Protector cap and wiper for dispenser discharge orifice

Abstract: A finger actuated plunger of a dispenser has a protector cap (27) telescoped over the plunger head (10) for reciprocation independently thereof along the axis of plunger reciprocation. A portion (31) of the cap side wall covers the discharge orifice in the head in a condition of non-use, and the cap side wall has an aperture (32) adjacent such wall portion for alignment with the orifice for uncovering the orifice in a condition of use. A spring (35) extends solely between the head top wall (24) and the cap top wall (29) for resiliently urging the cap into its condition of non-use.

Description: This invention relates generally to a manually operated dispenser having a reciprocable plunger head containing a discharge orifice through which product is dispensed upon head reciprocation. More particularly, the invention relates to a protector cap telescoped over the plunger head, normally covering the discharge orifice during non-use, and automatically uncovering the orifice prior to manual reciprocation of the head. Manually actuated dispensers, such as pump dispensers and aerosols, are known for dispensing a variety of products upon finger actuation of a plunger head or spray button for effecting discharge of product through the spray orifice. The sprayed products may include hair sprays and other resinous containing materials which, upon drying, on exposure to the atmosphere, tend to clog the spray discharge orifice. Clogging interferes with the free flow of discharge by causing sputtering and uneven spray patterns. Protector caps and covers have been devised to prevent the drying out of the discharged material in the discharge spout or orifice and to prevent its contamination. Figure 21 of EP-A-0000688 illustrates a manually operated dispenser comprising a plunger head reciprocable along a central axis thereof, said head having a smooth cylindrical side wall and a top wall, said side wall containing a discharge orifice through which product is expelled upon head reciprocation; a protector cap mounted on said plunger head for reciprocation independent thereof along said axis, said cap having a cylindrical side wall telescoped over said head side wall, and a top wall overlying said head top wall and being spaced therefrom in a condition of non-use, a portion of said cap side wall covering said orifice in said condition of non-use; an aperture in said cap side wall adjacent said wall portion for alignment with said orifice for uncovering said orifice in a condition of use; and a spring for urging said top walls apart for thereby resiliently urging said cap into said condition of non-use, said cap being axially movable relative to said head into said condition of use upon application of finger force to said cap top wall overcoming the spring force of said spring in the direction of head reciprocation for uncovering said orifice, said spring urging said cap into said condition of non-use upon removal of the applied finger force. Whilst this arrangement is satisfactory from a functional point of view it nonetheless has certain disadvantages, notably in terms of manufacturing. In particular, the arrangement requires the presence of a coil spring between the protector cap and the plunger head. The coil spring, being an additional component, as to the cost of the assembly. Further, it is necessary to assemble the coil spring with the protector cap and the plunger during the manufacturing process. Coil springs are relatively difficult to sort and handle in automated processing and accordingly the need to provide the coil spring substantially complicates the manufacturing process. A combined cover and activator for an aerosol can, in which the cover is connected to the activator by integral bow springs, is shown in US-A-4277004. The present invention is characterised in that the spring provided to bias the protector cap into the non-use position is a bow spring formed integrally with the protector cap. Using plastics moulding techniques it is relatively easy to provide a bow spring having the necessary characteristics as an integral part of the protector cap moulding. The provision of the bow spring in this manner does not substantially increase the cost of manufacture of the protector cap and thus, by eliminating the need to provide a separate coil spring reduces the overall cost of the dispenser. Further, and most significantly, the use of a bow spring integral with the protector cap substantially eases automated manufacture of the dispenser by eliminating the need to handle and position a separate coil spring. The invention is additionally characterised in that the bow spring and plunger head interengage to prevent accidental rotation of the protector cap relative to the plunger head. In the preferred embodiment of the invention the plunger head is provided with a depression into which the bow spring extends to prevent accidental relative rotation of the protector cap relative to the plunger head. Accordingly, the need to provide separate means for preventing relative rotation of the protector cap and the plunger head is removed and the overall structure simplified. The invention will be better understood from the following description of a preferred embodiment thereof, giving by way of example only, reference being had to