MXPA01002636A - Fluid pump dispenser having product retraction feature - Google Patents

Abstract

A fluid pump dispenser (10) of the loss motion piston type provides for maintaining the discharge ports (33) open a slight interval at the commencement of each plunger upstroke while the pump chamber (21) expands to retract product from the discharge passage (13) into the chamber to thereby avoid the formation of product droplets at the exit end of the discharge spout (12). Such is affected in accordance with one embodiment by reducing the friction force acting between the piston (18) and the pump cylinder (16) relative to the friction force acting between the piston (18) and the stem (11). In another embodiment an inletvalve assembly has a portion lying in the path of the piston which portion is connected by spring legs to a valve portion such that the restoring force of the spring legs shifts the piston together with the stem at the commencement of the plunger upstroke which maintains the discharge passage in open communication with the chamber.

Description

PUMP DISPENSER FOR FLUIDS WITH PRODUCT RETRACTION BACKGROUND OF THE INVENTION This invention relates in general to a pump distributor for fluids that has a shell or pumping cylinder that defines a pumping chamber and has an internal surface and a bottom, a hollow button or discharge spout, which moves between a first extended position and a retracted position, a hollow rod or submersion tube, which moves together with said button and which defines a free end, an annular piston that is externally slidable along the inner surface of the shell and internally it is adjustable to the rod with the possibility of sliding, a spring that tends to keep the button in the first position and a check valve of the inlet to regulate the access and exit of the fluid from the pump chamber, where the piston has an annular projection or annular valve flange oriented towards the bottom and has a plug piece or valve element that: [i] defines a first surface encar the bottom and a second surface opposite the bottom, [ij is applied to the free end of the rod, becoming integral with it, [Ni] on its second surface, comprises an annular cavity in communication with the interior of the rod that forms openings of discharge and [iv] on its second surface, comprises an annular groove that, when To adjust to the ring projection, it is apt to isolate the annular cavity of the pumping chamber. SUMMARY OF THE INVENTION The fluid pump dispenser of the present invention is manually operated, with a hollow piston mounted on a hollow tube that allows a relative sliding during reciprocating movement of the piston inside the pumping cylinder to open and close the discharge through the piston. tube. The fluid pump dispenser of the present invention allows retraction of the fluid in the pump chamber at the start of each return stroke of the plunger to prevent the formation of jets or drops of fluid upon closing the discharge. The function of retraction of the fluid is carried out by means of a modification of the pumping cylinder without the need for additional pieces, thus achieving a significant saving in assembly, operation and capital costs related to the manufacture of the dispenser.

The annular piston, which has a central bore, is mounted on the hollow tube of the plunger to allow reciprocating movement inside the pumping cylinder, which defines, together with the pumping piston, a pumping chamber of variable volume. An inlet duct controlled by an inlet check valve introduces the fluid into the interior of the chamber, while another outlet duct, also controlled by a valve, defined by the hollow tube and terminated in a discharge outlet opening, allows the exit of the pumping chamber. The piston is mounted on the tube in such a way as to allow relative sliding during pumping to open and close the discharge opening leading to the discharge conduit.

During each pressure stroke, when the user lowers the plunger of submersion against the force of a return spring, the tube of the plunger is displaced in front of the piston a certain distance determined by stops acting between the piston and the piston. tube.

At the start of the return stroke of the piston, the submersion plunger tube moves upwards, under the effect of the force of the return spring and in front of the movement of the piston to thereby close the discharge opening when the piston in a valve element located at the lower end of the tube, thus raising the piston during the return stroke together with the plunger and its tube. When moving during its return stroke, the piston increases the volume of the pumping chamber, which reduces the internal pressure below atmospheric and causes the fluid to leave the inlet conduit through a check valve and between in the pump chamber to refill the pump. During the filling operation of the pumping chamber, the discharge valve remains closed while the inlet valve is open.

