GB2310149A - Spray gun - Google Patents

Abstract

A spray gun comprising a container (2) and a spray head (6) fitted to the container, the spray head (6) being provided with a filling passage (35) through which the container (2) can be filled. The spray gun may comprise a dosing device (16) which is adapted to eject a measured dose of, for example, herbicide into the filling passage (35). The end of the filling passage (35) may comprise a curved rigid tube (8) which extends from the spray head (6) to the base of the container (2) and supports a dip tube (18) of flexible material through which fluid in the container (2) can be drawn into the pumping device (14). The rigid tube (8) may be rotatable relative to the pump housing (6) and the container (2), so that the spray gun may be adapted for spraying at different orientations.

Description

SPRAY GUN This invention relates to a spray gun particularly, although not exclusively, for the application of herbicide.

Conventional hand operated spray guns comprise a container for the material to be sprayed, fitted with a spray head which includes a hand operated pump. The container is in the form of a bottle, and the spray head is mounted on a cap for the bottle. A tube extends from the pump substantially to the base of the container and a flow passage extends from the pump to a spray nozzle. In use, a hand lever on the spray head is operated causing fluid to be drawn up from the container through the tube and ejected from the nozzle.

In order to fill the container, the entire spray head, including the cap, is separated from the container so that the liquid to be sprayed can be introduced to the container. If, for example, herbicide is to be sprayed, herbicide of the necessary concentration must be added directly to the open container or alternatively a dose of the herbicide must be added followed by enough water to dilute the herbicide to the required concentration. This process can be messy and potentially hazardous to the user. Whenever the container needs to be refilled, the container must be separated from the pump housing, thereby withdrawing the tube from the base of the container. If, as is likely, the container is not completely empty when the pump housing is removed, the tube is likely to be filled with herbicide which may come into contact with the user during the re-filling procedure.

Acco1-d1ng-Lo- first aspect of the present invention there is provided a spray gun comprising a container and a spray head fitted to the container, the spray head being provided with spray nozzle and having a spray passage for the flow of the contents of the container to the spray nozzle and a filling passage through which the container can be filled.

Preferably, the end of the filling passage away from the container is flared outwardly to provide a funnel to facilitate filling.

The spray head may comprises a trigger operated pumping device for pumping liquid from the container through the spray passage to the spray nozzle. The pumping device may have a housing which extends across the filling passage, leaving a flow path between the housing and the wall of the filling passage.

Dosing means may be provided on the spray head for dispensing a metered dose of an active ingredient into the filling passage. The dosing means may comprise a dosing device accommodated in a recess formed in the wall of the filling passage.

According to a second aspect of the present invention there is provided a dosing device comprising a plunger which is displaceable within a cylinder, the plunger being slidable on a plunger rod which is mounted for reciprocation within the cylinder over a predetermined stroke, the plunger being provided with a gripping element which prevents movement of the plunger relative to the plunger rod when the plunger rod moves in a first direction and prevents movement of the plunger relative to the cylinder when the plunger rod moves in a direction opposite to the said first direction, so that reciprocal movement of the plunger rod relative to the cylinder causes the plunger to advance along the cylinder in the said first direction in discrete steps.

Preferably, the gripping plunger element comprises a washer which has a body portion secured to the plunger, the body portion having at least one inwardly directed projection which engages the plunger rod and extends out of the plane of the body portion to one side, and at least one outwardly directed projection which engages a wall of the cylinder, the projections extending to the same side as each other out of the plane of the body portion.

In conventional hand operated spray guns, the tube which extends from the pump towards the base of the container is made of flexible plastics material. When purchased, the tube seldom extends right to the base of the container and during the life of the spray gun, the plastics material of the tube tends to age, causing it to shrink and distort, so that gradually the tube tends to move even further from the base of the container.

Also, it is difficult for the user to orient the tube so as to reach the lowest part of the container. Thus, it is usually impossible to draw the last of the fluid from the container.

To avoid this problem, a spray gun in accordance with the present invention may have a second tube of less flexibility than the first tube, which accommodates the first tube to support and orient it.

The second tube may comprise an extension of the filling passage.

According to a third aspect of the present invention there is provided a spray gun comprising a container for liquid to be sprayed, a spray head including a pumping device, a tube of flexible material extending from the pumping device to the base of the container and a second tube of stiffer material than the first tube extending from the housing substantially to the base of the container, the first tube being disposed within and supported by the second tube.

Openings may be provided in a wall of the second tube.

Preferably the second tube is curved and may be connected rotatably to the spray head.

For a better understanding of the present invention, and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figure 1A is a section through a spray gun; Figure 1B is section on the line B-B in Figure lA; Figure 2 is an exploded view of the upper part of the spray gun of Figure 1; Figure 3 is a plan view of a grip washer; Figure 4 is a section on line IV-IV in Figure 3; Figure 5 is a section on line V-V in Figure 3; and 9 Figures Ba to j shows steps in the filling of the spray gun with herbicide and water.

