EP1406015B1 - Internal gear pump with improved filling - Google Patents

Internal gear pump with improved filling Download PDF

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Publication number
EP1406015B1
EP1406015B1 EP03020503A EP03020503A EP1406015B1 EP 1406015 B1 EP1406015 B1 EP 1406015B1 EP 03020503 A EP03020503 A EP 03020503A EP 03020503 A EP03020503 A EP 03020503A EP 1406015 B1 EP1406015 B1 EP 1406015B1
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EP
European Patent Office
Prior art keywords
toothed wheel
recesses
external toothing
tooth
front face
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP03020503A
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German (de)
French (fr)
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EP1406015A1 (en
Inventor
Sven Peters
Claus Welte
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Schwaebische Huettenwerke Automotive GmbH
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Schwaebische Huettenwerke Automotive GmbH
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/082—Details specially related to intermeshing engagement type machines or pumps
    • F04C2/088—Elements in the toothed wheels or the carter for relieving the pressure of fluid imprisoned in the zones of engagement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
    • F04C2/00—Rotary-piston machines or pumps
    • F04C2/08—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
    • F04C2/10—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member
    • F04C2/102—Rotary-piston machines or pumps of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of internal-axis type with the outer member having more teeth or tooth-equivalents, e.g. rollers, than the inner member the two members rotating simultaneously around their respective axes

