EP2591210A2 - Pump with a vane rotor - Google Patents

Pump with a vane rotor

Info

Publication number
EP2591210A2
EP2591210A2 EP11748463.4A EP11748463A EP2591210A2 EP 2591210 A2 EP2591210 A2 EP 2591210A2 EP 11748463 A EP11748463 A EP 11748463A EP 2591210 A2 EP2591210 A2 EP 2591210A2
Authority
EP
European Patent Office
Prior art keywords
vane
rotor
vanes
slot
pump
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.)
Withdrawn
Application number
EP11748463.4A
Other languages
German (de)
French (fr)
Inventor
Volker Leifert
Luca Stagnoli
Antonio Crotti
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
VHIT SpA
Original Assignee
VHIT SpA
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by VHIT SpA filed Critical VHIT SpA
Publication of EP2591210A2 publication Critical patent/EP2591210A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
    • F04C18/30—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, or having the characteristics covered by one of these groups together with some other type of movement between co-operating members
    • F04C18/34—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, 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 group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members
    • F04C18/344—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, 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 group F04C18/08 or F04C18/22 and relative reciprocation between the co-operating members with vanes reciprocating with respect to the inner member
    • F04C18/3441—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, 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 group F04C18/08 or F04C18/22 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
    • F04C18/3442—Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups F04C18/02, F04C18/08, F04C18/22, F04C18/24, F04C18/48, 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 group F04C18/08 or F04C18/22 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 inlet and outlet opening
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
    • F01C21/00—Component parts, details or accessories not provided for in groups F01C1/00 - F01C20/00
    • F01C21/08—Rotary pistons
    • F01C21/0809—Construction of vanes or vane holders
    • F01C21/0818—Vane tracking; control therefor
    • F01C21/0854—Vane tracking; control therefor by fluid means
    • F01C21/0872—Vane tracking; control therefor by fluid means the fluid being other than the working fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
    • F01C21/00—Component parts, details or accessories not provided for in groups F01C1/00 - F01C20/00
    • F01C21/08—Rotary pistons
    • F01C21/0809—Construction of vanes or vane holders
    • F01C21/0881—Construction of vanes or vane holders the vanes consisting of two or more parts
    • 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
    • F04C27/00—Sealing arrangements in rotary-piston pumps specially adapted for elastic fluids
    • F04C27/001—Radial sealings for working fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01C—ROTARY-PISTON OR OSCILLATING-PISTON MACHINES OR ENGINES
    • F01C19/00—Sealing arrangements in rotary-piston machines or engines
    • F01C19/005—Structure and composition of sealing elements such as sealing strips, sealing rings and the like; Coating of these elements
    • 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
    • F04C2220/00—Application
    • F04C2220/10—Vacuum
    • 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
    • F04C2240/00—Components
    • F04C2240/20—Rotors

