WO2009063253A2

WO2009063253A2 - An aerosol can filling machine and hopper for use with the same

Info

Publication number: WO2009063253A2
Application number: PCT/GB2008/051076
Authority: WO
Inventors: Jean-Charles Julien
Original assignee: U-Pol Limited
Priority date: 2007-11-15
Filing date: 2008-11-17
Publication date: 2009-05-22
Also published as: GB0722470D0; WO2009063253A3

Abstract

An aerosol can filling machine has a piston (15,16) and dosage cup (4) for dispensing a dosage of flowable material into an aerosol can (8). The hopper (3) comprises a reservoir for storing the flowable material and a reservoir aperture through which said piston is moveable. A connector (2) is provided for connecting the reservoir to the dosage cup (4) and feeding flowable material thereto. The connecter (2) locating the reservoir between piston (15,16) and dosage cup (4) such that, in use, the piston (15,16) is moveable through the reservoir and into the dosage cup (4) for injecting a quantity of flowable material into the aerosol can (8). The aerosol can filling machine also having locator control means for preventing repeated operation until a locator switch (20) detects that the aerosol can (8) has been removed and replaced.

Description

AN AEROSOL CAN FILLING MACHINE AND HOPPER FOR USE WITH THE SAME

[001] The present invention relates to an aerosol can filling machine and a hopper for use therewith and, in particular, an aerosol paint can filling machine and a replaceable hopper for use with the same.

[002] In this connection, in many situations it is desirable to be able to provide an aerosol paint where the colour is customised or matched to a particular purpose. For example, for car body part repair, so that a replaced or repaired part can be coloured to match the surrounding parts.

Another example would be where a user needs to paint a relatively small batch of products the same customised colour .

[003] In a known system, pre-charged aerosol cans, charged with propellant, are supplied, for example, to a wholesaler, and a filling machine is used on site to inject a quantity of paint colour mixture into each aerosol can to produce a useable paint can of the desired colour. To do this, the wholesaler must firstly prepare a paint mixture of the desired colour, and then pour a predetermined quantity of this paint mixture into the injection cup or cylinder provided in the filling machine. The filling machine then forces a piston into the injection cup, thereby forcing the paint mixture out through an opening in the cup and into the pressurised aerosol can through a valve in the can. This allows a wholesaler to prepare aerosol cans of any required colour by injecting different paint colour mixtures into the aerosol can.

[004] The above system has been successful in instances where a wholesaler produces paint cans of one-off colours, for example when a customer requires a single can of a particular colour. However, this system can be relatively slow when producing multiple paint cans of the same colour. Furthermore, a particular customer may regularly require batches of a number of customised colours. To do this, a wholesaler must prepare a paint colour mixture for each of the desired colours each time the customer requires a batch. This is time consuming and can be difficult for the wholesaler to ensure colour consistency between batches.

[005] In the above situation, because relatively low numbers of each colour paint can are produced (typically less than 10 cans), industrial type mass production machines, which utilise precision valve and pumping mechanisms to dispense measured doses, are unsuitable. This is because of their complexity and cost, as well as the difficulty of cleaning these machines if different colours are to be used. Wholesalers therefore require a simple reliable system that can as easily produce 1 paint can of a desired colour, as it can a small batch of paint cans.

[006] A further important factor is the issue of ensuring the correct volume of the paint colour mixture injected into the can. As the pre-charged aerosol cans are supplied pre-pressurised, it is important that no more than a predetermined quantity of paint colour mixture is injected into the can, depending on the can size and pressure. Overfilling of the aerosol can risks exceeding its pressure tolerance, which can lead to explosive fracture of the can and hence presents a serious safety concern. In contrast, under filling the aerosol can could result in, for example, poor lifespan performance or paint dilution. In the past, because the introduction of the paint colour mixture into the cup or cylinder was performed manually, there was a risk that a user might under or overfill the dosage cup or cylinder. Moreover, of more major concern was a user accidentally injecting two loads or doses of paint colour mixture into the same can, so-called "double dosing". Double dosing presents a significant hazard to not only the user preparing the can, but also to future customers, since the can could rupture at any point. Nevertheless, any safety mechanism designed to avoid such problems must not compromise the simplicity and the reliability of the system.

