DE29823474U1 - Aerosol spray can with pressure relief valve - Google Patents

Description

•t ·

Aerosol spray can with pressure relief valve

The invention relates to an aerosol can with a spray valve with overpressure function located in its valve plate, which has a valve housing that is open towards the inside of the can and on its other side is sealed against the valve plate of the can housing and a hollow valve tappet that is slidably arranged in this, which protrudes through the valve plate of the can and in its depressed spray position creates a connection between the inside of the can and the environment and on which a valve body is provided that is axially movable against the force of a spring element pre-tensioned between itself and the valve tappet, which, in the closed rest position of the valve, pre-loads the valve body against the internal pressure of the can against a tight fit, whereby the valve tappet is pre-loaded by the spring element or another spring element against a fit on the valve housing or the valve plate.

The spray valves of aerosol cans must safely fulfil several functions. In addition to a secure sealing function when closed, which prevents the contents of the can from leaking out even after long periods of storage, there must be a sufficiently large passage in the spray position of the valve to enable the contents of the can to be sprayed properly. Furthermore, the spray valve must be able to reduce excess pressure that develops in the aerosol can, e.g. as a result of sunlight or decomposition of the contents of the can, as otherwise the aerosol can could explode.

DE-OS 2 314 912 describes a spray valve in which a spring element is located between the valve tappet and the valve body. A sealing element assigned to the valve tappet ensures that its inner cavity is sealed by being pressed against the valve body by the spring force. The valve tappet also has a second contact with a sealing ring supported on the valve plate. This means that the support of the valve tappet is overdetermined, so that no precisely determinable contact force is produced at the relevant sealing points. In unfavorable cases, this can lead to leaks. Another feature of the valve according to DE-OS 2 314 912 is that the valve body is supported not only by the coil spring, but also by an elastic ring on the valve plate. The elastic forces exerted by such a ring are very difficult to calculate, which is why the opening pressure of the valve can vary greatly in the event of excess pressure in the can, also due to additional manufacturing tolerances.

Another known valve for aerosol cans is described in G 92 17 926, which is, however, much more complex in construction because it works with separate elastic elements for returning the valve tappet to the rest position and for a separately designed pressure relief valve.

The G 91 11 351 also describes, among other things, a valve that has a pressure relief valve that is independent of the return spring. The transverse arrangement makes assembly difficult and, due to the lack of guidance of the valve body, it deviates in the axial direction when triggered. The can empties completely. In addition, a pressure relief valve with a predetermined breaking point is described that

·· 1

-3-

The disadvantage is that even with this solution, a brief overpressure, e.g. due to brief exposure to heat, leads to the can being completely emptied.

The object of the invention is to create an aerosol can with a spray valve with overpressure function, which has a simple structure and yet has a very precisely predeterminable opening pressure.

According to the invention, the object is achieved by an aerosol can of the type described at the outset, in which the passage to the inner cavity of the valve tappet consists of at least one radial passage opening in the region of its end protruding into the valve housing and in the region of the valve body a sealing element is provided which seals the valve housing against the valve tappet at normal can pressure, wherein in the rest position the radial passage opening is tightly closed by the sealing element.

The valve according to the invention consists of fewer components than the previously known designs. It has only a single elastic element, which serves to return the valve tappet to its rest position and to press the valve body against a contact with the valve housing, so that the inside of the can is sealed at normal pressure, but if the pressure rises above a certain permissible value, the applied pressure can move the valve body against the force of the elastic element and thus expose the passage opening. The valve also requires only a single sealing element to seal the valve housing against the tappet and at the same time close the passage opening when the valve is in the closed position.

Another advantage is that the opening pressure of the valve can be determined very precisely due to the characteristics of the spring element used, which are subject to only small tolerances, and does not change even under unfavorable conditions.

A further advantage of the valve according to the invention is that, in contrast to the known embodiments, the valve tappet is only pressed against one system by the elastic element, so that leaks cannot occur as a result of static overdetermination.

