FR2884288A1 - Paint or lacquer metering pump, for lacquering body shell of motor vehicle, has packings mounted in case and between zone and region on extreme side of wheels, where packings are hermetically isolated in case by radial packing - Google Patents

Abstract

The pump has a case (2) with a sprocket wheel (9) in gear with a sprocket wheel (8) mounted in the case by a shaft (10). Packings (20-23) are associated to the respective wheels and are fixedly mounted in rotation in the case. The wheels have discharge zones (18, 19) formed of a set of teeth. The packings are between the zone and a region on an extreme side of the wheels and are hermetically isolated in the case by a radial packing (26). An inner cavity is between the packing (26) and the zone (18) and is dimensioned such that a flushing liquid travels the zone (18).

Description

DOSAGE PUMP OF LACQUER OR PAINT

  The present invention relates to a metering pump for lacquer or paint, comprising a housing in which there is a first gear and a second gear engaged with said first wheel, at least said first wheel being mounted in said housing by the intermediate of a tree; and a seal associated with the first gear wheel, each wheel having a discharge zone materialized by a toothing, said seal being interposed between said discharge zone and a region of the end face of the gear wheel.

  A gear pump with the characteristics mentioned in the introduction is known from patent application DE-A-19 56 528. In order to ensure the sealing of the region with respect to the discharge zone, of the pump not having to come into contact with the discharged substance, such as the shaft for example, an elastic seal is provided on the end faces of the gears, directly below the toothing. Holes are made either in the walls of the housing or in the end faces of the gear wheels to receive said liner.

  Lacquer or paint-based dosing pumps have proved their worth in lacquering or painting techniques. They constitute important auxiliary means for obtaining a deposit of lacquer or uniform paint and of high qualitative value.

  The need for a change of color is relatively frequent in many lacquering work, for example when lacquering motor vehicle bodies. In this case, it is essential that a color dosed by the pump is not soiled by a previously used color. For example, when a lacquer or white paint is deposited on a body, tiny residues of a lacquer or previously deposited red paint are, by themselves, extraordinarily troublesome.

  This is why the dosing pump is cleaned between two colors. For this purpose, a rinsing liquid is circulated through the pump, in a manner similar to that of the lacquering liquid or paint at an earlier stage. The pump is operated in such a way that the rinsing liquid can expel residual paint or lacquer still present in said pump. Nevertheless, this operation requires a relatively long time, as well as a relatively large amount of rinse liquid.

  From the state of the art, measures are known to minimize the region coming into contact with the lacquering or painting liquids; and to be able to more effectively remove color residues.

  According to the document WO-A1-01 / 86150, there is known a dosing pump in lacquer or painting the first toothed wheel is mounted unilaterally, in the housing, using a shaft. The second gear wheel is rotatably mounted in the housing, and passes through a wall that surrounds it. The shaft of the first wheel is engaged through a bearing whose radial seal against the housing is provided by means of an O-ring.

  DE-Al-198 49 200 discloses a gear pump equipped with gaskets, which gaskets are interposed between the housing wall and the end wall of said gears. Chambers, provided under the trims, can be pressurized. This pressure counteracts, from the other side of each lining, the pressure exerted by the liquid to be discharged; and thus prevents, in addition to the action of the gaskets, the penetration of the liquid in protected areas.

  From WO-A1-98 / 25029, there is known a unit unit motor-pump in which said pump is made as a gearwheel pump. To protect the drive shaft of the toothed wheel against the discharged liquid, there is provided in the end face of said wheel, an annular groove receiving a sealing means which seals said face. extreme of the wheel, vis-à-vis (the wall of the casing.) Said sealing means consists of an O-ring and an additional ring occupying a fixed position vis-à-vis said O-ring, and protecting the latter from frictional wear.

  EP-A2-1 164 293 discloses a rinsable gear pump. With additional channels, it is arranged that the rinsing agent travels through the interstices of the drive shaft surfaces over the entire width of said staves. Effective cleaning of the gear pump is thus ensured, so that no seal is required between the housing wall and the end face of said wheels.

