WO2006095163A1

WO2006095163A1 - Nozzle comprising a flow control apparatus

Info

Publication number: WO2006095163A1
Application number: PCT/GB2006/000818
Authority: WO
Inventors: Kevin Laidler; Keith Laidler
Original assignee: Incro Limited
Priority date: 2005-03-08
Filing date: 2006-03-07
Publication date: 2006-09-14

Abstract

A nozzle has a flow control apparatus for controlling the flow of fluid through the nozzle passage (16). The apparatus includes a first portion of the fluid flow passage (46; 26) with at least one orifice (44) though which fluid flowing through the passage may exit the first passage portion. The apparatus also includes a flow control element (34) located in the first passage portion. The element is movable in response to the flow of fluid through the passage to bring a face (38) of the element into abutment or very close proximity with a corresponding face (42) of the first passage portion so as to restrict the flow of fluid through the at least one orifice. The arrangement is such that the fluid flowing through the passage is constrained to flow between the corresponding faces of the control element (34) and the first passage portion to reach the at least one orifice. The flow control apparatus may be used to provide a substantially constant rate of flow through the nozzle over a range of fluid pressures and/or to provide a self-cleaning orifice.

Description

Nozzle comprising a Flow Control Apparatus

The present invention relates to nozzle comprising apparatus for controlling the flow of a fluid through the nozzle.

Nozzles are often used to provide a means of generating sprays of various fluids. In particular, nozzles are commonly fitted to the outlet valves of aerosol cans to provide a means by which the fluid stored in the container can be dispensed in the form of a spray or mist. A large number of commercial products are presented to consumers in this form, including, for example, antiperspirant sprays, de-odorant sprays, perfumes, air fresheners, antiseptics, paints, insecticides, polish, hair care products, pharmaceuticals, water and lubricants. In addition, pump or trigger-actuated nozzle arrangements, i.e. arrangements where the release of fluid from a non-pressurised container is actuated by the operation of a manually operable pump or trigger that forms an integral part of the arrangement, are also frequently used to generate a spray or mist of certain fluid products. Examples of products that typically incorporate pump or trigger nozzle devices include various lotions, insecticides, as well as various garden and household sprays.

The flow of fluid through a device, such as a nozzle, is usually governed by the size of a hole, opening or similar restriction somewhere in the flow path, with the flow being proportional to both the size of the hole and the pressure of the fluid. The hole may be a final outlet of the device or it might be provided internally within the device between one part of a flow passage and another. In many applications, it is desirable to maintain a flow that is as constant as possible despite variations in the pressure of the fluid through the nozzle.

One example of this includes nozzles fitted to aerosol cans where the flow reduces as the can empties, adversely affecting the performance of the product. This is true regardless of the type of propellant used but is a particular problem where the propellant is air or gas where the flow may be reduced by two thirds over the life of the can.

Another example is an industrial wash application in a factory where there may be several manifolds of spray nozzles cleaning a product with water. Often the same supply will feed a number of machines and it is common for the water pressure to vary. When the pressure is high, too much water will be used and will result in water being wasted and when it is too low, the product may not be properly cleaned. Similarly, machines such as spray etchers or developers in the printed circuit board industry have many manifolds of nozzles spraying liquors like etchants where the consistency of spray from each nozzle is vital. But pressure variations across the manifolds result in some nozzles having a higher pressure than others and hence delivering more liquor which in turn results in more etching on the boards in some places compared to others. Even the pressure of the mains water supply to homes and industry varies considerably during the day and this means that the flow throughout the building is inconsistent.

It is an object of the present invention to provide nozzle having a flow control apparatus that can help provide a more constant rate of flow of fluid through the nozzle over a range of fluid pressures.

In a nozzle, a spray is generated when a fluid is caused to flow through the nozzle arrangement under pressure. To achieve this effect, the nozzle arrangement is configured to cause the fluid stream passing through the nozzle to break up or "atomise" into numerous droplets, which are then ejected through an outlet of the arrangement in the form of a spray or mist.

The optimum size of the droplets required in a particular spray depends primarily on the particular product concerned and the application for which it is intended. For example, a pharmaceutical spray that contains a drug intended to be inhaled by a patient (e.g. an asthmatic patient) usually requires very small droplets, which can penetrate deep into the lungs. In contrast, a polish spray preferably comprises spray droplets with larger diameters to promote the impaction of the aerosol droplets on the surface that is to be polished and, particularly if the spray is toxic, to reduce the extent of inhalation.

The size of the aerosol droplets produced by conventional nozzle arrangements is dictated by a number of factors, including the dimensions of the outlet orifice and the pressure with which the fluid is forced through the nozzle. However, problems can arise if it is desired to produce a spray that comprises small droplets with narrow droplet size distributions, particularly at low pressures. The use of low pressures for generating sprays is becoming increasingly desirable because it enables low pressure nozzle devices, such as the manually-operable pump or trigger sprays, to be used instead of more expensive pressurised containers and, in the case of the pressurised fluid- filled containers, it enables the quantity of propellant present in the spray to be reduced, or alternative propellants which typically produce lower pressures (e.g. compressed gas) to be used. The desire to reduce the level of propellant used in aerosol canisters is a topical issue at the moment and is likely to become more important in the future due to legislation planned in certain countries, which proposes to impose restrictions on the amount of propellant that can be used in hand-held aerosol canisters. The reduction in the level of propellant causes a reduction in the pressure available to drive the fluid through the nozzle arrangement and also results in less propellant being present in the mixture to assist with the droplet break up.

A further problem with known pressurised aerosol canisters fitted with conventional nozzle arrangements is that the size of the aerosol droplets generated tends to increase during the lifetime of the aerosol canister, particularly towards the end of the canisters life as the pressure within the canister reduces as the propellant becomes gradually depleted. This reduction in pressure causes an observable increase in the size of the aerosol droplets generated and thus, the quality of the spray produced is compromised.

Accordingly, it is an object of the present invention to provide a nozzle having a flow control apparatus which helps in generally reducing the size of the droplets generated when compared with conventional nozzle devices, as well as reducing the droplet size distribution. In addition, it is an object of the present invention to provide nozzle having a flow control apparatus to enable small droplets of fluid to be generated at low pressures, i.e. when fluids containing reduced or depleted levels of propellant, or a relatively low-pressure propellant such as compressed gas, is used, or a low-pressure system is used, such as a pump- or trigger-actuated nozzle arrangement.