[007] It is therefore an object of the present invention to seek to address the problems associated with the prior art.

[008] According to an aspect of the present invention there is provided a hopper for use with an aerosol can filling machine, the machine having a piston moveable into a dosage cup for dispensing a dosage of flowable material into an aerosol can, said hopper comprising: a reservoir for storing the flowable material and comprising a reservoir aperture through which said piston is moveable; and a connector for connecting the reservoir to the dosage cup and for defining a channel for feeding flowable material from the reservoir to the dosage cup; wherein the connector, in use, locates the reservoir between piston and dosage cup such that the piston extends through the reservoir aperture and is moveable through the reservoir and into the dosage cup to dispense a dosage of flowable material.

[009] In this way, a simple hopper system is provided capable of feeding flowable material, such as a paint mixture, into the dosage cup for injection into an aerosol can. This allows for multiple aerosol cans to be filled quickly with the same type and quantity of fluid, without requiring any or significant modification of the dosage cup, or the installation of complex pumping and valve mechanisms which would otherwise be required for dispensing measured - A - doses. Accordingly a cheap and mechanically reliable system is provided. Moreover, the hopper can be conveniently removed from the dosage cup, allowing for use of the filling machine without the hopper, i.e. for one off filling operations, and the ability to use different hoppers for different flowable materials, such as different mixtures of paint.

[0010] Conveniently, the flowable material is a fluid.

[0011] Conveniently, the flowable material is a paint mixture. This allows multiple aerosol cans of the same colour paint to be quickly produced on a small batch scale.

[0012] Conveniently, there is provided a closure for sealing the channel when the connector is disconnected from the dosage cup. Moreover, there may be further provided a closure for sealing the reservoir aperture when the hopper is disconnected from the aerosol can filling machine. In this way, different hoppers can be used to store different flowable materials, and then can be attached by an operator as and when required. For example, a paint wholesaler may store within different hoppers a number of custom paint colour mixtures for regular customers. When a customer requires one or more aerosol cans in their custom colour, the wholesaler can quickly provide this colour simply by connecting the relevant hopper to the filling machine.

[0013] Conveniently, the reservoir may comprise a sloped surface for funnelling flowable material towards the channel. In this way, paint in the hopper can be funnelled into the dosage cup.

[0014] According to a further aspect of the present invention, there is provided an aerosol can filling machine, comprising: a dosage cup for storing a predetermined quantity of flowable material and having a nozzle for injecting said flowable material into an aerosol can; a piston moveable into the dosage cup for forcing the flowable material in the dosage cup through the nozzle; movement means for moving the piston relative to the dosage cup; and a hopper comprising a reservoir for storing the flowable material, and a channel for feeding flowable material into the dosage cup; wherein said piston is moveable through the reservoir and into the dosage cup for injecting the predetermined quantity of flowable material in the dosage cup into the aerosol can.

[0015] In this way, the hopper provides flowable material, such as a paint mixture, to the dosage cup, allowing multiple aerosol cans to be filled quickly with the same type and quantity of flowable material. Furthermore, the system is simple and reliable, and accurate doses can be measured and dispensed without requiring the installation of complex pumping and valve mechanisms which would otherwise be required.

[0016] Conveniently, the flowable material is a fluid, and preferably, it is a paint mixture.

[0017] Conveniently, the hopper further comprises a connector for detachably connecting the hopper to the dosage cup. This allows for the ability to easily connect different hoppers to the machine so that, for example, different flowable materials, such as different paint mixtures, stored in different hoppers can be quickly connected to the machine. Furthermore, the hopper could be disconnected altogether allowing the filling machine to be used without the hopper, i.e. for one off filling operations.