In a preferred embodiment of the invention, the interior of the valve housing or the interior of a sleeve arranged therein is designed as a cylindrical bushing in the area facing the valve plate, in which the valve body and the valve tappet provided with a piston-like shoulder run. A valve with such a design can be easily manufactured from a few parts, with the valve tappet and the valve body being guided in the same running surface.

The seal between the valve housing and the valve plate can be achieved by means of a sealing ring, which can be omitted if a valve plate coated with polypropylene (PP) is used. To improve the sealing effect between the valve housing and the valve plate, it can be advantageous if a ring bead with a triangular cross section is provided on the valve housing at the contact surface with the sealing ring or the PP layer.

An alternative according to the invention provides that in the area of the valve plate a radial passage opening to the cavity of the valve tappet is provided, which in the rest position is closed by a

housing is closed by a sealing ring provided, and the valve body is guided axially in the correspondingly expanded cavity of the valve tappet, whereby an opening in the cavity for reducing excess pressure in the rest position is closed by a sealing element provided at the axial end of the valve body under the axial preload force of the spring element. This solution also offers the advantage that the contact pressure of the sealing element on the sealing surface is precisely defined due to the precisely calculable spring force, so that a precise opening pressure can be determined. The valve body is also precisely guided in the valve tappet, so that even if the pressure only increases for a short time, the excess pressure opening can be closed again with the help of the spring element. The can can continue to be used.

Although this design requires an additional spring element, thanks to the separate design it is possible to reduce the pressure force required to reach the spray position on the valve tappet.

In a preferred development of this embodiment, it is provided that the valve tappet consists essentially of two parts, whereby the part facing the interior of the can is cup-shaped, has the overpressure opening on its underside, is fixedly arranged on the upper part of the valve tappet and accommodates the valve body, the sealing ring and the spring element between itself and the upper part.

The two-part valve tappet enables easy assembly of the valve body, which is inserted into the cup-shaped interior of the lower part before the two parts of the valve tappet are joined together.

According to a further embodiment of the invention, a stop is provided on the valve housing to limit the displacement path of the valve tappet in the spray position, which stop can, for example, be conical.

The limit stop prevents excessive compression of the valve tappet, which could lead to an inadmissible load on the sealing element on the valve body due to the spring force increasing with the compression path.

To improve the sealing effect between the valve body and the valve housing, an advantageous development of the invention provides for an annular bead to be formed in the contact area of the sealing element of the valve body on the valve housing. An annular bead with a triangular cross-section has proven to be particularly advantageous, as it ensures a particularly good seal between the valve body and the valve housing.

For manufacturing reasons, it is advantageous to provide cams pointing radially inwards at the upper end of the cylindrical liner. This makes it possible to completely prefabricate the valve before it is inserted into the valve plate. The cams prevent the spring element from forcing the valve tappet out of the liner.

In a further preferred embodiment of the invention, grooves are provided on the contact surface of the piston shoulder, which in the rest position rests against the sealing ring or the coated valve plate, the outer flanks of the piston shoulder and/or flanks of the valve body. This ensures that in the event of a high pressure increase inside the can, not only the normal spray passage is available for pressure relief, but

Aerosol can also escape via the outside of the valve tappet and the valve body. The functional reliability of the valve is also improved, as the valve tappet and the valve body remain more mobile in the cylindrical liner, even if contaminants, e.g. aerosol quantities escaping as a result of a brief overpressure, accumulate in the liner.

In the following, embodiments of the invention are discussed in more detail with reference to the accompanying drawings. They show:

Fig. 1 shows a cross-section through a valve of an aerosol spray can in the rest position;

Fig. 2 the valve according to Fig. 1 in spray position;

Fig. 3 the valve according to Fig. 1 in a position for reducing excess pressure;

Fig. 4 shows a cross section of another embodiment of a valve in the filling position;

Fig. 5 shows a cross section of another embodiment of a valve in a position for reducing excess pressure;

Fig. 6 a cross-section of yet another embodiment of a valve in the rest position and

-8th-

Fig. 7 shows a detailed cross-section of another embodiment of a valve in the filling position.

Fig. 1 shows the cross section of a valve 10 which is located in a valve plate 12 of an aerosol spray can (not shown in detail). The valve plate 12 is connected in a known manner at its edge to the cylindrical can wall in a sealing manner.

