WO2008047205A2

WO2008047205A2 - Spray masks and line markers

Info

Publication number: WO2008047205A2
Application number: PCT/IB2007/003075
Authority: WO
Inventors: Peter Viner; Rachael Elizabeth Roberts; Neil Kettlewell; Justin Kerslake; Jacey Moore
Original assignee: Illinois Tool Works, Inc.
Priority date: 2006-10-18
Filing date: 2007-10-15
Publication date: 2008-04-24
Also published as: EP2061934B1; TW200900557A; EP2061934A2; DK2061934T3; WO2008047205A3; GB0620727D0; GB0712964D0

Abstract

A line-marking apparatus, comprises a pair of primary wheels 58, 60; a pair of stabilizer wheels 106 each attached to and separately moveable with respect to the apparatus between laterally extended and closed positions; a mask 10 comprising an edge 22, 24 for defining the shape of marking fluid when sprayed on a surface; a threaded shaft 64 by which the mask is adjustably mounted in the apparatus; ducting 72 and battery-powered air impellers 74 mounted at a hub region of the primary wheel to provide an air flow at said shape-defining edge, which air-flow is arranged to direct sprayed marking fluid material from the shape- defining edge and within the marking fluid sprayed on the surface; a holder 41 in which an aerosol canister 108 is movably mountable, spring means 123 operative between the aerosol canister and the holder, the spring means being biased to complement the action of the aerosol outlet valve spring; and an outlet valve opening mechanism 120, 124 acting with mechanical advantage on the aerosol canister in opposition to the spring means. The holder 41 may be set at different heights by a button 52 selectively engageable in one of a series of vertically spaced apertures.

Description

SPRAYMASKSAND LINEMARKERS

Introduction

This invention relates to masks for defining the shape of marking fluid to be sprayed onto a surface. It primarily, but not exclusively, relates to apparatus for spraying lines onto surfaces, such as roads, car parks, factory and gymnasia floors, sports courts and playing areas, play grounds and sports fields. The invention further relates to wheeled line-marking apparatus and to elements thereof, including an aerosol operating device and stabilising and line width adjustment arrangements.

Background

Known spraying or line-marking apparatus comprise a conventional aerosol of line-marking fluid, absent a dip tube, mounted inverted on a wheeled carriage so that, when the aerosol nozzle is triggered open, marking fluid is sprayed downwardly as a line onto the surface over which the apparatus is being wheeled.

One problem associated with such apparatus is that the sprayed line can lack clear edge definition because of the pattern and distribution of marking fluid as it is sprayed. Typically, this has been controlled by some form of mask or shield to limit sideways spraying of marking fluid. However, such masks or shields accumulate "drips" of sprayed marking fluid which can subsequently fall clear of and outside the sprayed line.

Another problem associated with such apparatus is a lack of lateral stability. The simplest line-marking apparatus comprise a pair of wheels, between which line-marking fluid is sprayed. The wheels set the line width and are thus close together and lack lateral stability; permitting the carriage to "rock" as it is wheeled along, resulting in a sinuous line. A solution to this problem has been to provide fixed or add-on rear stabilizer wheels; but these can limit how close to a wall or the like obstacle a line can be sprayed.

A further problem is that, usually, the aerosol is operated by locating the spray nozzle in a fixed mounting and then forcing the aerosol can bodily down against the mounting to open a spring-loaded nozzle valve. This can result in accidental aerosol discharge even by small downward forces inadvertently applied to the aerosol can.

Prior Art Document GB-A- 1456411 (Rocol Limited) discloses a line-marking applicator comprising a pressurised aerosol spray dispenser of marking fluid mounted to spray downwardly between the wheels of a two-wheeled carriage and a pair of shields each co-axially mounted on the inner side of one of the carriage wheels; whereby a line of marking fluid can be deposited on a surface as the carriage is wheeled along, the two shields limiting sideways spraying of marking fluid.

Document GB-A-2101181 (Smrt) discloses masking discs (41,42) having essentially cup- shaped inner surfaces which trap marking fluid.

Document GB-A-2111568 (Texalon) discloses separate rigid planar shield discs (3). Document US-A-3,700,144 (Smrt) discloses a masking plate 80 provided with a central opening through which the sprays from cans can pass, and the mask is made of suitable absorbent material to prevent dripping of the marking fluid which does not pass through the opening.