The drawback is, as indicated above, that drops of fluid frequently form at the outlet of the dispenser. The object of the invention is to prevent this dripping. The pump dispenser for fluids of the present invention has an inlet check valve which includes a spring device acting in the direction of reciprocation and which is located near a bottom wall of the cylinder, within the reciprocating movement path of the piston, the device being compressed of spring by the piston at the end of the pressure strokes and the spring device being able to move the piston from the lower wall at the start of the return strokes to increase the volume of the pumping chamber in the open discharge position, whereby the fluid is retracted from a discharge conduit defined by the hollow tube and from a discharge opening the end of the discharge conduit to prevent the formation of droplets or jets in the opening.

According to the invention, the annular piston, at the beginning of each return stroke of the piston, is moved together with the plunger, thus keeping the discharge opening open in such a way that the discharge duct remains connected to the pumping chamber , inside which there is an increase in volume that causes a loss of pressure. This decrease in pressure while the discharge remains open for a short interval retracts the fluid from the discharge conduit to the expanding pumping chamber, in such a way as to avoid the unwanted formation of unsightly jets, drops or bubbles of the fluid in the outlet end of the discharge conduit.

The inlet valve includes a spring device that acts in the direction of the reciprocating movement and which is located in the path of the piston movement. Thus, at the end of each pressure stroke, the piston is subjected to the force exerted by the spring device when it hits against the base of the piston. This allows the tube and the piston to move together at the start of the return stroke of the plunger, thus maintaining the discharge in the open position for a short interval of the return of the piston that coincides with the actuation of the spring device. While the discharge conduit remains in open communication with the expanding pumping chamber, the negative pressure created by the increase in volume within the chamber displaces the fluid from the discharge conduit to the chamber while, at the same time, it begins to introduce the fluid in the chamber through the inlet duct. The result is an inward withdrawal of the fluid from the outlet end of the discharge path to avoid the formation of jets or drops in it.

Other advantages of the invention will be apparent from the following description of the preferred embodiment, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a vertical sectional image of the fluid pump dispenser of the present invention and represents a closed discharge valve at the end of the upward stroke, Fig. 2 is an image similar to Fig. 1, showing the piston and the tube during the upward displacement once the upward stroke has begun, Fig. 3 is an image similar to Fig. 2, showing a closed discharge valve once the upward stroke has begun, Fig. 4 is an image similar to Fig. 1, showing the tube of the plunger plunger and the piston at the end of the down stroke, In Figs., The same reference numbers have been used to refer to similar and corresponding parts.

DETAILED DESCRIPTION OF THE INVENTION In Fig. 1 there is shown a dispenser for fluids according to the present invention. It includes a submersion plunger equipped with a hollow elongate submersion tube 11 with a discharge spout 12 at its upper end and defining a discharge duct 13. A peripheral skirt 14 allows the plunger to be mounted in an inner sleeve 15 fixed inside. of the upper end of a pump body defining a pump cylinder 16.

The plunger may be blocked both in its resting position, when it is at the upper end of the dispenser, defining a position of upper retention, as when it is pushed into the pumping body, defining a lower holding position.

At the lower end of the submersion tube 11 of the plunger is mounted a hollow annular piston 18 with a central bore 19 which can reciprocate together with the plunger within the pumping cylinder 16, thus defining a pumping chamber of variable volume 21. Simultaneously, the piston 18 is mounted on the submersion tube 11 in such a way as to allow a relative sliding during the manual reciprocating movement. To this end, the end of the inner section of the tube 11 tapers, having a rim 22 which, in the fully elevated position of the plunger, shown in Fig. 1, distances from an opposite inner rim 23 formed in the piston 18. A return spring 24 of the plunger extends between ribs 25 or similar elements on the inner surface of the skirt 14 of the plunger and an inner flange 26 of the liner 15. This return spring 24 is apt to deflect the piston 18 towards its rest position as indicated in Fig. 1.

At the lower end of the tube 11 of the plunger is fixed a valve element 27 with a connector 28 snapped in or otherwise secured within the central bore 19 (Fig. 2) at the narrow end of the tube 11 of the plunger of submersion .. This valve element 27 has discharge openings 33 (Fig.2) adjacent to the lower end end of the tube 11.

