EP0617753B1 - Rotary piston pump - Google Patents

Abstract

The present invention relates to a rotary piston pump for conveying and/or metering liquid or pourable media. It consists of a pump casing (2) with a cylinder chamber (4) having a cylindrical inner periphery (6) into which open at least one inlet (8) and at least out outlet (10), and a rotary piston (20) rotating inside the cylinder chamber (4) which, together with at least one region of its outer peripheral surface (22) forms a seal with the inner peripheral surface (6) of the cylinder chamber (4) and is separated in regions from the inner peripheral surface (6) by a radial stroke distance. When the rotary piston rotates (arrow 70), an expanding working chamber (24) is formed in the region of the inlet (8) to draw the medium in and, on further rotation, contracts again in the region of the outlet to force the medium out. The working chamber (24) concerned is limited, at least during its increase or decrease in volume, by at least one separating slide (26) in front of the inlet (8) or behind the outlet (10) viewed in the direction of rotation. Said slide is moved to and fro (arrow 32) in the pump casing (2), as the rotary piston (20) rotates, in a substantially radial direction to the axis of rotation (34) in such a way that it forms a seal with the outer peripheral surface (22) of the rotary piston (20). The separating slide (26) is forcibly moved by means of a drive device (30) synchronised with the rotary piston (20).

Description

The present invention relates to a rotary piston pump for conveying flowable or free-flowing, in particular liquid, pasty or granular media, consisting of a pump housing with a cylinder space having a cylindrical inner circumferential surface, into which at least one inlet and at least one outlet open, and from one inside the Cylinder space around a coaxially rotating axis of rotation-driven rotary piston with an outer peripheral surface, the radial distance to the axis of rotation changes over the circumference such that the rotary piston with at least a portion of the outer peripheral surface cooperates sealingly with the inner peripheral surface of the cylinder space and in regions from the inner peripheral surface by one Axis of rotation is spaced radially from the stroke, so that when the rotary piston rotates in the area of the inlet for sucking in the medium to be conveyed, the volume increases beitskammer is formed, which then continues to decrease in volume in the area of the outlet for displacing the medium after continued rotation, the respective working chamber at least during its volume increase or reduction of at least one seen in the direction of rotation in front of the inlet or behind the outlet arranged separating slide is limited, which is pushed back and forth in the pump housing upon rotation of the rotary piston in a substantially radial direction to the axis of rotation so that it with the Surface facing the rotary piston always cooperates sealingly with the outer peripheral surface of the rotary piston, the displacement of the separating slide being carried out inevitably by means of a drive device synchronized with the rotary piston.

For general-purpose rotary piston pumps, reference is made, for example, to "Lueger, Lexikon der Technik", DVA-Stuttgart, volume 7 1965, page 218, image 7 and volume 16 1970, pages 243, 244, image 6. Each of these known pumps has an inlet and an outlet directly adjacent to it opposite to the direction of rotation and spaced in the direction of rotation by a circumferential "delivery path". The rotary piston has a cylindrical outer circumference and is connected eccentrically to a shaft coaxial to the cylinder space in such a way that at a point on its outer circumference it touches the inner circumferential surface of the cylinder space in a linear manner, as a result of which working chambers which vary in volume are formed during its rotation. A separating slide is arranged between the inlet and the outlet for the separation between the suction side and the pressure side, which separates the working chamber which enlarges when the rotary piston rotates in the area of the inlet from the working chamber which shrinks in the area of the outlet. This means that the slide valve delimits the working chambers in front of the inlet and behind the outlet. The isolating slide is connected to the outer circumference of the rotary piston by a spring pressed and therefore moved back and forth immediately when the piston rotates. This is disadvantageous because there is a high level of friction between the slide valve and the rotary piston combined with a correspondingly high level of wear. This disadvantage can only be reduced by lubrication, but this is only unproblematic if lubrication can take place by the medium to be conveyed itself, ie if the medium is, for example, oil. However, if another medium is to be pumped, lubrication is at best possible, in order not to "contaminate" the medium with the lubricant, ie to change it chemically. The known pumps are therefore not or only partially suitable, in particular for conveying foodstuffs, such as, for example, dairy products. The spring loading of the isolating slide described is also disadvantageous insofar as resonance phenomena could occur under certain operating conditions, which could result in a "fluttering" of the isolating slide and thus undesired leaks between the suction and pressure sides. Therefore, a spring must always be tuned in such a way that the natural vibration of the "spring / isolating slide system" is high compared to the rotation frequency. As a rule, this can only be achieved satisfactorily if a strong spring (high spring force) is used, but this disadvantageously increases the friction between the separating slide and the rotary piston.

DE-U-69 31 657 describes a rotary pump which has a rotary piston which is polygonal in cross section and which is rotatably mounted in a cylindrical bore in a housing. Each between an outlet pipe and a suction pipe following this in the direction of rotation a slide-like separating element separating these lines from one another is arranged, each of these separating elements being displaceably guided in the piston housing and resting under spring pressure on the circumference of the piston. For this purpose, a spring element is provided which is designed as an annular spring and exerts spring forces directed radially towards the center on the separating members. It is clear from this that this known rotary pump essentially corresponds to the prior art already recognized above, because the slide-like separating members are moved directly by the rotary piston due to their abutment on the rotary piston. There are therefore essentially the same disadvantages.