Referring to Figures 1A, 1B and 2, the spray gun comprises a reservoir or container 2 having a threaded neck portion 4 and a spray head 6 screwed to the neck portion 4. The lower end of the spray head 6 is fitted over a rigid support tube 8 which is curved so as to extend substantially to the edge of a base 10 of the container 2. The upper end of the spray head 6 flares outwardly to form a funnel portion 12. Located in the funnel portion 12 is a pump assembly 15 which supports a pump 14 and dosing syringe 16. A flexible dip tube 18 extends from the pump 14 within the support tube 8 substantially to the base 10 of the container 2, and an outlet duct 20 extends from the pump 14 via a flexible tube 21 to a nozzle 22.

A continuous filling passage (represented by arrow 35 in Figure 1B) is provided from the funnel portion 12 to the support tube 8. The support tube 8 has openings 38 distributed along its length. The pump assembly 15 extends across the filling passage 35 but does not entirely obs-uct it, leaving open regions on each side.

The pump 14 comprises a piston 24 displaceable within a cylinder 26 against the action of a spring 28.

The piston 24 is supported by a piston cap 32 which engages a finger operated lever 30 pivotally connected to the funnel portion 12 of the pump housing 6.

A one-way valve 34 is situated in the inlet to the pump 14 at the upper end of the dip tube 18 and allows flow from the dip tube 18 into the pump 14, but prevents flow in the reverse direction. A second oneway valve 36 is situated in the nozzle and allows flow from the pump 14 to the nozzle 22, but prevents flow in the reverse direction.

Referring to Figure 2, the flexible tube 21 comprises a length of plastics pipe 41 into which are moulded strips of copper 43. These strips provide sufficient stiffness to the tube 40 to enable it to hold a particular orientation set by the user of the spray gun.

The one-way valve 36 in the nozzle 22 comprises an inner nozzle 23 housing a valve element 25 which is biased against a valve seat in the inner nozzle 23 by a spring 27 located by a nozzle diffuser 29. An outer nozzle 31 is screwed onto the inner nozzle 23 and retains the nozzle diffuser 29, spring 27 and valve element 25 in position. Rotation of the outer nozzle 31 relative to the inner nozzle 23 moves the nozzle diffuser 29 relative to the inner nozzle 23 and thereby adjust the spray pattern from the spray gun.

The dosing syringe 16 comprises a barrel 42 having an outlet 44 provided with a seal 45 at one end, and a bearing cap 46 at the other end. The barrel 42 may be oval or elliptical cross-section and is supported within a correspondingly shaped recess 48 formed in the pump assembly 15, such that the seal 45 engages a needle 50 secured to the pump assembly 15. .- needle 50 allows fluid to flow from the interior of the barrel 42 into the filling passage 35.

The bearing cap 46 supports a plunger rod 52 for reciprocating movement within the barrel 42. The stroke of the plunger rod is determined by the position of a circlip 54 fitted in a recess on the plunger rod 52 and by a push/pull cap 47 fitted to the end of the plunger rod 52.

The plunger rod 52 supports a plunger 56 and grip washer 58 for sliding movement within the barrel 42.

Referring to Figures 3 to 5, the grip washer 58 comprises an oval plate 60, corresponding to the crosssection of the barrel 42, formed from pressed high tensile steel sheet. Locating apertures 62 are formed in the plate 60 which engage studs 59 moulded on the plunger 56.

The grip washer 56 has a central aperture 64 provided with four inwardly directed tangs which are continuous with the plate 60 and are disposed equidistantly around the periphery of the central aperture 64. In addition, four outer tangs 68 are disposed equidistantly around the periphery of the oval plate 60. As best shown in Figures 4 and 5, the inwardly and outwardly directed tangs 66, 68 are deflected out of the plane of the plate 60 to the same side as each other.

The sequence of operation of the spray gun will now be explained with reference to Figures 6 to 9.

Referring to Figure 6, a dosing syringe 16 filled with herbicide is introduced into the recess 48 in the pump assembly 15, forcing the needle 50 to penetrate the seal 45 in the end of the dosing syringe 16.

As shown in Figure 7, the plunger rod is then pushed into the barrel 42 until the push/pull cap 47 abuts the bearing cap 46. As will be appreciated, the yangs 66 on the grip washer 58 are directed outwardly towards the push/pull cap 47 and as the plunger rod 52 is pushed into the dosing syringe 60, the tangs 66 grip the plunger rod 52. Consequently, the grip washer 58, together with the plunger 56 are driven into the dosing syringe 16 causing a predetermined does of the herbicide to be ejected through the needle 50 into the filling passage 35. The herbicide then falls under gravity through the support tube 8 into the container 2.

The pushing of the plunger 56 into the barrel 42, as described above, supplies a measured dose of herbicide into the container 2. Referring to Figure 8, if a further dose of herbicide is required from the dosing syringe 16, the push/pull cap 47 is pulled outwardly from the barrel 42 until the circlip 54 abuts the bearing cap 46. As the plunger rod 52 is withdrawn the outwardly directed tangs 68 on the grip washer 58 grip the inside surface of the barrel 42 and the inner tangs 66 slide on the plunger rod 52, so that the plunger 56 remains stationary in the dosing syringe 16.

