Rotary displacement pump for pumping solids emulsions, especially liquid explosives

A rotary displacement pump of an undulatory disk type; with a pump housing (24) comprising a front end plate (56) and a rear end plate, the pump housing enclosing a stator (40, 48), a rotor (42), a scraper (44) and a scraper guide (46), a shaft (8) extending through at least the rear end plate; the stator including a generally semi-circular arc-formed first stator member (40) and a generally semi-circular arc-formed second stator member (48), the stator, the pump housing and the scraper together with the scraper guide defining an inlet and outlet chamber, wherein at least part of the end faces of the first and second stator members being situated in the outlet chamber are oblique so as to provide an obtuse-angled transition to the inner faces of the front end plate and the rear end plate.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit under 35 U.S.C. §371 of International Patent Application No. PCT/EP2010/063572, having an international filing date of Sep. 15, 2010, the content of which is incorporated herein by reference in its entirety.

FIELD

The present invention relates to a rotary displacement pump for pumping solids emulsions, especially liquid explosives.

BACKGROUND

From the EP 1 807 624 B1, a rotary displacement pump is known which allows for pumping flowable, relatively viscose materials in the food stuff industry, the chemical and biochemical industry, the medical industry and the cosmetic industry. Examples of materials that can be pumped by such rotary displacement pump are yoghurt, soup, sauce, mayonnaise, fruit juice, cheese material, chocolate, paint, cosmetic cream, and lipstick material.

Now there is a need for pumping solids emulsions, especially liquid explosives. Such liquid explosives are for example used in the mining industry in the field of tunneling and operation of quarry where such liquid explosives have to be pumped in cavities and channels in the rocks where they are ignited to explode in a controlled fashion.

The rotary displacement pump disclosed in the EP 1 807 624 B1 is not suitable for pumping such solids emulsions. When pumping such solids emulsions with the displacement rotary pump, the solids emulsions collect, build up and pack in certain regions of the pump which increases the friction, builds up additional pressure and heats up the pump. This results in a loss of efficiency or even a total outage of the pump. When pumping liquid explosives comprising small spherical components also referred to as prill it is this prill that collects, builts up and packs in many places of that pump, which in addition to the drawbacks as mentioned above, is dangerous to men and environment. In the worst case, the whole rotary displacement pump can explode, when the temperature within the pump rises above a critical point.

Currently, the pumps used for pumping such solids emulsions and liquid explosives are of bigger size and more complex design which makes their use in connection with solids emulsions and liquid explosives inconvenient and expensive and which limits the applications to situations where enough space is available for such bigger pumps.

SUMMARY

It is therefore an object of the invention to provide a rotary displacement pump of the “protruding web of rotor engaging in an engagement slot of scraper”-type allowing for a small pump size and being capable of pumping solids emulsions especially liquid explosives in an efficient and safe manner.

This object is attained by a rotary displacement pump for pumping solids emulsions, especially liquid explosives as defined in claim1.

Such rotary displacement pumps comprises a stator; a rotor configured to be driven by a shaft, the rotor including a shaft portion and a radially protruding web having a configuration of an undulatory disk type; a scraper having an engagement slot of predetermined radial height and predetermined axial width, the engagement slot engaging the protruding web of the rotor; the scraper being supported by a scraper guide so as to be retained in circumferential direction and to allow a reciprocating movement in a substantially axial direction; a pump housing comprising a front end plate and a rear end plate, the pump housing enclosing the stator, the rotor, the scraper and the scraper guide; the shaft extending through at least the rear end plate; the stator including a generally semi-circular arc-formed first stator member and a generally semi-circular arc-formed second stator member, the first and second stator members abutting to each other laterally along a radially outer abutment portion so as to form a stator channel through which the radially protruding web of the rotor runs and to define an enclosure that encircles a generally semi-circular arc-formed portion of the radially protruding web of the rotor; the stator, the pump housing and the scraper together with the scraper guide defining an inlet chamber and an outlet chamber, the scraper together with the scraper guide forming a partition between the inlet chamber and the outlet chamber, the inlet and outlet chambers being provided with respective inlet and outlet ports; the stator channel extending from the inlet chamber to the outlet chamber, the web of the rotor being rotatable through the inlet chamber, the stator channel, the outlet chamber and the slot of the scraper, wherein at least part of the end faces of the first and second stator members being situated in the outlet chamber are oblique so as to provide an obtuse-angled transition to the inner faces of the front end plate and the rear end plate.

