Abstract:
The improvements relate to the connections between the trigger lever (21) and the body (1) of the sprayer device, and to the rod (18) of the pumping piston (17). The rod (18) is coupled to the trigger lever (21), which is snap-inserted, as a fork arrangement, into the body (1) of the sprayer device.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to improvements in manual sprayer devices comprising a body fixable to a container containing the liquid to be sprayed, a cylinder in said body, a piston movable within said cylinder, and a trigger-type operating lever which is rotatably mounted in said body and connected to said piston in such a manner as to move it in the two directions and on which there act elastic return means which react against the body and are out of contact with the liquid to be sprayed. 
     A sprayer device of this type is known for example from U.S. Pat. No. 4,153,203 (TADA). In this known device the structure of the trigger lever is particularly complicated and the piston also has a certain constructional complexity. In this respect, the trigger lever upperly comprises two outwardly projecting lugs for its hinging to the body (this requiring the presence of counteracting means between the two lugs to prevent their accidental escape from the body seats in which they are held), two external projections in a middle position for connecting the return spring, an inner shaped thrust surface and grooves or seats for connecting the piston to enable movement to be transmitted to it in the two directions. The piston itself is formed from two parts, one of which comprises transverse pins for connecting the trigger lever and a tang for deforming a gasket. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     The main object of the present invention is to substantially simplify the structure of the trigger lever by using special original connections between it and the body and piston. 
     A further object of the present invention is to provide improvements by which simpler automation of the assembly of the trigger lever within the body and its bidirectional connection to the piston is achieved. 
     A further object of the present invention is to improve sprayer devices of the known art such as to make them more economical to produce, but without affecting their functionality or their life. 
     These and further objects which will be more apparent from the ensuing description are attained by improvements characterised essentially in that the trigger lever comprises at its upper forked end two heads to be inserted into apertures within the body which are bounded partly by elastically deformable lugs opposing the escape of the heads, and further comprises in an intermediate position a toothed hole for engagement with the piston or its prolongation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The invention will be more apparent from the detailed description of a preferred embodiment thereof given hereinafter by way of non-limiting example with reference to the accompanying drawings, in which: 
     FIG. 1 is a longitudinal middle section through a sprayer device provided with the improvements of the invention; 
     FIG. 2 is a perspective view of the sprayer device; 
     FIG. 3 is a view of the trigger lever taken in the direction of the arrow A of FIG. 1; and 
     FIG. 4 is a detailed sectional view showing the connection between the trigger lever and the body, the section through the lever being taken on the line B--B of FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the figures, the manual sprayer device S shown therein comprises a body 1 to be connected to a container 2 containing the liquid to be dispensed. The connection is made via an axially holed screw cap 3 to be screwed onto the threaded neck of the container, an insert 4 force-fitted into the body 1 and carrying in a tubular appendix 10 a conventional dip tube 5 and traversing said cap 3, and an annular gasket 6which is clamped against the top of the neck of the container 2 by an outerflange 7 of the insert 4 when the cap 3 is screwed onto said neck. 
     A cylinder 8 is provided in the body 1. This cylinder has an aperture 9 which communicates with a channel through which the liquid to be dispensedmoves. This channel is composed of a first portion represented by the dip tube 5 and the tubular appendix 10 which holds it, a second portion formedby a chamber 11 defined by the insert 4 and body 1 and containing with a certain freedom for movement a disc 12 acting as a suction valve, and a third portion indicated by 13 which extends into the body 1 and into a threaded tubular appendix 14 which together with a nozzle screwed to it defines a chamber containing a member 16 acting as a delivery valve and mixing head. The member 16 can be of any known type and will not be further described as it does not concern the present invention. 
     A piston 17 is movably mounted within the cylinder 8 and comprises a hollowprolongation or rod 18 which terminates with a portion of lesser cross-section via a step, or abutment 19A. This terminal portion 19 extends through an intermediate aperture 20 in a trigger lever indicated overall by 21 and rotatably connected to the body 1 in the manner described hereinafter in detail. 
     The intermediate aperture 20 (see also FIG. 3) is provided at the end of anapproximately frusto-conical axially hollow projection 22 on the trigger lever 21. The aperture 20 comprises two sets of saw-teeth 23, the less inclined face of which faces the interior of the projection 22. The two sets of teeth are symmetrical about the axis of symmetry X of the trigger lever 21 and are lacking along two opposing arcs of the aperture 20 symmetrical about the axis X and extending angularly (see angle α) through about 30°-40°. 
