EP2235374B1 - Variable-volume internal gear pump - Google Patents

Abstract

The invention relates to a variable-volume internal gear pump, in particular for use as an engine lubrication pump for automobiles. The internal gear pump comprises a housing (7, 10) and a rotor set chamber (40) formed therein comprising a low pressure chamber (17) and a high pressure chamber (18) for a fluid. Inside the rotor set chamber (40) are an inner rotor (2) that can be rotatably driven by a shaft (1) about an axis of rotation (Di) and a rotatable outer rotor (3) with an outer rotor axis of rotation (Da) that is arranged eccentric with respect to the axis of rotation (Di). When a rotational force is applied, conveyance cells (30, 31) form between the inner rotor (2) and the outer rotor (3) in which the fluid is conveyed from the low pressure chamber (17) to the high pressure chamber (18). An adjusting member (5) upon which axial springs (8) act and which is guided in the internal gears (34) of the outer rotor (3) in axial motion causes a pressure-related axial movement of the inner rotor (2). The outer rotor (3) comprises radial channels (41) in the gaps between the teeth of the internal gears (34) thereof proximate to the low pressure chamber (17) and the high pressure chamber (18). The axial position of the inner rotor (2) relative to the outer rotor (3) can be adjusted by the axial motion of the adjusting member (5), whereupon the volume of the conveyance cells (30, 31) changes depending on the pressure.

Description

The invention relates to an internal gear pump, in particular for use as a motor lubricating pump for automobiles, according to the preamble of claim 1.

Because of the demand for the lowest possible power losses over the entire engine speed and power range, the engine designer increasingly demands that the oil delivery of the pump no longer increase proportionally with the engine speed as before. The lubricating oil demand curve of the engine has a degressive characteristic over the course of the engine speed. This means that the engine does not have any lubrication oil requirement that is proportional to the speed. Thus, this is much smaller at increased speed.

For non-controllable pumps, the lubricating oil flows back to the suction side of the pump from a certain maximum oil pressure via a bypass valve. This results in a considerable loss of hydrostatic power, which is largely avoided by an automatically controlled pump demand-oriented. Namely, this loss develops exponentially at a constant specific delivery rate of the pump, because in addition to the delivery rate over the speed also increases the oil pressure. This situation also has another aspect: When the engine is cold and thus with extremely viscous lubricating oil, the oil pressure, despite the bypass valve, assumes inadmissibly high values, so that, in particular, the main flow filters of the engine are endangered. In addition, the aging of the oil increases when it is extremely strained by a large proportion of time through the narrow gaps of the system and with high pressure difference at high shear rate. There are already adjustable in their specific flow rate Engine lubrication pumps are known, with more or less unwanted by-products.

A known volume changeable internal gear pump regulates the specific delivery rate in that oil pressure dependent the center distance line of the gear set is rotated relative to the suction and pressure chambers in the pump housing. However, this has two major disadvantages, namely that with regulated pump unavoidable crushing caused by this so-called differential control and the pump thereby develops strong noise at high speed. In addition, the crush losses reduce the mechanical efficiency of the pump in this operating range. In addition, the crushing losses cause considerable pressure peaks between the teeth, whereby the components are additionally burdened and the life is reduced.

Another solution is known as a kind of vane pump or "pendulum wing pump", wherein in a known manner, the eccentricity of the winged rotor with respect to the housing ring is changed. This has a relatively large number of filigree small components that are fragile and expensive to manufacture.

Finally, an external gear pump is still known in which the effective tooth width of the pump is reduced with increasing pressure by axial displacement of the two gear wheels. Since these gears must be made relatively wide, and the pump housing with its spectacle-shaped inner contour must have a corresponding length. This leads to high production costs in the housing cavern processing. In addition, external gear pumps are because of their high delivery pulsation and because of their radial filling on the suction side cavitation and thus sensitive to noise.

From the US 2,484,789 which is regarded as the closest prior art, the US 6,244,839 and the JP 56 047692 Are also known volume variable internal gear pumps or motors, in which the volume variability can be effected by adjusting the axial position of an inner rotor relative to an outer rotor by an axial movement of an adjusting. Due to the structural design of these pumps, however, it is not possible to make the specific flow in a structurally simple way pressure-dependent, in particular with increasing pressure, the volume of the pump and thus also the specific flow rate decreases.

The invention has as its object to provide a variable in their specific flow pump, in particular a motor lubricating pump, which avoids these disadvantages in a comprehensive manner.