Document EP- A- 1,059,386 (Tricor) discloses a masking disc assembly, suitable for use with a paint line marker (10) which sprays paint onto a surface (25), and includes a disc (24) with a front face (58) which is exposed to paint sprayed from the marking toward the surface. An absorbent pad (62) mounted to the disc front face (58) absorbs paint overspray in use to provide a crisp paint line to the surface. This document also discloses a pair of surface engaging rear wheels 64 rotatably mounted to the frame 12 by a rearwardly extending bracket 66, and opposingly spaced outwardly of the front wheels to avoid marring the freshly painted line.

Document US-A-5,690,740 (Smith) discloses, with respect to Fig. 13, a spray gun in which spray bounce back is suppressed by orientated air curtains 54 from air chisels 12. Shields 70 and 72 are positioned between the spray plume 50 and the air chisels, remote from the surface being sprayed. Document GB-A-2310234 (Rocol Group Limited) discloses disposable line marking apparatus with a holder/actuator having an upper part 14 engageable with the rim of an aerosol canister at the nozzle end, and a lower part 22 engageable to actuate a nozzle valve. The parts 14, 22 are joined together by a resilient linkage 28.

Objects of the Present Invention It is an object of the present invention to provide improved masks for defining the shape of marking fluid when sprayed on a surface.

It is another object of the present invention to provide an improved stabilizer for wheeled line-marking apparatus.

It is a further object of the present invention, to provide an aerosol operating device operative to mitigate against accidental actuation of an aerosol.

It is a yet further object of the invention to provide an improved arrangement for adjusting the line width of a line marking spray apparatus.

Statement of Invention

According to a first aspect of the present invention, a mask for defining the shape of sprayed marking fluid when sprayed on a surface comprises a shape-defining edge and means to provide a gas flow at said shape-defining edge, which gas flow is arranged to direct sprayed marking fluid material from said shape-defining edge and within the shape to be sprayed. None of the above-referred, prior art line-marking apparatus discloses the use of gas flow to define the shape of sprayed marking fluid. Document US-A-5,690,740 (Smith) is applied to a different art / problem, i.e. prevention of spray bounce back, and does not disclose a shape- defining edge or gas flow at the (shape-defining) edge.

In an embodiment of this first aspect, the mask includes a duct to convey gas from a source to said shape-defining edge. The duct may comprise an aperture contiguous with said shape- defining edge and the gas flow may be directed generally across said shape-defining edge.

In a preferred embodiment of this first aspect, the gas source is a battery-powered air impeller. In another embodiment of this first aspect, wheeled line-marking apparatus comprises airflow ducting and a battery-powered air impellors mounted within hub regions of opposed wheels.

According to a second aspect of the present invention, a wheeled line-marking apparatus includes a stabilizer wheel attached to and moveable with respect to the apparatus between laterally extended and closed positions.

In an embodiment of this second aspect, a swing arm, terminating in a castor wheel, is pivoted to the apparatus.

According to a third aspect of the present invention, an aerosol operating device comprises spring means operative between a body of the aerosol and a holder in which the aerosol body is movably mounted, the spring means being biased to complement the action of the aerosol nozzle valve spring; and a nozzle valve opening mechanism acting with mechanical advantage on the aerosol body in opposition to the spring means.

The mechanical advantage may be provided by a bell crank which is pivoted to the holder and has an arm acting on the aerosol body and a remote trigger arm longer than the arm acting on the aerosol body; whereby force applied to the remote trigger arm is mechanically amplified against the bias of the spring means.

An embodiment of this third aspect includes an actuating structure which is removably fixed to the aerosol body, and is acted upon by the spring means and / or the nozzle valve opening means. Preferably the actuating structure comprises a clip in which the aerosol body is removably received, e.g. engaging the aerosol body at an end opposite the valve. The clip may also engage the aerosol body adjacent to the valve.

According to a fourth aspect of the present invention, a marking apparatus movable adjacent to a surface for spraying marking fluid onto that surface comprises a mask which acts to define a boundary of a sprayed area as the apparatus is moved along the surface; the mask being adjustably mounted in the apparatus by a threaded shaft. According to a fifth aspect of the present invention, a marking apparatus movable adjacent to a surface for spraying marking fluid onto that surface comprises a mask with a fixed edge which acts to define a boundary of a sprayed area as the apparatus is moved along the surface; the mask being removably mountable in the apparatus by a projection which is slidably receivable in a co-operating channel.

