EP2795130B1 - Rotary positive displacement pump and method of regulating its displacement - Google Patents
Rotary positive displacement pump and method of regulating its displacement Download PDFInfo
- Publication number
- EP2795130B1 EP2795130B1 EP12815823.5A EP12815823A EP2795130B1 EP 2795130 B1 EP2795130 B1 EP 2795130B1 EP 12815823 A EP12815823 A EP 12815823A EP 2795130 B1 EP2795130 B1 EP 2795130B1
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- EP
- European Patent Office
- Prior art keywords
- pump
- stator ring
- chamber
- ring
- displacement
- Prior art date
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Classifications
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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
- F04C2/30—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
- F04C2/32—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having both the movement defined in groups F04C2/02 and relative reciprocation between co-operating members
- F04C2/321—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having both the movement defined in groups F04C2/02 and relative reciprocation between co-operating members with vanes hinged to the inner member and reciprocating with respect to the inner member
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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
- F04C14/00—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations
- F04C14/18—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber
- F04C14/22—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber by changing the eccentricity between cooperating members
- F04C14/223—Control of, monitoring of, or safety arrangements for, machines, pumps or pumping installations characterised by varying the volume of the working chamber by changing the eccentricity between cooperating members using a movable cam
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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
- F04C13/00—Adaptations of machines or pumps for special use, e.g. for extremely high pressures
- F04C13/001—Pumps for particular liquids
- F04C13/002—Pumps for particular liquids for homogeneous viscous liquids
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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
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0057—Driving elements, brakes, couplings, transmission specially adapted for machines or pumps
- F04C15/008—Prime movers
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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
- F04C15/00—Component parts, details or accessories of machines, pumps or pumping installations, not provided for in groups F04C2/00 - F04C14/00
- F04C15/0088—Lubrication
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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
- F04C2/30—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
- F04C2/34—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members
- F04C2/344—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member
- F04C2/3441—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member the inner and outer member being in contact along one line or continuous surface substantially parallel to the axis of rotation
- F04C2/3442—Rotary-piston machines or pumps having the characteristics covered by two or more groups F04C2/02, F04C2/08, F04C2/22, F04C2/24 or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having the movement defined in groups F04C2/08 or F04C2/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member the inner and outer member being in contact along one line or continuous surface substantially parallel to the axis of rotation the surfaces of the inner and outer member, forming the working space, being surfaces of revolution
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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
- F04C2250/00—Geometry
- F04C2250/30—Geometry of the stator
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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
- F04C2270/00—Control; Monitoring or safety arrangements
- F04C2270/18—Pressure
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Details And Applications Of Rotary Liquid Pumps (AREA)
- Reciprocating Pumps (AREA)
- Fuel-Injection Apparatus (AREA)
Description
- The present invention relates to variable displacement pumps, and more particularly it concerns a rotary positive displacement pump in which the displacement variation is obtained by means of the translation of a stator ring inside which the pump rotor eccentrically rotates.
- Preferably, but not exclusively, the present invention is employed in a pump for the lubrication oil of a motor vehicle engine.
- It is known that, in pumps for making lubricating oil under pressure circulate in motor vehicle engines, the pump capacity, and hence the oil delivery rate, depends on the rotation speed of the engine. Hence, the pumps are designed so as to provide a sufficient delivery rate at low speeds, in order to ensure lubrication also under such conditions. If the pump has fixed geometry, at high rotation speed the delivery rate exceeds the necessary rate, giving rise to a high power absorption, and consequently to higher fuel consumption, and to a greater stress of the components due to the high pressures generated in the circuit.
- In order to obviate this drawback, it is known to provide the pumps with systems allowing a delivery rate regulation at the different operating conditions of the vehicle, in particular through a displacement regulation. Different solutions are known to this aim, which are specific for the particular kind of pumping elements (external or internal gears, vanes...). Some general kinds of displacement regulation systems can however be identified, and one such system is based on the translation of an element (stator ring), which is arranged in a cavity of the pump body and surrounds the rotor with an eccentricity depending on the position taken by the same ring due to its translation.