  DE-C2-26 06 172 relates to a rotary piston machine for liquids. It has an external gear wheel engaged with an internal gear which has one more tooth. The seal, interposed between the housing wall and the external gear, is housed in an annular groove and consists of a resilient sealing ring, and a metal sealing ring. This metal ring remains fixed relative to said elastic ring, but however causes a low friction vis-à-vis the side wall.

  The present invention relates to an economical use of the metering pump of the aforementioned type.

  According to the invention, this object is achieved by the fact that the seal is hermetically sealed in the housing by means of a radial seal.

  Thus, one certainly prevents the lacquering liquid or paint to reach opposite and beyond the seal, which in turn would imply the risk of fouling parts in front, by themselves , be kept clean. This radial packing may simply be designed as an O-ring since it must provide only sealing between two static parts, ie the casing and the slip ring packing. Regions in which lacquering or painting liquid can creep, remain small because they are bounded by the seal. The further said liner is located far out, the larger is a region located at the end face of the gear wheel, and no longer fearing the solicitation by lacquering liquid or paint. Thus, the seal also has the effect of automatically maintaining lacquering or painting liquid away from the shaft, so that a lower complexity can be fundamentally deployed at the sealing stage of said shaft towards the shaft. outside. Of course, front surfaces still remain in the region of the toothing of the toothed wheel, that is to say the end faces of the individual teeth. Lacquering or painting liquid can certainly creep into these areas. This, however, is not critical since flushing liquid may similarly creep into these areas, more precisely in a manner comparable to the penetration of said lacquer or paint liquid. It is relatively simple to ensure, in a corresponding manner, that the previous color has been removed sufficiently after rinsing with the aid of the rinsing liquid. The smaller surface to be rinsed requires a smaller amount of rinse agent. This reduces costs. The rinsing time is shortened. The service life of the pump is extended accordingly. As a rule, said pump also has a longer life because reliably prevents lacquering or painting liquid from reaching the bearing areas through which the shaft is mounted in the housing. All this makes the operation of a pump thus produced extraordinarily economical.

  Preferably, the toothing has a root diameter, a radial distance, between said foot diameter and the seal, being smaller than a radial distance between said seal and the shaft. It is therefore possible to ensure, regardless of the diameter of the gear wheels used, that the region urged by lacquering or painting liquid, between the gear and the housing, can be kept small.

  The radial distance between the root diameter and the seal is preferably 1 mm. It is not imperative to have the gasket on the foot diameter, so that the risk of deterioration, caused by passing lanes, is kept low. Nevertheless, when a distance of 1 mm or less is provided, it is possible, on the one hand, a small risk of deterioration of the seal. It is further asserted that the fouled area does not become too large.

  Preferably, the seal is rotatably mounted in the housing. Said gasket therefore remains stationary. It is not driven by the rotating gear wheel. This keeps the wear low.

  The gear wheel preferably has, at least in the region of the seal, a wear-resistant surface. This wear-resistant surface can be deposited on the toothed wheel. It can also be embodied by a captive piece or insert cooperating with the seal. A wear-resistant surface increases longevity.

  Particular preference is then given to the fact that the wear resistant surface has a DLC coating. The abbreviation "DLC" then replaces the expression "Diamond Like Carbon", that is to say a carbon coating in the form of amorphous diamond. A coating of this kind has excellent sliding properties. It lends itself, to a particular extent, to a cooperation with the seal with low friction. It may also be provided to provide the entire sprocket with a DLC coating.

  The seal is preferably made in the form of a sliding ring seal. Slip ring liners can be made of wear and corrosion resistant materials and have good friction properties.

  Particular preference is then given to the fact that the sliding ring seal has, at least on its sealing surface, a metal, in particular a hard metal, a ceramic or a fluorinated resin. Such materials provide sufficient wear resistance and, in addition, provide sufficient sealing. Silicon carbide (SiC) is preferably employed.

  Preferably, the radial seal is disposed in the housing with a small dead space. In other words, the radial lining is arranged in such a way that only a small gap remains between the discharge zone and said radial lining which can be fouled by lacquering or painting liquid. The cleaning of this small dead space can then take place with corresponding simplicity.