With such a rotary displacement pump, solids emulsions, and especially liquid explosives can be pumped efficiently and safely. By the obtuse-angled transition of at least part of the end faces of the first and second stator members to the inner faces of the front and rear end plates, the material build up, and especially the prill build up along edges and in grooves is minimized, thereby providing for an efficient and safe operation of the rotary displacement pump when pumping solids emulsions and especially liquid explosives. It has been discovered by the inventors that it is mostly the prill that builds up and packs within the pump housing and in particular within the outlet chamber, and such prill, in addition to packing the pump housing and in particular the outlet chamber, has a disadvantageous abrasive effect.

The inventors of the present rotary displacement pump have made countless different modifications to different features of rotary displacement pumps until finding out that by the rotary displacement pump, as defined in claim1, an efficient and safe pumping of solids emulsions, and especially liquid explosives can be attained.

By the outlet chamber which is confined by the end faces of the first and second stator members providing an obtuse-angle transition to the inner faces of the front and rear end plates, by the pump housing, by the scraper and the scraper guide, the material built up and the packing of material can be significantly reduced which provides for improved material flow characteristics and, consequently, for an efficient and safe operation.

According to a first embodiment of the invention, the obtuse-angle between the end faces of the first and second stator members and the inner faces of the front end plate and the rear end plate is 120 to 160°, particularly 140 to 160°. These angles have been proven to provide for a particularly good and smooth material flow.

According to a further embodiment of the invention the shaft extends through both the front and rear end plates, which are provided with central openings for this purpose, and generally tube-shaped front and rear seal housing elements are provided being positioned in the recesses of the first and second stator elements.

These housing elements are stationary and encircle the rotating shaft/shaft sleeve elements.

According to a further embodiment of the invention, these seal housing elements confine the inlet and outlet chambers in a direction towards the shaft therefore provide part of the boundary of the inlet and outlet chambers.

According to a further embodiment of the invention, the seal housing elements are provided with at least one slot in order to reduce the pressure within the inlet and outlet chambers and in order to relieve material build up. The pumped solids emulsions will get through such slot into the interspace between the seal housing elements and the shaft/shaft sleeve elements, and material built up above the seal housing elements can be minimized.

According to a further embodiment of the invention, front and rear shaft sleeves attach to the rotor, wherein the front and rear shaft sleeves are situated within the seal housing elements, and wherein sealing elements are provided between the rotating front and rear shaft sleeves and the stationary seal housing elements.

Such sealing elements provide for a sealing between the rotating front and rear shaft sleeves and the stationary seal housing elements. However, these sealing elements are not totally tight, but allow for a pressure compensation, and a certain amount of the pumped solids emulsions can pass through the sealing elements in a forward direction out of the front end plate and in a rearward direction out of the rear end plate and can leave the pump housing that way.

According to a very compact embodiment of the invention, the sealing elements are provided at the inner side of the seal housing elements.

According to a further embodiment of the invention, the sealing elements are formed as three lip sealing rings with two interposed support rings. The two sealing rings that are situated closest to the rotor provide for a sealing to the outside, and the outermost sealing ring provides for a sealing from outside to inside.

According to a further embodiment of the invention, the generally tube-shaped front seal housing element and the generally tube-shaped rear housing element are of identical shape and size.

According to a further embodiment of the invention, the front and rear shaft sleeves are also of identical shape and size.

By mirroring the design of the front and rear housing elements and, preferably, also of the front and rear shaft sleeves a part commonality is attained which helps to save costs and provides a means of pressure relief at both ends of the shaft.

