Note: Within nine months of the publication of the mention of the grant of the European patent in the European PatentBulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with theImplementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has beenpaid. (Art. 99(1) European Patent Convention).

Printed by Jouve, 75001 PARIS (FR)

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(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention of the grant of the patent: 16.03.2016 Bulletin 2016/11

(21) Application number: 12815823.5

(22) Date of filing: 11.12.2012

(51) Int Cl.:F04C 14/22 (2006.01)

(86) International application number: PCT/IB2012/057167

(87) International publication number: WO 2013/093711 (27.06.2013 Gazette 2013/26)

(54) ROTARY POSITIVE DISPLACEMENT PUMP AND METHOD OF REGULATING ITS DISPLACEMENT

ROTATIONSVERDRÄNGERPUMPE UND VERFAHREN ZUR STEUERUNG VON DEREN VERDRÄNGUNG

POMPE VOLUMÉTRIQUE ROTATIVE ET MÉTHODE DE RÉGULATION DE SON DÉBIT VOLUMÉTRIQUE

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30) Priority: 22.12.2011 IT TO20111188

(43) Date of publication of application: 29.10.2014 Bulletin 2014/44

(73) Proprietor: VHIT S.p.A.26010 Offanengo (CR) (IT)

(72) Inventors: • CORTESI, Matteo

I-26010 Offanengo (CR) (IT)• STAGNOLI, Luca

I-26010 Offanengo (CR) (IT)

(74) Representative: Robba, PierpaoloInterpatent S.R.L. Via Caboto 3510129 Torino (IT)

(56) References cited: WO-A1-2005/068838 JP-A- 53 148 703US-A1- 2008 038 117

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Description

Technical field

[0001] The present invention relates to variable dis-placement pumps, and more particularly it concerns arotary positive displacement pump in which the displace-ment variation is obtained by means of the translation ofa stator ring inside which the pump rotor eccentricallyrotates.[0002] Preferably, but not exclusively, the present in-vention is employed in a pump for the lubrication oil of amotor vehicle engine.

Prior Art

[0003] It is known that, in pumps for making lubricatingoil under pressure circulate in motor vehicle engines, thepump capacity, and hence the oil delivery rate, dependson the rotation speed of the engine. Hence, the pumpsare designed so as to provide a sufficient delivery rateat low speeds, in order to ensure lubrication also undersuch conditions. If the pump has fixed geometry, at highrotation speed the delivery rate exceeds the necessaryrate, giving rise to a high power absorption, and conse-quently to higher fuel consumption, and to a greaterstress of the components due to the high pressures gen-erated in the circuit.[0004] In order to obviate this drawback, it is known toprovide the pumps with systems allowing a delivery rateregulation at the different operating conditions of the ve-hicle, in particular through a displacement regulation. Dif-ferent solutions are known to this aim, which are specificfor the particular kind of pumping elements (external orinternal gears, vanes...). Some general kinds of displace-ment regulation systems can however be identified, andone such system is based on the translation of an element(stator ring), which is arranged in a cavity of the pumpbody and surrounds the rotor with an eccentricity depend-ing on the position taken by the same ring due to its trans-lation.[0005] Examples of pumps of such kind are disclosedin US 2004247643, US 2008038117, WO2005068838A1and EP 1600637.[0006] In particular, WO2005068838A1 discloses apositive displacement pump with a vane rotor, in whichthe stator ring is made to slide in response to the pressuredifference in two chambers located at opposite sides ofthe stator ring and connected to the delivery side of thepump, one chamber directly and the other one througha control valve. The translation is guided by the samemembers on which the pressure controlling translationacts.[0007] This prior art pump has a number of problemsthat mainly affect just the ring and concern in particular:

- feasibility: given the manner in which the stator ringof the prior art pump is kept in position against the

action of the internal pressures generated by thepump operation and is guided during translation, par-ticular mechanical tolerances and surface conditionsare required in order to allow the proper displace-ment without sticking and without leaks;

- pressure stability: the pressure controlling the dis-placement of the stator ring is the pressure at thedelivery side, and this entails that the system is con-siderably sensitive to the pressure fluctuations, typ-ical of positive displacement pumps, present at thepump delivery side;

- wear: due to the pressures acting on the stator ringand the resulting sticking possibility, high wears oc-cur between the contacting parts in the ring and thepump body.

[0008] Pumps with a similar stator ring, originating thesame problems, are disclosed in US 2004247643 andUS 2008038117[0009] It is an object of the present invention to providea pump in which the displacement is regulated by meansof the translation of the stator ring, and a method of reg-ulating the displacement of such a pump, which obviatethe drawbacks of the prior art.