According to a sixth aspect of the present invention, a marking apparatus movable adjacent to a surface for spraying marking fluid onto that surface comprises a mask with a fixed edge which acts to define a boundary of a sprayed area as the apparatus is moved along the surface; the mask comprising a drip-forming feature which extends over the sprayed area and receives marking fluid accumulated on the mask to form drips which are deposited in the sprayed area in use.

According to a seventh aspect, a line marker aerosol spray nozzle comprises an actuation support (for example a support flange) of larger width than that used in a conventional line marking aerosol spray nozzle. The actuation support is received in a correspondingly enlarged socket or aperture in a compatible line marking apparatus. A conventional aerosol spray nozzle will therefore fall through the enlarged socket or aperture, and so cannot be used effectively in such a line marking apparatus. This nozzle may also be provided with orientation features, such as diametrically opposed lugs set at an acute angle to the major axis of an elongate exit aperture of the nozzle.

Various further preferred features of the invention in its various aspects are defined in the dependent claims.

Brief Description of the Drawings

Illustrative embodiments of the present invention are described below with reference to the drawings, wherein:-

Fig. 1 is a schematic diagram illustrating a spray mask embodying the first aspect of the present invention;

Fig. 2 is a front perspective view of wheeled line-marking apparatus embodying the present invention in its various aspects, with the spray mask at its minimum width, the aerosol at its lowest position, the operating arm lowered and the rear stabilizer wheels in a laterally extended position;

Fig. 3 corresponds to Fig. 2 except that the spray mask is at its maximum width, the aerosol is at its highest position, the operating arm is raised and one rear stabilizer wheel is in a laterally retracted position;

Fig. 4 is a rear perspective view corresponding to Fig. 2;

Fig. 5 is a rear perspective view corresponding to Fig. 3, except that the spray mask is at its minimum width;

Fig. 6 is a detail, enlarged perspective view of the spray mask arrangement for the line- marking apparatus of Figs 1 to 5 and with the spray mask at its maximum width;

Fig. 7 is an exploded sectional side perspective of the wheeled line-marking apparatus of

Figs 1 to 5;

Fig. 8 is a sectional side elevation corresponding to Fig. 7;

Fig. 9 is a sectional front elevation of the spray mask arrangement of Fig. 6 and with the spray mask at its maximum width; Fig. 10 corresponds to Fig. 9, with the exception that the spray mask is its minimum width;

Figs. 11 and 12 are three quarter perspective views of a second wheeled line marking apparatus embodying various aspects of the invention, shown from the front, above and left side, and from the rear, above and left side, respectively; Fig. 13 is a left side view of the apparatus of Figs. 11 and 12;

Figs. 14 and 14a are detailed sectional views of a telescopic operating am of the apparatus of

Figs. 11 - 13;

Fig. 15 is an enlarged perspective view of a removable spray nozzle for use in the apparatus of Figs. 11 - 14a; Fig 16 is a perspective view from in front and above showing the nozzle of Fig. 15 in position in the line marking apparatus, prior to fitment of an aerosol container.

Fig. 17 is a perspective view of the apparatus of Figs. 11 - 13, partially dismantled to show a side member and associated components; and

Fig. 18 is a perspective view of a masking plate used in the apparatus of Figs. 11 - 13, showing impingement and flow of marking fluid. As shown schematically by Fig. I₅ a spray mask 10, for defining the shape of marking fluid when sprayed on a surface, comprises a pair of masking plates 12, 14 mounted to either lateral side of a spray of marking fluid 16 to be sprayed from the nozzle 18 of an aerosol 20; the masking plate pair define the width of the sprayed marking fluid. The bottom edges 22, 24 of the masking plates are located as close as possible to the surface 26 on which a line is to be sprayed. However, a vertical gap A has to be left so as to provide sufficient clearance for surface irregularities. A gap of between 2.5 and 5.0 mm has been found to be sufficient for most purposes. In known line-marking apparatus such a clearance would result in a measure of overspray beyond the lateral separation of the masking plates. Also, sprayed marking fluid would accumulate on the inner masking plate surfaces and collect as drips or droplets along the bottom edges thereof. These drips would normally drop to the sprayed surface, mainly outside the edges of the sprayed line. These two effects, overspray and marking-fluid drips, each tend to blur the edges of lines sprayed by known line-marking apparatus, spoiling line definition.