Definitions

  • the present invention relates to a pump with a vane rotor, in particular for use as a vacuum pump in motor vehicles, and to a pumping method by means of such a pump.
  • US 4,604,041 discloses a pump of this kind in which the rotor includes a slot mounting a pair of overlying vanes that, during rotation of the rotor, are slidable relative to each other and to the slot.
  • Each vane has a generally hook-like outline in cross- section and includes a shank portion and a head portion laterally projecting from the shank.
  • the shank has a width that is approximately half the slot width and it can overlie the shank of the other vane, whereas the head has a thickness substantially corresponding to the slot width and defines, with the end of the shank of the adjacent vane, a space into which oil is fed in order to push the vanes against the inner wall of the body.
  • the radial length of the vanes and the radius of the rotor are chosen so that, in certain angular positions of the rotor, both spaces are completely located within the slot and communicate with an oil feeding duct.
  • This prior art pump has a number of drawbacks.
  • a first drawback is that, notwithstanding the expansion-compression cycle of the spaces intended to contain the fluid requires in the whole a null average flow rate, an instant oil flow rate exceeding the actually available flow rate is necessary in order to create the proper contact between the vanes and the wall of the pump body.
  • a pump wherein the side surface of the rotor has, at the outlets of the slot, two recesses symmetrical with respect to the rotation axis of the rotor and having a circumferential extension greater than the width of the slot and substantially the same radial extension as the head portions of the vanes, said recesses moving opposite a duct feeding an incompressible fluid during a portion of the rotation path of the rotor, and wherein the head portion of each vane has substantially the same circumferential extension as said recesses, so that it can penetrate substantially without any clearance into a respective recess and seal it during said portion of the rotation path of the rotor.
  • the head portion of each vane defines inside the rotor, jointly with said recess and the facing end of the shank of the other vane, a closed space that is filled with the incompressible fluid, and such a closed space has a substantially constant volume as long as the head portions of the vanes are in contact with said wall, whereas, in case the head portion(s) of one or both vanes is (are) not in contact with said wall, the closed space undergoes a volume reduction that, because of the presence of the incompressible fluid, results in a push applied against the vanes.
  • the invention provides a pumping method comprising the steps of:
  • the closed space has a substantially constant volume as long as the head portions of the vanes are in contact with said wall, whereas, in case the head portion(s) of one or both vanes is (are) not in contact with said wall, the closed space undergoes a volume reduction that, because of the presence of the incompressible fluid, results in a push applied against the vanes.
  • - Fig. 1 is a sectional front view of a pump according to the invention
  • Fig. 2 is an enlarged view of a detail of Fig. 1;
  • Fig. 3 is a simplified sectional front view, showing the positions of maximum and minimum overall length of the vanes
  • Fig. 4 is an axial sectional view taken along line IV - IV of Fig. 3;
  • FIG. 5 to 7 show some alternative embodiments of the vanes.
  • the pump as a vacuum pump in a motor vehicle, for instance for operating servomechanisms such as a servo brake, a power steering system and so on.
  • a rotary vane pump 1 comprises a cylindrical body 2, having an axis Al and provided with an air suction duct 3 and an air exhaust duct 4, which are equipped with respective non-return valves 30, 40.
  • a rotor 5, also cylindrical, is eccentrically mounted within inner chamber 20 of body 2 and is made to rotate about axis A2, for instance by the cam shaft of the motor vehicle engine, through a driving joint 50 (Fig. 4).
  • Rotor 5 includes an axially and diametrically extending slot 6 in which a pair of overlying vanes 7A, 7B are slidably mounted for radial movement with respect to each other and to slot 6 during rotation of rotor 5, so as to remain in contact with the wall of chamber 20.
  • the height (axial extension) of vanes 6 is substantially the same as the axial extension of slot 6. Due to the eccentricity of rotor 5, during such rotation there will exist a position where the vanes have a maximum overall length, equal to the diameter of chamber 20 (vertical position, aligned with plane P passing through axes Al, A2, as shown in Fig. 3) and a position where the vanes have a minimum overall length (horizontal position, of which the trace is shown by dashed line m in Fig. 1).
  • Each vane 7A, 7B has a generally hook-like outline in cross-section, and includes a shank portion 8A, 8B and a head portion 9A, 9B laterally projecting from shank 8A, 8B in the rotation direction of rotor 5.
  • a direction is the counterclockwise direction, as shown by arrow F.