- Examples of pumps of such kind are disclosed in
US 2004247643 ,US 2008038117 ,WO2005068838A1 andEP 1600637 . - In particular,
WO2005068838A1 discloses a positive displacement pump with a vane rotor, in which the stator ring is made to slide in response to the pressure difference in two chambers located at opposite sides of the stator ring and connected to the delivery side of the pump, one chamber directly and the other one through a control valve. The translation is guided by the same members on which the pressure controlling translation acts. - This prior art pump has a number of problems that mainly affect just the ring and concern in particular:
- feasibility: given the manner in which the stator ring of the prior art pump is kept in position against the action of the internal pressures generated by the pump operation and is guided during translation, particular mechanical tolerances and surface conditions are required in order to allow the proper displacement without sticking and without leaks;
- pressure stability: the pressure controlling the displacement of the stator ring is the pressure at the delivery side, and this entails that the system is considerably sensitive to the pressure fluctuations, typical of positive displacement pumps, present at the pump delivery side;
- wear: due to the pressures acting on the stator ring and the resulting sticking possibility, high wears occur between the contacting parts in the ring and the pump body.
- Pumps with a similar stator ring, originating the same problems, are disclosed in
US 2004247643 andUS 2008038117 - It is an object of the present invention to provide a pump in which the displacement is regulated by means of the translation of the stator ring, and a method of regulating the displacement of such a pump, which obviate the drawbacks of the prior art.
- According to the invention, this is obtained in that the stator ring includes guiding means arranged to slide in a guiding chamber formed in the pump body and preferably communicating with a pressure zone of the pump in order to receive fluid under pressure therefrom, and in that the guiding means, during the translation of the stator ring, are arranged to be pushed by the fluid under pressure into sealing contact with a surface of the guiding chamber and, in a zone of contact with such a surface, they have a curvature with such a radius that a homogeneous contact pressure distribution is ensured as the operating conditions of the pump and, consequently, the position of the stator ring, vary.
- Advantageously, the guiding means comprise a pair of fins, which extend substantially tangentially to the stator ring and in opposite directions from an outer surface of the ring, define a common push surface that is acted upon by the fluid under pressure and a pair of contact areas each having the radius of curvature ensuring the homogeneous contact pressure distribution, and have rounded free ends.
- In this manner, the possibility of sticking and the resulting wear are drastically reduced. Moreover, the need for sealing elements is eliminated.
- The translation may be mechanically controlled, by the action of the pressures in a circuit utilising the pumped fluid, or electronically controlled, by means of a motor controlled by an electronic control unit detecting the conditions of the same fluid in a utilisation circuit.
- The invention also implements a method of regulating the displacement of a rotary positive displacement pump by means of the translation of a stator ring inside which the pump rotor eccentrically rotates. According to such a method, such a translation is guided by guiding means arranged to slide in contact with a surface of a guiding chamber, formed in the pump body, due to the action of a pressurised fluid preferably coming from the delivery side of the pump, and the guiding means are made to contact the surface of the guiding chamber at a zone of the surface of the guiding means having a curvature with such a radius that a homogeneous contact pressure distribution is ensured as the operating conditions of the pump and, consequently, the position of the stator ring, vary.
- According to a further aspect of the invention, there is also provided a lubrication system for a motor vehicle engine, in which the adjustable displacement pump and the method of regulating the displacement set forth above are employed.