the accompanying drawings wherein: Figure 1 is a vertical sectional view of a known fingertip sprayer having a protector cap and wiper thereon according to the invention, the cap being shown in a position of non-use; Figure 2 is a view similar to Figure 1 with the cap being shown in a condition of use; Figure 3 is a top plan view of the overcap of Figure 1; and Figure 4 is a sectional view taken substantially along the line 4-4 of Figure 1. Turning now to the drawings wherein like reference characters refer to like and corresponding parts throughout the several views, a plunger head 10 for a finger actuated sprayer is shown in Figure 1 which is typically mounted on a dispenser body 11, retention beads 12, 13 respectively on the head and the body cooperating in a known manner to prevent separation of the parts. The body has an upper transverse wall 14 supporting a fixed cylinder 15 in communication with a valved inlet (not shown) from which a dip tube (not shown) extends into the product within the container (not shown) to which body 11 is mounted as in a known manner. A plunger return spring 16 extends between wall 14 and an undersurface 17 of the head, and a hollow piston 18 depends from the head for reciprocation within the pump cylinder. A discharge passage 19 communicates with the hollow piston, and a discharge valve cup 21 is mounted within the head in communication with the discharge passage. The discharge passage terminates in a discharge orifice 22 located in the valve cup. Thus, upon manual reciprocation of the plunger head along its central axis, product is discharged during each compression stroke through the discharge orifice, as known in the art. Although a fingertip pump dispenser is described, the present invention is not limited for use with such a pump dispenser, but is likewise made adaptable for use with an aerosol sprayer as well. Such an aerosol sprayer has a plunger head or an aerosol button 10 as it is sometimes called together with other parts similar to that aforedescribed except for a piston and cylinder. The dip tube extends into the product within the container which includes a gaseous propellent, as well known in the art. The plunger head is of normal shape and construction in that it has a generally cylindrical side wall 23 and a top wall 24 having a depression in which the operator's finger is nested. The top wall likewise has a directional arrow 25 (Fig. 3) formed as a depression in top wall 24, the arrow pointing in the direction of the discharge orifice to orient the operator to the direction of discharge. This depression is shown at 26 in Figure 4. A protector cap 27 of the invention overlies the plunger head in telescoping relationship. The cap has a cylindrical side wall 28 and a top wall 29 forming a bearing surface for the finger of the operator. A side wall portion 31 of the cap covers the discharge orifice in the non-use condition of Figure 1. And, the cap side wall has an aperture 32 adjacent wall portion 31 which is placed into alignment with the discharge orifice in the condition of use of Figure 2 as will be described in more detail hereinafter. In the non-use condition of Figure 1, top wall 29 of the cap is spaced from top wall 24 of the plunger, and spring means extends only between such walls for resiliently urging the cap into its Figure 1 condition of non-use. The lower end of the cap may have an annular, inwardly directed bead 33, interrupted or uninterrupted, engaging lower edge 34 of the plunger head for locking the cap to the head. The spring means acting between top walls 24 and 29 is in the form of a bow spring 35 integral with top wall 29 of the cap and formed during the cap molding opeation. The bow spring, which may be arcuate in shape, is separated from the remainder of the top wall 29 of the cap by transverse slits 36 (Fig. 3), the spring bearing against top wall 24 of the plunger head, or extending slightly into depression 26 thereon, as shown in Figure 4. The bow spring may be of a slightly flatter profile compared to that shown in Figure 1 such that a portion thereof will engage the side walls of depression 26 of the directional arrow, or the directional arrow may be sized so that the bow spring will engage the side walls of depression 26 when in the non-use condition of Figure 1. In such manner, any rotation of the cap relative to the plunger head will be avoided such that aperture 32 will be oriented directly above the discharge orifice to ensure an uncovering of the orifice when the cap is lowered relative to the head. Certainly, other measures may be taken to avoid relative rotation between the cap and the head, without departing from the invention. In operation, application of finger force against top wall 29 of the cap, in the direction of the arrow of Figure 2, axially shifts the cap, independently of plunger head, from its Figure 1 to its Figure 2 position. The cap, when so depressed, axially shifts against the bias of bow spring 35 which typically bends into a complex curve as shown in Figure 2. Aperture 32 is thus brought into alignment with discharge orifice 22 for thereby uncovering the orifice. Continued application of the finger force applied to the cap, in the direction of plunger reciprocation, depresses the plunger head (or spray button) to effect a spray discharge of product through the uncovered