutment region, and two surrounding the inlet and outlet apertures (in grooves in the cylindrical outer surface of the stator or in grooves in the wall portions of the inlet and outlet apertures), respectively.

Alternatively, the seal between the stator and the shroud may be achieved by a sealing ring located in a circumferential groove of the shroud. This alternative may be practiced with isolated sealing rings or with corresponding sections of the integrally formed sealing member.

In principle, it is possible to mount the scrapers directly in the stator material. It is however more preferred to provide guide members which are secured within the stator and provide support for the scrapers, i.e. secure the scrapers in the circumferential direction and allow the scrapers to move to and fro in a substantially axial direction. In this way, it is possible to more easily avoid the occurrence of wear by the reciprocating movement of the blade.

The guiding means of the scraper blade substantially have a concave configuration. The concave plate is easier and less expensive to manufacture than the complex work pieces that provide guidance in conventional sinusoidal pumps. The guide means, with or without the recess configuration, are preferably made of metal.

An alternative way of securing the guiding means of the scraper with respect to the housing, which is particularly simple and preferred, is to place at least part of its edge region in a groove of the stator. Those grooves may be formed at the same time as the stator member is molded and/or may be machined.

The scraper preferably engages the guide means by means of a suitable groove having a predetermined depth. This will be explained more specifically for one embodiment of the invention shown in the drawings.

The rotor is preferably not supported by bearings arranged in the stator or the housing, but by bearings arranged beside the stator or the housing. The entire pump (not considering its drive motor, typically an electric motor) preferably comprises a bearing portion of the bearing housing the rotor, and the stator or the housing (i.e. pump housing features) is fastened to the bearing portion.

It should be emphasized that the invention relates not only to the whole of the pump but also to its constituent parts. In particular, the stator disclosed herein is another subject of the present invention, the guiding device disclosed herein is another subject of the present invention, the scraper disclosed herein is another subject of the present invention, the guiding device and scraper assembly disclosed herein is another subject of the present invention, and the seals and sealing members disclosed herein are another subject of the present invention.

Drawings

The invention will be described in more detail below with reference to an embodiment as described below and as shown in the drawings.

FIG. 1 shows a side view and a partial axial cross-sectional view of a complete pump;

FIG. 2 is a front view and a partial sectional view along II-II of the pump shown in FIG. 1;

FIG. 3 is a radial view of the stator of the pump shown in FIG. 1, viewed in the direction of arrow III shown in FIG. 2;

FIG. 4 shows an axial cross-sectional view of a pump portion of the pump of FIG. 1, taken on a larger scale than that of FIG. 1;

FIG. 5 shows a front view of the first stator member as viewed in the direction of arrow V shown in FIG. 1;

fig. 6 shows a side view of the guiding means of the scraper and on a larger scale than in fig. 1;

FIG. 7 shows a side view of the squeegee, and the scale used in the side view is larger than the scale used in FIG. 1;

FIG. 8 shows the screed of FIG. 7 viewed in the direction of arrow VIII of FIG. 7;

FIG. 9 shows the screed of FIG. 7 viewed in the direction of arrow IX shown in FIG. 7;

FIG. 10 shows an integrally formed sealing member constructed in the plane of the drawing; and

figure 11 shows a front view of a detail of the sealing member shown in figure 10.

Detailed Description

Fig. 1 shows the entire pump 2, which comprises a pump part 4 or pump feature 4 and a bearing part 6. The pump feature 4 will be described in more detail in connection with fig. 2 to 9. The support portion 6 will be further described below. On the right-hand side in fig. 1, the end of the shaft 8 projects from the bearing part 6. The drive motor, not shown in the figures, typically an electric motor, applies torque to the shaft 8 by being coupled directly to the shaft 8 or coupled to the shaft 8 through a coupling or, for example, through gears or pulleys.