This object is achieved by the realization of the features of the independent claim. Features which further develop the invention in an alternative or advantageous manner can be found in the dependent claims.

The invention comprises a volume-variable internal gear pump. The advantage of an internal gear pump over other engine lubrication pumps that can be regulated in their specific delivery rate is, in particular, that, on the one hand, an internal gear pump is superior in terms of noise because of its small instantaneous delivery pulsation over the rotational angle of the gear wheels of the external gear pump. In addition, it can be carried out with small numbers of teeth at the same time extremely centric design. Both result in low meshing frequency and low hydraulic Pressure pulsations. Because of the possible large eccentricity of the moving set arise very large-volume conveyor cells that lead to required radial displacement of the pump at required displacement. At the same time the exact internal machining of the pump housing is very simple, because basically only circular, easily representable on the lathe manufacturing operations are necessary.

The inventive variable volume internal gear pump comprises a housing and a moving set chamber formed in the housing and having a low pressure chamber with an inlet port and a high pressure chamber with an outlet port for a fluid. An inner rotor accommodated in the travel set chamber is rotatable about an axis of rotation and can be driven by a shaft. In the motion chamber an outer rotor is rotatably received with an eccentric to the rotation axis arranged outer rotor axis of rotation. The inner rotor has such Außenvergütung and the outer rotor has such an internal toothing that the outer rotor with the inner rotor by the outer internal teeth can rotate in a constant rotational relationship to each other and forms in the case of a rotary drive conveyor cells in which the fluid from the low pressure chamber to the high pressure chamber promoted becomes.

According to the invention an adjusting member is provided which causes an axial movement of the inner rotor. The adjusting member is axially movably guided in the internal toothing of the outer rotor. The outer rotor has in its tooth gaps of the internal teeth in the region of the low pressure chamber and the high pressure chamber arranged radial channels. The axial position of the inner rotor relative to the outer rotor is variable by the axial movement of the adjusting, so that in this way the volume of the delivery cells can be adjusted and an adjustable in their specific flow rate internal gear pump is provided.

In particular, the delivery volume and the specific delivery rate of the internal gear pump is pressure-dependent, with increasing pressure from the outlet opening and thus with increasing pressure in the high-pressure chamber, the volume of the delivery cells and thus the specific delivery rate decreases.

The external toothing of the inner rotor has such a shape that axially effective springs, in particular helical springs, can be installed between the shaft driving the inner rotor and the tooth contour of the outer toothing and arranged there.

Preferably, the springs, which act axially on the adjusting member, are arranged in the inner rotor between the shaft driving the inner rotor and the tooth contour of the outer toothing. A connected to the high-pressure chamber adjustment, which is bounded axially by the adjusting member is formed within the internal toothing of the outer rotor, so that a pressure of the fluid within the adjustment chamber acts axially on the adjusting member against the spring force of the springs. The opposite arrangement of the associated with the high-pressure chamber and thus the outlet opening adjusting chamber, the pressure of the fluid from one side acts on the adjusting member, and the spring force, which presses from the other side on the adjusting member, wherein the conveyor cells are interposed, causes in that, as the pressure in the high-pressure chamber increases, the adjusting member is displaced counter to the spring force of the springs and the volume of the delivery cells is reduced.

These springs are supported for example via a cup-shaped intermediate member and a locking ring in the axial direction of the shaft. In particular, three springs, in particular helical springs, are uniformly distributed in the inner rotor on the circumference.

The commutation of the change of the oil flow from the - also referred to as suction chamber - low pressure chamber to - also called pressure chamber - high pressure chamber and again from the pressure chamber to the suction takes place in a gentle manner on the outer rotor with its communicating with the housing radial channels, so here any squeezing the fluid, in particular the oil, is largely avoided in the delivery cells. The possibility of accurate circular bore in the pump housing for the storage of the outer rotor and the preferably as possible to be observed separation webs between the suction and pressure chamber allow this precise commutation.

In a further development of the invention, the adjusting member has an external toothing, which fits with sufficient but small running clearance of the internal toothing of the outer rotor and thus is sealingly axially movable therein.