Description of the invention

[0010] According to the invention, this is obtained inthat the stator ring includes guiding means arranged toslide in a guiding chamber formed in the pump body andpreferably communicating with a pressure zone of thepump in order to receive fluid under pressure therefrom,and in that the guiding means, during the translation ofthe stator ring, are arranged to be pushed by the fluidunder pressure into sealing contact with a surface of theguiding chamber and, in a zone of contact with such asurface, they have a curvature with such a radius that ahomogeneous contact pressure distribution is ensuredas the operating conditions of the pump and, consequent-ly, the position of the stator ring, vary.[0011] Advantageously, the guiding means comprisea pair of fins, which extend substantially tangentially tothe stator ring and in opposite directions from an outersurface of the ring, define a common push surface thatis acted upon by the fluid under pressure and a pair ofcontact areas each having the radius of curvature ensur-ing the homogeneous contact pressure distribution, andhave rounded free ends.[0012] In this manner, the possibility of sticking and theresulting wear are drastically reduced. Moreover, theneed for sealing elements is eliminated.[0013] The translation may be mechanically controlled,by the action of the pressures in a circuit utilising thepumped fluid, or electronically controlled, by means of amotor controlled by an electronic control unit detectingthe conditions of the same fluid in a utilisation circuit.[0014] The invention also implements a method of reg-ulating the displacement of a rotary positive displacement

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pump by means of the translation of a stator ring insidewhich the pump rotor eccentrically rotates. According tosuch a method, such a translation is guided by guidingmeans arranged to slide in contact with a surface of aguiding chamber, formed in the pump body, due to theaction of a pressurised fluid preferably coming from thedelivery side of the pump, and the guiding means aremade to contact the surface of the guiding chamber at azone of the surface of the guiding means having a cur-vature with such a radius that a homogeneous contactpressure distribution is ensured as the operating condi-tions of the pump and, consequently, the position of thestator ring, vary.[0015] According to a further aspect of the invention,there is also provided a lubrication system for a motorvehicle engine, in which the adjustable displacementpump and the method of regulating the displacement setforth above are employed.

Brief Description of the Figures

[0016] Further features and advantages of the inven-tion will become clearly apparent from the following de-scription of preferred embodiments, given by way of nonlimiting examples with reference to the accompanyingdrawings, in which:

- Fig. 1 is an axial sectional view of a pump accordingto the invention;

- Fig. 2 is a front view of the pump, without the frontcover, showing the stator ring in the maximum dis-placement position;

- Figs. 3 and 4 are enlarged views of details A and Bof Fig. 2;

- Figs. 5 and 6 are cross-sectional views of the pump,showing the stator ring in the maximum displace-ment and minimum displacement positions, respec-tively;

- Figs. 7 and 8 are enlarged views of details of theguiding fins of the stator ring; and

- Figs. 9 to 11 are diagrams of a lubrication circuit ofa motor vehicle engine using the pump according tothe invention, in different operating conditions.

Description of Preferred Embodiments

[0017] Referring to Figs. 1 to 6, reference numeral 1generally denotes a rotary positive displacement pumpwith adjustable displacement, in particular a pump for thelubrication oil of a motor vehicle engine, of a kind com-prising a body 2 in which a chamber 3 housing a statorring 4 is formed. Ring 4 has an internal cavity 40 in whichrotor 5 eccentrically rotates and it can be translated trans-versally to its axis in order to regulate the pump displace-ment. Rotor 5 is for instance a vane rotor, vanes 6 ofwhich are radially slidable in radial slots 7, and it is drivenby a suitably shaped shaft (not shown), which is insertedin a cavity 10 of complementary shape. A centring ring