French publication FR-A-2 464 389 describes a hydraulic machine which can be used both as a pump and as a motor. Here too, gate valves are moved directly by their abutment on cam surfaces of the housing.

EP-A-0 065 591 relates to a rotary piston machine of the generic type described at the outset, which can be used in particular as a motor. It is known per se to force the slide via a drive device, for which purpose the rotary piston has lateral guide grooves in which guide elements of the slide are led. However, the sealing problem is particularly addressed in this known machine, for which it is disclosed, among other things, that the separating slide always rests on the piston via sealing strips, and that the slide is even to be pressed against the piston by gas pressure and / or spring pressure .

Furthermore, rotary piston machines (in particular steam engines) are also known per se from some quite old documents, in which a hermetic seal of the respective working chamber is important with regard to a “slide valve drive device”.

Thus, in the (steam) machine described in US Pat. No. 996,272, a sliding abutment on a rotary piston is clearly disclosed ("sliding abutment").

The same applies correspondingly to the steam engine known from US-A-935 489, in which a slide is also disclosed as a "sliding abutment", ie as a "displaceable contact element".

Finally, US-A-892 351 also describes a steam engine with such an abutment element (“sliding abutment”), which is even equipped with an additional seal.

The invention has for its object to improve the generic rotary piston pump so that it works on the one hand with little wear and noise and on the other hand not only for the delivery of almost any media, but also for the exact metering of the amount or volume of the medium conveyed is suitable.

According to the invention, this is achieved in that a metering device is provided for varying the stroke conveying volume of the respective medium conveyed in one of the working chambers. In this embodiment according to the invention, the rotary piston pump is therefore practical to be referred to as a "metering pump". Flowable or free-flowing media, in particular granular, powdery media, can be metered very precisely. This will be discussed in more detail in the following description of the figures.

Because the displacement of the separating slide is forcibly carried out in a manner known per se by means of a drive device synchronized with the rotary piston, it is advantageously possible in a preferred embodiment of the invention to guide the or each separating slide in such a way that it is always in every rotational position of the Piston, is spaced from the outer circumferential surface of the rotary piston over a narrow, defined sealing gap, so that friction in this area advantageously with all disadvantageous consequences can be avoided entirely. Lubrication can therefore also be dispensed with in this area, so that contamination of the medium being conveyed with lubricant is also completely ruled out. The pump according to the invention is therefore particularly suitable for foodstuffs, such as dairy products in particular, especially since, due to the basic structure, the medium is also conveyed almost without pressure ("entrainment" via the working chambers), so that mechanically sensitive media, such as emulsions, are conveyed very gently ; a mechanical "smashing" of the emulsion (eg milk, cream and the like), as it could occur, for example, in the case of non-generic vane or centrifugal pumps, is advantageously avoided.

It is particularly advantageous if the drive device is designed as a cam drive which, in a preferred embodiment, has at least one cam track (control cam track) which rotates synchronously and coaxially with the rotary piston and is designed as an open groove in the direction of the axis of rotation, in each of which one with the separating slide over a motion transmission link connected cam is guided. The circumferential course of the cam track is precisely adapted to the course of the outer circumferential surface of the rotary piston, so that the separating slide during the rotation of the rotary piston by radial reciprocating movement with its surface facing the piston exactly follows the course of the piston outer circumference. Advantageously, the above-mentioned resonance phenomena are also avoided by the "positive guidance" according to the invention, so that an optimal sealing effect is always maintained in the region of the respective slide valve under all operating conditions (e.g. at any speed).

In a particularly advantageous embodiment of the invention, there are several, in particular, within the pump housing formed three, evenly distributed over the circumference of the cylinder part pumps each with an inlet and an outlet. In each case, an inlet of one of the sub-pumps is arranged at a short distance adjacent to an outlet of the sub-pump which is adjacent (upstream in the direction of rotation) and a separating slide is arranged between the outlet of one sub-pump and the inlet of the other sub-pump. All existing separating slides are then driven by the same drive device, in that a corresponding cam is guided in each case in the same cam track for each separating slide.

Further advantageous design features of the invention are contained in the subclaims and the following description.