The geometrical shape of the external internal toothing, that is, the external payment of the internal rotor and the internal toothing of the external rotor assigned to it, is formed, for example, as an epicycloidal or arcuate external toothing on the internal rotor, which generates the internal toothing of the external rotor with one tooth by a generator rolling movement. The outer toothing of the inner rotor thus has one tooth less than the inner toothing of the outer rotor. The generator principle, also called production rolling, in which a parent profile is passed in a counter-wheel, while maintaining the eccentricity and the rotational ratio is known from the gearing and need not be explained in detail. The person skilled in the art is aware that other geometric designs, as known from the prior art in gear pumps, in particular an epicyclic outer toothing, are possible. For example, the geometric shape of the external internal teeth can be determined by epi- and hypocycloids.

The external toothing of the inner rotor has, for example, between 5 and 8 teeth, in particular 6 teeth.

In one embodiment of the invention, the inner rotor is disposed on the shaft driving it axially movable and rotationally secured substantially without impact. The rotationally secured axially movable arrangement takes place for example by means of a feather key.

The feed cells are preferably closed in the axial direction and in opposition to the adjusting member by a pinion plate whose internal teeth fit with sufficient but small running clearance of the outer toothing of the inner rotor such that the inner rotor is axially movable within the internal toothing of the pinion plate. At the pinion plate, a blading corresponding to a centrifugal pump is preferably arranged or formed. This blading corresponding to a centrifugal pump is in particular a Axialbeschaufelung. By means of this blading, the pump is charged on the suction side, so that with increasing speed, the fluid pressure in the suction chamber increases approximately with the square of the speed. Thus, this pump is according to the invention for extremely high speeds because of the avoidance of Cavitation bubbles in the oil. This too leads to small footprint of the pump in the engine.

Between the housing and an outside of the housing arranged on the shaft drive wheel can be provided on the drive side acted upon by the high pressure, the axial forces balancing compensation pressure range acting as a compensation surface. Alternatively, this is acted upon by the high pressure, the axial forces balancing compensation pressure range on the drive side opposite side between the housing or a lid of the housing and the cup-shaped intermediate member. In both cases causes the compensation pressure range, which is connected to the high pressure area or the high pressure chamber, that counteracts a hydraulic pressure force in the compensation pressure range of the hydraulic pressure force also acted upon by high pressure displacement.

Figur 1

eine Ausführungsform der Innenzahnradpumpe in einem Längsschnitt durch die Wellenmitte und die Innenrotormitte der Pumpe bei maximaler spezifischer Fördermenge;

Figur 2

einen gleichen Längsschnitt bei minimaler spezifischer Fördermenge;

Figur 3

einen Querschnitt durch die Pumpe entlang der Schnittlinie A-A der Figur 1;

Figur 4

einen Längsschnitt durch die Wellenmitte und die Innenrotormitte entlang der Schnittlinie B-B der Figur 3 bei maximaler spezifischer Fördermenge;

Figur 5

einen gleichen Längsschnitt bei minimaler spezifischer Fördermenge;

Figur 6

einen Querschnitt entlang der Schnittlinie C-C der Figur 1;

Figur 7

eine Darstellung der Ritzelplatte mit der darauf befestigten Axialbeschaufelung für die axiale Kreiselpumpe;

Figur 8

eine Darstellung des Verstellorgans;

Figur 9

eine alternative Ausführungsform der Innenzahnradpumpe mit einem alternativen Kompensationsdruckbereich in einem Längsschnitt bei maximaler spezifischer Fördermenge;

Figur 10

einen gleichen Längsschnitt bei minimaler spezifischer Fördermenge; und

Figur 11

eine Darstellung des als Kronenrad ausgebildeten Aussenrotors der alternativen Ausführungsform.

In the drawings, the subject invention is shown purely by way of example with reference to concrete embodiments. Show it:

FIG. 1

an embodiment of the internal gear pump in a longitudinal section through the shaft center and the inner rotor center of the pump at maximum specific flow rate;

FIG. 2

a same longitudinal section with a minimum specific flow rate;

FIG. 3

a cross section through the pump along the section line AA of FIG. 1 ;

FIG. 4

a longitudinal section through the shaft center and the inner rotor center along the section line BB of FIG. 3 at maximum specific flow rate;

FIG. 5

a same longitudinal section with a minimum specific flow rate;

FIG. 6

a cross section along the section line CC of FIG. 1 ;

FIG. 7

a representation of the pinion plate with the attached Axialbeschaufelung for the axial centrifugal pump;

FIG. 8

a representation of the adjusting member;

FIG. 9

an alternative embodiment of the internal gear pump with an alternative compensation pressure range in a longitudinal section at maximum specific flow rate;

FIG. 10

a same longitudinal section with a minimum specific flow rate; and

FIG. 11

a representation of the formed as a crown wheel outer rotor of the alternative embodiment.

