Priority interrupt circuit

Control circuitry of controlling the feeding of material from at least a single source to a plurality of stations to prevent overfeed of any one or more of said stations during the purging of at least a single pneumatic line connecting said source and stations, each station having operable means for extracting said material from said line and means for indicating demand or no demand for said material, comprising:

• means for causing said source to supply said material to said line when at least one of said indicating means indicates a demand for said material,
• first operating means for effectively checking said indicating means and operating the said extracting means associated with an indicating means indicating a demand for said material, and
• overfill prevention purging means including relay means which is connected to a current supply after operation of said first operating means so as to be activated and to cause at least one of only the said extracting means operated by said first operating means during the last predetermined number of operations thereof to purge said line and thus effectively prevent overfeed of any station whose associated extracting means was not operated by said first operating means during the said last predetermined number of operations thereof, and including capacitor means connected in parallel with said relay means for maintaining said relay means activated for a short time after said relay means is disconnected from said supply means.

Control circuitry of controlling the feeding of material from at least a single source to a plurality of stations to prevent overfeed of any one or more of said stations during the purging of at least a single pneumatic line connecting said source and stations, each station having operable means for extracting said material from said line and means for indicating a demand or no demand for said material, comprising:

• means for causing said source to supply said material to said line when at least one of said indicating means indicates a demand for said material,
• first operating means for effectively checking said indicating means and operating the said extracting means associated with an indicating means indicating a demand for said material, and
• overfill prevention purging means including relay means which is connected to a current supply after operation of said first operating means so as to be activated and to cause at least one of only the said extracting means operated by said first operating means during the last predetermined number of operations thereof to purge said line and thus effectively prevent overfeed of any station whose associated extracting means was not operated by said first operating means during the said last predetermined number of operations thereof, and including switch means connected to said relay means for maintaining said relay means associated with the last station supplied in a cycle activated after said relay means is disconnected from said supply means.

A control apparatus for a material distribution system having pneumatic means for conveying fiber material, entrained in an air stream and supplied to that air stream from at least one source, to a plurality of stations having a set priority for receiving said fiber material, switch means at each station for indicating a demand for said fiber material having a first position indicating demand and a second position not indicating demand, and means at each station and associated with said indicating means for removing said fiber material from said air stream with said entrained fiber material when a source of electrical energy is applied to said removing means comprising:

• means for causing said material source to supply said fiber material to said air stream whenever one of said indicating means indicates a demand for said fiber material,
• a source of electrical energy,
• relay means associated with each said station having coil means actuated by connection to said energy source when said switch means of that station is in said first position and the switch means of all other stations having a higher priority are a said second position,
• switch means associated with each said coil means and controlled by said coil means for connecting said removing means to said energy source when said coil means is activated,
• capacitive means associated with each said coil means and connecting in parallel with said coil means for retaining said coil means activated after said coil means is disconnected from said energy source,
• means for purging said pneumatic means, after all of said stations demanding fiber material have been satisfied, through all the stations having said coil means retained activated after all of said stations demanding fiber material have been satisfied, and
• means for preventing said causing means from causing said fiber material source to apply fiber material to said air stream during purging.

A method of feeding material from at least a single source to a plurality of stations having a set priority for receiving said material so as to prevent overfill of any said station during purging of at least a single pneumatic line connecting said source and stations, each station having means for extracting said material and means for indicating demand and no demand for said material comprising the steps of:

• supplying material to said line whenever at least one of said indicating means indicates a demand for said material,
• operating one at a time in an order determined by said set priority said extracting means of each of said stations having an indicating means indicating a demand for said material when checked and when all stations of said plurality of stations having a higher priority are not indicating a demand for fibers so that a cycle is completed after all of said indicating means indicate no demand for said material,
• interrupting the feeding of a station whenever a station having a higher priority indicates a demand and operating the said extracting of said station having a higher priority, and
• operating after the completion of each cycle, one of only the said extracting means operated within a given number of past cycles so as to purge said line.