According to an embodiment of the first aspect of the present invention, air is passed through ducts 28, 30 outside the masking plates 12, 14 to apertures 32, 34 contiguous with the masking plate bottom edges 22, 24. The apertures extend along the length of and just outside the masking plate bottom edges 22, 24 and are angled so as to direct a flow 36 of air inwardly across the masking plate bottom edges 22, 24. This flow of air directs over-sprayed marking fluid and marking fluid droplets back onto the sprayed line; resulting in significantly sharper line definition.

Figs. 2 to 10 illustrate wheeled line-marking apparatus in accordance with a first embodiment of various aspects of the present invention. The apparatus is primarily an assembly of plastics mouldings.

The apparatus generally comprises a body 40 (Figs. 6 - 10) on which a holder 41 for an aerosol canister is slidably retained. An operating arm 42 terminating in a handle 44 having an operating trigger 46 is pivoted to the holder 41. Fig. 2 shows the operating arm at a lower position and Fig. 3 at a higher position. A pushbutton 43 is provided which when depressed will allow free pivoting of the arm 42 to a desired position, and when released will lock the arm 42 substantially in that position. A conventional line-marking aerosol 48 is removeably held in the holder 41. The aerosol 48 is held in the holder 41 by a locking/operating mechanism 56; the operation of which is described below in more detail.

A pair of primary wheels 58, 60 are located vertically below the aerosol 48 and are rotatably attached to the laterally outer side of a pair of side members 62, each located on and laterally slideable with respect to the body 40. Each side member 62 includes a wheel inner blanking plate 68 with a laterally-extending stub axle 70, to which each primary wheel 58, 60 is rotatably journalled. Each blanking plate includes a housing 72 for an impeller or fan 74 powered by an electric motor 76. Air is drawn in axially of the housing 72 through central apertures 73 and is expelled radially and downwardly through a duct 78 formed between the blanking plate 68 and the housing 72. It has been found that, surprisingly, sufficient air flow can be obtained by providing power for the fan motors 76 from a small electric battery, e.g. a type AA 1.2v rechargeable battery, located in a battery housing 79 in the body 40 and controlled by a switch 80 at the rear of the body.

Opposed masking plates 12, 14 are attached to the line-marking apparatus, one mounted to each side member 62, as described in more detail below. Each duct 78 terminates in an elongate aperture 32, 34 contiguous with the masking plate bottom edges 22, 24. The apertures extend along the length of and just outside the masking plate bottom edges 22, 24 and are angled, at approximately 45°, so as to direct a flow of air generally downwardly and inwardly across the masking plate bottom edges 22, 24.

In use, the switch 80 is operated to start the fans 74, the trigger 46 is pulled to open the aerosol and the apparatus sprays a line as it is wheeled along. The air flow, emerging from duct apertures 32, 34 longitudinally along and downwardly across masking plate edges, laterally contains over-sprayed marking fluid and blows droplets of marking fluid that accumulate along the masking plate bottom edges back onto the sprayed line; to produce a well-defined sprayed line.

In an embodiment of the second aspect of the present invention, a pair of swing arms 102, 104, each terminating in a castor wheel 106, are each pivoted to a respective rear corner of one of the side members 62 and can be swung about a vertical axis between a laterally extended 45° position, as shown by Figs 2 and 4, and a laterally retracted or closed position, as shown by Figs 3 and 5 (left swing arm 102). Detent means (not shown) are provided in the side member/swing arm pivots to detain the swing arms releasably at each of the extended and retracted positions, and optionally at one or more intermediate positions. Clearly, the most stable position is with both arms laterally extended, but closing one or the other arm enables a line to be sprayed close to a wall or the like, whilst maintaining a measure of lateral stability. The swing arm 102, 104 at its closed position still leaves the caster wheel located outside the sprayed line. Closing both arms reduces the overall dimensions of the apparatus; both for delivery packing and for storage.

