FR2583464A1 - MULTICELLULAR PALLET PUMP WITH HOOK-SHAPED PALLETS - Google Patents

Abstract

MULTICELLULAR VANE PUMP, IN PARTICULAR VACUUM PUMP, INCLUDING TWO OR MORE PALLETS MOVABLE IN SLOTS OF A ROTOR AS WELL AS DEVICES TO LIMIT THEIR RADIAL DISPLACEMENT. EACH PALLET 4, 5 INCLUDES A RIB 7 PARALLEL TO THE AXIS ON ONE OF ITS LATERAL SURFACES, WHICH SLIDES, THROUGH ITS AREA LOCATED RADIALLY ON THE EXTERIOR, ON AN OPPOSED RIB 26, RIB 7 AND THE OPPOSITE RIB 26 FORMING A CLOSED CHAMBER 10 WITH VARIABLE VOLUME WHICH, DURING A ROTATION OF THE ROTOR, COMMUNICATES WITH A SENSITIVELY CENTRAL PRESSURE FLUID FITTING.

Description

Multicellular vane pump with shaped pallets

of hooks.

  The invention relates to a multicellular vane pump, in particular to a vacuum pump, comprising two or more pallets displaceable in slots of a rotor as well as devices

  to limit the radial displacement of the pallets.

  In particular, in multicellular vane pumps which, for example in a motor vehicle, are coupled to the drive system so as to rotate constantly therewith and whose function is to maintain a hydraulic accumulator, for example a brake booster , constantly at a predetermined pressure or depression, multiple attempts have been made to interrupt or decrease pump flow when needed. The possibility of switching on and off the pump necessitates the implementation of considerable additional resources which increase, moreover,

  the fault sensitivity of the machine.

  In case of need, an attempt was made to neutralize the multicellular vane pump by pulling or rotating the pallets under conditions

  predetermined to remove them from the body wall.

  Thus, for example, German Patent Application 40949 discloses a rotary vacuum pump comprising a rotor rotating eccentrically in a bore of the body and at least one pallet provided with a device for holding it in a position excluding any action of the pump. This device consists of a mass which is coupled to each pallet and which, in the event of a high rotation speed, pulls the pallets to remove them.

  frontal surface of the inner wall of the body.

  German Patent Application No. 30 14 520 discloses a multicellular vane pump comprising pallets fixed on the periphery of the rotor and which, pivotable about their hinges placed on the surface of the rotor, are applied to the inner wall of the body under the effect of centrifugal forces or kinematic guidance. To pivot the pallets in a position where the discharge is interrupted, in the region of each of the pivotable pallets radially radially displaceable pins are provided which, at one end, engage a recess in the section of the pallet. circular end of the pallet and, by the other end, are applied on the side surface of a cone axially displaceable in a central bore of the rotary piston shaft. The pallets are

  returned or released by axial displacement.

  Both constructions are unsatisfactory.

  While in the former, the operation can not be modified from the outside and that, by design, it is effective only at low speeds of rotation, which limits very strongly its possibility of use, l the other is complicated, mechanically fragile and moreover usable exclusively with

  particular shape of the pivotable pallets.

  The object of the invention is therefore to equip the vane pumps with means enabling the vane to be placed in the operating position or in the idle position as required, possibly depending on a final pressure that can be determined by the outlet or at the inlet of the pump, and may be higher or lower than the atmospheric pressure. With a multicellular vane pump of the type described above, this result is achieved according to the invention in that each pallet, limitable in its displacement, comprises on a lateral surface, a rib parallel to the axis sliding in the slot corresponding, that the lateral surface provided with the rib slides by its radially outward zone on an opposite rib, that the rib and the opposite rib form a closed chamber which, during a complete rotation of the rotor, communicates with the less at times with a fluid connection under pressure and that this connection can be supplied with fluid under pressure. Preferably, the rib is disposed at the end of the pallet in the rotor and the end of the pallet is made hook-shaped. The pressurized fluid connection can be powered in particular depending on the depression or

the overpressure produced.

  In a particular embodiment, in particular in the form of a multicellular vacuum pump with vanes which is mounted in a motor vehicle and which is driven by the engine thereof, for example a gasoline engine or a diesel engine, the pressurized fluid connection, in the form of a channel, can be connected to the engine lubricating oil circuit to be fed with pressurized fluid. The opposite rib provided in the vane slot is preferably arranged parallel to

1 axis.

  In another embodiment, in the rotor are provided two pallets which are placed one above the other in a common slot and which both have a rib located in the region of their portion in the rotor . The ribs of the two pallets are turned towards each other, the rib of a pallet sliding on the face, which is turned towards it, the other pallet and the two ribs forming between them a pressure chamber (ci -after also called room hooks). The ribs of the two pallets may result from a hook-shaped design of the ends, located in the rotor, of the pallets, the heads of the hooks forming between them the pressure chamber whose length varies constantly between two limit values.

during rotation of the rotor.