Referring now to fig. 4, the left hand portion of the shaft 8 can be seen. The disc member 10 is keyed to the shaft 8 and rotates with the shaft 8. Hereinafter, the disc member 10 will be referred to as "disc 10". The shaft 8 and the disc 10 are part of a rotor.

The disc 10 comprises radially projecting blades 12. The plate 12 has an axial thickness 14 and a predetermined outer diameter. The plate has a right hand (front) surface 16 and a left hand (front) surface 18. If for example a fingertip is used and for example travels along a circumferential line of the outer diameter, i.e. the surface 16, the fingertip will, as seen in a radial view, describe a curved sinusoidal profile (not necessarily a strictly mathematical sinusoidal profile) which undulates with respect to a central plane crossing the axis of the shaft 8 at right angles. There are two complete cycles of the sinusoid along a 360 circle, the first time from the full left hand side shown in figure 4 to the full right hand side shown in figure 4 and back, and the second time from the full left hand side shown in figure 4 to the full right hand side shown in figure 4 and back. The description made in connection with the right-hand face 16 applies equally to the left-hand face 18.

The pump feature 4, hereinafter referred to simply as "pump 4", comprises a housing 20 having the following main components: a tubular cylindrical body 22, a right-hand circular first end plate 24, a left-hand circular second end plate 26, an inlet shroud 28 (see fig. 2), and an outlet shroud 30 (see fig. 2). In addition, there are three screws 32 angularly spaced 120 ° apart for securing the end plate 24 to the body 22, three screws 34 angularly spaced 120 ° apart for securing the end plate 26 to the body 22 with handles 36, and an axially extending retaining pin 38 to be described later. The sockets 28, 30 are welded to the body 22 (not shown) and have threads (not shown) at their radially outer ends to allow connection of external pipes. The axes of the two sleeves 28, 30 intersect at 90 °. The body 22 has two openings 40 corresponding to the sockets 28, 30.

The body 22, end plates 24, 26, and sleeves 28, 30 comprise stainless steel.

The stator 42 follows the inner surface of the housing 20 completely (lines). The stator 42 includes a first generally cup-shaped stator member 44 (right-hand side in fig. 4) and a second generally cup-shaped stator member 46 (left-hand side in fig. 4). Fig. 5 shows the first stator member 44 as viewed in the direction of arrow V shown in fig. 4.

The bottom wall of the first stator member 44 at its lower portion (constituting about the lower half of the first stator member 44) has a substantially greater thickness 48 than the thickness 50 of the first stator member 44 at its upper portion. The first stator member 44 includes a cylindrical opening 52 in a central portion thereof, which is defined at a lower portion thereof by a thick bottom wall and at an upper portion thereof by a cylindrical wall portion 54. The right hand front face of the bottom wall of the first stator member 44 is planar. The left hand front face of the first stator member 44 is also planar.

Generally speaking, the second stator member 46 is a mirror image of the first stator member 44, with the most relevant exception of the absence of a central opening, but a completely closed bottom wall. Another related exception is the circular recess 56 in the right hand front face of the first stator member 44. The recess 56 receives an end of an outer distance sleeve 58.

The left hand front face 60 of the first stator member 44 and the right hand front face 62 of the second stator member 46 abut one another. There is an actual upper first abutment region 64 that is "about 40" long and an actual lower second abutment region 66 that is about 200 "long. Between the first 64 and second 66 abutment regions there is an inlet aperture 68 of the stator 42 and between the second 66 and first 64 abutment regions there is an outlet aperture 70 of the stator 42. The inlet and outlet apertures 68, 70 are circular in radial view and correspond in diameter and position to the opening 40 in the body 22 of the housing 20. However, the inlet and outlet apertures 68, 70 may have smaller or larger dimensions than the opening 40.

The above-mentioned retaining pin 38 serves to secure the stator components against rotation by securing the first and second stator components 44, 46 relative to the end plates 24, 26 of the housing 20. The first and second stator members 44, 46 are clamped against each other between the end plates 24, 26 of the housing 20.