- Further features and advantages of the invention will become clearly apparent from the following description of preferred embodiments, given by way of non limiting examples with reference to the accompanying drawings, in which:
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Fig. 1 is an axial sectional view of a pump according to the invention; -
Fig. 2 is a front view of the pump, without the front cover, showing the stator ring in the maximum displacement position; -
Figs. 3 and 4 are enlarged views of details A and B ofFig. 2 ; -
Figs. 5 and6 are cross-sectional views of the pump, showing the stator ring in the maximum displacement and minimum displacement positions, respectively; -
Figs. 7 and 8 are enlarged views of details of the guiding fins of the stator ring; and -
Figs. 9 to 11 are diagrams of a lubrication circuit of a motor vehicle engine using the pump according to the invention, in different operating conditions. - Referring to
Figs. 1 to 6 ,reference numeral 1 generally denotes a rotary positive displacement pump with adjustable displacement, in particular a pump for the lubrication oil of a motor vehicle engine, of a kind comprising abody 2 in which achamber 3 housing astator ring 4 is formed.Ring 4 has aninternal cavity 40 in whichrotor 5 eccentrically rotates and it can be translated transversally to its axis in order to regulate the pump displacement.Rotor 5 is for instance a vane rotor,vanes 6 of which are radially slidable inradial slots 7, and it is driven by a suitably shaped shaft (not shown), which is inserted in acavity 10 of complementary shape. Acentring ring 11 is mounted at each of both axially opposite ends ofrotor 5 in order to keep the vanes in contact with the internal surface ofring 4 at low temperature and/or low speed. -
Chamber 3 is closed by afront cover 41 and arear cover 42.Channels rear cover 42. -
Suction channel 8 communicates, through achamber 45 inrear cover 42, withsuction chambers chamber 3 and ofinternal cavity 40 of thestator ring 4, respectively. Chambers 43, 44 also communicate with each other through achamber 46 formed infront cover 41. Such a supply on both sides of the rotor ofpump 1, which can also be referred to as "double supply", allows the pump to operate in conditions of absence of cavitation up to high rotation speeds. - Oil is sent in conventional manner from
suction chamber 44 to adelivery chamber 47 formed incavity 40 and communicating in turn withdelivery channel 9. -
Chamber 43 preferably allows collecting possible oil leaks insidepump 1, coming fromdelivery chamber 47 or generally from spaces under pressure, as it will be disclosed later on. -
Chamber 43, if it is located at a lower level thanchannel 8, also prevents the pump from emptying at the start from a stationary condition, after a long stop. - In the illustrated embodiment, the translation of
ring 4, which, by way of example, is supposed to take place horizontally, is controlled by the oil pressure in the engine lubrication circuit, as it will be disclosed later on. - The translation of
ring 4 is caused by a pair of substantiallycylindrical push heads ring 4. Advantageously, the contacting surfaces inheads ring 4 are flat surfaces, as shown inFig. 3 forhead 14. A flat contact surface does not demand special workings. Aprojection 12 in the wall ofchamber 3 acts as a stop for the maximum displacement stroke and it is arranged to maintain, in such a condition, a certain clearance betweenring 4 androtor 5, as it is better visible inFig. 4 . The position taken byring 4 in the condition of maximum displacement of the pump is also the reference position for mounting the ring intoseat 3. -
Heads body 2 so as to be slidable inrespective chambers plugs - The
first push head 13 is also biased by aspring 20 that is preloaded so thathead 13 keepsring 4 in a position of maximum displacement of the pump (Figs. 2 ,5 ) under low oil pressure conditions, in particular at the motor start. The flat surfaces ofhead 13 andring 4 in their contacting zones allow a homogeneous distribution of the force generated byspring 20 onring 4. - The
second head 14 is actuated to displacering 4 from the maximum displacement position towards the minimum displacement position when oil pressure inchamber 16 exceeds the preload ofspring 20, and it is pushed backwards byring 4 when the latter moves back to the maximum displacement position as oil pressure inchamber 16 decreases. Thanks to aspacer 21, which may also be integrally formed withhead 14, the latter is always kept in contact withring 4 and does not adhere to plug 18. -
