GB2054413A - Rotary atomiser - Google Patents

Abstract

Rotary atomising head 1 of the type that in operation a zone of reduced pressure is created in the region of a liquid inlet 38 to the atomising head, has a liquid supply system comprising a closed container 5 for liquid having an outlet 33 which is connected by a duct 6 to the atomising head inlet 38 and a vent 34 connected to the atmosphere, in the region of the lower part of the container. The container 5 is arranged relative to the atomising head such that the atomising head inlet 38 is above the level of the container outlet 33 so that, when the head is not in use, the liquid in the container is in equilibrium with the level of the liquid in the duct 6 intermediate the atomising head inlet 38 and the container outlet 33, the reduced pressure created in the atomising head 1 being sufficient to draw liquid from the duct to the atomising head inlet. The vent 34 may be connected to a reservoir 35 for receiving excess liquid when the head is not in use. <IMAGE>

Description

SPECIFICATION Improvements in and relating to spraying apparatus The present invention relates to improvements in spraying apparatus and particularly, but not exclu- sively, to spraying apparatus designed to be fixedly mounted, for example on a wall adjacent an entrance to an animal enclosure to spray the animates as they enter the enclosure.

Portable spraying apparatus comptrising a rotary atomising head for providing a fine mist of a liquid to be sprayed and a fan for blowing the spray forwardly, is well known. In such apparatus, the liquid is generally supplied to the atomising head under gravity and the apparatus is arranged to have a storage position in which the liquid container is below the atomising head and a use position in which the container is above the atomìsing head so that liquid will, in this position of the apparatus, flow under gravity to the atomising head.

Such apparatus when intended to be fixedly mounted thus has the disadvantage that the apparatus has to be mounted to stop flow of liquid to the atomising head. It has been proposed to-overcome this disadvantage by providing an electrically operated valve in the liquid supply line to the atomising head. However this solution not only increases the cost of the apparatus but also introduces into the apparatus another component which requires servicing and which can produce leakage problems. As an alternative, it has been proposed to supply the atomising head with liquid using a pump rather than gravity. This solution yet further increases the cost of the apparatus and has the same disadvantages as the provision of a valve.

It has been found that the rotary atomising heads which are presently used have the feature, which is not utilised in their operation of producing a region of reduced pressure at the point of entry of 17quid into the head. According to the present invention, it is proposed to utilise this feature in connection with a form of gravity feed which is controlled hydrostatically and not by the provision of any additional moving components.

According to the present invention there is provided a spraying apparatus comprising an atomising head having an inlet for liquid to be atomised thereby, the atomising head being such that in operation a zone of reduced pressure is created in the region of the inlet, a closed container for liquid having an outlet and a vent in the region of a lower part thereof, the container outlet being connected to the atomising head inlet by a duct and the vent being in communication with the atmosphere, the container being arranged relative to the atomising head such that the atomising head inlet is above the level of the container outlet so that, when the apparatus is not in use, the liquid in the container is in equilibrium with the level of liquid in the duct intermediate the atomising head inlet and the container outlet, the reduced pressure created in the atomising head in use being sufficient to draw liquid from the duct to the atomising head inlet.

Preferably the container vent communicates with a reservoir for receiving liquid when the apparatus is not in use.

The container vent may open into a reservoir which is open to the atmosphere above the level of the liquid in the duct when the apparatus is not in use. The reservoir may have sufficient capacity to accommodate excess liquid when the apparatus is not in use of may be connected to an auxiliary reservoir by a weir which may be at a level above the equilibrium level of liquid in the duct when the apparatus is not in use.

The reservoir may take the form of an upwardly extending and-upwardly open pipe connected to the vent. The auxiliary reservoir where provided may take the form of a bottle connected to a pipe branching therefrom.

The present invention will be more fully un'der- stood from the following description of embodiments thereof, given by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a side view of an embodiment of spraying apparatus according to the present invention; Figure 2 is a view from the front of the appa ratus of-Figure 1; - Figures 3, 4 and 5 are diagrammatic views of part ofthe apparatus of Figures 1 and 2 illustrating operation of the apparatus; Figure 6 is a diagrammatic view similar to the views of Figures 3 to 5 and showing a modification of the apparatus of Figure 1;; Figure 7 is a diagrammatic view of part of the apparatus of Figure 1 showing a modification thereof; Figure 8 is a diagrammatic view similar to that of Figure 7 showing a further modification of the apparatusoffigurel; Figure 9 is a section on the line IX-IX of Figure 8; and Figure 10 is a section through an embodiment of atomising heads for use in the apparatus of Figure 1.

