GB2090803A - Proportional valve for a material receiving device in a pneumatic conveyer - Google Patents

Abstract

A proportional valve 24 for controlling the pneumatic transportation of pulverant or granular material from a plurality of supply conduits 12 into a receiving device 10, the valve 24 having inlet tubes 34 connected to the conduits 12 and whose outlets communicating with a chamber 36 are controlled by valve members 50 operated by solenoids 46, the chamber 36 having an outlet 40 connected to a tube 34 which leads into the interior of the device 10. <IMAGE>

Description

SPECIFICATION Proportional valve for a material receiving device This invention relates to a proportional valve for a material receiving device.

In a number of industrial applications, for example the plastics industry, it is common practice to transport finely divided, granular or pulverant material from one or more storage bins, through one or more feed lines having a free end embedded in or otherwise in communication with respective materials to be transported to a material receiving device or loader by creating a vacuum in the receiving loader.

The resultant air flow occurring due to the vacuum is through the material and the one or more feed lines and entrains the material in the airstream flowing to the receiving loader.

The airstream carrying the entrained material is deposited in the receiving loader while the air is withdrawn therefrom by a vacuum pump. After the receiving loader has been loaded and the vacuum discontinued, the material deposited therein is subsequently discharged into a material receiving compartment of any suitable apparatus such as a processing hopper or a machine which subsequently processes the material.

In many of these applications it is often necessary or desirable to mix two or more or such finely divided granular or pulverant materials as the materials are being supplied to the receiving loader for subsequent discharge to the processing apparatus. For example, in the moulding of various industrial and commercial articles from resinous materials, it may be necessary to mix two different plastics to form a composite plastics material of given characteristics. Precision control of proportions and thorough mixing are often required.

One manner of providing such a mixture would be to premix substantial quantities of differing resinous materials for direct deposit in a storage bin for subsequent vacuum transportation to a material receiving device. However, such a premixing arrangement may not be desirable for a variety of reasons, for example: inefficiencies resulting from the necessity to premix; inconsistency caused by the gravitational settlement of lighter weight materials within the bin; and other processing equipment may be in operation and may be fed from the same basic storage bins at the same time with different proportions required or even with different materials entailed.

In applications such as those discussed above, the mixing of granular or pulverant material which is discharged to the processing machine is often accomplished at the material receiving loader. In one form of such an arrangement, for example as is illustrated in U.S Patent No. 3,780,991, the material receiving loader is arranged to have materials delivered thereto from discrete storage bins with the material feed to the receiving loader being controlled on a time basis to obtain the requisite proportions. In such an application, the flow of materials into the receiving loader is conventionally controlled by a valve arrangement which is rendered operable by a coordinated control system which activates the valves in timed sequence.Thus, with such a valved arrangement, material may be deposited within the receiving loader in a layered fashion or, particularly if an equal timed feed of differing materials is to be conveyed simultaneously (i.e., a predetermined mixture of virgin and regrind granulated plastics), the materials may be mixed during the simultaneous valved introduction of the material into the receiving loader.

Valve arrangements such as those discussed above and as are illustrated in U.S. Patent No. 3,780,991, often suffer from a number of operational and/or maintenance problems.

For example, such valving arrangements are often positioned within the hopper portion of the receiving loader and, as such, the replacement or cleaning thereof is time consuming and relatively complex. Furthermore, the interior placement of such valving arrangements dictates that any provision for adjustability thereof, other than timing, is complex and not feasible from an operations standpoint. Still further, such prior valving arrangement, while perhaps being suitable for a timed layer loading of a receiving device with granulated or powdered materials, have generally proved to be deficient in providing an adequate mixing action for discrete materials which are being simultaneously introduced into the receiving loader.

An additional form of a prior art device which provides for the simultaneous or timed introduction of two or more materials into a receiving loader is illustrated in U.S. Patent No. 3,635,377 and includes a selectively moveable partition or divider within the hopper portion of the receiving loader for dividing the hopper into discrete chambers. While this arrangement has proved adequate in many instances; it does, however, suffer from several deficiencies, for example: poor mixing action for the materials are not evenly dispersed over the entire inner periphery of the hopper; significant down time when it is desired to change the receiving loader to enable it to receive less or more than two materials; and such an arrangement is difficult to clean and maintain.

According to the present invention there is provided a proportional valve means for use with a vacuum material receiving device wherein a granular or pulverant material is transported, in suspension with a flowing airstream, from a plurality of discrete sources, through such valve means and into a hopper portion of such a receiving device, said valve means comprising a body portion having wall portions which define a chamber therewithin; said body portion including a discharge opening through one of said wall portions and capable of being carried by said receiving device externally thereof in a manner that said discharge opening establishes constant open communication between said chamber and a said hopper portion; a plurality of actuatable valve assemblies carried by said body portion and operable to provide selective communication between respective ones of such discrete sources and said chamber; and the areas of communication of said valve assemblies with said chamber being meet from said discharge opening in a manner to provide a tortuous flow path from said areas of comrnuniátion to said discharge opening.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying dravrfings, in which: Figure 1 is E3 schematic sckeri9aaaie: illustration, partially in section, of a material receiving device or loader provided with a valve means con structed in accordance with the present invention; Figure 2 is an enlarged longitudinal view, partially in section, of the proportional valve means illustrated in Fig. 1 and which is constructed in accordance with the principles of the present invention; and Figure 3 is a plan view of the propotional valve means of the present invention as viewed on lines 3-3 of Fig. 2.