11 is mounted at each of both axially opposite ends ofrotor 5 in order to keep the vanes in contact with theinternal surface of ring 4 at low temperature and/or lowspeed.[0018] Chamber 3 is closed by a front cover 41 and arear cover 42. Channels 8, 9 for oil suction from the sumpand oil delivery towards the oil filter, as well as lubricationchannels (not shown in the drawing), are formed in rearcover 42.[0019] Suction channel 8 communicates, through achamber 45 in rear cover 42, with suction chambers 43,44 formed for instance in the lower part of chamber 3 andof internal cavity 40 of the stator ring 4, respectively.Chambers 43, 44 also communicate with each otherthrough a chamber 46 formed in front cover 41. Such asupply on both sides of the rotor of pump 1, which canalso be referred to as "double supply", allows the pumpto operate in conditions of absence of cavitation up tohigh rotation speeds.[0020] Oil is sent in conventional manner from suctionchamber 44 to a delivery chamber 47 formed in cavity40 and communicating in turn with delivery channel 9.[0021] Chamber 43 preferably allows collecting possi-ble oil leaks inside pump 1, coming from delivery chamber47 or generally from spaces under pressure, as it will bedisclosed later on.[0022] Chamber 43, if it is located at a lower level thanchannel 8, also prevents the pump from emptying at thestart from a stationary condition, after a long stop.[0023] In the illustrated embodiment, the translation ofring 4, which, by way of example, is supposed to takeplace horizontally, is controlled by the oil pressure in theengine lubrication circuit, as it will be disclosed later on.[0024] The translation of ring 4 is caused by a pair ofsubstantially cylindrical push heads 13, 14, which act ontwo diametrically opposite areas of ring 4. Advantageous-ly, the contacting surfaces in heads 13, 14 and ring 4 areflat surfaces, as shown in Fig. 3 for head 14. A flat contactsurface does not demand special workings. A projection12 in the wall of chamber 3 acts as a stop for the maximumdisplacement stroke and it is arranged to maintain, insuch a condition, a certain clearance between ring 4 androtor 5, as it is better visible in Fig. 4. The position takenby ring 4 in the condition of maximum displacement ofthe pump is also the reference position for mounting thering into seat 3.[0025] Heads 13, 14 are mounted in body 2 so as tobe slidable in respective chambers 15, 16, which areclosed by plugs 17 and 18 and which receive pressurisedoil from the lubrication circuit of the engine either directly(chamber 16) or through a regulation valve 19 (chamber15), also controlled by the oil pressure in the lubricationcircuit.[0026] The first push head 13 is also biased by a spring20 that is preloaded so that head 13 keeps ring 4 in aposition of maximum displacement of the pump (Figs. 2,5) under low oil pressure conditions, in particular at themotor start. The flat surfaces of head 13 and ring 4 in

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their contacting zones allow a homogeneous distributionof the force generated by spring 20 on ring 4.[0027] The second head 14 is actuated to displace ring4 from the maximum displacement position towards theminimum displacement position when oil pressure inchamber 16 exceeds the preload of spring 20, and it ispushed backwards by ring 4 when the latter moves backto the maximum displacement position as oil pressure inchamber 16 decreases. Thanks to a spacer 21, whichmay also be integrally formed with head 14, the latter isalways kept in contact with ring 4 and does not adhereto plug 18.[0028] Regulation valve 19 may be made to slide par-allel to the displacement direction of ring 4, in order tomanage the regulation pressures, thanks to a pair of pushsurfaces 19a, 19b which are acted upon by the oil pres-sure. A spring 24 tends to maintain valve 19 in the positionrequired in order ring 4 remains in the maximum displace-ment position. Valve 19 may be integrated into pumpbody 2, in a seat 22 closed by a plug 23, as shown inFigs. 5, 6, or in the engine block, depending on the par-ticular engine. In any case, body 2 will be provided withseat 22 independently of the actual presence of the valve,so that a same pump body can always be utilised.[0029] The connections of chambers 15, 16 and reg-ulation valve 19 to the lubrication circuit will be disclosedlater on.[0030] Ring 4 is so shaped as to have a guiding mem-ber, advantageously consisting of a pair of fins 25 formedfor instance in the top portion of ring 4. The fins extendsubstantially tangentially to the ring in opposite directionsand they are housed in a guiding chamber 26 formed inbody 2 and communicating with delivery channel 9. Dur-ing the translation of ring 4, fins 25 slide in contact withthe walls of chamber 2 and the contact is ensured by thepressure of oil picked up from delivery channel 9 andacting on top faces 27 of fins 25, defining a common pushsurface. The communication between delivery channel9 and chamber 26 is obtained through a duct (not visiblein the drawing) formed by means of a suitable workingof rear cover 41 and/or body 2.[0031] The shape of contact area 29 between each fin25 and body 2 is such as to counterbalance the pressureforces generated inside the pump during operation andto maintain the contact with body 2 in a limited area inany operating condition. In this manner, there is no needfor sealing elements. In particular, as shown in Fig. 7,fins 25 contact body 2 according to a curved surface hav-ing a curvature with relatively wide radius R designed soas:

- to keep the contact pressure within acceptable limits(cylinder-to-plane contact) without giving rise to up-setting of the material in the region underneath;

- to ensure a homogeneous contact pressure distri-bution as the operating conditions vary, notwith-standing fins 25, as the pressure applied thereto in-creases, bend with a consequent displacement of

the contact points.