  • the vanes are mounted symmetrically and in opposite directions in slot 6, so that shanks 8 A, 8B overlie and the lower side 10A, 10B of a vane head faces the end of shank 8B, 8A of the other vane.
  • vanes 7A, 7B mutually exchange their positions every 180° of the rotor rotation, hereinafter suffixes A, B identifying the individual vanes and the respective parts will be omitted whenever they are not necessary for the understanding, and reference will be made to vanes 7 etc. For the same reason, suffixes A, B are not shown in Figs. 2, 4.
  • heads 9 laterally project from shanks 8 by a greater extent than the thickness of the same shanks, e.g. twice the shank thickness, which in turn is substantially half the width of slot 6, and hence they have an overall thickness greater than the width of slot 6.
  • two recesses 12A, 12B, symmetrical with respect to the rotation axis A2 of rotor 5, are formed on the side surface of rotor 5, at the outlets of slot 6.
  • Such recesses have circumferential extension substantially corresponding to the thickness of heads 9 so that the latter, when returning into rotor 5, can enter the respective recess 12 and seal it (apart from the constructive clearances).
  • heads 9 allows collecting the emulsion, particularly rich in oil, which is formed in the vicinity of the exhaust duct 4, and directing it into rotor 5. Moreover, the greater thickness of heads 9 with respect to the heads of the vanes of the above-mentioned document results in the centre of gravity B of the rotor-vane assembly being shifted towards the vane head, thereby increasing the contribution of the centrifugal force to the movement of vanes 7 out of slot 6, without need to insert weights into the vane heads.
  • each vane 7 and the extension of the arc of port 11 are such that head 9 of a vane enters the respective recess 12 and closes its outlet towards chamber 20 while the vane itself is displacing along port 11.
  • the head of one of the vanes in the position of maximum overall length, is completely retracted within recess 12 and its lower side 10 will be substantially in contact with the bottom of the recess.
  • the arc of port 11 extends over less than 180°, in the position of minimum overall length both heads 9A, 9B will be out of recesses 12A, 12B, which therefore will be in communication with chamber 20.
  • each vane while displacing along port 1 1 , forms with recess 12 and slot 6 a respective space 13 that is closed apart from oil supply port 11.
  • only one space 13 will always exist during a rotation cycle and it will be closed by either vane 7A or vane 7B, depending on which vane is passing opposite port 11.
  • the volume of space 13 is defined by the space left free between lower side 10A, 1 OB of a vane head and the end of shank 8B, 8 A of the other vane, and hence it depends on the vane kinematics.
  • the volume of space 13 is substantially constant, apart from an initial compression, since the volume decrease inside recess 12 caused by a vane 7 entering again rotor 5 is compensated by the space left free in slot 6 by shank 8 of the other vane, which is displacing radially outwards.
  • vanes 7 do not operate according to the desired kinematics (for instance, because one of them does not sufficiently move out of slot 6), the volume of space 13 tends to decrease. Consequently, as a reaction, a force is applied to vanes 7.
  • pump 1 as a vacuum pump is wholly similar to that of a conventional positive displacement pump with vane rotor and it does not require a detailed description.
  • novel features concern the manner in which vanes 7 are pushed against the wall of chamber 20 and such features have been thoroughly discussed above.
  • both heads never are simultaneously inside the respective space 13 and their main aim is to bring the air-oil emulsion into the respective space and to close said space during a portion of the rotation: the oil fed assists in pushing the vanes outwards under determined conditions, but it is not the exclusive push source.
  • Vanes 7 are advantageously made of aluminium, for instance by extrusion.
  • Head 9 will always be rounded in the area in contact with the wall of chamber 20 in order to keep friction limited: yet, apart from such a constraint, the head may have different profiles.
  • the upper contour of head 9 is concave in the portion protruding from the shank, so that a substantially bird-head shape is obtained.
  • the upper contour of head 9 may be convex over its whole extension, as shown for heads 90, 91 of vanes 70, 71 in Figs. 5, 6.
  • the radius of curvature may be constant or variable. It is to be appreciated that the front portion of head 90 in vane 70 is substantially flat.
  • vanes 7, 70, 71 are made of a single piece. It is also possible to have vanes made of two portions, as shown for vane 72 in Fig. 7.
  • a first portion 72' comprises the shank and the lower portion of the head, including side 10 intended to seal recess 12, and it is still made for instance of extruded aluminium.
  • a second portion 72" which comprises the surface in contact with the wall of chamber 20, is on the contrary made of an insert of steel or of polyamide charged with carbon fibres, in order to improve resistance to wear.
  • the two-portion solution can be adopted also for vanes 70, 71.

