GB2154284A

GB2154284A - Multiple discharge gear pump

Info

Publication number: GB2154284A
Application number: GB08503978A
Authority: GB
Inventors: Siegfried Hertell
Original assignee: Barmag Barmer Maschinenfabrik AG
Current assignee: Oerlikon Barmag AG
Priority date: 1984-02-15
Filing date: 1985-02-15
Publication date: 1985-09-04
Also published as: IT8519383A0; GB8503978D0; IT1183178B; GB2154284B

Abstract

In apparatus for producing a large number of identical, independent (small-volume) streams of liquid, a gear pump comprises a housing 1 provided with toothing 6 engaged by at least one pinion 8 guided by a rotor 9. A supply of fluid (12, Fig. 2) leads to an annular passage 14 in the interior of the rotor and thence to the toothing, whereas fluid is discharged through outlets 15 which proceed from the toothing. Back-flow is prevented by valves 20, which may instead comprise slide valves. The rotor has a circular-cylindrical outer surface 21 which is adapted to the interior of the pump housing 1 defined by the addendum circle 5 of the toothing 6 and has at least one circular-cylindrical pocket 7 for accommodating a pinion 8 meshing with the toothing 6. In alternative embodiments the pinions are carried on journals and may instead engage with toothing formed on the outer surface of a stationary gear located within the housing 1. <IMAGE>

Description

SPECIFICATION Gear pump with internal toothing The invention relates to an apparatus for producing a large number of identical independent and small-volume streams of a liquid.

One application of this type of apparatus is, for example, the supply of an accurately metered quantity of a fluid, for cooling with water, for lubricating with a finishing fluid or the like, to the yarn at each working position of a textile machine with a plurality of such positions. Any difference between the individually metered quantities leads to deviations of the yarn properties and thus to inferior quality. A particular difficulty arises when only a very small quantity of a liquid needs to be supplied to each working position. This quantity is adapted to the yarn weight passing through, and may be less than 1%. At any rate, it is less than 50% of the yarn weight.

Up to now, one pump each has been used at each working position for applying this metered quantity. Aside from the constructional expense, this means that the application of a metered quantity is dependent on an identical condition and identical operation of the pumps.

Another know possibility is the production of an aggregate stream of fluid by a single pump, which is then throttled and distributed to the individual working positions. However such an apparatus is very inaccurate.

Gear pumps of different designs are widely used. Also constructions have become known which produce several identical volume streams at the same time. Such a gear pump is, for example, described in German Offenlegungsschrift 20 16 171. A ring with internal toothing is easily movably inserted into an annular groove worked into a housing plate.

Distributed over the circumference of the annular groove, the housing plate contains circular cylindrical pockets in which pinions are stationarily supported which mesh with the gear ring.

One pinion is driven and in turn drives the gear ring and the other pinions. Supply lines lead to the teeth leaving a meshing engagement, and discharge lines lead away from the pinion teeth entering a meshing engagement.

Thus, the mode of operation corresponds with that of pumps having two meshing gears.

Although in the described example three identical streams are produced, it is not possible to supply a larger number of users with this type of pump. Furthermore, only a continuous flow of fluid is supplied to each user.

For supplying a larger number of users with relatively small quantities of fluid, no gear pumps have yet become known. Although very accurately operating metering pumps are available, in which piston and plunger are used to determine the quantities, they are found to be very costly and susceptible to breakdown when the conveyed fluid is without any lubricating properties. Furthermore, this type of pump does not practically allow the supply to a larger number of users from one unit.

Accordingly, it is object of the invention to make available a metering pump which allows the supply, at a justifiable cost, to a larger number of identical users, i.e. without interposing additional metering devices. To accomplish this object of the present invention, a gear pump is used which is adapted to this new function as follows: The housing plate is provided with a circularly cylindrical opening which contains an internal toothing. A rotor with its cylindrical external surface is fitted, practically free from play, into the interior which is defined by the addendum circle of this internal toothing. On its circumference, the rotor has one or several cylindrical pockets, evenly distributed, if necessary. The centres of these pockets are on a circle, the diameter of which is by the double pocket diameter smaller than the dedendum circle of the internal toothing.The rotor contains an annular duct between the pockets which is connected with a supply line and provided with tap lines to the rotor circumference.

Outlet ducts proceed from the internal toothing which are secured by return flow stops, and the mutual angular distance of which is not greater than one half of the sector angle between the two corners of the pocket opening for the engaging pinion teeth on the rotor circumference.

Preferably, the pinions distributed over the rotor circumference are floatingly supported in the rotor pockets and secured by the housing covers adjoining their front sides with a minimal play. The outlets ducts proceeding from the internal toothing, for example from its dedendum circle, leading radially outwardly and being, for example, secured by nonreturn valves, need little space; their possible number is essentially determined by the diameter ratio of internal toothing and pinion, or the ratio of the pitch circles, respectively, and the module or the addendum.