  An advantage is also provided when there is an internal cavity between the radial seal and the discharge zone which can be traversed by a rinsing agent passing through said discharge zone. In the same way that lacquering or painting liquid can creep up to the radial seal, it is ensured that the rinsing liquid, before anyway be allowed to clean the discharge zone and the remaining areas from the dosing pump, can also insinuate itself to the radial seal in order to eliminate the lacquering or painting liquid.

  Preferably, the seal provides axial sealing on the gear wheel and, in the housing, a radial seal towards the discharge zone. The main characteristic then lies in the axial sealing with respect to the toothed wheel. This ensures that the end face of said gear wheel can, for the most part, be kept free of lacquering or painting liquid. The radial seal then prevents only a possible circumvention of said axial seal.

  It is also advantageous that the seal is preloaded, in the axial direction and in the radial direction, by means of a clamping means. The clamping means then makes it possible to adjust the sealing forces, which makes it possible reliably to prevent the penetration of lacquering or painting liquid into regions in which said lacquering or painting liquid is undesirable.

  Preferably, a connection for supplying a protective fluid emerges, in the radial direction, inside the seal. Such a protective fluid may take the form of a liquid, for example a protective oil. With the aid of the protective fluid, it is possible to develop, inside the seal, a pressure corresponding to the pressure of the lacquering or painting liquid outside said seal. This makes it possible to reliably prevent lacquering or painting liquid from flowing over and over the filling.

  Preferably, the two toothed wheels are mounted in the housing via a respective shaft. The wear of the second wheel is thereby kept modest. Admittedly, this translates into an additional region, that is, the bearing area of the shaft of the second wheel, which could be clogged in theory. However, this risk is eliminated again when a corresponding seal is also provided on the second wheel.

  Preferably, the gears are mounted axially on both sides in the housing. In other words, a shaft passes through each toothed wheel, or the gears have shaft ends on either side. This offers the advantage that virtually no bending force is applied to the gears mounting system. Trees located on either side can also be reliably sealed with the aforementioned lining.

  Preferably, the casing has a mounting surface in which or opens an inflow connection lacquer or paint and a lacquer flow connection or paint, and which is traversed by a drive shaft of the first gear, a power supply being applied against said surface. Maintenance or replacement is necessary from time to time also in the presence of reliable dosing pumps. However, if in practice connections are only provided in the mounting surface, the disassociation of the casing from the power supply implies, simultaneously, a break in the connection at the inflow and the flow, as well as the connection in the drive shaft (drive belt). Additional measures, to provide ducts or other connections, are practically superfluous. The dosing pump is therefore split into two modules, ie on the one hand the power supply unit and, on the other hand, the casing associated with the two gears which form the pump itself. This makes maintenance very easy.

  Preferably, the shaft of the first gear ends in the region of the mounting surface, and is provided with a coupling profile at that location. When the housing has to be replaced, the shaft does not protrude substantially beyond the mounting surface, or this projection is only very modest. The housing therefore remains very compact, which facilitates transport and reduces the risk of injury.

  Preferably, the power pack has an appendix that surrounds the drive shaft, and enters a recess in the mounting surface. This protrusion facilitates the mounting of said housing on said block. In addition, the connection zone between said block and said casing, which is the most strongly exposed to mechanical stress, is arranged in such a way that it can absorb said stress without any problem.

  The invention will now be described in more detail, by way of non-limiting example, with reference to the accompanying drawings, in which: FIG. 1 is a longitudinal section of a metering pump for lacquer or paint, partially disassembled; Figure 2 is a section along the line II-II of Figure 1; and Figure 3 shows, on an enlarged scale, a fragment of Figure 1.

  Figure 1 is a section of a pump 1 metering lacquer or paint, divided into two structural groups.

  The lacquer or paint dosing pump 1 has a casing 2 composed of an upper panel 3, a lower panel 4 and an intermediate panel 5.