The problem of providing a high quality spray at low pressures is further exacerbated if the fluid concerned has a high viscosity because it becomes harder to atomise the fluid into sufficiently small droplets.

Accordingly, it is a further object of the present invention to provide a nozzle having a flow control apparatus that can be used so as to make the nozzle capable of generating a spray from a viscous fluid at low pressures.

A further problem associated with known nozzle arrangements is that certain products have a tendency to block or clog the spray orifices provided in the nozzle arrangement. International Patent Publication Numbers WO 01/89958 and WO 97/31841 both describe cleanable nozzle arrangements, which can be slit apart to expose the internal fluid flow passageway for cleaning. However, it is not practicable to clean the spray orifices after each individual use, which may be necessary with some products that are particularly prone to clogging the nozzle arrangement. As a consequence, the spray orifices present at the outlet of the nozzle arrangement or within the nozzle can become blocked or clogged with such products, which can adversely affect the performance of the nozzle arrangements and thus, the quality of the spray produced.

Hence, it is a further object of the present invention to provide nozzle having a flow control apparatus that reduces the occurrence of blockages at spray orifices.. In particular, it is an object of the present invention to provide a nozzle having a flow control apparatus which provides a self cleaning nozzle outlet.

In accordance with the invention, there is provided a nozzle comprising a fluid inlet, a fluid outlet and a fluid flow passage connecting the inlet and the outlet, the nozzle comprising flow control apparatus for controlling the flow of fluid through the passage, the flow control apparatus comprising a first portion of the fluid flow passage, at least one orifice though which fluid flowing through the passage may exit the first passage portion, and a flow control element located in the first passage portion and which is movable in response to the flow of fluid through the passage to bring a face of the element into abutment, or very close proximity, with a corresponding face of the first passage portion so as to restrict the flow of fluid through the at least one orifice, in which, in use, fluid flowing through the passage is constrained to flow between the corresponding faces of flow control element and the first passage portion to reach the at least one orifice.

Other features of the invention are to be found in the claims dependent on claim 1.

Several embodiments of the invention will now be described, by way of example only, with reference to the following drawings in which:

Figure 1 is a cross section through a nozzle showing two possible locations for a flow control apparatus in accordance with the invention; Figures 2 to 11 are schematic cross sectional views of a variety of different embodiments of flow control apparatus for use in a nozzle in accordance with the invention;

Figures 12 to 14 are schematic end elevations of a flow control element forming part of a flow control apparatus for use in a nozzle in accordance with the invention showing different groove formations;

Figures 15 to 27 are schematic views similar to those of Figures 2 to 14 illustrating further embodiments of flow control apparatus for use in a nozzle in accordance with the invention. Figure 1 shows a nozzle 10 having an inlet 12, an outlet 14 and a fluid flow passage 16 connecting the inlet to the outlet. The inlet comprises a first recess 18 for receiving the end of a dip tube or the stem of an outlet valve of an aerosol canister (not shown). The passage 16 comprises a first expansion chamber 20, a second expansion chamber 22 in which the inlet and outlet are off-set to provide a dog-leg, an inner orifice or flow restriction 24, and a further expansion chamber 26 adjacent the outlet orifice 14. The nozzle also includes two flow control apparatuses 30, 32 in accordance with the present invention.

In most applications, it is expected that only a single flow control apparatus will be incorporated into a flow passage of a nozzle to control the flow of one or more fluids through that passage. Nevertheless, in certain applications it may be desirable to use multiple flow control apparatuses either in series or in parallel. In Figure 1, two flow control apparatuses are shown in order to illustrate two possible locations for a flow control apparatus, one 30 adjacent a final outlet orifice and one 32 adjacent an internal orifice.

Each of the fluid flow control apparatus 30, 32 includes a fluid flow control element or shuttle 34 that is movable in the fluid flow passage under the influence of the fluid flowing through the passage. In the present embodiment, the fluid flow passage 16 is circular in cross section and flow control elements are in the form of discs or short rods each having a flat end face 38 that is arranged to contact, or at least face in very close proximity, a wall 42 of the passage in which there is an opening or orifice 44 defining an outlet. In the case of the fluid flow apparatus 30 in the final expansion chamber 26, the opening 44 forms the final outlet orifice 14 of the nozzle. However, in the case of the other fluid flow control apparatus 32, the opening 44 comprises the inner orifice 24 which defines an outlet from one portion 46 of the fluid flow passage 16 to a further portion 48 of the fluid flow passage 16.

Each flow control element 34 has a substantially flat face 38 that contacts, or is brought into very close proximity to, the wall 42 of the passage in which the opening 44 is formed when fluid flows though the passage 16 from the inlet 12 to the outlet 14. As shown in Figure 1, the outer diameter of each of the flow control elements 34 is greater than that of its respective opening 44 so that it completely covers the opening and overlaps with at least part of the wall surrounding the opening 44 when it is in contact or close proximity with the wall 42. However, by appropriate design and selection of materials, it can be arranged that the flow control element 34 does not form a perfect seal with the wall 42 such that fluid can pass between the flow control element 34 and the wall to enter and pass through the opening 44.

It will be appreciated that the higher the pressure of the fluid flowing through the passage 16, the greater the force with which the flow control element 34 is pushed towards the wall 42 of the passage. Thus, when the pressure of the fluid flowing through the passage 16 is high, the flow control element 34 will be pushed towards the wall 42 with a correspondingly high force forming a closer seal and offering a higher resistance to the flow of fluid through the opening 44. Conversely, if the pressure of the fluid flowing through the passage drops, the force pushing the flow control element 34 towards the wall 42 will be lower and the fluid will be able to pass between the flow control element and the wall more easily. It can, therefore, be arranged that, over a given range of pressure variation, the flow of fluid through the opening 44, and hence through the fluid flow passage 16, remains fairly constant or at least more so than would be the case without the flow control apparatus. Table I below shows the volumetric flow rate against pressure for three different opening sizes using a flow control apparatus in accordance with the invention in which the fluid is air.

Table I

It can be seen from table I that the volumetric flow rate for all three opening sizes remains unchanged for pressures in the range of 4 to 10 bars.

Movement of the flow control element 34 in a direction away from the wall 42 may be physically restricted by the use of a back stop such as projections 50. In the case of the flow control apparatus 30, the flow control element 34 is constrained to move within the final expansion chamber 26 but additional stop means could be provided to more closely limit the movement of the flow control element 34 if desired.