According to a further embodiment of the invention, the tip of the shaft or the front shaft sleeve and/or a front locking element that secures the front shaft sleeve to the shaft protrudes out of that front end plate, which is provided with a central opening.

It has been discovered by the inventors, that by such embodiment material built up is further mitigated and a pressure relief through the front sealing element in a forward direction can be attained. It has further been discovered that by such embodiment the drawback of a material build up and packing of material between a bushing assembly and the cover which happened when the front cover end of the shaft was closed and supported by a bushing can reliably be avoided. According to a further effect of this embodiment a certain degree of load support is achieved in addition.

According to a further embodiment of the invention, a security cover element is provided covering the tip of the shaft or the front shaft sleeve and/or the front locking element, wherein this security cover element has evacuation apertures, particularly radially oriented evacuation apertures in order to allow for the solids emulsions to pass through. By the provision of such security cover element injuries caused by the rotating shaft tip can be avoided. The solids emulsion can pass through the evacuation apertures which further helps avoiding material built up in the inside of the pump housing.

According to a further embodiment of the invention a recessed spacer element having evacuation apertures, in particular radially-oriented evacuation apertures, is provided behind the rear end plate. The evacuation apertures allow for the solids emulsion passing through which further mitigates material build up and provides for an additional pressure relief through the rear sealing element in a rearward direction.

According to a further embodiment of the invention, the evacuation apertures are closed by means of grating elements, in particular by means of a grating security ring. Thereby a discharge of solids emulsion can be attained, wherein at the same time injuries by people unintentionally putting their fingers through the apertures and touching the rotating shaft or shaft sleeves can be avoided.

According to a further embodiment of the invention, the scraper has the general form of a plate, particularly a rectangular plate, with the engagement slot formed therein. Furthermore, the width of the scraper can correspond to 65 to 75%, particularly to 68 to 72% of the width of the inlet and outlet chambers, measured from the front end plate to the rear end plate of the pump housing, so as to provide, in the extreme axial positions of the scraper, for sufficient distance between the side faces of the scraper and the front and rear end plates of the pump housing.

The inventors have found that by a scraper of such reduced width material built up in particular in between the side faces of the scraper and the front and rear end plates of the pump housing, in corner areas as well as in mating cavities in the pump housing can be significantly reduced which contributes to a safe and efficient operation of the pump.

According to a further embodiment of the invention, the scraper has the general form of plate, particularly a rectangular plate, with the engagement slot formed therein. The side faces of the scraper can be oblique with respect to an axial plane, with the rear face of the scraper oriented towards the outlet chamber having a smaller surface area than the front face of the scraper oriented towards the inlet chamber. By this feature the effect of packing solids emulsions, in particular into the space between the side faces of the scraper and the facing portions of the front and rear end plates of the pump housing, into corner areas of the outlet chamber and into mating cavities in the pump housing can be considerably reduced. This embodiment further contributes to a safe and efficient operation of the pump.

According to a further embodiment of the invention, the angle between the side faces of the scraper and the axial plane is in the range of 20 to 60 degrees, particularly in the range of 30 to 40 degrees. These angles have been found to be particularly advantageous.

According to a further embodiment of the invention, the scraper guide has a form of a recessed plate or cartridge, with the width of the recess being such that the engagement slot of the scraper in its extreme axial positions lies within this recess, thereby providing a compact and reliable construction of the scraper and scraper guide.

According to a further embodiment of the invention, the scraper guide can be provided with limit stops defining the extreme axial positions of the scraper. By the provision of such limit stops the limits of the movement of the scraper can be defined precisely therefore preventing misfunction.

According to a further embodiment of the invention, the scraper guide is supported within the pump housing between the front end and rear end plates. For this purpose at least one of the front and rear end plates can be provided with a mating cavity in order to support the scraper guide. By these features the scraper guide can be maintained in its optimum position reliably and permanently.

According to a further embodiment of the invention, the scraper has a radially outer guiding groove that engages with a corresponding guiding track of the scraper guide and a radially inner guiding groove engaging with corresponding circumferential portions of the seal housing elements. Thus, the scraper can be retained in a circumferential direction and allows for a reciprocating movement in a substantially axial direction. This configuration is particularly compact and stable and only requires a minimum number of parts involved.