Because the FIGS. 1 to 8 illustrate a common embodiment of the invention in different views, details and levels of detail, the FIGS. 1 to 8 essentially described together.

FIG. 1 shows the variable volume internal gear pump in a longitudinal section through the shaft center and the Inner rotor center of the pump at maximum specific delivery rate. The internal gear pump has a two-part housing, which is composed of the actual housing 7 and a cover 10 of the housing, which are interconnected by means of screws 19. In the housing 7, a running set chamber 40 is formed, which has a low pressure chamber 17 with an inlet opening 15 and a high pressure chamber 18 with an outlet opening 16 for a fluid. In the motion chamber 40, an inner rotor 2 is accommodated, which is rotatable within the motion chamber 40 of the housing 7 about a rotational axis Di and by a shaft 1, which is passed through the housing 7 and the cover 10, driven. The inner rotor 2 is axially movable on the shaft 1 driving it, but is secured against rotation by a feather key 11 substantially without impact. In the motion chamber 40 is also an outer rotor 3 rotatably received with an eccentric to the rotational axis Di arranged outer rotor axis of rotation Da, as in the Figures 3 . 4 and 6 recognizable. The inner rotor 2 has such Außenverzahlung 33 - namely with 6 teeth - and the outer rotor 3 such internal teeth 34 - namely with 7 teeth - on ( FIGS. 1 and 3 ) that the outer rotor 3 rotates with the inner rotor 2 through the outer internal teeth 33, 34 in a constant rotational ratio and in the case of a rotary drive conveyor cells 30, 31 (FIG. FIGS. 1 and 3 ), in which the fluid from the low pressure chamber 17 to the high pressure chamber 18 (FIG. FIGS. 1 and 3 ). The outer rotor 3 has in its seven tooth gaps of the internal teeth 34 in the region of the low pressure chamber 17 and the high pressure chamber 18 arranged radial channels 41 (FIGS. FIG. 2 . 3 and 5 ).

In the FIGS. 1 . 2 and 5 an inventive adjusting member 5 is shown, the axial movement of the Inner rotor 2 causes. The adjusting member 5 is axially movably guided in the internal toothing 34 of the outer rotor 3, wherein the adjusting member 5 has an external toothing 34a, which corresponds exactly with sufficient, but small running clearance of the internal toothing 34 of the outer rotor 3 and thus sealingly therein is axially movable. FIG. 8 shows the adjusting member 5 with its external teeth 34a in a detailed view. The axial position of the inner rotor 2 relative to the outer rotor 3 is adjustable by the axial movement of the adjusting member 5, whereby the volume of the feed cells 30, 31 is variable.

Evenly distributed in the inner rotor 2 are three axially acting coil springs 8 between the inner rotor 2 driving shaft 1 and the tooth contour of the external teeth 33 installed as in the FIGS. 1 . 3 and 6 recognizable. For this purpose, the external teeth 33 of the inner rotor 2 has a corresponding shape. The three coil springs 8 are connected via a cup-shaped intermediate member 6 (FIG. FIGS. 1 and 5 ) and a locking ring 12 ( FIG. 1 ) supported in the axial direction on the shaft 1.

The conveyor cells 30, 31 are in the axial direction and in opposition to the adjusting member 5 by a pinion plate 4 and 46, which in FIG. 1 recognizable and in detail in FIG. 7 shown is closed. The internal teeth 32 of the pinion plate 4 and 46 corresponds exactly fitting with sufficient, but small running clearance of the external teeth 33 of the inner rotor 2 such that the inner rotor 2 within the internal teeth 32 of the pinion plate 4 and 46 is axially movable. On the pinion plate 4 and 46 is a centrifugal pump 21 ( FIG. 1 ) corresponding blading 42 ( Figures 5 and 7 ) arranged.

