Pump for delivering atomized liquids

Abstract: The invention relates to a pump of very simple low-cost structure comprising a hollow stem (4,5) slidable within a cup-shaped body (1) and acting as a compression piston (4), and a valving element (12,13,14) consisting of an elongate rod movable in the cavity within the stem and provided with a conical collar which is urged by a spring to engage and seal against a conical seat within the stem, so that liquid delivery occurs snapwise when the conical collar disengages said conical seat within the stem (4,5).

Description: This invention relates to a pump for delivering pressurized liquids, the delivery being of the snap-start type to prevent liquid dripping. Many types of pumps applicable to liquid containers are known, operable manually to deliver the liquid in atomized form. For optimum operation, the pump must ensure that the liquid is delivered only under pressure (hence preventing dripping, which would occur if the pressure of the delivered liquid were to fall below a predetermined minimum value) and allow easy pump priming on initial use. These requirements are satisfied only by pumps of complicated structure and hence high cost. Low-cost pumps do exist, but these do not achieve the aforesaid results, or they work unsatisfactorily. For example, the GB-A-2 179 406 discloses a pump having a piston with a hollow stem (30) extending all around a hole (32) formed in a transversal wall (34) of the piston: the passage of the liquid to the cavity of the stem (30) is controlled by a valve body comprising a stopper (36) connected to a crown member (56) by elastic strips (68). Since the crown members may be inserted in the downstream end of the respective stems until the desired position is reached (page 3, lines 1-4, of the British patent) it is practically impossible to position them exactly at the same lenght of the stems, so that the pressure with which the elastic strips (68) press the stoppers (36) against the edge of the hole (32) cannot be the same in all the so obtained pumps which therefore will start to dispense the liquid at different pressures. Further drawbacks of the cited reference stand in that it is very difficult to introduce the short crown member into the relatively long cavity of the stem (30) into which such member (56) and stopper (36) may easily assume an inclined and uncontrolled position with consequent unreliable sealing effect; and in that the cavity of the stem (30) is relatively large (for enabling the crown member (56) to be introduced therein) thus permitting stagnant liquids to stay therein downstream of the valve body (56, 36). The main object of the present invention is therefore to provide a pump of the stated type which is of very simple structure and low production cost, which ensures snap-start of liquid delivery, and which allows easy pump priming on initial use. This and further objects are attained by a pump for delivering pressurized liquids, comprising: an elongate body (1) having at one end a hollow appendix (2) connectable to a dip tube (3); a hollow piston (4) slidable under sealed conditions within said body (1) and having a hollow appendix (5) with a discharge hole at its free end, emerging from the body (1) and acting as stem for mounting a delivery cap (6) thereon; a piston spring (8) for urging said piston (4) out of the body (1) towards and against a stop element (9) rigid with the body and provided with means (10, 11) for fixing the pump onto the mouth of a container containing liquid to be delivered by the pump; a floating member (7) for closing the cavity within the body (1) in proximity to its hollow appendix (2); and a valving element (12, 13, 14) housed within the cavity of said piston (4) and movable therein against the action of a spring (16) to open or close a mouth of the piston facing towards the body (1) as a result of operating the pump, characterized in that said valving element (12, 13, 14) has a first elongate rod portion (14) extending along the cavity within said piston (4) up to the discharge hole of said stem (5), a second oppositely extending elongate rod portion (13) having its free end facing said floating member (7) and a conical body (12) coaxial with said rod portions (13, 14) wherein the cross-section of said conical body (12) is greater than the cross-sections of the rod portions (13, 14); said conical body (12) being close to the second rod portion (13), being acutely conically shaped and with its narrower end facing towards the mouth of the piston (4); the mouth of said piston (4) being defined by a conical surface complementary to the conical surface of conical body (12); said spring (16) acting to urge the conical surface of said conical body (12) towards and against the conical surface of the mouth of the piston (4), the length of said second rod portion (13) being such that its free end within the body (1) rests on and presses against said floating member (7) when said piston (4) is in its position of maximum lowering within said body(1). Preferably the outer free end of said rod portion (14) is housed within and movable in contact with a grooved surface of said discharge hole provided in the free end of said hollow appendix (5). The structure and characteristics of the pump will be more apparent from the description of a preferred embodiment thereof, given hereinafter by way of non-limiting example with reference to the accompanying drawings in which: Figure 1 is a longitudinal section through the pump in its rest state; and Figure 2 is a longitudinal section through the pump in its primed state, ie of maximum lowering of the pump stem. The pump shown in the figures comprises an elongate cup-shaped body 1 from which there extends a hollow appendix 2 on which one end of a dip tube 3 (shown by dashed lines on the drawings) can be mounted, its other end being immersed in the liquid contained in the container (not shown for simplicity) on which the pump has been previously mounted. The cup-shaped body 1 defines a cylindrical cavity housing a hollow piston 4 which is slidable under sealed conditions therein and from which there extends a hollow appendix 5 emerging from the cup-shaped body and acting as a stem on which a delivery cap 6 of known structure is mounted. The cup-shaped body houses in its interior a floating ball 7 (for closing the mouth of the hollow appendix 2) and a spring 8 which urges the piston 4 upwards (with respect to the figures). Escape of the piston 4 from the cavity within the cup-shaped body 1 is prevented by an inner ring cap 9 fixed to the cup-shaped body and secured to an outer ring cap 10, from the lower end of which there extends a cylindrical skirt 11 provided with an internal thread by which the pump can be fitted to the mouth of a bottle containing the liquid to be delivered. The structure of the two ring caps 9, 10, 11 and the manner in which they are connected together is known and can be different from that shown on the drawings. The cavity within the piston 4 houses a valving element consisting of a conical body 12 projecting from an elongate rod, one portion 13 of which extends into the cavity within the cup-shaped body 1 towards the ball 7, and the other portion 14 of which extends along the cavity within the appendix 5 of the piston, to pass through a hole provided in the free end of said appendix 5. The outer surface of the rod portion 14 is in light contact with the hole in the appendix 5, where small longitudinal channels 15 are provided to enable the pressurized liquid to flow into the delivery cap 6 and then into the external environment. The conical body 12 of the valving element is urged by a spring 16 against a conical seat (complementary to the conical surface of the body 12) provided in proximity to the lower end (with respect to the figures) of the cavity within the piston 4. To explain the pump operation it will be assumed that the pump is in the rest state shown in Figure 1, that the pump is mounted on the mouth of a bottle containing a liquid to be delivered (into which the dip tube 3 dips), and that the cavity within the cup-shaped body 1 is filled with liquid, ie that the pump has already been primed. When the delivery cap 6 is pressed with a finger, the liquid present in the cup-shaped body below the piston 4 is immediately put under pressure. A fact of maximum importance is that the conical surface of the body 12 engages under considerable friction the opposing conical surface of the seat provided in the piston 4, so that the valving element 12 becomes suddenly released from the piston only when the liquid pressure exceeds a predetermined value. As a result, the liquid can be delivered by the pump (which in practice undergoes "snap" opening, this being sensed by the finger when operating the pump) only at high pressure, so preventing the liquid being able to drip (and hence without being atomized) from the delivery cap. It can be seen that the portion 14 of the rod fills practically the entire cavity within the appendix 5, so that the liquid quantity remaining trapped in the pump above the valving element is negligible. It can also be seen that the translational movement of the rod portion 14 in contact with the end hole in the appendix 5 keeps the surface clean by preventing the formation of incrustation if the liquid carries solidifiable substances, such as hairspray. The purpose of the rod portion 13 projecting towards the ball 7 is to allow easy pump priming on initial operation. To clarify this, it will be assumed that the pump is still in the state shown in Figure 1, but with only air present within the cup-shaped body. On lowering the piston 4 within the cup-shaped body the air present therein is compressed, however this pressure is insufficient to disengage the conical surface of the body 12 from the opposing conical surface of the piston sealing seat against which the body 12 is urged by the spring 16. Just before the piston 4 reaches the end of its lowering stroke (Figure 2), the free end of the rod portion 13 makes contact with the ball 7, so halting the movement of the rod (and of the valving element), whereas the piston continues its movement for a short distance. The two conical sealing surfaces are hence separated from each other (Figure 2) and the compressed air escapes to the outside of the cup-shaped body, while the ball remains pressed in order to close the aperture in the appendix 2. When the delivery cap is released, the piston 4 firstly rises within the cup-shaped body (under the thrust of the spring 8) until the two said conical surfaces come into mutual contact, after which the piston continues to rise together with the valving element (towards the position of Figure 1), hence causing a vacuum to form within the cup-shaped body. This vacuum causes the liquid to rise into the cup-shaped body (via the appendix 2 and around the ball 7), so that the pump is easily primed, as is clearly apparent.