First and second sealing members 72, 74, respectively in the form of O-rings, are used to seal the stator members 44, 46 to prevent pumped material from leaking into the space 76 (narrow gap) between the stator 42 and the housing 20. In the portion of the first stator member 44 without the inlet or outlet apertures 68, 70, a first sealing member 72 is provided at the outer periphery of the first stator member 44, at a position proximate to the first and second abutment regions 64, 66. In the portion of the first stator member 44 where the inlet aperture 68 or the outlet aperture 70 is present, a first sealing member 72 is also provided at the circumferential wall, but over a small distance follows a semi-circle of the inlet aperture 68 and a semi-circle of the outlet aperture 70. The same description similarly applies to the second seal member 74 disposed outside the circumferential wall portion of the second stator member 46. The first and second seal members 72, 74 are each located in a groove 78. Fig. 3 illustrates the manner in which the grooves 78 and the sealing members 72, 74 encircle the stator members 44, 46.

The hub in the disk 10 is clamped in the axial direction against the inner spacer sleeve 80 by a threaded nut 82. The right hand front face of the inner distance sleeve 80 abuts against a shoulder 84 of the shaft 8. The hub portion of the disk 10 has a right hand front face 86 in sliding contact with the first stator member 44 and has a left hand second front face 88 in sliding contact with the second stator member 46. Those sliding contacts provide a certain sealing effect. A complete seal is achieved by a lip seal ring 90 located between the fixed outer distance sleeve 58 and the rotating inner distance sleeve 80. A sliding ring seal may be used as an alternative.

The portion of the right-hand face 16 of the plate 12 that projects to the greatest extent in the axial direction and the portion of the left-hand face 18 of the plate that projects to the greatest extent in the axial direction are in contact (in the form of radial contact lines) with the stator 42.

Fig. 6 shows the guide 92 on a larger scale. The guide 92 is a rectangular metal plate having a substantially rectangular recess 94 at its middle portion. The guide 92 is secured in the stator 42 by grooves in the stator members 44, 46. There are axially extending grooves 96 in the inner surface of the circumferential wall of the stator members 44, 46. At the inner side of the bottom wall of the first stator member 44 there is a radially extending groove 98. There is a radially extending groove 100 in the inner surface of the bottom wall of the second stator member 46. There is a groove 102 extending in the axial direction in the wall portion 54 of the first stator member 44. And there are axially extending grooves 104 in the respective wall portion 54 of the second stator member 46. All of those trenches 96, 98, 100, 102, 104 lie in the same plane, which is indicated by dashed line 106. In the assembled state as shown in fig. 4, all four edge regions 108 of the guide 92 (i.e. the long and short edges of the rectangular plate) extend into the grooves 96, 98, 100, 102, 104. In this way, the guide 92 is secured in both axial directions, in both radial directions and in the circumferential direction.

Fig. 7, 8 and 9 show the squeegee 110. The flight 110 has a generally rectangular plate configuration but has an engagement slot and a plurality of grooves to be described below. The thickness of the flight 110 is about 5 times the thickness of the guide 92. The guide 92 and the flight 110 have a common central plane.

The flight 110 has a cross-engagement slot 112 that extends generally in a circumferential direction. When viewing the interior of the engagement slot 112 in a radially outward direction (see fig. 8), it can be seen that there are four curved transitions 114 between the narrowest portion 116 of the engagement slot 112 and the large area flat surface 118 of the flight 110 (facing both circumferential directions). The axial dimension 116 of the engagement slot 112 at its smallest part is only slightly wider than the axial dimension 14 of the plate 12 of the impeller disc 10, so that the engagement slot 112 can be placed on the plate 12 with the scraper 110 straddling the plate 12. The curved transition 114, unlike the planar configuration, allows for a curved or wavy configuration of the plate 12.

