Pump with cup-shaped diaphragm for trigger dispensers

Abstract: A pump for liquids comprising a hollow cylindrical support body (1) having an annular channel (20) formed at a first end (1b) of the body and open towards the internal cavity (12) of the body, a delivery duct projecting radially from the hollow cylindrical body (1) and being in communication with the annular channel (20) by means of an orifice (21), a pumping member (14) in the form of a resiliently-flexible, cup-shaped diaphragm which has its cavity facing the channel (20), and which is housed in the hollow cylindrical body (1), and a lever (9) for manual operation of the pumping member (14). The pumping member includes a tubular element (26) extending through the cup-shaped diaphragm, the tubular element (26) having a valve member (30) for closing and opening its orifice (31) and being connected to a pipe (29) extending into a container (5). The cup-shaped diaphragm of the pumping member (14) has a continuous flexible lip (23) formed around its periphery, and being positioned within the channel (20) in order to close and open the orifice (21).

Description: The present invention relates to a pump for dispensing liquids, of the type described in the pre-characterising portion of claim 1. Pumps for dispensing liquids of the type specified above are known in the art. Examples of these pumps are described in patents US-A-4,138,038 and US-A-3,995,774. The basic problem encountered in known liquid-dispensing pump structures of the type specified above relates to the tortuous nature of the passageways for the liquid through the pumping member, which cause considerable pressure losses and thus appreciably reduce the efficiency of the pumps which, in any case, is limited owing to the very nature of small hand-operated pumps. Another problem which is encountered in known pump structures relates to the poor functional capacity of the valve members in the pipe for drawing the liquid from the container and for supplying it to the delivery duct. In known structures, these valve functions are performed by respective portions of a single annular lip of the cup-shaped diaphragm of the pumping member, these portions having to be deformed in opposite directions during each stage of the operation of the pump in order to draw liquid from the container and to supply liquid to the delivery pipe, respectively, whilst belonging to the same structural element of the diaphragm. This leads to warping of the portions of the lip which are intended to operate as valve elements with consequent loss of sealing capacity and, in the final analysis, with a loss of efficiency of the pump. The object of the present invention is therefore to provide a hand-operated pump structure for dispensing liquids having improved valve devices the efficiency of which is maintained in the long term and in which tortuous paths are not created for the passage of the liquid to be dispensed, with the overall result of better pumping efficiency. A further object of the present invention is to provide a very compact pump structure with a limited number of components all of which can be produced by moulding. From US-A-3,749, 290 a manually actuated triggen pump is known according to the pre-characterising of claim 1. The above-mentioned objects are achieved by a pump of the type mentioned above, which is characterized according to the characterising portion of the appended Claim 1. The invention will now be described in greater detail with reference to an embodiment illustrated in the appended drawings, in which: Figure 1 is a perspective view of the pump with its cap, Figure 2 is a vertical section through the body of the pump fixed to the container of liquid to be dispensed, with the pumping members in the rest position, Figure 3 is a sectioned view similar to that of Figure 2 with the pumping members at the end of their travel upon completion of the dispensing of a dose of liquid, Figure 4 is a sectioned view similar to those of Figures 2 and 3 with the pumping members in an intermediate stage of the drawing of the liquid from the container, Figure 5 is a perspective view showing the hollow cylindrical body of the pump alone, Figure 6 is a plan view of the cylindrical body of Figure 5, Figure 7 is a section taken on the line VII-VII of Figure 6, Figure 8 is a perspective view of the operating lever of the pump, Figure 9 is a perspective view of the pumping member with its tubular elements, Figure 10 is a perspective view of the means for engaging the pump on the container of liquid to be dispensed. With reference to the drawings, the hollow cylindrical body of the pump is generally indicated 1, the boat-shaped cap of the pump is indicated 2, and a threaded ring for screwing the pump onto the neck 4 of a container 5 of liquid to be dispensed through the end 6-of a delivery duct 7 is indicated 3. The trigger-like end of a lever 9 mounted for pivoting on a pin 10 carried by an axial rib 1a of the cylindrical body 1 is indicated 8. The other end 11 of the lever 9, which is positioned in the cavity 12 of the hollow cylindrical body 1, is formed with two parallel prongs 11a, as can best be appreciated from Figure 8. The end 11 with its prongs 11a is in contact with the