[0018] Conveniently, the connector defines the channel for feeding fluid into the dosage cup. In this way, the connector is able to align and feed fluid into the dosage cup, leading to a mechanically simple design.

[0019] Conveniently, said movement means further comprises means for moving an aerosol can into a dispensing position where its valve is engaged with the nozzle for injecting fluid from the dosage cup into the aerosol can. In this way, the aerosol can is moved between a non-dispensing position and a dispensing position. Accordingly, the aerosol can be correctly filled when in the dispensing position. Furthermore, when the aerosol can is in the non-dispensing position, it can be easily removed from the machine, since it is no longer engaged with the nozzle. This allows quick replacement of aerosol cans when filling multiple cans in the same batch.

[0020] Conveniently, the nozzle comprises a valve mechanism for preventing the passage of flowable material through the nozzle when said aerosol can is not in a dispensing position. In this way, flowable material is prevented from leaking from the dosage cup when the nozzle and aerosol can valve are not engaged.

[0021] Conveniently, there is further provided a locator for locating the aerosol can to align its valve with the nozzle of the dosage cup. In this way, an operator can easily and accurately position the aerosol can to ensure the fluid in the dosage cup is correctly injected into the can.

[0022] Conveniently, there is further provided a locator switch for detecting an aerosol can located at the locator; and a locator control means for preventing repeated operation of said movement means until said locator switch detects that the aerosol can has been removed and replaced. In this way, the risk of double dosing the aerosol can is significantly reduced as a user must remove a can that has been dosed before they can repeat the injection operation.

[0023] Conveniently, said locator control means prevents operation of said movement means unless the locator switch detects an aerosol can located at the locator. In this way, premature or accidental injection is prevented, which may otherwise damage the filling machine.

[0024] Conveniently, the locator switch and the locator control means employ a fluid controlled circuit. This avoids the risks of electrical sparking which would be associated with electrical circuits. Such sparks could ignite solvents and propellants in the aerosol.

[0025] Conveniently, there is further provided an enclosure having a safety door being closable for protecting an operator during operation of said movement means.

[0026] Conveniently, there is further provided a door switch for detecting if said safety door is closed; and door control means for preventing operation of said movement means unless the safety door is closed. In this way, operation of the filing machine is prevented if the safety door is accidentally left open.

[0027] Conveniently, said door switch is recessed within the enclosure, and the safety door is provided with a protrusion for engagement with the recessed door switch when the safety door is closed. In this way, it is more difficult to tamper with the door switch thereby avoiding dangerous operation of the filling machine.

[0028] Conveniently, the door switch and the door control means employ a fluid controlled circuit. This avoids the risks of electrical sparking which would be associated with electrical circuits. Such sparks could ignite solvents and propellants in the aerosol.

[0029] Conveniently, there is further provided a hopper protection switch for stopping operation of said movement means before a support supporting the piston engages with the reservoir. In this way, accidental damage of the reservoir and hopper is prevented.

[0030] Conveniently, said movement means is powered by a fluid controlled piston. Pneumatics provide a lightweight, powerful and spark free movement for actuating the filling machine .

[0031] Conveniently, said locator control means and/or said door control means prevent operation of said movement means by stopping gas entering the cylinder of said fluid controlled piston. In this way, movement of the movement means can be directly prevented without having to use electrics or complex control circuitry.

[0032] Conveniently, the aerosol can filling machine may further comprise a counter for counting the doses of flowable material remaining in said reservoir. In this way, accidental under-filling of the aerosol can be avoided, in the even that there is insufficient flowable material in the reservoir to fill the dosage cup.

[0033] According to a further aspect of the present invention, there is provided a hopper for use in the above aerosol can filling machine.