Fig. 1 illustrates a material receiving device or loader 10 which is incorporated in a vacuum conveyor system of the type for proportional feeding of finely divided granular of pulverant plastics material through a plurality of feed lines 12 from respective bins therefor (not shown) to a moulding press or other processing equipment 14.

As is shown in Fig. 1, the loader 10 comprises a hopper 1 6 having a cylindrical upper section 18 mounted upon frusto-conical lower section 20. The frusto-conical section 20 communicates at the lower end thereof with a hopper or the like of the processing equipment 14. Communication between the loader 10 and the processing equipment 14 is selectively controlled in any suitable manner, for example by an inverted cup-shaped moveable valve member 22 which is positioned adjacent the lower end of the frusto-conical section 20. Section 20 is rendered operable by a suitable selectively actuatable device for the control of the discharge of the loaded granular materials from the loader 10 to the processing equipment 14.

Suitable vacuum means (not shown) are provided in known communication arrangements with the loader 10 to create a vacuum therein to pneumatically suspend the granular material in the slowing airstream and draw such granular materials from the bins through the feed lines 12, thence through a proportional valve means 24 of the present invention and thence into the hopper 1 6 of the receiving loader 10.

Inasmuch as the invention herein is primarily directed to the configuration and utilization of the proportional valve means 24 and, further, that the general configuration and operation of vacuum material receiving devices or loaders are well known in the art, a detailed description of the components and operation of elements of loader 10, other than the valve means 24, is not necessary to one skilled in the art for a full understanding of the invention herein. For a further description of gen eral configuration and operational parameters of vacuum system material receiving devices or loaders, reference is hereby made to U.S.

Patent Nos. 3,273,943; 3,635,377; and 3,780,991.

As is best illustrated in Figs. 2 and 3, the proportional valve means 24 comprises: a generally rectangular body member 26 which includes a valve receiving and mixing chamber 28 therewithin; a plurality, as shown two, solenoid operable axial valve assemblies 30 carried by the body member 26; and a plurality, as shown two, inlet tubes 32 which are carried by the body member 26 in a manner that each tube 32 has one end thereof received within the chamber 28 and the other end thereof being spaced from the body member 26.

In the assembled position, the proportional valve means 24 is externally carried by the hopper 16 adjacent an upper end portion of cylindrical section 1 8. The arrangement for mounting the valve means 24 to the hopper 16 may be accomplished in any suitable manner. As shown in Fig. 1, cylindrical section 18 includes a tangential hopper inlet tube 34 adjacent the upper end thereof which openly communicates at one end thereof with the interior of the hopper 1 6 and extends outwardly therefrom. One wall section 36 of the body member 26 includes an outer annular portion 38 which is dimensioned to be received within the outer end portion of the hopper inlet tube 34 (see Fig. 2). The annular portion 38 includes a bore 40 therethrough to thus provide open communication between the mixing chamber 28 and the interior of the hopper 16. Annular portion 38 is maintained in operational position in any suitable manner; for example, by fastening means (not shown) which extend radially between adjacent peripheral portions of the tube 34 and the portion 38.

At this point, it is important to note that the proportional valve means 24 is mounted externally of the interior of hopper 1 6. Thus cleaning or maintenance of the valve means 24 is greatly simplified over prior art valve means or proportional feed arrangements which were positioned within the hopper 1 6.

Furthermore, the exterior location and structure of the valve means 24 permits the inclusion of a transport chamber wall section 42 if desired. Wall section 42 is of any suitable transparent material, for example a hard plastics material, and is best shown in Figs. 2 and 3 as being of a generally rectangular configuration and being positioned with suitable fastening means (not shown) to provide a wall of chamber 28 which is directly opposite the wall section 36. With the inclusion of such a transparent wall section, an operator may readily view the interior of the chamber 28 and thus quickly determine its cleanliness and also wheiher or not the axial valve assemblies 30 are operating properly.Thus, through the use of the readily accessible transparent wall 42, maintenance time will be reduced by not unnecessarily disassembling the valve means 24 for the cleaning thereof and also product intergrity will be increased for the operator is now able to readily ascertain the operating condition of the axial valve assemblies 30.

As is best illustrated in Fig. 3, the pair of valve assemblies 30 are carried by wall section 44 of the body member 26 in side-byside relationship. As shown, the wall section 44 is one of the long length wall sections of the body member 26 which are at right angles to the wall section 36. The pair of tubes 32 are suitably carried in side-by-side relationship by the wall section 45 of body member 26 in respective coaxial alignment with the valve assemblies 30. The outer end portion of each tube 32 is suitably secured to a respective feed line 1 2 to thus provide means for communicating the storage bins with the proportional valve means 24.