Fig. 1

eine axiale Vorderansicht einer Rotationskolbenpumpe in einer ersten Ausführungsform,

Fig. 2

einen Halb-Axialschnitt längs der Linie II-II in Fig. 1,

Fig. 3

eine axiale Vorderansicht in Pfeilrichtung III gemäß Fig. 2 unter Weglassung eines Gehäusedekkels,

Fig. 4

eine axiale Rückansicht in Pfeilrichtung IV gemäß Fig. 2 unter teilweiser Weglassung eines Gehäusedeckels,

Fig. 5

einen Teil-Querschnitt längs der Linie V-V in Fig. 2,

Fig. 6

eine Draufsicht einer Einzelheit in Pfeilrichtung VI gemäß Fig. 2,

Fig. 7

einen Teilschnitt längs der Linie VII-VII in Fig. 3,

Fig. 8

einen Teil-Axialschnitt einer zweiten Ausführungsform einer Rotationskolbenpumpe,

Fig. 9

eine Stirnansicht in Pfeilrichtung IX gemäß Fig. 8 unter Weglassung eines Gehäusedeckels,

Fig. 10

einen Halb-Querschnitt längs der Linie X-X in Fig. 8,

Fig. 11

einen Teilschnitt längs der Linie XI-XI in Fig. 9,

Fig. 12

eine axiale Vorderansicht analog zu Fig. 1 in einer erfindungsgemäßen Ausführungsform der Rotationskolbenpumpe,

Fig. 13

einen Teil-Axialschnitt längs der Linie XIII-XIII in Fig. 12,

Fig. 14

eine axiale Vorderansicht wie in Fig. 12, d.h. in Pfeilrichtung XIV gemäß Fig. 13, allerdings unter Weglassung eines vorderen Gehäusedeckels, und

Fig. 15

eine Ansicht analog zu Fig. 14, jedoch in einer weiteren Ausgestaltung der Erfindung.

The invention will be explained in more detail below with reference to preferred exemplary embodiments illustrated in the drawing. It should be noted that the invention, that is to say the metering device, is only implemented in the embodiments according to FIGS. 12 to 15, while FIGS. 1 to 11 serve to explain advantageous design features and configurations. Show it:

Fig. 1

an axial front view of a rotary piston pump in a first embodiment,

Fig. 2

a half-axial section along the line II-II in Fig. 1,

Fig. 3

3 shows an axial front view in the direction of arrow III according to FIG. 2 with the omission of a housing cover,

Fig. 4

3 shows an axial rear view in the direction of arrow IV according to FIG. 2, with partial omission of a housing cover,

Fig. 5

3 shows a partial cross section along the line VV in FIG. 2,

Fig. 6

2 shows a plan view of a detail in the direction of arrow VI according to FIG. 2,

Fig. 7

a partial section along the line VII-VII in Fig. 3,

Fig. 8

2 shows a partial axial section of a second embodiment of a rotary piston pump,

Fig. 9

8 shows an end view in the direction of arrow IX according to FIG. 8 with the omission of a housing cover,

Fig. 10

8 shows a half cross section along the line XX in FIG. 8,

Fig. 11

7 shows a partial section along the line XI-XI in FIG. 9,

Fig. 12

2 shows an axial front view analogous to FIG. 1 in an embodiment of the rotary piston pump according to the invention,

Fig. 13

a partial axial section along the line XIII-XIII in Fig. 12,

Fig. 14

an axial front view as in Fig. 12, ie in the direction of arrow XIV of FIG. 13, but with the omission of a front housing cover, and

Fig. 15

a view analogous to FIG. 14, but in a further embodiment of the invention.

In the different figures of the drawing, the same or corresponding parts and components are always designated with the same reference numerals, so that each description of a part that may only exist once with reference to a specific figure also applies analogously to the other figures in which this part can also be seen.

A rotary piston pump 1 according to the invention has a pump housing 2 with a cylinder space 4 which has a cylindrical inner peripheral surface 6 (see in particular FIGS. 3 and 5, FIGS. 9 and 10 and FIGS. 14 and 15). The pump housing 2 has at least one inlet 8 and at least one outlet 10, each of which opens into the cylinder space 4 in the region of the inner peripheral surface 6. In the preferred embodiments shown in FIGS. 1 to 7 and in FIGS. 8 to 11, however, several, in particular three, sub-pumps 12, 14 and 16, each of which is arranged uniformly distributed over the circumference of the cylinder space 4, are formed within the pump housing 2, each of which Have inlet 8 and an outlet 10 (see in particular Fig. 1; in the remaining figures, the inlets and outlets are mostly only indicated by dash-dotted lines). The sub-pumps 12, 14, 16 are each offset circumferentially by 120 °. Connection lines (not shown) can be connected to the inlets 8 and outlets 10. A rotary piston 20 is mounted in a rotationally drivable manner within the cylindrical space 4 via a drive shaft 18 coaxial with the cylindrical space 4 or the inner peripheral surface 6. This rotary piston 20 has an outer circumferential surface 22 designed in such a way that, when it rotates, it interacts in a sealing manner with the inner circumferential surface 6 and in regions between its outer circumferential surface 22 and the inner circumferential surface 6 of the cylinder chamber 4, due to a radial “stroke distance”, respective working chambers 24 are formed, the volume of which increases for the suction of a medium to be conveyed starting from the respective inlet 8 and decreases again with continued rotation to displace the medium in the direction of the respective outlet 10.