As discussed above, each flow control element 34 has a flat face 38 that is forced into contact with a correspondingly flat inner face of the wall 42 of the passage in which the respective opening 44 is provided The element 34 is sized so as to cover the opening 44 and some of the surrounding wall. Preferable, both the flow control element 34 and the wall 42 of the passage are made from a rigid material such as polypropylene or nylon plastic, metal or ceramic so that the two flat surfaces 38, 42 are not able to form a true seal even when biased together by the pressure of the fluid travelling through the passage. However, for applications that are required to operate at lower pressures, it may be appropriate to use softer materials as these can form a partial seal at the lower pressures.

To ensure that a complete seal is not formed between the flow control element 34 and the end wall 42, the surface of the wall and/or the face 38 of the flow control element may be textured or other means may be provided to space the flow control element from the wall by a very small amount. Alternatively, grooves may be formed in the surface of the wall and/or the face 38 of the flow control element along which the fluid can pass to reach the opening 44.

In certain embodiments, at least part of the face 38 of the flow control element 34 will contact the wall 42 whilst fluid is flowing through the passage 16 and orifice 44. However, in other embodiments, particularly where the faces of the element 38 and the wall 42 are smooth, the fluid flowing between the faces may force them apart by a very small amount. In most cases, the gap between the faces 38, 42 in use will be no more than 0.01mm but in certain circumstances the gap may be up to a maximum 0.3mm or, more rarely, up to a maximum of 0.6mm. It should be appreciated that the spacing between the faces in use is dependant on the pressure of the fluid flowing through the passage. Where the pressure of the fluid is high, the gap between the faces will be small so that the cross sectional area through which the fluid can flow is correspondingly small. If the pressure of the fluid flowing through the passage drops, the gap between the faces 38, 42 will increase so that the cross sectional area through which the fluid can flow to pass through the orifice 44 also increases. As the rate of flow of the fluid through the passage is dependent on the pressure of the fluid and the minimum cross sectional area through which it must pass, it can be arranged that any decrease in pressure of the fluid is at least partially balanced by an increase in the cross sectional area of the gap between the faces to maintain a generally constant flow rate.

The inner flow control apparatus 32 in Figure 1 acts like a multiple pre- throttle and produces a fine spray in the inner orifice 24 and the final expansion chamber 26. A number of semi-circular grooves (not shown) could be provided around the circumference of the flow control element 34 to create spray orifices for spraying into the inner orifice 24, however, these would normally be too small for the total flow so that some leakage between the flow control element 34 and the wall 44 would also occur.

In the present embodiment, the flow control element 34 is free to move away from the wall 42 and the opening 44 when the fluid stops flowing through the passage. This has the advantage of allowing any debris that may have built up around the flow control element 34 to be ejected through the opening 44 the next time the nozzle is used. Thus the flow control apparatus can be used to provide a self cleaning nozzle. This is particularly advantageous in applications that normally require very small openings in order to generate the required fluid flow rate and where such openings are vulnerable to becoming blocked. By use of a flow control apparatus in accordance with the invention, the size of the opening can be increased whilst ensuring that the fluid flow and fluid pressure characteristics are maintained in use. After use, the flow control element is free to move away from the wall leaving a larger opening through which any small debris is able to pass.

Although as described above the flow control element 34 is free to move relative to the wall under the influence of the fluid, in alternative embodiments (not shown) the flow control element 34 may be biased by a spring means to ensure that it moves away from the wall 42 when the device is not in use. Alternatively, the flow control element 34 could be biased by a spring means into contact with the wall 42 but with insufficient force to create a complete seal. This arrangement may help in stabilising flow across a wider range of fluid pressures.

The design of the flow control element 34 and/or the wall 42 can be varied to suit the particular requirements of the application. The key is to create an interaction between the inner face of the wall 42 and the face 38 of the flow control element 34 that allows fluid to pass into the opening 44 in a controlled way. Hence, the seal between the flow control element 34 and the wall 44 is partial and never complete in the pressure range required but increases in effectiveness with the pressure of the fluid so that the rate of flow of the fluid through the opening 44 remains generally constant within acceptable tolerances.

By varying the configuration of the flow control element 34 and the wall 42, different flow effects can be produced so that one arrangement might produce an acceptably constant flow over a first pressure range of say 4-10 bar upwards whilst another may produce an acceptably constant flow at a different pressure range of say 0.1- 4 bar. The design of the flow control apparatus may also be affected by the desired flow rate and the properties of the fluid. In practice, it is expected that the configuration of the- flow control apparatus will be adapted to meet the specific needs of the particular application, taking into consideration all the relevant factors including the desired pressure range, the desired flow rate and the properties of the fluid.

Figures 2 to 27B are schematic drawings that illustrate a number of possible configurations that can be used in a flow control apparatus for use in a nozzle in accordance with the invention. It will be appreciated that these drawings only show the flow control apparatus itself, or a part thereof, and that the flow control apparatus will be incorporated into a nozzle. It should also be appreciated that the, or each, opening 44 may be a final outlet opening of the nozzle or an internal opening between one portion of a flow passage and another.

As the flow control apparatus of the invention is adapted to deliver a fairly constant flow rate across a range of pressures, it is necessary to be able to adapt the design to deliver different flow rates across that range of pressures. Hence, if one configuration delivers a flow rate of 2 1/m for pressures of 2-10 bars, it will be necessary to change the configuration in order to deliver a flow rate of say 3 1/m over the same pressure range. The simplest way to achieve this is to vary the size of the opening 44 such that the larger the opening, the greater the flow rate. Alternatively, it is possible to provide multiple openings 44 in the wall 42 to provide a greater flow rate. Figures 2 and 3 illustrate flow control apparatus in which the size of the opening 44 is varied whilst Figure 4 illustrates the use of multiple openings.

Other factors that may influence the flow rate include the surface finish of the corresponding faces of the wall 42 and the element 38 and the materials from which the wall and/or flow control element are manufactured. Thus, a smooth surface finish will tend to reduce the flow rate compared with a rough or textured surface finish. Also, as discussed above, the use of harder materials for the wall 42 and/or the flow control element 34 will tend to increase the leakage between the flow control element and the wall and so will lead to a greater flow rate than would be achieved if softer materials are used.