[0032] Moreover, the free ends of fins 25 have a round-ed shape, designed so as to avoid that, due to the forcesexerted by the moving fins or by internal overpressures(which could bring the fins in contact with the upper sur-face of chamber 26, Fig. 8), ring 4 is blocked in case ofan unbalance due to an overpressure surge within thepump.[0033] Referring to Figs. 9 to 11, lubrication circuit 100of a motor vehicle engine 30 using pump 1 is shown.Reference numerals 31 and 32 denote the oil sump andthe oil filter, connected in conventional manner to thesuction and delivery channels 8 and 9 (Fig. 1), throughducts also denoted by reference numerals 8 and 9. Ref-erence numeral 33 denotes the outlet duct of filter 12,conveying oil to engine 30. These Figures show an em-bodiment in which regulation valve 19 is external to pumpbody 2. Such an embodiment allows more clearly seeingthe connections of valve 19 with lubrication circuit 100and with the rest of pump 1.[0034] A branch 9a of delivery channel 9 conveys oilinto chamber 26 in order to push fins 25 into contact withthe base of chamber 26. As stated before, such a branchactually is a duct formed internally of the pump body. Afirst branch 33a of duct 33 forms a first regulation ductconveying pressurised oil to chamber 16. A second anda third branch 33b, 33c of the same duct convey oil to afirst and a second inlet 49a, 49b of valve 19. Oil fed tothe first inlet 49a preferably acts on the first push surface19a in order to control the possible displacement of valve19, whereas oil fed to the second inlet 49b may be trans-ferred either to a second regulation duct 35, communi-cating with chamber 15, or to exhaust 37. The secondbranch 33b conveys oil also to a distribution valve 36, forinstance an electromagnetic valve. Depending on the po-sition of this valve, oil leaving filter 32 may be conveyed,through a duct 34, to a third inlet 49c of valve 19, whereoil acts on a second push surface 19b, or oil present invalve 19 in correspondence of inlet 49c may be sent backto oil sump 31 (duct 38).[0035] In accordance with other embodiments, oil fedto the first inlet 49a and to the third inlet 49c may act inreversed manner, for instance so that the first inlet 49aand the third inlet 49c act on the second push surface19b and the first push surface 19a, respectively.[0036] Thanks to the provision of distribution valve 36and by properly dimensioning push surfaces 19a and19b, it is possible to obtain two or more different inter-vention points for regulation valve 19.[0037] It is to be appreciated that, depending on therequirements of the pump users, the regulation pressures(ducts 33a and 33c) could be taken from delivery channel9 instead of being taken from outlet duct 33 of the filter.Yet, the illustrated solution is the solution ensuring thegreatest stability in the regulation pressure since, asknown, due the nature of the positive displacementpumps, the delivery pressure has surges that are

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smoothed by filter 32. On the contrary, it is preferable todirectly take the pressure acting on fins 25 from the de-livery side, in order to constantly ensure the contact be-tween the fins and pump body 2, even if other embodi-ments are possible.[0038] It is also to be appreciated that, if valve 19 islocated in pump body 2, ducts 33a, 33b, 34 35 will beformed, at least in part, in body 2 by means of a suitableworking, in similar manner to what has been stated forthe duct putting delivery channel 9 in communication withchamber 26.[0039] The operation of pump 1 is as follows.[0040] When the motor is started, there is a low oil pres-sure at the delivery side and the pump is in the maximumdisplacement condition (Fig. 9). Under such a condition,the preload of spring 24 pushes valve 19 wholly to theleft, so that oil can pass from inlet 49b to duct 35 andhence into chamber 15. In opposition to the reaction pro-duced by the pressure sent into that chamber, the firstregulation duct 33a picks up pressure downstream filter32 and sends it to chamber 16. Due to a force balancein the direction in which push heads 13, 14 act, ring 4 isin contact with mechanical stop 12 (Figures 2, 3).[0041] During the operation of pump 1, the pressureat outlet 33 from filter 32 (and hence at inlet 49a of valve19) increases and, once it has exceeded a given thresh-old, it overcomes the preload of spring 24, thereby mak-ing valve 19 displace to the right. The displacement ofvalve 19 progressively closes inlet 49b and puts chamber15 in communication with exhaust 37. In this manner, thepressure in chamber 15 decreases and the pressure inchamber 16 can overcome the preload of spring 21 anddisplace ring 4 proportionally to the pressure drop inchamber 15. Of course, the displacement of ring 4 endswhen the minimum displacement position is reached(Fig. 10).[0042] As the pressure in duct 33 decreases, it is pos-sible to resume the maximum displacement positionthanks to the displacement of valve 19 to the left causedby spring 24. By such a displacement, the communicationbetween inlet 49b and regulation duct 35 is restored andthe pressure always present in chamber 16 can no longerovercome the combined action of the pressure in cham-ber 15 (which pressure is being progressively restored)and of spring 21.[0043] If an intervention of valve 19 at a pressure leveldifferent from the high pressure level described above isdesired, electromagnetic valve 36 will be actuated so asto apply the pressure existing at outlet 33 of filter 32 alsoto inlet 49c of valve 19 (Fig. 11). The push is now exertedon both push surfaces 19a, 19b and hence the preloadof spring 20 can be overcome by a pressure lower thanthe previous one. It is clear for the skilled in the art thatvalve 36 also allows obtaining also multiple actuation lev-els different from the high pressure level for regulationvalve 19.[0044] Thanks to the peculiar shape of ring 4, the in-vention actually solves the problems mentioned above