The valve 10 has a substantially cylindrical valve housing 14, inside which a cylindrical raceway 16 is provided that is open towards the valve plate 12. Between an upper end face 18 of the valve housing and the valve plate 12, a sealing ring 20 is provided that seals the valve plate 12 against the valve housing 14. In the area of its end face 18, the valve housing 14 has a ring-shaped, thickened outer wall 22 that is enclosed by the sheet metal of the valve plate 12 in such a way that the valve housing 14 sits firmly in it.

In the cylindrical track 16 of the valve housing 14, a valve tappet 24 is guided axially displaceably via a piston-like shoulder 26. The valve tappet 24, which is hollow on the inside, has a tubular rear end 28, which protrudes from the can through an opening 30 in the valve plate 12. A spray valve (not shown) can be attached to the tubular end 28 of the valve tappet 24, with the aid of which the aerosol flowing through the valve tappet 24 can be sprayed in the desired manner.

-9-

The tubular end 32 of the valve tappet 24 located inside the can is axially closed, but has at least one radial passage opening 36 in the area of the bottom of the inner cavity 34.

A valve body 38 is also movably guided in the cylindrical track 16 and sits on the tubular end 32 of the valve tappet 24. Between the piston-like shoulder 26 of the valve tappet 24 and the valve body 38, a coil spring 40 is provided which has a certain preload and therefore strives to force the piston-like shoulder 26 and the valve body 38 apart. A sealing element is attached to the underside of the valve body 38, which rests under the load of the coil spring 40 on a radially inwardly projecting shoulder 44 in the valve housing 14. In the left half of the figures, an embodiment is shown which differs from the right half of the figures, in which the shoulder 44 has an annular bead 46 with a triangular cross-section on its side facing the sealing element 42. This ensures a particularly good seal between the valve body 38 and the valve housing 14.

The sealing element 42 has such a small inner diameter that it also forms an effective seal between the valve body 38 and the lower end 32 of the valve tappet 24. In the rest position of the valve tappet 24, the radial passage openings 36 are exactly at the height of the sealing element 42, so that the valve is closed. Below the shoulder 44, the valve housing 14 tapers towards the bottom of the can to a tubular extension 48. A riser pipe 50 is placed on the extension 48, which reaches to the bottom of the aerosol spray can. To prevent the riser pipe 50 from slipping, the extension has

• ar

-10-

set 48 has a triangular bead 52. In the transition area from the tubular extension 48 to the shoulder 44, the valve housing 14 has a conical stop 54, against which the lower end of the valve tappet 24, which is also conical, rests when it is moved to its maximum. In order to ensure that the aerosol can pass through properly in this position, radial grooves 56 are provided in the lower end of the valve tappet 24.

The valve housing 14 is designed in such a way that the sealing element 42 and thus the valve body 38 is always exposed to the internal pressure of the can over a certain area.

In the rest position shown in Fig. 1, the valve is closed. The helical spring 40 presses the piston-like shoulder 26 of the valve tappet 24 against the sealing ring 20 and the valve body 38 with its sealing element 42 against the shoulder 44 or the annular bead 46. The valve tappet 24 and the sealing element 42 are in a precisely defined position relative to one another, in which the radial passage opening 36 is closed by the sealing element 42 which sits radially sealingly on the inner end 32 of the valve tappet 24.

In the spray position of the valve shown in Fig. 2, the valve tappet 24 is displaced towards the inside of the can. Since the valve body 38 with its sealing element 42 is axially fixed to the shoulder 44, the radial passage opening 36 is displaced relative to the sealing element 42 under increasing tension of the coil spring 40. From a certain point, the passage opening 36 is connected to the inside of the can via the tubular extension 48 and the riser pipe 50, so that aerosol can reach the spray head through the inner cavity 34 of the valve tappet 24.

As soon as no more pressure is exerted on the spray head, the coil spring 40 presses the valve tappet 24 back into its rest position, in which the sealing element closes the radial passage openings 36 again.