Another way of controlling the flow rate through the apparatus is to alter the overlap or contact area betweenlhe flow control element 34 and the wall 42. The required overlap or contact area to achieve a desired flow rate depends on the size of the opening, the materials of the flow control element 34 and the wall 42, the surface finish of the surface 38 of the flow control element and the wall 42, the pressure range involved and the properties of the fluid. However, generally speaking, different overlaps permit different levels of leakage and these determine the flow rates. At higher pressures, over say 4 bar, the overlap can be reduced as the flow tends to be stable whereas at lower pressures the overlapping area may need to be larger. Figure 5 illustrates a flow control apparatus having a reduced overlap between the flow control element 34 and the end wall 42 compared with that of the flow control apparatus shown in Figure 2.

Although not shown in the accompanying drawings, an alternative method of reducing the overlap, whilst ensuring the shuttle remains stable in the passage, is to reduce the outer diameter of shuttle and provide a number of vanes which project outwardly to contact the side wall of the passage. A further alternative, also not shown, would be to use a shuttle which is square or triangular rather than circular.

A further design option as illustrated in Figure 6, is to provide a circular recess 52 in the face 38 of the flow control element 34 that contacts the wall 42. This reduces the contact area between the flow control element and the wall which tends to increase the flow rate. Furthermore, the recess 52 can be used as a swirl chamber to impart rotation into the fluid causing it to form a spray as it leaves the opening 44. To aid this effect, the fluid may be caused to spin around the fluid flow passage portion in which the flow control element is located so that when it enters the chamber 52 it is already spinning. This could be achieved by using a tangential input into the fluid flow passage portion or by using a known swirl device upstream from the flow control element. Alternatively, or in addition, curved veins (not shown) could be put inside and around part of the circular recess 52 or opening 44 to cause the fluid to spin and create a conical spray. If there is more than one opening 44 in the wall, several recesses 52 could be provided, each acting as a swirl chamber for a respective one of the openings. The recess 52 can be of any suitable shape. Figure 7 illustrates a flow control apparatus in which the fluid flow passage portion 53 and the flow control element 34 are conical or frusto- conical, tapering inwardly towards the wall 42. With this arrangement, a spiral formation (not shown) can be applied to the side walls of the passage portion or the side 35 of the flow control element 34 to cause the fluid to spin and create a conical spray through the opening 44. In an alternative embodiment (not shown) the end wall 42 may be omitted so that the fluid will pass between the conical side 35 of the flow control element 34 and the corresponding face of the side wall of the passage portion 53. The flow control element used in this embodiment can be of any suitable shape such as any of those shown in the accompanying drawings. A swirl arrangement may also be used to cause the fluid to rotate either before it reaches the flow control element, after the flow control element or around the flow control element. In certain applications, it may be advantageous to create a point or line seal between the side 35 of the flow control element and the conical side wall of the passage portion 53. This could be achieved, for example, by not tapering the side 35 of the flow control element 34. In a further alternative embodiment, a groove is provided around the side 35 of the flow control element with the front and rear edges both sealing against the conical wall 53. A first fluid can be arranged to enter the groove so as to cause the element 34 to rotate whilst a second fluid enters the fluid flow passage portion 53 upstream of the flow control element 34 at substantially the same pressure as the first fluid preventing the two fluids mixing around the edges of the flow control element 34. The second fluid can then be allowed to pass though the flow control element by means of a suitable passage which might, for example, pass through the centre of the element 34 or any other part thereof. In embodiments where the flow control element 34 engages a tapered wall of the chamber, the wall or the element 34 can be configured to be flexible enough to cause the element 34 to spring back away from the wall when the fluid pressure is released. Figure 8 shows an arrangement in which a conical recess 54 is formed in the face 38 of the flow control element 34 and a corresponding conical recess 56 is formed in the wall 42 of the fluid flow passage about the opening 44. This arrangement creates an expansion chamber 58 into which the fluid passes from between the flow control element and the wall. If the gap between the flow control element 34 and the wall 42 is small, the fluid will be sprayed into the expansion chamber. Where the wall has multiple openings 44, the face 38 of the flow control element and/or the wall 42 can have a corresponding number of recesses to provide an expansion chamber 58 for each opening. The openings 44 will usually be located centrally of their respective chambers. The expansion chamber(s) 58 can be of any suitable shape.

As shown in Figure 9, a post 60 may project from the flow control element 34 into the opening 44. If the gap between the post 60 and the side of the opening is small, the fluid will form a spray as it passes through the gap. A series of fine grooves could be provided around the inside of the opening 44 or on the surface of the post 60 that effectively create a number of semi-circular openings between the post and the opening 44 which would operate as multiple fine spray openings. The post 60 can project beyond the outer face of the 42 as shown or it could be flush with it or the post 60 could be shorter than the thickness of the wall so that it ends below the outer surface of the wall as shown in Figure 16. The free end of the post, the opening 44 and/or both the outer circumference of the post 60 and the opening 44 could be conical or frusto-conical. The shape and length of the post all affect the flow through the opening 44 and can be used to provide a conical spray, for example.

The post 60 could be hollow and/or made of very flexible material and be designed to fill or almost fill the opening 44 when there is no fluid flowing through the nozzle. When the nozzle is in use, the pressure of fluid will compress the post 60 to allow the fluid to flow through the opening. This arrangement can be used to prevent dripping from the nozzle after use. Whilst the face 38 of the flow control element 34 that contacts or faces the wall 42 and the wall 42 itself are often flat, they can be shaped in certain ways that ensure only a partial seal is formed and to vary the flow rate. Figure 10 illustrates a flow control apparatus in which the face 38 of the flow control element is curved. This can be useful in nozzle applications where the shape of the fluid control element and/or the wall can be used to vary the spray pattern and spray configuration.

Figure 11 illustrates a flow control apparatus in which the flow control element 34 is in the form of a flap, one end of which is connected to one of the walls of the passage. Preferably, the flap would normally adopt a position spaced from the end wall 42 when there is no flow, as shown in Figure 11, and be moved into contact or close proximity with the wall when the nozzle is in use and the pressurised fluid flows through the passage portion. However, the flap could be arranged to contact or lie close to the wall 42 at all times but be configured so that the partial seal formed between the flap and wall increases in effectiveness as a function of the pressure of the fluid to control the rate of flow. Any of the embodiments described herein can be provided in the form of a flap. However, this arrangement is most suited for use with a so called "split nozzles" which are produced in two parts that are assembled together to form the finished nozzle. In a split nozzle, the fluid flow passageway(s) and orifices are formed at the interface of the two parts by means of grooves and/or recesses formed in one or both of the parts. Typically, each of the two parts has an abutment surface which contacts a corresponding abutment surface on the other of the parts when they are assembled and the grooves and/or recess are formed in the abutment surface of at least one of the parts.