To separate the individual sub-pumps 12, 14, 16, a separating slide 26, which has an axial length, is arranged between the outlet 10 of one sub-pump 12/14/16 and the adjacent inlet 8 of the sub-pump 14/16/12 closest in the direction of rotation. which essentially corresponds to the axial length (“clear internal width”) of the cylinder space 4, with the exception of a slight play. Each separating slide 26 is mounted in the pump housing 2 so as to be displaceable in an essentially radial direction and acts in a sealing manner with the outer circumferential surface 22 of the rotary piston 20 in order to separate a "suction" working chamber 24 from a "displacing" working chamber 24. This means that during the rotation of the rotary piston 20, each separating slide 26 reciprocates in the radial direction in such a way that its surface 28 facing the rotary piston 20 touches the outer peripheral surface 22 of the rotary piston 20, but preferably via a small, narrow sealing gap (in the Drawings not recognizable) is spaced from the outer peripheral surface 22.

This is achieved in that each separating slide 26 is driven back and forth in both radial directions by a drive device 30 which is synchronized with the rotary piston 20 in such a way that it has the surface 28 facing the rotary piston 20 the "radial stroke distance curve" which follows when the rotary piston 20 rotates past the separating slide 26, the outer circumferential surface 22. The movement of the separating slide 26 is illustrated in the drawing figures by double arrows 32.

As initially illustrated on the one hand in FIGS. 1 to 7 and on the other hand in FIGS. 8 to 11, the drive device 30 is preferably designed as a cam drive and has for this purpose at least one rotating synchronously and coaxially with the rotary piston 20 than in the direction of the axis of rotation 34 Open groove formed cam track (cam) 36, in which for each separating slide 26 a cam 40 connected to this via a motion transmission member 38 is guided. In order to generate as little friction as possible in the region of each cam 40 guided in the cam track 36, each cam 40 is advantageously designed as a cam roller (cam roller) 42 that rotates in the cam track 36 and is rotatably connected to the motion transmission member 38. The cam roller 42 can advantageously be formed by a roller bearing.

The two exemplary embodiments according to FIGS. 1 to 7 on the one hand and FIGS. 8 to 11 on the other hand differ primarily in the structural design of the movement transmission element 38. These differences will now be explained in the following.

1 to 7, the drive device 30 is arranged in a separate housing chamber 46, which is separated from the cylinder space 4 via a partition 44. This housing chamber 46 practically forms a "gear housing". The drive shaft 18 of the rotary piston 20 extends through an opening of the partition wall 44 and through the housing chamber 46 and is mounted in a housing cover 48 closing the housing chamber 46 on its side facing away from the partition wall 44. On the side of the cylinder space 4 opposite the partition 44, the latter is closed by a further housing cover 50. The drive shaft 18 extends through an opening of the housing cover 50 and a bearing arranged here to the outside and can be connected here to a drive element, not shown. The cylinder chamber 4 is sealed on both sides against the drive shaft 18 by means of a shaft sealing ring 52 in each case. In the separate housing chamber 46, a cam 54 is now arranged and torque-connected to the drive shaft 18 so that it rotates synchronously with the rotary piston 20. The cam plate 54 has the cam track 36 on its side facing the partition 44. As already mentioned, each of the cams 40 engaging in the cam track 36 is connected to the associated separating slide 26 via the movement transmission member 38. For this purpose, in this embodiment (see in particular FIG. 2), the motion transmission member 38 consists of a guide tappet 56 connected to the cam 40 and led outwards from the pump housing 2 or the housing chamber 46, and connected to the separating slide 26 and sealed by a seal 58 from the pump housing 2 or the cylinder chamber 4 outwardly guided control plunger 60 and from a connecting part 62 connecting the guide plunger 56 outside the pump housing 2 with the control plunger 60. This connecting part 62 is - as can best be seen in FIGS. 2 and 6 - as Bridge-like driver plate and each rigidly connected to the plungers 56 and 60, in particular screwed. The seal 58 sealing the control tappet 60 is preferred formed as a sealing package from several individual sealing rings. The guide plunger 56 and the control plunger 60 are each guided in a bearing 64 in a direction that is perpendicular to the axis of rotation 34, ie radial, essentially without tilting. Each bearing 64 is preferably designed as a recirculating ball bushing. In addition, the plungers 56 and 60 are of course each arranged in the same circumferential area of the pump which is aligned in the axial direction. Due to the "media-tight" separation of cylinder space 4 and "gear housing" (housing chamber 46), this embodiment is suitable for virtually any medium. In this case, in the area of the drive device 30, it is even possible for lubrication to reduce friction without the medium to be conveyed being contaminated.

