Metering pump

Abstract

Disclosed is a metering pump comprising a housing that extends from an inlet region to an outlet and surrounds a piston which is urged into a starting position by a compression spring. In the metering pump the stop limiting the lifting stroke of the piston is formed by the lower end of the piston coming in contact with the inlet portion.

Claims

1. A metering pump, comprising: a housing which extends from an inlet portion to a dispensing opening and which envelops a piston which is loaded by a compression spring in a starting position and which is moveable against a spring force of the compression spring into an end position, wherein a lift stroke of the piston is defined by a stop at the end position and the piston includes a piston plunger which is enveloped by a piston element which is movably arranged on the piston plunger; wherein the inlet portion includes a disc-shaped inlet valve that includes a circumferential seal disc being connected with a central seal plug via horizontal ribs with the circumferential seal disc being clamped in the housing, and wherein the stop at the end position of the lift stroke of said piston is defined by the piston abutting the circumferential seal disc of the disc-shaped inlet valve.

2. The metering pump according to claim 1, wherein the compression spring is arranged about a hollow piston rod provided by the piston.

3. The metering pump according to claim 1, wherein the disc shaped inlet valve includes a spring-biased sealing plug and an outer sealing disc.

4. The metering pump according to claim 1, wherein a one-piece sleeve is inserted into the housing and supports the piston.

5. The metering pump according to claim 4, wherein the one-piece sleeve is at least one of interlocked in the housing and pressed into the housing.

6. The metering pump according to claim 1, wherein the piston plunger includes a lower expansion.

7. The metering pump according to claim 1, wherein the plunger has plural pass through openings.

8. The metering pump according to claim 4, wherein a preassembled mounting unit comprises the piston, the compression spring and the one-piece sleeve.

9. A metering pump comprising: a housing which extends from an inlet portion to a dispensing opening and which envelops a piston which is loaded by a compression spring in a starting position and which is moveable against a spring force of the compression spring into an end position, wherein a lift stroke of the piston is defined by a stop at the end position and the piston includes a piston plunger which is enveloped by a piston element which is movably arranged on the piston plunger; wherein the inlet portion includes a disc-shaped inlet valve that includes a circumferential seal disc being connected with a central seal plug via horizontal ribs with the circumferential seal disc being clamped in the housing; and wherein the stop at the end position of the lift stroke of the piston is defined by a base portion of the housing from which the inlet portion extends.

10. The metering pump of claim 1, wherein the housing includes a base portion having a circumferential edge which clamps the circumferential seal disk.

11. The metering pump according to claim 4, wherein the one-piece sleeve includes radial bars in an inner portion which support the piston.

12. The metering pump according claim 4, wherein the lift stroke of the piston is further defined by a stop at the starting position, wherein the stop at the starting position is defined by the piston plunger contacting the one-piece sleeve via the piston element arranged therebetween.

13. The metering pump according to claim 12, wherein a lower end of the one-piece sleeve is configured to contact the piston element.

14. The metering pump according to claim 13, wherein the piston plunger includes a lower expansion that contacts an inner annular sealing skirt of the piston element and the piston element contacts the one-piece sleeve through an outer annular sealing skirt of the piston element in the stop at the starting position.

15. The metering pump according to claim 1, wherein the piston and the piston plunger comprise a plastic injection molding and wherein a material of the piston comprises a soft material providing a seal between the piston and the piston plunger and a material of the piston plunger comprises a material that is harder than the material of the piston.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages of the invention are evident from the subsequent description provided with reference to the drawing figure, wherein:

(2) FIG. 1 illustrates a metering dispenser in a starting position according to a first embodiment wherein the metering dispenser is configured for a first metering volume;

(3) FIG. 2 illustrates a longitudinal sectional view according to FIG. 1 in a lower end position;

(4) FIG. 3 illustrates a depiction according to FIG. 1 wherein the housing of the metering pump has a smaller volume;

(5) FIG. 4 illustrates a longitudinal sectional view similar to FIG. 2; and

(6) FIG. 5 illustrates a suitable inlet valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(7) According to FIG. 1 the metering pump 1 includes a tubular housing 2 which extends along the vertical axis between a lower inlet portion 2a and an upper dispensing opening 2b in order to feed the product from a non-illustrated (lower container). An axially moveable piston 4 is arranged in the housing 2 wherein the piston 4 can be depressed within a support cylinder 3 between the starting position (FIGS. 1 and 3) and an end position proximal to the inlet 2a (FIGS. 2 and 4) against the compression spring 5. The compression spring 5 arranged on an outside at a central feed path is supported in an upward direction at a flange 6 which is formed at the piston 4 or its hollow piston rod 4f. A flange 6 can be furthermore provided for an exact support of the piston 4 during depressing (c.f. FIG. 2) wherein the cylinder 3 thus includes radially inward oriented bars 9a in order to minimize friction. Thus additionally a cap nut or a snap closure 2c are externally placed onto the housing 2 in order to connect the metering pump 1 with the container for the product to be metered thus by simply pressing the snap closure 2c onto the housing.