of the prior art.[0045] Indeed, the mechanical and/or geometrical tol-erances and the surface conditions suitable for ensuringthe proper sliding of ring 4 only concern the small contactzone between ring 4 and body 2 (that is, between fins 25and guide 26), whereas the whole remaining surface ofthe fins may remain raw. Also a special working of thering surface zones in contact with push heads 13, 14 isnot required. This allows reducing the manufacturingcosts.[0046] Moreover, the wide radius R in zone 28 allowsreducing the contact pressure and, as the pressure actingon ring 4 varies during operation, it allows displacing thecontact point while keeping the shape of the contact pres-sure distribution constant. This prevents sticking andwear of the parts in relative movement, always possiblein the prior art. Also the rounded shapes of the ends offins 25 contribute to avoiding sticking during the normalsliding of ring 4 or during possible unbalances of samedue to overpressure surges inside the pump.[0047] On the other hand, the constant contact be-tween fins 25 and body 2 eliminates the need for sealingelements in order to avoid excessive oil leaks, therebycontributing to the constructional simplicity and hence tothe limitation of the manufacturing costs. The lack of seal-ing elements moreover assists in having a faster systemresponse to the displacement variation signal.[0048] It is clear that the above description has beengiven only by way of non-limiting example and that chang-es and modifications are possible without departing fromthe scope of the invention.[0049] For instance, even if in the illustrated embodi-ment the displacement of ring 4 is mechanically control-led by the pressures in the lubrication circuit, an electroniccontrol is also possible, through a small electric motor(brushless, three-phase synchronous or step-by-stepmotor) directly connected to ring 4 through a lever sys-tem, a mechanical coupling or another linkage arrangedto convert the rotary movement of the motor into a trans-latory movement. The motor will be electronically con-trolled by the electronic control unit of the motor vehicle,thereby ensuring a greater accuracy and a greater read-iness in the intervention. The advantage of this solutionis related to the possibility of having a continuous dis-placement variation in any condition of use, at any speedand temperature at infinite pressure levels.[0050] Lastly, even if the invention has been disclosedin detail with reference to a pump for the lubrication oilof a motor vehicle engine, it may be applied to any positivedisplacement pump for conveying fluid from a first to asecond working environment, in which a delivery rate re-duction as the pump speed increases is convenient

Claims

1. A rotary positive displacement pump for fluids, com-prising a rotor (5) arranged to eccentrically rotate in

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a chamber (40) defined within a stator ring (4), whichis located in a seat (3) formed in a pump body (2)and is connected to means (13, 14, 15, 19) for trans-lating such a ring relative to the rotor (5), as the op-erating conditions of the pump (1) vary, in order tochange the pump displacement, wherein the statorring (4) includes guiding means (25) arranged toslide in a guiding chamber (26) formed in the pumpbody (2) and communicating with a pressure zoneof the pump (1) or with utilisation devices (100) of apumped fluid, in order to receive fluid under pressuretherefrom, characterised in that the guiding means(25), during the translation of the stator ring (4), arearranged to be pushed by the fluid under pressureinto sealing contact with a surface of the guidingchamber (26) and, in a zone (28) of contact with sucha surface, they have a curvature with such a radiusof curvature (R) that a homogeneous contact pres-sure distribution is ensured as the operating condi-tions of the pump (1) and, consequently, the positionof the stator ring (4), vary.