In contrast, in the embodiment according to FIGS. 8 to 11 the drive device 30 is arranged together with the rotary piston 20 in the cylinder space 4. As can be seen in particular from FIG. 8, in this embodiment the cylinder space 4 is closed on both sides directly by the housing covers 48 and 50; the sealing to the outside again takes place via the shaft sealing rings 52. Here, the rotary piston 20 preferably has a cam track 36 in each of its two end faces, two cams 40 being provided for each slide valve 26, each of which is guided in one of the two cam tracks 36. The motion transmission member 38 expediently consists of two guide slides 66, which are arranged on the opposite end faces of the rotary piston 20 and each connect one of the cams 40 to an end face of the separating slide 26. This can also be seen best in FIG. 8. The guide slides 66 are each in guide recesses of the pump housing, in particular in guide recesses 68 of the housing covers 48 and 50, guided in the radial direction essentially without tilting. This embodiment of the rotary piston pump 1 according to the invention is particularly suitable for conveying "granular" and viscous (highly viscous) media. With media of this type it can namely be ensured that no medium gets into the area of the drive device 30, although this is arranged within the cylinder space 4.

In the following, advantageous configurations will now be explained, which apply equally to both embodiments of FIGS. 1 to 7 and FIGS. 8 to 11.

Preferably, the inlets and outlets 8, 10 are arranged in such a way and the rotary piston 20 is designed with respect to the areas of its outer peripheral surface 22 which sealingly cooperate with the inner peripheral surface 6 of the cylinder chamber 4 in such a way that in all positions of the rotary piston 20 within each sub-valve 12, 14, 16 the Inlet 8 is separated from the associated outlet 10. This means that there is no direct "through connection" from the inlet 8 to the outlet 10 in any piston position. In the preferred embodiment, this is achieved according to the invention with the three sub-valves 12, 14, 16, each offset by 120 °, in that the rotary piston 20 has a cross section which corresponds at least approximately to a regular polygon, namely at least one pentagon. Advantageously, the rotary piston 20 is rounded in the region of the corners of its cross section - seen in the circumferential direction - convexly rounded. In these areas, the rotary piston 20 acts in a sealing manner with the inner circumferential surface 6 of the cylinder space 4. The sealing effect can - depending on the medium to be pumped - can be achieved by an axially aligned, linear system or by a small, defined sealing gap. In addition, in these areas, the rotary piston 20 can advantageously also have strip-like radial sealing elements, not shown, which extend in the axial direction and then rest sealingly on the inner circumferential surface 6. Furthermore, the rotary piston 20 is preferably concavely curved in the areas of the side faces of its pentagonal cross section, as seen in the circumferential direction. This contributes to the formation or enlargement of the working chambers 24 and thus also to an increase in the delivery volume of the pump. Of course, the convex and concave curvatures of the rotary piston 20 expediently merge into one another. For this purpose, reference is made in particular to FIGS. 3 and 5 or FIGS. 9 and 10. In this context, it is also expedient if the surface 28 of each separating slide 26 facing the rotary piston 20 - again seen in the direction of rotation - is convex.

As already mentioned, this special configuration ensures that no inlet 8 is connected to the associated outlet 10 in any position of the rotary piston 20. Rather, the inlet is always separated from the outlet via at least one “sealing area” of the rotary piston 20. In each case in one position of the rotary piston 20 there are even two "sealing areas" with a working chamber 24 closed off by them between the inlet 8 and the outlet 10 (see in this respect in FIGS. 3 and 9 each the "lower" working chamber 24).

For the sake of completeness, it should now be mentioned that the pump housing 2 is preferably made of stainless steel (e.g. V2A), or of nickel-bronze or plastic. The rotary piston 20 is made of nickel-bronze or plastic. Depending on the application, for housing and / or pistons e.g. a ceramic material can also be used.

The function of the rotary piston pump 1 should already have become sufficiently clear from the above description in conjunction with the drawings. When the rotary piston 20 rotates in the direction of the arrows 70 shown, the respective medium is sucked in through the inlets 8 in the direction of the arrows 72 and subsequently displaced in the direction of the arrows 74 via the outlets 10. At this point, however, it should be noted that the rotary pump 1 is basically suitable for both directions of rotation (clockwise / counterclockwise rotation); in the case of a direction of rotation reversed to the direction of arrow 70, only the functions of the inlets and outlets 8, 10 would "swap", i.e. each inlet 8 would become the outlet and each outlet 10 would become the inlet, so that the arrows 72 and 74 would also be reversed accordingly.

The pump works extremely low in friction and wear, so that even a low drive power is required. The rotary piston 20 is preferably driven at a speed of 16 to 230 l / min (revolutions per minute). A volume of approximately 0.25 l is delivered per revolution. The concrete embodiment with three sub-pumps and "pentagonal" Rotary piston 20 is also particularly advantageous because, when interconnecting all inlets 8 on the one hand and all outlets 10 on the other hand, a very uniform delivery flow is achieved because the pump cycles of the individual sub-pumps differ from one another in time or overlap. In addition, this special embodiment also leads to a "shortening" of the transport routes (in the circumferential direction) within the pump 1 according to the invention, ie the medium is only spread over part of the circumference, here in particular less than 120 ° (angular distance between inlet and outlet 8, 19), promoted by the piston 20. In comparison to the state of the art, where the delivery was almost 360 °, the pump according to the invention "treats" the medium much more "gently".

