GB2325290A

GB2325290A - Fluid gun for high pressure jetting

Info

Publication number: GB2325290A
Application number: GB9726391A
Authority: GB
Inventors: Brett Cooper
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-12-13
Filing date: 1997-12-12
Publication date: 1998-11-18
Anticipated expiration: 2017-12-12
Also published as: GB9726391D0; GB9625892D0; GB2325290B

Abstract

A fluid gun comprises a rigid tube 5 supported within at an upstream end and protruding from, a supporting body 2. Near a downstream end of the tube it is supported by a carriage which in the embodiment shown comprises a disc 7 rotatable about its centre. The disc is driven by an air motor 9. The tube is supported off centre in the disc, so that rotation of the latter causes the end of the tube and thus the jet to describe a spiral path as the gun is moved. Although the tube is rigid it has enough flexion for this to be possible. In another embodiment the tube is oscillated linearly so that the jet describes a zig-zag path as the gun is moved.

Description

FLUID GUN The present invention relates to a fluid gun, and in particular to a fluid gun of the type having a tube through which pressurised fluid is lead from the gun, and means for changing the direction of the fluid issuing from the gun.

A number of high pressure fluid guns are available for directing fluid pressurised up to 60,000 psi (4000 bar) and for changing the direction of the fluid issuing therefrom. In a typical fluid gun, a generally rigid tube is fixed to the support or stock at, or very near, the downstream end of the tube, but the tube is supported upstream of this in a movable member which, in use, moves the tube at this upstream region If the upstream region of the tube is moved in a circle perpendicular to the axis of the tube, the fluid issuing from the gun will describe a cone. Such a jet of pressurised fluid is particularly useful in cleaning surfaces (such as concrete) of chemicals and other materials since, as the gun is passed over the surface, the spiralling path of the jet cleans a strip of the surface with minimal parts of the strip being missed. As will be appreciated, the space between consecutive spirals depends on the speed at which the gun is passed over the surface, but the cleaning tends to be very thorough.

The tube is typically a steel tube since this is able to withstand the very high pressures which are required. However, this kind of high pressure gun suffers from some disadvantages. The upstream region ofthe tube is moved by the movable member which is a fixed head which spins. The head requires a high pressure rotating seal, which is not only technically complicated and thus expensive, but is prone to leaking and requires regular maintenance. The motor used to drive the spinning head is typically a hydraulic motor which is heavy and very bulky.

According to the present invention, a fluid gun comprises a support, a generally rigid tube extending from, and supported by , the support, the tube leading pressurised fluid (typically water) from the gun, a carriage member supporting the rigid tube downstream of the region of the tube supported by the support, and movable relative to the support serving, in use, to displace the downstream end of the tube in order to change the direction of pressurised fluid issuing from the tube.

In this specification, a "generally rigid tube" is one which is a "hardwall" pipe which is rigid except for a very small degree of flexibility such as would be found in a steel tube suitable for conveying fluid under high pressures of as much as 60,000 psi (4000 bar).

It is not a tube with a large degree of flexibility. In fact, for a gun of the type falling within the scope of the present invention, a small degree of flexibility is suitable in order to enable the downstream end of the tube to be moved. It has been found that this kind of generally rigid tube is unexpectedly flexible enough to allow this movement. However such a generally rigid tube may be shaped, for example coiled, in such a way that the downstream end of the tube has enough movement for the gun to operate properly.

The present invention permits the rotating seal to be eliminated from the gun since the part of the tube which is moved is downstream of the support. Thus, a gun according to the present invention is simpler and cheaper to manufacture, is more reliable and requires less maintenance.

The carriage member of a preferred embodiment is driven by a motor which is preferably an air motor. This has an advantage over the hydraulic motor used in the prior art in that it is lighter and more compact. For this reason, amongst others, the gun of the present invention weighs less than half that of a prior art gun.

The carriage member can be constructed to displace the tube in more than one way.