Definitions

  • the invention relates to internal gear pumps, in particular internal gear pumps for use as lubricating oil pumps for internal combustion piston engines.
  • the DE 1263973 B deals with a rotary piston machine with eccentrically arranged gear-like rotary pistons, of which the outer directly entrains the inner, wherein the teeth of the inner rotary piston constantly touches the inner teeth of the outer rotary piston, or almost touched.
  • a liquid or gaseous working fluid is axially fed and discharged at an end face of the rotary piston.
  • the tooth gaps located between the tooth tips of the inner rotary piston are laterally bevelled and thus increase the volume of the delivery cells formed by the pistons. The purpose of this increase in volume is a reduction in the inflow and outflow velocity of the conveying or working medium to the feed cells.
  • the DE 4 200 883 is considered the closest prior art and discloses an internal gear pump having an internal gear having an axial groove in each root of the gear.
  • an inlet opening is provided, which is so wide in the radial direction that it covers the axial grooves on one end face.
  • the axial grooves in the bottom of the pinion tooth gaps ensure a certain dead space in which cavitation bubbles and squeeze oil filled with vapor of the operating fluid can collect.
  • the grooves can accordingly have in axial section circular arc profile or through the entire tooth width with constant profile.
  • the outlet opening on the pruch side of the pump is so wide in the radial direction that it covers the axial grooves on one end face.
  • the invention relates to an internal gear pump comprising a housing, at least one gear chamber formed in the housing and at least two in the gear chamber has received, meshed gears.
  • One of the gears is an externally toothed, internal gear, the other is an internally toothed, external gear.
  • the gears are rotatable about mutually offset axes of rotation.
  • In the gear chamber open at a low pressure side, which is also referred to as the suction side, at least one inlet opening and at a high pressure side at least one outlet opening for a pumpable from the pump fluid.
  • the fluid is preferably a hydraulic fluid.
  • the internal toothing of the outer gear has at least one tooth more than the outer toothing of the inner gear, preferably it has exactly one more tooth.
  • the gears form delivery cells that expand in the direction of rotation of the gears from a region of deepest meshing engagement to a region of least meshing on the low pressure side of the gear chamber, that is to increase, and then from the region of least meshing to the area of deepest meshing on the high pressure side reduce the gear chamber again, that is they form on the high pressure side compressing feed cells.
  • a rotary drive of the gears is sucked on the low pressure side of the gear chamber from the there expanding delivery cells fluid, promoted over the area of least gear mesh and displaced by the compressive feed cells on the high pressure side through the at least one outlet.
  • At least one depression is formed in the root of the tooth, preferably exactly at the apex, which according to the invention extends from an end face of the external toothing only into the base of the tooth, that is to say the indentations according to the invention are directed towards the relevant end face of the external toothing open and end each in the root of the tooth.
  • the recess formed according to the invention therefore does not extend continuously from one end face to the opposite other end face of the external toothing, but remains in the tooth roots a web which extends to the root circle of the external toothing and determines the root circle.
  • the depressions extend continuously axially from one end face to the other end face, they however have a greater radial depth on at least one of the end faces than in a region within the respective tooth root, ie in the case axially continuous depressions whose radial depth is not uniform over the entire axial length of the depression in question, but it is these recesses in the interior of the respective Zahnfußgrunds flatter than at least one of the two end faces of the outer teeth.
  • the radial depth of the depressions can in particular also increase from a shallowest point in the interior of the respective tooth root to both end faces of the external toothing.
  • the intake cross-section of the relevant delivery cell is enlarged on the low-pressure side of the gear chamber at the end face to which the depression extends.
  • the extent of the increase in the volume of the feed cell can be reduced compared to a uniformly deep axially extending recess with the same inlet cross-section at the end face.
  • This empty space is reduced due to the inventive design of the wells, because the feed cells compared to simple feed cells have an enlarged Ansaugquerites on the front side and compared to feed cells with continuously extending wells a smaller cell volume.
  • the degree of filling of the delivery cells can be increased by the optimal utilization of the centrifugal force for the purpose of fluid intake. The beginning of cavitation is thus shifted to higher speeds. Furthermore, the volumetric efficiency in the speed range above the beginning of cavitation decreases less than with conventional internal gear pumps.
  • each of the depressions is measured in the radial direction to the Zahnfußkontur without depression, ie exactly at the apex, it is measured on the root circle of the external teeth.
  • the depth can change in a single step.
  • the depth preferably varies continuously in the axial direction from a maximum depth on the front side to a minimum value, preferably down to the value "0". This will increase the volume of the Deepening and the relevant conveyor cell compared to a single-stage waste reduced.
  • the size of a space at high speeds with fluid not filled space within the delivery cell is accordingly also reduced in an advantageous manner.
  • the volume increase due to the depression compared to a single-stage waste can also be reduced by increasing the depth in several stages. It is particularly preferable if the depth in the axial direction decreases in a degressive manner from a maximum value on the end face of the external toothing to a lowest value in the interior of the tooth root.
  • the width of the recess measured in the circumferential direction of the external toothing decreases from a maximum value on the end side in the axial direction to the interior of the foot base, whereby this decrease is preferably continuous runs.
  • the recess in the root of the tooth is cone-shaped except with a rounded rounded in the interior of réelle grounds on the provoca Vietnamese end.
  • the recess can be formed by a subsequent machining of the inner gear, for example by milling. However, in particular, it can be formed directly in the initial formation of the gear, preferably in a press forming of a gear formed as a sintered part.
  • Recesses of the type according to the invention can be formed particularly advantageously on both end faces of the inner gear, wherein preferably a web remains between the two axially extending recesses of each Zahnfußgrounds, which extends to the root circle of the external toothing, that touches the root circle.
  • the in this case two depressions within a Zahnfußgrounds are preferably in the apex of the Zahnfußgrounds in an axial alignment. Further, they are in a preferred embodiment to the axial center of the inner gear mirror symmetry. If at both end faces ever one or a continuous recess opens, so preferably each of the two end faces opposite at least one inlet opening is formed, which covers the mouths of the recesses in the radial direction.
  • Recesses of the type according to the invention on both end sides of the external toothing are particularly advantageous if at least one respective inlet opening opens into the gear chamber at both end faces of the toothed wheel set.
  • Inlet ports on either side of the gear train are common in internal gear pumps, which are intended for high speed applications above 7000 rpm to ensure adequate charge pumping on the low pressure side, even at such high speeds.
  • the at least one outlet opening on the high-pressure side is narrower in the radial direction than the at least one inlet opening, specifically around the radial depth of the depressions opening in the opposite direction. If recesses open on both end sides of the external toothing and at least one outlet opening is formed on both end faces, these at least two outlet openings also cover delivery cells on the high-pressure side only up to the root base of the external toothing, but not the mouths of the recesses.
  • the invention further corresponds to when an outlet opening or in the direction of the gears behind one another a plurality of outlet openings is formed only on one end side in the case of opening to both end faces of the external teeth recesses or are.
  • Fig. 1 shows an internal gear pump with a housing 3, the housing cover is removed to release the view into a gear chamber 4.
  • the gear chamber 4 is a circular cylindrical chamber whose walls are formed by the housing 3 and the removed housing cover.
  • the walls form a circular cylindrical inner circumferential surface and two end faces, which are axially facing each other.
  • the view is in Fig. 1 directed against the back of these two faces. This rear end face and the circular cylindrical inner circumferential surface are formed by the housing and the other of the end walls is formed by the detached housing cover.
  • the gear chamber 4 accommodates a gear set consisting of two spur gears, namely an inner gear 1 and an outer gear 2.
  • the inner gear 1 is seated against rotation on a drive shaft 8 and is rotatable about the axis of rotation D 1 together with the drive shaft 8.
  • the outer gear 2 is on the circular cylindrical Inner circumferential surface of the gear chamber 4 rotatably mounted about a rotational axis D 2 by means of a sliding bearing.
  • the two axes of rotation D 1 and D 2 are mutually eccentric, ie offset in parallel, with the eccentricity "e".
  • the inner gear 1 is provided with an outer toothing 1a and the outer gear 2 is provided with an inner toothing 2i.
  • the two teeth 1a and 2i are in a meshing tooth engagement.
  • the external toothing 1a has one tooth less than the internal toothing 2i.
  • the two teeth 1a and 2i form in the tooth engagement between them delivery cells 7, which lead a pumped by the pump fluid.
  • inlet opening 5 and an outlet opening 6 for the fluid.
  • a further inlet opening and a further outlet opening which are shaped like the inlet opening 5 and the outlet opening 6, open on the front end face formed by the housing cover.
  • the inlet opening 5 is connected to a fluid inlet via a low-pressure channel formed in the housing 3, and the outlet opening 6 is connected to a fluid outlet of the housing 3 via a high-pressure channel formed in the housing 3.
  • the inlet opening formed in the housing cover is likewise connected to the low-pressure channel and the outlet opening formed in the housing cover is likewise connected to the high-pressure channel.
  • Each of the conveyor cell 7 is closed at least substantially pressure-tight against its in and against the direction of rotation D adjacent conveyor cells 7.
  • the sealing of the high pressure side of the gear chamber 4 from the low pressure side takes place in the region of deepest tooth engagement by the mutually pressing drive tooth flanks and in the region of least tooth engagement by the opposing tooth heads of the teeth 1a and 2i.
  • the gears 1 and 2 form at their end faces in each case sealing gaps with the axially facing opposite Kammerstirnwanditch the gear chamber 4, in which the inlet and the outlet openings are formed.
  • the two chamber end walls each form a sealing ridge.
  • the respective sealing web extends in the direction of rotation D both in the region of deepest tooth engagement and in the region of least tooth engagement between the ends of the inlet opening and the outlet opening facing there, and separates on the basis of its Sealing the respective openings and thus ultimately the low pressure side of the high pressure side.
  • the inner gear 1 is rotationally driven by the drive shaft 8 forth, for example in the drawn direction of rotation D, and takes the outer gear 2 in the same direction D due to the meshing tooth engagement.
  • the delivery cells 7 increase from a region of deepest meshing engagement, in the direction of rotation D, to a region of least meshing engagement, and decrease again from the region of lowest meshing engagement to the region of deepest meshing engagement. Due to the increasing delivery cells 7 is in the gear chamber 4, a low pressure side and by the decreasing delivery cells 7, a high pressure side is formed in the gear chamber 4.
  • the two gearwheels 1 and 2 are rotationally driven, fluid is sucked in through the inlet opening 5 and the inlet opening formed in the housing cover on the low-pressure side due to the delivery cells 7 expanding there and transported in the conveyor cells 7 over the region of least meshing with the high-pressure side.
  • the delivery cells 7 shrink, so that the fluid is displaced by increasing the pressure through the outlet opening 6 and the outlet opening formed in the housing cover, and through the high-pressure channel adjoining these two outlet openings to the housing outlet and finally to one with the fluid to be supplied unit flows.
  • the inner gear 1 of the internal gear pump is in Fig. 2 in a perspective view and in Fig. 3 in the view of Fig. 1 shown individually.
  • two recesses 10 are formed, which extend from an axially central web 11, starting in the axial direction to one of the two end faces of the inner gear 1.
  • Each of the recesses 10 opens at only one of the two end faces of the gear 1.
  • the remaining between the recesses 10 in the bottom of each of the toothed web 11 can be formed as Zahnfußprofil in a known manner, for example as Hypozykloide.
  • Each of the webs 11 touches the root circle F of the external toothing 1a, ie the webs 11 determine the root circle F. Is marked in FIG. 3 Further, the pitch circle W, which divides the profile of the external teeth 1a in tooth tips and tooth roots.
  • the depressions 10 have a round profile in cross-section with a width B measured in the circumferential direction.
  • the depressions 10 each have their greatest width B at their discharge point on the end face of the inner gearwheel 1.
  • This largest width B is shown as an example for one of the depressions 10.
  • the depth T in the apex of the tooth root is also shown by way of example for one of the depressions 10.
  • the depth T is measured in the radial direction and is related to the toothed profile of the webs 11 that has been extended in the axial direction over the depression 10. Also their greatest depth T, the recesses 10 on the end face of the inner gear 1, where they open. From the point of discharge at the end face to the web 11, the depth T decreases continuously in the axial direction.
  • Fig. 4 shows a portion of the inner gear, in which a recess 10 is formed, in a section.
  • the cutting plane is the axial / radial plane which divides the recess 10 into two equal halves.
  • the depression 10 has its respectively greatest depth T in the cross-sectional plane perpendicular to the axial / radial cutting plane.
  • the recess 10 flattens from the end face of the inner gear 1 to the web 11 continuously at an inclination angle ⁇ .
  • the flattening course of the recess 10 is further degressive to a small extent, that is, the inclination angle ⁇ , measured on the axial extension of the Zahnfußprofils the web 11, from the front side to the web 11 is also gradually from.
  • the depression 10 runs obliquely into the web 11, that is to say the angle of inclination ⁇ is unequal to "0" in the transition region between the depression 10 and the web 11.
  • the recesses 10 are each formed by a smooth lateral surface in the base of each of the tooth roots.
  • the recesses 10 are each conical with a round in a radial plan view transition region in the formed by the respective web 11 Zahnfußprofil.
  • the generatrix of the cone formed by each of the recesses 10 is slightly curved because of the changing inclination angle ⁇ . The shape could therefore also be called hyperboloid. A straight cone shape would also be possible.
  • the axially outwardly radially concave shape of the However, depressions 10 results per well 10 an advantageously large ratio of mouth cross-sectional area to volume.
  • the depressions 10 are formed exactly at the apex of the tooth feet, with the root circle F cutting in the apex axial / radial plane as the plane of symmetry.
  • the mouths of the recesses 10 are formed and arranged on the end face of the inner gear 10 in this way. From these mouths, however, the depressions 10 may well also run straight obliquely or arcuately to the axial to the respective web 11 in order to influence the Einströmmik in the relevant conveyor cell 7.
  • the inlet opening 5 and the outlet opening 6 are recessed in the posterior Kammerstirnwandung as kidney-shaped openings. They extend in the circumferential direction depending on several conveyor cells 7, wherein they cover the respective conveyor cells 7 radially.
  • the inlet opening 5 also radially overlaps the depressions 10.
  • the outlet opening 6 extends radially only up to the root circle of the external toothing 1a, so that no fluid is displaced directly from the depressions 10.
  • the comments made regarding the inlet opening 5 and the outlet opening 6 also apply to the inlet opening and the optionally existing outlet opening in the removed housing cover. In the housing cover, but no outlet opening must be formed. During the rotational movement of the toothed wheels 1 and 2, therefore, the recesses 10 sweep the inlet opening 5 and the axially opposite inlet opening in the housing cover.
  • FIGS. 5 and 6 the volumetric efficiency E is plotted against the speed R of the driven gear 1.
  • Fig. 5 shows the curve of the volumetric efficiency E for an internal gear pump with a gear set without recesses
  • Fig. 6 shows for comparison the volumetric efficiency E for an internal gear pump according to the invention.
  • the internal gear pump forms the lubricating oil pump for a Verbrennungshubkolbenmotor a car or truck. This is a particularly preferred example of use for an internal gear pump according to the invention.
  • the installation situation of the pump is in this case such that the driven gear, in the example, the inner gear 1, with a speed R of up to 14,000 revolutions per minute (RPM) is driven, that is, it is from a crankshaft of the engine with a relation to the crankshaft translated speed driven. From a drive speed of about 7,000 rpm, the conventional pump uses cavitation. An arrow K indicates the beginning of cavitation. As the speed increases, the volumetric efficiency E decreases.
  • RPM revolutions per minute
  • the volumetric efficiency E of an internal gear pump identical in construction to those of the recesses 10 according to the invention is shown in FIG Fig. 6 applied in comparison.
  • the beginning of cavitation K can be shifted to significantly higher speeds.
  • the start of cavitation K could be shifted to a speed higher by about 2,000 rpm.
  • the volumetric efficiency E in the upwardly adjoining speed range decreases less sharply than in the case of the conventional internal gear pump without recesses.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Rotary Pumps (AREA)

Abstract

The pump has a housing (3) containing a gear chamber (4), which itself contains an internal gear wheel (1) and an external gear wheel (2). There is at least one recess (10) in the feet of the external teeth (1a), extending to one endface of these teeth. This endface has a greater radial depth than the inner region of the tooth foot base spaced out axially from the endface.

Description

Die Erfindung betrifft Innenzahnradpumpen, insbesondere Innenzahnradpumpen für die Verwendung als Schmierölpumpen für Verbrennungskolbenmotoren.The invention relates to internal gear pumps, in particular internal gear pumps for use as lubricating oil pumps for internal combustion piston engines.