     The two sets of teeth enable the terminal portion 19 of the rod to be inserted through the aperture 20 but prevent it from being extracted because any attempt at extraction causes the teeth to bite into the rod material, the chosen material being softer than the lever material. This achieves a reliable unidirectional connection between the lever and piston. 
     The step 19A separating the terminal portion 19 from the greater cross-section portion of the rod 18 of the piston 17 lies within the hollow frusto-conical projection 22. The step at least partly lies againstthe inner face of the projection. 
     The described teeth enable movement to be transmitted in one direction by the trigger lever to the piston (in the case of FIG. 1, towards the left of the rod) because the teeth 23 bite into the material of the rod 18 (theprolongation of the piston 17) to thereby establish engagement between the teeth 23 and the rod 18. Thus, as the trigger lever moves to the left (in the direction of arrow A as shown in FIG. 1), the teeth 23 move with the trigger lever, and as a result of the biting engagement between the teeth 23 and the rod 18, the piston is also moved in the same direction to thereby provide a unidirectional engagement. In addition, movement in the other direction is transmitted by virtue of the contact between the step 19A and the inner face of the frusto-conical projection 22. Thus, as the trigger lever and associated teeth move to the right (as shown in FIG. 1),the teeth disengage from the biting engagement with the rod 18 whereupon the projection or reaction surface 22 engages the step 19A of the piston 17, so that the piston 17 is also moved in the same direction to thereby provide a unidirectional engagement in an opposite direction. 
     The trigger lever also comprises two seats or recesses 30 arranged symmetrically about the axis X in proximity to the top part of the hollow frusto-conical projection 22. The recesses 30 contain the ends of two arched springs 81 (only one of which is visible in FIG. 1) of plastics construction, as is the rest of the device, their other ends resting against supports inside the body 1. 
     The upper end of the trigger lever 21 is fork-shaped (FIG. 3), at the top ends of the relative arms 36 there being provided transverse heads 37 of substantially rectangular contour. A longitudinal rib 38 extends along therear of the arms 36 and terminates at the head, where it comprises a recess 
     At the edges on the top 1A of the body 1 there are provided two parallel grooves 40 extending from a step 1B. Immediately after the step 1B, each groove 40 comprises an aperture 41 into which there projects a part of a tongue 42 forming part of the body 1. The trigger lever 21 is fitted into the body 1 by inserting the heads 37 through said apertures 41 utilizing the flexibility of the tongues 42 or elastically deformable lugs, which then engage in the recess 39 in the ribs 38. The heads 37 are positioned (FIG. 4) on part of the contours of the aperture 41 and indirectly on the tongue 42. In this manner a hinge is formed, about which the trigger lever21 can rotate. 
     It should be noted that because of the particular arrangement of the teeth 23, the shape of the cavity in the projection 22 containing the step 19A of the rod 18, and the particular hinge connection between the trigger lever 21 and the body 1, rectilinear movements can be transmitted to the piston 17 by the trigger lever 21 without the linkage formed in this manner offering any abnormal resistance due for example to jamming betweenthe parts. 
     At that end Z thereof distant from the trigger lever 21, the two arched springs 81, which form the subject of a simultaneous patent application inthe name of the present applicant, are joined together and to the end of anintermediate strip 50 which at its other end carries the threaded appendix 14 (already mentioned) and a front wall 60 for frontwardly closing the body 1. This assembly is fitted into the body 1 by forcing the smaller part of the appendix 14 over the tubular duct 61, which defines the last part of the portion 13 of the liquid path and which forms part of the body1, until the ends Z of the springs 81 reach the supports 35 on the body 1. 
     The piston 17 is then inserted into the cylinder 8 until it reaches its endof travel (to the right in FIG. 1). An adequate portion of the rod 18 remains outside the open end of the cylinder 8. The trigger lever 21 is then inserted into the body 1 as already described. On doing this the freeends of the two springs move into the seats 30 in the trigger lever 21 by sliding along guide surfaces 70 provided on the lever. The trigger lever is then rotated to the right (with reference to FIG. 1) as far as possible. By this means the narrow end 19 of the rod 18 passes through theaperture 20 in the trigger lever 21 and the step 19A of the rod 18 becomes positioned against the inner contour of the projection 22 on the lever. Onreleasing this latter, the springs return the lever 21 and piston 17 into their rest position in which a projecting part 80 of the lever halts against the lower end of the wall 60.