  As evidenced by an observation of Figure 2, the intermediate panel 5 has two recesses 6, 7 approximately circular, partially overlapping. A first toothed wheel 8 is housed in the first recess 6 and a second toothed wheel 9, meshing with said wheel 8, is arranged in the second recess 7.

  Such a gear pump operates as follows: the first gear 8 is driven in a direction 11, via a shaft 10, and then drives the second gear 9 which rotates in a direction 12 with sense opposite rotation. The teeth of the two wheels 8, 9 interpenetrate in a zone 13 of engagement. A volume located between the teeth increases as it moves away from the area 13, so that a lacquering liquid or paint from an inflow connection 14 can enter the entredents. Said liquid located in the entredents is then driven by the teeth of the two wheels 6, 7, in the direction of movement. After a short period of rotation, the gaps are closed off by the intermediate panel 5. The liquid received in the entredents is then expelled from the latter, in the zone 13, and can be delivered via a flow connection. 15. The operation of such a gear pump is known by itself.

  Instead of a pump equipped with two wheels with external teeth, it is also possible to use, correspondingly, a gear pump comprising an external gear wheel and an internal gear wheel, knowing that said gear wheel outer toothing has a smaller diameter than the internal gear, and both wheels occupy mutually eccentric positions. A crescent type disc is interposed between the two wheels in an interstitial region. Such a crescent pump is also known by itself and can be used similarly in the present case.

  Each toothed wheel 8, 9 has teeth provided with ridges, and entredents provided with feet. On each wheel 8, 9, the ridges of the teeth are on a head diameter 16. The feet of the teeth are located on a foot diameter 17 on each wheel 8, 9. Said diameters 16 and 17 define, between them, a discharge zone 18, 19 (Figure 1).

  As shown in an observation of Figure 1, the two gears 8, 9 and the intermediate panel 5 have substantially the same thickness. The two wheels 8, 9 are thus applied against the upper panel 3 and against the lower panel 4, a small clearance being naturally reserved to allow a rotational movement of the two wheels 8, 9 in the housing 2.

  In order to prevent an incursion of paint or lacquering liquid into the region situated between the two toothed wheels 8, 9, and the panel 3 or 4, respectively upper or lower, each wheel 8, 9 is provided with seals 20 to 23. both on its upper and lower sides. All the liners 20 to 23 are, in principle, identical in construction. Accordingly, these liners 20 to 23 are discussed by considering respectively the example of the lining 21 (Figure 1) or the liner 20 (Figure 3).

  The seal 21 has an axial protuberance 24 not extending around the entire periphery of said lining 21. This protuberance 24 penetrates into a corresponding recess in the lower panel 4, and thus prevents rotation of the lining 21.

  An elastic member 25 constrains the seal 21, by a modest force, towards the toothed wheel 8. An O-ring (radial seal) 26 surrounds the seal 21 and prevents lacquering or painting liquid, from the discharge zone 18, to flow opposite the side of said lining 21 which is turned away from said wheel 8.

  The seal 21 cooperates with a captive piece 27 integrated in the end face of the toothed wheel 8. This piece 27 has an increased resistance to wear. It may, for example, be made of a ceramic or a metal, in particular a hard metal. It is also possible to provide this piece 27 with a DLC coating, that is to say a carbon coating in the form of amorphous diamond. A DLC coating can also be directly deposited on the end face of: the toothed wheel 8.

  As is apparent from FIG. 3, the radial sealing gasket 26 hermetically isolating the gasket 20 with respect to the casing 2 is mounted with a small dead space, that is to say it is retained on said crankcase with a dead space of modest magnitude. Said dead space is practically determined by the fact that the rib, retaining the radial seal 26, must not be too thin so as not to break. There remains between said radial gasket 26 and the discharge zone 18, an internal cavity 47 dimensioned so that a rinsing liquid, passing through said zone 18, can also traverse said cavity 47 so that lacquering liquid or paint, discharged until this moment, can be evacuated by said rinsing liquid.