2. The pump as claimed in claim 1, wherein the guidingmeans (25) comprise a pair of oppositely directedfins (35) extending substantially tangentially to thestator ring (4) from an outer surface of the stator ring(4) and defining a common push surface (27) that isacted upon by the fluid under pressure and a pair ofcontact areas (28) each having said curvature withsuch a radius of curvature (R) that the homogeneouscontact pressure distribution is ensured.

3. The pump as claimed in claim 2, wherein the fins(25) have rounded free ends.

4. The pump as claimed in any of claims 1 to 3, whereinthe translation of the stator ring (4) is controlled bya first and a second push head (13, 14), which acton diametrically opposite areas of the ring and arearranged to slide in a first and a second push cham-ber (15, 16), respectively, which chambers are dis-tinct from the guiding chamber (26) and communi-cate with the pressure zone of the pump (1) or, pref-erably, with the utilisation devices (100) of thepumped fluid, through a regulation valve (19) or di-rectly, respectively.

5. The pump as claimed in claim 4, wherein the regu-lation valve (19) is integrated in the pump (1).

6. The pump as claimed in claim 4 or 5, wherein thepush heads (13, 14) are arranged to separate a suc-tion environment (43) of the pump from a high pres-sure environment where the guiding means (25)slide.

7. The pump as claimed in any of claims 1 to 3, whereinthe translation of the stator ring (4) is controlled by

an electric motor.

8. The pump as claimed in any preceding claim, where-in the pump (1) is a pump for the lubrication circuit(100) of an engine of a motor vehicle.

9. A method of regulating the displacement of a rotarypositive displacement pump (1), comprising thesteps of:

- translating, relative to a rotor (5) of the pump(1), a stator ring (4) inside which the rotor (5)eccentrically rotates;- guiding the translation of the stator ring (4)through guiding means (25) arranged to slide ina guiding chamber (26) formed in a pump body(2) and communicating with a pressure zone ofthe pump (1) or with utilisation devices (100) ofthe pumped fluid;

the method being characterised in that it furthercomprises the steps of:

- making the pumped fluid act upon the guidingmeans (25) in order to keep them in sealing con-tact with a surface of the guiding chamber (26)during the translation of the stator ring (4); and- making the guiding means (25) contact the sur-face of the guiding chamber (26) at a zone ofthe surface of the guiding means (25) having acurvature with such a radius of curvature (R) thata homogeneous contact pressure distribution isensured as the operating conditions of the pump(1) and, consequently, the position of the statorring (4), vary.

10. The method as claimed in claim 9, for regulating thedisplacement of a pump for the lubrication oil for theengine (30) of a motor vehicle

11. A lubrication system for an engine (30) of a motorvehicle, comprising a pump (1) according to any ofclaims 1 to 8.

Patentansprüche

1. Rotationsverdrängerpumpe für Fluide, mit einemRotor (5), der zum exzentrischen Rotieren in einerKammer (40) angeordnet ist, die in einem Statorring(4) definiert ist, der in einem Sitz (3), der in einemPumpenkörper (2) ausgebildet und an Mittel (13, 14,15, 19) zum Verschieben eines solchen Rings beisich ändernden Betriebsbedingungen der Pumpe (1)relativ zu dem Rotor (5) angeschlossen ist, um diePumpenverdrängung zu ändern, wobei der Stator-ring (4) Führungsmittel (25) aufweist, die gleitend ineiner Führungskammer (26) angeordnet sind, die in

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dem Pumpenkörper (2) ausgebildet ist und mit einerDruckzone der Pumpe (1) oder mit Nutzvorrichtun-gen (100) eines gepumpten Fluids in Verbindungsteht, um das Fluid unter Druck aufzunehmen, da-durch gekennzeichnet, dass die Führungsmittel(25), während der Verschiebung des Statorrings (4),so angeordnet sind, dass sie durch das unter Druckstehende Fluid in dichtenden Kontakt mit einer Ober-fläche der Führungskammer (26) gedrückt werden,und in einer Kontaktzone (28) mit der Oberflächeeine Krümmung mit einem solchen Krümmungsra-dius (R) haben, dass eine homogene Kontaktdruck-verteilung gewährleistet ist, während die Betriebs-bedingungen der Pumpe (1) ändern und folglich diePosition des Statorrings (4) variiert.