A duplication or even a multiplication of the number of the positions to be supplied result in a further development, in which the pump rotor is composed of two or more identical, individual plates. Pockets are provided for the pinions in each plate in such a staggered arrangement that they have the same angular distance from each other, when looked at jointly. Neighbouring rotor discs are separated by circular discs concentric to them, the outside diameter of which is larger than the dedendum circle diameter of the internal toothing. The uniform internal toothing extends across the full width of the composite rotor is divided by intermediate grooves, at a distance exactly corresponding to the thick ness of the individual rotor discs, into areas corresponding to the individual rotor discs.

Further, the circular discs move into the intermediate grooves separating the working areas from each other.

Although it is, in principle, possib!e to combine in the above described manner several structural assemblies differing from each other, a complication will result, even though there are also instances in which such a proceeding may be advisable.

In a further embodiment, the pinions are supported on journals. For this purpose, the rotor is provided with a concentric bearing plate, to which the journals are attached. An additional plate reinforces the housing formed by the housing plate with internal toothing and contains a bore concentric to, but with a larger diameter than, the internal toothing, into which bore the bearing plate fits in diameter and thickness.

This embodiment allows duplication in a simple manner, in that the bearing plate is placed between two rotor plates and the additional plate of the housing between two housing plates with internal toothing. Likewise, it is possible to join identical assemblies, or assemblies differing from each other, as is described above in connection with the floatingly supported pinions. Furthermore, there results another possibility of securing against a return flow of the pumped fluid.

For this purpose the bearing plate must have a minimum diameter which is by some extent larger than the diameter of the dedendum circle of the internal toothing. The outlet ducts do not extend radially outwardly, but extend paraxially outside the area of the dedendum circle and start on the front side of the housing plate facing the bearing plate of the rotor. The bearing plate itself has an outside diameter which clearly projects beyond the inlet openings of the paraxial outlets.

Groove-shaped recesses are worked into their front sides facing the inlet openings, which extend in radial direction from the addendum circle of the internal toothing to a circle enclosing the inlet openings of the outlet ducts, and reach, in circumferential direction, across a sector angle which is smaller than the angular distance of neighbouring outlet ducts by the diameter of the inlet to the outlet duct.

The beginning of the groove-shaped recess corresponds with the corner of the pocket opening on the rotor circumference which is forwardly located in the rotational direction of the rotor. Also, it is possible to let the outlet ducts extend radially. In this case, however, they do not proceed from the internal toothing, but from the front side of the housing plate accommodating the internal toothing which faces the bearing plate, wherefrom they first extend paraxially and then radially outwardly.

With the use of pin ions, which rotate on paraxial journals anchored in a bearing plate, the rotor may be left out or have an outside diameter which can be considerably smaller than the addendum circle diameter of the internal toothing. In this instance, however, it is advantageous to provide each pinion on its front side as seen in the rotational direction, with a tooth cover which adjoins both the addendum circle of the pinion and the addendum circle of the internal toothing in the area of penetration of the pinion teeth. The cover is then in contact either with the rotor or, in the absence of a rotor, with the additional plate. It should be so dimensioned that it overlaps one to one and one half tooth pitches both at the internal toothing and pinion.

In another preferred embodiment, the housing of the pump consists of one or two plates is provided with a stationary, i.e. non-rotating, gear located in an inside space which connects to the fluid inlet. Pinions which are freely rotatably supported on or in a rotor and which rotate with the same, engage with the stationary gear. The toothings of the stationary gear and pinions are so designed that the tooth gaps of the stationary gear form, when engaged with the rotating gear (pinion), a closed cell. This can be accomplished in that the toothings mesh substantially without play and that, while engaged, both flanks of the tooth moving in are in constant contact with the tooth flanks defining the tooth gaps.

Another possibility of forming the toothing is that an overlapping degree of two is chosen. In so doing, the equidirectional flanks of at least two successive teeth of the outside gear rest free of play against the oppositely directed flanks of at least two successive teeth of the rotating gears, so that the tooth gaps from an S- or Z-shaped cell.

Since the tooth gaps of the stationary gear are laterally closed by a housing cover or by the adjoining front side of the rotor, each tooth gap of the stationary gear forms a metering chamber to which there is respectively associated an outlet duct. Each outlet duct is connected to a user via a non-return valve or a slot regulating mechanism to stop a return flow.

The number of pinions rotating with the rotor and engaging with the stationary gear may be limited to one pinion, or may be any desired number with corresponding overall dimensions. However, it has been found suitable not to exceed ten, and six pinions is preferable. A minimum number of two pinions is preferred. Generally, the pin ions rotate on journals which are attached to the front side of the rotor facing the interior of the pump, which journals extend in paraxial alignment into the interior of the pump.

The stationary gear may be a ring with internal toothing which is inserted into a corresponding bore in the housing plate and secured against rotation. The internal toothing can also be worked into the housing plate which is provided with a corresponding bore.