As with other designs of aerosol line-marking apparatus, the spray nozzle 106 is fixed relative to the holder 41 in use and the aerosol can 108 is moved down against the nozzle to open an outlet valve against spring loading. As most clearly shown by Figs 6 to 8, the aerosol nozzle 106 is located in an apertured bracket 110 fixed to the holder 41. In an embodiment of the third aspect of the present invention, an actuating structure comprising a clip 112 is vertically moveable within the holder 41 and locates, at a bottom end 57, over the rim at the outlet end of the aerosol can and snap fits, at its upper end 56, into the dished can bottom. A bell crank 114 is pivoted within the holder 41 with one, longer, arm 116 extending to the pivot axis 118 for the operating arm 42 and the other, shorter, arm 120 pivotally connected at its distal end within a boss 122 on the clip 112; which is biased upwardly by a spring 123 (Fig. 8) operative between the clip 112 and the holder 41. A pull strap 124 made from nylon or other suitable materials extends down within the operating arm 42, with the strap lower end attached to crank arm 116 and the upper end engaging the trigger 46. Pulling the trigger rotates the bell-crank 114 and forces the actuating clip 112, and hence the aerosol can 108, down against the nozzle bracket to open the outlet valve connected to the spray nozzle 106. Accidental opening of the outlet valve is mitigated because the aerosol can 108 is locked to the actuating bar 112 which is biased upwardly by the spring 123 (i.e. against nozzle opening movement). Known line-marking apparatus relies on the nozzle valve spring to resist accidental opening; whereas, in the present invention, the bell crank 114 acts as a mechanical amplifier, providing mechanical advantage that enables the bias of spring 123 to be relatively strong whilst the trigger action can remain relatively light. Clearly, the stronger the spring bias the greater the resistance to accidental aerosol discharge.

In an embodiment of the fourth aspect of the present invention, the lateral separation of the side members 62 is controlled by a transverse shaft 64, having threads of opposite hand at either end. The shaft can be rotated by and is centrally located by a knurled thumb wheel 66 protruding through the rear of the body 40. The distal ends of the shaft each co-operate with an internally threaded sleeve or insert (not shown) in a respective one of the side members 62.

The thumb wheel 66 can be rotated so as to change the masking plate separation, and hence the width of sprayed line, anywhere between 50 and 100 mm. Fig. 2 shows the side members 62 and masking plates at their closest (50 mm) setting and Fig. 3 at their widest (100 mm) setting. The threaded shaft enables the line width to be readily and accurately set to any desired value within this range. It also locks the side members 62 at the selected spacing. Other embodiments are readily possible, adapted to produce wider or narrower lines than the illustrated embodiments.

The holder 41 is vertically moveable relative to the body 40 between three heights, each set by a spring-loaded push button 52 to either side of the body 40, which buttons co-operate with a vertical series of height setting holes 54 in the holder 41. Fig. 2 shows the aerosol at its lowest position and Fig. 3 at its highest. The push button location enables the holder-arm assembly to be removed readily from the body, e.g. for packing in a storage case. In use, the thumb wheel 66 is rotated to set a desired width of sprayed line, an aerosol is inserted into the holder 41 and the push-button 52 pressed to set a desired holder height (the wider the line the higher the aerosol). Different models with different height settings may be used in different markets having different ambient operating temperatures. The aerosol spray pressure, and hence the height of the spray nozzle needed to produce a line of given width, is dependent upon operating temperature.

In an embodiment of the fifth aspect of the present invention, one of the pair of masking plates 12, 14 is removably located on the inner wall of each impeller housing 72; the impeller housing having a pair of longitudinally extending channels 86 into which a T-sectioned projecting rib 88 (Figs. 9 and 10), on the outer wall of the masking plate, can slide. The leading edge of each masking plate 12, 14 has an arcuate, inwardly directed front flange 90 and a forwardly protruding tab 92. The depth of the flanges 90 (i.e. their dimension in the width direction of the line marking apparatus when the masking plates are mounted therein) is such that they meet when the side members 62, and masking plates 12, 14, are at their closest setting. The flanges 90 curve downwardly and rearwardly and further shield the spray area. The tabs 92 assist insertion and removal of the masking plates 12, 14. The lower edge 22, 24 of each masking plate is inwardly chamfered at 94, 96.

Inevitably, some sprayed marking fluid will accumulate on the masking plates in areas where the controlling air flow is not effective. Whilst such accumulation will not directly affect sprayed line definition it will result in some post-use dripping of fluid, after the line has been sprayed and the apparatus moved "off site". The masking plates can be easily removed for cleaning or replacement.