Bei üblichen Innenzahnradpumpen entstehen bei Drehzahlen des Zahnradsatzes der Pumpen oberhalb von 7000 U/min so hohe Strömungsgeschwindigkeiten, dass eine vollständige Befüllung des Zahnradsatzes nicht mehr möglich ist. Durch die unvollständige Befüllung entsteht Kavitation. Mit dem Beginn der Kavitation knickt der volumetrische Wirkungsgrad der Pumpe deutlich ab, das heißt der volumetrische Wirkungsgrad verschlechtert sich.In conventional internal gear pumps arise at speeds of the gear set of pumps above 7000 U / min so high flow velocities that a complete filling of the gear set is no longer possible. The incomplete filling causes cavitation. With the onset of cavitation, the volumetric efficiency of the pump drops significantly, that is, the volumetric efficiency deteriorates.

Die DE 1263973 B behandelt eine Drehkolbenmaschine mit exzentrisch ineinander angeordneten zahnradartigen Drehkolben, von denen der äußere den inneren unmittelbar mitnimmt, wobei die Verzahnung des inneren Drehkolbens ständig die Innenverzahnung des äußeren Drehkolbens berührt, bzw. fast berührt. In die so gebildeten Förderzellen wird ein flüssiges bzw. gasförmiges Arbeitsmedium an einer Stirnseite des Drehkolbens axial zu- und abgeleitet. Die zwischen den Zahnköpfen des inneren Drehkolbens befindlichen Zahnlücken sind seitlich abgeschrägt und vergrößern somit das Volumen der durch die Kolben gebildeten Förderzellen. Zweck dieser Volumensvergrößerung ist eine Verringerung der Ein- und Ausströmgeschwindigkeit des Förder- oder Arbeitsmediums zu den Förderzellen.The DE 1263973 B deals with a rotary piston machine with eccentrically arranged gear-like rotary pistons, of which the outer directly entrains the inner, wherein the teeth of the inner rotary piston constantly touches the inner teeth of the outer rotary piston, or almost touched. In the conveyor cells thus formed, a liquid or gaseous working fluid is axially fed and discharged at an end face of the rotary piston. The tooth gaps located between the tooth tips of the inner rotary piston are laterally bevelled and thus increase the volume of the delivery cells formed by the pistons. The purpose of this increase in volume is a reduction in the inflow and outflow velocity of the conveying or working medium to the feed cells.

Die DE 4 200 883 wird als nächstligegender Stand der Technik angesehen und offenbart eine Innenzahnradpumpe mit einem inneren Zahnrad, das in jedem Zahnfußgrund eine Axialnut aufweist. Auf der Saugseite der Pumpe ist eine Einlassöffnung vorgesehen, die in radialer Richtung so breit ist, dass sie die Axialnuten an einer Stirnseite überdeckt. Die Axialnuten im Grund der Ritzelzahnlücken gewährleisten einen gewissen Totraum, in dem sich mit Dampf der Betriebsflüssigkeit gefüllte Kavitationsblasen und Quetschöl sammeln können. Die Nuten können dementsprechend im Axialschnitt Kreisbogenprofil haben oder über die ganze Zahnbreite mit konstantem Profil durchlaufen. Auch die Auslassöffnung auf der Pruchseite der Pumpe ist in radialer Richtung so breit, dass sie die Axialnuten an einer Stirnseite überdeckt.The DE 4 200 883 is considered the closest prior art and discloses an internal gear pump having an internal gear having an axial groove in each root of the gear. On the suction side of the pump, an inlet opening is provided, which is so wide in the radial direction that it covers the axial grooves on one end face. The axial grooves in the bottom of the pinion tooth gaps ensure a certain dead space in which cavitation bubbles and squeeze oil filled with vapor of the operating fluid can collect. The grooves can accordingly have in axial section circular arc profile or through the entire tooth width with constant profile. The outlet opening on the pruch side of the pump is so wide in the radial direction that it covers the axial grooves on one end face.

Es ist eine Aufgabe der Erfindung, den volumetrischen Wirkungsgrad von Innenzahnradpumpen zu verbessern.It is an object of the invention to improve the volumetric efficiency of internal gear pumps.

Die Erfindung betrifft eine Innenzahnradpumpe, die ein Gehäuse, wenigstens eine in dem Gehäuse gebildete Zahnradkammer und wenigstens zwei in der Zahnradkammer aufgenommene, in Zahneingriff befindlichen Zahnräder aufweist. Das eine der Zahnräder ist ein außenverzahntes, inneres Zahnrad, das andere ist ein innenverzahntes, äußeres Zahnrad. Die Zahnräder sind um zueinander versetzte Drehachsen drehbar. In die Zahnradkammer münden an einer Niederdruckseite, die auch als Saugseite bezeichnet wird, wenigstens eine Einlassöffnung und an einer Hochdruckseite wenigstens eine Auslassöffnung für ein von der Pumpe zu förderndes Fluid. Bei dem Fluid handelt es sich vorzugsweise um eine hydraulische Flüssigkeit.The invention relates to an internal gear pump comprising a housing, at least one gear chamber formed in the housing and at least two in the gear chamber has received, meshed gears. One of the gears is an externally toothed, internal gear, the other is an internally toothed, external gear. The gears are rotatable about mutually offset axes of rotation. In the gear chamber open at a low pressure side, which is also referred to as the suction side, at least one inlet opening and at a high pressure side at least one outlet opening for a pumpable from the pump fluid. The fluid is preferably a hydraulic fluid.

Die Innenverzahnung des äußeren Zahnrads weist wenigstens einen Zahn mehr auf als die Außenverzahnung des inneren Zahnrads, vorzugsweise weist sie genau einen Zahn mehr auf. Die Verzahnungen bilden Förderzellen, die in Drehrichtung der Zahnräder von einem Bereich tiefsten Zahneingriffs bis zu einem Bereich geringsten Zahneingriffs auf der Niederdruckseite der Zahnradkammer expandieren, das heißt sich vergrößern, und sich anschließend von dem Bereich geringsten Zahneingriffs bis zu dem Bereich tiefsten Zahneingriffs auf der Hochdruckseite der Zahnradkammer wieder verkleinern, das heißt sie bilden auf der Hochdruckseite komprimierende Förderzellen. Bei einem Drehantrieb der Zahnräder wird auf der Niederdruckseite der Zahnradkammer von den dort expandierenden Förderzellen Fluid angesaugt, über den Bereich geringsten Zahneingriffs gefördert und von den komprimierenden Förderzellen auf der Hochdruckseite durch die wenigstens eine Auslassöffnung verdrängt.The internal toothing of the outer gear has at least one tooth more than the outer toothing of the inner gear, preferably it has exactly one more tooth. The gears form delivery cells that expand in the direction of rotation of the gears from a region of deepest meshing engagement to a region of least meshing on the low pressure side of the gear chamber, that is to increase, and then from the region of least meshing to the area of deepest meshing on the high pressure side reduce the gear chamber again, that is they form on the high pressure side compressing feed cells. In a rotary drive of the gears is sucked on the low pressure side of the gear chamber from the there expanding delivery cells fluid, promoted over the area of least gear mesh and displaced by the compressive feed cells on the high pressure side through the at least one outlet.

In Zahnfüßen der Außenverzahnung ist in dem Zahnfußgrund, vorzugsweise exakt im Scheitel, je wenigstens eine Vertiefung gebildet, die sich nach der Erfindung von einer Stirnseite der Außenverzahnung nur bis in den Zahnfußgrund erstreckt, das heißt die erfindungsgemäßen Vertiefungen sind zu der betreffenden Stirnseite der Außenverzahnung hin offen und enden je in dem Zahnfußgrund. Die erfindungsgemäß gebildete Vertiefung erstreckt sich somit nicht von einer Stirnseite zu der gegenüber liegenden anderen Stirnseite der Außenverzahnung durchgehend, sondern es verbleibt in den Zahnfüßen ein Steg, der an den Fußkreis der Außenverzahnung heran reicht und den Fußkreis bestimmt. Sollten die Vertiefungen sich in der einen oder anderen Ausführungsform der Erfindung axial von einer Stirnseite bis zu der anderen Stirnseite durchgehend erstrecken, so weisen sie jedoch an zumindest einer der Stirnseiten eine größere radiale Tiefe als in einem Bereich innerhalb des jeweiligen Zahnfugrunds auf, d.h. im Falle axial durchgehender Vertiefungen ist deren radiale Tiefe nicht über die gesamte axiale Länge der betreffenden Vertiefung gleichmäßig, sondern es sind diese Vertiefungen im Inneren des jeweiligen Zahnfußgrunds flacher als an wenigstens einer der zwei Stirnseiten der Außenverzahnung. Die radiale Tiefe der Vertiefungen kann insbesondere auch von einer flachsten Stelle im Inneren des jeweiligen Zahnfußgrunds zu beiden Stirnseiten der Außenverzahnung hin zunehmen. Die Aussage über den Tiefenunterschied gilt auch für die zuerst genannten Ausführungsformen, in denen die Vertiefungen im Zahnfußgrund unter Verbleib eines Stegs enden. Ebenso gilt die Aussage für Vertiefungen, deren radiale Tiefe sich nur einmal, nämlich an solch einem Steg oder an einer inneren Flachstelle, ändert.In tooth roots of the external toothing, at least one depression is formed in the root of the tooth, preferably exactly at the apex, which according to the invention extends from an end face of the external toothing only into the base of the tooth, that is to say the indentations according to the invention are directed towards the relevant end face of the external toothing open and end each in the root of the tooth. The recess formed according to the invention therefore does not extend continuously from one end face to the opposite other end face of the external toothing, but remains in the tooth roots a web which extends to the root circle of the external toothing and determines the root circle. If, in one or another embodiment of the invention, the depressions extend continuously axially from one end face to the other end face, they however have a greater radial depth on at least one of the end faces than in a region within the respective tooth root, ie in the case axially continuous depressions whose radial depth is not uniform over the entire axial length of the depression in question, but it is these recesses in the interior of the respective Zahnfußgrunds flatter than at least one of the two end faces of the outer teeth. The radial depth of the depressions can in particular also increase from a shallowest point in the interior of the respective tooth root to both end faces of the external toothing. The statement about the difference in depth also applies to the first-mentioned embodiments, in which the depressions in the root of the tooth end in the fate of a web. Likewise, the statement applies to depressions whose radial depth changes only once, namely at such a web or at an inner flat location.