Likewise, the stationary gear can be an exter nal gear provided with teeth on its outer circumference. In the latter instance, the housing plate contains a circular-cylindrical bore, the diameter of which corresponds at least to that of the addendum circle of the circle described by the pin ions, but is prefera bly larger.

Regardless of the type of the stationary gear, the pinions can rotate, in the above described manner, on journals. However, they can also be floatingly supported. To provide a floating bearing support, a rotor disc is attached to the rotor, which disc projects into the interior of the housing. Using a stationary internal toothing, the disc is solid and has a smaller diameter than the addendum circle of the toothing. When a stationary external toothing is used, the disc has the shape of a ring, with the inside diameter of be ring being greater than the addendum circle of the exter nal toothing, and likewise the outside dia meter is larger than that of the addendum circle of the circle circumscribed by the pi nions. Circularly cylindrical recesses are worked into the rotor disc for receiving the pin ions floatingly supported therein.With the use of a stationary internal toothing, these recesses extend through the cylindrical outer surface of the rotor disc, and likewise the inner ring surface in the area of the engaging pinion teeth, when a stationary external toothing is used.

The outlet ducts intermittently receiving the conveyed fluid should be secured by a stop against a return flow of the fluid. This may be accomplished with the use of non-return valves, when the outlet ducts proceed in the dedendum circle from the tooth gaps of the internal toothing and extend radially outwardly. Another possibility which prevents clogging more efficiently, is to use the principle of a slide-valve gear. The solutions of the present invention differ for the two described forms of the stationary gear. In both cases, however, the inlet sections of the outlet ducts extend paraxially to the rotor axis.

In the design of the pump with a stationary external gear, the outlet ducts are accommodated in that housing cover which is located on the side of the gear turned away from the rotor. Its inlets are located on a circle the diameter of which preferably ranges between that of the dedendum circle and that of the pitch circle of the stationary external gear. The inlets to the outlet ducts respectively face the tooth gaps. A valve disc located between the stationary gear with the pinions engaging therewith and the inlets to the outlets ducts, is operative as a slide and possesses in the area of the latter a valve bore for each pinion.

These valve bores are so arranged that they lie on the respective connecting straight line between the rotor axis and the pinion axis. To improve the sealing of the overflow area, the rotor with the pinions, the external gear and the valve plate are axially displaceable and pushed by spring pressure against the inside wall of the housing cover.

In the design of the pump with a stationary internal toothing, the inlets to the paraxially extending sections of the outlet ducts are arranged in a circle on the front side of the internal toothing facing the rotor. The diameter of this circle is larger than the diameter of the dedendum circle of the internal toothing by at least twice the diameter of the inlets to the outlet ducts. Radially extending grooves are worked into the front side of the rotor facing the inlets to the outlet ducts, which grooves extend from the circumference of the circle circumscribing the inlets to the outlet ducts, into the circle, which includes the addendum circles of the pinions, and which grooves preferably extend to the area of the pitch circle of the internal toothing.The position and number of grooves per pinion directly arranged side-by-side depends on the position and number of the tooth gaps in the internal toothing respectively simultaneously closed by the immersing teeth of a pinion, with the centre lines of the grooves extending in the planes passing through the rotor axis and coinciding with the plane of symmetry of the respectively corresponding tooth gaps.

For each pinion up to a maximum of three grooves are provided, the arrangement of which is defined by having the last groove with its centre line, as seen in the rotational direction of the rotor, coincide essentially with the rotor diameter which extends through the axis of the respective pinion.

Preferred embodiments of the present invention are described in detail below, by example only, with reference to the accompanying drawings, wherein: Figure 1 is a side elevation with the housing cover removed; Figure 1 a is another side elevation with the housing cover removed; Figure 1 B is a side elevation of another embodiment; Figure 2 is a sectional view with floatingly supported pin ions; Figure 3 is a sectional view with pinions supported on journals; Figure 3A is a cross-sectional view of Figure 1 B; Figure 4 shows a gear pump with internal gear, being section 1-1 of Figure 2; Figure 5 is a section along ll-ll of Figure 4; Figure 6 shows a pump with internal toothing and slide-valve gear; Figure 7 is a section along IV-IV of Figure 6;; Figure 8 is a sectional view of an embodiment with a stationary gear with external toothing; Figure 9 shows an individually sealing tooth profile; and Figure 10 shows a tooth profile forming S or Z-shaped cells; and Figure 11 and 1 2 show cross-sections of two further embodiments.

The illustrated gear pump consists of a housing plate 1 with an internal toothing 6, which is defined by the pitch circle 29, the outwardly located dedendum circle 11 and the inwardly located addendum circle 5. It further comprises a rotor 9, the outer circumference of which is practically identical with the circular cylinder coinciding with the addendum circle of the internal toothing 6. It is located practically free from play in the bore circumscribed by the addendum circle 5. Distributed over its circumference, it contains circular-cylindrical pockets 7, the centres of which are arranged on a circle 10 concentric to rotor 9 and which intersect the outer circumference 21 of rotor 9.The thus formed pocket openings are defined by corners 1 8 and 19 and form the opening dimension for the angular distance 1 6 of the neighbouring outlet ducts 1 5. The pockets receive pinions 8 precisely fitting into same, the toothing of which correspondings with the internal toothing 6 of housing plate 1, and which pinions engage, through the pocket openings, with the internal toothing. The corners 18, 1 9 defining the pocket openings are slightly rounded.