Regulation valve 19 may be made to slide parallel to the displacement direction ofring 4, in order to manage the regulation pressures, thanks to a pair ofpush surfaces spring 24 tends to maintainvalve 19 in the position required inorder ring 4 remains in the maximum displacement position. Valve 19 may be integrated intopump body 2, in aseat 22 closed by aplug 23, as shown inFigs. 5 ,6 , or in the engine block, depending on the particular 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. - The connections of
chambers regulation valve 19 to the lubrication circuit will be disclosed later on. -
Ring 4 is so shaped as to have a guiding member, advantageously consisting of a pair offins 25 formed for instance in the top portion ofring 4. The fins extend substantially tangentially to the ring in opposite directions and they are housed in a guidingchamber 26 formed inbody 2 and communicating withdelivery channel 9. During the translation ofring 4,fins 25 slide in contact with the walls ofchamber 2 and the contact is ensured by the pressure of oil picked up fromdelivery channel 9 and acting on top faces 27 offins 25, defining a common push surface. The communication betweendelivery channel 9 andchamber 26 is obtained through a duct (not visible in the drawing) formed by means of a suitable working ofrear cover 41 and/orbody 2. - The shape of contact area 29 between each
fin 25 andbody 2 is such as to counterbalance the pressure forces generated inside the pump during operation and to maintain the contact withbody 2 in a limited area in any operating condition. In this manner, there is no need for sealing elements. In particular, as shown inFig. 7 ,fins 25contact body 2 according to a curved surface having a curvature with relatively wide radius R designed so as: - to keep the contact pressure within acceptable limits (cylinder-to-plane contact) without giving rise to upsetting of the material in the region underneath;
- to ensure a homogeneous contact pressure distribution as the operating conditions vary, notwithstanding
fins 25, as the pressure applied thereto increases, bend with a consequent displacement of the contact points. - Moreover, the free ends of
fins 25 have a rounded shape, designed so as to avoid that, due to the forces exerted by the moving fins or by internal overpressures (which could bring the fins in contact with the upper surface ofchamber 26,Fig. 8 ),ring 4 is blocked in case of an unbalance due to an overpressure surge within the pump. - Referring to
Figs. 9 to 11 ,lubrication circuit 100 of amotor vehicle engine 30 usingpump 1 is shown.Reference numerals delivery channels 8 and 9 (Fig. 1 ), through ducts also denoted byreference numerals Reference numeral 33 denotes the outlet duct offilter 12, conveying oil toengine 30. These Figures show an embodiment in whichregulation valve 19 is external to pumpbody 2. Such an embodiment allows more clearly seeing the connections ofvalve 19 withlubrication circuit 100 and with the rest ofpump 1. - A
branch 9a ofdelivery channel 9 conveys oil intochamber 26 in order to pushfins 25 into contact with the base ofchamber 26. As stated before, such a branch actually is a duct formed internally of the pump body. Afirst branch 33a ofduct 33 forms a first regulation duct conveying pressurised oil tochamber 16. A second and athird branch second inlet valve 19. Oil fed to thefirst inlet 49a preferably acts on thefirst push surface 19a in order to control the possible displacement ofvalve 19, whereas oil fed to thesecond inlet 49b may be transferred either to asecond regulation duct 35, communicating withchamber 15, or to exhaust 37. Thesecond branch 33b conveys oil also to adistribution valve 36, for instance an electromagnetic valve. Depending on the position of this valve,oil leaving filter 32 may be conveyed, through aduct 34, to athird inlet 49c ofvalve 19, where oil acts on asecond push surface 19b, or oil present invalve 19 in correspondence ofinlet 49c may be sent back to oil sump 31 (duct 38). - In accordance with other embodiments, oil fed to the
first inlet 49a and to thethird inlet 49c may act in reversed manner, for instance so that thefirst inlet 49a and thethird inlet 49c act on thesecond push surface 19b and thefirst push surface 19a, respectively. - Thanks to the provision of
distribution valve 36 and by properly dimensioning push surfaces 19a and 19b, it is possible to obtain two or more different intervention points forregulation valve 19. - It is to be appreciated that, depending on the requirements of the pump users, the regulation pressures (