According to a further embodiment of the invention, the material of the scraper is chosen with a melting temperature below the critical temperature of the pumped product. If the temperature within the pump housing rises due to dead heading, dry running, mechanical binding or another cause, the engagement slot in the scraper that mates with the rotor will deform and enlarge, thus reducing friction and preventing additional pressure and heat built up. This embodiment contributes for further safety of the pump operation.

The present invention also relates to the use of a pump, as described and defined above, for pumping solids emulsions of any kind and in particular for pumping liquid explosives. As described above, the inventors have found out that by a pump having a design as defined in the appended claims, such difficult and dangerous materials can be pumped safely and efficiently.

The invention will now be described in greater detail referring to the embodiments described in the following and shown in the accompanying drawings.

DETAILED DESCRIPTION

The terms “front” and “back/rear” are to be understood in the forthcoming figures with respect to the axis of the shaft8, the terms “left” and “right” are to be under-stood in the forthcoming figures with respect to the axis of the shaft8, when seen from the back (substantially right-hand inFIG. 1) to the front (substantially left-hand inFIG. 1) of the shaft8, such that the parts of the pump that lie, with respect to the shaft8, on the closer side to the viewer inFIG. 1are positioned “left” and the parts of the pump that lie, with respect to the shaft8, on the farther side from the viewer inFIG. 1are positioned “right”.

FIG. 1shows an entire rotary displacement pump2comprising a pump part4or pump proper4and a support part6.

At the right-hand side ofFIG. 1, an end portion of a shaft8protrudes from the support part6. A drive motor, not shown, typically an electric motor serves to apply torque to the shaft8, either by being directly or through a coupling coupled to the shaft8or for example through a gear or a pulley etc. The support part6comprises a support part housing10in which appropriate roller bearings (not shown) for the shaft8can be provided.

The support part housing10has a substantially cylindrical shape, and the front end of the support part housing10is encircled and fixed by a mounting frame12that has a lower mounting plate in order to fix the entire rotary displacement pump2to an appropriate base. At the left and right sides of the frame part of the mounting frame12there are provided mounting pins14protruding out of the front side of the mounting frame12in a forward direction in order to engage with corresponding holes in the spacer ring22and the tubular cylindrical body34(to be described in further detail later) and to join the support part6and the pump part4firmly together. The middle to front portion of the shaft8is provided with axially extending recesses that engage with corresponding protrusions of the disk member42(described in further detail later), and, if appropriate, with other rotating parts of the pump part4. The tip of the shaft8is tapering.

A disk member42is keyed to the shaft8and rotates with the shaft8. In the following, the disk member42will be referred to as “disk42”. The shaft8and disk42are part of a rotor. The disk42comprises a radially protruding web having an axial thickness and predetermined outer diameter. The web has a rear surface and a front surface. If one follows, for example with a fingertip the front surface, along the circle line of the outer diameter, the fingertip will describe a curved sinus-type line seen in radial view (not necessarily in the strict mathematical sense), undulating with respect to a middle plane intersecting the axis of the shaft8at a right angle. Along a 360° circle there are two full periods of the sine curve, i.e. the first time from completely left-hand inFIG. 1to completely right-hand inFIG. 1and back. The same description as made with respect to the front face applies to the rear face as well. For simplicity, this undulating form of the web of the disk42is not depicted in the figures.

The pump proper4, in the following referred to simply as “pump4”, comprises a pump housing24having the following the main parts: a tubular cylindrical body34provided at its rear end with a circular, rear end plate (not visible inFIG. 1), a circular front end plate56, an inlet pipe socket/inlet port26provided with an inlet port flange28, and an outlet pipe socket/outlet port30provided with an outlet port flange32. The inlet and outlet ports26,30are welded to the tubular cylindrical body34.

The axis of the inlet and outlet ports26and30intersect at 90°. Accordingly, the tubular cylindrical body34has two openings corresponding to the diameter of the inlet and outlet ports26and30.