The invention will now be explained with reference to FIGS. 12 to 15. The rotary piston pump 1 initially illustrated in FIGS. 12 to 14 is specially designed as a “metering pump” in particular for granular, powdery media, ie for those substances which consist of individual, more or less large particles and which therefore do not “flow” like liquids. , but are more "flowable". It is therefore "bulk goods". As can be seen in particular in FIG. 14, the rotary piston pump 1 in this embodiment has only one inlet 8 and also only one outlet 10. In operation, the rotary piston pump 1 is arranged in relation to its position in space so that its axis of rotation 34 runs essentially horizontally. Inlet 8 and outlet 10 are diametrically opposed to one another and at least approximately on the vertical, the inlet 8 pointing upwards as the housing opening during the Outlet 10 is opened vertically downwards. In the area of the inlet 8 there is expediently an inlet funnel (not shown here) for receiving and feeding the respective substance, the substance then sliding down into the inlet 8 mainly due to gravity (trickling). The inlet 8 is - seen in the direction of rotation of the rotary piston 20 (see arrow 70 in Fig. 14) - a first slide valve 26, and the outlet 10 is followed by a second slide valve 26, so that the inlet 8 into the cylinder chamber 4 medium is then transported via the working chambers 24 to the outlet 10 (entrained), where it then falls out of the pump 1 essentially due to gravity. The two separating slides 26 correspond - in particular with regard to their "positive drive" via the drive device 30 - to the above explanations, so that reference can be made here. However, the separating slides 26 do not separate "sub-pumps" here because there is only one pump (one inlet and one outlet) per se.

According to the invention, a metering device 80 is now provided which serves to vary the "cycle delivery volume" delivered in each of the work chambers 24 in each working cycle, preferably setting the respective cycle delivery volume from zero to one of the maximum volume of the respective one Working chamber 24 corresponding maximum value is possible in particular continuously.

In the exemplary embodiment according to FIGS. 12 to 14 - see in particular FIG. 14 in this regard - the metering device 80 is arranged between the inlet 8 and the outlet 10, for which purpose the inlet 8 in the direction of rotation (arrow 70) of the piston 20 seen, ie on its side opposite the separating slide 26 in the direction of rotation, is limited by a metering slide 82 forming the metering device 80. This metering slide 82 is mounted on a holder 84 in such a way that it can be adjusted relative to the holder 84 in a radial direction relative to the holder 84, preferably via a screw spindle 86 (see the double arrow 87), so that between the outer circumference 22 of the rotary piston 20 and at the end of the metering slide 82 facing this, an inlet gap 88 is formed with a variable clear width measured in the radial direction. The holder 84 carrying the metering slide 82 is driven back and forth in a radial direction — analogous to the separating slide 26 —by the drive device 30 (see FIG. 13), which is illustrated by the corresponding double arrow 32. For this purpose, the holder 84 of the metering slide 82 is connected to a cam 89 which is guided in the cam track 36 already mentioned, so that the metering slide 82 is also driven synchronously with the rotation of the rotary piston 20. This is necessary because the metering slide 82, when set for a reduced delivery volume, projects radially into the cylinder space 4 in some areas, as can also be clearly seen in FIG. 14, but the drive of the holder 84 ensures that the metering slide 82 deviates radially outwards when the sealing areas of the rotary piston 20 each pass the area of the metering slide 82.

Also particularly in FIG. 14 it can be clearly seen that the working chamber 24 which forms after the inlet 8 when the rotary piston 20 rotates and increases in volume can only fill via the inlet gap 88 formed by the metering slide 82, so that the "degree of filling ", that is, the stroke volume conveyed in one of the working chambers 24 is variable as a result.

This described embodiment of the rotary piston pump 1 according to FIGS. 12 to 14 with the metering slide 82 is particularly suitable for granular and powdery media, such as beverage and soup powder, but - at least to a limited extent - also for viscous to pasty media. For thinner media, this version can be used if the metering slide 82 has a "longer" sealing surface, as seen in the direction of rotation of the piston 20, since this would cause the inlet gap 88 as "throttle gap" to increase the flow resistance for the medium. In this context, however, it is particularly advantageous to also let a certain volume of air into the working chamber 24 which enlarges behind the inlet 8 and the metering slide 82, the volume ratio of medium: air then being variable according to the invention.

As can now be seen in FIG. 15, an adjustable ventilation valve 90 is provided for this purpose, it being pointed out that this ventilation valve 90 can in principle also be used without the metering slide 82, so that the ventilation valve 90 itself forms the metering device 80. In the preferred embodiment shown in FIG. 15, however, the metering slide 82 and the ventilation valve 90 are combined with one another.

In the direction of rotation of the piston 20 immediately behind the housing opening forming the inlet 8 and - in the example with metering slide 82 - behind the metering slide 82 opens into the area of the enlarging working chamber 24 Housing channel 92 (shown in dashed lines in FIG. 15), which is connected to the outside air via the ventilation valve 90. The ventilation valve 90 is now designed in such a way that the air volume drawn in through the housing channel 92 can preferably be changed from zero to a specific maximum value.