In Fig. 3, the valve 10 is in a position in which excess pressure in the aerosol can, for example due to overheating, is released. As already mentioned, the internal pressure of the can is applied to the sealing element 42. If it exceeds a certain level, the valve body 38 moves against the pressure of the coil spring 40. The valve tappet 24 does not change its position, since the piston-like shoulder 26 is axially fixed to the sealing ring 20. As a result, there is again a relative movement between the sealing element 42 and the radial passage opening 36, which, at a sufficiently high pressure, enables the aerosol to escape through the inner cavity 34 of the valve tappet 24. As soon as the pressure inside the can has returned to a normal level, the coil spring 40 presses the valve body 38 with the sealing element 42 against the shoulder 44 again, so that the passage opening 36 is closed again. In contrast to designs of valves with predetermined breaking points, the aerosol spray can is only emptied until the normal pressure is restored.

Another possible embodiment of the valve is shown in the right-hand halves of the figures. In this case, the piston shoulder 26 has radial grooves 58 on its side facing the sealing ring 20 and axial grooves on its circumferential surface (not shown) and the valve body 38 is also provided with axial grooves (not shown) on its outer circumference. The sealing element 42' has a slightly smaller outer diameter,

-12-

so that a small gap 60 remains between it and the cylindrical raceway 16. In this embodiment, if an unacceptably high pressure occurs inside the can, it is possible to additionally direct aerosol past the outside of the valve tappet 24 as soon as the sealing element 42 is lifted off the shoulder 44. This enables a faster pressure reduction, so that the risk of an explosive bursting of the aerosol spray can is further reduced.

The previously described axial grooves and radial grooves 58 also allow the can to be filled more quickly if the sealing element 20 between the valve plate and the valve tappet is designed in such a way that it opens up a passage when pressure is applied from the outside and the valve tappet 12 is pressed in.

Such a filling position is shown in Fig. 4 using the example of a slightly modified valve 10. When the valve tappet 24 is pressed, the pressure acting from the outside succeeds in deforming the sealing ring 20 inwards so that the filling material between the sealing ring edge and the outer surface of the valve tappet 24 can flow into the interior of the can. In contrast to the embodiment described in Figs. 1 to 3, the valve body 3 8 does not have axial grooves on its outer surface, but rather axial grooves on its sliding surface on the valve tappet.

A further difference between the embodiment shown in Fig. 4 and the previously described valves is a groove-like recess 64 in the area of the radial passage opening 36. The sealing element 42 forms a further improved seal with the walls of the groove 62, whereby in the rest position an axial contact of the

-13-

Sealing element 42 rests on the lower wall of the groove 64 and in the spray position the sealing element 42 rests on the upper wall of the groove 64.

Fig. 5 shows a further embodiment of a valve. This valve corresponds in its essential functional features to the previously described embodiments, but has the difference that an additional sleeve 66 is located in the valve housing 14, which on the one hand presses the sealing ring 20 against the valve plate 12 and on the other hand presses the sealing element 42 against the annular bead 46 on the shoulder 44. The interior of the sleeve 66 serves as a guide surface for the piston-like shoulder 26 and a sealing element 68, which in this case has an L-shaped cross section. The advantage of this embodiment is that the sleeve 66 partially supports the sealing element 42 against the internal pressure prevailing in the can, so that the spring element 40 can be dimensioned smaller for the same opening pressure. This significantly reduces the operating forces, so that only a significantly lower actuating force has to be exerted on the valve tappet to reach the spray position.

The valves are assembled by simply axially inserting the individual components into one another. Before the valve plate 12 with the inserted sealing ring 20 is flanged around the outer ring 22 of the valve housing 14, first the valve body 38 with the sealing element 42, then the coil spring 40 and finally the valve tappet 24 are inserted into the cylindrical raceway 16. An inner cam 62 can be provided on the open edge of the raceway 16 (see Fig. 2 and 4), which in the pre-assembled state takes up the load of the coil spring 40 and thereby prevents the valve tappet 24 from jumping out of the cylindrical raceway 16. This makes pre-assembly of the valve 10 independent of

depending on the installation in the valve plate 12. Gassing the can through the valve 10 is easily possible.