According to one construction, the carriage moves the tube in an orbital path so that the fluid issuing from the gun describes a cone. In this construction, the carriage member is an element rotatable about the axis of the cone and having an eccentric hole or bearing in which the downstream region of the tube is held. The bearing is typically an oscillating bearing which allows for the angle change between the tube and the element during rotation.

According to one embodiment, the carriage element is rotatable about a first axis and carries a rotatable member which is rotatable relative to the carriage member, but about a second axis parallel to the displaced from the first axis of rotation. The rotatable member includes a set of external gear teeth and the gun includes a set of internal gear teeth engagable with the external gear teeth, such that as the carriage element is rotated about the first axis, the rotatable member is displaced with the carriage member but is also rotated about the second axis. In this case, it is advantageous if the rotatable member includes a bearing which is disposed eccentrically of the second axis for supporting the downstream region of the tube. Thus, a "spiro" effect is achieved.

According to a second construction, the carriage member displaces the tube linearly so that, as the gun is moved over a surface, the pressurised fluid describes a zig-zag pattern, thus clearing a strip of the surface. The linear displacement is typically generated by the motor, a disc driven by the motor, a connecting rod pivotally attached eccentrically to the disc and a piston attached to the connnecting rod and constrained to be movable linearly.

These constructions are mechanically simple, reliable and easily serviced. Further, in positioning them towards the downstream end of the tube, they are more easily accessible than in the prior art where all moving parts are located close to the rotating seal.

Another preferred feature is the means by which the generally rigid tube is held in the gun.

The tube may be moved longitudinally through the support, and this means that, by adjusting the tube to an appropriate longitudinal position, the focal length of the gun can be changed. This is a very significant advantage, since it gives greater control over the width of strip at a surface being cleaned. The longitudinal position of the tube may be held by a knurled nut which locks the tube in place, or by an arrangement similar to the bolt of a rifle in which a transverse catch carried by the tube can be rotated about the axis of the tube into a locking channel preventing longitudinal movement.

The gun is preferably suitable for use with water up to 60,000 psi (4000 bar), and is supplied with water under pressure from a fluid pressure intensifier.

The air motor is driven by pressurised air from a separate compressor at about 80 psi.

The motor typically drives the downstream region of the tube in its orbital path, or in its linear path, at as much as 2500 rpm.

Two preferred embodiments are described below by way of example only with reference to the drawings in which: Figure 1 is a side view of a first form of fluid gun; Figure 2 is a right end view of the first form of gun; Figure 3 is a sectional side view of the first form of gun; Figure 4 is a sectional end view of the first form of gun; Figure 5 is a sectional view of an end cap of the first form of gun; Figure 6 and 7 are front and side views of the disc of the first form of gun; Figures 8, 9 and 10 are views of the body of the first form of gun without other components; Figure 11 shows the oscillating bearing of the first form of gun; Figure 12 is a side view of a second form of fluid gun; Figure 13 is an end view of the gun shown in Figure 12.

Figure 14 is a sectional side view ofthe second form of gun; Figure 15 is a sectional side view of the second form of gun; Figure 16 is a view of a piston of the second form of gun; Figure 17 is a view of the piston of Figure 16 perpendicular to that figure; Figures 18 and 19 are front and side views of a gudgeon pin of the second form of gun; Figure 20 shows part of the body of the second form of gun; Figure 21 is a side view showing a modified way of locking the tube of either form of gun to its body; Figure 22 shows how alteration of the focal length of either form of the gun affects its operation; Figure 23 is a sectional side view of a fluid gun having a sensor; and Figure 24 is a sectional side view of a further form of fluid gun which supplies a spiralling stream of fluid.

Referring to the drawings, Figures 1 to 4 show a first form of fluid gun 1, which is orbital, the gun having a body 2 with a handle 3 and a trigger 4. A rigid tube 5 passes longitudinally through the body 2 and extends beyond the right-hand end of the gun 1.

The tube 5 in this embodiment is about 620 mm long. The rigid tube 5 is longitudinally movable through the body as is described later in this specification. The rigid tube 5 is a steel tube which is rigid and very strong, able to withstand ultra-high pressures of as much as 60,000 psi (4000 bar).