As already indicated, the delivery volume of the medium is metered through the ventilation valve 90 in that part of the medium always flows in the direction of the arrow 94 and part of the air in the direction of the arrow 96 and these parts are conveyed in this way, the "mixing ratio" via the ventilation valve 90 - and if necessary in cooperation with the metering slide 82 - in particular continuously variable.

The embodiment with the metering slide 82 also offers the advantageous possibility of counting the particles in the case of granular media which consist of individual particles, such as grains, tablets or the like, ie a specific, defined number of each delivery cycle in each working chamber 24 To transport particles to the outlet 10 so that they can then be packed in the required number of pieces in packaging, for example. For this purpose, the rotary piston 20 preferably has, in its outer circumference 22, receiving recesses (not shown) for one of the particles in each case. The metering slide 82 is then set to an inlet gap 88 in such a way that it only strips off any surplus, that is to say the particles which are not seated in the receiving recesses, and thus does not get into the working chamber 24. For safe, uniform "filling" of all receiving recesses of the rotary piston 20, it can be advantageous to set the rotary piston pump 1 according to the invention in vibration during operation.

In an embodiment of the invention, not shown in the drawing, the metering device 80 can also be formed in that the axial length of the working chambers 24 seen in the direction of the axis of rotation 34 and thus also the volume thereof is variable. For this purpose, the rotary piston, the pump housing and the separating slide each consist of at least two telescopically telescopic parts.

The metering device 80 according to the invention thus enables precise metering of the stroke delivery volume in all the possible configurations mentioned. The specific gravity of the medium in question can then be used to easily meter the weight using this volume metering. The metering device 80, that is to say in particular the metering slide 82 and / or the ventilation valve 90, can be equipped with a scale (for volume and / or weight, for example) which is determined empirically, as a result of which the metering is very simple. The medium falling out of the outlet 10 can thus be processed cyclically as a packaging unit, for example, be filled directly into certain packaging. According to the invention, the metering device 80 can also be set automatically by means of an electronic control device, in particular, by merely entering a desired weight or volume as the desired value; the control device then automatically initiates a corresponding setting of the metering device 80, and automatic readjustment can also be carried out by comparing the actual value / setpoint.

Within the scope of the invention it is possible to drive several (at least two) rotary piston pumps together, coaxially one behind the other, in which case advantageously only one common drive (only one cam track with outward movement transmission members) is required for the existing separating slide and for the metering slide (s) that are preferably present . Furthermore, the drive device driving the isolating slide (s) can in principle be realized by any suitable type of drive, such as a gear / eccentric drive or a servo (motor) drive, in the latter case synchronization with the rotation of the rotary piston via a electronic, programmable logic control can take place.

Claims (15)