outer surface 13 of a cup-shaped pumping member 14 the cavity of which faces towards the end 1b of the cylindrical body 1, defining a pumping chamber 15. As can best be seen in detail in Figure 9, the pumping member 14 is constituted by a resiliently flexible diaphragm and has, on its outer surface, a flange 16 which engages in an annular groove 17 of the body 1, in which it is firmly anchored by underlying ledges 18 integral with the body 1. At the end 1b, the body 1 forms a cylindrical chamber 19 around which there is an annular channel 20. This channel is in communication with the duct 22 of the delivery element 7 by means of the orifice 21, as well as with the cavity 15 of the pumping member 14. A flexible lip 23 of the pumping member 14, projecting from the circular rim 24 thereof, is positioned in the annular channel 20. The circular rim 24 bears on the wall 25 of the body 1 which defines not only the groove 17 in which the flange 16 engages but also the annular channel 20 the inner wall of which is indicated 25a. The axial extent of the annular lip 23, which normally bears on the wall 25a when the chamber 15 is full of liquid, is such as not to obstruct the orifice 21 of the delivery duct 22 completely. A tubular element 26, fixed to the diaphragm of the pumping member 14 in a position coaxial with the body 1 and with the cylindrical chamber 19 has, at one end, a portion 27 extending inside the cavity 15 of the pumping member and, at the other end, a portion 28 extending towards the container 5. A conventional suction pipe 29 immersed in the liquid inside the container 5 is fitted on the portion 28. The portion 27 of the tubular element 26 has a plate 30 disposed across the orifice 31 and connected to the rim thereof for a portion of its circumference, about which portion the plate 30 can thus move angularly and perform the function of closing and opening the orifice. The plate 30 has a small radial projection 32 which is intended to interfere with the internal wall 19a of the chamber 19 during the operation of the pump. The diameter of the cylindrical chamber 19 is in fact substantially equal to and, in any case, no smaller than the diameter of the portion 27 of the tubular element 26. The axial extent of the chamber 19 is no less than the axial length of the portion 27 which therefore behaves as a piston relative to the chamber. The means for engaging the cylindrical body 1 on the neck 4 of the container 5 is constituted, as already mentioned above, by a screw-threaded ring 3. As can be appreciated from Figure 10, the ring 3 has a diaphragm 33 with an axial hole 34 through which the portion 28 of the tubular element 26 which is fixed to the pumping member 14 extends and is engaged for sliding. The ring 3 has a collar 35 around which there is an annular projection 36; this projection engages with the steps 37 provided inside the hollow cylindrical body 1. The cylindrical body, together with the pump, is fixed firmly and removably to the container 5 by the screwing of the ring 3 onto the neck 4 of the container and the engagement of the projection 36 with the steps 37. The pump operates in the following manner. The pumping member 14 is considered to be in the position shown in Figure 2, and the chamber 15 may be considered to be full of liquid to be dispensed. If the trigger 8 is squeezed, the prongs 11a, between which the tubular element 26 is disposed, compress the diaphragm of the pumping member 14 pressurizing the liquid which is in the chamber 15 and at the same time also in the cylindrical chamber 19. The rise in pressure causes the plate 30 to fit tightly against the orifice 31 of the tubular element 26 and thus to close it; at the same time, the pressure causes the lip 23 to open out radially and to move away from the wall 25a of the channel 20 so as to allow the liquid to flow towards the orifice 21 and to be dispensed through the duct 22. The position and the shape adopted by the cup-shaped pumping member 14 upon completion of the dispensing of a dose of liquid is that shown in Figure 3. Upon release of the trigger 8, the resilience of the diaphragm of the member 14 causes expansion of the chamber 15 and produces a vacuum which returns the lip 23 to fit tightly against the wall 25a of the channel 20. At the same time, the plate 30 is raised, opening the orifice 31 and consequently drawing liquid from the container 5 through the pipe 29, and the tubular element 26. The lifting of the plate 30 from the rim of the orifice 31 is facilitated by the projection 32 which is engaged with friction on the surface 19a of the cylindrical chamber 19 in which the tubular element 27 slides like a piston. Upon completion of the suction stroke, approximately as shown in Figure 4, the chamber 15 is refilled with liquid ready to be dispensed in the manner described above. It can be appreciated from the foregoing that the valve members of the pump according to the invention are not subject to twisting movements which could compromise their functional capacity over time, and that the pumping member with its valve members can be moulded as a unitary component, as can the hollow cylindrical body, dramatically reducing the number of components, benefitting the cost of the device.