The left-hand end of the rigid tube 5 ends in a coupling 6 with a flexible hose (not shown) which leads to a fluid pressure intensifier (not shown). The rigid tube 5 fits snugly in the body 2 just above the handle 3. The right-hand end or "downstream region" of the tube 5 exits from the end of the gun, and is supported in a carriage which comprises a disc 7 which is rotatable about its centre, the disc having an eccentric hole shown generally as 8. The axis of the eccentric hole 8 is about 12.5 mm from the axis of rotation. The downstream region of the tube 5 passes through the eccentric hole 8 so that, as the disc 7 rotates, the tube orbits the centre of rotation of the disc.

The disc 7 is driven by an air motor 9 having an axis of rotation generally parallel with the axis of rotation of the disc 7. The air motor 9 also lies at the right-hand end of the gun, and a system of gears 11 enables the motor 9 to drive the disc 7. The air motor 9 is driven by compressed air lead to the gun 1 from a compressor (not shown) at about 80 psi, and through a tube 12. The disc 7 and the gear system Ii are located in an end cap 13.

Figure 5 is a sectional view ofthe end cap 13 in which the gear system 11 is located. The gear system has a lower gear 14 and a disc gear 15. The motor drives the lower gear 14 which is drivingly engaged with the disc gear 15. The disc gear 15 is, in this case, attached to the front face of the disc 7.

Figures 6 and 7 show the disc 7 in which the eccentric hole 8 is clearly shown. An oscillating bearing may be placed in the eccentric hole 8 in order to separate the tube 5 from the disc 7.

Figures 8, 9 and 10 show the body 2 without the tube 5, and without the motor or end cap assembly. The part of the body 2 through which the tube 5 passes is shown clearly in Figure 8 by the reference numeral 16. This gives a snug fit.

In operation, the gun is pointed towards the surface to be cleaned, and the trigger 4 is pulled. High pressure water passes through the tube 5 to form a jet of water, and compressed air passes through the air tube 12 to the air motor 9 of which drives the lower gear 14 about its axis. The disc gear 15 is consequentially driven, and the disc 7 is therefore rotated. The tube 5 is caused to orbit about the axis of rotation of the disc 7 since it passes through the eccentric hole 8. The orbital motion of the tube 5 is permitted by the slightly flexible nature of the otherwise rigid tube 5. It has been found that such a rigid tube does have enough flexibility to carry out this orbital movement.

A second form ofthe invention is shown in Figures 12, 13, 14 and 15, in which movement of the downstream region of the tube is linear. The arrangement of most of the gun is the same as that shown in Figures 1 to 11, and so like parts are given the same numbers and only the differences are described below. In fact, the body shown in Figures 8, 9 and 10 is the same for both forms of the gun 1.

The main modification of the second form is in the end cap, and relates to the way in which the motor 9 drives the tube 5 linearly. The motor 9 drives a motor disc or flywheel 17 which has a connecting rod 18 connected eccentrically of its centre. The connecting rod 18 pushes a piston 19 up and down within a passage which permits only linear movement of the piston 19. The piston 19 includes a through-hole or gudgeon 20 through which the tube 5 passes.

As the motor 9 operates, the motor disc 17 rotates, and the connecting rod 18 converts this rotational movement into linear movement of the piston 19. Thus, the tube 5 is linearly oscillated. It has been found that the rigid tube 5 is flexible enough to make this linear movement, despite being made of steel and being able to withstand the ultra-high pressures required.

Figures 16 and 17 show that the piston 19 has a first through-hole 21 which is cross-bored with a second, smaller through-hole 22. The second hole 22 is slightly opened up as shown in Figure 17.

Figures 18 and 19 show a gudgeon pin 23 which fits into the first through-hole 21 of the piston 19, and is cross-bored with a through hole 24 which aligns with the second hole 22.