The spraying apparatus shown in Figures 1 and 2 comprises a rotary atomising head 1 which is mounted at the front end of a generally cylindrical casing 2 housing a motor for driving the head 1 and for driving a fan 3 mounted at the rear end of the casing 2. The rotary head 1 produces a radial spray of atomised particles of liquid which are driven.

forward-in the direction of the arrows 4 by-the action of the fan 3. The fan is shown diagrammatically in Figures 1 and 2 and comprises, as is conventional, blades rotating within a protective frame which is illustrated in outline in Figures 1 and 2. Liquid is supplied to the atomising head from a container 5 via a pipe 6.

The apparatus al-so comprises a supporting frame- work comprising bars 8 extending generally parallel to the axis of the head 1 and fan 3 and connected to the casing 2 and framework of the fan 3 by radial members 9. The container 5 may, as shown, be mounted on one of the members 9 by a plate 10 which is welded or bolted to the lower end of the container and to the member 9.

As shown the apparatus is intended to be mounted on a generally vertical wall 11 to which is attached by any suitable means a mounting plate 12.

A generally U-shaped bracket 13 is mounted with its base connected to the plate 12 and its arms extending forwardly. Each of the lower framework bars 8 is provided with a fixing plate 14 which is welded or bolted thereto and which is pivotally connected to the respective arm of the bracket 13. The apparatus can thus pivot in the direction of the arrow 14 about axis 16 relative to the bracket 13. The limits of pivotal movement are set by engagement of a bolt 17 extending through the bracket 13 and engaged in a slot 18 in the plate 14 and the apparatus can be fixed in any selected position relative to the bracket 13 by tightening of for example a wing nut 19 on the bolt 17. Thus the relative orientation of the spray from the apparatus can be adjusted about the axis 16.

Additionally, and for reasons which will become apparent from the following description, the apparatus is mounted so that it can be inverted. As shown bracket 13 is pivotally mounted relative to the plate 12 for pivotal movement about an axis 20 in the direction of the arrow 21. The apparatus is in use held in the position shown in Figures 1 and 2 by any suitable releasable locking device 22. As shown the locking device comprises a latch which engages the base of the bracket 13 and is pivotally mounted on a flange 23 extending from the plate 12, which flange also serves as an abutment for correctly locating the bracket 13 in its operative position, and therefore the spraying apparatus itself.

It will be appreciated that the apparatus may be mounted by other means than those shown, to be adjustable and invertable.

The supply of liquid to the atomising head 1 will now be described with particular reference to Figures 3 to 5. As shown, the container 5 is in the form of an inverted bottle 30 having a threaded neck 31 which is threaded into a holder 32 which is mounted by plate 10 on the frame of the apparatus. The container has an outlet 33 which is provided in the holder 32 and is connected to pipe 6, and a vent 34 which is also provided in the holder.The vent 34 is connected to an upwardly extending pipe 35 with an open upper end and which constitutes the reservoir and pipe 35 has a branch pipe 36 which may, as shown, be connected to a vented bottled 37, the branch pipe 36 forming a weir and the bottle 37 an auxiliary reservoir, It will be noted that in uSe the level B of the liquid inlet 38 in the atomising head 1 is above the levels of the outlet 33 and vent 34, and that the level of the connection of branch pipe 36 to pipe 35 is intermediate the levels of the inlet 38 and outlet 33. These levels are arranged so that the supply of liquid to the atomising head is effected as follows.

In setting up the apparatus for use, with the apparatus inverted by being rotated through 1800 about axis 20 from the position shown in Figure 2, a full bottle 30 of liquid is connected to the holder 32.

The apparatus is then rotated back to the position shown in Figure 1. Liquid flows from the bottle 30 and into the pipes 6,35 until the level A of liquid in the bottle 30 reaches an equilibrium position in which the reduced pressure above the liquid in the bottle balances the head of liquid in the bottle. As shown, more liquid flows out of the bottle 30 than can be accommodated in the pipe 35 and therefore flows out of branch pipe 36, which serves as the weir, into bottle 37. Thus during the establishment of equilibrium the level of liquid in pipe 6 does not exceed level C of the branch pipe and therefore no liquid flows to the atomising head. In this initial condition, equilibrium will be established with the liquid pipes 6 and 35 at the lower level of the weir formed by the branch pipe 36.