Durch die erfindungsgemäß gebildete Vertiefung wird auf der Niederdruckseite der Zahnradkammer an der Stirnseite, zu der die Vertiefung sich erstreckt, der Ansaugquerschnitt der betreffenden Förderzelle vergrößert. Andererseits kann das Ausmaß der Vergrößerung des Volumens der Förderzelle im Vergleich zu einer axial durchgehend mit gleichmäßiger Tiefe sich erstreckenden Vertiefung bei gleichem Einlassquerschnitt an der Stirnseite verringert werden. Mit zunehmender Drehzahl der Zahnräder werden die nach radial auswärts gerichteten, auf das Fluid wirkenden Fliehkräfte innerhalb der Förderzellen größer, was zusätzlich zu der Expansion der Förderzellen auf der Niederdruckseite einen nach radial auswärts gerichteten Sog bewirkt. Auf Grund der Fliehkraft wird das Fluid an das äußere Zahnrad gepresst, während am inneren Zahnrad ohne die Vertiefungen ein leerer Raum verbliebe. Dieser leere Raum wird auf Grund der erfindungsgemäßen Ausbildung der Vertiefungen verringert, weil die Förderzellen im Vergleich zu einfachen Förderzellen einen vergrößerten Ansaugquerschnitt an der Stirnseite und im Vergleich zu Förderzellen mit durchgehend erstreckten Vertiefungen ein geringeres Zellenvolumen aufweisen. Der Füllgrad der Förderzellen kann durch die optimale Ausnutzung der Fliehkraft zum Zwecke der Fluidansaugung gesteigert werden. Der Kavitationsbeginn wird somit zu höheren Drehzahlen verschoben. Des Weiteren sinkt der volumetrische Wirkungsgrad im Drehzahlbereich oberhalb des Kavitationsbeginns weniger stark ab als bei herkömmlichen Innenzahnradpumpen.By means of the depression formed according to the invention, the intake cross-section of the relevant delivery cell is enlarged on the low-pressure side of the gear chamber at the end face to which the depression extends. On the other hand, the extent of the increase in the volume of the feed cell can be reduced compared to a uniformly deep axially extending recess with the same inlet cross-section at the end face. As the speed of the gears increases, the radially outward centrifugal forces acting on the fluid within the delivery cells become larger, which in addition to the expansion of the delivery cells on the low pressure side, causes a radially outward suction. Due to the centrifugal force, the fluid is pressed against the outer gear, while the inner gear without the wells left an empty space. This empty space is reduced due to the inventive design of the wells, because the feed cells compared to simple feed cells have an enlarged Ansaugquerschnitt on the front side and compared to feed cells with continuously extending wells a smaller cell volume. The degree of filling of the delivery cells can be increased by the optimal utilization of the centrifugal force for the purpose of fluid intake. The beginning of cavitation is thus shifted to higher speeds. Furthermore, the volumetric efficiency in the speed range above the beginning of cavitation decreases less than with conventional internal gear pumps.

Die Tiefe jeder der Vertiefungen wird in radialer Richtung auf die Zahnfußkontur ohne Vertiefung gemessen, d.h. exakt im Scheitel wird sie auf den Fußkreis der Außenverzahnung gemessen. Die Tiefe kann sich in einer einzigen Stufe ändern. Bevorzugt ändert sich die Tiefe jedoch in axialer Richtung kontinuierlich von einer größten Tiefe an der Stirnseite bis auf einen Minimalwert, vorzugsweise bis auf den Wert "0". Hierdurch wird das Volumen der Vertiefung und der betreffenden Förderzelle gegenüber einem einstufigen Abfall verringert. Die Größe eines bei hohen Drehzahlen mit Fluid nicht gefüllten Raums innerhalb der Förderzelle wird dementsprechend in vorteilhafter Weise ebenfalls verringert. Grundsätzlich kann die auf die Vertiefung zurückzuführende Volumenvergrößerung gegenüber einem einstufigen Abfall auch durch die Zunahme der Tiefe in mehreren Stufen reduziert werden. Besonders bevorzugt ist es, wenn die Tiefe in axialer Richtung von einem größten Wert an der Stirnseite der Außenverzahnung bis zu einem geringsten Wert im Inneren des Zahnfußgrunds degressiv abnimmt.The depth of each of the depressions is measured in the radial direction to the Zahnfußkontur without depression, ie exactly at the apex, it is measured on the root circle of the external teeth. The depth can change in a single step. However, the depth preferably varies continuously in the axial direction from a maximum depth on the front side to a minimum value, preferably down to the value "0". This will increase the volume of the Deepening and the relevant conveyor cell compared to a single-stage waste reduced. The size of a space at high speeds with fluid not filled space within the delivery cell is accordingly also reduced in an advantageous manner. In principle, the volume increase due to the depression compared to a single-stage waste can also be reduced by increasing the depth in several stages. It is particularly preferable if the depth in the axial direction decreases in a degressive manner from a maximum value on the end face of the external toothing to a lowest value in the interior of the tooth root.

Um das Verhältnis aus Ansaugquerschnitt zu Förderzellenvolumen weiter zu vergrößern und dadurch zu optimieren, nimmt auch die in Umfangsrichtung der Außenverzahnung gemessene Breite der Vertiefung von einem größten Wert an der Stirnseite in axialer Richtung bis in das Innere des Fußgrunds ab, wobei auch diese Abnahme vorzugsweise kontinuierlich verläuft. Einfach herstellbar und nicht zuletzt deshalb bevorzugt, ist die Vertiefung im Zahnfußgrund kegelförmig ausgenommen mit einem im Inneren des Fußgrunds an dem Fußkreis gerundet auslaufenden Ende.In order to further increase the ratio of intake cross-section to delivery cell volume and thereby optimize, the width of the recess measured in the circumferential direction of the external toothing decreases from a maximum value on the end side in the axial direction to the interior of the foot base, whereby this decrease is preferably continuous runs. Easy to produce and not least therefore preferred, the recess in the root of the tooth is cone-shaped except with a rounded rounded in the interior of Fußgrunds on the Fußkreis end.

Die Vertiefung kann durch eine nachträgliche Bearbeitung des inneren Zahnrads geformt werden, beispielsweise durch Einfräsen. Sie kann insbesondere jedoch unmittelbar bei der Urformung des Zahnrads, vorzugsweise bei einem Pressformen eines als Sinterteil gebildeten Zahnrads geformt werden.The recess can be formed by a subsequent machining of the inner gear, for example by milling. However, in particular, it can be formed directly in the initial formation of the gear, preferably in a press forming of a gear formed as a sintered part.

So weit in den vorstehenden Ausführungen vorteilhafte Merkmale nur in Bezug auf eine Vertiefung beschrieben werden, sollen diese Ausführungen auch für die weiteren erfindungsgemäß gebildeten Vertiefungen des inneren Zahnrads gelten, die vorzugsweise jeweils gleich ausgebildet sind.As far as in the above embodiments advantageous features are described only in relation to a recess, these statements are also valid for the further inventively formed recesses of the inner gear, which are preferably each formed the same.