The direction of rotation of the moving set of the pump to explain the function in the individual figures in the specified Arrow direction 43 ( FIG. 3 ), 44 ( FIG. 6 ) and 45 ( Figures 5 and 7 ), so that the respective suction and pressure side is given clearly according to the expanding and compressing conveying cells of the teeth. In the cover 10 of the intake manifold on the inlet opening 15, which forms the suction opening arranged. A suction chamber 20 surrounds the cup-shaped intermediate member 6 and is at the same time the suction side of the blading 42 of the axial centrifugal pump 21. The pressure side of this axial centrifugal pump 21 is also acting as a suction low pressure chamber 17 of the internal gear pump. About the radial channels 41 of the outer rotor 3, the oil is sucked into the expanding conveyor cells 30 against the centrifugal force. The axial impeller of the centrifugal pump 21 runs in the pump shown in the drawing in proportion of the number of teeth of the moving set by a factor of 7: 6 faster than the outer rotor 3, so that the centrifugal pressure in the radial channels 41 of the outer rotor 3 by the pumping pressure of the centrifugal wheel of the centrifugal pump 21st more than balanced. With increasing speed of the axial centrifugal pump 21 on the pinion plate 4 and 46 according to FIG. 7 the pressure in the suction chamber 17 is constantly greater, so there is a vapor and air bubbles in the oil and the associated risk of cavitation is excluded even at high speeds. The same applies to the suction-side delivery cells 30.

The compressing conveyor cells 31, see FIG. 3 , displace the oil into the high-pressure chamber 18 to the outlet opening 16.

In the FIG. 1 the moving set has the maximum tooth width when the coil springs 8 are able to push the inner rotor 2 and thus the adjusting member 5 completely to the left until the approximate stop on the housing 7. This is the case when in the adjustment space 25, clearly shown in the FIG. 2 , a very low pressure prevails. It is expedient that the coil springs 8 are prevented by a snap ring 13 from axially pressing the adjusting member 5 to the housing 7, so at zero pressure, ie idle, no unnecessary loss of friction arises. The distance between this snap ring 13 and the circlip designed as a circlip 12, both fixed on the shaft 1, should be chosen so that between the package, consisting in particular the adjusting member 5, the inner rotor 2, the coil springs 8, the cup-shaped intermediate member. 6 and the pinion plate 4, 46 is still a sufficient axial clearance between the adjusting member 5 and the housing 7 is present.

If this internal gear pump is now shot on the high pressure side at the outlet opening 16 to the lubricating oil circuit, for example, an internal combustion engine, then increases according to the engine's slip curve with increasing engine and thus (at rigid drive) pump speed of the oil pressure in the high pressure chamber 18. About channels 23 and 24th in the FIG. 2 can be clearly seen, this high pressure also prevails in the adjustment 25 and moves depending on the height of the speed and thus the high pressure, the adjusting member 5 and with him the inner rotor 2 against the spring force to the right. However, the outer rotor 3 retains its axial position, due to the small axial play between the housing 7 and the pinion plate 4 and 46. The effective tooth width of the moving set is thereby reduced and the specific delivery rate is reduced, as in FIG. 2 illustrated.

The hydraulic pressure force in the adjustment chamber 25 on the adjusting member 5 and thus on the inner rotor 2 on the coil springs 8 and the cup-shaped intermediate member 6 and also on the axial surface of the outer rotor 3 via the pinion plate 46, 4 is based on the locking ring 12 on the shaft first So that the locking ring 12 or the cup-shaped intermediate member 6 does not start on the cover 10 at the shaft bearing 27 with great force, is arranged on the drive side between an outside of the housing 7 on the shaft 1 arranged drive wheel 9 (FIG. FIG. 1 ) and the housing 7, a compensation pressure region 22 is provided, which from the high pressure via the channel 23 (FIG. FIG. 2 ) is applied. This compensating pressure region 22 is dimensioned such that its exerted axial force on the shaft 1 via a central screw 14 to the left in the FIG. 1 slightly smaller than the total hydrostatic axial force of the rotor system to the right. As a result, the lubrication and cooling of the compensating pressure region 22 to the outside closing annular Abdichtfläche 47 between the drive wheel 9 and the housing 7 can be optimized.

The in the FIGS. 9 to 11 shown alternative embodiment of the internal gear pump corresponds in essential parts in the FIGS. 1 to 8 illustrated embodiments of the internal gear pump, which is why in the following partly only the essential distinction is received.

