GB2297930A

GB2297930A - Jet/spray nozzles

Info

Publication number: GB2297930A
Application number: GB9503239A
Authority: GB
Inventors: John Joseph Haisley
Original assignee: Sword
Current assignee: Sword
Priority date: 1995-02-20
Filing date: 1995-02-20
Publication date: 1996-08-21
Anticipated expiration: 2015-02-20
Also published as: GB9503239D0; GB2297930B

Abstract

A jet/spray nozzle is adjustable between a jet mode and a spray mode according to the axial position of a control collar 16 mounted on the nozzle tube. A piston 21 slidable in the tube is driven forwards by fluid flowing under pressure to force a ball 29 into engagement with the collar. This permits the collar 16 to be maintained in a selected position on the tube against the bias of a spring 20 tending to return the collar to the spray mode position. However, when fluid ceases to flow in the tube the piston returns under the influence of a spring 23 to permit the ball to drop into a groove 26. This disengages the collar from the tube so that the collar is moved to the spray mode position by the spring 20.

Description

JET/SPRAY NOZZLES This invention relates to jet/spray nozzles, used for example in firefighting.

Jet/spray nozzles are nozzles in which the angle of liquid discharge can be adjusted through a range of cone angles between a jet mode in which liquid is discharged under pressure in a straight jet substantially along the longitudinal axis of the nozzle and a spray mode in which liquid is discharged as a wide angle conical spray.

In the jet mode, with water pressure used in firefighting typically exceeding 5 bars at flows upwards of 400 litres/minute, the reaction force on the operator can be considerable. This is a particular problem where the nozzle opens in the jet mode, because the full reaction force or hydraulic shock is immediately taken by the operator. This can be dangerous.

It is an object of the invention to provide a jet/spray nozzle in which this problem is mitigated.

Accordingly, the invention provides a jet/spray nozzle adjustable between a jet mode and a spray mode according to the position of a control member mounted on the nozzle, wherein the control member is maintained in a selected position on the nozzle by the pressure of fluid flowing through the nozzle and automatically returns to the position corresponding to the spray mode when fluid ceases to flow.

The advantage of the invention is that when the nozzle is turned on it is guaranteed to be in the spray position where reaction forces largely cancel each other as they are mainly directed radially inwards towards the axis of the nozzle. Thus the operator can adjust the nozzle from the spray mode to the jet mode at his own rate so as to gradually assume the full force of the reaction to the water jet.

An embodiment of the invention will now be described, in which: Figure 1 is a longitudinal cross-section of an embodiment of jet/spray nozzle according to the present invention when there is no fluid flow, Figure 2 is a cross-section of the nozzle of Figure 3 when there is flow at pressure and the nozzle is in the spray mode, and Figure 3 is a cross-section of the nozzle of Figure 3 when there is flow at pressure and the nozzle is in the jet mode.

The nozzle comprises a tube 10 through which a fluid such as water under pressure flows in the direction indicated by the arrow 11 when the nozzle is open and in use. This direction will be referred to herein as the forward direction. A diffuser 12 which is basically a cylinder with an outwardly flared end 13 is mounted co-axially within the tube 10 so that the fluid flows in the annular gap 14 between the diffuser and the tube. The flared end 13 of the diffuser is located slightly beyond the forward end of the tube 10.

The diffuser 12 is held in position by radial supports 15 which are designed to offer as little impedence to the flow of fluid as possible consistent with the need to hold the diffuser 12 fixed in position against the force of the fluid flow.

A control collar 16 is slidably and rotatably mounted on the tube 10 for movement axially of the tube 10 between the position shown in Figures 1 and 2 and the position shown in Figure 3. In the former position the forward end of the collar 16 is approximately level with the forward end of the tube 10, so that when fluid 17 flows through the nozzle it escapes largely radially from the nozzle in a wide angle cone 17' (Figure 2).

However, when the collar 16 is in the position shown in Figure 3 its forward and extends over and beyond the flared end 13 of the diffuser so that the fluid 17 is constrained to leave the nozzle in a straight jet 17" substantially along the longitudinal axis of the tube 10. Therefore, when the collar 16 is in the position shown in Figure 2 the nozzle is in the spray mode and when the collar 16 is in the position shown in Figure 3 the nozzle is in the jet mode.

The collar 16 has an annular lip 18 on its inside surface which enters a groove 19 in the exterior surface of the tube 10. A helical spring 20 surrounding the tube 10 is located under compression within the groove 19. The spring 20 acts against the lip 18 to bias the collar 16 rearwardly into the spray mode position shown in Figures 1 and 2. Although the collar 16 can be pushed forwardly on the tube 10 in the absence of fluid flow through the tube 10, there is nothing to hold it there and when it is released the spring 20 will automatically return the collar to the spray jet position. In order to permit the collar to be moved forwardly to the jet position and remain there, it is necessary for fluid to be flowing under pressure in the tube 10 as will now be described.