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

Abstract

A pump (1) has a rotor (5) eccentrically rotating within a pumping chamber (20) and a slot (6) housing a pair of vanes (7A, 7B; 70; 71; 72) with a hook-like outline, which are radially slidable with respect to each other and to the slot (6) during the rotation of the rotor (5), in order to adhere to the wall of the pumping chamber (20). The side surface of the rotor (5) has, at the outlets of the slot (6), two symmetrical recesses (12A, 12B) each of which can be closed by the head (9A, 9B; 90; 91) of a vane during a portion of the rotation path of the rotor (5), thereby building a closed space (13). A liquid contained in the closed space (13) applies a push to the vanes (7A, 7B; 70; 71; 72) in case of a reduction in the volume of the closed space (13) occurring if the vanes do not adhere to the wall of the pumping chamber (20).

Description

PUMP WITH A VANE ROTOR
The present invention relates to a pump with a vane rotor, in particular for use as a vacuum pump in motor vehicles, and to a pumping method by means of such a pump.
In several applications, including the one indicated above, use is made of positive displacement pumps with an eccentric rotor, within which a number of vanes are radially slidable and are pushed in contact with the inner surface of the stator. Due to the eccentricity of the rotor, during rotation of the latter a number of variable volume chambers are created, through which a fluid is mechanically transported from a suction port to an exhaust port.
For instance, US 4,604,041 discloses a pump of this kind in which the rotor includes a slot mounting a pair of overlying vanes that, during rotation of the rotor, are slidable relative to each other and to the slot. Each vane has a generally hook-like outline in cross- section and includes a shank portion and a head portion laterally projecting from the shank. The shank has a width that is approximately half the slot width and it can overlie the shank of the other vane, whereas the head has a thickness substantially corresponding to the slot width and defines, with the end of the shank of the adjacent vane, a space into which oil is fed in order to push the vanes against the inner wall of the body. The radial length of the vanes and the radius of the rotor are chosen so that, in certain angular positions of the rotor, both spaces are completely located within the slot and communicate with an oil feeding duct.
This prior art pump has a number of drawbacks.
A first drawback is that, notwithstanding the expansion-compression cycle of the spaces intended to contain the fluid requires in the whole a null average flow rate, an instant oil flow rate exceeding the actually available flow rate is necessary in order to create the proper contact between the vanes and the wall of the pump body.
Another drawback is that the centre of gravity of the vanes is very close to the rotation axis of the rotor and, consequently, in some angular positions, the centrifugal force being generated may be insufficient to generate the outward movement of the vanes, unless a weight is mounted in the vane head.
It is an object of the invention to provide a pump and a pumping method that obviate the drawbacks of the prior art.
According to a first aspect of the invention, there is provided a pump wherein the side surface of the rotor has, at the outlets of the slot, two recesses symmetrical with respect to the rotation axis of the rotor and having a circumferential extension greater than the width of the slot and substantially the same radial extension as the head portions of the vanes, said recesses moving opposite a duct feeding an incompressible fluid during a portion of the rotation path of the rotor, and wherein the head portion of each vane has substantially the same circumferential extension as said recesses, so that it can penetrate substantially without any clearance into a respective recess and seal it during said portion of the rotation path of the rotor.
During said portion of the rotation path, the head portion of each vane defines inside the rotor, jointly with said recess and the facing end of the shank of the other vane, a closed space that is filled with the incompressible fluid, and such a closed space has a substantially constant volume as long as the head portions of the vanes are in contact with said wall, whereas, in case the head portion(s) of one or both vanes is (are) not in contact with said wall, the closed space undergoes a volume reduction that, because of the presence of the incompressible fluid, results in a push applied against the vanes.
According to another aspect, the invention provides a pumping method comprising the steps of:
- forming on the side surface of the rotor, at the outlets of the slot, two recesses symmetrical with respect to the rotation axis of the rotor and having a circumferential extension greater than the width of the slot and substantially the same radial extension as the head portion of each vane;
- moving said recesses, during a portion of the rotation path of the rotor, opposite a duct feeding said substantially incompressible fluid;
- closing, during said portion of the rotation path of the rotor, one of said recesses by means of the head portion of one of the vanes, so as to define inside the rotor, jointly with said recess and the facing end of the shank portion of the other vane, a closed space which is filled with the incompressible fluid.