Vertiefungen der erfindungsgemäßen Art können besonders vorteilhaft an beiden Stirnseiten des inneren Zahnrads gebildet sein, wobei zwischen den beiden axial erstreckten Vertiefungen eines jeden Zahnfußgrunds vorzugsweise ein Steg verbleibt, der bis an den Fußkreis der Außenverzahnung reicht, das heißt den Fußkreis berührt. Die in diesem Fall zwei Vertiefungen innerhalb eines Zahnfußgrunds liegen vorzugsweise im Scheitel des Zahnfußgrunds in einer axialen Flucht. Ferner sind sie in bevorzugter Ausführung zu der axialen Mitte des inneren Zahnrades spiegelsymmetrisch. Falls an beiden Stirnseiten je eine oder eine durchgehende Vertiefung mündet, so ist vorzugsweise jeder der beiden Stirnseiten gegenüberliegend je wenigstens eine Einlassöffnung gebildet, die in radialer Richtung die Mündungen der Vertiefungen überdeckt.Recesses of the type according to the invention can be formed particularly advantageously on both end faces of the inner gear, wherein preferably a web remains between the two axially extending recesses of each Zahnfußgrunds, which extends to the root circle of the external toothing, that touches the root circle. The in this case two depressions within a Zahnfußgrunds are preferably in the apex of the Zahnfußgrunds in an axial alignment. Further, they are in a preferred embodiment to the axial center of the inner gear mirror symmetry. If at both end faces ever one or a continuous recess opens, so preferably each of the two end faces opposite at least one inlet opening is formed, which covers the mouths of the recesses in the radial direction.

Vertiefungen der erfindungsgemäßen Art an beiden Stirnseiten der Außenverzahnung sind insbesondere dann von Vorteil, wenn in die Zahnradkammer an beiden Stirnseiten des Zahnradlaufsatzes wenigstens je eine Einlassöffnung mündet. Einlassöffnungen beiderseits des Zahnradlaufsatzes sind bei Innenzahnradpumpen üblich, d1ie für Verwendungen im hohen Drehzahlbereich von über 7000 U/min vorgesehen sind, um auch bei solch hohen Drehzahlen eine ausreichende Befüllung der Förderzellen auf der Niederdruckseite zu gewährleisten.Recesses of the type according to the invention on both end sides of the external toothing are particularly advantageous if at least one respective inlet opening opens into the gear chamber at both end faces of the toothed wheel set. Inlet ports on either side of the gear train are common in internal gear pumps, which are intended for high speed applications above 7000 rpm to ensure adequate charge pumping on the low pressure side, even at such high speeds.

Die wenigstens eine Auslassöffnung an der Hochdruckseite ist in radialer Richtung schmaler als die wenigstens eine Einlassöffnung, und zwar um die radiale Tiefe der hier gegenüberliegend mündenden Vertiefungen. Falls Vertiefungen zu beiden Stirnseiten der Außenverzahnung münden und zu beiden Stirnseiten je wenigstens eine Auslassöffnung ausgebildet ist, decken auch diese wenigstens zwei Auslassöffnungen Förderzellen auf der Hochdruckseite nur jeweils bis zu dem Zahnfußgrund der Außenverzahnung ab, nicht jedoch die Mündungen der Vertiefungen. Der Erfindung entspricht es ferner, wenn im Falle von zu beiden Stirnseiten der Außenverzahnung mündenden Vertiefungen eine Auslassöffnung oder in Richtung der Zahnräder hintereinander mehrere Auslassöffnungen nur an einer Stirnseite gebildet ist oder sind. Die Ausbildung wenigstens einer Einlassöffnung, die auf der Niederdruckseite in radialer Richtung die Vertiefungen überdeckt, und gleichzeitig wenigstens einer Auslassöffnung, die auf der Hochdruckseite die Vertiefungen nicht überdeckt, sozusagen abdichtet, ist vorteilhaft nicht nur in Verbindung mit den erfindungsgemäß gebildeten Vertiefungen, sondern grundsätzlich auch mit axial durchgehenden Vertiefungen, die einen konstanten Querschnitt aufweisen, beispielsweise in Kombination mit axial geraden Nuten.The at least one outlet opening on the high-pressure side is narrower in the radial direction than the at least one inlet opening, specifically around the radial depth of the depressions opening in the opposite direction. If recesses open on both end sides of the external toothing and at least one outlet opening is formed on both end faces, these at least two outlet openings also cover delivery cells on the high-pressure side only up to the root base of the external toothing, but not the mouths of the recesses. The invention further corresponds to when an outlet opening or in the direction of the gears behind one another a plurality of outlet openings is formed only on one end side in the case of opening to both end faces of the external teeth recesses or are. The formation of at least one inlet opening which covers the recesses in the radial direction on the low-pressure side, and at the same time at least one outlet opening which does not cover the recesses on the high-pressure side, so to speak seals off advantageously not only in connection with the recesses formed according to the invention but also in principle with axially continuous recesses which have a constant cross-section, for example in combination with axially straight grooves.

Auch die Unteransprüche und deren Kombinationen beschreiben bevorzugte Merkmale, die auch die vorstehend beschriebenen Ausgestaltungen ergänzen können oder von diesen ergänzt werden können.The subclaims and their combinations also describe preferred features which can also supplement the embodiments described above or can be supplemented by them.

Die Erfindung wird nachfolgend anhand eines Ausführungsbeispiels erläutert. An dem Ausführungsbeispiel offenbar werdende Merkmale bilden je einzeln und in jeder Merkmalskombination die Gegenstände der Ansprüche und die vorstehend beschriebenen Ausgestaltungen vorteilhaft weiter. Es zeigen:

Fig. 1
eine Innenzahnradpumpe in einer Ansicht,
Fig. 2
ein inneres Zahnrad mit Vertiefungen, die sich je nur zu einer Stirnseite des Zahnrads erstrecken,
Fig. 3
das Zahnrad der Fig. 2 in einer Ansicht auf eine seiner Stirnseiten,
Fig. 4
das Zahnrad der Fig. 2 und 3 in einem axialen Teilschnitt im Bereich einer der Vertiefungen,
Fig. 5
den über der Drehzahl aufgetragenen volumetrischen Wirkungsgrad einer herkömmlichen Innenzahnradpumpe, und
Fig. 6
den über der Drehzahl aufgetragenen volumetrischen Wirkungsgrad einer erfindungsgemäßen Innenzahnradpumpe.
The invention will be explained below with reference to an embodiment. The features disclosed in the exemplary embodiment advantageously each individually and in each combination of features form the subject matter of the claims and the embodiments described above. Show it:
Fig. 1
an internal gear pump in a view
Fig. 2
an inner gear with recesses, which extend only to one end face of the gear,
Fig. 3
the gear of the Fig. 2 in a view on one of his front pages,
Fig. 4
the gear of the Fig. 2 and 3 in an axial partial section in the region of one of the depressions,
Fig. 5
the plotted over the speed volumetric efficiency of a conventional internal gear pump, and
Fig. 6
the applied over the speed volumetric efficiency of an internal gear pump according to the invention.

Fig. 1 zeigt eine Innenzahnradpumpe mit einem Gehäuse 3, dessen Gehäusedeckel abgenommen ist, um den Blick in eine Zahnradkammer 4 freizugeben. Die Zahnradkammer 4 ist eine kreiszylindrische Kammer, deren Wandungen von dem Gehäuse 3 und dem abgenommenen Gehäusedeckel gebildet werden. Die Wandungen bilden eine kreiszylindrische Innenmantelfläche und zwei Stirnflächen, die sich axial zugewandt gegenüber liegen. Der Blick ist in Fig. 1 gegen die rückwärtige dieser beiden Stirnflächen gerichtet. Diese rückwärtige Stirnfläche und die kreiszylindrische Innenmantelfläche werden von dem Gehäuse und die andere der Stirnwandungen wird von dem abgenommenen Gehäusedeckel gebildet. Fig. 1 shows an internal gear pump with a housing 3, the housing cover is removed to release the view into a gear chamber 4. The gear chamber 4 is a circular cylindrical chamber whose walls are formed by the housing 3 and the removed housing cover. The walls form a circular cylindrical inner circumferential surface and two end faces, which are axially facing each other. The view is in Fig. 1 directed against the back of these two faces. This rear end face and the circular cylindrical inner circumferential surface are formed by the housing and the other of the end walls is formed by the detached housing cover.

Die Zahnradkammer 4 nimmt einen Zahnradlaufsatz bestehend aus zwei Stirnzahnrädern auf, nämlich ein inneres Zahnrad 1 und ein äußeres Zahnrad 2. Das innere Zahnrad 1 sitzt verdrehgesichert auf einer Antriebswelle 8 und ist zusammen mit der Antriebswelle 8 um deren Drehachse D1 drehbar. Das äußere Zahnrad 2 ist an der kreiszylindrischen Innenmantelfläche der Zahnradkammer 4 um eine Drehachse D2 drehgelagert im Wege einer Gleitlagerung. Die beiden Drehachsen D1 und D2 verlaufen zueinander exzentrisch, d.h. parallel versetzt, mit der Exzentrizität "e".The gear chamber 4 accommodates a gear set consisting of two spur gears, namely an inner gear 1 and an outer gear 2. The inner gear 1 is seated against rotation on a drive shaft 8 and is rotatable about the axis of rotation D 1 together with the drive shaft 8. The outer gear 2 is on the circular cylindrical Inner circumferential surface of the gear chamber 4 rotatably mounted about a rotational axis D 2 by means of a sliding bearing. The two axes of rotation D 1 and D 2 are mutually eccentric, ie offset in parallel, with the eccentricity "e".

