ES2240356T3 - FLUID PUMP DISPENSER WITH PRODUCT RETRACTION FEATURE. - Google Patents

Abstract

A fluid dispensing pump comprising a piston (18) at one end of a hollow rod (11) that alternately moves by hand between compression and return strokes inside a pump cylinder (16) defining a chamber of variable volume pump (21) for dispensing a liquid product through a discharge channel at the other end of the rod (11), an inlet passage controlled by a valve leading to said chamber (21), the assembly being mounted said piston (18) in the mentioned one end to perform a relative sliding movement during the manual alternation, the said rod (11) defining a discharge passage (13) leading from said chamber (21), means acting between said rod (11) and said piston (18) to limit the relative sliding movement between open and closed discharge positions, a valve element (27) in said mentioned one end of said rod (11) that fits by making seal in said piston (18) in the closed discharge position, first engagement surfaces (43, 44) acting between said end and said piston (18) establishing a first force of friction, and second engagement surfaces (19, 45) acting between said piston (18) and said cylinder (16) establishing a second frictional force, characterized by means that establish a variable interference between said piston (18) and said cylinder (16) in such a way that said first friction force is greater than said second friction force at the start of the return strokes causing the said piston (18) to move with said rod (11) to expand the pump chamber (21) in the open discharge position to retract product from said discharge passage (13) and said nozzle (12) into the mentioned pump chamber (21) to prevent the product from dripping from said nozzle.

Description

Fluid pump dispenser with feature Product retraction.

The invention generally relates to a pump manually operated fluid dispenser that has a hollow piston mounted on a hollow rod to perform a movement of relative slippage during reciprocating piston movement inside the pump cylinder to open and close the discharge through the stem. More particularly the present invention provides the recoil of the product inside the chamber of the pump at the beginning of each piston return stroke to prevent the formation of any spin or drops of product in the discharge opening The product recoil feature is achieved by a modification of the pump cylinder without need for additional parts, thus producing savings significant in the assembly operation and in capital costs linked to the manufacture of the dispenser.

As described in the document US-A-6045008, in the hollow shank of the pump piston is mounted an annular piston that has a central hole to move alternately inside the pump cylinder which together with the pump piston defines a variable volume pump chamber. An entry step controlled by a valve leads into the chamber and a discharge passage controlled by a valve defined by the stem hollow and ending in a discharge outlet opening leads outside the pump chamber. The piston is mounted on the rod to perform a relative sliding movement during pumping to open and close the discharge door that It leads to the discharge step.

The frictional force that acts between the piston and the inner wall of the pump cylinder is typically larger than the frictional force between the wall of the piston bore annular and the opposite outer wall of the piston rod. So  during each compression stroke when the operator presses the piston against the force of a recoil spring, the rod of the piston, because of such a difference in friction forces, is move the piston in advance a given distance determined by the fitting stops that act between the piston and the rod.

At the beginning of the piston return stroke, due to the high frictional force that acts between the piston and the cylinder with respect to the frictional force acting between the piston and rod, the piston rod slides up under the action of the thrust force of the return spring anticipating the movement of the piston to close the door of discharge when the piston touches a valve element in the lower end of the rod, thereby raising the piston during the return stroke together with the plunger and its rod. How consequently, the piston that travels during its return expands the volume of the pump chamber which reduces the internal pressure below atmospheric and induces the product to fall from the inlet passage through a valve non-seated retainer and to the pump chamber to discharge the bomb. During the operation of depressing the pump chamber the discharge valve remains closed while the valve entrance is open.

The document EP-A-0757004 on which it is based the precharacterization clause of claim 1 describes a fluid dispensing pump comprising a piston in a end of a hollow stem that can move alternately manually between compression and return strokes in the inside a pump cylinder defining a pump chamber of variable volume to dispense a liquid product through a discharge channel at the other end of the stem, an entry step  controlled by a valve that leads to said chamber, the mentioned piston mounted on the mentioned end to slide with relative movement during alternative manual movement, defining the aforementioned rod a discharge step that leads to the aforementioned load, means acting between said rod and said piston to limit the relative displacement between open and closed discharge positions, an element of valve in the mentioned one end of the mentioned rod joining in a sealed manner the mentioned piston in the discharge position closed, first lace surfaces acting between the mentioned one end of said piston establishing a first frictional force, and second engagement surfaces that they act between said piston and said cylinder establishing a second frictional force.

An object of the present invention is to improve the manual dispensing pump of the type described above that has a relative displacement annular piston which during the compression and aspiration strokes open and close a door discharge that leads to a discharge opening through the stem. According to the invention, a product recoil feature with a single modification of the diameter of the pump to perform a recoil of the product into the pump chamber to prevent formation of any product droplet in the outlet opening Download The provision of such a feature does not require parts additional but simply the restructuring of a part existing thereby preventing any additional increase in costs of the dispenser. The adaptation of the dispensing pump of according to the invention for the recoil of the product is nothing more than a simple and simple but highly effective procedure and economic.