As discussed above, the surface finish of the flow control element 34 and/or the wall 42 can be modified to vary the flow rate and other flow characteristics. For example, a series of fine rods could project from the wall 42 or from the face 38 of the flow control element to ensure a minimum spacing is maintained and which could act as a filter. Alternatively, grooves could be formed in the wall 42 and/or in the face 38 of the flow control element that contacts the wall 42. The grooves would ensure that there was at least a minimum flow of fluid arid the grooves could be arranged to impart particular flow characteristics to the fluid such as causing the fluid to form a spray through the opening 44.

Figures 12 to 14 illustrate some examples of groove arrangements that might be used. These drawings show the face 38 of the flow control element 34 with the inner circle 62 being indicative of the position of the opening 44 in the wall 42. It should be understood that the grooves could be formed in the wall 42 rather than in the end face 38 of the flow control element 34 if desired.

In Figure 12, a circular groove 64 having a diameter larger than that of the opening 44 has a number of radial spoke like grooves 66 leading towards the centre of the flow control element 34 and the opening 44. With this arrangement, the fluid would collect in the circular groove 64 and then travel along the radial grooves 66 towards their inner ends where it would enter the opening 44 as a series of fine sprays. If the end face 38 of the flow control element and the wall 42 are conical, the fluid would be sprayed outwards and could be directed so that the various sprays hit each other or miss each other as required.

In Figure 13, an outer circular groove 64 is connected to a central recess

68 by two straight radial grooves 70, 72 which are of different sizes. The radial grooves 70, 72 are arranged to enter the central recess non-tangentially on different sides of the opening 44 so as to cause the fluid to rotate within the central recess 68.

In Figure 14, an outer circular groove 64 is connected to a central recess 68 by two curved radial grooves 74,^" 76 which direct the fluid into the central recess tangentially in the manner of a swirl chamber to case the fluid to spin in the recess.

Any suitable groove pattern can be applied to the surface of the flow control element 34 and/or the wall 42. Where the grooves are formed in the wall, the flow control element 34 would normally cover all the grooves so that the fluid had to pass between the element 34 and the wall 42 to reach the grooves. However, in applications where control of the flow rate is not essential, the flow control element may only cover part of the grooves so that the apparatus acts simply as a self cleanable/ self cleaning nozzle.

Figures 15A and 15B illustrate a flow control apparatus that is adapted to also act as a one way valve. This is achieved by arranging for the flow control element to form a fluid seal with the stop means 78 that restricts its movement away from the wall 42. When the device is operated in normal use, movement of the fluid in the forward direction from the inlet to the outlet, as indicated by arrow A in Figure 15 A, moves the flow control element 34 toward or into contact with the wall 42 of the passage where it acts as described above in relation to the previous embodiments. However, if the direction of flow is reversed, as indicated by arrow B in Figure 15B, the flow control element is moved away from the wall 42 into contact with the stop means 78 with which it seals, serving to close the passage and preventing further reverse flow of the fluid. Suitable shaping of the stop means 78 and the flow control element 34 will be required to ensure that a proper seal is formed.

If desired, the flow control element 34 may be biased into contact with the stop means 78 by a spring or the like (not shown) so that it operates as a pre-compression valve only opening to allow fluid flow once the pressure of the fluid is sufficient to overcome the spring bias. In one embodiment, the flow control element 34 can be adapted to act as a spring itself. For example, the element 34 can be manufactured from a resilient material and dished towards the end wall 42 so that it is flattened against the wall 42 by the pressure of the fluid in normal use. When the pressure is reduced, the flow control element 34 will reform and spring away from the wall 42 so as to contact the stop means 78. If the distance between the wall 42 and the stop means 78 is small, the flow control element 34 would have to be squashed by the fluid to move away from the stop means 78, requiring a minimum pressure in the fluid to do so.

A similar pre-compression effect could be achieved by ensuring that there is a strong sealing bond between the flow control element 34 and the stop means 78. For example, if the seal means 78 had a plain hole and the flow control element 34 had a conical end that engaged in the hole, the bond between the flow control element 34 and the seal means 78 would be strong so that a certain level of pressure in the fluid would be required to overcome the inertia.

Figures 16 to 27B illustrate schematically a number of further embodiments of a flow control apparatus in accordance with the invention.

The embodiment shown in Figure 16 is similar to that described above in relation to Figure 9, except that the post 60 in this embodiment is shorter and does not project beyond the outer face of the wall 42.

The embodiment shown in Figure 17A is also similar to that shown in Figure 9 but has an even shorter post 60. In addition, the embodiment in Figure

17A includes a V shaped grooved 80 formed in the outer surface of the wall 42.

The groove 80 can be seen more clearly in Figure 17B which shows an end view of the wall 42. When the apparatus is in use, the fluid, typically a liquid, flows through the orifice 44 and travels along the V shaped groove forming a fan shaped spray of droplets. A variety of different groove formations can be provided in the outer surface of the wall 42 to affect the spray pattern produced by the nozzle. The groove could be U shaped, for example. This arrangement has the advantage over conventional fan nozzles that it is self cleaning. Figures 18A and 18B, illustrate an alternative groove arrangement 81 which produces a square shaped cone of droplets. This arrangement comprises two V shaped grooves 8 IA, 8 IB which extend at right angles to one another and meet at the opening 44 to form a cross. These embodiments are particularly applicable where the opening 44 is a final outlet orifice of the nozzle.

In the embodiment shown in Figures 19A and 19B, the flow control element 34 has a central post 60 which extends into the opening 44 in the wall 42 but is also provided with a swirl inducing formation 82 on the face 38 of the element which abuts the wall 42. The swirl formation 82 includes two curved grooves which direct fluid into a circular recess 84 surrounding the post 60 so that it spins about the post forming a cone spray of droplets. The height of the post 60 in the hole dictates the shape of the cone. Unlike a conventional swirl arrangement, the control element 34 is able to move relative to the wall 42 to control the flow of fluid through the opening. The nozzle in this embodiment is self cleaning and enables very fine droplets to be created because the gap between the control element 34 and the wall 34 is much finer than could be created with conventional moulding techniques used to produce known swirl arrangements in nozzles. The swirl forming grooves could be formed on the inner face of the wall 42 rather than on the flow control element 34 or on both. Groove formations such as those shown in Figures 17 and 18 could be provided on the outer surface of the wall 42 to further control the spray pattern produced.