  An observation of Figure 3 reveals that the elastic element (clamping means) 25 is, in this case, as a stack of springs. It exerts an axial tension on the seal 20, against the end face of the toothed wheel 8. Said element 25 can simultaneously be made such that it forces the seal 20 against the housing 2, outwards in the radial direction. This can be concretely obtained, in a simple manner, thanks to the fact that the element 25 has an outside diameter slightly larger than the inside diameter of the lining 20.

  The seal 21 is designed as a slip ring seal. Said lining 21 may also comprise a corresponding material resistant to wear, in particular a metal such as a hard metal, for example a ceramic or a fluororesin, preferably silicon carbide (SiC).

  As mentioned above, the first toothed wheel 8 is mounted in the housing 2 by a shaft 10. The second gear 9 is similarly mounted in said housing 2 via a shaft 28. The two shafts 10, 28 can rotate, the shaft 10 being locked in rotation with the first wheel 8 by means of a key 29.

  As shown in FIG. 1, the radial distance between the seals 20 to 23 and the delivery zone 18, 19 is substantially less than the radial distance between said seals 20 to 23 and the shafts 10. 28. More specifically, the distance refers to the side of the liners 20 to 23 which is turned towards the lacquering liquid or paint, that is to say, the point up to which said liquid can creep. As a result, it is clear that the regions on the end faces of the toothed wheels 8, 9, and may be fouled by lacquering liquid or paint, are relatively small. Correspondingly, only a small amount of rinsing liquid is also needed when dosing pump 1 is to be cleaned in the interval between two colors.

  The radial distance, between the seals 20 to 23 and the discharge areas 18, 19, must be at most 1 mm in all cases.

  In this way, on the one hand, the region that can be fouled by lacquering or painting liquid is maintained on the end faces of the gears 8, 9. On the other hand, it is scarcely to be feared that said gaskets 20 to 23 are, alternately, vis-à-vis a tooth and an entredent, and thus show wear.

  In order to clean the metering or paint dosing pump, a cleaning or rinsing liquid is admitted through the inflow connector 14 and discharged through the flow connection 15, in a manner similar to that of the lacquering liquid or paint. This rinsing liquid creeps into the same regions as those previously occupied by the lacquering liquid or paint, and carries with it stagnant color residues at these locations.

  There is further provided an insulating oil supply, which opens radially into the seals 20 to 23. Said oil supply has, for this purpose, a main channel 31 from which channels Bifurcation 32, 33 having, in turn, branches 34 to 37 which radially traverse the shafts 10, 28 and open, substantially in the region of the axial ends of the gears 8, 9, in a region respectively located between a shaft 10 , 28 and a wheel 8, 9.

  The shaft 10 is furthermore additionally equipped with a sealing system 38, whose main purpose is to prevent the isolation oil from coming out of the casing 2. The lacquering or painting liquid is already sufficiently prevented by the seals 20 to 23, leaving said housing 2.

  The housing 2 has a mounting surface 39 in lacquer or paint opens the inflow connection 14. As evidenced by an observation of Figure 2, said connector 14 is not arranged in the same plane as the axes 10, 28. The flow connector 15 also opens into the mounting surface, however with a shift perpendicular to the plane of the drawing in Fig. 1. The shaft 10 terminates substantially in the plane of the mounting surface 39 It has a coupling profile 40 at this end.

  The surface 39 is provided to allow mounting of a power supply unit 41 on the housing 2. The fixing of said block 41 to said housing 2 takes place by means of auxiliary means not shown in detail, such as bolts. The block 41 contains conduits 42 which lead respectively to the inflow connection 14 or to the flow connection 15, and can be opened or closed via a valve 43. It is furthermore provided in the block 41 , a drive shaft 44 connected to a drive motor not shown in detail. When said block 41 is mounted on said housing 2, the shaft 44 engages the shaft 10 so that the toothed wheel 8 can be driven. The power supply 41 has an appendix 45 surrounding the shaft

  44 and penetrating into a corresponding recess 46, made in the upper panel 3, when said block 41 is mounted on the housing 2. This allows, on the one hand, to obtain an orientation of the shaft 44 relative to the shaft 10. On the other hand, this has the effect of increasing the mechanical strength of the connection established between the housing 2 and the block 41.