Figures 11 - 16 show a further line-marking apparatus similar to that described above with reference to Figs. 2 - 10, and again embodying the various aspects of the present invention already discussed. This further apparatus differs from that previously described in the following main respects.

Operating arm

As best shown in Figure 14, the operating arm 42 comprises an upper section 42a telescopically slidable within a lower section 42b. The arm 42 can therefore be reduced in length for packing, transport and storage, e.g. in a carrying case (not shown). As shown in Figure 14a, the pull strap connecting the bell crank remote trigger arm 116 to the trigger 46 is formed from two separate parts 124a, 124b. The part 124a has an eye 123 at one end, through which the part 124b is slidably received. Part 124b has a hooked end portion 125 which engages the eye 123 when the operating arm 42 is fully extended, allowing the pull strap to be tensioned and transmit motion of the trigger 46 to the bell crank arm 116. The parts 124a, 124b may be made from plastics but are preferably made from resilient metal, for additional robustness and resistance to stretching. Nozzle

The nozzle 106 is similar to that referred to above, but is shown in more detail in Figures 15 - 17. As shown most clearly in Figure 15, the nozzle has a discharge nipple 150 with a substantially rectangular exit aperture 152. The long axis of this aperture must be oriented transversely of the apparatus in use, to provide a generally fan-shaped, transversely extending spray pattern. For mounting/valve actuation purposes, the nozzle is provided with an actuation support comprising a generally circular flange 154, having a pair of diametrically opposed orientation lugs 156. A nozzle receiving socket 170 is provided on the holder bracket 110. The orientation lugs 156 are received in corresponding diametrically opposed recesses 258 formed in an inner side wall of the socket 170, so that the exit aperture 152 is correctly transversely aligned. The nozzle is fitted to the aerosol valve discharge tube and can be dropped into the socket 170 from above. To assist in properly seating the orientation lugs, the recesses 258 have circumferentially extending lead-in ramps 260. The nipple 150 has a socket 162 at its upper end (Fig, 16) for reception of the aerosol discharge tube. The lugs may be positioned diagonally (at an acute angle to the long axis of the exit aperture) with the recesses correspondingly diagonally disposed in the holder bracket 110 to ensure transverse alignment of the nozzle exit aperture 152. The nozzle flange and the receiving socket may be larger in diameter than the nozzles (valve actuator) used in conventional line marking aerosols. The line marking apparatus is therefore compatible with aerosol canisters equipped with a nozzle having a large flange and/or diagonal orientation lugs as described above, but not with canisters having a standard nozzle/valve actuator. These will fall through the large socket 170 and/or will not be correctly or consistently orientated.

Air intakes

Instead of the apertures 73 positioned towards the centre of the impeller housings 72 and facing inwardly of the apparatus, circular air intake openings 173 are formed in the wheel blanking plates 68, adjacent to the central regions of the impellers. The impellers are not shown in Figures 11 - 18, but their orientation is reversed on the motor shafts compared to that shown in Figure 7. Therefore in the apparatus of Figures 11 - 18 the impeller rotor plate 75 (Fig. 7) is disposed inwardly towards the motor, and the impeller blades 77 are directed outwardly towards the wheel blanking plate 68, surrounding the intake opening 173. To allow air to be drawn into the openings 173 through the wheels 158, 160, these are provided with spokes 159. As air is drawn in from the outer sides of the apparatus through the wheels, there is little danger of sprayed marking fluid being sucked into the impellers and associated ducting.

Masking plates

These are modified to have an inwardly curled rear profile 292 to control diffusion of sprayed marking paint rearwards of the applicator. The two modified masking plates are mirror images of each other, so only one masking plate 214 is described hereafter. The masking plate 214 curves inwardly and rearwardly to form the curled rear profile 292.

In an embodiment of a sixth aspect of the present invention, an inwardly projecting ramp area 134 is provided at the bottom of the masking plate 214 for directing the paint towards the sprayed line before it reaches a chamfered bottom edge 296 of the ramp area. Feet or ridges having drip-forming tips 294 are provided, extending downwardly and inwardly from the lower edge 296. Sprayed marking fluid impinging on the area 215 runs down the surface of the masking plate 214 and towards the chamfered edge 296. From there, the marking fluid runs along the edge 296 and feet towards the drip forming tips 294 and/or is blown there by the air stream emerging from the duct aperture. The tips 294 extend above the marker fluid line 298. Drips detaching from the tips therefore land on the marker fluid line 298. The tips are shaped so that the drips detach before they grow too large. Drips which are too large are liable to form "blots" on the surface being marked. In a simplified form of the marking fluid spraying apparatus, the gas flow ducts and associated gas source may not be required and can be omitted.