Das innere Zahnrad 1 ist mit einer Außenverzahnung 1a und das äußere Zahnrad 2 ist mit einer Innenverzahnung 2i versehen. Die beiden Verzahnungen 1a und 2i stehen in einem kämmenden Zahneingriff. Die Außenverzahnung 1a hat einen Zahn weniger als die Innenverzahnung 2i. Die beiden Verzahnungen 1a und 2i bilden in dem Zahneingriff zwischen sich Förderzellen 7, die ein von der Pumpe zu förderndes Fluid führen.The inner gear 1 is provided with an outer toothing 1a and the outer gear 2 is provided with an inner toothing 2i. The two teeth 1a and 2i are in a meshing tooth engagement. The external toothing 1a has one tooth less than the internal toothing 2i. The two teeth 1a and 2i form in the tooth engagement between them delivery cells 7, which lead a pumped by the pump fluid.

In die Zahnradkammer 4 münden an deren hinteren Stirnfläche eine Einlassöffnung 5 und eine Auslassöffnung 6 für das Fluid. Ebenso münden an der von dem Gehäusedeckel gebildeten vorderen Stirnfläche eine weitere Einlassöffnung und eine weitere Auslassöffnung, die so wie die Einlassöffnung 5 und die Auslassöffnung 6 geformt sind. Die Einlassöffnung 5 ist über einen in dem Gehäuse 3 gebildeten Niederdruckkanal mit einem Fluideinlass und die Auslassöffnung 6 ist über einen in dem Gehäuse 3 gebildeten Hochdruckkanal mit einem Fluidauslass des Gehäuses 3 verbunden. Die in dem Gehäusedeckel gebildete Einlassöffnung ist ebenfalls mit dem Niederdruckkanal und die in dem Gehäusedeckel gebildete Auslassöffnung ist ebenfalls mit dem Hochdruckkanal verbunden.In the gear chamber 4 open at the rear end face an inlet opening 5 and an outlet opening 6 for the fluid. Likewise, a further inlet opening and a further outlet opening, which are shaped like the inlet opening 5 and the outlet opening 6, open on the front end face formed by the housing cover. The inlet opening 5 is connected to a fluid inlet via a low-pressure channel formed in the housing 3, and the outlet opening 6 is connected to a fluid outlet of the housing 3 via a high-pressure channel formed in the housing 3. The inlet opening formed in the housing cover is likewise connected to the low-pressure channel and the outlet opening formed in the housing cover is likewise connected to the high-pressure channel.

Jede der Förderzelle 7 ist gegen ihre in und gegen die Drehrichtung D benachbarten Förderzellen 7 zumindest im Wesentlichen druckdicht abgeschlossen. Die Abdichtung der Hochdruckseite der Zahnradkammer 4 von der Niederdruckseite erfolgt in dem Bereich tiefsten Zahneingriffs durch die gegeneinander drückenden Antriebszahnflanken und in dem Bereich geringsten Zahneingriffs durch die einander gegenüber liegenden Zahnköpfe der Verzahnungen 1a und 2i. In axialer Richtung bilden die Zahnräder 1 und 2 an ihren Stirnseiten jeweils Dichtspalten mit den axial zugewandt gegenüber liegenden Kammerstirnwandungen der Zahnradkammer 4, in denen die Einlass- und die Auslassöffnungen gebildet sind. In dem Bereich tiefsten Zahneingriffs und in dem Bereich geringsten Zahneingriffs bilden die beiden Kammerstirnwandungen jeweils einen Dichtsteg. Der jeweilige Dichtsteg erstreckt sich in Drehrichtung D sowohl in dem Bereich tiefsten Zahneingriffs als auch in dem Bereich geringsten Zahneingriffs zwischen den dort einander zugewandten Enden der Einlassöffnung und der Auslassöffnung und trennt auf Grund seiner Dichtwirkung die jeweiligen Öffnungen und dadurch letztlich die Niederdruckseite von der Hochdruckseite.Each of the conveyor cell 7 is closed at least substantially pressure-tight against its in and against the direction of rotation D adjacent conveyor cells 7. The sealing of the high pressure side of the gear chamber 4 from the low pressure side takes place in the region of deepest tooth engagement by the mutually pressing drive tooth flanks and in the region of least tooth engagement by the opposing tooth heads of the teeth 1a and 2i. In the axial direction, the gears 1 and 2 form at their end faces in each case sealing gaps with the axially facing opposite Kammerstirnwandungen the gear chamber 4, in which the inlet and the outlet openings are formed. In the region of the deepest tooth engagement and in the region of least tooth engagement, the two chamber end walls each form a sealing ridge. The respective sealing web extends in the direction of rotation D both in the region of deepest tooth engagement and in the region of least tooth engagement between the ends of the inlet opening and the outlet opening facing there, and separates on the basis of its Sealing the respective openings and thus ultimately the low pressure side of the high pressure side.

Für eine Fluidförderung wird das innere Zahnrad 1 von der Antriebswelle 8 her drehangetrieben, beispielsweise in die eingezeichnete Drehrichtung D, und nimmt auf Grund des kämmenden Zahneingriffs das äußere Zahnrad 2 in die gleiche Drehrichtung D mit. Bei der Drehbewegung vergrößern sich die Förderzellen 7 von einem Bereich tiefsten Zahneingriffs ausgehend, in Drehrichtung D bis zu einem Bereich geringsten Zahneingriffs, und verkleinern sich wieder von dem Bereich geringsten Zahneingriffs bis zu dem Bereich tiefsten Zahneingriffs. Durch die sich vergrößernden Förderzellen 7 wird in der Zahnradkammer 4 eine Niederdruckseite und durch die sich verkleinernden Förderzellen 7 wird in der Zahnradkammer 4 eine Hochdruckseite gebildet.For fluid delivery, the inner gear 1 is rotationally driven by the drive shaft 8 forth, for example in the drawn direction of rotation D, and takes the outer gear 2 in the same direction D due to the meshing tooth engagement. During the rotational movement, the delivery cells 7 increase from a region of deepest meshing engagement, in the direction of rotation D, to a region of least meshing engagement, and decrease again from the region of lowest meshing engagement to the region of deepest meshing engagement. Due to the increasing delivery cells 7 is in the gear chamber 4, a low pressure side and by the decreasing delivery cells 7, a high pressure side is formed in the gear chamber 4.

Werden die beiden Zahnräder 1 und 2 drehangetrieben, so wird auf der Niederdruckseite auf Grund der dort expandierenden Förderzellen 7 Fluid über die Einlassöffnung 5 und die im Gehäusedeckel gegenüber liegend gebildete Einlassöffnung angesaugt und in den Förderzellen 7 über den Bereich geringsten Zahneingriffs auf die Hochdruckseite transportiert. Auf der Hochdruckseite verkleinern sich die Förderzellen 7, so dass das Fluid unter Druckerhöhung durch die Auslassöffnung 6 und die in dem Gehäusedeckel gegenüber liegend ausgebildete Auslassöffnung verdrängt wird und durch den sich an diese beiden Auslassöffnungen anschließenden Hochdruckkanal zu dem Gehäuseauslass und letztendlich zu einem mit dem Fluid zu versorgenden Aggregat strömt.If the two gearwheels 1 and 2 are rotationally driven, fluid is sucked in through the inlet opening 5 and the inlet opening formed in the housing cover on the low-pressure side due to the delivery cells 7 expanding there and transported in the conveyor cells 7 over the region of least meshing with the high-pressure side. On the high-pressure side, the delivery cells 7 shrink, so that the fluid is displaced by increasing the pressure through the outlet opening 6 and the outlet opening formed in the housing cover, and through the high-pressure channel adjoining these two outlet openings to the housing outlet and finally to one with the fluid to be supplied unit flows.

Das innere Zahnrad 1 der Innenzahnradpumpe ist in Fig. 2 in einer perspektivischen Darstellung und in Fig. 3 in der Ansicht der Fig. 1 einzeln dargestellt. In jedem der Zahnfüße der Außenverzahnung 1a sind zwei Vertiefungen 10 gebildet, die sich von einem axial mittleren Steg 11 ausgehend in axialer Richtung bis je zu einer der beiden Stirnseiten des inneren Zahnrads 1 erstrecken. Jede der Vertiefungen 10 mündet an nur einer der beiden Stirnseiten des Zahnrads 1. Die beiden pro Zahnfuß gebildeten Vertiefungen 10 enden in dem jeweiligen Zahnfuß und bilden zwischen sich den Steg 11. Der zwischen den Vertiefungen 10 im Grund eines jeden der Zahnfüße verbleibende Steg 11 kann als Zahnfußprofil in bekannter Weise gebildet sein, beispielsweise als Hypozykloide. Jeder der Stege 11 berührt den Fußkreis F der Außenverzahnung 1a, d.h. die Stege 11 bestimmen den Fußkreis F. Eingezeichnet ist in Figur 3 ferner der Wälzkreis W, der das Profil der Außenverzahnung 1a in Zahnköpfe und Zahnfüße teilt.The inner gear 1 of the internal gear pump is in Fig. 2 in a perspective view and in Fig. 3 in the view of Fig. 1 shown individually. In each of the tooth roots of the outer toothing 1a, two recesses 10 are formed, which extend from an axially central web 11, starting in the axial direction to one of the two end faces of the inner gear 1. Each of the recesses 10 opens at only one of the two end faces of the gear 1. The two recesses 10 formed per tooth root end in the respective tooth root and form between the web 11. The remaining between the recesses 10 in the bottom of each of the toothed web 11 can be formed as Zahnfußprofil in a known manner, for example as Hypozykloide. Each of the webs 11 touches the root circle F of the external toothing 1a, ie the webs 11 determine the root circle F. Is marked in FIG. 3 Further, the pitch circle W, which divides the profile of the external teeth 1a in tooth tips and tooth roots.