2. Pumpe nach Anspruch 1, wobei die Führungsmittel(25) ein Paar von gegenüber liegend ausgerichtetenRippen (35), die sich im Wesentlichen tangential zudem Statorring (4) von einer Außenfläche des Sta-torrings (4) aus erstrecken und eine gemeinsameDruckfläche (27) definieren, auf die durch das FluidDruck ausgeübt wird, und ein Paar von Kontaktflä-chen (28), die jeweils die erwähnte Krümmung miteinem solchen Krümmungsradius (R) haben, dassdie homogene Kontaktdruckverteilung gewährleistetist.

3. Pumpe nach Anspruch 2, wobei die Rippen (25) ge-rundete freie Enden haben.

4. Pumpe nach einem der Ansprüche 1 bis 3, wobeidie Verschiebung des Statorrings (4) von einem ers-ten und einem zweiten Druckkopf (13, 14) gesteuertwird, die auf diametral gegenüberliegende Flächendes Rings drücken und dazu angeordnet sind, in ei-ner ersten bzw. einer zweiten Druckkammer (15, 16)jeweils verschoben zu werden, wobei die Druckkam-mern von der Führungskammer (26) getrennt sindund mit der Druckzone der Pumpe (1), oder bevor-zugt, mit den Nutzvorrichtungen (100) des gepump-ten Fluids durch ein Druckregelventil (19) oder direktin Verbindung stehen.

5. Pumpe nach Anspruch 4, wobei das Druckregelven-til (19) in die Pumpe (1) integriert ist.

6. Pumpe nach Anspruch 4 oder 5, wobei beide Druck-köpfe (13, 14) dazu angeordnet sind, eine Saugum-gebung (43) der Pumpe von einer Hochdruckumge-bung, in der die Führungsmittel (25) gleiten, zu tren-nen.

7. Pumpe nach einem der Ansprüche 1 bis 3, wobeidie Verschiebung des Statorrings (4) von einemelektrischen Motor gesteuert wird.

8. Pumpe nach einem der vorstehenden Ansprüche,

wobei die Pumpe (1) eine Pumpe für einen Schmier-mittelkreislauf (100) eines Motors eines Fahrzeugsist.

9. Verfahren zum Steuern der Verdrängung einer Ro-torverdrängerpumpe (1), mit den folgenden Schrit-ten:

- Verschieben eines Statorrrings (4), in dem sichder Rotor (5) exzentrisch dreht, relativ zu einemRotor (5) der Pumpe (1);- Führen der Verschiebung des Statorrings (4)mittels Führungsmitteln (25), die dazu angeord-net sind, innerhalb einer Führungskammer (26)zu gleiten, die in einem Pumpenkörper ausge-bildet ist und mit einer Druckzone der Pumpe(1) oder mit Nutzvorrichtungen (100) des ge-pumpten Fluids in Verbindung steht;

wobei das Verfahren dadurch gekennzeichnet ist,dass es zudem die folgenden Schritte aufweist:

- Veranlassen des gepumpten Fluids auf dieFührungsmittel (25) einzuwirken, um diese wäh-rend der Verschiebung des Statorrings (4) indichtendem Kontakt mit einer Oberfläche derFührungskammer (26) zu halten; und- Veranlassen der Führungsmittel (25) die Ober-fläche der Führungskammer (26) in einem Be-reich der Oberfläche der Führungsmittel (25) zukontaktieren, der eine Krümmung mit einem sol-chen Krümmungsradius (R) hat, dass eine ho-mogene Druckverteilung gewährleistet ist,wenn sich die Betriebsbedingungen der Pumpe(1) und folglich die Position des Statorrings (4)ändern.

10. Verfahren nach Anspruch 9 zum Steuern der Ver-drängung einer Pumpe für Schmieröl für den Motor(3) eines Fahrzeugs.

11. Schmiersystem für einen Motor (30) eines Fahr-zeugs mit einer Pumpe (1) nach einem der Ansprü-che 1 bis 8.

Revendications

1. Pompe volumétrique rotative destinée à des fluides,comportant un rotor (5) agencé pour tourner de façonexcentrée dans une chambre (40) définie à l’intérieurd’une bague de stator (4), laquelle est placée dansune embase (3) formée dans un corps de pompe (2)et est raccordée à des moyens (13, 14, 15, 19) pourtranslater une telle bague par rapport au rotor (5),lorsque les conditions de fonctionnement de la pom-pe (1) varient, en vue de modifier le débit volumétri-que de la pompe, dans laquelle la bague de stator

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(4) comporte des moyens de guidage (25) agencéspour coulisser dans une chambre de guidage (26)formée dans le corps de la pompe (2) et communi-quant avec une zone de pression de la pompe (1)ou avec des dispositifs d’utilisation (100) d’un fluidepompé, afin de recevoir, à partir d’elle, du fluide souspression, caractérisée en ce que les moyens deguidage (25), pendant la translation de la bague destator (4), sont agencés pour être poussés par lefluide sous pression en vue d’établir un contact étan-che avec une surface de la chambre de guidage (26)et, dans une zone (28) de contact avec cette surface,ils présentent une courbure dotée d’un rayon decourbure (R) tel qu’une distribution homogène de lapression de contact est assurée lorsque les condi-tions de fonctionnement de la pompe (1) et, en con-séquence, la position de la bague de stator (4), va-rient.

