US 4,129,189 A · Weight control system

Abstract

The system controls the weights of individual charges of product or material accumulated by feeding material, preferably at a high "bulk" flow rate and then at a relatively low "dribble" flow rate, into one or more buckets or hoppers. As material is accumulated within each bucket, the system compensates against the effects of vibrational forces and flow rate and, upon termination of material accumulation, it corrects dribble time and final weight by respectively adjusting the bulk and dribble weights for the next charge, all with respect to an electronically established set weight corresponding to the desired weight of each charge. A linear voltage differential transformer (LVDT) senses the position of each bucket and provides electrical signals which are utilized by interface and control circuitry to control charge weight and provide an internal reference. The control system is particularly suited for use in combination with packaging systems.

Claims26

Dependent claims

A weight control system for a bulk-dribble packaging machine wherein individual charges of product are successively accumulated for packaging at a substantially constant bulk flow rate and, upon cessation of bulk flow, at a substantially constant dribble flow rate until a total charge weight approximating a desired set weight is accumulated, which system comprises:

bulk weight adjusting means, responsive to the time taken during dribble flow to accumulate sufficient product to complete a charge, for controlling shut-off of bulk flow to increase or decrease the bulk weight of product accumulated for a subsequent charge at the bulk flow rate when dribble flow time was, respectively, greater or less than a predetermined period for the charge completed;
and dribble weight adjusting means, responsive to the total static charge weight of product accumulated, for controlling shut-off of dribble flow to increase or decrease the dribble weight of product accumulated for a subsequent charge at the dribble flow rate when the total static charge weight of the charge completed was, respectively, less or greater than the desired set weight.

A system for controlling the weights of individual material charges, comprising:

means for establishing a set weight corresponding to the desired weight of successively accumulated charges;
control means for controlling (1) a bulk feeder adapted to feed material at a substantially constant bulk feed rate, and (2) a dribble feeder adapted to feed material at a substantially constant dribble feed rate, the bulk and dribble feeders delivering material to movable receptacle means for temporarily storing each charge, said control means including bulk control means responsive to the position of the receptacle means for first causing the bulk feeder to deposit a bulk weight of material less than said set weight into said receptacle means, and dribble control means responsive to the position of said receptacle means for then causing said dribble feeder to deposit sufficient additional dribble weight of material into said receptacle means that the combined bulk and dribble weights equal said set weight, said bulk control means including dribble correction means for adjusting the bulk weight to be accumulated subsequently in said receptacle means in relation to the time period required to accumulate said dribble weight, said dribble control means including final weight correction means for adjusting the dribble weight to be accumulated subsequently in said receptacle means in relation to the combined bulk and dribble weights;
and
interface means operatively associated with said control means and said receptacle means for providing a direct current electrical signal proportional to the position of said receptacle means to indicate the weight of material therein, means for filtering said signal to produce a filtered weight signal, and means for differentiating said filtered weight signal to produce a rate signal.

1 more element

A system for controlling the weights of individual material charges, comprising:

p1 means for establishing a set weight corresponding to the desired weight of successively accumulated charges;
control means for controlling (1) a bulk feeder adapted to feed material at a substantially constant bulk feed rate, and (2) a dribble feeder adapted to feed material at a substantially constant dribble feed rate, the bulk and dribble feeders delivering material to movable receptacle means for temporarily storing each charge, said control means including bulk control means responsive to the position of the receptacle means for first causing the bulk feeder to deposit a bulk weight of material less than said set weight into said receptacle means, and dribble control means responsive to the position of said receptacle means for then causing said dribble feeder to deposit sufficient additional dribble weight of material into said receptacle means that the combined bulk and dribble weights equal said set weight, said bulk control means including dribble correction means for adjusting the bulk weight to be accumulated subsequently in said receptacle means in relation to the time period required to accumlate said dribble weight, said dribble control means including final weight correction means for adjusting the dribble weight to be accumulated subsequently in said receptacle means in relation to the combined bulk and dribble weights;
sensing means operatively associated with said receptacle means for sensing the position of said receptacle means and simultaneaously providing two alternating current signals 180.degree. out of phase;
and
interface means operatively interconnecting said sensing means and said bulk and dribble control means, said interface means including means for adding said signals to produce a weight signal, and means for subtracting said signals to produce a reference signal.

2 more elements

A system for controlling the weights of individual material charges, comprising:

means for establishing a set weight corresponding to the desired weight of successively accumulated charges;
control means for controlling (1) a bulk feeder adapted to feed material at a substantially constant bulk feed rate, and (2) a dribble feeder adapted to feed material at a substantially constant dribble feed rate, the bulk and dribble feeders respectively delivering material to movable bulk and dribble receptacle means for temporarily storing each charge, said control means including bulk control means responsive to the position of the receptacle means for first causing the bulk feeder to deposit a bulk weight of material less than said set weight into said receptacle means, and dribble control means responsive to the position of said receptacle means for then causing said dribble feeder to deposit sufficient additional dribble weight of material into said receptacle means that the combined bulk and dribble weights equal said set weight, said bulk control means including dribble correction means for adjusting the bulk weight to be accumulated subsequently in said receptacle means in relation to the time period required to accumulate said dribble weight, said dribble control means including final weight correction means for adjusting the dribble weight to be accumulated subsequently in said receptacle means in relation to the combined bulk and dribble weights;
two linear variable differential transformers respectively operatively connected with said bulk and dribble receptacle means, each transformer providing two alternating current signals 180.degree. out of phase;
and
two interface means respectively operatively interconnecting said transformers and said bulk and dribble control means, each interface means including means for adding the respective signals to produce a weight signal, and means for subtracting the respective signals to produce a reference signal, and wherein said bulk and dribble control means each include means for combining said weight and reference signals and producing a signal proportional to the position of the respective receptacle means.

2 more elements

Dependencies are inferred from the claim text.

Weight control system

Life of this patent

Weight control system

Life of this patent

Abstract

Claims26