The embodiment shown in Figures 2OA and 20B illustrate how the control element 34 can be modified to form an integral spring for self cleaning nozzles. The main body portion 86 of the control element has a dish shape with a concave face 38 which opposes the inner face of the wall 42 with the opening 44. As shown in Figure 20B₅ the main body portion can be compressed against the wall 42 by the pressure of the fluid flowing through the passage 53 so as to act as a flow control device in the manner previously described. When the flow of fluid stops, the main body portion 86 will resume its dished shape, as shown in Figure 2OA, so that any foreign matter trapped between the flow control element 34 and the wall 42 is released. The flow control element 34 may have a central post 60 which projects into the opening 44 as shown or this may be omitted. The flow control element 43, or at least part of the dish shaped main body portion 86 may be made of a flexible, resilient material so that the spring effect is retained for longer than would be the case with a generally rigid material. As described above, this conical disc arrangement can be used in conjunction with stop means to create a one-way flow valve or a pre- compression valve means It should be appreciated that any of the various features shown in the embodiments described herein can be combined in any suitable way to produce a desired flow control nozzle arrangement. For example, Figure 21 illustrates an embodiment which combines the features of the dished control element 34 as described above in relation to Figures 2OA and 2OB and the V shaped groove formation 80 as described above in relation to Figures 17A and 17B. Similarly, Figures 22A and 22B illustrate a flow control apparatus which combines a dished shaped flow control element 34 with a cross shaped groove formation 81 in the outer surface of the wall 42. Figures 23A and 23B illustrate an embodiment having a dish shaped flow control element 34 with a swirl feature 82, similar to that described above in relation to Figures 19A and 19B, formed on the face 38 of the element which abuts the wall 42.

As previously mentioned, the flow control element need not have a flat face 38 for contact/proximity with the wall 42. Figures 24, 25 and 26 illustrate embodiments in which the control element has a tapered face 38 which contacts or lies in close proximity with the wall 42 in use. In the embodiment shown in Figure 24, the end wall 42 of the passage is flat so that the tapered wall 38 of the control element contacts or lies in close proximity with the wall 42 along a line at the edge of the opening. In the Figure 25 embodiment, the wall 42 has a corresponding taper 86 which cooperates with the tapered face 38 of the flow control element. Figures 26A and 26B illustrate an embodiment similar to that of Figure 25 except that a swirl arrangement 82, similar to that described above in relation to Figures 19A and 19B, is formed on the tapered surface 38 of the flow control element. The swirl inducing grooves 82 can best be seen in Figure 26B which is an end elevation from above of the flow control element 34.

Figures 27A and 27B illustrate an embodiment in which the flow control element has grooves 90 formed in the surface 38 which contacts the wall 42. Figure 27B is an end elevation of the flow control element 34 which has a central recess 92 surrounded by an annular portion 94 which abuts the wall 42. The grooves 90 extend across the annular portion on two sides so that the fluid can pass through the grooves into the central recess and pass out though the opening 44. The control element 34 also has a post 60 which projects from the centre of the recess into the opening 44 in the wall 42. The control element may be made of a flexible material so that as the pressure biasing the element 34 into contact will the wall increases, the grooves 90 are partially closed to resist the flow. The arrangement can be used to control the flow rate of fluid through the opening as the pressure varies since the minimum cross sectional area through which the fluid flows is varied as a function of the pressure of the fluid. Hence at higher fluid pressures the minimum cross sectional area through which the fluid flows will be smaller than at lower fluid pressures. In an alternative arrangement, the grooves could be formed on the inner face of the wall 42 so that the flexible material of the flow control element is pushed into the grooves by the pressure of the fluid to partially fill the grooves and so regulate the flow through the opening. The central recess could be reduced in size or omitted altogether so that the grooves 90 are formed in a flat face 38 of the flow control element so long as they are in fluid connection with the opening 44 when in use.

The fluid flow passage portion 53 or chamber in which the flow control element 34 is located can be of any suitable shape and especially could be any of the shapes disclosed in the applicant's co-pending International patent application published as WO 2005/005055, the entire content of which is hereby incorporated by reference. Thus the shape of any of the fluid flow passage portions or chambers in any of the embodiments described above can be modified in accordance with the principles discussed in WO 2005/005055. Similarly, where a recess 52 or expansion chamber 58 is provided between the flow control element 34 and the wall 42, the recess or chamber can also be of any suitable shape including those disclosed in WO 2005/005055.

Fluid may be directed into the fluid flow passage portion or chamber in which the flow control element 34 is located in any suitable manner including any of the arrangements disclosed in the applicant's co-pending International patent application published as WO 2005/005053, the content of which is also hereby incorporated in its entirety by reference and any of the embodiments described herein can be modified accordingly.

Although the flow control apparatus of the invention is principally intend to provide for a stable flow rate through a device over a given pressure range, its use is not limited to applications requiring a stable flow rate. As already discussed above, the flow control apparatus can be used to provide a self-cleaning opening in a nozzle. This is because a larger than normal opening 44 is required for the same flow rate which helps to prevent blockages. In such applications, the seal between the flow control element 34 and the wall 42 can be made very poor so that the fluid flow still increases with pressure.

The flow control apparatus of the invention can also be used to provide a fine filter where the filtrate forms around the circumference of the flow control element 34 and downstream of it. The filtrate could be allowed to leave at very low pressure with the fluid driving the filtrate under the flow control element or it could be backwashed or sucked out after use. In embodiments where the flow control element is a shuttle, a rear end of the shuttle, which is distal from the corresponding face of the passage portion, may be provided with a conical fan having an outer edge which contacts the side wall of the passage portion. A number of fine holes or slits can be provided in the fan through which the fluid flows, the holes or slits being sized to prevent any foreign matter large enough to block the nozzle passage and orifices from passing through.

