Actuating head of a double-acting pump for ejecting a product from a container

ABSTRACT

An actuating head () of a double-acting pump () for ejecting a product () from a container () includes an outlet duct () leading to an ejection opening (), wherein a closing piece () biased by a spring () is arranged in the outlet duct. The closing piece () directly seals the ejection opening () under the force of the spring () and the closing piece () releases as a result of the pressure exerted when actuating the double-acting pump () the flow of the product () through the outlet duct () and through the ejection opening () against the force of the spring (). For simplifying the construction and for avoiding the danger of contamination of the product, it is ensured according to the present invention that a first outlet duct section () following the ejection opening () is surrounded by a tube () in which the closing piece () is sealingly slideably guided and which is inserted in a bore () in the body of the actuating head (), wherein the bore () defines between itself and the tube () an annular space forming a second outlet duct section (), wherein the annular space is connected through a third outlet duct section () traversing the wall of the tube () to the first outlet duct section ().

INFORMATION

DETAILED DESCRIPTION OF THE INVENTION

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and its further developments will be described below in more detail with the aid of the enclosed drawings showing a preferred embodiment. In the drawing:

FIG. 1 is an axial sectional view of a double-acting pump with an actuating head according to the present invention on a container filled with product to be ejected, shown prior to the first actuation of the double-acting pump by means of the actuating head,

FIG. 2 is an axial sectional view of the double-acting pump and the container of FIG. 1, shown during a first actuation of the double-acting pump by means of the actuating head,

FIG. 3 is an axial sectional view of the double-acting pump and the container of FIG. 1, shown at the end of the first suction movement of the double-acting pump,

FIG. 4 is the same axial sectional view as FIG. 2, shown during a first ejection actuation, and

FIG. 5 is an axial sectional view of the double-acting pump in the same position as in FIG. 1, however, at the end of an ejection actuation.

DETAILED DESCRIPTION OF THE PREFERED EMBODIMENTS

The double-acting pump shown in the drawing is tightly fastened on the rim of the opening of a container through a sealing ring disc arranged between the pump and the container. The double-acting pump includes a hollow-cylindrical housing . The lower end of the housing can be blocked off by a check valve with a valve closing ball . In its lower position illustrated in FIG. 1, the valve closing ball is tightly seated on a valve seat .

Arranged in the housing is a hollow-cylindrical piston so as to be axially slideable and sealed against the inner side of the housing . The bore of the piston extends as a hollow piston rod integrally formed on the piston . The piston rod is slideable in an opening of an upper closing hood so as to be sealed relative the housing and container .

An actuating head of the double-acting pump is sealingly and tightly placed on the free end of the piston rod which protrudes out of the housing . An outlet duct, composed of outlet duct sections -, extends through the actuating head , wherein the outlet duct is connected to the bore . The outlet duct section is constructed as an annular space which is defined by the inner side of a bore in the body of the actuating head and the outer side of a tube which is tightly placed in the bore . The outlet duct section is a bore extending through the wall of the tube , wherein the bore opens into the outlet duct section which forms the inner space of the tube . The diameter of the tube becomes smaller toward its outer end with an ejection opening . Axially slideably arranged in the outlet duct section is a closing piece which is biased by a weak spring . The closing piece has a piston which seals against the inner side of the outlet duct section in the tube , wherein the piston has a piston rod which, in the closed position of the closing piece shown in FIG. 1, projects with an end portion tightly in the ejection opening . The portion of the piston rod adjacent the end portion has a greater diameter than the outlet opening and in the closed position of the closing piece rests with an inclined transition from the larger to the smaller diameter against the inner rim of the ejection opening under the force of the spring . The piston has a circumferential sealing lip which tightly rests as a result of its own elasticity against the inner side of the tube or the outlet duct section and which permits passage of a medium only in the direction toward the ejection opening , while blocking the chamber which contains the spring . The sealing lip is formed by a cup-shaped material. The closing piece is of a rubber-elastic material, particularly an elastomer material, with an excess dimension of the end portion of the piston rod relative to the diameter of the ejection opening .

In its non-actuated position according to FIGS. 1, and , the piston rests with a sealing lip arranged circumferentially at its free end tightly against the inner side of the housing . A collar surrounding the piston above the sealing lip serves for guiding the piston during its movement, however, a play remains between the collar and the inner side of the housing . A restoring spring , shown in broken lines, rests in the piston against the bottom of an annular space which is defined by the outer wall of the piston and a tube piece , on the one hand, and against a shoulder in the housing , on the other hand. The housing has at the end of a pressure space defined by the housing a step underneath of which the inner diameter of the housing is somewhat greater than the outer diameter of the sealing lip of the piston . An immersion tube protruding close to the bottom of the container is fastened in a connecting piece at the free lower end of the housing . Above the upper end position of the piston according to FIG. 1, the housing is connected through lateral slots to the inner space of the container above the maximum product level.

During the first actuation of the actuating head by manually exerting a pressure on its upper side, the piston moves against the force of the restoring spring in the space according to FIG. 2 in the direction toward the check valve , . The resulting pressure in the space , in the bore and in the outlet duct -causes the check valve , to be kept closed, on the one hand, and the sealing lip of the closing piece is pressed against the inner side of the tube or the outlet duct section defined by the tube , on the other hand. Consequently, the piston is displaced against the force of the spring and the end portion of the piston rod is pulled out of the ejection opening . In this situation, the air contained in the space , in the bore , in the outlet duct -and in the spring chamber can escape only partially through the ejection opening . After the manual pressure has been removed from the actuating head , the restoring spring presses the piston and the spring presses the piston back into the position illustrated in FIG. . The resulting negative pressure in the space , in the bore and in the outlet duct -causes the valve closing ball to be lifted off from its seat up to against the ribs formed above the ball in the housing . Simultaneously, the negative pressure causes a portion of the product contained in the container to be withdrawn from the container through the immersion tube and the open check valve , into the space , as illustrated in FIG. . The product is preferably paste-like, but can also be a liquid.