discharge orifice and the aligned aperture 32, as shown in Figure 2. The plunger head is depressed against the action of its return spring as in any normal manner. When the desired amount of product has been dispensed upon each pressure stroke of the plunger, the applied finger force is removed, allowing the plunger to return to the upwardly extended position of Figure 1, as assisted by return spring 16, as known in the art. Removal of the applied finger force automatically returns the protector cap to its Figure 1 position from that of Figure 2 as resiliently urged by the unbending of bow spring 35 into its orifice-covering position of Figure 1. The spring force of bow spring 35 must be less than the spring force of return spring 16 to effect lost motion between cap depression and plunger depression to assure an uncovering of the orifice before the plunger is stroked. This relative spring force may be such that bow spring 35 will bend to a lesser extent than shown in Figure 2 before the plunger head is lowered, such that cap top wall 29 need not abut against head top wall 24 before the head is depressed, contrary to that shown in Figure 2. In any event, the bent bow spring will resume its essentially unbent condition of Figure 1 upon release of finger pressure applied to the cap, such that wall portion 31 will again cover the discharge opening when returned to the Figure 1 position for thereby closing the orifice to the atmophere which avoids possible clogging of discharge passage 19 and of discharge orifice 22 during especially prolonged periods of non-use of the dispenser. Such prolonged exposure to air would otherwise adversely affect the qualitive discharge or other physical characteristics. In accordance with another feature of the invention, any accumulation of the dried product at or in the discharge orifice is removed and is further prevented by the provision of a small projection 37 on the inner surface of wall portion 31 of the cap. As shown in Figure 1, this projection is in alignment with the discharge orifice and may slightly project into the orifice in the orifice-covering position. Upon downward axial movement of the cap to the Figure 2 position, the projection simply wipes the orifice and its vicinity clean while removing any dried product as may have accumulated.

Claims: A manually operated dispenser comprising a plunger head (10) reciprocable along a central axis thereof, said head (10) having a smooth cylindrical side wall (23) and a top wall (24), said side wall (23) containing a discharge orifice (22) through which product is expelled upon head reciprocation; a protector cap (27) mounted on said plunger head (10) for reciprocation independent thereof along said axis, said cap (27) having a cylindrical side wall (28) telescoped over said head side wall (23), and a top wall (29) overlying said head top wall (24) and being spaced therefrom in a condition of non-use, a portion (31) of said cap side wall (28) covering said orifice (22) in said condition of non-use; an aperture (32) in said cap side wall (28) adjacent said wall portion (31) for alignment with said orifice (22) for uncovering said orifice (22) in a condition of use; and a spring for urging said top walls (24,29) apart for thereby resiliently urging said cap (27) into said condition of non-use, said cap (27) being axially movable relative to said head (10) into said condition of use upon application of finger force to said cap top wall (29) overcoming the spring force of said spring in the direction of head reciprocation for uncovering said orifice (22), said spring urging said cap (27) into said condition of non-use upon removal of the applied finger force; characterised in that the spring is a bow spring (35) formed integrally with the cap (27), and the bow spring (35) and the plunger head (10) inter-engage to prevent accidental rotation of the protector cap (27) relative to the plunger head (10). The dispenser according to claim 1 characterised in that the plunger head (10) is formed with a depression (26) into which the bow spring (35) extends to prevent accidental rotation of the protector cap (27) relative to the plunger head (10). The dispenser according to claim 1 or claim 2 characterised in that stop means (33,34) acting between said plunger head (10) and said cap (27) are provided for limiting said cap (27) to said condition of non-use under the bias of said bow spring (35). The dispenser according to any preceding claim, characterised in that said cap side wall (28) has an internal projection (37) partially extending into said orifice (22) in said condition of non-use for wiping the orifice (22) clean of any accumulated dried product from the orifice (22) upon the axial movement of said cap (27). The dispenser according to any preceding claim, characterised in that the dispenser has a return spring (16) biasing said plunger head (10) into a return position upon said reciprocation, said return spring (16) having a predetermined spring force, and said bow spring (35) having a spring force less than said predetermined force, whereby the axial movement of said cap (27) is effected before plunger reciprocation.

Inventors: KNICKERBOCKER MICHAEL GENE, KNICKERBOCKER, MICHAEL GENE
Applicants: CALMAR INC, CALMAR INC.
Application year: 1992
Main classification: B65D83
IPC codes: B65D83, B05B15, B05B11