Figure 20 shows part 25 of the body 2 which extends to the left of the handle 4 shown in Figures 1,3, 12 and 14. This part 25 is generally tubular, and the coupling between the rigid tube 5 and the flexible tube sits within this part 25. The part 25 includes a slot 26 having three latching positions 27. The coupling (not shown) includes a projecting arm which extends from within the part 25 through the slot 26. The tube 5 is moved longitudinally by sliding the arm along the slot, and locking the arm into position by moving it into one of the latching positions 27. Thus, movement is affected in a similar manner to the bolt of a gun.

An alternative way of moving and locking the tube 5 is to use a knurled lock nut (see Figure 21) which holds the tube 5 against the inside of the body 2.

On moving the tube 5, the focal length of the jet of water issuing from the tube can be changed, thereby permitting the width of strip being cleaned to be adjusted.

Figure 22 shows how, as the tube 5 of either form of gun is moved longitudinally within its body 2, the focal length of the gun changes, thereby controlling the width of the strip of surface being cleaned.

Figure 23 shows a fluid gun which is generally ofthe same type as shown in Figures 1 - 11.

In view of the similarities, this embodiment is not described in detail. However, there are some modifications to this fluid gun which are worth noting. Firstly, the tube 5 emerges from the front of the gun within a shield 41 whereby its tip is protected from damage. A gaiter 42 is disposed within the shield around the tube 5 so as to prevent foreign bodies entering the mechanism of the gun. A sensor 43 is attached to the shield 41, so that in use the sensor 43 senses the distance between the end of the tube 5 and the ground. This enables a user of the fluid gun to maintain the optimum distance from the surface being cleaned.

Referring now to Figure 24, a further form of fluid gun is shown which operates in the same general way as in the above embodiment. For this reason, only the front end of the machine is shown, in which the rigid tube 5 passes longitudinally through the body to extend beyond the right-hand end of the gun. In this embodiment, the carriage includes a large gear 45 which is rotatable about a large gear axis X and to which a main hub 46 is attached to rotate therewith. The main hub 46 rotates within bearings 47 about axis X.

The main hub carries a second spiro hub 47 which is rotatable with respect to the main hub 46, and is supported within further bearings 48. The spiro hub 47 is rotatable about a second axis Y which is parallel to and slightly displaced from axis X. In this case, the separation of the axis is 2.5 mm. Attached to the front end of the spiro hub 47 is a small spur gear 49 which rotates with the spiro hub 47. The spur gear 49 has outwardly pointing (external) teeth which engage with a fixed internally-toothed gear 50 on the inside of the housing.

In addition to this, the spiro hub 47 includes and eccentric hole in which is mounted a selfaligning bearing 51 through which the tube 5 passes. A shield 52 protects the protruding end of the tube, and a gaiter 53 prevents dirt from entering the mechanism.

In operation, an air motor 54 drives a small gear 55 which in turn drives the large gear 45.

Rotation ofthe large gear 45 drives the main hub 46 about the axis X. Since the spiro hub 47 is mounted to rotate about axis Y, and the spur gear 49 is engaged with the internal gears 50, not only is the spiro hub 47 displaced in a circular orbit about axis X, but it also rotates about axis Y.

If the gun is pointed at a surface to be cleaned, the pattern traced by the stream of fluid describes a pattern of flower "petals" as the jet not only describes a relatively large circle, but also a number of smaller circles at the same time. A much simplified pattern is shown in Figure 24. Different petal arrangements may be described depending on the relative number of teeth on each of the spur gear 49 and the internal gear 50. Where the internal gear includes 100 teeth, and the spur gear includes 90 teeth, revolution of the spiro hub 47 must take place twenty times before the same pattern is repeated. Clearly, since this tool is intended for cleaning purposes, it may be advantages to have a large number of revolutions before the same pattern is repeated so as to fill in the gaps between the lines making up the petals. According to one embodiment, the internal gear includes 101 teeth, and the spare gear includes 90 teeth. The spiro hub 47 must then rotate 101 times before the same pattern is repeated. This gives very fine cleaning. Clearly, the number of teeth in each of the gears depends on the requirements of the tool for the particular job.