ducts delivery channel 9 instead of being taken fromoutlet duct 33 of the filter. Yet, the illustrated solution is the solution ensuring the greatest stability in the regulation pressure since, as known, due the nature of the positive displacement pumps, the delivery pressure has surges that are smoothed byfilter 32. On the contrary, it is preferable to directly take the pressure acting onfins 25 from the delivery side, in order to constantly ensure the contact between the fins and pumpbody 2, even if other embodiments are possible. - It is also to be appreciated that, if
valve 19 is located inpump body 2,ducts body 2 by means of a suitable working, in similar manner to what has been stated for the duct puttingdelivery channel 9 in communication withchamber 26. - The operation of
pump 1 is as follows. - When the motor is started, there is a low oil pressure at the delivery side and the pump is in the maximum displacement condition (
Fig. 9 ). Under such a condition, the preload ofspring 24 pushesvalve 19 wholly to the left, so that oil can pass frominlet 49b toduct 35 and hence intochamber 15. In opposition to the reaction produced by the pressure sent into that chamber, thefirst regulation duct 33a picks up pressuredownstream filter 32 and sends it tochamber 16. Due to a force balance in the direction in which push heads 13, 14 act,ring 4 is in contact with mechanical stop 12 (Figures 2 ,3 ). - During the operation of
pump 1, the pressure atoutlet 33 from filter 32 (and hence atinlet 49a of valve 19) increases and, once it has exceeded a given threshold, it overcomes the preload ofspring 24, thereby makingvalve 19 displace to the right. The displacement ofvalve 19 progressively closesinlet 49b and putschamber 15 in communication withexhaust 37. In this manner, the pressure inchamber 15 decreases and the pressure inchamber 16 can overcome the preload ofspring 21 and displacering 4 proportionally to the pressure drop inchamber 15. Of course, the displacement ofring 4 ends when the minimum displacement position is reached (Fig. 10 ). - As the pressure in
duct 33 decreases, it is possible to resume the maximum displacement position thanks to the displacement ofvalve 19 to the left caused byspring 24. By such a displacement, the communication betweeninlet 49b andregulation duct 35 is restored and the pressure always present inchamber 16 can no longer overcome the combined action of the pressure in chamber 15 (which pressure is being progressively restored) and ofspring 21. - If an intervention of
valve 19 at a pressure level different from the high pressure level described above is desired,electromagnetic valve 36 will be actuated so as to apply the pressure existing atoutlet 33 offilter 32 also toinlet 49c of valve 19 (Fig. 11 ). The push is now exerted on bothpush surfaces spring 20 can be overcome by a pressure lower than the previous one. It is clear for the skilled in the art thatvalve 36 also allows obtaining also multiple actuation levels different from the high pressure level forregulation valve 19. - Thanks to the peculiar shape of
ring 4, the invention actually solves the problems mentioned above of the prior art. - Indeed, the mechanical and/or geometrical tolerances and the surface conditions suitable for ensuring the proper sliding of
ring 4 only concern the small contact zone betweenring 4 and body 2 (that is, betweenfins 25 and guide 26), whereas the whole remaining surface of the fins may remain raw. Also a special working of the ring surface zones in contact with push heads 13, 14 is not required. This allows reducing the manufacturing costs. - Moreover, the wide radius R in
zone 28 allows reducing the contact pressure and, as the pressure acting onring 4 varies during operation, it allows displacing the contact point while keeping the shape of the contact pressure distribution constant. This prevents sticking and wear of the parts in relative movement, always possible in the prior art. Also the rounded shapes of the ends offins 25 contribute to avoiding sticking during the normal sliding ofring 4 or during possible unbalances of same due to overpressure surges inside the pump. - On the other hand, the constant contact between
fins 25 andbody 2 eliminates the need for sealing elements in order to avoid excessive oil leaks, thereby contributing to the constructional simplicity and hence to the limitation of the manufacturing costs. The lack of sealing elements moreover assists in having a faster system response to the displacement variation signal. - It is clear that the above description has been given only by way of non-limiting example and that changes and modifications are possible without departing from the scope of the invention.