  In a particular embodiment, the two vanes of the pump are also provided with hook heads at their ends located on the side of the inner wall of the body. Their radial extent is dimensioned so that their outer limits, the pallets being fully retracted, are in the enveloping surface of the rotor and that the head, located inside, of each pallet, is approximately applied to the inner surface of the rotor. the hook head, located on the outside, of the other pallet. With the pallets retracted, it may be advantageous to limit the supply of lubricating oil going inside the pump. For this purpose, it is provided according to the invention that the bores of lubricating oil generally provided in one or both side walls of the body, are practiced inside the zone covered by the rotor, so that they are constantly covered in position

return pallets.

  The chamber of the hooks can receive in different ways, the pressure causing the retraction of the pallets. A simple way is to connect the chamber of the hooks to the outlet of the pump, that is to say to the pressure chamber, or, for example in the case of installation of the pump in a motor vehicle and its training by the motor of the latter, to connect it to the lubricating oil circuit of the latter. In this case, in the connection is for example mounted a check valve acting as a pressure relief valve which is closed vis-à-vis the pressure chamber under the action of a pressure spring, preferably adjustable, and opens only when a determined pressure overcoming the force of the spring is reached in the pressure chamber. Other means are also possible, the control of movement of the pallets can for example also be carried out according to the speed

of rotation of the pump.

  The invention will be better understood using the

  description of embodiments taken as examples,

  but not limiting, and illustrated by the accompanying drawing, in which: Figure 1 shows a multicellular vane pump with control of the pallets by a two-way valve; Figures 2 to 5 show the relative position of the chamber of the hooks and the connection bore; Figure 6 shows the pump with vanes retracted into the rotor; Fig. 7 shows a pump with four individual pallets; FIG. 8 represents a pump with vanes of S or Z-shaped cross-section. Inside the body 1 of a pump, the rotor 3 is arranged eccentrically so as to be at a minimum.

  minimum distance from the inner wall 2 of the body.

  In the slot 6 of the rotor 3, the pallets 4 and 5 are mounted easily movable relative to each other and relative to the walls 14 of the slot. In

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  the embodiment shown, the pallets 4, 5, seen in cross section, in addition to the heads of

  inner hooks 7 essential for the invention -

  as will be explained later - also comprise hook heads 8 at their ends facing the inner wall 2 of the body. For the supply of pressurized fluid to the chamber or hooks 10, the axis of the rotor comprises a connecting bore 9 which opens into the slot 6 of the rotor. It can be placed either in the rotor shaft, when mounted on both sides, in the shaft end on the side opposite to the drive, or - in the case of cantilever mounting - in the front wall of the body 1 located on the opposite side to the drive. To ensure connection of the hook chamber 10 in any position of the rotor, the mouth of the bore 9, particularly if it is located in the opposite inner wall of the body, may preferably have a shaped enlargement 13 circle. As can be seen clearly in Figure 1, by the choice of appropriate dimensions, it is possible to feed the hooks chamber even at the extreme position shown, without the space between the end, being in the rotor, of the pallet 4, and the outer hook 8 of the pallet 5,

  is also connected to the drilling 9.

  In a particular embodiment, the side walls 14 of the slot 6, the sliding surfaces 11 and 12 of the pallets and the surfaces of the hook heads 7 and 8 in contact with the surfaces 11 and possibly also 14, can be provided with sheets extremely resistant to wear or a coating of metal, ceramic, mineral, glass or plastic, thereby significantly reducing wear. As a coating, it is possible, for example, to use

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  chromium, chrome alloys, hard enamel, glass, ceramics, plastics such as

  polytetrafluoroethylene and others.

  Figure 1 shows schematically a particular embodiment of the control of the movements of the pallets, the reference 19 designating a two-way valve which can be actuated by a control 22 membrane and push rod. From the distributor 19 start a pipe 24 going to the connection bore 9 and a second pipe 25 which goes to the lubricating oil connection 15, which is placed so as to be covered by the rotor 3. The inlet of the distributor is located at two feed ducts, namely a pressure connection 16, here marked with the sign (+) and a vacuum connection 17, marked with the sign (-). The illustrated dispenser position, in which the pressure connection is connected via line 24 to the connection bore 9 and the vacuum connection to the lubricating oil connection 15, is designated as the distributor position 1

  and causes the pallets 4, 5 to retract into the rotor.