Die Vertiefungen 10 weisen im Querschnitt ein rundes Profil auf mit einer in Umfangsrichtung gemessenen Breite B. Die Vertiefungen 10 weisen ihre größte Breite B je an ihrer Mündungsstelle an der Stirnseite des inneren Zahnrads 1 auf. In Fig. 3 ist diese größte Breite B beispielhaft für eine der Vertiefungen 10 eingezeichnet. Ebenfalls eingezeichnet ist die Tiefe T im Scheitel des Zahnfußes beispielhaft für eine der Vertiefungen 10. Die Tiefe T wird in radialer Richtung gemessen und ist auf das in axialer Richtung über die Vertiefung 10 verlängert gedachte Zahnfußprofil der Stege 11 bezogen. Auch ihre größte Tiefe T weisen die Vertiefungen 10 an der Stirnseite des inneren Zahnrads 1 auf, an der sie münden. Von der Mündungsstelle an der Stirnseite bis zu dem Steg 11 nimmt die Tiefe T in axialer Richtung kontinuierlich ab.The depressions 10 have a round profile in cross-section with a width B measured in the circumferential direction. The depressions 10 each have their greatest width B at their discharge point on the end face of the inner gearwheel 1. In Fig. 3 This largest width B is shown as an example for one of the depressions 10. The depth T in the apex of the tooth root is also shown by way of example for one of the depressions 10. The depth T is measured in the radial direction and is related to the toothed profile of the webs 11 that has been extended in the axial direction over the depression 10. Also their greatest depth T, the recesses 10 on the end face of the inner gear 1, where they open. From the point of discharge at the end face to the web 11, the depth T decreases continuously in the axial direction.

Fig. 4 zeigt einen Bereich des inneren Zahnrads, in dem eine Vertiefung 10 gebildet ist, in einem Schnitt. Die Schnittebene ist die Axial/Radial-Ebene, die die Vertiefung 10 in zwei gleiche Hälften teilt. Die Vertiefung 10 weist in dieser Schnittebene ihre jeweils größte Tiefe T in der zur Axial/Radial-Schnittebene senkrechten Querschnittsebene auf. Die Vertiefung 10 flacht von der Stirnseite des inneren Zahnrads 1 bis zu dem Steg 11 kontinuierlich unter einem Neigungswinkel α ab. Der abflachende Verlauf der Vertiefung 10 ist ferner in einem geringen Ausmaß degressiv, das heißt der Neigungswinkel α, gemessen auf die axiale Verlängerung des Zahnfußprofils des Stegs 11, nimmt von der Stirnseite bis zu dem Steg 11 ebenfalls allmählich ab. Allerdings läuft die Vertiefung 10 in den Steg 11 schräg ein, das heißt der Neigungswinkel α ist im Übergangsbereich zwischen Vertiefung 10 und Steg 11 ungleich "0". Fig. 4 shows a portion of the inner gear, in which a recess 10 is formed, in a section. The cutting plane is the axial / radial plane which divides the recess 10 into two equal halves. In this sectional plane, the depression 10 has its respectively greatest depth T in the cross-sectional plane perpendicular to the axial / radial cutting plane. The recess 10 flattens from the end face of the inner gear 1 to the web 11 continuously at an inclination angle α. The flattening course of the recess 10 is further degressive to a small extent, that is, the inclination angle α, measured on the axial extension of the Zahnfußprofils the web 11, from the front side to the web 11 is also gradually from. However, the depression 10 runs obliquely into the web 11, that is to say the angle of inclination α is unequal to "0" in the transition region between the depression 10 and the web 11.

Wie am besten in Fig. 2 zu erkennen ist, werden die Vertiefungen 10 je von einer glatten Mantelfläche im Grund von jedem der Zahnfüße gebildet. Die Vertiefungen 10 sind je kegelförmig mit einem in einer radialen Draufsicht runden Übergangsbereich in das von dem jeweiligen Steg 11 gebildete Zahnfußprofil. Die Erzeugende des von jeder der Vertiefungen 10 gebildeten Kegels ist wegen des sich ändernden Neigungswinkels α ein wenig gekrümmt. Die Form könnte daher auch als hyperboloid bezeichnet werden. Eine gerade Kegelform wäre ebenfalls möglich. Die in axialer Richtung nach radial auswärts konkave Form der Vertiefungen 10 ergibt jedoch pro Vertiefung 10 ein vorteilhaft großes Verhältnis von Mündungsquerschnittsfläche zu Volumen.How best in Fig. 2 can be seen, the recesses 10 are each formed by a smooth lateral surface in the base of each of the tooth roots. The recesses 10 are each conical with a round in a radial plan view transition region in the formed by the respective web 11 Zahnfußprofil. The generatrix of the cone formed by each of the recesses 10 is slightly curved because of the changing inclination angle α. The shape could therefore also be called hyperboloid. A straight cone shape would also be possible. The axially outwardly radially concave shape of the However, depressions 10 results per well 10 an advantageously large ratio of mouth cross-sectional area to volume.

Im Ausführungsbeispiel sind die Vertiefungen 10 exakt im Scheitel der Zahnfüße gebildet, mit der den Fußkreis F im Scheitel schneidenden Axial/Radial-Ebene als Symmetrieebene. Hiervon abweichende Formen sind jedoch ebenfalls denkbar. Vorteilhaft ist es allerdings, wenn die Mündungen der Vertiefungen 10 an der Stirnseite des inneren Zahnrads 10 in dieser Weise geformt und angeordnet sind. Von diesen Mündungen aus können die Vertiefungen 10 jedoch durchaus auch gerade schräg oder bogenförmig zu der Axialen zum jeweiligen Steg 11 hin auslaufen, um die Einströmverhältnisse in die betreffende Förderzelle 7 zu beeinflussen.In the exemplary embodiment, the depressions 10 are formed exactly at the apex of the tooth feet, with the root circle F cutting in the apex axial / radial plane as the plane of symmetry. However, deviating forms are also conceivable. It is advantageous, however, if the mouths of the recesses 10 are formed and arranged on the end face of the inner gear 10 in this way. From these mouths, however, the depressions 10 may well also run straight obliquely or arcuately to the axial to the respective web 11 in order to influence the Einströmverhältnisse in the relevant conveyor cell 7.

Die Einlassöffnung 5 und die Auslassöffnung 6 sind in der hinteren Kammerstirnwandung als nierenförmige Öffnungen ausgenommen. Sie erstrecken sich in Umfangsrichtung je über mehrere Förderzellen 7, wobei sie die betreffenden Förderzellen 7 radial überdecken. Die Einlassöffnung 5 überdeckt ferner radial auch die Vertiefungen 10. Die Auslassöffnung 6 erstreckt sich radial nur bis zu dem Fußkreis der Außenverzahnung 1a, so dass unmittelbar aus den Vertiefungen 10 kein Fluid verdrängt wird. Das zu der Einlassöffnung 5 und der Auslassöffnung 6 gesagte gilt auch für die Einlassöffnung und die gegebenenfalls vorhandene Auslassöffnung in dem abgenommenen Gehäusedeckel. In dem Gehäusedeckel kann, muss jedoch keine Auslassöffnung gebildet sein. Bei der Drehbewegung der Zahnräder 1 und 2 überstreichen daher die Vertiefungen 10 die Einlassöffnung 5 und die axial zugewandt gegenüber liegende Einlassöffnung in dem Gehäusedeckel.The inlet opening 5 and the outlet opening 6 are recessed in the posterior Kammerstirnwandung as kidney-shaped openings. They extend in the circumferential direction depending on several conveyor cells 7, wherein they cover the respective conveyor cells 7 radially. The inlet opening 5 also radially overlaps the depressions 10. The outlet opening 6 extends radially only up to the root circle of the external toothing 1a, so that no fluid is displaced directly from the depressions 10. The comments made regarding the inlet opening 5 and the outlet opening 6 also apply to the inlet opening and the optionally existing outlet opening in the removed housing cover. In the housing cover, but no outlet opening must be formed. During the rotational movement of the toothed wheels 1 and 2, therefore, the recesses 10 sweep the inlet opening 5 and the axially opposite inlet opening in the housing cover.