The body22, the end plates and the inlet and outlet ports26,30consist of stainless steel.

A stator lines the lower half of the inside of the housing24. The stator consists of a generally semi-circular arc-formed rear stator member40and of a generally semi-circular arc-formed front stator member48, that can be formed separately as in theFIG. 1, or integrally with the front end plate and, respectively the rear end plate. The stator elements can be formed as liner elements fixed in the pump housing24. They can be made of plastics material, particularly polyamide.

Taking reference toFIG. 2, the front stator member48abuts with its outer surface (the term outer is to be understood with respect to the disk42) against the ring-formed inner face90of the front end plate56. In a radial sectional cut, the front stator member48has the profile of an “L”/a reversed “L” with the radially oriented portion of the profile forming an radial wall70for the web42and with the axially-oriented portion of the profile forming a circumferential wall68for the web42. Accordingly, the inner end (the term “inner” is to be understood opposite to the term “outer”, see above) of the circumferential wall68forms a lateral abutment face74that abuts in the mounted state to the opposite lateral abutment face of the rear stator member40.

The face of the circumferential wall68that is oriented towards the shaft axis forms a stator channel bottom face76and the inner face of the radial wall70forms a lateral stator channel face78.

Appropriate sealing means sealing the outer face72of the front stator element48to the lower half of the inside of the tubular cylindrical body34can be provided (not shown).

Following a central opening92of the rear end plate56there is a recess provided in the front stator element48so that the shaft8can extend through both the central opening92and the central recess.

The upper left end face of the generally semi-circular arc48, which is designated with reference numeral80inFIG. 2, is straight and extends horizontally. It forms the inlet chamber bottom80.

The upper right end face of the generally semi-circular arc48, comprises a straight, horizontal end face of the circumferential wall68forming a straight outlet chamber bottom part84and a oblique end face of the radial wall70forming an oblique transition portion82of the outlet chamber to the ring-formed inner face90of the front end plate56.

The same description as made with respect to the front stator element48applies in an analogous manner to the rear stator element40. Generally speaking, the rear stator member40is a mirror-image to the front stator member48, and the rear stator member40butts with its outer surface to the ring-formed inner surface of the rear end plate of the pump housing24.

Taking reference toFIG. 1again, there are provided, in the upper part of the inside of the pump housing24, an inlet chamber adjacent to the inlet port26and an outlet chamber adjacent to the outlet port30. The inlet chamber is provided in the upper left quadrant of the inside of the pump housing24that is located closer to the viewer ofFIG. 1and the outlet chamber is provided in the upper right quadrant of the inside of the pump housing24that is located farther from the viewer ofFIG. 1.

When the parts of the pump proper4are assembled, the inlet chamber is confined by the inlet chamber bottoms80of the stator elements40and48, by the parts of the front and rear seal housings50and36lying in the upper left quadrant of the inside of the pump housing24, by the left sides of the scraper44and the scraper guide46and by the inner face of the upper left quadrant of the tubular cylindrical body34.

Likewise, when the parts of the pump proper4are assembled, the outlet chamber is confined by the straight outlet chamber bottoms84and the oblique transition portions82of the stator elements40and48, by the parts of the front and rear seal housings50and36lying in the upper right quadrant of the inside of the pump housing24, by the right sides of the scraper44and the scraper guide46and by the inner face of the upper right quadrant of the tubular cylindrical body34.

The hub of the disk42is clamped by means of a locking screw54in axial direction against the rear shaft sleeve38and against the front shaft sleeve52having a locking nut. The rotating rear shaft sleeve38is, when the parts of the pump proper4are assembled, situated inside the rear seal housing36, and, likewise, the rotating front shaft sleeve52is situated within the front seal housing50.

Sealing means are provided at the inner face of the shaft sleeves38and50. In the most simple form such sealing means can be provided in the form of a sealing ring or sealing lip. Such sealing means can also be provided in the form of three spaced-apart lip sealing rings with two interposed support rings112as can be seen in the embodiment of the rotary displacement pump2inFIG. 5.