(8) The housing 2 and the lower end 4e of the piston 4 define a metering chamber 7 into which the piston can penetrate. The volume of the metering chamber 7 is thus defined by the amount of product to be fed as evident from a comparison of the relative long housing of FIG. 1 and FIG. 2 with the relative short housing of FIGS. 3 and 4. The piston 4 is advantageously identically configured in both embodiments and can respectively release a ventilation bore whole 7a in the right facing wall of the housing 2 when being depressed. However in the respective starting position (FIGS. 1 and 3) the ventilation bore whole 7a is sealed by the piston 4. The piston 4 or its piston rod 4f is configured hollow in a center in order to facilitate feeding the product to the upper dispensing portion 2b. A disc shaped inlet valve 8 can be provided in the inlet portion 2a wherein the disc shaped inlet valve 8 is safely pressed in contact by the lowest portion 4e of the piston 4 and thus always closed in a sealing manner. Should the inlet valve 8 have moved for example when suctioning the product or already during assembly it is exactly realigned in its sealing seat?

(9) A sleeve 9 is inserted into the housing about the compression spring 5, advantageously attached with a press in edge 9b in the housing 2. The sleeve 9 is advantageously integrally configured in one piece, in particular as an injection molded plastic component. Radial bars 9a can be configured at an inner surface of the sleeve. A similar snap locking or clip connection is provided for the hollow piston 4, namely for its lower portion in the form of a plunger 4a, which has a flange shaped expansion 4b in a downward direction. Between this expansion 4b and the lower edge of the sleeve 9 a jacket shaped piston element 4c is arranged which is advantageously made from polyethylene so that plural sealing edges or portions are formed within the metering chamber 7. In particular the plunger 4a is made from a harder material than the concentrically arranged element 4c.

(10) Thus, it can be advantageously provided that the lower end of the sleeve 9a is used in the starting position according to FIGS. 1 and 3 as a stop for the piston element 4c. Thus the upper outer edge of the piston element 4c in FIG. 1 and also in FIG. 3 contacts an outer shoulder of the sleeve 9. When depressing the piston 4 the piston element 4c is moved along proximal to the inlet portion 2a but not moved into contact. Thus according to FIG. 1 the lower end of the piston 4 is arranged at a distance from the piston element 4c that is evident from FIGS. 1 and 3, wherein the gap thus formed is designated as 10. When depressing the piston 4 the piston 4c is moved along by the piston 4 with a certain amount of delay. Thus annular gap opens between the expansion 4b and an inner lower edge of the piston element 4c or the downward oriented tongue or annular inner sealing skirt 11 of the piston element 4c, wherein the product can be fed through the annular gap (dashed dotted line in FIG. 2). For this purpose the plunger 4a is formed hollow as well and advantageously includes plural pass through openings 4d so that depressing the piston 4 and thus opening the plunger 4a allows the product to flow through the open annular gap to the piston element 4c to the central dispensing opening 2b in the piston 4 or its piston rod. As evident from FIG. 1 the inner piston plunger 4a is supported at the piston element in the upper starting position, in particular by the tongue 11 and the additional tongue or annular outer sealing skirt 13 at a lower end of the advantageously one piece 9 which is advantageous for correct sealing.

(11) Thus, it is essential that the lower end 4e contacts the inlet portion 2a, in particular the inlet valve 8 or its sealing disc 8a or the seal plug 8b in order to realign the inlet valve 8 from a deviation. As evident from the figures the seal disc 8a is clamped in the housing, the circumferential edge 2a′ of the base portion 20 reaches over the seal disc 8a, wherein the seal disc 8a is connected with the central sealing plug 8b through the horizontal bars evident from the figures. Thus the sealing plug 8b is suspended spring loaded and can move under a negative pressure in an upward direction into an open position when the piston 4 moves up and is then moved back into its closed position according to the FIGS. 1 and 3 due to the sealing disc 8a being supported relative to the housing by the spring loaded suspension. Thus the expansion 4b engages a circumferential edge 2a′ of the base portion 20, like a bead. Simultaneously this stop provides the stroke limitation of the piston 4. FIG. 5 illustrates the inlet valve 8 in a perspective view. Advantageously however the illustrated circumferential sealing disc 8a is connected by bars with the sealing plug 8b, which yields a desired elasticity but also a suitable contact surface for the piston, in particular the piston plunger. In FIGS. 3 and 4 the expansion 4b is configured with a larger diameter so that the outer edge of the expansion 4b contacts the circumferential bead 2a′ at a face side in the end position. Also here misalignments of the sealing disc 8a or of the sealing plug 8b can be corrected, wherein an inward protruding housing shoulder can also be used as a stop instead of a bead, like circumferential edge 2a′.

(12) The second embodiment of the metering pump 1 illustrated in FIGS. 3 and 4 differs from the first embodiment (FIGS. 1 and 2, remainder of the configuration of the piston 4 remains the same) using a housing 2 that is shorter along the vertical axis and thus a smaller metering volume. For this embodiment the same components can be used which is advantageous for mass products of this type. Without manual actuation the piston 4 is also preloaded by the compression spring 5 in an upward direction into its starting position (FIG. 3 similar to FIG. 1). The piston element 4c advantageously made from an elastic polyethylene thus contacts a lower end of the sleeve 9 so that a sealing contact is provided in an outward direction. Only after depressing (FIG. 4) the bleed hole 7a is open. As recited supra the sleeve 9 has radially inward oriented bars 9a which provide low friction support but which also reduce wall thickness and thus material requirement for the sleeve 9.

(13) The piston 4 with its components 4a, 4b, 4c, the compression spring 5 and the sleeve 9 configured as a support cylinder thus advantageously form a mounting unit which can be used for different types of metering pumps 1 which differ e.g. with respect to a size of the metering chamber 7 like in both embodiments recited supra. This yields substantial cost savings. Additionally the metering pump 1 is particularly compact due to the proposed end stop in or at the inlet portion 2a and functional very safe due to the provided correction of misalignments of the inlet valve 8.