In accordance with the present invention as here it is claimed, a fluid dispensing pump is presented comprising a piston at one end of a hollow rod manually switching between compression and return strokes in the inside of a pump cylinder that defines a pump chamber of variable volume to dispense a liquid product through a discharge channel located at the other end of the stem, a inlet passage controlled by a valve leading to said chamber, said piston being mounted on the mentioned one end to perform a relative sliding movement during the manual alternative movement, defining the aforementioned stem a discharge step that leads from said camera, means that act between said rod and said piston to limit relative sliding movement between positions open and closed discharge, a valve element in the mentioned one end of the mentioned rod to fit doing seal the mentioned piston in the closed discharge position, first lace surfaces acting between the mentioned a end and the aforementioned piston establishing a first force of friction and second engagement surfaces that act between the mentioned piston and said cylinder establishing a second frictional force, characterized by means that establish a variable interference between the mentioned piston and the mentioned cylinder such that at the beginning of the return stroke the mentioned first friction force is greater than the second force of friction causing the mentioned piston to slide along with the mentioned rod to expand the pump chamber in position Open download to roll back the product from the mentioned discharge step and said nozzle inside the aforementioned pump chamber to prevent product jets from the mentioned nozzle.

Consistent with the preferred configuration of the invention at the beginning of each piston return stroke, the annular piston initially slides out of the bore of pump together with the piston rod thus maintaining the discharge door open in such a way that the discharge step remains in communication with the pump chamber that is now expanding and causing a pressure drop in it. This pressure reduction while the discharge remains open a short interval retracts product from the discharge step to inside the pump chamber that is expanding to do so prevent the invisible and unexpected drip / squirt formation of product at the outlet end of the discharge passage.

In order for the invention to be well understood A configuration according to the invention will now be described.

Fig. 1 a vertical section view of the pump fluid dispenser that incorporates a configuration according to the invention:

Fig. 2 is a view similar to figure 1 showing the piston rod and piston at the end of the stroke falling;

Fig. 3 is a view similar to figure 2 showing the piston and rod after the start of the race upward;

Fig. 4 is a view similar to Figure 2 showing the piston and rod during the trip up after the beginning of the ascending race;

Fig. 5 is a view similar to Figure 2 of another configuration that is not part of the present invention showing the piston and rod at the end of the stroke of compression;

Fig. 6 is a view similar to Figure 5 showing the piston and the rod at the beginning of the race upward;

Fig. 7 is a figure similar to figure 5 showing a discharge valve in closed condition after beginning of the ascending race; Y

Fig. 8 is a view similar to figure 5 showing the piston and rod during the trip up after the beginning of the ascending race.

Returning now to the drawings where similar reference characters refer to corresponding parts and similar of the various views, a fluid dispenser of according to the configuration of the invention is generally designated 10 in Figure 1, similar to that described in US Pat. 6045008 mentioned above, which includes a pump plunger that has a hollow elongated piston rod 11 with a discharge nozzle 12 at its upper end and defining a discharge step 13. A wrap skirt 14 is designed to fit and disengage in the inner slide 15 fixed inside the upper end of a pump body defining a pump cylinder 16 on the which is fitted with an internally threaded closure cap 17 to mount the dispenser in a container (not shown) of the product to be dispensed. In figure 1 the plunger is mounted in a raised interlocking position and is capable of be locked in a low plunger position locked like the one It is described in detail in the aforementioned application. He The present invention is also adapted to be incorporated into the inside of a dispenser without an interlocking property or unlock the plunger, without going beyond the scope of the invention.

A hollow annular piston 18 having a bore center 19 is mounted on a lower end of the piston rod to move alternately together with the plunger inside of a pump cylinder to thereby define a pump chamber 21 variable volume. The piston is similarly mounted on the piston rod for relative movement Sliding during manual switching. For this purpose the lower end section of the stem is constrained presenting a shoulder 22 which in the fully raised position of the piston shown in figure 1 is separated from an inner shoulder 23 faced formed in the piston. A piston return spring 24 extends between suitable or similar ribs 25 in the inner surface of the piston skirt 14 and an inner flange 26 or slide 15, to abruptly push the piston into position remaining from figure 1.

A valve element 27 is fixed at the end inside the piston rod, the element 27 having a pair of 28 protruding legs snapped in or secured by another shape in central hole 29 at the constrained end of the stem of piston to set 33 unobstructed doors, as shown at the lower end of the stem.

The valve element 27 is provided with a annular groove 31 open upwards (figure 2) defining a valve seat to receive an annular valve flange 32 which hangs from the piston.