The housing plate 1 with rotor 9 and pinions 8 is capped by the two housing covers 2 and 3. Cover 3 serves as a bearing for the drive shaft 28 or rotor 9. Cover 2 contains an inlet 12, which serves as a supply line for the pumped fluid, and from which a distributor 25 leads to an annular duct 14 provided in the rotor and interconnecting the pinion pockets 7. From annular duct 14, tap lines 1 3 to the external surface 21 of the rotor 9 to provide for the toothing gaps in the internal toothing 6 between the neighbouring pinions 8 to be filled.The angular distance 1 6 between the outlet ducts should be more or less so dimensioned that it approximately corresponds to the half 1 7 of the sector angle which is defined by the two corners 1 8 and 1 9 of the pocket openings in the external surface 21 of rotor 9, and which should not, if possible, be greater.

Figure 3 is a sectional view of an embodiment of the gear pump according to the invention, in which pinions 8 rotate about a journal 24 mounted on a bearing plate 22.

For this purpose, housing plate 1 is combined with an additional plate 4 which also contains a circular-cylindrical opening 23. The opening 23 suitably has a larger diameter than the addendum circle 5 of the internal toothing 6 and accommodates the bearing plate 22 of rotor 9.

In a further embodiment a return flow stop other than that shown in Fig. 3 is accomplishing with the use of bearing plate 22. This return flow stop is described below with regard to Fig. 3A. It is in the form of a slidevalve gear for the outlet ducts 1 5. For this purpose, it has, like the bore 23 accommodating it, a diameter which clearly projects beyond the dedendum circle 11. The outlet ducts 1 5 do not extend, or extend only with their last section, radially outwardly. At least the first section from the inlet to all outlet ducts extends paraxially, and their inlets are arranged in a circle concentric to the internal toothing 6, which is larger than the dedendum circle 11 by not less than twice diameter of the inlet ducts.

They are arranged on the front side 26 of housing plate 1 facing the bearing plate.

Worked into the front side of bearing plate 22 are, in the area of the pocket openings 18, 19, groove-shaped recesses 39 which extend in a radial direction from addendum circle 5 to beyond the openings of the outlet ducts 1 5 and cover, in a circumferential direction, a sector angle which is smaller than the angular distance between neighbouring outlet ducts 1 5 by the diameter of an opening to an outlet duct. The groove-shaped recesses are so aligned relative to the pinions that they extend from the one corner 1 8 or 1 9 of an individual pocket opening, which is in front in the rotational direction 27, to the other corner 1 9 or 1 8 of the same pocket opening.

The embodiments of both Figures 2 and Figure 3 allow enlargements to the extent that two or also several housing plates are arranged side-by-side or one after the other. To separate the pressure areas of neighbouring sections in the embodiment of Figure 2, the successive rotor plates 9 may be separated from each other with the aid of thin discs, which sink in corresponding grooves, and which may be produced by intermediate discs, between likewise successive housing plates 1. In the embodiment of Figure 3, the bearing plates 22 may serve as a separation with a particularly simple duplication in that the additional plate 4 and the bearing plate 22 are arranged in the centre and a housing plate 1 and a rotor 9 with pinions 8 are placed on each of their sides.

The gear pump thus described allows a large number of user position to be supplied at intervals from one pump with the same quantity of fluid.

In the embodiment of Figure 1A, the pocket openings in the outer surface of the rotor are enlarged in that a portion of the sharp corners of the rotor is removed. This step allows the sector angle which encloses the pocket openings to be adapated to the angular distance of the outlet ducts, whereas the angular distance of the outer ducts is again dependent on the tooth pitch. A relief groove may be provided in the additional plate 4 which rotates also.

This relief groove 55 engages radially with the bottom of the tooth gaps in pinion 8 and extends, in a circumferential direction, from about the line connecting the centres of rotor 9 and pinion 8 over so many tooth pitches that the groove is in constant connection with the rotating pressure chamber.

This step may be necessary where there is little flank clearance to relieve the pressure in the tooth gaps of pinion 8. For the purpose of relieving pressure, a sufficient flank clearance should be provided in the embodiment of Figure 2.

Another embodiment of this invention is shown in Fig. 1 B and 3A. The housing 1 of the pump has inner teeth 6. The rotor 22 is mounted on axle 28 which is rotatably mounted within the housing. The cross-section of the pump shown in Fig. 1 B corresponds to Fig. 3A.