In applications such as nozzles for aerosols or hand pumps or triggers, the flow control element could be pushed back through the opening to allow cleaning when next used. Where, as shown in Figure 9, the flow control element 34 has a post projecting into an opening 42 which forms an outlet nozzle of the device, the post could be pushed inwardly to move the flow control element. Alternatively, a pin or the like could be inserted through the opening to move the flow control element 34. In a different embodiment, the device could be put into water or a cleaner (e.g. paint stripper) and shaken so the liquor pushes the shuttle backwards and forwards driving any blocking material outside. A particularly advantageous filter arrangement can be provided if the wall 42 against which the flow element abuts is provided in the form of a mesh.

The flow control apparatus of the invention has many applications and can be used in almost any nozzle where there is a requirement for controlling the flow rate, to provide self-cleaning, filtration or to generate sprays and can be used with any fluid or combinations of fluids regardless of their viscosity and can be adapted to work at all pressures both high and low. For example, in addition to the applications discussed above, nozzles incorporating flow control apparatus in accordance with the invention can be used as self-cleaning inkjet printer head nozzles or as washer jet nozzles for vehicle headlamps or windscreens.

The flow control apparatus of the invention can be used in any type of nozzle including nozzles that form sprays in the form of fans, full cones and hollow cones. When used with aerosols, pumps or triggers, the flow control apparatus could be used to control the gas, liquor or both in the nozzle.

In applications where two or more fluids are mixed together in a nozzle, flow control apparatus could be used to keep the flow of one or more of the fluids constant. For example, certain nozzles are arranged to mix a gas such as air with liquor and it is often important to maintain the same ratio of air to liquor to achieve the desired droplet distribution in the spray. One example is an aerosol where the pressure drop for both the gas and the liquor is the same. However, since gas flows much faster than liquor through an opening, the flow of gas through the nozzle reduces more than the flow of liquor during the life of the can so that the ratio of gas to liquor will reduce. In these circumstances, flow control apparatus could be used to maintain a constant flow rate for one or both of the gas and the liquor so as to maintain a constant ratio. In certain applications, it is desirable to use a lower ratio of gas to liquor at higher pressures in order to conserve the gas. In this case, a flow control apparatus in accordance with the invention can be used to maintain a constant flow of gas whilst the flow of the liquor is allowed to increase at higher pressure as in a conventional nozzle.

It is also possible to design the flow control apparatus to allow only a gas to pass through whilst preventing, or at least minimising, the passage of a liquid through the apparatus. This can be achieved by configuring the apparatus so that the flow control element 34 creates a close seal with the wall 42 through which only a gas can pass. In this arrangement, the flow control element 34 and/or the wall 42 may be made of, or covered by, a flexible material like rubber that forms good seal. In this arrangement, the wall 42 against which the flow control element 34 abuts may be in the form of a fine mesh that could become the equivalent of a membrane. It is a particular advantage of the present invention that the nozzle and flow control apparatus can be manufactured from plasties or polymeric materials using injection moulding techniques and is, therefore, simply and relatively cheap to manufacture. Whereas the invention has been described in relation to what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed arrangements but rather is intended to cover various modifications and equivalent constructions included within the spirit and scope of the invention. For example, it should be appreciated that any of the features shown in any of the embodiments described can be combined with any of the features shown in any of the other embodiments in any suitable manner. In particular, it should be noted that in any of the embodiments described, the fluid can be arranged to spin before, after or around the flow control element 34 in any combination and in any way. This spinning helps control of the droplet distribution of the nozzle and in pump and in compressed gas applications particularly, aids the spray atomisation. Furthermore, the flow control element 34 may be manufactured from a combination of materials to provide the required properties. For example, the element may be manufactured from two or more different materials using bi-injection moulding techniques. Thus, the flow control element could be manufactured to comprise a rigid core with a flexible outer portion to form a seal. In addition, two or more flow control elements could be used in series in the same fluid flow passage portion so that they push against each other or with one going inside a recess or opening formed in or through another element 34. This arrangement could be configured so that one of the flow control elements controls the flow of a first fluid whilst another controls the flow of a second fluid.

Claims

1. A nozzle comprising a fluid inlet through which a fluid may enter the nozzle, a fluid outlet through which a fluid may exit the nozzle as an atomised spray and a fluid flow passage connecting the inlet and the outlet, the nozzle further comprising flow control apparatus for controlling the flow of fluid through the passage, the flow control apparatus comprising a first portion of the fluid flow passage, at least one orifice though which fluid flowing through the passage may exit the first passage portion, and a flow control element located in the first passage portion and which is movable in response to the flow of fluid through the passage to bring a face of the element into abutment, or very close proximity, with a corresponding face of the first passage portion so as to restrict the flow of fluid through the at least one orifice, in which, in use, fluid flowing through the passage is constrained to flow between the corresponding faces of flow control element and the first passage portion to reach the at least one orifice.

2. A nozzle as claimed in claim 1, in which the flow control apparatus is configured such that, in use, the corresponding faces of the flow control element and the first passage portion are spaced by a maximum of

0.6mm by the fluid flowing between them.

3. A nozzle as claimed in claim 1 or claim 2, in which the flow control apparatus is configured such that, in use, the corresponding faces of the flow control element and the first passage portion are spaced by a maximum of 0.3mm by the fluid flowing between them.

4. A nozzle as claimed in any one of claims 1 to 3, in which the flow control apparatus is configured such that, in use, the corresponding faces of the flow control element and the first passage portion are spaced by a maximum of 0.01mm by the fluid flowing between them.

5. A nozzle as claimed in any one of claims 1 to 4, in which the flow control element and the first passage portion are configured such that, in use, the available cross sectional area between the corresponding faces of the flow control element and the first fluid passage portion through which the fluid is constrained to flow to reach the at least one orifice varies in dependence on the pressure of the fluid acting on flow control element.

6. A nozzle as claimed in claim 5, in which the flow control element and the first passage portion are configured such that, in use, the rate of flow of fluid through the at least one orifice remains substantially constant over a range of fluid pressures.

7. A nozzle as claimed in any one of the preceding claims, in which the ^' flow control element and the first passage portion are configured such that the corresponding faces do not form a perfect seal for the fluid at normal operating pressures.

8. A nozzle as claimed in claim 7, in which the corresponding faces of the flow control element and the first fluid passage portion both comprise rigid materials such that a perfect seal is not formed between the faces at normal operating pressures.