The closed space has a substantially constant volume as long as the head portions of the vanes are in contact with said wall, whereas, in case the head portion(s) of one or both vanes is (are) not in contact with said wall, the closed space undergoes a volume reduction that, because of the presence of the incompressible fluid, results in a push applied against the vanes.
The invention will now be described in greater detail with reference to the accompanying drawings, which show a preferred embodiment given by way of non- limiting example and in which: - Fig. 1 is a sectional front view of a pump according to the invention;
- Fig. 2 is an enlarged view of a detail of Fig. 1;
- Fig. 3 is a simplified sectional front view, showing the positions of maximum and minimum overall length of the vanes;
- Fig. 4 is an axial sectional view taken along line IV - IV of Fig. 3; and
- Figs. 5 to 7 show some alternative embodiments of the vanes.
For sake of clarity, where necessary, the following description will refer to the use of the pump as a vacuum pump in a motor vehicle, for instance for operating servomechanisms such as a servo brake, a power steering system and so on.
Referring to Figs. 1 to 4, a rotary vane pump 1 comprises a cylindrical body 2, having an axis Al and provided with an air suction duct 3 and an air exhaust duct 4, which are equipped with respective non-return valves 30, 40. A rotor 5, also cylindrical, is eccentrically mounted within inner chamber 20 of body 2 and is made to rotate about axis A2, for instance by the cam shaft of the motor vehicle engine, through a driving joint 50 (Fig. 4).
Rotor 5 includes an axially and diametrically extending slot 6 in which a pair of overlying vanes 7A, 7B are slidably mounted for radial movement with respect to each other and to slot 6 during rotation of rotor 5, so as to remain in contact with the wall of chamber 20. The height (axial extension) of vanes 6 is substantially the same as the axial extension of slot 6. Due to the eccentricity of rotor 5, during such rotation there will exist a position where the vanes have a maximum overall length, equal to the diameter of chamber 20 (vertical position, aligned with plane P passing through axes Al, A2, as shown in Fig. 3) and a position where the vanes have a minimum overall length (horizontal position, of which the trace is shown by dashed line m in Fig. 1).
Each vane 7A, 7B has a generally hook-like outline in cross-section, and includes a shank portion 8A, 8B and a head portion 9A, 9B laterally projecting from shank 8A, 8B in the rotation direction of rotor 5. Here, by way of example, such a direction is the counterclockwise direction, as shown by arrow F. The vanes are mounted symmetrically and in opposite directions in slot 6, so that shanks 8 A, 8B overlie and the lower side 10A, 10B of a vane head faces the end of shank 8B, 8A of the other vane.
Taking into account that vanes 7A, 7B mutually exchange their positions every 180° of the rotor rotation, hereinafter suffixes A, B identifying the individual vanes and the respective parts will be omitted whenever they are not necessary for the understanding, and reference will be made to vanes 7 etc. For the same reason, suffixes A, B are not shown in Figs. 2, 4.
Sliding of vanes 7 in slot 6 is essentially obtained due to the action of the centrifugal force and, in certain conditions, as it will be explained below, it is assisted by a liquid, in particular oil, which is fed under a slight pressure into chamber 20 and also serves for lubrication, heat removal and clearance sealing. Oil is fed through an axial port 1 1 and comes for instance from the engine through a channel 15 (fig. 4) formed in the wall of body 2 of pump 1. Port 1 1 has an arc-shaped outline in cross section and symmetrically extends at both sides of plane P passing through axes Al , A2. Preferably, port 1 1 has an extension somewhat smaller than 180°, for instance about 170°.
According to the invention, heads 9 laterally project from shanks 8 by a greater extent than the thickness of the same shanks, e.g. twice the shank thickness, which in turn is substantially half the width of slot 6, and hence they have an overall thickness greater than the width of slot 6. Moreover, two recesses 12A, 12B, symmetrical with respect to the rotation axis A2 of rotor 5, are formed on the side surface of rotor 5, at the outlets of slot 6. Such recesses have circumferential extension substantially corresponding to the thickness of heads 9 so that the latter, when returning into rotor 5, can enter the respective recess 12 and seal it (apart from the constructive clearances).
This shape of heads 9 allows collecting the emulsion, particularly rich in oil, which is formed in the vicinity of the exhaust duct 4, and directing it into rotor 5. Moreover, the greater thickness of heads 9 with respect to the heads of the vanes of the above-mentioned document results in the centre of gravity B of the rotor-vane assembly being shifted towards the vane head, thereby increasing the contribution of the centrifugal force to the movement of vanes 7 out of slot 6, without need to insert weights into the vane heads.