As can be seen inFIG. 1, both the rear seal housing36and the front seal housing50are of identical shape and size, and both are provided with slots, particularly circumferentially extending slots that allow for pressure compensation between the inside and the outside of the pump housing24, that facilitate the cleaning and that allow for pumped material to enter in between the seal housings36and50and the shaft sleeves38and52and to and through the sea lings that are provided therebetween to an outside of the pump housing24.

Furthermore, the shape and size of the rear shaft sleeve38and the front shaft sleeve52(with the exception of the locking nut) are identical in the embodiment ofFIG. 1.

Thereby the parts variety will be reduced which allows for corresponding sealing arrangements in both the front and rear directions, as seen from the disk42, which reduces the costs.

The scraper44has generally the configuration of a rectangular plate, but having an engagement slot into which the web of the disk42engages.

The scraper can be a unitary work piece, particularly made of polyamide.

Referring now toFIGS. 3 and 4, curved transitions98are provided between the narrowest portion of the engagement slot96and the outlet chamber-facing surface100that can be seen inFIGS. 3 and 4as well as the inlet chamber-facing surface that can be seen inFIG. 1.

The axial dimension of the engagement slot96at its smallest portion is just a little wider than the axial dimension of the web of the disk42, so that the engagement slot96can be placed over the web, the scraper44straddling the web. The curved transitions98take into account the curved or undulatory configuration of the web as contrasted to a plane configuration.

The scraper44according to the embodiment ofFIG. 3as well as the scraper44according to the embodiment ofFIG. 4have a reduced width, as seen in the axial dimension inFIG. 1from its front side end102(left-hand side inFIGS. 3 and 4) to its rear side end102(right-hand side inFIGS. 3 and 4). In the embodiment ofFIGS. 3 and 4the width of the scraper44corresponds to 68 to 72%, particularly 71% of the distance between the inner faces of the front end plate56to the rear end plate.

The scrapers44of the embodiment of bothFIGS. 3 and 4have an upper guiding groove104extending in an axial direction along the radially outer surface, this upper guiding groove104is extending between left and right upper guiding walls having a higher height in the lateral side portions and a reduced height in the middle portion. A corresponding guiding rail of the scraper guide46(not shown) engages into the upper guiding groove104.

Likewise, the scrapers44of the embodiments of bothFIGS. 3 and 4have a lower guiding groove106of a rounded convex shape, this lower guiding groove106engaging with a corresponding circumferential portion of the seal housings36and50.

By the guiding grooves104and106of the scraper44and by the corresponding guiding rail of the scraper guide46(not shown) and the corresponding circumferential portions of the seal housing elements36and50, the scraper44is retained in the circumferential direction and a reciprocating movement in a substantially axial direction is made possible.

Furthermore, limit stops defining the extreme axial positions of the scraper44can be provided, particularly at the scraper guide46. Moreover, the scraper guide46having in the embodiment ofFIG. 1the form of the partial cartridge has an outlet chamber oriented-surface against which the inlet chamber oriented larger surface of the scraper44butts and thus secures, in addition, the scraper44against a movement in circumferential direction.

The lateral side faces102of the scraper44in both embodiments ofFIGS. 3 and 4are oblique with respect to an axial plane, wherein the angle to an axial plane is in the range of 20 to 60 degrees, in the embodiment ofFIG. 3it is 50 degrees and in the embodiment ofFIG. 4it is 35 degrees.

In the scraper44ofFIG. 3, the oblique side faces102form a plane extending over the whole radial height of the scraper44, wherein in the scraper44ofFIG. 4the side faces102are surrounded in a radially outward direction by upper side face walls108and in a radially inward direction by lower side face walls110.

By the reduced width of the scraper44and by the oblique side faces102, the effect of packing material into corner areas of the outlet chamber, particularly between the side faces102and the inner faces of the front and rear end plates is significantly reduced, which contributes to a good material flow and thus an efficient and reliable operation of the pump.