- For instance, even if in the illustrated embodiment the displacement of
ring 4 is mechanically controlled by the pressures in the lubrication circuit, an electronic control is also possible, through a small electric motor (brushless, three-phase synchronous or step-by-step motor) directly connected toring 4 through a lever system, a mechanical coupling or another linkage arranged to convert the rotary movement of the motor into a translatory movement. The motor will be electronically controlled by the electronic control unit of the motor vehicle, thereby ensuring a greater accuracy and a greater readiness in the intervention. The advantage of this solution is related to the possibility of having a continuous displacement variation in any condition of use, at any speed and temperature at infinite pressure levels. - Lastly, even if the invention has been disclosed in detail with reference to a pump for the lubrication oil of a motor vehicle engine, it may be applied to any positive displacement pump for conveying fluid from a first to a second working environment, in which a delivery rate reduction as the pump speed increases is convenient
Claims (11)
- A rotary positive displacement pump for fluids, comprising a rotor (5) arranged to eccentrically rotate in a chamber (40) defined within a stator ring (4), which is located in a seat (3) formed in a pump body (2) and is connected to means (13, 14, 15, 19) for translating such a ring relative to the rotor (5), as the operating conditions of the pump (1) vary, in order to change the pump displacement, wherein the stator ring (4) includes guiding means (25) arranged to slide in a guiding chamber (26) formed in the pump body (2) and communicating with a pressure zone of the pump (1) or with utilisation devices (100) of a pumped fluid, in order to receive fluid under pressure therefrom, characterised in that the guiding means (25), during the translation of the stator ring (4), are arranged to be pushed by the fluid under pressure into sealing contact with a surface of the guiding chamber (26) and, in a zone (28) of contact with such a surface, they have a curvature with such a radius of curvature (R) that a homogeneous contact pressure distribution is ensured as the operating conditions of the pump (1) and, consequently, the position of the stator ring (4), vary.
- The pump as claimed in claim 1, wherein the guiding means (25) comprise a pair of oppositely directed fins (35) extending substantially tangentially to the stator ring (4) from an outer surface of the stator ring (4) and defining a common push surface (27) that is acted upon by the fluid under pressure and a pair of contact areas (28) each having said curvature with such a radius of curvature (R) that the homogeneous contact pressure distribution is ensured.
- The pump as claimed in claim 2, wherein the fins (25) have rounded free ends.
- The pump as claimed in any of claims 1 to 3, wherein the translation of the stator ring (4) is controlled by a first and a second push head (13, 14), which act on diametrically opposite areas of the ring and are arranged to slide in a first and a second push chamber (15, 16), respectively, which chambers are distinct from the guiding chamber (26) and communicate with the pressure zone of the pump (1) or, preferably, with the utilisation devices (100) of the pumped fluid, through a regulation valve (19) or directly, respectively.
- The pump as claimed in claim 4, wherein the regulation valve (19) is integrated in the pump (1).
- The pump as claimed in claim 4 or 5, wherein the push heads (13, 14) are arranged to separate a suction environment (43) of the pump from a high pressure environment where the guiding means (25) slide.
- The pump as claimed in any of claims 1 to 3, wherein the translation of the stator ring (4) is controlled by an electric motor.
- The pump as claimed in any preceding claim, wherein the pump (1) is a pump for the lubrication circuit (100) of an engine of a motor vehicle.