Claims: A pump for delivering pressurized liquids, comprising: an elongate body (1) having at one end a hollow appendix (2) connectable to a dip tube (3); a hollow piston (4) slidable under sealed conditions within said body (1) and having a hollow appendix (5) with a discharge hole at its free end, emerging from the body (1) and acting as stem for mounting a delivery cap (6) thereon; a piston spring (8) for urging said piston (4) out of the body (1) towards and against a stop element (9) rigid with the body and provided with means (10, 11) for fixing the pump onto the mouth of a container containing liquid to be delivered by the pump; a floating member (7) for closing the cavity within the body (1) in proximity to its hollow appendix (2); and a valving element (12, 13, 14) housed within the cavity of said piston (4) and movable therein against the action of a spring (16) to open or close a mouth of the piston facing towards the body (1) as a result of operating the pump, characterized in that said valving element (12, 13, 14) has a first elongate rod portion (14) extending along the cavity within said piston (4) up to the discharge hole of said stem (5), a second oppositely extending elongate rod portion (13) having its free end facing said floating member (7) and a conical body (12) coaxial with said rod portions (13, 14) wherein the cross-section of said conical body (12) is greater than the cross-sections of the rod portions (13, 14); said conical body (12) being close to the second rod portion (13), being acutely conically shaped and with its narrower end facing towards the mouth of the piston (4); the mouth of said piston (4) being defined by a conical surface complementary to the conical surface of conical body (12); said spring (16) acting to urge the conical surface of said conical body (12) towards and against the conical surface of the mouth of the piston (4), the length of said second rod portion (13) being such that its free end within the body (1) rests on and presses against said floating member (7) when said piston (4) is in its position of maximum lowering within said body(1). A pump according to claim 1, characterised in that the outer free end of said rod portion (14) is housed within and movable in contact with grooved surface of said discharge hole provided in the free end of said hollow appendix (5).

Inventors: MARELLI ANDREA, MARELLI, ANDREA
Applicants: MICROSPRAY DELTA SPA, MICROSPRAY DELTA S.P.A.
Application year: 1995
Main classification: B05B11
IPC codes: B05B11