If the push/pull cap 47 is again pushed into the barrel 42, the plunger 56 will be advanced again in the manner described above releasing a further measured dose of herbicide into the container 2.

When the required quantity of herbicide has been added to the container 2, water is poured into the mouth 12 of the spray head 6 and passes into the container 2 through the openings 38 in the support tube 8. As the water is introduced into the pump housing 6, it washes the sides of the filling passage 35, ensuring that all of the herbicide ejected from the dosing syringe 16 passes into the container 2. To improve the mixing of the water and herbicide, water can be poured into the pump housing 6 simultaneously with the ejection of herbicide from the dosing syringe 16. The spray gun may also be shaken to snsure thorollgh mixing.

Herbicide is ejected from the spray gun by drawing the hand operated lever 30 towards the body of the spray head 6. This action forces the piston 24 into the cylinder 26 of the herbicide pump 14, against the action of the spring 28. As the lever 30 is released, the piston 24 is withdrawn from the cylinder under the action of the spring 28, causing the one-way valve 36 in the nozzle 22 to close and causing herbicide to be drawn up the dip tube 18 into the cylinder 26. As the lever 30 is again drawn towards the pump housing 6, the piston 24 forces the herbicide against the one-way valve 34; which closes. The herbicide is then forced up the outlet duct 20 towards the nozzle 22. The herbicide under pressure lifts the valve element 25 from the valve seat in the inner nozzle 23 and allows herbicide to be ejected from the nozzle 22.

Rotation of the outer nozzle 31 relative to the inner nozzle 23 displaces the nozzle diffuser 29 relative to the inner nozzle 23 and hence alters the spray pattern from the nozzle 22. Repeated actuation of the lever 30 provides pulses of spray from the nozzle 22.

When the contents of the container 2 have been used up, the spray head 6 and support tube 8 may be removed from the container 2 and water may be poured into the mouth 12 of the pump housing 6 and into the container 2 to flush the herbicide residues out of the spray gun.

It will be appreciated that the support tube 8 can be rotated relatively to the spray head 6 so as to position the bottom of the dip tube 18 at a desired position within the container 2 to assist in dispensing all of the herbicide mixture in the container.

Although the specific embodiment describes a spray gun for the application of herbicide, the apparatus may be used for spraying any suitable liquid c- ...ix~-es of liquids, such as water and fertilizer.

Furthermore, the dosing syringe could be used independently of the spray gun to provide measured doses of material. For example, the dosing syringe could be filled with a medicinal paste for the oral treatment of animals.

Claims (14)

1. A spray gun comprising a container and a spray head fitted to the container, the spray head being provided with a spray nozzle and having a spray passage for the flow of the contents of the container to the spray nozzle, and a filling passage through which the container can be filled.

2. A spray gun as claimed in claim 1 in which the end of the flow passage away from the container is flared outwardly to facilitate filling.

3. A spray gun as claimed in claim 1 or 2, in which the spray head comprises a trigger-operated pumping device for pumping liquid from the container through the spray passage to the spray nozzle.

4. A spray gun as claimed in claim 3, in which the pumping device has a housing which extends across the filling passage, leaving a flow path between the housing and the wall of the filling passage.

5. A spray gun as claimed in any one of the preceding claims, in which a dosing device is mounted on the spray head, for supplying material into the filling passage.

6. A spray gun as claimed in any one of the preceding claims in which the filling passage has a funnel shaped inlet.

7. A dosing device comprising a plunger which is displaceable within a cylinder, the plunger being slidable on a plunger rod which is mounted for reciprocation within the cylinder over a predetermined stroke, the plunger being provided with a gripping element which prevents movement of the plunger relative to the plunger rod when the p:,;cr -cad moves in a first direction and prevents movement of the plunger relative to the cylinder when the plunger rod moves in a direction opposite to the said first direction, so that reciprocal movement of the plunger rod relative to the cylinder causes the plunger to advance along the cylinder in the said first direction in discrete steps.

8. A dosing device as claimed in claim 7, in which the gripping element has a body portion secured to the plunger, the body portion having at least one inwardly directed projection which engages the plunger rod and at least one outwardly directed projection which engages a wall of the cylinder, the projections extending to the same side as each other out of the plane of the body portion.

9. A spray gun comprising a container for liquid to be sprayed, a spray heading having a pumping device, a first tube of flexible material extending from the pumping device to the base of the container and a second tube of stiffer material than the first tube extending from the housing substantially to the base of the container, the first tube being disposed within and supported by the second tube.

10. A spray gun as claimed in claim 9, in which the second tube forms part of a flow passage which extends through the spray head to the end of the second tube, and through which the container may be filled.

11. A spray gun as claimed in claim 9 or 10, in which the second tube is curved and is rotatable relatively to the spray head.

12. A spray gun as claimed in any one of claims 9 to 11, in which a side wall of the second tube is provided with openings which provide fluid communication between the interior of the second tube and the container.

13. A spray gun substantially as described herein wiç .crerence to and as shown in accompanying drawings.

14. A dosing device, substantially as described herein, with reference to and as shown in the accompanying drawings.