- A method of regulating the displacement of a rotary positive displacement pump (1), comprising the steps 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 in a guiding chamber (26) formed in a pump body (2) and communicating with a pressure zone of the pump (1) or with utilisation devices (100) of the pumped fluid;the method being characterised in that it further comprises the steps of:- making the pumped fluid act upon the guiding means (25) in order to keep them in sealing contact with a surface of the guiding chamber (26) during the translation of the stator ring (4); and- making the guiding means (25) contact the surface of the guiding chamber (26) at a zone of the surface of the guiding means (25) having a curvature with such a radius of curvature (R) that a homogeneous contact pressure distribution is ensured as the operating conditions of the pump (1) and, consequently, the position of the stator ring (4), vary.
- The method as claimed in claim 9, for regulating the displacement of a pump for the lubrication oil for the engine (30) of a motor vehicle
- A lubrication system for an engine (30) of a motor vehicle, comprising a pump (1) according to any of claims 1 to 8.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT001188A ITTO20111188A1 (en) | 2011-12-22 | 2011-12-22 | VARIABLE DISPLACEMENT PUMP AND ADJUSTMENT METHOD OF ITS DISPLACEMENT |
PCT/IB2012/057167 WO2013093711A1 (en) | 2011-12-22 | 2012-12-11 | Rotary positive displacement pump and method of regulating its displacement |
Publications (2)
Publication Number | Publication Date |
---|---|
EP2795130A1 EP2795130A1 (en) | 2014-10-29 |
EP2795130B1 true EP2795130B1 (en) | 2016-03-16 |
Family
ID=45541021
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP12815823.5A Not-in-force EP2795130B1 (en) | 2011-12-22 | 2012-12-11 | Rotary positive displacement pump and method of regulating its displacement |
Country Status (4)
Country | Link |
---|---|
US (1) | US20150292502A1 (en) |
EP (1) | EP2795130B1 (en) |
IT (1) | ITTO20111188A1 (en) |
WO (1) | WO2013093711A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017084710A1 (en) * | 2015-11-19 | 2017-05-26 | Pierburg Pump Technology Gmbh | A variable displacement lubricant pump |
GB2552328A (en) * | 2016-07-18 | 2018-01-24 | Delphi Int Operations Luxembourg Sarl | Transfer pump |
CN110332446A (en) * | 2019-07-17 | 2019-10-15 | 湖南机油泵股份有限公司 | A kind of lubricating oil pump that can reduce feedback oil pressure fluctuation |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS53148703A (en) * | 1977-06-01 | 1978-12-25 | Jidosha Kiki Co Ltd | Variable volumetric pump |
WO2002001073A1 (en) * | 2000-06-29 | 2002-01-03 | Tesma International Inc. | Constant flow vane pump |
AUPR602401A0 (en) | 2001-06-29 | 2001-07-26 | Smart Drug Systems Inc | Sustained release delivery system |
ITBO20030528A1 (en) * | 2003-09-12 | 2005-03-13 | Pierburg Spa | PUMPING SYSTEM USING A PALETTE PUMP |
ITBO20040008A1 (en) * | 2004-01-09 | 2004-04-09 | Pierburg Spa | PUMPING PLANT |
DE102004026296A1 (en) | 2004-05-28 | 2005-12-15 | Daimlerchrysler Ag | oil pump |
-
2011
- 2011-12-22 IT IT001188A patent/ITTO20111188A1/en unknown
-
2012
- 2012-12-11 WO PCT/IB2012/057167 patent/WO2013093711A1/en active Application Filing
- 2012-12-11 EP EP12815823.5A patent/EP2795130B1/en not_active Not-in-force
- 2012-12-11 US US14/367,710 patent/US20150292502A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
ITTO20111188A1 (en) | 2013-06-23 |
US20150292502A1 (en) | 2015-10-15 |
WO2013093711A1 (en) | 2013-06-27 |
EP2795130A1 (en) | 2014-10-29 |
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