The flight 110 further has a first groove 120 extending along a radially outer edge surface 122 thereof. The flight 110 further has a second groove 124 extending in a radial direction along a front end surface 126. The flight 110 further has a third groove (not shown) extending in a radial direction along the other front end surface 128 thereof. All three grooves 122, 124 have a predetermined depth (the radially extending groove 124 is much deeper than the first groove 120) and have a width only slightly wider than the thickness of the guide 92. To assemble the scraper 110 and the guide 92, the scraper 110 can slide over the guide 92 in the direction of arrow a (as shown in fig. 6 and 7). In the assembled state, the wiper 110 "fills" the recess 94, leaving of course the engagement slot 112 open. The three grooves 120, 124 accommodate three edge regions 130 or rims along the recess 94 of the guide 92 in a sandwich-like manner. The radially extending edge region 130 of the guide 92 and the bottom surface 131 of the second and third radially extending grooves 124 of the scraper 110 are at a distance from each other such that the scraper 110 can follow the undulating configuration of the impeller disk 10 in both axial directions. In fig. 4, a radial line 132, drawn as a "line dot-dot". the leading edge surfaces 126, 128 of the blade 110 are shown. The situation shown in fig. 4 is the left hand extreme position of the squeegee 110.

Referring again to fig. 1, it is now shown how the rotatable shaft 8 is supported in the support portion 6. Two angled roller bearings are provided spaced apart within the housing of the bearing portion. The inner race of the roller bearing 134 is secured to the shaft 8. The shaft 8 projects beyond the bearing portion 6 in the left-hand direction and extends into the pump feature 4 in a cantilevered manner. The outer insulating sleeve 58 abuts at its right-hand front face against a positioning face 136 of the bearing part 6. The housing 20 of the pump feature 4 is fastened in the axial direction against the bearing part 6 by three screws (not shown) spaced 120 deg. apart.

In order to assemble the pump feature 4 with the bearing portion 6 and the shaft 8 protruding from the bearing portion 6, the outer distance sleeve 58 is inserted first, followed by the three lip seal rings 90. The assembly of first end plate 24, right retaining pin 38, first stator member 44, and body 22 is then slid over outer spacer sleeve 58; after which an inner distance sleeve 80 is inserted. The scraper 110 and guide 92 are then assembled together at a separate location, in the direction of arrow a, as described above, and this "sandwich" structure is placed on the sheet 12 of the tray 10. Thereafter, the disc 10 comprising the scraper 110 and the guide 92 is slid in the axial direction over the left-hand end of the shaft 8, the three edge regions 108 of the guide 92 entering the grooves 96, 98, 102 of the first stator member 44. Next, the nut 82 may be put in place and tightened. Thereafter, the second stator member 46 and the left retaining pin 38 and second end plate 26 are placed in position. The screw 34 is tightened.

Referring to fig. 2, 4, 5, it can be seen that pump 4 includes an inlet chamber 138 (adjacent first sleeve 28, opening 40 and inlet aperture 68) followed by a generally semicircular channel 140 followed by an outlet chamber 142 (adjacent outlet aperture 70 and opening 40 and sleeve 30). The inlet and outlet chambers 138, 142 have a larger axial dimension than the channel 140. The inlet chamber 138 and the outlet chamber 142 are separated from each other by a "sandwich structure of the scraper 110 plus the guide 92". The outer edge surface 122 of the scraper 110 contacts the inner surface of the stator 42, and the recessed (see fig. 9) inner edge surface 144 of the scraper 110 contacts both wall portions 54 of the stator 42.

The stator 42 and the blades 110 are preferably made of polyamide. Polyamide named "Polyamide 12" is particularly suitable for stator 42 and Polyamide 6 "is particularly suitable for blade 110.

The stator 42 may be produced in a molding process, comprising the grooves 78 for the sealing members 72, 74 and comprising the grooves 96, 98, 100, 102, 104 for the edge regions 108 of the guiding means 92. It is also possible to manufacture the blade 110 by a moulding process, but in this case it is more reasonable to machine the slots 112, 120, 124 in particular.