Claims: A pump for dispensing liquids of the type comprising a hollow, cylindrical support body (1) having an annular channel (20) formed at a first axial end (1b) of the body and open towards the internal cavity (12) of the body, a delivery duct (22) carried by the hollow cylindrical body (1) and projecting radially therefrom, the delivery duct (22) being in communication with the annular channel (20) by means of an orifice (21), engagement means (3) disposed at the other end of the hollow cylindrical body (1) for the connection of the pump to a container (5) of liquid to be dispensed, a pumping member (14) presenting a cavity facing the channel (20) and a surface (13) facing the means (3) for connection to the container (5) of liquid, and which is housed in the hollow cylindrical body (1), a flange (16) fixed to a diaphragm of the pumping member (14), projecting radially outwardly relative to the cavity (15), and connected peripherally to the internal wall (17) of the hollow cylindrical body (1) in order to anchor the pumping member (14) to the cylindrical body, a continuous flexible lip (23) formed around the diaphragm periphery, the lip (23) being positioned within the channel (20) in order to close and open the orifice (21) for access to the delivery duct (22), and a lever (9) mounted for pivoting about a pin (10) carried by the hollow cylindrical body (1), the lever (9) having a first end (11) disposed inside the cavity (12) of the hollow cylindrical body in contact with the surface(13) of the diaphragm of the pumping member (14) and a second end formed as a trigger (8) disposed outside the hollow cylindrical body (1), for the manual operation of the pumping member (14) in opposition to the resilient force due to the deformation of the diaphragm of the pumping member, characterized in that it includes the pumping member (14) in the form of a resiliently-flexible, cup-shaped diaphragm with a convex surface (13) cooperating with the first end of the lever, a tubular element (26) extending through the cup-shaped diaphragm of the pumping member (14) in a position coaxial with the hollow cylindrical body (1) and being axially guided inside the cylindrical body (1) between a not deformed position of the pumping member (14) and a deformed position of the pumping member (14), the tubular element (26) having a first end (27) having an orifice (31) and extending inside the cavity (15) of the cup-shaped diaphragm of the pumping member (14), and an opposite end (28), also having an orifice, and extending towards the container (5) of the liquid to be dispensed, the first end (27) having a valve member (30) for closing and opening its orifice (31), the opposite end (28) being connected to a pipe (29) extending into the container (5) of the liquid to be dispensed in order to draw the liquid in. A pump for dispensing liquids according to Claim 1, characterized in that the opposite end (28) of the tubular element (26) extends through an internal sleeve-shaped aperture provided in the engagement means (3). A pump for dispensing liquids according to Claim 1, characterized in that the orifice (31) of the tubular element (26) first end (27) is disposed at a level over the pumping member (14) flange (16). A pump for dispensing liquids according to Claim 1, characterized in that the tubular element (26) extending through the cup-shaped flexible diaphragm of the pumping member (14) is formed integrally with the diaphragm. A pump for dispensing liquids according to Claims 1 and 4, characterized in that the valve member carried by the end (27) of the tubular element (26) which is disposed inside the cavity (15) of the diaphragm is constituted by a circular plate (30) which is disposed across the orifice (31) in order to close and open the tubular element (26) and is connected to the rim of the orifice for a portion of its circumference, the plate (30) being angularly movable about the said portion of the circumference in order to close and open the orifice (31). A pump for dispensing liquids according to Claim 5, characterized in that the plate (30) has at least one radial projection (32) on its peripheral edge. A pump for dispensing liquids according to Claims 1 to 6, characterized in that the hollow cylindrical body (1) has a cylindrical chamber (19) positioned coaxially with the annular channel (20) and with the tubular element (26), the cylindrical chamber (19) having a diameter substantially equal to the outside diameter of the plate (30) for closing and opening the orifice (31) of the tubular element (26) and an axial length not less than the length of the portion (27) of the tubular element which extends within the cavity (15) of the cup-like diaphragm of the pumping member (14).

Inventors: BATTEGAZZORE PIERO, BATTEGAZZORE, PIERO
Applicants: GUALA DISPENSING SPA, GUALA DISPENSING S.P.A.
Application year: 1998
Main classification: B05B11
IPC codes: B05B11, B67D7