  If the connection is established by the part 21 of the distributor (control position 2), there is a depression in the chamber of the hooks 10 and the pallets are released again, while the oil connector 15 is fed again in oil. The control of the two-way distributor 19 is effected by means of the pipe 23. The control pipe is connected to the inlet (not shown) of the multicellular vane pump. When the vacuum at the inlet falls below a predetermined value, the diaphragm (Figure 1) bends to the right and drives the push rod. The distributor then switches. Figures 2 to 5 reproduce different positions that can take the rotor during a rotation and by which we can see in which positions the chamber hooks, even in case of unfavorable dimensions, communicates with the connecting hole 9 or widening 13. It has however been found that the overlap which starts at a position of the rotor before that shown in FIG. 5 and which ends at a position after that represented in FIG. 2, is for example sufficient to guarantee the retraction of the pallets, The recovery zone increases as pallet retraction progresses. Figure 6 shows the situation with retracted pallets. In this position, the pallets 4 are firmly held as long as the link

with the pressure connection.

  FIG. 7 shows an embodiment of the multicellular vane pump according to the invention in which there are provided four individual pallets 43 guided in corresponding slots 42. The ribs 7, located respectively inside the slots 42, pallets 43 form, in combination with the opposite ribs 44 of the slots 42, the pressure chambers or chambers of the hooks 10; by the four positions represented by the pallets, we can clearly see their variation of length at

during a rotation of the rotor.

  The slots 42 in the rotor 3 end at a depth which must not be less than the radial length of the pallets; the two values are preferably substantially equal so that the outer limitations of the pallets 43, in the fully retracted state of the pallets, are in the enveloping surface of the rotor 3. In the rotor 3 is arranged a central bore 32 of which axis coincides preferably with the rotor axis and which serves to connect the

  slots 42 of the rotor by connection channels 33.

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  In the pump shown, the liquid supply of the pressure chambers or chambers of the hooks 10 is effected by a groove 31 provided, either in a front surface of the rotor 3, or in the front wall, which is close to it, of the body groove which is arranged concentrically on the surface of the rotor casing and in which the channel 9 of pressurized fluid opens at any place. The groove 31 is advantageously established so that its outer limitation, in the radial direction coincides substantially with the ridges, facing the axis of the rotor ribs 44 thereof. In this way, it is ensured that the pressure chambers 10 remain connected to the channel 9 even when they are at

their minimum length.

  We will now explain the operation of the multicellular vane pump using the embodiment shown, in which the reference 19 designates a multi-way distributor, the reference 34 a pump, for example the lubricating oil pump. a motor vehicle, and the reference 35, the tank or the oil sump. The multi-way manifold has two control sections (positions) 20 and 21. For its movement between positions 20 and 21, one side of the multi-way manifold is connected to the suction side of the pump via a control 22, of the pipe 37 and the connector 39, the other ceté is subjected to the action of a spring 36. At the control position 20, shown, the distributor 19, the central bore 32 is pressurized by the pump 34 via the pipe 40, while the pipe 41 connects the annular groove 31 to the tank 35 by the channel 9 of pressurized fluid. The pressure of the pump thus acts via the connection channels 33 on the base surfaces,

2583464

  radially on the inside, pallets 42, and pushing them outward, presses against the inner wall 2 of the body. When the pressure or the depression in the user, for example the brake booster 38, has reached its set point, the distributor 19 is switched to the position 21. Now, the central bore 32 is connected to the reservoir, while the groove 31 is supplied with pressure by the channel 9 of fluid under pressure. Therefore, the pressure chambers or chambers of the hooks 10 are pressurized and ensure the retraction of the pallets 42; the effect of the pump then ceases until the distributor 19 is at

switched again.

  FIG. 8 finally shows a multicellular vane pump according to the invention comprising pallets having a cross section which is modified with respect to the embodiment according to FIG. 1 and which here has an S-shape for the two pallets 4, 5 guided in their common slot 27. As can be seen in the drawing, the central zone of the slot is symmetrical with respect to an axial plane, while the enlarged parts opening out onto the periphery of the rotor of the slot 27, are offset laterally. one with respect to the other. The opposed ribs 26 which, in combination with the ribs or the hook heads 7, located inside the rotor, pallets 4, 5, form the pressure chambers or chambers of the hooks 10, constitute the transition between the symmetrical part and the offset part of the slot. When moving in the slot, the pallets 4, 5 slide one on the other by their surfaces 28, 29 facing one another, while the inner ribs or the heads of hooks 7 of the pallets 4 Slide on the side walls 30 of the slot. Due to the position and size of the chamber

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  In the case of fully-released pallets 5, the circular groove 31, connected to the pressurized fluid channel 9, has a very small external diameter and can therefore be replaced by the circular enlargement 13 of FIG. in this case nothing is changed to the described operation, the pallets 4, instead of the S-shape shown, may also have a Z-shaped cross-section. As already described for FIG. the pallet length measured in the diameter direction, the thickness of the hook head 8, measured in the same direction, is not

greater than the diameter of the rotor.