Although the invention has been described with respect to wheeled line-marking apparatus, it could readily be applied to spraying any shape, for example a closed-edge shape; the mask having an aperture of the requisite shape and gas ducts to the circumferential edge of the aperture. The invention is readily applicable to hand-held aerosol spray marking apparatus.

Claims

CLAIMS:

1. A mask for defining the shape of marking fluid when sprayed on a surface comprising a shape-defining edge and means to provide a gas flow at said shape-defining edge, which gas-flow is arranged to direct sprayed marking fluid material from said shape-defining edge and within the shape to be sprayed.

2. A mask as claimed in claim 1 and including a duct to convey gas from a source to said shape-defining edge.

3. A mask as claimed in claim 2, wherein the gas source is a battery-powered air impeller.

4. A mask as claimed in claim 3, in which the impeller has an air intake separated from the marking fluid spray path.

5. A mask as claimed in any of claims 2 - 4, wherein the duct comprises an aperture contiguous with said shape-defining edge.

6. A mask as claimed in any of claims 1 to 5, wherein the gas flow is directed generally across said shape-defining edge.

7. Shape-spraying apparatus comprising means to spray marking fluid, a source of gas and a mask as claimed in any of claims 1 to 6.

8. Shape-spraying apparatus as claimed in claim 7 and including a marking fluid aerosol.

9. Shape-spraying apparatus as claimed in claim 7 or claim 8 as dependent upon any of claims 2 to 6, wherein the mask comprises an opposed pair of line-defining edges, each provided with a gas-flow duct.

10. Shape-spraying apparatus as claimed in claim 9 comprising wheeled line-marking apparatus with air-flow ducting and battery-powered air impellers mounted at hub regions of opposed wheels.

11. Wheeled line-marking apparatus, wherein a stabilizer wheel is attached to and moveable with respect to the apparatus between laterally extended and closed positions.

12. Wheeled line-marking apparatus as claimed in claim 11 comprising a swing arm, terminating in a castor wheel, pivoted to the apparatus.

13. An aerosol operating device comprising: spring means operative between an aerosol canister and a holder in which the aerosol canister is movably mounted, the spring means being biased to complement the action of the aerosol outlet valve spring; and an outlet valve opening mechanism acting with mechanical advantage on the aerosol canister in opposition to the spring means.

14. An aerosol operating device as claimed in claim 13, wherein the mechanical advantage is provided by a bell crank pivoted to the holder and having an arm acting on the aerosol canister and a remote trigger arm longer than the arm acting on the aerosol canister; whereby force applied to the remote trigger arm is mechanically amplified against the bias of the spring means.

15. An aerosol operating device as claimed in claim 13 or 14, in which an actuating structure is removably fixed to the aerosol canister, and is acted upon by the spring means and / or the outlet valve opening mechanism.

16. An aerosol operating device as claimed in claim 15 in which the actuating structure comprises a clip in which the aerosol canister is removably received.

17. An aerosol operating device as claimed in claim 16 in which the clip engages the aerosol canister at an end opposite the outlet.

18. An aerosol operating device as claimed in claim 17 in which the clip engages the aerosol canister adjacent to the outlet.

19. Marking apparatus movable adjacent to a surface for spraying marking fluid onto that surface, the apparatus comprising a mask which acts to define a boundary of a sprayed area as the apparatus is moved along the surface; the mask being adjustably mounted in the apparatus by a threaded shaft.

20. Marking apparatus as claimed in claim 19 in which the threaded shaft extends laterally of the direction of movement of the apparatus, whereby the lateral position of the boundary may be adjusted relative to the apparatus.

21. Marking apparatus as claimed in claim 19 or 20 comprising a thumbwheel for rotating the threaded shaft.

22. Marking apparatus as claimed in any of claims 19 — 21, comprising a vertically adjustable mounting for marker fluid spray means.

23. Marking apparatus as claimed in claim 22 in which the spray means mounting comprises a resiliently biased detent arranged to co-operate with a series of height setting holes.

