Flow limiting and variable frequency drive apparatus for limiting flow to selected level

Abstract

A controlled, variable speed vacuum pump with a flow limiter connected to the suction head of the vacuum pump conveys granular plastic resin material from a supply to receivers retaining and dispensing resin when needed by a process machine.

The following is claimed: 
     
         1 . Apparatus for conveying granular plastic resin material from a resin supply preparatory to molding or extruding that material into finished or semi-finished plastic parts, comprising:
 a. at least one receiver for receipt and temporary storage of the granular plastic resin material preparatory to the molding or extrusion;   b. a vacuum pump;   c. a first conduit for conveyance of the granular plastic resin material from the supply to the receiver;   d. a second conduit for conveyance of a vacuum/air stream from the receiver to the vacuum pump;   e. a variable speed drive for the vacuum pump.   
     
     
         2 . Apparatus of  claim 1  further comprising a microprocessor for controlling speed of the drive for the vacuum pump. 
     
     
         3 . Apparatus of  claim 2  further comprising a sensor for sensing at least one flow parameter in the second conduit, connected to the microprocessor for furnishing flow parameter information thereto. 
     
     
         4 . Apparatus of  claim 2  further comprising a plurality of flow parameter sensors for sensing flow parameters at selected positions in the second conduit and furnishing flow parameter information therefrom to the microprocessor. 
     
     
         5 . Apparatus of  claim 2  wherein the microprocessor controls speed of the drive according to an algorithm stored within the microprocessor, the algorithm receiving as input sensed flow parameter information. 
     
     
         6 . Apparatus of  claim 1  further comprising an air flow limiter between an outlet of the second conduit and a suction inlet of the vacuum pump. 
     
     
         7 . Apparatus of  claim 2  further comprising an air flow limiter between an outlet of the second conduit and a suction inlet of the vacuum pump. 
     
     
         8 . Apparatus of  claim 7  further comprising a flow parameter sensor between the air flow limiter and the suction inlet to the pump. 
     
     
         9 . Apparatus of  claim 8  further comprising a second flow parameter sensor upstream of the air flow limiter but downstream of the receiver. 
     
     
         10 . Apparatus of  claim 6  further comprising a solenoid for maintaining the air flow limiter at one of two preselected air flow settings according to whether the solenoid is energized. 
     
     
         11 . Apparatus of  claim 6  wherein the air flow limiter is adjustable between a plurality of positions for differing air flows at each of said positions. 
     
     
         12 . Apparatus of  claim 11  further comprising a solenoid for maintaining the air flow limiter at one of two preselected air flow settings according to whether the solenoid is energized. 
     
     
         13 . Apparatus of  claim 1  wherein the variable speed drive is a variable frequency drive. 
     
     
         14 . Apparatus of  claim 6  wherein the variable speed drive is a variable frequency drive. 
     
     
         15 . Apparatus of  claim 5  wherein the variable speed drive is a variable frequency drive. 
     
     
         16 . Apparatus of  claim 8  wherein the sensor senses static pressure within the second conduit. 
     
     
         17 . Apparatus of  claim 8  wherein the pressure sensor senses dynamic pressure within the second conduit. 
     
     
         18 . Apparatus of  claim 8  wherein the sensor is an anemometer. 
     
     
         19 . Apparatus of  claim 2  wherein the microprocessor communicates with the variable speed drive wirelessly. 
     
     
         20 . Apparatus of  claim 19  wherein the wireless communication is via the Internet. 
     
     
         21 . Apparatus for conveying granular material from a supply to a process machine comprising:
 a. a vessel for receipt and temporary storage of the granular material preparatory to the molding or extrusion;   b. a vacuum pump;   c. a conduit for conveyance of the granular plastic resin material from the supply through the receiver to a vacuum pump;   d. a variable speed drive for the vacuum pump.   
     
     
         22 . Apparatus of  claim 21  further comprising an algorithm stored within the microprocessor, the algorithm receiving as input sensed flow parameter information, the microprocessor controlling speed of the drive according to the algorithm. 
     
     
         23 . Apparatus of  claim 22  further comprising an air flow limiter between the conduit and a suction inlet of the vacuum pump. 
     
     
         24 . Apparatus of  claim 23  wherein the flow parameter sensor is between the air flow limiter and the suction inlet to the pump. 
     
     
         25 . Apparatus of  claim 24  further comprising a second flow parameter sensor upstream of the air flow limiter but downstream of the vessel. 
     
     
         26 . Apparatus of  claim 23  further comprising a solenoid for maintaining the air flow limiter at one of two preselected air flow settings according to whether the solenoid is energized. 
     
     
         27 . Apparatus of  claim 26  wherein the air flow limiter is adjustable between a plurality of positions for differing air flows at each of said positions. 
     
     
         28 . Apparatus of  claim 21  wherein the variable speed drive is an electrically powered variable frequency drive. 
     
     
         29 . Apparatus of  claim 21  wherein the sensor senses static pressure within the conduit. 
     
     
         30 . Apparatus of  claim 21  wherein the sensor senses dynamic pressure within the conduit.