Two gears are rotatably mounted on axles 24 to the rotor 22 and are in meshing engagement with the teeth of the housing plate 1. The outlets of the pump shown in Fig. 1 B correspond to those shown in Fig. 3A, with the groove 39 not being shown. A tooth cover 54 is fixed to the rotor 22 and protrudes from the rotor and has the same thickness as has the gears 8 which in turn corresponds to the thickness of the housing 1 and the teeth affixed thereto. The tooth cover 54 has two side walls which correspond to, and match with, the crown circles of the teeth of the housing 1 and the teeth of the respective gear at a circumferential distance which corresponds to at least 1 1/2 tooth pitch. The tooth cover--under this condition-may also have the shape as shown in Fig. IA, where the tooth cover also bears the designation 54.

The tooth cover serves the function to provide a compression chamber in the gap existing between the teeth of the housing and each of the gears, and to tighten this compression chamber.

Figures 4 and 5 illustrate a gear pump with internal toothing 6 and two pin ions 8 engaging with same. The pump housing consists of a housing plate 1 with internal toothing 6 and outlet ducts 1 5 with nonreturn valves 20 to stop return flow. The outlet ducts 1 5 emanate from the dedendum circle 11 of internal toothing 6, i.e. from the bottom of tooth gaps 36, and extend radially outwardly to the circular-cylindrical circumference of housing plate 1. The housing further includes additional plate 4, which contains a circular-cylindrical bore 23 with a diameter which is larger than the diameter of the dedendum circle of the internal toothing 6. In this bore 23, there rotates rotor 22 mounted on drive shaft 28 and supported in same, which rotor forms simultaneously the bearing plate for the pinions 8.The pinions rotate about journals 24, which again are inserted in rotor 22 and axially aligned.

Housing covers 2 and 3 cap both sides of the housing consisting of plates 1 and 4.

Housing cover 2 adjacent to the rotor contains the bearing for the drive shaft 28. The second housing cover 3 accommodates the inlet opening for the pumped fluid. It further possesses on its inside a circular-cylindrical recess 25, the outside diameter of which, as shown in Figure 1, overlaps at least the portion of pinions 8 facing the rotor axis. During operation, the entire interior space 30 is filled with the pumped fluid. Screws (not shown) hold the gear pump together.

An embodiment of the invention which is somewhat modified from those previously described is explained below, also in conjunction with Figure 4. The numerals applying only to this embodiment are indicated in parentheses for a better understanding.

Rotor plate 22 holds a rotor disc (9) which projects into the interior 30 of the pump, and the circular-cylindrical external surface (21) of which has a diameter which is smaller than the addendum circle 5 of the internal toothing 6. Its thickness is practically the same as that of housing plate 1 and only smaller by the necessary running clearance between itself and the housing cover 3. Worked into the rotor discs are circular-cylindrical pockets (7), the diameter of which is adapted to the that of the addendum circle 49 of the pinions.

They extend through the circular-cylindrical external surface (21) of rotor discs (9) and accommodate the floatingly supported pinions 8. Also in this embodiment, the housing cover 3 has a circular-cylindrical recess 25 on its inner side. Here, however, the diameter of rotor disc (9) should preferably be larger than that of recess 25. With the arrangement of outlet ducts 15, the rotor can, in a simplified embodiment, consist only of rotor disc 9, additional plate 4 being then no longer needed.

Another advantageous embodiment of the gear pump is illustrated in Figures 6 and 7. It differs from that of Figure 4 in that it has a different type of return flow stop 20. Here, the outlet ducts 1 5 do not proceed from the bottom of tooth gaps 36, but from the inlets 40 to the outlet ducts located on the front side of internal toothing 6 adjacent rotor 22.

The inlets 40 to the outlet ducts are located on a circle 44 which is concentric to the internal toothing, and the diameter of which is larger than that of dedendum circle 11 of internal toothing 6 by at least twice the diameter of inlets 40. The rotor itself is provided on its front sides 26 facing the inlets 40 with radially extending grooves 39, which become operative as a slide-valve gear, and which extend between the inlets 40 and the portion of tooth gaps 36 between pitch circle 29 and dedendum circle 11. The grooves 39 are respectively associated to the pinions 8.Their width measured in the circumferential direc tion is at the most the same as the dedendum width 46, whereas both the number and position of the grooves 39 arranged directly side-by-side in the area of the respective pinion correspond to the position and number of the tooth gaps 36 of internal toothing 6 which are respectively simultanously closed, upon entry, by the teeth 35 of a pinion 8.

They are so arranged that their centre lines extend in the planes passing through the rotor axis and coinciding with the planes of symmetry of the respectively corresponding tooth gaps 36. For each pinion 8 up to a maximum of three grooves 39 are provided and so placed that, in circumferential direction 27 of rotor 22, the centre line of the last groove 39 coincides essentially with the diameter of the rotor 22 passing through the axis of the respective pinion. The width of the grooves corresponds essentially with that of the tooth gaps or teeth, respectively, so that neighbouring tooth gaps are not overlapped.