[0034] According to yet a further aspect of the present invention, there is provided an aerosol can filling machine, comprising: a dosage cup for storing a predetermined quantity of flowable material and having an nozzle for injecting said flowable material into an aerosol can positioned at a dosing location; a piston moveable into the dosage cup for forcing the flowable material in the dosage cup through the nozzle; movement means for moving the piston relative to the dosage cup; a locator switch for detecting an aerosol can located at the dosing location; and a locator control means for preventing repeated operation of said movement means until said locator switch detects that the aerosol can has been removed and replaced. In this way, accidental double dosing of the aerosol can is avoided.

[0035] Conveniently, the locator switch and locator control means employ a fluid controlled circuit.

[0036] An illustrative example of the present invention will now be described in detail with reference to the accompanying drawings in which: - Figure 1 shows a hopper can and a connector prior to connection to the hopper can;

Figure 2 shows the connector connected to the hopper can, with the connector closure removed;

Figure 3 shows the hopper can, the connector and the dosage cup;

Figure 4 shows the dosage cup connected to the hopper can, via the connector, and the hopper can lid removed;

Figure 5 shows an aerosol can filling machine once the hopper can and dosage cup have been introduced; Figure 6 shows the aerosol can filling machine shown in Figure 5 after the lower platform has been raised to engage the aerosol with the dosage cup; and

Figure 7 shows the aerosol can filling machine shown in Figure 6 after the lower platform has been further raised such that the piston is forced through the cylinder of the do sage cup .

[0037] Figures 1 to 4 show a hopper assembly according to an embodiment of the present invention. Hopper can 3, which forms the reservoir of the assembly, is a 2.5 litre paint can similar to a standard paint can, although an end thereof is provided with an aperture into which the connector 2 can be fitted. The connector 2 has a central aperture and once inserted into the aperture of hopper can 3, the connector 2 is held in place by engagement with the rim thereof, such that a portion of the connector protrudes from the end of the hopper can 3 (see Figure 2) . The protruding portion of the connector 2 is provided with a threaded section to which the connector lid 1 is detachably connected. Once the connector lid 1 has been detached, the threaded section of connector 2 is exposed (see Figure 2) . This allows the dosage cup 4 to be screwed onto threaded section of connector 2, as shown in Figures 3 and 4. This connects the interior of the hopper can 3 with the cylinder of the dosage cup 4 through the aperture provided in the connector 2.

[0038] Figure 4 shows assembled hopper can 3 and dosage cup 5. In this figure, this assembly is rotated from its position shown in figure 3 to its in use position. Hopper can lid 3a is removed to expose an aperture through which the hopper can 3 can be filled with paint of a desired colour or type.

[0039] Figures 5 to 7 show the aerosol can filling machine according to an embodiment of the present invention.

[0040] The dosage cup 4 is slotted into a channel provided in upper platform 6 of the aerosol can filling machine. The dosage cup 4 is provided with two ribs which act as a keying arrangement with the ends of the channel provided in the upper platform 6, thereby preventing horizontal movement of - li the dosage cup 4 relative to the upper platform 6.

[0041] The connector 2 connects the hopper can 3 to the dosage cup 4 and, once the dosage cup 4 is positioned in the upper platform 6, the connector 2 locates the hopper can 3 such that piston 16 and its tip 15 are positioned within the reservoir of the hopper can 3. To facilitate installation of the dosage cup 4 and hopper can 3, piston 16 can be disconnected from the filling machine and reattached once the dosage cup 4 and hopper can 3 is in position.

[0042] The lower platform 9 of the aerosol can filling machine is provided with a locator placement 10 onto which aerosol can 8 is placed. A safety frame 13 is provided to brace the aerosol can 8 during the filling operation. When the lower platform 9 is in its lowered position, as shown in Figure 5, there is a gap provided between the top of aerosol can 8 and the safety frame 13 and valve section 14 of dosage 4. This allows the aerosol can 8 to be easily removed and replaced between dosage operations.