To operate the apparatus, the motor is started to startthe atomising head 1 and fan 3 rotating. The atomising head is designed to create a reduced pressure in the zone of the inlet 38. The atomising head is adapted to provide a specific level of reduced pressure which may for example be of the order of 0.0875 N/cm2 (3" WG). This reduced pressure is designed to be sufficient to draw liquid up pipe 6 and into the atomising head where it is atomised and sprayed out of the head. As liquid is drawn from pipe 6 the remaining liquid in pipe 35 is drawn back into the container 5 and then air is drawn into the container 5 to allow the liquid to be drawn from the container into pipe 6. This condition is shown in Figure 4.

When the apparatus is to be stopped, the motor is switched off and automatically the supply of liquid to the atomising head is stopped because the pressure within the atomising head returns to atmospheric pressure. The level of liquid in pipe 6 drops to a level E (Figure 5) which is designed to be below the level of the weir provided by the branch pipe 36. The volume of pipe 35 between vent 34 and the branch pipe 36 is designed to be sufficient to accommodate the volume of liquid in pipe 6 between level E and inlet 38. Thus at this time no further liquid flows into bottle 37.

There is thus provided a method of supplying liquid to an atomising head using a system of gravity feed but controlling it hydrostatically rather than by the use of valves. The supply system thus includes no moving parts which require servicing. if expansion of the liquid in container 5 occurs, due for example to a rise in the ambient temperature, liquid expelled from container 5 will flow into pipe 35 and may overflow into container 37.

It will be appreciated that many modifications can be made to the above described apparatus, particularly as regards the pipework connected to the vent 34 to provide the primary reserovirfor liquid when the apparatus is in the condition shown in Figure 5.

For example, as shown in Figure 6, the threaded neck 31a of the bottle 30 may be adapted to define the vent with the holder and to define a reservoir within the holder. As shown in Figure 6, the neck 31a has a reduced section end portion 40 defining an annular space 41 between it and the holder 32. The lower end 42 of this annular space forms the vent and the annular space is connected towards its upper end to a pipe 43 which serves as a weir and is connected to the bottle 37 and has an upwardly opening branch pipe 44. In operation, when the apparatus is in use, the annular space 41 is filled with air and bubbles flow therefrom into the bottle 30.

When the motor is switched off, the liquid flowing backward from the pipe 6 fills the space 41, which may be sufficient to accommodate it, without loss of liquid to the bottle 37. Alternatively some of the liquid flows through the pipe 43 into the bottle 37.

In another modification, the need for an auxiliary reservoir can be avoided by increasing the volume of the main reservoir, for example as shown in the embodiments of Figures 7,8 and 9. In Figure 7, a pipe 65 is provided which is similar to pipe 35 of Figure 3 but has a larger volume so as to accommodate liquid flowing out of the container both when the apparatus is initially set up for use and when operation of the apparatus is stopped.

The upper end of the pipe 65 is closed and the pipe is open to the atmosphere at a level intermediate the ends of the pipe 65 through a smaller diameter pipe 66 which extends into pipe 65. The two pipes 65,66 define a closed annular volume 66,67 in the upper end of pipe 65 for receiving liquid when the apparatus is inverted. The pipe 66 is open to the atmosphere through a lateral opening 68 to prevent interference between the venting of the apparatus in use and air blown round pipe 67 by the fan.

In the embodiment of Figure 7, the connections to the holder 32 are simplified, the holder 32 being laterally extended by a duct 69 from which the pipe 65 extends and to which the pipe 6 is connected at 70.

The pipes 65,66 are dimensioned and arranged so that the level of liquid therein when the apparatus is initially set up does not reach the level of the lower end of pipe 66 and is below the level of the inlet 38 to the atomising head, and to ensure that when the apparatus is stopped during use, the equilibrium level of liquid therein is below the level of the lower end of pipe 66 and below the level of the inlet 38.