The valve element 27 (Fig. 1) has an upwardly open annular groove 31 (Fig. 2) defining a valve seat for receiving an annular valve flange 32 (Fig. 2) together with the piston 18, thus constituting a discharge valve.

In the resting and / or upper retention positions of the plunger, the communication between the pump chamber 21 (Fig. 1) and the discharge duct 13 (Fig. 1) is closed by means of the valve because of the adjustment between the valve flange 32 (Fig. 2) and the valve seat 31 (Fig. 2), so that the discharge openings 33 (Fig. 2) remain closed. Additionally, a vertical annular flange 34 on the piston shows an open annular groove 35 (Fig. 2) for receiving an annular seal 36 (Fig.2) dependent on the inner flange 26 (Fig. 1) of the jacket 15 ( Fig. 1). In this way, any loss of fluid from the pump chamber 21 in the position of FIG. 1 is prevented.

Depending on the lower end of the cylinder, a usual dip tube 39 (Fig. 2) is included that enters the container (not shown) in which the dispenser is mounted and defines an inlet duct 41 (Fig. 2) that is inserted in the pump chamber 21 controlled by an inlet check valve 42 (Fig. 2).

During operation, a downward manual pressure applied against the plunger plunger displaces the tube 11 with respect to the piston 18 initially until the flanges 22 and 23 come into contact, thus displacing the element valve 27 relative to the flange 32 (Fig. 2) to open the discharge openings 33 (Fig. 2). A continuous downward pressure, applied against the plunger, allows the piston 18 to slide inside the cylinder 16 in order to pressurize the fluid during the reciprocating movement of the plunger located in the pump chamber 21 and to discharge the fluid at the end of the spout 12, through the discharge conduit 13. During the subsequent stroke of the plunger, exerted by the force of the retaining spring 24, the volume of the pumping chamber 21 increases and the negative pressure created therein makes that the fluid enters the pumping chamber 21 through an open inlet conduit 41. A retainer element, such as a carrier cage, can be included within the neck of the pump cylinder 16 to limit the movement of the ball valve with respect to its seat, as is common in the prior art.

The "lost movement" produced between the plunger plunger and the piston 18 during the pressure and return strokes usually allows the return of the tube 11 from the end of the down stroke of the plunger piston in front of the piston 18, in order to causing the valve flange 32 (Fig. 2) to re-settle against the groove of the valve 31 (Fig. 2), thereby closing the discharge openings 33 and causing the return of the piston 18 together with the plunger to the position of Fig. 1. During the reciprocating movement of the plunger plunger between the above described pressure and return strokes, small droplets of fluid are often formed at the discharge end of the spout 12 at the end of the downward stroke of the plunger plunger before closing the discharge openings 33. This formation of small drops is problematic, since it involves an undesirable situation for the user.

According to the invention, it is possible for the discharge openings 33 (Fig. 2) to remain open for a short interval at the start of the return stroke of the plunger while the volume of the pump chamber 21 increases, thereby that the open communication between the sub-atmospheric state of the expanding pumping chamber 21 and the discharge conduit 13 causes a small amount of fluid to retract from the discharge conduit 13 to the pumping chamber 21 before being closed. discharge openings 33. Said retraction causes the fluid to be sucked inward from the discharge end of the spout 12, thus preventing the formation of small drops of fluid in the spout 12 at the end of the downward stroke of the plunger, as in the prior art.

In accordance with the invention and as shown in Figs. 1 to 3, the inner diameter D of the pumping cylinder 16 is constant over its entire length and the inlet check valve 42 has a partially spherical portion 48 (Fig. 2) normally seated against a neck section 47 (Fig. 2). ) of the inlet conduit 41 (Fig. 2), as shown in Fig. 2. The inlet check valve 42 also includes a vertical annular wall 49 which is attached in a single piece to the partially spherical portion 48 through of several (two, three or more) spring feet 51. Wall 49 may have external protrusions 52 axially spaced to establish a range of movement of the wall 49 with respect to a protrusion 53 located on the internal wall of the pumping cylinder 16.