In the top remaining and / or dead position of the piston, the communication between the pump chamber 21 and the passage of discharge 13 is closed by the valve due to sealed fitting between the valve flange 32 and the valve seat 31 of such so that the discharge doors 33 remain closed. Too a vertical annular flange 34 in the piston has an annular groove 35 open to receive a seal 36 that hangs from the flange inside 26 of the slide 15. This prevents any leakage of product of the pump chamber in the condition of figure 1.

In a lower dead position of the plunger like this as at the end of the low stroke of the plunger, as shown in Figure 2, the ring flange 37 dependent on the element 27 fits making seal inside the vertical flange 38 at the end Bottom of the pump cylinder. And hanging from the lower end there are a typical tube 39 that extends into the interior of the container (not shown) on which the dispenser is mounted and defines an inlet passage 41 inside the pump chamber controlled by an inlet, ball, or check valve 42 Similary. In operation with the plunger unlocked from its position top of figure 1, a pressure applied down manually against the piston initially displaces the rod 11 with in relation to piston 18 until projections 22 and 23 make contact causing the displacement of the valve element 27 away from the valve flange 32 to open the discharge doors 33. Continue  applying the pressure down against the plunger serves to make alternate the piston inside the cylinder to pressurize the product during the alternation of the piston located inside the pump chamber and discharge the same from the end of the nozzle 12 through the download step. During each subsequent race upwards of the piston as the one made by the force of return spring restoration pump chamber expands and a negative pressure created inside causes the product back inside the pump chamber through the passage of entrance open. A ball cage can exist inside of the throat of the pump cylinder to limit the movement of the ball valve from your seat, as in any way normal.

The dead movement between the plunger and the piston during compression and return strokes allow typically the return of the stem from the end of the stroke down the piston in advance of the piston so that cause the valve flange 32 to rest against the groove of valve 31 thereby closing the discharge doors and effecting the piston the return together with the plunger to the position of the Figure 1. During the alternation of the piston between the strokes of compression and return as mentioned above often will product droplets form at the discharge end of the nozzle at the end of the downward movement of the plunger before it Close the discharge doors. This drop formation is problematic because it presents an undesirable condition for the operator.

According to the invention the discharge doors 33 are required to remain open for a short interval of time at the beginning of the plunger return stroke while the pump chamber expands so that open communication between the sub-atmospheric condition of the chamber of the pump that expands and the discharge step causes a small amount of product recedes from the discharge step to inside the pump chamber before the discharge door  closing. Such recoil causes product to be sucked from the inside the discharge end of the nozzle, thus preventing product droplet formation on the nozzle at the end of the stroke down the plunger as before.

During the downward stroke of the plunger the frictional force acting between piston seals 43. 44 and the inner wall of the pump cylinder is greater than the force of friction acting between the wall of the central bore 19 of the piston and the outer wall 45 of the contracted section of the stem of the plunger. This allows the plunger, during the run down the piston, slide relative to the piston as determined by the stops 22, 23 ,. And at the beginning of the upward stroke of the plunger a greater frictional force is exerted between the piston seals and the wall of the pump cylinder compared to that exercised between 19 and 45 what causes the reverse movement, a return of the piston slightly ahead of the return of the piston to close the discharge.

According to a configuration of the invention shown in figures 1 to 4, the inner diameter d of the cylinder of pump in the lower section 46 of it is slightly larger than the inside diameter D standard of the pump cylinder for  The remaining section. The inside diameter d is sized to Do not affect the seal between 43, 44 and the inner wall of the cylinder pump at the end of the downward stroke of the piston as it shown in figure 2, but is nevertheless sized for reduce the frictional force acting between 43, 44 and the wall cylinder inside such that frictional force reduced is less than that between the outer wall 45 and the center bore wall 19 of the piston.

This variable interference established between the piston and the inner wall of the pump cylinder facilitates the piston return movement together with the rod at the beginning of the upward stroke of the piston from the positions of the Figure 2 to those in Figure 3. The greatest frictional force established between 45, 19 that exceeds that established between seals 43, 44 and the inner wall of the pump cylinder in the section 46 allows the piston to return momentarily together with the return of the piston while the discharge doors 33 they remain open to keep the communication between the chamber 21 of the pump and the discharge passage 13. The open discharge condition established during the Pump chamber expansion allows a small amount of product recedes from the discharge step to the inside the pump chamber so as to avoid the formation of droplets at the end of the discharge nozzle while at the same time the expanding volume of the chamber of the pump starts sucking the product from the entrance step through the non-seated inlet ball check valve. When the piston seal 44 reaches the cylinder section of inner diameter D, as shown in figure 4, the largest frictional force between seal 44 and inner wall portion of the cylinder compared to the lowest friction force between the wall 45 in the constrained section of the rod and the wall 19 of the piston bore makes a relative movement of the piston with respect to the piston so as to close the doors of discharge 33 when the pump chamber volume continues expanding and removing product from the entrance step to Compress the camera as in a normal way.