The alternative embodiment of the internal gear pump has the housing 7 with the cover 10 belonging to the housing. In the housing is provided the running set chamber 40, which has the low pressure chamber 17 with the inlet opening 15 and the high pressure chamber 18 with the outlet opening 16 for a fluid. The inner rotor 2, which is rotatable about the rotational axis D _i and can be driven by the shaft 1, is accommodated in the travel set chamber 40. The rotatably received in the motion chamber 40 outer rotor 3a has an eccentric to the rotational axis D _i arranged outer rotor axis of rotation. The inner rotor 2 has such Außenverzahlung 33 and the outer rotor 3a such an internal toothing 34 that the Outer rotor 3a rotates with the inner rotor 2 through the outer internal teeth 33, 34 in a constant rotational ratio and in the case of a rotary drive, the delivery cells 30, 31 forms, in which the fluid from the low pressure chamber 17 to the high pressure chamber 18 is promoted. By means of the axially movable in the internal teeth 34 of the outer rotor 3 performed adjusting 5 is an axial movement of the inner rotor 2 effected. The axial position of the inner rotor 2 relative to the outer rotor 3a is variable by the axial movement of the adjusting member 5, so that the volume of the feed cells 30, 31 can be changed. FIG. 9 shows the internal gear pump at maximum specific flow and FIG. 10 at minimum specific flow rate. The external teeth 33 of the inner rotor 2 has a shape such that the axially effective springs 8 between the inner rotor 2 driving shaft 1 and the tooth contour of the external teeth 33 place. With regard to these features, the alternative embodiment of the internal gear pump corresponds to Figures 9 and 10 that embodiment of the FIGS. 1 to 8 ,

The outer rotor 3a has in its tooth gaps of the internal teeth 34 in the region of the low pressure chamber 17 and the high pressure chamber 18 also radial channels 41a, but these radial channels 41a are not formed as radial holes in the middle of the outer rotor 3a, as in the first embodiment and as in FIG. 1 recognizable, but the radial channels 41a are located as slot-like radial recesses on the edge of the outer rotor 3a. In other words, the outer rotor 3a is formed as a crown wheel, as in the FIG. 11 shown in a single front view and a single side view. An advantage of this arrangement is the easier manufacture of the radial passages 41a. In addition, an annular intermediate plate 50 is provided between the cover 10 and the rest of the housing 7, which has openings for the channels, wherein the hole pattern substantially corresponds to the hole pattern of the housing 7.

The springs 8 are also supported via a cup-shaped intermediate member 6a and a locking ring 12 in the axial direction of the shaft 1, however, the cup-shaped intermediate member 6a has such - in particular cylindrical - outer shape that the intermediate member 6a radially sealing the cover 10 of the housing. 7 touched. For sealing a piston ring 48 is provided for this purpose. Thus, between the cup-shaped intermediate member 6a and the cover 10 of the housing 10, a between the housing 10 and the cup-shaped intermediate member 6a from the high pressure acted, the axial forces balancing compensation pressure area 22a formed. In order to pressurize the compensation pressure region 22a with high pressure, a channel 49 is provided, which connects the compensation pressure region 22a with the high-pressure chamber 18. This compensating pressure region 22a is also dimensioned such that a hydraulic pressure force in the compensation pressure region 22a counteracts the hydraulic pressure force in the adjusting chamber 25, which is also subjected to high pressure. In other words, the compensation pressure area 22a in this embodiment has been viewed from the side of the drive wheel 9, FIG. 1 , relocated to the opposite side. This has the particular advantage that the drive wheel 9 in the embodiment of the FIGS. 9 to 11 has no sealing function and can be easily replaced with another drive wheel 9 on the shaft 1.

Claims (16)

1. Variable-volume internal gear pump, which comprises

   • a casing (7, 10),

   • a rotor assembly chamber (40) which is formed in the casing (7) and which has a low-pressure chamber (17) with an inlet port (15) and a high-pressure chamber (18) with an outlet port (16) for a fluid,

   • an inner rotor (2) which is received in the rotor assembly chamber (40) and which is rotatable about an axis of rotation (Di) and is drivable by a shaft (1), and

   • an outer rotor (3) received rotatably in the rotor assembly chamber (40) and having an outer rotor axis of rotation (Da) arranged eccentrically with respect to the axis of rotation (Di), the inner rotor (2) having such external toothing (33) and the outer rotor (3) such internal toothing (34) that the outer rotor (3) rotates in a constant ratio of rotation with the inner rotor (2) by means of the external/internal toothing (33, 34) and, in the case of rotary drive, forms conveying cells (30, 31) in which the fluid is conveyed from the low-pressure chamber (17) to the high-pressure chamber (18),

   • an adjusting member (5) which causes an axial movement of the inner rotor (2) being provided,