A still further advantageous embodiment of the gear pump is shown in a longitudinal section view in Figure 8. Here, housing plate 1 is a ring with a smooth, circular-cylindrical inner bore serving as interior 30. Rotor 22 carrying the journals 24 for pinions 8 is mounted on its drive shaft 28 rotationally secured by an adjusting spring 53, but adapted to be axially displaced. A stationary gear 31 with an external toothing 32 is held in place in housing 1 by means of bores 50 distributed over its circumference, into which bores locking pins 51 located in housing cover 3 engage.

Between the stationary gear 31 with pinions 8 meshing therewith and the inside wall of the housing cover 3, a valve plate 41 is provided which rotates synchronously together with rotor 22 and pin ions 8. It contains for each pinion 8 a valve bore 42 which extends on a straight line connecting the rotor axis with the respective pinion axis. Its distance from the rotor axis is do dimensioned that the valve bores 42 extend beyond the tooth gap sections between pitch circle 47 and dedendum circle 48 of the external gear 31.

The outlet ducts for the pumped fluid are accommodated in housing cover 3. They start at their inlets 40 which are arranged in the side of the housing cover 3 facing valve plate 41, form a circle 44 coaxial to rotor 22, and are located opposite to the tooth gaps 36, with the diameter of circle 44 ranging between that of the dedendum circle 48 and pitch circle 47 of external toothing 32. They extend with their portion 43, up to the centre of housing cover 3, parallel to the rotor axis, and from there radially outwardly.To minimize leakage losses, when the pumped fluid is transferred from the tooth gaps 36 through valve bore 42 into the inlets 40 of the outlet ducts, the rotor 22, pinions 8, stationary gear 31 and valve plate 41 may advantageously be axially displaceable relative to housing 1 and the rotor axis, and be pushed by a pressure spring 45 supported in an abutment 52 against the inside wall of housing cover 3 with outlet ducts 1 5. Journals 24 carrying pinions 8 are so dimensioned that they extend into corresponding bores of valve plate 41, and thus non-rotationally connect the same with the rotor.

In the circumferential direction, the width of valve bore 42 corresponds substantially to that of the tooth gaps or teeth so that neighbouring teeth are not overlapped.

The gear pumps described and illustrated are particularly suitable for an intermittent supply of a large number of similar users.

Each of these users is supplied, at each rotation of the rotor 22, with a constant quantity of fluid as many times as there are pinions 8 present on the circumference of the rotor.

Prerequisite for a satisfactory operation is that the toothing of the stationary gear and of the pinions is so shaped that, as soon as a pinion tooth 35 moves into a tooth gap 36 of the stationary gear, the respective tooth gap, which was filled from the fluid-filled interior space 30 before the entry of the tooth, remains sealed against its surroundings, so that the enclosed quantity of fluid can only escape into outlet ducts 1 5.

Figures 9 and 10 show possible constructions of the toothing. The toothing in Figure 9 is so designed that the flanks of each tooth of the rotating gear contact, at the working depth, the flanks of the stationary gear (here internal gear), substantially free from play, and-taking into account the viscosity of the medium to be pumped and metered-form a seal. Thus, during the course of an engagement, each tooth gap forms a pump and metering chamber of a reducing volume.

In the tooth arrangement of Figure 10-il- lustrating a stationary external gear and a pinion meshing with the same-two successive teeth contact the others with their flanks facing each other. A precondition therefor is that the degree of overlap is greater than two.

Under this condition, such a toothing can still be produced by the self-generating method.

When the degree of overlap is greater than three, only profiled tooth construction will meet the requirements. The tooth gaps of the stationary gear will then form with the tooth gaps of the rotating gear S-shaped cells the volume of which varies during the engagement.

The housing of the pump as per Fig. 11 consists of two housing plates 1, an intermediate plate 4 and the front plates 2 and 3.

Shaft 28 is rotatably mounted within front plate 2. Liquid inlet 1 2 is in front plate 3.

Two rotors 9 and in intermediate disc 22 are fixedly mounted to a shaft 28 to rotate therewith. Gears 8 are freely rotatably mounted on bolts 24 to mesh with the teeth of each of the housing plates 1. The diameter of the intermediate disc 22 may be greater than the diameter of the outer circle of the teeth of the housings 1 so as to cover the gaps between those teeth. The diameter of the inner wall of intermediate plate 4 is slightly greater than that of the outer circle of the teeth, so that a groove is formed between those housing plates 1 which the intermediate plate 22 protrudes into. However, it is also possible to cover these gaps by the intermediate plate 4.

The shape of the rotors with the gears is the same as shown, e.g., in Figs. 1, 1A, 18.

By this pump arrangement, the number of liquid streams can be doubled.

The pump shown in Fig. 1 2 has a housing which also consists of two housing plates 1, an intermediate plate 4 and the front plates 2 and 3. There is only one rotor 9 on both sides of which are pockets to receive gears 8 which are in meshing engagement with the teeth of the housing plates 1. In all other respect, this pump corresponds to that one shown in Fig.

11.