  As a result, when it is desired to dismantle the lacquer or paint dosing pump 1 by separating the casing 2 from the power supply unit 41, it suffices to detach the mechanical connection introduced between said block 41 and said casing 2; after which the possibility is offered to dislocate, perpendicularly to the mounting surface 39, said casing 2 of said block 41 which, as a rule, is fixedly mounted. In this case, both the mechanical drive connection with the drive shaft 44 and the fluid communication with the conduits 42 are suppressed.

  The insulating oil supply 30 can of course also, in a manner not illustrated in detail, pass through the supply unit 41.

  It goes without saying that many modifications can be made to the dosing pump described and shown, without departing from the scope of the invention.

Claims (18)

-REVENDICATIONS-   A pump (1) for lacquering or painting, comprising a housing (2) in which there is a first toothed wheel (8) and a second toothed wheel (9) engaged with said first wheel, at least said first wheel ( 8) being mounted in said housing (2) via a shaft (10); and a seal (20-23) associated with the first toothed wheel, each wheel having a discharge zone (18, 19) materialized by a toothing, said seal being interposed between said discharge zone and a region of the face end of the toothed wheel, pump characterized in that the seal (20-23) is hermetically sealed in the housing (2) via a radial seal (26).   2. Pump according to claim 1, characterized in that the toothing has a foot diameter (17), a radial distance between said foot diameter (17) and the seal (20-23), being smaller than a radial distance between said lining (20-23) and the shaft (10, 28).   3. Pump according to claim 2, characterized in that the radial distance between the foot diameter (17) and the seal is <_ 1 mm.   4. Pump according to any one of claims 1 to 3, characterized in that the seal (20-23) is rotatably mounted in the housing (2).   5. Pump according to any one of claims 1 to 4, characterized in that the toothed wheel (8, 9) has, at least in the region of the seal (20-23), a surface resistant to wear.   6. Pump according to claim 5, characterized in that the wear resistant surface comprises a DLC coating.   7. Pump according to any one of claims 1 to 6, characterized in that the seal (20-23) is formed as a slip ring liner.   8. Pump according to claim 7, characterized in that the sliding ring seal has, at least on its sealing surface, a metal, in particular a hard metal, a ceramic or a fluororesin.   9. Pump according to claim 1, characterized in that the radial seal (26) is disposed in the housing (2) with a small dead space.   10. Pump according to claim 1 or 9, characterized in that an inner cavity (47), remaining between the radial seal (26) and the discharge zone (18, 19), can be traversed by a rinse agent passing through said discharge zone.   11. Pump according to any one of claims 1 to 10, characterized in that the seal (20-23) provides an axial seal on the toothed wheel (8, 9) and, in the housing (2) , a radial seal towards the discharge zone (18, 19).   Pump according to Claim 11, characterized in that the seal (20-23) is prestressed axially and radially by means of a clamping means ( 25).   13. Pump according to any one of claims 1 to 12, characterized in that a supply connection (30) of a protective fluid opens, in the radial direction, inside the packing of sealing (20-23).   Pump according to any one of claims 1 to 13, characterized in that the two toothed wheels (8, 9) are mounted in the housing (2) via a respective shaft (10, 28). .   15. Pump according to claim 14, characterized in that the toothed wheels (8, 9) are mounted axially on either side in the housing.   16. Pump according to any one of claims 1 to 15, characterized in that the housing (2) has a mounting surface (39) in which open a connection (14) influx of lacquer or paint and a connection (15) of lacquer flow or paint, and which is traversed by a shaft (44) for driving the first toothed wheel (8), a power supply unit (41) being applied against said surface (39).   Pump according to Claim 16, characterized in that the shaft (10) of the first toothed wheel (8) terminates in the region of the mounting surface (39) and is provided with a profile. coupling (40) at this location.   18. Pump according to claim 16 or 17, characterized in that the power supply unit (41) has an appendix (45) which surrounds the drive shaft (44), and enters a recess (46) made in the mounting surface (39).