9. A nozzle as claimed in claim 7 or claim 8, in which at least one of the corresponding faces is rough or textured or is provided one or more formations to ensure that a perfect seal is not formed between them at normal operating pressures.

10. A nozzle as claimed in claim 7 or claim 8, in which one or more grooves or recesses are provided in at least one of the corresponding faces through which the fluid can flow to reach the at least one orifice.

11. A nozzle as claimed in claim 10, in which the flow control element and the first fluid passage portion are configured such that, in use, the minimum cross sectional area of the at least one groove or recess varies in dependence on the pressure of the fluid acting on the flow control element.

12. A nozzle as claimed in claim 11, in which the flow control element comprises a flexible material such that the at least one groove or recess is compressed, in use, by the pressure of the fluid acting on the flow control element to hold the corresponding faces in contact.

13. A nozzle as claimed in claim 11 or claim 12, in which the at least one groove or recess is/are configured to cause the fluid to spin about an axis of the at least one orifice prior to the fluid entering the at least one orifice in use.

14. A nozzle as claimed in ^"any one of the ^"preceding claims, in which the" first fluid passage portion comprises a wall at a downstream end of the portion and the at least one orifice extends through the wall.

15. A nozzle as claimed in claim 14, in which an inner face of the wall comprises the corresponding face of the first fluid passage portion.

16. A nozzle as claimed in claim 15, in which the face of the flow control element overlaps the at least one orifice and at least part of the face of the wall completely surrounding the at least one orifice.

17. A nozzle as claimed in claim 15 or claim 16, in which the face of the flow control element is a downstream end face of the flow control element.

18. A nozzle as claimed in claim 17, in which at least one recess is formed in the downstream end face of the flow control element, the, or each, recess being arranged to align with the, or a respective one of, the at least one orifice when the corresponding faces are brought into contact.

19. A nozzle as claimed in any one of the previous claims, in which the face on the flow control element is frusto-conical.

20. A nozzle as claimed in any one of the previous claims in which the corresponding face of the first fluid flow passage is frusto-conical.

21. A nozzle as claimed in any one of claims 1 to 18, in which the face on the flow control element is curved.

22. A nozzle as claimed in any one of claims 1 to 18 and 21, in which the corresponding face of the first fluid passage portion is curved.

23. A nozzle as claimed in any one of the preceding claims, in which the face of the flow control element and the corresponding face of the first fluid passage portion are configured to contact one another along a circle surrounding the at least one orifice.

24. A nozzle as claimed in any one of the previous claims, in which the flow control element comprises a post which projects into the at least one orifice, at least when the face on the flow control element is in abutment or very close proximity with the corresponding face of the first fluid passage face.

25.A nozzle as claimed in claim 24, in which the post is flexible and is configured to substantially close the orifice when the nozzle is not in use, the arrangement being such that, in use, when fluid flows through the passage, the pressure of fluid compresses the post to enable the fluid to pass through the orifice.

26. A nozzle as claimed in any one of the preceding claims, in which the flow control element comprises a flap attached at one end to a wall forming part of the first fluid passage portion for pivotal movement in response to a flow of fluid through the passage from a first position in which a face of the flap is spaced from the corresponding face of the first fluid passage portion and a second position in which the face of the flap is in abutment, or very close proximity, with the corresponding face of the first fluid passage portion.

27.A nozzle as claimed in any one of claims 1 to 25, in which the flow control element is a shuttle member located in the first fluid passage portion and movable in response to a flow of fluid through the passage from a first position in which a face of shuttle is spaced from the corresponding face of the first fluid passage portion and a second position in which the face of the shuttle is in abutment, or very close proximity, with the corresponding face of the first fluid passage portion.

28. A nozzle as claimed in claim 27, in which the shuttle comprises a disc or rod shaped member.

29. A nozzle as claimed in claim 27 or claim 28, in which the corresponding faces of the flow control element and the first fluid flow passage portion comprise a side surface of the shuttle and a side wall of the passage portion respectively.

30. A nozzle as claimed in any one of claims 27 to 29, in which stop means are provided to limit movement of the shuttle away from the corresponding face of the first fluid passage portion.

31. A nozzle as claimed in claim 30, in which the shuttle is adapted to form a seal with the stop means to prevent a reverse flow of fluid through the passage.

32. A nozzle as claimed in any one of claims 27 to 31, in which the nozzle comprises means to bias the shuttle towards the corresponding face of the first fluid flow passage portion.

33. A nozzle as claimed in any one of claims 27 to 31, in which the nozzle comprises means to bias the shuttle away from the corresponding face of the first fluid flow passage portion.

34. A nozzle as claimed in claims 32 or claim 33, in which the bias means is an integral part of the shuttle.

35.A nozzle as claimed claim 34, in which the shuttle comprises a disc having a concave face which opposes the corresponding face of the first fluid passage portion, the flow control element being compressible so that, in use, the pressure of the fluid flowing through the passage tends to flatten the concave face into abutment or close proximity with the corresponding face of the first fluid passage portion, the disc being restored to its concave condition when there is no fluid flowing through the passage.

36. A nozzle as claimed in claim 35, in which the disc is resiliently biased to its concave condition.

37.A nozzle as claimed in any one of the previous claims, in which the orifice is an internal orifice which leads from the first portion of the fluid passage into a further portion of the fluid passage.

38. A nozzle as claimed in any one of claims 1 to 36, in which the at least one orifice is the fluid outlet of the nozzle.

39. A nozzle as claimed in any one of the previous claims, in which one or more grooves are formed in an external face of the nozzle and which intersect the outlet orifice.

40. A nozzle as claimed in any one of the preceding claims in which there is more than one orifice through which fluid flowing through the passage may exit the first fluid passage portion.

41. A nozzle as claimed in any one of the previous claims, the nozzle having a first fluid inlet for a first fluid and a second fluid inlet for a second fluid, the fluid passage being configured such that the first and second fluids are mixed in the nozzle prior to exiting the nozzle outlet, in which the flow control apparatus is arranged to control the rate of flow of one of the first and second fluids before the two fluids are mixed.

42.A nozzle as claimed in claim 41, in which a separate flow control apparatus is used to control the rate of flow of each of the fluids through the nozzle prior to them being mixed.

43. A nozzle as claimed in any on of the previous claims, in which the flow control apparatus as acts as a filter.

44. A nozzle as claimed in any one of the previous claims, in which the flow control apparatus is self-cleaning.