In Figs. 11 and 12, bores are shown in dotted lines which are provided to connect grooves 14 on both sides of the rotor for supply of fluid from fluid inlet 1 2 to the other side.

NUMERAL REFERENCE LIST 1 Housing plate, housing 2 Housing cover 3 Housing cover 4 Additional plate 5 Addendum circle 6 Internal gear, internal toothing, internal tooth rim 7 Pocket 8 Pinion 9 Rotor disk, rotor, rotor plate 10 Circle of centers 11 Dedendum circle 12 Fluid inlet, entry, supply 13 Tap line 14 Annular duct 1 5 Outlet duct [discharge duct] 1 6 Angular distance 1 7 Sector angle 1 8 Corner, boundary 1 9 Corner, boundary 20 Return flow stop 21 Cylindrical outside surface, outside circumference 22 Rotor, bearing plate 23 Cylindrical bore 24 Journal 25 Cylindrical recess, distributor 26 Front side 27 Rotary direction, rotational direction of rotor 28 Drive shaft 29 Pitch circle 30 Interior, inner space 31 External gear, 32 External toothing 33 Tooth flank 34 Tooth flank 35 Tooth, pinion tooth 36 Tooth gap 37 Flank 38 Flank 39 Groove, radial groove 40 Inlet to outlet [discharge] duct, inlet 41 Valve plate 42 Valve bore 43 Section [portion] of outlet duct, portion 44 Circle, circle of inlets 45 Pressure spring 46 Dedendum width 47 Pitch circle 48 Dedendum circle 49 Addendum circle 50 Bore 51 Locking [retaining] pin 52 Abutment 53 Adjusting spring 54 Gear cover [overlap]

Claims

1. An apparatus for producing a large number of identical, independent (small-volume) streams of liquid, comprising a gear pump, the pump housing of which has an internal toothing in which at least one pinion guided by a rotor engages, a supply of fluid which leads to the interior defined by the addendum circle of the internal toothing, and outlet ducts proceeding from the internal toothing which are secured by return flow stops.

2. A gear pump according to claim 1, wherein the rotor has a circular-cylindrical outer surface which is adapted to the interior of the pump housing defined by the addendum circle of the internal toothing, and has at least one circular-cylindrical pocket to take up one pinion meshing with the internal toothing.

3. A gear pump according to claim 1 or 2, wherein the angular distance between two neighbouring outlet ducts is not larger than half of the sector angle of the pocket opening on the rotor circumference allowing the passage of the meshing teeth of the pinion.

4. A gear pump according to any preceding claim, wherein the pinion of pinions are floating supported in the pocket or pockets of the rotor.

5. A gear pump according to any preceding claim, wherein the pump rotor consists of two or more individual rotors with pockets, wherein the pockets of all individual rotors have the same angular distance from each other, when jointly projected on a plane parallel to the individual rotors, wherein neighbouring individual rotors are separated from each other by concentric, circular discs, the outer diameter of which is greater than the diameter of the dedendum circle of the internal toothing, and wherein the circular discs move into intermediate grooves so as to separate the individual working areas, which grooves are provided in the internal toothing extending across the width of the composite rotor.

6. A gear pump according to any of claims 1 to 3, wherein the pump housing consists of plate provided with an internal toothing and an additional plate having a smooth bore concentric with the internal toothing, wherein pinions rotate about journals which are mounted on a bearing plate concentric with and connected to the rotor, and wherein a bearing plate moves in the smooth, cylindrical bore of the additional plate of pump housing.

7.-A gear pump according to claim 6, wherein two or more pump housings with rotors and bearing plates as well as pinions rotating about journals are coaxially juxtaposed without interspace, and pinions are, as a whole, evenly distributed over the circumference.

8. A gear pump according to claim 6, wherein the additional plate is arranged between two housing plates and pinions of both housing plates are supported in journals which are mounted on the bearing plate moving in the additional plate, and which are, in their entirety, evenly distributed over the circumference thereof.

9. A gear pump according to any preceding claim, wherein the pump housing is circularcylindrical and wherein outlet ducts extend radially outwardly at an identical angular distance from each other.

10. A gear pump according to any preceding claim, wherein the drive shaft of the rotor is supported in one of the two housing covers, wherein the housing cover possesses an inlet and a distributor from the pumped fluid being connected to the same, and wherein an annular duct is connected with the inlet via the distributor.

11. A gear pump according to any of claims 6 to 10 as dependent on claim 1, wherein each pinion rotating about a journal of the bearing plate is provided on its front side, as seen in the rotary direction of the rotor, with a tooth cover which adjoins, in the area where the pinion teeth mesh internal toothing both the addendum circle of the pinion and the addendum circle of internal toothing, and which tooth cover is again connected with the rotor or the bearing plate.

1 2. A gear pump according to claim 11, wherein the tooth cover overlaps at least one to one and one half tooth pitches both at the rim of the internal toothing and the pinion toothing.