  The invention offers the possibility of triggering or triggering the operation of the pump according to the desired operating parameters, in that the distributor is controlled to pressurize the chamber of the hooks accordingly. of these operating parameters. If the pump is used for the production of a high pressure, a safety against inadmissible pressure increase can be ensured. If the pump is used to produce a vacuum, the pump can be stopped when a

  predetermined depression is reached.

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Claims (14)

  A multicellular vane pump, in particular a vacuum pump, comprising two or more pallets displaceable in slots of a rotor as well as devices for limiting the radial displacement of the pallets, characterized in that each of the pallets (4,5 ), which are limitable in their movement, comprises a rib (7) parallel to the axis on one of its lateral surfaces (11), that the lateral surface (11) provided with the rib (7) slides by its radially located zone outwardly on an opposite rib (26,44), that the rib (7) and the opposite rib (26,44) form a closed chamber (10) of variable volume which, during a rotation of the rotor, communicates at least at times with a connection (9) of fluid under substantially central pressure, and that the connection (9) can receive a fluid under pressure.   2. Pump according to claim 1, characterized in that the ribs (7) are respectively arranged on the end of the pallet   (4; 5) which is in the rotor (5).   3. Pump according to claim 1 or 2, characterized in that the connection (9) of pressurized fluid can be supplied with fluid under pressure as a function of the depression or the overpressure produced. 4. Pump according to any one of   claims 1 to 3, characterized in that it is   provided two or more, preferably four, slots (42) which respectively receive a pallet (45) and end in front of the central bore (32), that the various pallets (43) comprise ribs (7) at their ends located inside, and that the slots (42) have opposed ribs (44), the slots (42) with vanes being connected to the central bore (32) by connecting channels (33). 5. Pump according to any one of   claims 1 to 3, characterized in that in   the rotor (3) are installed two superposed pallets (4, 5) placed in a common slot (27), the ribs (7) respectively arranged on the end of the pallet which slides in the rotor, are arranged on the side located on the opposite side to the other pallet, and that the rotor slot near the center   of it carries the opposite rib (26). 6. Pump according to any one of   claims 1 to 3, characterized in that in   the rotor (3) are installed two superimposed pallets (4,5) placed in a common slot (6), that the two pallets (4,5) in the region of their part located in the rotor (5) respectively have a rib (7), and that the ribs (7) of the two vanes (4,5) are facing towards each other, the rib (7) of a pallet (4; 5) sliding on the side (11) turned towards it from the other pallet (5; 4) and that the two ribs (7) form between them   a pressure chamber or chamber of hooks (10).   7. Pump according to claim 6, characterized in that the ribs (7) of the two vanes (4, 5) are formed by the hook-shaped configuration of the ends of the vanes.   located in the rotor (3) and that the heads of the hooks-   (7) form between them a pressure chamber or chamber of hooks whose length is constantly changing between two limit values during the rotation of the rotor (3).   8. Pump according to claim 5 or 6, characterized in that the channel (9) of fluid under pressure at a front surface of the body (1) of the pump opens into a widening (13) and is in the alignment of the pressure chamber (10) between the hook heads (7) of the two pallets (4,5) of the pump.   9. Pump according to claim 8, characterized in that the bores (9) and the enlargement (s) (13) are arranged concentrically to the axis of the rotor.   10. Pump according to any one of   claims 5 to 9, characterized in that the   pallets (4,5) of the pump at their ends facing the inner wall (2) of the body are provided with hook heads (8), the two vanes (4,5) having a substantially shaped cross-section S or Z. 11. Pump according to any one of   Claims 5 to 9, characterized in that the   channel (9) of the pressurized fluid is provided as   axial drilling in the rotor shaft.   12. Pump according to any one of   preceding claims, characterized by the fact that   the rotor (3) has a central bore (32) and there are connections (33) with the slot (s) (42,27) of the rotor.   13. Pump according to any one of   preceding claims, characterized by the fact that   the chamber of the hooks (10) via a device (22) controlled by known means, can 2583464   alternatively receive pressurized oil for retracting the pallets (4,5; 43) and be connected to the tank (35) or a depression for their exit to the operating position.   14. Pump according to claim 19, characterized in that a pneumatically actuated switching valve (19) (control connection 23) (device 22), depending on the vacuum produced by the pump, connects the chamber of hooks. (10) alternately to the pressure connection (16) (position I (20)) of the dispenser for retracting the pallets (4,5; 43) and / or the reservoir (35) or the vacuum connection (17) (position II (21)) of the distributor to obtain the position of operation.