In den Fig. 5 und 6 ist der volumetrische Wirkungsgrad E über der Drehzahl R des angetriebenen Zahnrads 1 aufgetragen. Fig. 5 zeigt den Verlauf des volumetrischen Wirkungsgrads E für eine Innenzahnradpumpe mit einem Zahnradlaufsatz ohne Vertiefungen, und Fig. 6 zeigt zum Vergleich den volumetrischen Wirkungsgrad E für eine Innenzahnradpumpe nach der Erfindung. Im dargestellten Beispielfall bildet die Innenzahnradpumpe die Schmierölpumpe für einen Verbrennungshubkolbenmotor eines PKW oder LKW. Dies ist ein besonders bevorzugtes Verwendungsbeispiel für eine erfindungsgemäße Innenzahnradpumpe. Die Einbausituation der Pumpe ist hierbei so, dass das angetriebene Zahnrad, im Beispielfall das innere Zahnrad 1, mit einer Drehzahl R von bis zu 14.000 Umdrehungen pro Minute (U/min) angetrieben wird, das heißt es wird von einer Kurbelwelle des Motors aus mit einer gegenüber der Kurbelwelle übersetzten Drehzahl angetrieben. Ab einer Antriebsdrehzahl von etwa 7.000 U/min setzt bei der herkömmlichen Pumpe die Kavitation ein. Ein Pfeil K deutet auf den Kavitationsbeginn. Mit weiter zunehmender Drehzahl sinkt der volumetrische Wirkungsgrad E ab.In the FIGS. 5 and 6 the volumetric efficiency E is plotted against the speed R of the driven gear 1. Fig. 5 shows the curve of the volumetric efficiency E for an internal gear pump with a gear set without recesses, and Fig. 6 shows for comparison the volumetric efficiency E for an internal gear pump according to the invention. In the illustrated example case, the internal gear pump forms the lubricating oil pump for a Verbrennungshubkolbenmotor a car or truck. This is a particularly preferred example of use for an internal gear pump according to the invention. The installation situation of the pump is in this case such that the driven gear, in the example, the inner gear 1, with a speed R of up to 14,000 revolutions per minute (RPM) is driven, that is, it is from a crankshaft of the engine with a relation to the crankshaft translated speed driven. From a drive speed of about 7,000 rpm, the conventional pump uses cavitation. An arrow K indicates the beginning of cavitation. As the speed increases, the volumetric efficiency E decreases.

Der volumetrische Wirkungsgrad E einer mit Ausnahme der erfindungsgemäßen Vertiefungen 10 baugleichen Innenzahnradpumpe ist in der Fig. 6 im Vergleich aufgetragen. Der Kavitationsbeginn K kann zu deutlich höheren Drehzahlen verschoben werden. im Vergleichsfall konnte der Kavitationsbeginn K zu einer um etwa 2.000 U/min höheren Drehzahl verschoben werden. Ferner sinkt der volumetrische Wirkungsgrad E in dem sich nach oben daran anschließenden Drehzahlbereich trotz Kavitation weniger stark ab als bei der herkömmlichen Innenzahnradpumpe ohne Vertiefungen.The volumetric efficiency E of an internal gear pump identical in construction to those of the recesses 10 according to the invention is shown in FIG Fig. 6 applied in comparison. The beginning of cavitation K can be shifted to significantly higher speeds. In the comparison case, the start of cavitation K could be shifted to a speed higher by about 2,000 rpm. Furthermore, the volumetric efficiency E in the upwardly adjoining speed range, despite cavitation, decreases less sharply than in the case of the conventional internal gear pump without recesses.

Claims (9)

  1. An internal toothed wheel pump, comprising:
    a) a housing (3);
    b) a toothed wheel chamber (4) which is formed in the housing (3) and comprises an inlet opening (5) on a low-pressure side and an outlet opening (6) on a high-pressure side, for a fluid;
    c) an inner toothed wheel (1) which is accommodated in the toothed wheel chamber (4) and can be rotated about a rotational axis (D1) and comprises an external toothing (1a);
    d) an outer toothed wheel (2) which is accommodated in the toothed wheel chamber (4) and comprises an internal toothing (2i), which is in a mating toothed engagement with the external toothing (1a), and forms expanding delivery cells (7) on the low-pressure side and compressing delivery cells (7) on the high-pressure side with the external toothing when the toothed wheels (1, 2) are rotary-driven;
    e) wherein the internal toothing (2i) of the outer toothed wheel (2) comprises at least one tooth more than the external toothing (1a) of the inner toothed wheel (1),
    f) and wherein in roots of the teeth of the external toothing (1a), at least one recess (10) is formed in the base of the root of each tooth, wherein said recess extends as far as a front face of the external toothing (1a) and exhibits a greater radial depth (T) at the front face than in an inner region of the base of the root of the tooth which is axially spaced from the front face,
    g) and wherein the inlet opening (5) which lies axially opposite and facing the front face of the external toothing (1a) covers the delivery cells (7) and the recesses (10), characterised in that
    h) the outlet opening (6) on the high-pressure side, which lies axially opposite and facing the front face of the external toothing (1a), covers the delivery cells (7) but not the recesses (10).
  2. The internal toothed wheel pump according to claim 1, characterised in that in roots of the teeth of the external toothing (1a), at least one recess (10) is formed in the base of the root
    of each tooth, wherein said recess extends as far as the other front face of the external toothing (1a) and exhibits a greater radial depth (T) at the other front face than in an inner region of the base of the root of the tooth which is axially spaced from the other front face.
  3. The internal toothed wheel pump according to any one of the preceding claims, characterised in that the depth (T) of the recesses (10) increases continuously towards the front face.
  4. The internal toothed wheel pump according to any one of the preceding claims, characterised in that the recesses (10) are concave radially outwards in the axial direction.
  5. The internal toothed wheel pump according to any one of the preceding claims, characterised in that the recesses (10) extend as far as a stay (11) which remains from a tooth profile in the inner region of the respective base of the root of the tooth and preferably forms the axial centre of the external toothing (1a).
  6. The internal toothed wheel pump according to any one of the preceding claims, characterised in that the recesses (10) widen towards the front face as far as which they extend.
  7. The internal toothed wheel pump according to any one of the preceding claims, characterised in that the recesses (10) are concave radially outwards in cross-section.
  8. The internal toothed wheel pump according to the preceding claim, characterised in that the recesses (10) are hyperboloid.
  9. The internal toothed wheel pump according to any one of claims 1 to 3 or 5 to 7, characterised in that the recesses are conical with a generatrix which is linear or curved in the axial direction.
EP03020503A 2002-10-01 2003-09-15 Internal gear pump with improved filling Expired - Lifetime EP1406015B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10245814A DE10245814B3 (en) 2002-10-01 2002-10-01 Internal-gear pump e.g. for pumping engine oil has at least one recess in feet of external teeth extending to one endface of external teeth
DE10245814 2002-10-01

Publications (2)

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EP1406015A1 EP1406015A1 (en) 2004-04-07
EP1406015B1 true EP1406015B1 (en) 2011-07-20

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AT (1) ATE517261T1 (en)
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JP2006125391A (en) * 2004-09-28 2006-05-18 Aisin Seiki Co Ltd Rotor structure for internal gear pump
DE102006047312A1 (en) * 2006-10-06 2008-04-10 Sauer-Danfoss Aps Hydraulic machine
GB0620646D0 (en) * 2006-10-18 2006-11-29 Concentric Vfp Ltd Pumps with filling slots
DE102007040724A1 (en) 2007-08-29 2009-03-05 Robert Bosch Gmbh delivery unit
DE102008003843A1 (en) 2008-01-10 2009-07-16 Robert Bosch Gmbh delivery unit
WO2009130433A1 (en) * 2008-04-22 2009-10-29 Concentric Vfp Limited Pump with filling slots
JP5591049B2 (en) * 2010-09-30 2014-09-17 富士重工業株式会社 Internal gear type fluidic device
DE102012022787A1 (en) 2012-11-22 2014-05-22 Volkswagen Aktiengesellschaft Internally controlled gear pump used in pressurized control system, has axial grooves that extend axially over entire length of inner rotor, where ratio of radius of outer tooth root surface and radius of groove is of specific value
JP6382674B2 (en) * 2014-10-07 2018-08-29 豊興工業株式会社 Internal gear pump
US10563653B2 (en) 2016-01-12 2020-02-18 Hamilton Sundstrand Corporation Gear pump

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GB370474A (en) * 1930-12-11 1932-04-11 Thomas Winter Nichols Improvements in rotary pumps
FR977730A (en) * 1942-10-23 1951-04-04 Method and devices for balancing the pinions of gear pumps
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DE2829417C3 (en) * 1978-07-05 1984-07-12 Mannesmann Rexroth GmbH, 8770 Lohr Work equipment control for a parallel and internal-axis rotary piston machine
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ES2369901T3 (en) 2011-12-09
EP1406015A1 (en) 2004-04-07
DE10245814B3 (en) 2004-02-12
ATE517261T1 (en) 2011-08-15

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