1 3. A gear pump according to any of the foregoing claims, wherein the housing cover with the inlet for the pumped fluid possesses on its inner side a circular-cylindrical recess, wherein an annular duct in the rotor faces the said recess the diameter of which is not smaller than the largest diameter of the annular duct, and wherein the circular-cyclindrical recess and the annular duct have a joint axis.

14. A gear pump according to any of the foregoing claims 6 to 11, wherein the outlet ducts are ducts which proceed from the front side of the housing plate opposite to bearing plate and are paraxially arranged on a circle, said circle being larger by at least twice the diameter of the inlets to the outlet ducts than the diameter of the dedendum circle of the internal toothing, with the bearing plate having on its side facing front side a grooveshaped recess extending to each pinion, which groove-shaped recess overlaps, in the radial direction, the area between the inlets of the paraxial outlet ducts and the addendum circle of the internal toothing and extends in circumferential direction over a sector angle which is smaller by the diameter of an inlet to an outlet duct than the angular distance of the neighbouring outlet ducts, with the beginning of the groove-shaped recess, as seen in the rotary direction of the rotor, corresponding to that corner of the pocket opening on the rotor circumference which comes, in the rotary direction of the rotor to lie in front.

1 5. A gear pump according to any of the foregoing claims, wherein the rotor has an annular duct which engages with the inlet in one housing cover and intersects the pockets.

1 6. A gear pump according to claim 1, wherein the annular duct is connected with the rotor circumference by radially extending tap lines.

1 7. A metering gear pump with a stationary gear and a rotating gear engaging therewith, in particular according to claim 1, wherein in a fluid-filled interior with a fluid inlet, at least one gear eccentrically rotatably supported on a rotor rotates and meshes with the stationary gear in concentric relationship with the rotor, wherein the toothing of the stationary and of the rotating gear are such that the teeth of the rotating gear respectively close, together with the housing front walls, a tooth gap of the stationary gear like cell, and wherein there is associated with each tooth gap of the stationary gear an outlet duct which is opened for the discharge of a metered quantity of fluid, by a non-return valve, or by a slot regulating mechanism which is actuated by the rotor.

1 8. A metering gear pump according to claim 17, wherein the toothing is such that each tooth moving into a tooth gap comes into contact with the two teeth surfaces defining the tooth gap of the stationary gear, and closes the tooth gap like a cell taking into account the viscosity of the metered medium.

1 9. A metering gear pump according to claim 17, wherein the toothing is so designed that the degree of overlap is greater than two.

20. A metering gear pump, according to any of the foregoing claims, wherein the stationary gear is designed and constructed as an internal gear ring which forms the circumfer ential wall of the interior.

21. A gear pump according to any of claims 1 7 to 20, wherein the stationary gear is an external gear concentric to the circularlycylindrical interior.

22. A gear pump according to any of the foregoing claims, wherein the outlet ducts extend, in the housing cover, with their first section being in alignment with each tooth gap of the stationary gear.

23. A gear pump according to claim 22, wherein there is arranged between the stationary gear and the housing cover a valve plate actuated synchronously with the rotor which valve plate contains a bore essentially engaging with the first duct sections in the joint axial plane of the rotor axis and pinion axis.

24. A gear pump according to claim 23, wherein the valve plate is located on the same drive shaft as the rotor, and by means of which the rotating gear accommodating the journals is non-rotatingly connected with the rotor.

25. A gear pump according to any of claims 17 to 21, wherein each of the outlet ducts begins with a first section which extends parallel, respectively, to a tooth gap in the stationary gear, and wherein the rotor overlapping the stationary gear on its front side is designed as a valve plate with a radially directed recess, with the recess respectively engaging with a tooth gap and the associated first section of the outlet duct.

26. A gear pump according to claim 25, wherein a recess essentially extends in the joint axial plane of the rotor axis and the axis of the rotating gear.

27. A gear pump according to any of claims 23 to 26, wherein the rotor, the rotating gears, the stationary gear and valve plate are axially displaceable relative to the housing and the rotor axis, and are pushed against the housing cover containing the outlet ducts by means of a pressure spring.

28. A metering gear pump according to any of the foregoing claims, wherein the rotating gear is supported on a shaft of the rotor which projects into the interior.

29. A gear pump according to any of claims 1 7 to 28, wherein the rotor or rotor disc axially projects into the interior and has recesses to the floating bearing support of the pinions, with the recesses extending through the outside surfaces of the rotor.

30. A gear pump according to any of the foregoing claims, wherein the fluid inlet is arranged in the housing cover which is located on the side of the housing plate turned away from the rotor.

31. A gear pump according to claim 30, wherein housing cover with the fluid inlet possesses on its inner side a circular-cylindrical recess which overlaps the circle along which the axis of pinion rotates, but is smaller than the addendum circle of the stationary internal gear.

32. An apparatus for producing a large number of identical, independent streams of liquid substantially as herein described and as illustrated in the accompanying drawings.

33. A gear pump substantially as herein described and as illustrated in the accompanying drawings.