In the embodiment shown in Figures 8 and 9, the vent 34 in the holder 32 is connected to a reservoir in the form of an annular chamber 46 which is designed to accommodate not only the liquid which flows back into the container when operation of the apparatus is continued but also the liquid that flows out of the container 30 when the apparatus is set up.

Of course the container 46 is dimensioned to ensure that the level of liquid therein does not reach the level of the inlet 38 in the atomising head when the apparatus is set up and to ensure that the equilibrium level of liquid therein, when the apparatus is in the condition of Figure 5, is such that the reduced atmospheric pressure created in the atomising head when it is in operation is sufficient to draw the liquid up pipe 6 and into the atomising head. As shown, the chamber 46 is made integral with the holder 32 but may, of course, be provided separately.

The atomising head 1 may be of any suitable form of the type which creates a reduced pressure in the region of the liquid inlet 38. As shown in Figure 9, the atomising head 1 comprises plurality of discs 50, 51, 52 and 53 which are connected to, and for rotation with, a hub 54 connected to a central shaft 55 driven by the motor. The liquid inlet 38 is positioned adjacent a spacer collar 57 and liquid flows therefrom between the discs and exits radially thereof from the gaps between the discs.The discs are arranged to create the required level of subatmospheric pressure in the region of the inlet 38 and, as shown, the axially rearward disc 53 has a radiaily inward flange 56 which is arranged to terminate immediately adjacent the fixed support for the head to rearwardly close the region of reduced pressure to maintain this reduced pressure as low as possible.

It will be appreciated that, in making the apparatus adjustable about axis 16, axis 16 must be positioned so as to minimise the relative variations which occur in the various levels A, B, C, D and E and it is for this reason that the axis 16 is generally vertically aligned with the inlet 33, vent 34 and outlet 38. The precise spacing of the various levels will of course depend on the degree of reduction of pressure at the inlet 38 created by operation of the atomising head and the specific gravity of the liquid to be sprayed thereby.

Claims (11)

1. A spraying apparatus comprising an atomising head having an inlet for liquid to be atomised thereby, the atomising head being such that in operation a zone of reduced pressure is created in the region of the inlet, a closed container for liquid having an outlet and a vent in the region of the lower part thereof, the container outlet being connected to the atomising head inlet by a duct and the vent being in use in communication with the atmosphere, the container being arranged relative to the atomising head such that the atomising head inlet is above the level of the container outlet so that, when the apparatus is not in use, the liquid in the container is in equilibrium with the level of liquid in the duct intermediate the atomising head inlet and the container outlet, the reduced pressure created in the atomising head in use being sufficient to draw liquid from the duct to the atomising head inlet.

2. Apparatus as claimed in Claim 1, wherein the vent communicates with the reservoir for receiving liquid when the apparatus is not in use.

3. Apparatus as claimed in Claim 2, wherein the reservoir is provided by a pipe connected by its lower end to the vent and in communication with the atmosphere.

4. Apparatus as claimed in Claim 3, wherein the pipe has a lateral connection to an auxiliary reservoir, the lateral connection forming a weir.

5. Apparatus as claimed in Claim 3, wherein the upper end of the pipe is closed and the pipe is connected to the atmosphere by an opening intermediate the ends thereof, the upper end of the pipe providing a chamber for receiving liquid when the apparatus is inverted.

6. Apparatus as claimed in Claim 5, wherein the opening is provided by a second pipe extending into the first mentioned pipe through the closed end thereof and open to the atmosphere, the chamber being annular and defined between the first mentioned and the second pipes.

7. Apparatus as claimed in Claim 2, wherein the reservoir is provided at least in part by a chamber at least in part extending around the lower part of the container and in communication with the atmosphere.

8. Apparatus as claimed in any one of the preceding claims, including mounting means for mounting the apparatus on a structure, the container and reservoir being fixed relative to the atomising head which is pivotable on the mounting means between an operative position for use and a position in which the container is inverted, the container being removable from the apparatus.

9. Apparatus as claimed in Claim 8, wherein the atomising head is adjustable relative to the mounting means about a horizontal axis arranged so as to minimise variations in the levels of liquid in the apparatus in operation and when not in operation.

10. Spraying apparatus substantially as herein described with reference to Figures 1 to 6 and 8 to 10 ofthe accompanying drawings.

11. Spraying apparatus substantially as herein described with reference to Figure 7 of the accompanying drawings.