2. Pompe selon la revendication 1, dans laquelle lesmoyens de guidage (25) comprennent une paired’ailettes orientées dans des directions opposées(35) s’étendant essentiellement, de façon tangen-tielle à la bague de stator (4) à partir d’une surfaceextérieure de la bague de stator (4) et définissantune surface de poussée commune (27) qui est acti-vée par le fluide sous pression et une paire de zonesde contact (28) présentant, chacune, ladite courburedotée d’un rayon de courbure (R) tel que la distribu-tion homogène de la pression de contact est assu-rée.

3. Pompe selon la revendication 2, dans laquelle lesailettes (25) présentent des extrémités libres arron-dies.

4. Pompe selon l’une quelconque des revendications1 à 3, dans laquelle la translation de la bague derotor (4) est commandée par une première et uneseconde têtes de poussée (13, 14), lesquelles agis-sent sur des surfaces diamétralement opposées dela bague et sont agencées pour coulisser, respecti-vement, dans une première et dans une secondechambre de poussée (15 , 16), lesquelles chambressont distinctes de la chambre de guidage (26) etcommuniquent avec la zone de pression de la pom-pe (1) ou, de préférence, avec les dispositifs d’utili-sation (100) du fluide pompé, par l’intermédiaired’une vanne de régulation (19) ou directement, res-pectivement.

5. Pompe selon la revendication 4, dans laquelle lavanne de régulation (19) est intégrée dans la pompe(1).

6. Pompe selon la revendication 4 ou 5, dans laquelleles têtes de poussée (13, 14) sont disposées pourséparer un environnement d’aspiration (43) de la

pompe d’un environnement de pression élevée danslequel les moyens de guidage (25) coulissent.

7. Pompe selon l’une quelconque des revendications1 à 3, dans laquelle la translation de la bague destator (4) est commandée par un moteur électrique.

8. Pompe selon l’une quelconque des revendicationsprécédentes, dans laquelle la pompe (1) est unepompe destinée à un circuit de lubrification (100) dumoteur d’un véhicule à moteur.

9. Procédé de régulation du débit volumétrique d’unepompe volumétrique rotative (1) comportant les éta-pes comprenant le fait de :

- translater, par rapport à un rotor (5) de la pom-pe (1) une bague de stator (4) à l’intérieur delaquelle le rotor (5) tourne de façon excentrée ;- guider la translation de la bague de stator (4)par l’intermédiaire de moyens de guidage (25)agencés pour coulisser dans une chambre deguidage (26) formée dans un corps de pompe(2) et communiquant avec une zone de pressionde la pompe (1) ou avec des dispositifs d’utili-sation (100) du fluide pompé ;

le procédé étant caractérisé en ce qu’il comporte,de plus, les étapes comprenant de :

- laisser le fluide pompé agir sur les moyens deguidage (25) afin de les maintenir en contactétanche avec une surface de la chambre de gui-dage (26) pendant la translation de la bague destator (4) ; et- laisser les moyens de guidage (25) en contactavec la surface de la chambre de guidage (26)au niveau d’une zone de la surface des moyensde guidage (25) qui présente une courbure do-tée d’un rayon de courbure (R) tel qu’une distri-bution homogène de pression de contact est as-surée lorsque les conditions de fonctionnementde la pompe (1) et, en conséquence, la positionde la bague de stator (4), varient.

10. Procédé selon la revendication 9, permettant de ré-guler le débit volumétrique d’une pompe destinée àl’huile de lubrification pour le moteur (30) d’un véhi-cule à moteur.

11. Système de lubrification destiné à un moteur (30)d’un véhicule à moteur, comportant une pompe (1)selon l’une quelconque des revendications 1 à 8.

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the Europeanpatent document. Even though great care has been taken in compiling the references, errors or omissions cannot beexcluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• US 2004247643 A [0005] [0008]• US 2008038117 A [0005] [0008]

• WO 2005068838 A1 [0005] [0006]• EP 1600637 A [0005]