When the piston is once again pushed down by means of the actuating head , the check valve , is once again closed and the piston is pushed once again against the force of the spring into the position shown in FIG. . Simultaneously, the product is ejected out of the space through the bore , the outlet duct -and the ejection opening which is once again open, as illustrated in FIG. . The piston can be pressed with its sealing lip up to underneath the step . As soon as the sealing lip has traveled past the step , the pressure in the space is eliminated past the sealing lip and the collar of the piston and through the slots into the space of the container above the product level, so that no additional product is ejected. As a result, the product quantity ejected during each actuation is precisely metered.

During the return movement of the piston which follows the removal of the manual pressure on the actuating head , the piston once again draws a portion of the product from the container into the space , wherein the piton once again closes the ejection opening under the pressure of the spring , as illustrated in FIG. .

When the piston is once again pushed down from the position according to FIG. 5 into the position according to FIG. 4, once again a precisely metered product quantity is immediately ejected. The same occurs during each further actuation until the container is completely empty.

As shown in FIGS. 1, and , the outlet duct -is in the closed position of the closing piece completely closed off from the outside by the closing piece . Consequently, a product rest remaining in the outlet duct cannot come into contact with harmful germs, bacteria, viruses, etc., and with harmful materials, gases, etc. On the other hand, the open position of the closing piece shown in FIGS. 2 and 4 only lasts a short time. A product rest remaining in the outlet duct -would be mostly ejected during the product ejection and could not be contaminated, because the open position of the closing piece lasts only a short time.

The closing piece not only acts as a closing piece, but also as a pressure piston which, after the actuation of the actuating head , ejects any product remaining in the section of the outlet duct under the force of the spring and simultaneously blocks off the ejection opening . The portion of the piston rod having the greater diameter rests during the closing movement of the closing piece under the force of the spring with its shoulder surface extending from the larger to the smaller diameter additionally sealingly against the inner rim of the ejection opening . This simultaneously limits the closing movement of the closing piece .

On the one hand, the sealing lip facilitates the passage of air from the spring chamber into the outlet duct during the first actuation of the actuating head and, thus, a displacement of the piston against of the force of the spring . Therefore, essentially only the force of the spring has to be overcome by the product pressure during the product ejection. During the first actuation, any air which has penetrated from the spring chamber into the outlet duct would be mixed partially with the product quantity which has been ejected and the product quantity to be ejected during the next actuation. However, during the second and any following actuation, no further air would penetrate from the spring chamber into the outlet duct because its excess pressure has already been eliminated and the sealing lip permits the passage of air only in one direction and, thus, no additional penetration of air into the spring chamber . In the same manner, a penetration of the product through the sealing lip into the spring chamber is prevented. Since the sealing lip is constructed as a cup-shaped material, the sealing lip is additionally pressed by the product pressure against the inner side of the tube or the section of the outlet duct. Accordingly, the sealing lip ensures a particularly high sealing effect. Since the closing piece is of rubber-elastic material and because its end portion has an excess dimension relative to the inner diameter of the ejection opening , the end portion rests in the closed position of the closing piece particularly tightly in the ejection opening . This results in a particularly high sealing effect of the end portion in the ejection opening . Moreover, when the rubber-elastic material of the closing piece is a plastic material, the closing piece can be constructed in a simple manner as a single piece.

CLAIMS

1. Actuating head (12) of a double-acting pump (1) for ejecting a product (38) from a container (2), wherein the actuating head (12) has an outlet duct (13a-13d) leading to an ejection opening (16), wherein a closing piece (18) biased by a spring (17) is arranged in the outlet duct, wherein the closing piece (18) in its closed position directly seals off the ejection opening (16) under the force of the spring (17) and wherein the closing piece (18) releases the flow of the product (38) through the outlet duct (13a-13d) and through the ejection opening (16) as a result of the pressure occurring during actuation of the double-acting pump (1) against the force of the spring (17), wherein a first outlet duct section (13d) following the ejection opening (16) is surrounded by a tube (15) in which the closing piece (18) is sealingly slidingly guided and which is placed in a bore (14) in the body of the actuating head (12), wherein the bore (14) defines between itself and the tube (15) an annular space forming a second outlet duct section (13b), wherein the annular space is connected to the first outlet duct section (13d) through a third outlet duct section (13c), which traverses the wall of the tube (15).

2. Actuating head according to claim 1, wherein the closing piece (18) has a piston (19) which seals against the inner side of the outlet duct (13a-13d), wherein the piston (19) has a piston rod (20) which in the closed position of the closing piece (18) protrudes with an end portion (20a) tightly in the ejection opening (16).

3. Actuating head according to claim 2, wherein the portion (20b) of the piston rod (20) adjacent the end portion (20a) has a greater diameter than the ejection opening (16) and in the closed position of the closing piece (18) the portion (20b) rests against the inner rim of the ejection opening (16) under the force of the spring (17).

4. Actuating head according to claim 2 or 3, wherein the piston (19) has a circumferential sealing lip (21) which permits passage of a medium only in the direction toward the ejection opening (16).

5. Actuating head according to claim 4, wherein the sealing lip (21) is formed by a cup-shaped material.

6. Actuating head according to one of claims 1 to 3, wherein the closing piece (18) is of a rubber-elastic material with an excess dimension of the end portion (20a) relative to the diameter of the ejection opening (16).

7. Actuating head according to claim 6, wherein the rubber-elastic material is a plastic material.

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