During operation, at the end of the downward stroke of the plunger, a piston seal 43 presses against the annular wall 49 of the inlet check valve 42 which is in its path to thereby move the wall 49 slightly towards below, whereby the spring feet 51 are deformed so that a seal is established between the partially spherical portion 48 and its valve seat. Thus, in a situation of lower retention of the plunger, any loss of fluid through the inlet duct during transport and storage is avoided.

At the start of the return stroke of the plunger, shown in FIG. 4, the tube 11 of the plunger starts its return by the force of the return spring 24, in a conventional manner. By including the inlet check valve 42 described above, at the start of the return stroke, the spring force of the spring feet 51 moves the wall 49 upwards, which correspondingly moves the piston 18 upwards together with the movement of the tube 11, thus maintaining the discharge openings 33 open and maintaining for a brief interval an open communication between the discharge conduit 13 and the pump chamber 21, while the valve flange 32 remains out of its seat , which is the slot 31. This open position is maintained while the volume of the pump chamber 21 increases to thereby retract the fluid from the discharge conduit 13 to the chamber pumping 21 in order to eliminate any formation of small drops of fluid at the end of the spout 12, while at the same time releasing the pressure of the spring feet 51 against the partially spherical portion 48, which allows suction to be initiated of the fluid into the pumping chamber 21 through the inlet conduit 41.

Once the spring feet 51 have regained their original shape, as indicated in Fig. 3, the tube 11 of the plunger continues its upward stroke movement with respect to the piston 18, so that the discharge openings 33 close when the valve flange 32 returns to settle in its annular groove 31. As the upward stroke proceeds, the volume of the pump chamber 21 continues to increase, so that it releases the pressure of the spring feet 51 against the partially portion. spherical of the inlet check valve 42, which allows fluid to enter the pump chamber 21 through the inlet conduit 41. Interference between the protuberances 52 and 53 (Fig. 1) limits the movement of the valve Inlet retention 42. This is also advantageous during the assembly of the parts of the dispenser.

From the above it can be seen that a simple and economic approach, although highly efficient, has been adopted to avoid the formation of small droplets of fluid at the end of each pressure stroke, thus avoiding an unsightly and neglected appearance and minimizing contact between the fluid and outside air at the end of the spout, which could lead to blockages.

It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Therefore, it should be understood that, within the scope and spirit of the following appended claims, the invention may be applied differently than specifically described.

Claims (1)

1. CLAIMS Pump dispenser for fluids, comprising: a hollow piston at one end of a hollow tube that performs an reciprocating movement between the pressure and return strokes within a pumping cylinder to thereby define a variable volume pumping chamber, said piston mounted on said tube to allow an alternative reciprocating movement between an open discharge position through said tube and a closed discharge position in which said piston closes against a valve element at said end of said tube, with a conduit input leading to said chamber controlled by an inlet check valve, characterized in that said inlet check valve includes a spring device acting in the direction of reciprocation and which is located proximate a bottom wall of said cylinder, within the travel of said reciprocating movement of said piston, said device being compressed spring by said piston at the end of said pressure strokes and said spring device being able to move said piston from said lower wall at the beginning of said return strokes to increase the volume of said pumping chamber in said open discharge position, with which said fluid is retracted from a discharge conduit defined by said hollow tube and from a discharge opening the end of said discharge conduit to prevent the formation of drops in said opening. The fluid pump dispenser according to claim 1, characterized in that said spring device includes at least one opposite pair of spring feet. The fluid pump dispenser according to claim 1 or 2, characterized in that said inlet check valve includes a partially spherical portion forming a single part of the spring device. The pump dispenser for fluids according to at least one of claims 1 to 3, characterized in that it has a device located between said cylinder able to retain said spring device in said lower wall of said cylinder. The pump dispenser for fluids according to at least one of claims 1 to 4, characterized in that said piston is mounted on a narrow section of said tube.