In the embodiments described above, the generally rigid tube is a hardwall pipe, typically being made of stainless steel and having an outer diameter of 1/4 inch (6.35mm) and an inner diameter of about 80 thousandths of an inch (about 2mm).

Claims

CLAIMS:

1. A fluid gun comprising: a support, a generally rigid tube extending from and supported by the support, the tube serving to lead pressurised fluid from the gun; a carriage member supporting the rigid tube downstream of the region of the tube supported by the support and moveable relative to the support, serving, in use, to displace the downstream end of the tube in order to change the direction of pressurised fluid issuing from the tube.

2. A fluid gun according to claim 1, wherein the carriage member includes a carriage element which is moveable to displace the downstream end of the tube in an orbital motion.

3. A fluid gun according to claim 2, wherein the carriage element is rotatable about a first axis substantially parallel with the longitudinal axis of the gun.

4. A fluid gun according to claim 3, wherein the carriage element includes an eccentric region which holds the downstream region of the tube.

5. A fluid gun according to claim 4, wherein the eccentric region includes a bearing which supports the downstream region of the tube.

6. A fluid gun according to any one of claims 2 to 5, wherein the carriage element is a disc.

7. A fluid gun according to any one of claims 2 to 4, wherein the carriage element is rotatable about a first axis and carries a rotatable member which is rotatable relative to the carriage member but about a second axis parallel to but displaced from the first axis of rotation, the rotatable member including an external surface, the gun including an internal surface engagable with the external surface, such that, as the carriage element is rotated about the first axis, the rotatable member is displaced with the carriage element, but is also rotated about the second axis.

8. A fluid gun according to claim 7, wherein the external and internal surfaces are sets of gear teeth.

9. A fluid gun according to claim 8, wherein the rotatable member includes a bearing eccentric of the second axis for supporting the downstream region of the tube

10. A fluid gun according to claim 1, wherein the carriage member includes a carriage element which is moveable to linearly displace the downstream end of the tube.

11. A fluid gun according to claim 10, wherein the carriage element is moveable up and down, when considering the gun held in a ready-to-use position pointed towards the ground.

12. A fluid gun according to claim 10, wherein the carriage element is moveable from side to side, when considering the gun held in a ready-to-use position pointed towards the ground.

13. A fluid gun according to any one of claims 10, 11 and 12, wherein the carriage includes a rotatable element and a connecting rod eccentrically connected to the rotatable element, and wherein the carriage element is a piston connected to the connecting rod.

14. A fluid gun according to any one of the preceding claims, further including a motor for driving the carriage member.

15. A fluid gun according to claim 14, wherein the motor is a hydraulic motor.

16. A fluid gun according to any one of the preceding claims, further comprising means for adjusting the focal length of the pressurised fluid issuing from the tube.

17. A fluid gun according to claim 16, wherein the said focal length adjusting means is a means for selectively holding the tube in at least two positions longitudinally displaced from each other along the support.

18. A fluid gun according to claim 17, wherein the said tube holding means includes a knurled nut which is operable to lock the tube in a selected position.

19. A fluid gun according to claim 17, wherein the said tube holding means includes a transverse catch rotatable about the longitudinal axis of the tube, and the support includes locking channel into which the transverse catch is engageable to select a longitudinal position.

20. A fluid gun according to any one of the preceding claims, further comprising a source of pressurised fluid.

21. A fluid gun according to claim 20, wherein the source supplies fluid pressurised at up to 60,000 psi.

22. A fluid gun according to any one of claims 14 to 21, further comprising a source of pressurised air for driving the motor.

23. A fluid gun according to any one of the preceding claims further comprising a shield disposed around the downstream end of the tube.

24. A fluid gun according to any one of the preceding claims further comprising a flexible gaiter around part of the downstream end of the tube.

25. A fluid gun according to any one of the preceding claims further comprising a sensor for sensing the distance of the gun from a surface being cleaned.

26. A fluid gun constructed and arranged substantially as herein described with reference to Figures 1 to 11, or to Figures 12 to 19, to Figures 20 to 22, to Figure 23, or to Figure 24.