[0043] Locator switches 20 are provided either side of the locator placement 10 to detect when an aerosol can 8 is placed on the locator placement 10. The locator switches 20 form part of a pneumatic circuit (not shown) connected to air cylinder 11 which prevents operation of the filling machine when an aerosol can 8 is not installed, by preventing airflow into pneumatic cylinder 11 which would actuate pneumatic piston 12. Furthermore, the pneumatic circuit contains a logic circuit which prevents repeat operation of the filling machine until the locator switches 20 detect that a can has been removed and replaced, to thereby reduce the risk of double dosing a single a

[0044] The filling machine is further provided with a safety door switch 18 for detecting when the safety door (not shown) of the filling machine is closed. In this connection, the safety door is provided on the front of the machine for protecting the operator during the operation cycle. The door switch 18 is provided recessed within a casing which prevents unauthorised tampering. As the safety door is shut, a protrusion provided on the inner surface of the door enters the casing and depresses the door switch 18. The door switch 18 is connected to a pneumatic circuit (not shown) which prevents operation of the filling machine, by preventing airflow into pneumatic cylinder 11, when the safety door 8 is not closed.

[0045] Figure 5 shows the filling machine at the beginning of its operation cycle, where both the upper and lower platforms 6 and 9 are at their lower position. The hopper can 3 and dosage cup 4 are positioned within the filling machine. In this position, the dosage cup 4 is held spaced from the tip 15 of piston 16, thereby allowing paint held within the reservoir of hopper can 3 to flow into and fill the dosage cup 4. Dosage cup 4 is sized to measure a predetermined quantity of paint. Valve mechanism 14 provided in the lower portion of dosage cup 4 prevents paint held within the dosage cup 4 from dripping.

[0046] An aerosol can 8 to be filled is placed on the placement locator 10 by an operator. In doing this, locator switches 20 are depressed by the aerosol can 8. The safety door (not shown) is then closed by the operator which depress door switch 18. Once the locator switches 20 and door switch 18 are depressed, a pneumatic gate (not shown) is opened which, when an operator activates the filing machine to do so, permits air to enter pneumatic cylinder 11. In this way, the machine cannot be operated unless an aerosol can 8 is correctly inserted and the safety door is closed. [0047] On activation by an operator, pneumatic cylinder 11 forces its pneumatic piston 12 upwardly, thereby rasing lower platform 9, such that it moves to the position shown in Figure 6. In this position, the safety frame braces the aerosol can 8 and aligns its valve with the valve mechanism

14 of dosage cup 4. The valve mechanism 14 is configured to couple with and open the valve of the aerosol can 8.

[0048] As lower platform 9 moves to the position shown in Figure 6, supports 7 move upwardly relative to the upper platform 6 and engage with corresponding supports on the upper platform 6. This spaces the upper and lower platforms a predetermined distance apart, sized such that the aerosol can 8 is clamped between the valve mechanism 14 of dosage cup 4 and the lower platform 9. This holds the aerosol can 8 in position to ensure good transmission of paint from the dosage cup into the aerosol can 8.

[0049] As the lower platform 6 continues to move upwardly, supports 7, by virtue of their engagement with corresponding supports on the upper platform 6, force the upper platform upwardly. This moves the dosage cup 4 upwardly such that tip

15 of piston 16 moves into the dosage cup 4, as shown in Figure 6. This prevents further paint entering the dosage cup

4 and hence controls the amount of paint to be dispensed.

[0050] As the lower platform 9, and hence upper platform 6, moves further upwardly, the tip 15 of piston 16 is forced further down into the dosage cup 4, as shown in Figure 7.

This forces the paint contained in the cup out through the valve mechanism 14 and into the aerosol can 8.

[0051] Once the tip 15 has forced the paint contained in the dosage cup 4 into the aerosol can 8, as shown in Figure 7, the dosage cup 4 is lowered, thereby removing the tip 15 from the dosage cup 4. This is achieved by the pneumatic cylinder 11 retracting pneumatic piston 12, thereby lowering the lower platform 9, which in turn pulls upper platform 6 downwardly. At the same time, this causes the lower platform 9 to move away from upper platform 6 in order to separate the aerosol can 8 from the valve mechanism 14 and dosage cup 4, as shown in Figure 5. This allows the aerosol can 8 to be removed and replaced with the next can to be filled. Furthermore, as the tip 15 of piston 16 moves out of the dosage cup 4, the dosage cup 4 can refill with paint from the hopper can 3 reservoir, thereby allowing the filling process to be repeated as soon as a new aerosol can 8 has been inserted into the machine.