Each valve assembly 30 comprises a solenoid operable cylindrical portion 46 carried on the exterior wall section 44 which, upon the actuation thereof, is operable to axially reciprocate a rod portion 48 which extends axially therefrom into the chamber 28. The free end of each rod portion 48 carries a plug portion 50 thereon.The stroke of the rod portion 48 is such that: upon the inward reciprocation thereof, the suitably dimensioned plug portion 50 is in sealing engagement with the inner end of an adjacent inlet tube 32 to discontinue the communication between the respective feed line 12 therefor and the valve means 24; and upon the outward reciprocation thereof, the plug portion 50 is spaced from the inner end of inlet tube 32 and, thus, communication between the respective feed line 1 2 therefor and the valve means 24 is established. The construction and operation of the axial valve assembly 30 may be of any suitable type and the control and sequencing therefor would be well known to anyone skilled in the art; for example, see U.S. Patent No. 3,780,991 for a more detailed discussion of sequencing arrangements for proportional valve means.

With a configuration as discussed hereinabove, the proportional valve means 24 provides a structure which will selectively control the discrete feeding of a plurality of supplies of granular material to the receiving loader 10 in a simultaneous manner or, if preferred, in a sequential manner. In a simultaneous feeding, appropriate signals are relayed to both valve assemblies 30 such that communication between both feed lines and the chamber 28 are simultaneously established by the outward movement of the respective rod portions 48 thereof. At this point, it is important to note that the invention herein provides that the point of introduction of the granular material from the inlet tubes 32 into the chamber 28 is offset at right angles with respect to the point of exit of such materials from the valve means 24 through the bore 40.Accordingly, a tortuous path is created which results in a rigorous mixing action of the material exiting from each inlet tube 32 occurring within the chamber 28 prior to the exit therefrom. Thus, an intermixed material comprised of the discretely transported materials will be uniformly deposited within the hopper 1 6. On the other hand, when layered feed to the receiving loader 10 is preferred, appropriate signals are sequentially relayed to the valve assemblies 30 such that communication between the feed lines 1 2 and the chamber 28 is established in a timed sequential manner and, as such, the granular materials will be deposited in hopper 16 in a discrete layered fashion.

The embodiment described herein is the presently preferred embodiment of a proportional valve means for a vacuum operable material receiving device which is constructed in accordance with the principles of the present invention; however, it is to be understood that various modifications may be made to the embodiment described herein by those knowl edgeabie in the art without departing from the scope of the invention as is defined by the appended claims. For example: body member 24 may be enlarged to provide room for an additional plurality of proportional valve means and, thus, the ability to proportionally control a respective plurality of additional feed lines 1 2 to the receiving loader 10; the inlet tubes 32 may be modified to permit the selective introduction of reducing sections to thus provide for a simple mechanical flow adjustment rather than relying only on timed sequencing; body member 26 may be provided with a formed flange adjacent wall section 36 for direct bolting of the valve means 24 to the hopper 1 6; interior baffles may be included within the chamber 28 to further increase the tortuous path from the inlet tubes 32 to the bore 40; and the like.

Claims (9)

1. A proportional valve means for use with a vacuum material receiving device wherein a granular or pulverant material is transported, in suspension with a flowing airstream, from a plurality of discrete sources, through such valve means and into a hopper portion of such receiving device, said valve means comprising a body portion having wall portions which define a chamber therewithin; said body portion including a discharge opening through one of said wall portions and capable of being carried by said receiving device externally thereof in a manner that said discharge opening establishes constant open communication between said chamber and a said hopper portion; a plurality of actuatable valve assemblies carried by said body portion and operable to provide selective communication between respective ones of such discrete sources and said chamber; and the areas of communication of said valve assemblies with said chamber being offset from said discharge opening in a manner to provide a tortuous flow path from said areas of communication to said discharge opening.

2. A proportional valve means as claimed in claim 1, in which said areas of communication are through another wall portion of said chamber which extends along a plane which is substantially normal to a plane extending along said one of said wall portions.

3. A proportional valve means as claimed in claim 2, in which each of said valve assembly include a tube portion and a selectively reciprocal valve portion; said tube portion being carried by said another wall portion and said valve portion being carried by still another wall portion; and said still another wall portion being directly opposite said another wall portion.

4. A proportional valve means as claimed in claim 3, in which the valve and tube portions of respective valve assemblies are in coaxial alignment, each of said tube portions openly communicate with a respective discrete source one end thereof and extend into said chamber therefrom.

5. A proportional valve means as claimed in claim 4, in which said valve portions are selectively operable to establish and discontinue communication between said chamber and respective ones of such discrete sources by sealing and unsealing the respective ends of said tube portions which are opposite said one end thereof.

6. A proportional valve means as claimed in any of claims 1 to 5, in which yet another wall portion of said chamber, which is opposite said wall portion, is of a transparent material.

7. A proportional valve means as claimed in claim 6, in which said yet another wall portion is of a rigid plastics transparent material.

8. A proportional valve means substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. A material receiving device provided with a proportional valve as claimed in any preceding claim.