Fig. 6 shows a further embodiment of a valve 110 which has separate through-openings for the spray position and the position for reducing excess pressure. The valve tappet 124 has a radial through-opening 136 in the area of the valve plate 12, which is closed in this area by the sealing element 120 in the rest position. The valve tappet 128 is supported on the valve housing 114 via a spring element 140, with its piston-like shoulder 126 resting on the underside of the sealing ring 120. The outer flank of the piston 126 has grooves which, when the valve tappet 124 is pressed in, enable a connection between the through-opening 136 and the inside of the can.

The valve tappet 124 in the valve 110 consists of an upper part 128 and a cup-shaped lower part 129, which are connected to one another in a pressure-tight manner via an O-ring 102. In the bottom of the lower part 129, an overpressure opening 104 is provided, which is closed in the rest position by a sealing element 142, which is pressed by a valve body 138 with the aid of a spring element 141, which is arranged between the upper valve tappet part 128 and the valve body 138, against an annular bead 146 on the bottom of the lower part 129.

The advantage of this embodiment is that the two springs 140, 141 can be adapted in their preload force to their respective intended use, so that the operating forces can be reduced without changing the opening pressure for reducing excess pressure.

-15-

By selecting the spring strength of the spring element 141 accordingly, the opening pressure of the valve 110 can be set very precisely. In the valve 110, the gas passage takes place, depending on the valve position, between the axially interlocking elements through axial grooves in the area of the guide surfaces.

The lower part 129 of the valve tappet 124 is designed as a pipe end 132 with a conical end, which at maximum displacement rests against a conical stop 154 on the valve housing 114. The riser pipe 150 and the grooves 156 on the pipe end 132 are also found in this design.

The right half of the valve shown in Fig. 6 shows a slightly modified embodiment of the valve tappet 124 compared to the left half, in which the O-ring 102 is not located axially between the upper and lower parts 128, 129, but on a circumferential surface of the upper part 128, onto which the lower part 129 is placed.

In Fig. 7, another embodiment of a valve is shown that allows the filling process to be shortened. While the sealing ring 20 in the rest position (not shown) seals the valve plate 12 against the valve tappet 24 in a pressure-tight manner, it bulges inwards when the valve tappet 24 is pressed inwards and pressure is applied from the outside in accordance with the position shown. This opens up an annular gap 70 between the sealing ring 20 and the valve plate 12, which leads to a large number of grooves 72 that are incorporated into the annularly thickened outer wall 22 of the valve housing 14. This allows the aerosol with which the can is to be filled to flow not only through the cavity 34 inside the valve tappet 24, but also through the hollow space 34 inside the valve tappet 24.

the radial opening 36 and the axial grooves on the outer flank
of the piston 26 into the interior of the can, but there is another path available, which shortens the filling process.

The solution shown in Fig. 7 is a modification of the embodiment shown in Fig. 5, but this solution with the annular gap 70 and the grooves 72 can also be transferred to the other embodiments.

Claims (18)