1. Rotary piston pump for delivering flowable or pourable media, in particular liquid, pasty or granular media, comprising a pump housing (2) with a cylinder space (4) which has a cylindrical inner circumferential surface (6) and into which there open at least one inlet (8) and at least one outlet (10), and also a rotary piston (20) which is mounted inside the cylinder space (4) so as to be rotationally drivable about an axis of rotation (34) coaxial with the said cylinder space and has an outer circumferential surface (22), the radial distance from the axis of rotation (34) of which varies over the circumference in such a way that the rotary piston (20) cooperates, by at least one region of the outer circumferential surface (22), sealingly with the inner circumferential surface (6) of the cylinder space (4) and in certain regions is spaced from the inner circumferential surface (6) by a stroke distance radial to the axis of rotation (34), so that on rotation of the rotary piston (20) a working chamber (24), increasing in volume, is formed in each case in the region of the inlet (8) in order to draw in the medium to be delivered, which working chamber then decreases again in volume, after continued rotation, in the region of the outlet (10) in order to force out the medium, the respective working chamber (24) being bounded, at least during its volume increase and decrease, by at least one separating slide (26) which, seen in the direction of rotation, is arranged before the inlet (8) and after the outlet (10) and on rotation of the rotary piston (20) is displaced to and fro in the pump housing (2) in the substantially radial direction with respect to the axis of rotation (34) in such a way that it always cooperates, by its surface (28) facing the rotary piston (20), sealingly with the outer circumferential surface (22) of the rotary piston (20), the displacement of the separating slide (26) being effected in constrained fashion by means of a drive device (30) synchronised with the rotary piston (20), characterised in that a metering device (80) is provided for varying the cycle delivery volume, delivered in in each case one of the working chambers (24), of the particular medium.
2. Rotary piston pump according to Claim 1, characterised in that it is possible to carry out, in particular in an infinitely variable manner, with the metering device (80), a change in volume from zero up to a maximum value corresponding to the particular volume of the working chamber (24).
3. Rotary piston pump according to Claim 1 or 2, characterised in that the metering device (80) has a radially arranged metering slide (82) which - seen in the direction of rotation (70) - is arranged immediately after the inlet (8) and is fastened to a holder (84) so as to be adjustable relative thereto in the radial direction in such a way that a variable inlet gap (88) for the medium is formed between the outer circumference (22) of the rotary piston (20) and the metering slide (82), the holder (84) being driven in constrained fashion to and fro in the radial direction, together with the metering slide (82), synchronously with the rotation of the rotary piston (20) via the drive device (30).
4. Rotary piston pump according to one of claims 1 to 3, characterised in that the metering device (80) has an adjustable ventilating valve (90), via which the outside air is drawn with a variable volume into the working chamber (24) increasing in its volume after the inlet (8), so that a metering of the medium is effected by variation of the volume ratio of the medium to the drawn-in air.
5. Rotary piston pump according to one of claims 1 to 4, characterised in that the rotary piston (20) has in its outer circumference (22) receiving depressions for in each case one particle of the medium consisting of a multiplicity of particles of the same kind, such that, in the working chamber (24), in each case only a defined number of particles corresponding to the receiving depressions present within the region of the working chamber (24) are delivered, excess particles being retained by the metering slide (82).
6. Rotary piston pump according to one of Claims 1 to 5, characterised in that the separating slide (26) is always spaced by a defined sealing gap from the outer circumferential surface (22) of the rotary piston (20).
7. Rotary piston pump according to one of Claims 1 to 6, characterised in that the drive device (30) is designed as a cam drive and preferably has at least one cam path (36) which rotates synchronously and coaxially with the rotary piston (20) and is designed as a groove open in the direction of the axis of rotation (34) and in which there is guided in each case one cam (40) connected to the separating slide (26) via a movement-transmission link (38).
8. Rotary piston pump according to one of Claims 1 to 7, characterised in that the drive device (30) is arranged in a separate housing chamber (46) separated from the cylinder space (4) via a separating wall (44), a cam disc (54) which contains the cam path (36) and is connected, in particular directly, to a drive shaft (18) of the rotary piston (20) being preferably arranged in the separate housing chamber (46), the movement-transmission link (38), which connects the cam (40) engaging in the cam path (36) to the separating slide (26), comprising a guide tappet (56) connected to the cam (40) and guided out of the pump housing (2) to the outside, a control tappet (60) connected to the separating slide (26) and guided in a sealed-off manner out of the pump housing (2) to the outside, and also a connecting part (62) connecting the guide tappet (56) to the control tappet (60).
9. Rotary piston pump according to one of Claims 1 to 7, characterised in that the drive device (30) is arranged, together with the rotary piston (20), in the cylinder space (4), the rotary piston (20) preferably having in its two end faces in each case one cam path (36) and two cams (40) guided in in each case one of the two cam paths (36) being provided for the/each separating slide (26), and also the movement-transmission link (38) comprising two guide slides (66) which at the opposite ends of the rotary piston (20) connect in each case one of the cams (40) to one end of the separating slide (26).
10. Rotary piston pump according to one of claims 1 to 9, characterised in that a plurality of partial pumps, in particular three partial pumps (12, 14, 16), arranged so as to be distributed uniformly over the circumference of the cylinder space (4), in each case with one inlet (8) and one outlet (10), are formed inside the pump housing (2), in each case one inlet (8) of one of the partial pumps (12, 14, 16) preferably being adjacent, with a small interval, to one outlet (10) of the partial pump (16, 12, 14) adjacent in the direction counter to the direction of rotation and one of the separating slides (26) being arranged in each case between the inlet (8) of the one partial pump and the outlet (10) of the other partial pumps.
11. Rotary piston pump according to one of Claims 1 to 10, characterised in that the inlets and outlets (8, 10) are so arranged, and also the rotary piston (20) is so designed with respect to the regions of its outer circumferential surface (22) which cooperate sealingly with the inner circumferential surface (6) of the cylinder space (4), that the inlet (8) is separated from the associated outlet (10) in all positions of the rotary piston (20).
12. Rotary piston pump according to one of claims 1 to 11, characterised in that the rotary piston (20) has a substantially regular-polygonal, in particular regular-pentagonal, cross-section.
13. Rotary piston pump according to Claim 12, characterised in that the rotary piston (20) is designed in the region of the polygon corners - seen in the circumferential direction - so as to be rounded in a convexly curved manner and cooperates sealingly with the inner circumferential surface (6) of the cylinder space (4) in these regions, the rotary piston (20) being designed in the region of the polygon sides - seen in the circumferential direction - preferably so as to be concavely curved.
14. Rotary piston pump according to one of Claims 1 to 13, characterised in that the surface (28), facing the rotary piston (20), of the/each separating slide (26) is designed - seen in the direction of rotation - so as to be convexly curved.
15. Rotary piston pump according to one of Claims 1 to 14, characterised in that the rotary piston (20) has, in the region(s) cooperating sealingly with inner circumferential surface (6) of the cylinder space (4), in each case one strip-like radial sealing element which extends in the axial direction and lies sealingly on the inner circumferential surface (6).

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