GB2274495A

GB2274495A - Bayonet fitting for a spray nozzle holder

Info

Publication number: GB2274495A
Application number: GB9401259A
Authority: GB
Inventors: Trevor William Bartlett Swan; Lincoln Scott Soule
Original assignee: Lurmark Ltd
Current assignee: Lurmark Ltd
Priority date: 1993-01-25
Filing date: 1994-01-24
Publication date: 1994-07-27
Also published as: GB9401259D0; GB9301369D0

Abstract

A bayonet fixing for a spray nozzle has at least one lug (2) on a first component (1) and at least one substantially identical lug (6) on a second component (5) to be fixed to the first component (1). Each lug (2, 6) has a ramp portion (3) and a post portion (9) between which is defined a recess (8). On assembly of the two components (1, 5), rotation of one component relatively to the other causes the respective ramp portions (3) to slide over each other, the post portion (9) of each lug then dropping into the recess (8) in the corresponding lug on the other component. <IMAGE>

Description

BAYONET FITTING FOR A SPRAY NOZZLE HOLDER The present invention relates to a bayonet fitting for a spray nozzle holder.

In a spray nozzle used for spraying liquid, particularly in agricultural applications, a nozzle tip is held in a nozzle body by means of a cap. The cap is generally cylindrical and is fixed to the nozzle holder by a bayonet fitting in which a lug on one of the cap and holder is received a recess in the other part, the cap being rotated to lock onto the holder.

A variety of bayonet fittings are known. In one, the nozzle holder has a lug of square cross-section and the cap has a through hole in its circumferential wall, the through hole being profiled to provide a ramp portion over which the lug rides and behind which the lug on the holder rests to lock the cap on the holder.

However, this construction has a number of disadvantages. Firstly, the square lug presents a relatively sharp edge to the ramp on the cap, making it difficult to engage the lug in the recess. Also, whilst the square lug securely prevents rotation of the cap relative to the holder in one direction, in the other direction, there is only the small height of the rear of the ramp over which the lug must ride and it is possible for the cap to work free of the holder in use due to vibration.

According to the present invention, there is provided a bayonet fixing for a spray nozzle, comprising at least one lug on a first component and at least one substantially identical lug on a second component to be fixed to the first component, each lug having a ramp portion and a post portion between which is defined a recess, the arrangement being such that, on assembly of the two components, rotation of one component relatively to the other causes the respective ramp portions to slide over each other, the post portion of each lug then dropping into the recess in the corresponding lug on the other component.

At each lug connection, there are two interfaces in each direction between the respective lugs, particularly where the post portion of one lug engages behind the ramp of the other lug, thereby doubling the work required to release the engagement of the lugs, rendering the components less likely to become detached in use through vibration.

The fixing may include a resilient gasket. The gasket is yields on insertion of one component into the other to allow the lugs to ride over each other.

The lugs may be made of a resilient material which compresses on assembly and disassembly to enable the ramp portions to ride over each another.

An example of the present invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a perspective partially cut-away view of first and second components, each provided with two lugs; and, Fig. 2 is a detail view of the engagement of two corresponding lugs.

In Figure 1, a first component 1 is in the form of a socket and is shown cut away to reveal the interior.

Internally of the socket 1 are a pair of identical lugs 2, the lugs being diametrically opposed. The first component 1 may be a cap which holds a spray nozzle tip (not shown), for example.

The second component 5 is in the form of a pipe, the outer diameter of which is sized so that the second component 5 is a sliding fit in the first component 1. The second component 5 may be the body of a spray nozzle holder, for example. The second component 5 has a pair of diametrically opposed lugs 6 which are substantially identical in shape to the first pair of lugs 2 in the first component 1.

Each lug 2,6 has a ramp portion 3. In a preferred example, the ramp portion subtends an angle of approximately 280 at the centre of the cylindrical component 1,5. The ramp portion 3 passes to a short flat upper surface 4, behind which is a very short and relatively steeper ramp 7. The short ramp 7 leads down to a flat recess 8 which subtends an angle of approximately 350 at the centre of each component 1,5. Behind each recess 8 is a rectangular post section 9 which is upstanding relative to the recess 8. Accordingly, the recess 8 of each lug 2,6 is defined between its rectangular post 9 and the major ramp 3/minor ramp 7 configuration.

To assemble the first and second components 1,5, the second component 5 is inserted into the first component 1 with its respective lugs 6 positioned in the spaces between the respective lug 2 on the first component 1. An axial stop is formed by an end wall 13 of the first component, this end wall 13 having a through-hole 14 through which liquid passes. This end wall 13 limits the maximum extent of insertion of the second component 5 into the first component 1. At this axial stop position, the first component 1 is rotated relatively to the second component 5 causing the respective ramp portions 3 to engage and ride over one another. This riding-over action can be facilitated by the use of a resilient ring-like gasket 12 made of, for example, rubber.As the second component 5 compresses this gasket 12, the ramps 3 are able to ride over each other on rotation of the first and second components 1,5 relatively to each other. The posts 9 then drop into the respective recesses 8 on the other lug and engage each other as shown in Figure 2. The gasket 12 also provides a degree of spring pressure which ensures that the lugs are firmly engaged with each other. Alternatively or additionally, the lugs may themselves be made of a resilient material.

As seen in Figure 2, the "upper" surface of each post 9 is dimensioned to be received in the recess 8 of the corresponding lug on the other component with the inner faces 10 of the lugs abutting each other and the outer faces 11 in engagement with the short ramp portions 7.

Accordingly, to disengage the two components 1,5, it is necessary for each post 9 to ride over a short ramp section 7. Thus, in the example shown, there are four points of engagement in each direction of rotation which act to prevent the component becoming separated and, on each lug pair engagement, there are two short ramp portions over which a post 9 must ride. This represents twice the retaining force provided in some prior art couplings of this type. In other words, twice as much mechanical work must be done to release this "double-lug" coupling.

Claims

1. A bayonet fixing for a spray nozzle, comprising at least one lug on a first component and at least one substantially identical lug on a second component to be fixed to the first component, each lug having a ramp portion and a post portion between which is defined a recess, the arrangement being such that, on assembly of the two components, rotation of one component relatively to the other causes the respective ramp portions to slide over each other, the post portion of each lug then dropping into the recess in the corresponding lug on the other component.

2. A fixing according to claim 1, wherein the fixing includes a resilient gasket.

3. A fixing according to claim 1 or claim 2, wherein the lugs are made of a resilient material.

4. A bayonet fixing for a spray nozzle, substantially as described with reference to the accompanying drawings.