The scraper guide46is firmly mounted in the pump housing24, in particular between the front end plate56and the rear end plate.

Referring again toFIG. 2, a substantially cylindrical supporting cavity94is formed in the upper portion of the inner side of the front end plate56above the central opening92, this supporting cavity94supports and secures the scraper guide46when the parts of the pump proper4are assembled. Likewise a supporting cavity can be provided in the rear end plate (shown inFIG. 5).

Referring again toFIG. 1, between the front face of the support part housing10/mounting frame12and the rear end plate of the pump housing24there is provided, from back to front, a shaft sleeve16, a rear security ring18, a retainer ring20and a spacer ring22with lateral evacuation apertures.

In the mounted state of the pump2that can be seen inFIG. 5material coming out of the pump housing24in a rearward direction, particularly through the sealing between the rear seal housing36and the rear shaft sleeve38can run out of these lateral evacuation apertures, wherein at the same time the grating-like rear security ring18prevents users from unintentionally touching the rotating shaft8/shaft sleeve16.

InFIG. 5it can further be seen that the shaft sleeves16and20attach to each other, both of them are firmly secured to the shaft8.

Further, the locking screw54extends through the front shaft sleeve52with the locking nut and is fixed in the central opening of the shaft8by means of threads (not shown) provided at the locking screw54and the central opening of the shaft8. By this configuration, the front shaft sleeve52, the disk42, the rear shaft sleeve38and the further shaft sleeve16are fixed firmly to the shaft8such that they rotate together with the shaft8.

As can further be seen inFIG. 5, the front end of the shaft configuration, i.e. the front end of the front shaft sleeve52with the locking nut and the locking screw54, protrudes out of the central opening in the front end plate56. Material coming out of the pump housing24in a forward direction, particularly between the rotating front shaft sleeve52and the stationary front seal housing50and the sealing112provided therebetween can leave the pump2through the radial evacuation apertures in a security cover64that is placed before the central opening of the front end plate56and the front shaft sleeve52as well as the locking screw54protruding out of that central opening. The diameter of the security cover64is somewhat smaller than the diameter of the front end plate56.

As with the radial evacuation apertures in the spacer ring22the radial evacuation apertures in the security cover64are closed from unintentional access by a user in a radial direction by means of a security grating ring62. The front security ring62corresponds in shape and size to the rear security ring18which further helps to reduce the number of parts involved and thus to reduce costs.

Furthermore, mounting pins58and front cover nuts66are provided in order to firmly and safely fix the security cover64to the front end plate56and the front end plate56to the tubular cylindrical body34.

InFIG. 5the rear end plate57that is formed integral with the tubular cylindrical body34can well be seen. Furthermore, it can be seen that the web of the disk42engages with the engagement slot of the scraper44. In the sectional cut of the upper left quadrant ofFIG. 5the portions of the parts lying in this quadrant and in particular the inlet port26and the inlet port flange28are omitted. Not visible inFIG. 5are the front and rear stator elements40and48.

InFIG. 5, the left-hand side of the cartridge-like scraper guide46is omitted and thus the inlet chamber facing-surface of the scraper44and part of the outlet chamber can be seen in axial direction before and behind the scraper44.

Furthermore, the dimension of the outlet chamber in the axial direction can be seen, from the front bottom (in axial direction) of the supporting cavity in the front end plate56to the rear bottom (in axial direction) of the supporting cavity in the rear end plate57of the tubular cylindrical body34.

By the rotary displacement pump2as described with respect toFIGS. 1 to 5, which consist of a relatively small number of parts making it cheap and easy to manufacture, solids emulsions of any kind and particularly liquid explosives can be pumped efficiently and safely.

List of Reference Numerals

10support part housing

18rear security ring

36rear seal housing

50front seal housing

52front shaft sleeve with locking nut

56front end plate

57rear end plate

66front cover nuts

76stator channel bottom face

78lateral stator channel face

80inlet chamber bottom

82oblique transition portion of outlet chamber

84straight outlet chamber bottom

90ring-formed inner face

102oblique side faces

108upper side face walls

110lower side face walls