   • the adjusting member (5) being guided axially movably in the internal toothing (34) of the outer rotor (3),

   • the outer rotor (3) having, in its tooth spaces of the internal toothing (34), radial ducts (41) arranged in the region of the low-pressure chamber (17) and of the high-pressure chamber (18),

   • the axial position of the inner rotor (2) in relation to the outer rotor (3) being variable by means of the axial movement of the adjusting member (5), and therefore the volume of the conveying cells (30, 31) being variable,
   characterized in that

   • the external toothing (33) of the inner rotor (2) has a form such that axially active springs (8) can be installed between the shaft (1) driving the inner rotor (2) and the tooth contour of the external toothing (33).
2. Internal gear pump according to Claim 1, characterized in that

   • in the inner rotor (2), the springs (8), which act axially on the adjusting member (5), are arranged between the shaft (1) driving the inner rotor (2) and the tooth contour of the external toothing (33), and

   • an adjusting space (25) connected to the high-pressure chamber (18) and delimited axially by the adjusting member (5) is formed within the internal toothing (34) of the outer rotor (3), pressure within the adjusting space (25) acting axially on the adjusting member (5) counter to the spring force of the springs (8), with conveying cells (30, 31) lying between them, in such a way that, with a rising pressure in the high-pressure chamber (18) and in the adjusting space (25), the adjusting member (5) is displaced counter to the spring force of the springs (8) and the volume of the conveying cells (30, 31) decreases.
3. Internal gear pump according to Claim 1 or 2, characterized in that the springs (8) are supported in the axial direction on the shaft (1) via a pot-shaped intermediate member (6) and a securing ring (12).
4. Internal gear pump according to one of Claims 1 to 3, characterized in that the adjusting member (5) has an external toothing (34a) which corresponds with an exact fit to a sufficient, but small running clearance of the internal toothing (34) of the outer rotor (3) and which is therefore axially movable sealingly therein.
5. Internal gear pump according to one of Claims 1 to 4, characterized in that the geometric form of the external/internal toothing (33, 34) is designed as an epicycloidal or circular-arc external toothing (33) which is located on the inner rotor (2) and which by means of a generator rolling movement generates the internal toothing (34) of the outer rotor (3) with one tooth more.
6. Internal gear pump according to one of Claims 1 to 4, characterized in that the geometric form of the external/internal toothing (33, 34) is determined by epicycloids and hypocycloids.
7. Internal gear pump according to one of Claims 1 to 6, characterized in that the inner rotor (2) is arranged, on the shaft (1) driving it, axially movably, but so as to be secured in terms of rotation, particularly by means of a feather key (11), and essentially in an impact-free manner.
8. Internal gear pump according to one of Claims 1 to 7, characterized in that the conveying cells (30, 31) are closed in the axial direction and opposite to the adjusting member (5) by means of a pinion plate (4), the internal toothing (32) of which corresponds with an exact fit to a sufficient, but small running clearance of the external toothing (33) of the inner rotor (2), in such a way that the inner rotor (2) is axially movable within the internal toothing (32) of the pinion plate (4).
9. Internal gear pump according to Claim 8, characterized in that a blading (42) corresponding to a centrifugal pump (21) is arranged or formed on the pinion plate (4).
10. Internal gear pump according to Claim 9, characterized in that the blading (42) corresponding to a centrifugal pump is an axial blading.
11. Internal gear pump according to one of Claims 1 to 10, characterized in that, between the casing (7) and a driving wheel (9) arranged outside the casing (7) on the shaft (1), a compensating pressure region (22) is provided which is acted upon by the high pressure and which acts to compensate the axial forces.
12. Internal gear pump according to Claim 3, characterized in that, between the casing (10) and the pot-shaped intermediate member (6a), a compensating pressure region (22a) is provided which is acted upon by the high pressure and which acts to compensate the axial forces.
13. Internal gear pump according to one of Claims 1 to 12, characterized in that the external toothing (33) of the inner rotor (2) has between 5 and 8 teeth.
14. Internal gear pump according to one of Claims 1 to 13, characterized in that the external toothing (33) of the inner rotor (2) has 6 teeth.
15. Internal gear pump according to Claim 14, characterized in that 3 springs (8) are arranged, distributed uniformly on the circumference, in the inner rotor (2).
16. Internal gear pump according to one of Claims 1 to 15, characterized in that the springs are designed as helical springs (8).

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