[0052] The after use, the hopper 3 and dosage cup 4 can be removed from the filing machine. The hopper can lid 3a shown in Figure 4 can be reattached to seal the top of the hopper, and the dosage cup 4 can be detached and connector lid 1 reattached to the threaded section of connector 2 shown in Figure 2. The dosage cup 4 can be cleaned ready to subsequent use. In this way, the contents of the hopper 3 can be easily stored for use later. This allows a user to keep a stock of customised paint colours, with each colour stored in a different hopper. When required, the respective hopper of the desired colour can be attached to the filling machine and one or more aerosol cans can be filled with the desired colour.

[0053] As discussed above, the filling machine employs various safety mechanisms to prevent misuse. In addition to the aerosol can location switches 20 and the safety door switch 18 discussed above, hopper protection switch 5 is further provided. This switch prevents damage to the hopper 3 that may occur if the hopper 3 is raised to a position where it impacts with the roof of the machine and the supports supporting the piston 16.

[0054] Although the present invention has been described based on the above illustrated embodiment, the present invention is not limited solely to these particular embodiments .

[0055] For example, it will be understood that although the hopper and connector have been described as separate components, the hopper could have the connector formed integrally therein.

[0056] Furthermore, the hopper may be provided with a sloped surface on the end having the aperture into which the connector 2 can be fitted. In this way, paint in the hopper can be funnelled into the dosage cup.

[0057] Furthermore, if part of the connector 2 protrudes into the hopper, one or more apertures may be provided in this section for draining any remaining paint from the hoper into the dosage cup.

[0058] Moreover, although the filling machine in the above illustrative example employs pneumatics, it will be apparent that alternative fluid operated systems could be used, such as hydraulics.

[0059] Finally, a dosage counter may be provided on the filling machine to indicate when a particular hopper is about to run out of paint. That is, if a hopper contains just over

2 litres of paint, and each dose is 100ml, the counter could count down from 20 doses. When the counter reaches 0, a user will be alerted that they need to re-fill the hopper. This avoids a user accidentally under-filling an aerosol can in the event that the remaining paint in the hopper is insufficient to fill the dosage cup.

Claims

1. A hopper for use with an aerosol can filling machine, the machine having a piston moveable into a dosage cup for dispensing a dosage of flowable material into an aerosol can, said hopper comprising: a reservoir for storing the flowable material and comprising a reservoir aperture through which said piston is moveable; and a connector for connecting the reservoir to the dosage cup and for defining a channel for feeding flowable material from the reservoir to the dosage cup; wherein the connector, in use, locates the reservoir between piston and dosage cup such that the piston extends through the reservoir aperture and is moveable through the reservoir and into the dosage cup to dispense a dosage of flowable material.

2. A hopper according to claim 1 wherein the flowable material is a fluid.

3. A hopper according to claim 1 or 2 wherein the flowable material is a paint mixture.

4. A hopper according to any proceeding claim further comprising a closure for sealing the channel when the connector is disconnected from the dosage cup.

5. A hopper according to any preceding claim further comprising a closure for sealing the reservoir aperture when the hopper is disconnected from the aerosol can filling machine .

6. A hopper according to any preceding claim wherein said reservoir comprises a sloped surface for funnelling flowable material towards said channel.

7. An aerosol can filling machine, comprising: a dosage cup for storing a predetermined quantity of 5 flowable material and having an nozzle for injecting said flowable material into an aerosol can; a piston moveable into the dosage cup for forcing the flowable material in the dosage cup through the nozzle; movement means for moving the piston relative to the 10 dosage cup; and a hopper comprising a reservoir for storing the flowable material, and a channel for feeding flowable material into the dosage cup; wherein said piston is moveable through the reservoir 15 and into the dosage cup for injecting the predetermined quantity of flowable material in the dosage cup into the aerosol can.

