CROSS-REFERENCE TO RELATED APPLICATIONS This application claims benefit of priority of1/5,provisional application, serial number 60/018,663, filed May 30, 1996.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

BACKGROUND OF THE INVENTION

The present invention relates to a filling system for use in a packaging machine. More particularly, the present invention relates to a filling system which utilizes a multi-stage linear valve actuator to provide for different filling rates and volumes.

In the past, packaging machine systems have been proposed, such as disclosed in International Publication Number WO 96/09957, entitled "Packaging Machine System for Filling Primary and Secondary Products Into A Container," published April 4, 1996. The '957 International Publication claims priority from a U.S. patent application, Serial No. 08/315,246, filed September 29, 1994. International Publication No. WO 96/09957 and U.S. Application 08/315,246 are expressly incorporated

A need remains within the industry for an improved product filling mechanism which has enhanced filling accuracy and which is able to fill containers of differing volume sizes.

BRIEF SUMMARY OF THE INVENTION It is an advantage of the present invention to provide a multi-step secondary outlet valve assembly to improve filling accuracy for containers of differing volumes.

It is a further advantage of the present invention to provide a multi-step secondary outlet valve assembly which provides an even filling profile. It is yet a further advantage of the present invention to provide a multi-step secondary outlet valve assembly which affords better accuracy when combining two products, such as cream and skim milk, thereby affording a better end product. These and other advantages of the invention are achieved in a packaging machine for filling a container with a primary product and a secondary product comprising a primary fill pipe having an interior extending to an outlet. The machine also has a secondary fill pipe arranged within the interior of the primary fill pipe. The secondary fill pipe has an opening near the outlet of the primary fill pipe. A multi-stage valve is arranged at the opening of the secondary fill pipe, and a linear valve actuator is operatively connected to the valve to open the valve in multiple discrete stages with respect to the opening of the secondary fill pipe, thereby controlling secondary product flow therethrough.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

Fig. 1 illustrates a perspective view of a filling mechanism according to the present invention;

Fig. 2 illustrates a perspective exploded view of a filling mechanism according to the present invention; Fig. 3 illustrates a side sectional view of a filling mechanism according to the present invention taken along line 3-3 in Fig. 1;

Fig. 4A illustrates a side sectional view of an upper most portion of the filling mechanism of Fig. 3;

Fig. 4B illustrates a side sectional view of an intermediate section of the filling mechanism of Fig. 3;

Fig. 4C illustrates a side sectional view of a lower end portion of the filling mechanism of Fig. 3 when in a closed position;

Fig. 5 illustrates a side sectional view of the lower end portion of the filling mechanism of Fig. 3 when opened to a first step or stage; and Fig. 6 illustrates a side sectional view of the lower end portion of the filling mechanism of Fig. 3 when opened to a second step or stage.

DETAILED DESCRIPTION OF THE INVENTION Fig. 3 generally illustrates a filling mechanism (denoted by the reference numeral 2) according to a preferred embodiment of the present invention. The general structure of the filling mechanism 2 is set forth and described in the above referenced co-pending U.S. application (Serial No. 08/315,246, filed September 29, 1994) and International Publication (WO 96/09957, published April 4, 1996). Since the '246 U.S. Application and '957 International Publication have been incorporated by reference, the details of the filling mechanism are not described hereafter. Generally, the filling mechanism includes an inlet 4 for secondary product which communicates with a fill pipe 6. The fill pipe 6 has an open lower end 8 (Fig. 4C) . The fill pipe 6 receives a stem 10 along its interior. The upper end of the stem 10 is securely engaged by a linear valve actuator (generally denoted by reference 12 in Fig. 3) . The stem 10 is driven linearly and reciprocally along its longitudinal axis by the actuator 12. The linear actuator 12 may be on'e of several known constructions, such as a mechanically driven actuator, pneumatically driven actuator, hydraulically driven actuator and the like. In the preferred embodiment, the actuator is hydraulically driven. The linear valve actuator 12 may be extended to multiple discrete steps or stages. For instance, the linear valve actuator 12 may represent a two-step/stage

actuator which is drivable between a retracted position, a first extended position and a second extended position.

Optionally, the actuator 12 may include more than two steps or stages, depending on the needs of the filling mechanism.

Fig. 4C illustrates a lower end portion of the filling mechanism 2, while the actuator 12 is retracted, whereby the stem 10 sealably closes the open end 8 with the valve 18.

Fig. 5 illustrates the lower end portion of the filling mechanism 2, while the linear actuator 12 is extended to the first step or stage. When extended to the first step, the actuator 12 drives the stem 10 downward by a first distance or valve stroke to a first position. When at the first extended position, an opening 16 is provided between the valve 18 and the lower end 8 of the fill pipe 6. The width of the opening 16 is denoted D,.

Fig. 6 illustrate the lowered portion of the filling mechanism 2 while the actuator 12 is extended to the second step or stage. When extended to the second step or stage, the actuator 12 drives the stem 10 downward to a second extended position. When at the second step, the opening 16 is widened to a width denoted D ₂ .

As explained above, the linear actuator 12 may include more than two steps and thus the opening 16 may be discretely varied by distances other than D, and D ₂ . The gap widths D, and D ₂ may vary depending upon the particular application.

By way of example only, the width D, may equal 4mm while the width D ₂ may equal 10mm.

By utilizing a linear actuator 12 which is extendable to multiple steps, the preferred embodiment of the present invention provides more accuracy when filling containers of differing volumes, thereby providing a more even filling profile.

While particular elements, embodiments and applications of the present invention have been shown and described, it will be understood, of course, that the invention is not limited thereto since modifications may be made by those skilled in the art, particularly in light of the foregoing teachings. It is, therefore, contemplated by the appended claims to cover such modifications as incorporate those features which come within the spirit and scope of the invention.