If, as an alternative, the pump 4 is designed without a housing 20 accommodating the stator 42, the first and second stator members 44, 46 can be fastened to each other simply by any suitable means, for example and preferably by a plurality of tie bolts distributed along the cylindrical outer surface of the stator 42 and extending in the axial direction. Such tie bolts may have ends that engage the outer front faces of the first and second stator members 44 and 46. The sleeves 28 and 30 need to be secured to the stator 42. A preferred alternative is to provide each of the sockets 28 and 30 with a flange, for example circular, fastened to a mating plane provided at the outside of the stator 42. It is possible to seal the respective socket 28 or 30 against the stator 42 by using the cylindrical outer surface of the socket and the cylindrical surface of the inlet or outlet hole 68 or 70, respectively, or by using a contact plane between the flange of the socket and a mating plane of the stator 42.

It will be appreciated that the pump of the present invention can be manufactured at relatively low cost. The number of parts is small, not all parts need to be machined, and in particular for the housing 20, only little and uncomplicated machining is required.

A typical amplitude of the wave-like motion performed by the plates 12 of the disc 10 is 20 mm.

Fig. 10 shows an integrally formed sealing member 150 that may be used in place of the two O-rings 72, 74. In contrast to the first embodiment described above, this variation integrates those portions of the O-rings 72, 74 that extend in parallel (i.e., the portions without the inlet or outlet apertures 68, 70) into one strand 152 and places the strand within a pair of grooves provided in the first and second abutment regions 64, 66. At both ends of each abutment region 64, 66, the integrally formed sealing member 150 has a step 154 (see fig. 11) as a transition to a larger diameter groove disposed in the outer surface of the circumferential wall of the stator 42 and at a close distance from the inlet and outlet apertures 68, 70 as in the first embodiment.

Fig. 10 shows exactly another alternative integrally formed seal member 150, but without the step 154. The circular section 156 will be located in grooves provided in the wall of the inlet and outlet apertures. Circular section 156 will engage the cylindrical outer surfaces of sleeves 28 and 30.

The description that has just been given has shown that the position of the sealing member 72, 74 or 150 is so close to the chamber 138, 142/channel 140 filled with the material to be pumped that Cleaning In Place (CIP) is possible in a simple and very efficient manner. Any cleaning liquid will easily reach the sealing member 72, 74 or 150 in a short time. There is little need to disassemble the pump 4 for cleaning purposes.

As another alternative, the shaft 8 may be supported by a slide bearing in the stator 42 rather than in the support portion 6.

As a typical example, the pump of the invention may be designed for use in situations where the back pressure is 10 bar (or even higher) and the volumetric flow rate is up to 90,000l/h (liters/hour).

Claims (20)

1. A rotary displacement pump comprising:

(a) a stator (42);

(b) a rotor comprising a shaft portion (8) and radially projecting blades (12) having an undulating disc-type configuration;

(c) a scraper (110) comprising an engagement slot (112) having a predetermined radial height and a predetermined axial width, said engagement slot (112) being engaged with said projecting plate (12) of said rotor;

(d) the stator (42) comprising a first substantially cup-shaped stator component (44) and a second substantially cup-shaped stator component (46) and defining a circumferential wall around the radially projecting plate (12) of the rotor;

(e) the scraper (110) being arranged entirely within the stator (42), supported to be fixed in a circumferential direction and to allow reciprocating movement in a substantially axial direction;

(f) the stator (42) defines, with the scraper (110):

an inlet chamber (138) of the pump (2) having an inlet orifice (68),

an outlet chamber (142) of the pump (2) having an outlet orifice (70),

and a channel (140) extending from the inlet chamber (138) to the outlet chamber (142),

the scraper (110) forms a partition between the inlet chamber (138) and the outlet chamber (142), and the blade (12) of the rotor is rotatable through the inlet chamber (138), the channel, the outlet chamber (142), and the slot (112) of the scraper (110).