m sayings 1. Aerosol can with a spray valve (10; 110) with an overpressure function located in its valve plate (12; 112), which has a valve housing (14; 114) which is open towards the interior of the can and sealed on the other side against the valve plate (12; 112) of the can housing, and a hollow valve tappet (2; 124) which is slidably arranged in the valve housing, which projects through the valve plate (12; 124) of the can and, in its depressed spray position, creates a connection between the interior of the can and the environment, and on which a valve body (38; 13 8) is provided which is axially movable against the force of a spring element (40; 141) prestressed between itself and the valve tappet (24; 124), which spring element (40; 141) in the closed rest position of the valve (10; 110) closes the valve body (38, 42; 138, 142) is preloaded against the internal pressure of the can against a tight fit (44, 46; 146), the valve tappet (24; 124) being preloaded by the spring element (40; 140) or a further spring element against a fit on the valve housing (14; 114) or on the valve plate (12; 112), characterized in that the passage to the cavity (34) of the valve tappet (24) consists of at least one radial passage opening (36) in the region of its end (32) projecting into the valve housing (14), and in the region of the valve body (38) a sealing element (42) is provided which seals the valve housing (14) against the valve tappet (24) at normal can pressure, the radial passage opening (36) being tightly closed by the sealing element (42) in the rest position. -2- 2. Aerosol can according to claim 1, characterized in that the interior of the valve housing (14) or of a sleeve arranged therein in its (or its) area facing the valve plate (12) is designed as a cylindrical bushing (16) in which the valve body (38) and the valve tappet (24) provided with a piston-like shoulder (26) are guided. 3. Aerosol can according to claim 1 or 2, characterized in that a sealing ring (20) is provided between the valve housing (14) and the valve plate (12). 4. Aerosol can according to claim 1 or 2, characterized in that the valve plate (12) is coated with polypropylene on the inside of the can. 5. Aerosol can according to one of the preceding claims, characterized in that the valve tappet (24) has a reduced diameter in the region of the radial passage opening (36). 6. Aerosol can according to the preamble of claim 1, characterized in that in the region of the valve plate (12) a radial passage opening (136) to the cavity (134) of the valve tappet (124) is provided, which in the rest position is supported by a (112) and the valve housing (114) provided sealing ring (120) is closed, and the valve body (138) is guided axially in the correspondingly enlarged cavity (134) of the valve tappet (124), wherein an opening (104) of the cavity (134) for reducing excess pressure in the rest position is closed by a sealing element (142) provided on the valve body (138) and the prestressing force of the spring element (141). -3- 7. Aerosol can according to claim S ₁ , characterized in that the valve tappet (124) consists essentially of two parts (128, 129), whereby the part (129) facing the interior of the can is cup-shaped, has the overpressure opening (104) on its underside, is fixedly arranged on the upper part (128) of the valve tappet (124) and accommodates the valve body (138), the sealing ring (142) and the spring element (141) between itself and the upper part (128). 8. Aerosol can according to one of the preceding claims, characterized in that a stop (54; 154) is provided on the valve housing (14; 114) for limiting the displacement path of the valve tappet (24; 124) in the spray position. 9. Aerosol can according to claim 8, characterized in that the end (32; 132) of the valve tappet (24; 124) facing the interior of the can is conical and the stop (54; 154) for limiting the displacement path is correspondingly conical. 10. Aerosol can according to claim 9, characterized in that the end of the valve tappet (24; 124) has radial grooves (56; 156) which form a passage even when in contact with the limit stop (54; 154). 11. Aerosol can according to one of the preceding claims, characterized in that in the contact area (44) of the sealing element (42) of the valve body (38) on the valve housing (14) or on the lower part (129) of the valve tappet (124) an annular bead (46; 146) is provided. -4- 12. Aerosol can according to claim 11, characterized in that the annular bead (46) has a triangular cross-section. 13. Aerosol can according to one of the preceding claims, characterized in that a radially inwardly pointing cam (62) is provided at the upper end in the cylindrical bushing (16). 14. Aerosol can according to one of claims 3 or 13, characterized in that an annular bead is provided on the valve housing (14) on the contact surface (18) between the valve housing (14; 114) and the sealing ring (20; 120) or the polypropylene layer on the valve plate (12). 15. Aerosol can according to one of claims 3 to 14, characterized in that the piston-like shoulder (26) of the valve tappet (24) in the rest position on the sealing ring (20) or the coated valve plate (12). 16. Aerosol can according to claim 13, characterized in that axial grooves are provided on the contact surface of the piston shoulder (26; 126) on the sealing ring (20; 120), the outer surface of the valve tappet (24; 124) and on the valve body (38; 138) and, if appropriate, a gap (60) is present between the sealing element (42) and the cylindrical raceway (16). 17. Aerosol can according to one of the preceding claims, characterized in that a riser pipe (50; 150) is attached to the lower end (48) of the valve housing (14; 114), which ends at the bottom of the can. -5- 18. Aerosol can according to one of the preceding claims, characterized in that an annular gap 70 is provided between the sealing ring 20 and the valve plate 120 and channels or grooves are provided between the valve housing 14 and the valve plate 12, the annular gap 70 and the grooves 72 being releasable when the can is pressurized from the outside and the valve tappet 24 is depressed.