The diameter of rotor 5 , the length (radial extension) of each vane 7 and the extension of the arc of port 11 are such that head 9 of a vane enters the respective recess 12 and closes its outlet towards chamber 20 while the vane itself is displacing along port 11. Thus, as shown in Fig. 3, in the position of maximum overall length, the head of one of the vanes (vane 7B in the drawing) is completely retracted within recess 12 and its lower side 10 will be substantially in contact with the bottom of the recess. On the contrary, since the arc of port 11 extends over less than 180°, in the position of minimum overall length both heads 9A, 9B will be out of recesses 12A, 12B, which therefore will be in communication with chamber 20.
By such an arrangement, each vane, while displacing along port 1 1 , forms with recess 12 and slot 6 a respective space 13 that is closed apart from oil supply port 11. By the arrangement illustrated, only one space 13 will always exist during a rotation cycle and it will be closed by either vane 7A or vane 7B, depending on which vane is passing opposite port 11. The volume of space 13 is defined by the space left free between lower side 10A, 1 OB of a vane head and the end of shank 8B, 8 A of the other vane, and hence it depends on the vane kinematics.
More particularly, under proper operating conditions, with vanes 7 rotating steadily in contact with the wall of chamber 20, the volume of space 13 is substantially constant, apart from an initial compression, since the volume decrease inside recess 12 caused by a vane 7 entering again rotor 5 is compensated by the space left free in slot 6 by shank 8 of the other vane, which is displacing radially outwards.
If, on the contrary, vanes 7 do not operate according to the desired kinematics (for instance, because one of them does not sufficiently move out of slot 6), the volume of space 13 tends to decrease. Consequently, as a reaction, a force is applied to vanes 7.
This effect is optimised in that space 13 is filled with oil (which is substantially incompressible) fed into chamber 20 through port 1 1. The pressure of the air - oil emulsion present at the exhaust, increased by the oil entering vane 13, is then transmitted to the vanes and it generates a hydraulic force sufficient to make the vanes move out of the slot. In this manner, the system is made particularly sensitive and responsive to vane shifting, if any, away from the wall of chamber 20.
The general operation of pump 1 as a vacuum pump is wholly similar to that of a conventional positive displacement pump with vane rotor and it does not require a detailed description. The novel features concern the manner in which vanes 7 are pushed against the wall of chamber 20 and such features have been thoroughly discussed above.
It is to be appreciated that, even though US patent no. 4,604,041 discloses a vane rotor where the vanes have a widened head, that widening has a different aim from the present invention. In the prior art pump the vane heads are intended to define a minimum overall length for the coupled vanes and to form, jointly with the facing ends of the shanks and as long as both heads are inside the slot, chambers in which pressurised oil is fed in order to push the vanes outwards. In the present invention, both heads never are simultaneously inside the respective space 13 and their main aim is to bring the air-oil emulsion into the respective space and to close said space during a portion of the rotation: the oil fed assists in pushing the vanes outwards under determined conditions, but it is not the exclusive push source.
It is clear that the pump described above obviates the drawbacks of the prior art. The displacement of vanes 7 is not directly caused by oil fed through port 11 , and hence it does not depend on the oil flow rate. On the contrary, an oil- filled space exists and, in case of a reduction of the space volume due to an insufficient outward sliding of one of the vanes, the oil, thanks to its incompressibility, generates a reaction and applies to the vanes a hydraulic force assisting such a sliding. Moreover, the increased volume of heads 9 results in the centre of gravity being sufficiently spaced apart from the rotor axis so that the only action of the centrifugal force is normally sufficient to cause the vane displacement, even at low pump speed.
Vanes 7 are advantageously made of aluminium, for instance by extrusion. Head 9 will always be rounded in the area in contact with the wall of chamber 20 in order to keep friction limited: yet, apart from such a constraint, the head may have different profiles. For instance, in the vanes shown in Figs. 1 to 3, the upper contour of head 9 is concave in the portion protruding from the shank, so that a substantially bird-head shape is obtained. In the alternative, the upper contour of head 9 may be convex over its whole extension, as shown for heads 90, 91 of vanes 70, 71 in Figs. 5, 6. The radius of curvature may be constant or variable. It is to be appreciated that the front portion of head 90 in vane 70 is substantially flat.
In Figs. 1 to 6, vanes 7, 70, 71 are made of a single piece. It is also possible to have vanes made of two portions, as shown for vane 72 in Fig. 7. A first portion 72' comprises the shank and the lower portion of the head, including side 10 intended to seal recess 12, and it is still made for instance of extruded aluminium. A second portion 72", which comprises the surface in contact with the wall of chamber 20, is on the contrary made of an insert of steel or of polyamide charged with carbon fibres, in order to improve resistance to wear. Of course, the two-portion solution can be adopted also for vanes 70, 71.
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 as defined in the following claims.