2. The pump of claim 1, wherein

The stator (42) forms a cylinder sleeve which is fixed in a housing (20) of the pump (2).

3. The pump of claim 1, wherein

The first stator member (44) and the second stator member (46) are made of a plastic material.

4. A pump according to claim 3, wherein

The first stator member (44) and the second stator member (46) are made of polyamide.

5. The pump of claim 2, wherein

The housing (20) is generally formed from a cylindrical tube (22) and two circular end plates (24, 26).

6. The pump of claim 2, wherein

The housing (20) is made primarily of stainless steel.

7. The pump of claim 1, wherein

The first stator member (44) and the second stator member (46) abut each other in a first abutment region (64) having a circular arc configuration and in a second abutment region (66) having a circular arc configuration;

the inlet aperture (68) of the stator (42) is formed by a first recess in a circumferential wall portion of the first stator member (44) and an opposing first recess in a circumferential wall portion of the second stator member (46);

the outlet aperture (70) of the stator is formed by a second recess in the circumferential wall portion of the first stator member (44) and an opposing second recess in the circumferential wall portion of the second stator member (46).

8. The pump of claim 7, comprising:

a first sealing member (72) disposed at the circumferential wall of the first stator member (44) proximate the first and second abutment regions (64, 66) and proximate the first and second recesses of the first stator member (44);

a second sealing member (74) disposed at the circumferential wall of the second stator member (46) proximate the first and second abutment regions (64, 66) and proximate the first and second recesses of the second stator member (46).

9. The pump of claim 8, wherein

The first sealing member (72) is a first O-ring disposed in a first groove (78) disposed on an outer surface in the circumferential wall portion of the first stator member (44);

and the second sealing member (74) is a second O-ring disposed in a second groove (78) disposed on an outer surface in the circumferential wall portion of the second stator member (46).

10. The pump of claim 7, comprising:

an integrally formed seal member (150) disposed in a groove disposed in the first and second abutment regions (64, 66) and in a groove (78) disposed in an outer surface of the circumferential wall in the first and second stator members (44, 46) proximate the first and second recesses in the first and second stator members (44, 46).

11. The pump of claim 7, comprising:

an integrally formed sealing member (150) disposed in the grooves provided in the first and second abutment regions (64, 66) and disposed in the grooves provided in the wall portions of the inlet and outlet apertures (68, 70).

12. The pump of claim 1, further comprising:

the guiding means (92) of the scraper (110) are secured within the stator (42) and provide the support for the scraper (110).

13. The pump of claim 12, wherein

The guide (92) has a generally concave configuration.

14. The pump of claim 12, wherein

The guide device (92) is fixed to the stator (42) by resting against at least part of its edge region in a groove (96, 98, 100, 102, 104) of the stator (42).

15. The pump of claim 14, wherein

The guide (92) is made of metal.

16. The pump of claim 12, wherein

The flight (110) is an integrally formed workpiece having a generally concave configuration,

the scraper (110) includes a first groove (120) having a predetermined depth and extending along a radially outer peripheral surface thereof,

the blade (110) further includes a second groove (124) and a third groove having a predetermined depth and extending in a radial direction along one leading edge surface and the other leading edge surface of the blade (110), respectively,

the three grooves (120, 124) are designed such that they receive a portion of the guide (92) and allow the reciprocating movement of the flight (110) in the generally axial direction.

17. The pump of claim 1, wherein

The scraper (110) is made of a plastic material.

18. The pump of claim 17, wherein

The blade (110) is made of polyamide.

19. The pump of claim 1, wherein

The rotor is supported by bearings (134) arranged beside the housing (20),

and the rotor extends into the stator (42) in a cantilevered manner.

20. The pump of claim 19, wherein

The pump (2) comprising a bearing portion (6) housing the bearing (134),

and the housing (20) is fastened to the support part (6).