Other configuration that is not part of the The present invention is shown in the figures in which the diameter inside D of the pump cylinder is constant in its length and the inlet check valve is replaced by a inlet valve assembly 47 having a portion portion ball 48 normally seated against a throat section 49 of the input step 41 as shown in figure 5 of a step 41 of valve inlet The inlet valve assembly 47 further includes a vertical annular wall 49 connected integrally with a portion 48 by way of multiple (such as two or three or more) legs of spring 51. Wall 49 may have separate exterior projections axially to establish an order of movement of the wall 49 with respect to the projection 53 provided on the inner wall of the cylinder pump

In operation, at the end of the downward run of the piston the seal 43 of the piston bears against the annular wall 49 of the valve assembly 47 that is on its way to in this way slightly slide down the wall 49 which therefore deforms the spring 51 by making a tight seal between the portion 48 partially spherical and its valve seat. Therefore, in a descending interlocking condition, as described by the Related application described above, avoid any product leak through the inlet passage during Transportation and storage.

At the beginning of the plunger return stroke, As Figure 6 shows, the piston rod begins its return by the recovery force of the return spring 24 as of any normal way. By the provision of valve assembly 47  as described earlier at the beginning of the career of return, the restoring force of the spring leg 51 pushes up to wall 49 which correspondingly push up to the piston along with the movement of the rod, keeping the discharge doors 33 open and holding a communication for a short time open between the discharge passage 13 and the pump chamber when the valve flange 32 remains lifted from slot 31. This open condition exists while the volume of the pump chamber expands to retract product from the download step inside the pump chamber to avoid any formation of drops of product at the end of the nozzle, while at the same time the spring 51 releases the pressure against the portion 48 which It allows the start of the product suction towards the inside of the pump chamber via the entrance passage.

Once the spring leg 51 has recovered its original form, as shown in figure 7, the only force that could act on is due to the friction that acts between piston seals 43, 44 and the inner wall of the pump cylinder. The friction force that is greater than the friction force established between 45 and the wall of the central bore 19 of the piston allows the piston rod, at this stage, to continue its upward stroke relative to the piston with which the discharge is closed by sealing when the valve flange 32 is settle back inside the annular groove 31. As the continuous upward stroke the pump chamber increases even more than volume from that of figure 7 to that of figure 8, such that relieves the pressure of the spring 51 against the valve portion 48 partially spherical allowing the product to be introduced inside the pump chamber via the passage of entry. Cooperation between highlights 52 and 53 limits the valve movement and similarly retains the assembly valve in place during assembly of parts of the dispenser.

From the above it can be seen that it has been presented a simple and economical approach also highly effective to prevent the formation of product droplets in the end of each compression stroke which in turn prevents dirty conditions that prevent slippage and minimize contact between the product and the outside air at the end of the nozzle which could cause obstructions.

Obviously, in the light of the above teachings many other modifications and variations of the present invention are possible. However, it should be understood that within the scope of the appended claims the invention can be implemented in other ways than those specifically
described.

Claims (2)

1. A fluid dispensing pump comprising a piston (18) at one end of a hollow rod (11) that alternately moves by hand between compression and return strokes inside a pump cylinder (16) defining a Pump chamber (21) of variable volume for dispensing a liquid product through a discharge channel through the other end of the rod (11), an inlet passage controlled by a valve leading to said chamber (21), being said piston (18) mounted on the mentioned one end to perform a relative sliding movement during the manual alternation, the said rod (11) defining a discharge passage (13) leading from said chamber (21), means that act between the said rod (11) and said piston (18) to limit the relative sliding movement between the open and closed discharge positions, a valve element (27) at the mentioned one end of the mentioned Adopting rod (11) that fits by making seal on said piston (18) in the closed discharge position, first engagement surfaces (43, 44) acting between said end and said piston (18) establishing a first force of friction, and second engagement surfaces (19, 45) acting between said piston (18) and said cylinder (16) establishing a second friction force, characterized by means that establish a variable interference between said piston (18 ) and said cylinder (16) in such a way that said first friction force is greater than said second friction force at the start of the return strokes causing the said piston (18) to move with said rod (11) ) to expand the pump chamber (21) in the open discharge position to retract product from said discharge passage (13) and said nozzle (12) into the mentioned It gives a pump chamber (21) to prevent the product from dripping from said nozzle. 2. A dispenser according to claim 1, wherein a section of said pump cylinder (16) that defines one of the aforementioned second fitting surfaces (46) it has an inside diameter of a predetermined size larger than the inner diameter of a remaining section (43, 44) of the mentioned cylinder (16) and defines the said setting means.