A hollow piston 21 is slidably mounted in the tube 10 on a rearward extension 22 of the diffuser 12.

A spring 23 under compression on the extension 22 biasses the piston 21 against a stop 24 at the rear end of the extension 22 and this is the normal position of the piston when there is no fluid flowing through the tube 10. The rear wall of the piston consists of radial supports 25 which, like the supports 15, are designed to provide as little impedence to the flow of fluid as possible.

The outside surface of the piston 21 has a circumferential groove 26 machined therein and the rear wall of the groove 26 is inclined radially outwards relative to the tube axis to provide a conical surface 27. The wall of the tube 10 has a hole 28 which loosely retains a ball 29, the ball resting in the groove 26. The interior surface of the collar 16 has a helical channel 30.

When there is no fluid flowing through the tube 10 (Figure 1) the piston 21 is biassed rearwardly against the stop 24 and the ball 29 rests on the bottom of the groove 26. In this position the ball 29 lies just below the outside surface of the tube 10 and does not provide any impediment to the movement of the collar 16 on the tube 10. However, when the nozzle is opened and fluid 17 is flowing under pressure through the tube 10 the pressure of the fluid acting primarily on the rear annular surface 31 of the piston 21 forces the latter forwardly in the tube against the bias of the spring 23 until the front end of the piston 21 comes up against an internal step 32 in the tube 10.

This movement of the piston 21 forces the ball 29 to travel up the conical surface 27 so that the ball comes to rest on the outside surface of the piston behind the groove 26 and engages in the helical channel 30, as shown in Figure 2.

This establishes a screw-threaded engagement of the collar 16 on the tube 10 which is maintained all the time the fluid pressure is acting on the piston 21.

Now, by rotating the collar 16 it can be moved axially forward to obtain various angles of discharge of the fluid, from the wide-angle spray pattern shown in Figure 2 to the straight jet shown in Figure 3.

Provided the fluid pressure is maintained the ball 29 will remain engaged in the helical channel 30 so that the collar 16 will remain at any selected axial position on the tube 10.

However, as soon as the nozzle is turned off and fluid flow ceases, the removal of the fluid pressure on the rear surface 31 of the piston 21 will cause the spring 23 to push the piston back against the stop 24.

This will permit the ball 29 to disengage from the helical channel 30 and fall back into the bottom of the groove 26. There now being nothing opposing the bias of the spring 20, the collar 16 will return to the spray mode position shown in Figure 1.

Claims

1. A jet/spray nozzle adjustable between a jet mode and a spray mode according to the position of a control member mounted on the nozzle, wherein the control member is maintained in a selected position on the nozzle by the pressure of fluid flowing through the nozzle and automatically returns to the position corresponding to the spray mode when fluid ceases to flow.

2. A nozzle as claimed in Claim 1, wherein the nozzle comprises a tube for the passage of fluid and the control member comprises a collar mounted on the tube for displacement in the axial direction of the tube between jet mode and spray mode positions, the nozzle further including means for biassing the collar towards the spray mode position and means responsive to the pressure of fluid flowing through the tube to provide a mechanical purchase of the collar on the tube in opposition to the biassing means to enable the collar to remain at a selected axial position on the tube.

3. A nozzle as claimed in Claim 2, wherein a piston is slidably mounted in the tube and further biassing means are provided which bias the piston in the direction opposite to that of fluid flow such that when fluid flows under pressure through the tube the piston is displaced in the same direction as the fluid in opposition to the further biassing means, and wherein said displacement of the piston operates to establish the said mechanical purchase of the collar on the tube.

4. A nozzle as claimed in Claim 3, wherein a hole in the wall of the tube accommodates an element which is displaced radially outwards by the piston into engagement with the collar when the piston is displaced by the fluid, the element providing the mechanical purchase of the collar on the tube.

5. A nozzle as claimed in Claim 4, wherein the interior surface of the collar has a helical channel which is engaged by the element when the latter is displaced radially outwards by the piston, the engagement of the element with the channel providing a screw threaded engagement of the collar on the tube when fluid flows under pressure through the tube.

6. A nozzle as claimed in Claim 5, wherein the element is a ball and the surface of the piston engaged by the ball is inclined relative to the axis of the tube so that when the piston is displaced by the fluid the inclined surface forces the ball radially outwards by a camming action.

7. A jet/spray nozzle substantially as described with reference to the accompanying drawings.