Claims

Patent claims
1. A pump (1) with a vane rotor, including:
- a cylindrical pumping chamber (20) with an inlet (3) and an outlet (4) for a fluid to be pumped;
- a cylindrical rotor (5) eccentrically rotating within said chamber (20) and having a slot (6) axially and diametrically extending therethrough;
- a pair of vanes (7 A, 7B; 70; 71 ; 72) mounted in said slot (6) so as to be radially slidable with respect to each other and to the slot (6) during rotation of the rotor (5) in order to adhere to the wall of said chamber (20), each vane having, in cross-section, a substantially hook-like outline comprising a shank portion (8A, 8B), having a thickness substantially equal to half the width of the slot (6) and arranged in the slot (6) so as to overlie the shank portion of the other vane, and a head portion (9 A, 9B; 90; 91) laterally projecting from one end of said shank portion (8A, 8B) and having a lower side (10A, 10B) facing the other end of the shank (8B, 8A) of the other vane (7B, 7A); and
- a duct (11, 15) for feeding an incompressible fluid into said chamber (20);
wherein:
- the side surface of the rotor (5) has, at the outlets of the slot (6), two recesses (12A, 12B) symmetrical with respect to the rotation axis (A2) of the rotor (5) and having a circumferential extension greater than the width of the slot (6) and substantially the same radial extension as the head portions (9 A, 9B; 90; 91) of the vanes;
the pump being characterised in that:
- the head portion (9 A, 9B; 90; 91) of each vane (7 A, 7B; 70; 71, 72) has substantially the same circumferential extension as said recesses (12A, 12B), so that it can penetrate into a respective recess (12A, 12B) and create, in use, a closed space (13) with a substantially constant volume for said incompressible fluid, by cooperating with the end of the shank (8A, 8B) of the other vane and with the respective recess (12A, 12B).
2. The pump as claimed in claim 1, characterised in that said duct (11, 15) communicates with said chamber (20) through an arc-shaped port (11), the extension of which defines a portion of the rotation path arranged to create the closed space with constant volume.
3. The pump as claimed in claim 2, characterised in that the head portion (9 A, 9B; 90; 91) of a vane (7 A, 7B; 70; 71; 72) is arranged to collect and to introduce into the respective recess (12A, 12B), during an initial section of said portion of the rotation path, a mixture of incompressible fluid and pumped fluid.
4. The pump as claimed in claim 3, characterised in that, during said portion of the rotation path, the head portion (9 A, 9B; 90; 91) of each vane (7 A, 7B; 70; 71 ; 72) defines inside the rotor (5), jointly with said recess and the end of the shank of the other vane, a closed space (13) that is filled with said mixture of incompressible fluid and pumped fluid and that communicates only with said duct (11, 15) for feeding an incompressible fluid.
5. The pump as claimed in claim 4, characterised in that said closed space (13) has a substantially constant volume as long as the head portions of the vanes are in contact with said wall, and undergoes a volume reduction that, because of the presence of the incompressible fluid, results in a push against the vanes (7 A, 7B; 70; 71; 72), in case the head portion(s) (9A, 9B; 90; 91) of one or both vanes (7 A, 7B; 70; 71 ; 72) is (are) not in contact with said wall.
6. The pump as claimed in any one of preceding claims, characterised in that each vane (7 A, 7B; 70; 71) is made of a single piece.
7. The pump as claimed in any one of claims 1 to 5, characterised in that the vanes (72) include a first portion (72'), which comprises the shank and a lower portion of the head and is made of a first material, and a second portion (72"), which comprises the portion of the head intended to adhere to said wall, is inserted into said first portion (72') and is made of a second material with high resistance to wear.