24. Marking apparatus movable adjacent to a surface for spraying marking fluid onto that surface, the apparatus comprising a mask with a fixed edge which acts to define a boundary of a sprayed area as the apparatus is moved along the surface; the mask being removably mountable in the apparatus by a projection which is slidably receivable in a co-operating channel.

25. Marking apparatus as claimed in claim 24 in which the projection is frictionally retained in the channel.

26. Marking apparatus as claimed in claim 24 or 25 in which the channel and/or projection has a T-shaped profile.

27. Marking apparatus as claimed in any of claims 24 — 26 comprising a protruding tab that assists in inserting and removing the mask from the apparatus.

28. Marking apparatus movable adjacent to a surface for spraying marking fluid onto that surface, the apparatus comprising a mask with a fixed edge which acts to define a boundary of a sprayed area as the apparatus is moved along the surface; the mask comprising a drip- forming feature which extends over the sprayed area and receives marking fluid accumulated on the mask to form drips which are deposited in the sprayed area in use.

29. Marking apparatus as claimed in claim 28 in which the drip forming feature comprises a projecting tip.

30. Marking apparatus as claimed in claim 28 or 29 in which the drip forming feature extends from the fixed edge.

31. Marking apparatus as claimed in claim 28 or 29 in which the drip forming feature extends adjacent an aperture or duct through which a gas flows in use so as to direct marker fluid onto the sprayed area.

32. Marking apparatus as claimed in any of claims 24 - 32 in which the fixed edge comprises a lower edge of the mask.

33. Marking apparatus as claimed in any of claims 24 - 32 in which the mask comprises a front flange directed inwardly in front of the sprayed area.

34. Marking apparatus as claimed in claim 33 in which the front flange extends rearwardly and downwardly.

35. Marking apparatus as claimed in any of claims 24 - 34 in which the mask comprises a rear flange directed inwardly over the sprayed area.

36. Marking apparatus as claimed in claim 35 in which the rear flange extends inwardly and rearwardly.

37. Shape-spraying apparatus as claimed in any of claims 7 - 10, or wheeled line-marking apparatus as claimed claim 11 or 12, or an aerosol operating device as claimed in any of claims 13 - 18, or marking apparatus as claimed in any of claims 19 - 36, comprising a removable spray nozzle adapted for reception of a valved outlet of an aerosol container.

38. Shape-spraying apparatus as claimed in any of claims 7 - 10 or 37, or wheeled line- marking apparatus as claimed in claim 11, 12 or 37, or an aerosol operating device as claimed in any of claims 13 — 18 or 37, or marking apparatus as claimed in any of claims 19 - 37, comprising a telescopic arm carrying a spray activation control.

39. A line marker aerosol spray nozzle comprising an actuation support of larger width than that used in a conventional line marking aerosol spray nozzle.

40. A spray nozzle as defined in claim 39 in which the actuation support comprises a flange.

41. A spray nozzle as defined in claim 39 or 40 in which the actuation support has a width of 20 to 35 mm, preferably 21 to 25 mm.

42. A spray nozzle as defined in any of claims 39 - 41 comprising an elongate exit aperture having a major axis transverse to the line axis, preferably normal to the line axis.

43. A spray nozzle as defined in any of claims 39 - 42 comprising orientation formations.

44. A spray nozzle as defined in claim 43 comprising an elongate exit aperture having a major axis transverse to the line axis, said orientation formations comprising a pair of lugs diametrically opposed at an acute angle to the exit aperture major axis.

45. A line-marking apparatus, comprising: a primary wheel; a stabilizer wheel attached to and moveable with respect to the apparatus between laterally extended and closed positions; a mask comprising an edge for defining the shape of marking fluid when sprayed on a surface; a threaded shaft by which the mask is adjustably mounted in the apparatus; ducting and battery-powered air impellers mounted at a hub region of the primary wheel to provide an air flow at said shape-defining edge, which air-flow is arranged to direct sprayed marking fluid material from said shape-defining edge and within the marking fluid sprayed on said surface; a holder in which an aerosol canister is movably mountable, spring means operative between the aerosol canister and the holder, said spring means being biased to complement the action of the aerosol outlet valve spring; and an outlet valve opening mechanism acting with mechanical advantage on the aerosol canister in opposition to the spring means.