8. An aerosol can filling machine according to claim 7, 20 wherein the flowable material is a fluid.

9. An aerosol can filling machine according to claim 8, wherein the flowable material is a paint mixture.

25 10. An aerosol can filling machine according to any one of claims 7 to 9, wherein the hopper further comprises a connector for detachably connecting the hopper to the dosage cup.

30 11. An aerosol can filling machine according to claim 10, wherein the connector defines the channel for feeding flowable material into the dosage cup.

12. An aerosol can filling machine according to any one of 35 claims 7 to 11, wherein said movement means further comprises means for moving an aerosol can into a dispensing position where its valve is engaged with the nozzle for injecting flowable material from the dosage cup into the aerosol can.

5 13. An aerosol can filling machine according to claim 12, wherein the nozzle comprises a valve mechanism for preventing the passage of flowable material through the nozzle when said aerosol can is not in a dispensing position.

10 14. An aerosol can filling machine according to any one of claims 7 to 13, further comprising a locator for locating the aerosol can to align its valve with the nozzle of the dosage cup.

15 15. An aerosol can filling machine according to claim 14, further comprising a locator switch for detecting an aerosol can located at the locator; and a locator control means for preventing repeated operation of said movement means until said locator switch detects that the aerosol can has been

20 removed and replaced.

16. An aerosol can filling machine according to claim 15, wherein said locator control means prevents operation of said movement means unless the locator switch detects an aerosol

25 can located at the locator.

17. An aerosol can filling machine according to claims 15 or 16, wherein the locator switch and the locator control means employ a fluid controlled circuit.

30

18. An aerosol can filling machine according to any one of claims 7 to 17, further comprising an enclosure having a safety door being closable for protecting an operator during operation of said movement means.

35

19. An aerosol can filling machine according to claim 18, further comprising a door switch for detecting if said safety door is closed; and door control means for preventing operation of said movement means unless the safety door is closed.

20. An aerosol can filling machine according to claim 19, wherein said door switch is recessed within the enclosure, and the safety door is provided with a protrusion for engagement with the recessed door switch when the safety door is closed.

21. An aerosol can filling machine according to any one of claims 16 to 20, wherein the door switch and the door control means employ a fluid controlled circuit.

22. An aerosol can filling machine according to any one of claims 7 to 21, further comprising a hopper protection switch for stopping operation of said movement means before a support supporting the piston engages with the reservoir.

23. An aerosol can filling machine according to any one of claims 7 to 22, wherein said movement means is powered by a fluid controlled piston.

24. An aerosol can filling machine according to claim 23 when dependent on claims 17 or 21, wherein said locator control means and/or said door control means prevent operation of said movement means by stopping fluid entering the cylinder of said fluid controlled piston.

25. An aerosol can filling machine according to any one of claims 7 to 24, further comprising a counter for counting the doses of flowable material remaining in said reservoir.

26. A hopper for use in the aerosol can filling machine according to any one of claims 7 to 25.

27. An aerosol can filling machine, comprising: a dosage cup for storing a predetermined quantity of flowable material and having an nozzle for injecting said flowable material into an aerosol can positioned at a dosing location; a piston moveable into the dosage cup for forcing the flowable material in the dosage cup through the nozzle; movement means for moving the piston relative to the dosage cup; a locator switch for detecting an aerosol can located at the dosing location; and a locator control means for preventing repeated operation of said movement means until said locator switch detects that the aerosol can has been removed and replaced.

28. An aerosol can filling machine according to claim 27, wherein said locator switch and locator control means employ a fluid controlled circuit.

29. A hopper substantially as hereinbefore described with reference to the accompanying drawings.

30. An aerosol can filling machine substantially as hereinbefore described with reference to the accompanying drawings .