8. The pump as claimed in any one of preceding claims, characterized in that it is a vacuum pump for automotive applications.
9. A pumping method by means of a pump (1) with an eccentric vane rotor (5), comprising the steps of:
- arranging within a cylindrical pumping chamber (20) with an inlet (3) and an outlet (4) for a fluid to be pumped, an eccentric rotor (5) having a slot (6) axially and diametrically extending therethrough and housing a pair of vanes (7A, 7B; 70; 71; 72) mounted overlying in said slot (6) so as to be radially slidable with respect to each other and to the slot (6) during rotation of the rotor (5) in order to adhere to the wall of said pumping chamber (20), each vane having, in cross-section, a substantially hooklike outline comprising a shank portion (8A, 8B), having a thickness substantially equal to half the width of the slot (6) and arranged in the slot (6) so as to overlie the shank portion of the other vane, and a head portion (9 A, 9B; 90; 91), laterally projecting from one end of said shank portion (8 A, 8B) and having a lower side (10A, 10B) facing the other end of the shank portion (8B, 8A) of the other vane (7B, 7A);
- feeding an incompressible fluid into said chamber (20);
- forming on the side surface of the rotor (5), at the outlets of the slot (6), two recesses (12A, 12B) symmetrical with respect to the rotation axis (A2) of the rotor (5) and having a circumferential extension greater than the width of the slot. (6) and substantially the same radial extension as the head portion (9 A, 9B; 90; 91) of each vane (7 A, 7B; 70; 71; 72);
- closing, during a portion of the rotation path of the rotor (5), one of said recesses (12A, 12B) by means of the head portion (9A, 9B; 90; 91) of one of the vanes (7A, 7B; 70;
71 ; 72), so as to define inside the rotor (5), jointly with said recess and with the end of the shank (8A, 8B) of the other vane, a closed space (13) with a substantially constant volume for said incompressible fluid.
10. The method as claimed in claim 9, characterised in that said closed space (13) has a substantially constant volume as long as the head portions (9 A, 9B; 90; 91) of the vanes are in contact with said wall, whereas, in case the head portion(s) (9 A, 9B; 90; 91) of one or both vanes (7 A, 7B; 70, 71 ;72) is (are) not in contact with said wall, said closed space tends to undergo a volume reduction that, because of the presence of the incompressible fluid, results in a radial outward push applied against one vane or both vanes (7 A, 7B; 70; 71; 72).
EP11748463.4A 2010-07-08 2011-07-07 Pump with a vane rotor Withdrawn EP2591210A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO2010A000590A IT1400885B1 (en) 2010-07-08 2010-07-08 VOLUMETRIC PUMP WITH PALETTE ROTOR.
PCT/IB2011/053027 WO2012004762A2 (en) 2010-07-08 2011-07-07 Pump with a vane rotor

Publications (1)

Publication Number Publication Date
EP2591210A2 true EP2591210A2 (en) 2013-05-15

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ID=43530567

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Application Number Title Priority Date Filing Date
EP11748463.4A Withdrawn EP2591210A2 (en) 2010-07-08 2011-07-07 Pump with a vane rotor

Country Status (3)

Country Link
EP (1) EP2591210A2 (en)
IT (1) IT1400885B1 (en)
WO (1) WO2012004762A2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110662903B (en) * 2017-05-25 2021-12-03 南洋理工大学 Rotating blade device

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4604041A (en) * 1984-04-09 1986-08-05 Barmag Barmer Maschinenfabrik Aktiengesellschaft Rotary vane pump
EP0205036B1 (en) * 1985-06-13 1989-05-31 B a r m a g AG Rotary vane pump
IT1190114B (en) * 1985-06-15 1988-02-10 Barmag Barmer Maschf FIN AND PUMP PUMP, WITH HOOK SHAPED FINS

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2012004762A2 *

Also Published As

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WO2012004762A2 (en) 2012-01-12
ITTO20100590A1 (en) 2012-01-09
WO2012004762A3 (en) 2013-04-04
IT1400885B1 (en) 2013-07-02

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