Demand throttle methods and apparatuses

Abstract

An apparatus for wrapping a load with packaging material may include a packaging material dispenser for dispensing packaging material. The apparatus may also include a relative rotation assembly for providing relative rotation between the load and the packaging material dispenser. The apparatus may further include a mechanical connection operatively coupling the packaging material dispenser to the relative rotation assembly. The relative rotation assembly may be configured to drive the packaging material dispenser through the mechanical connection. The apparatus may further include a force exerting mechanism operatively coupled to the mechanical connection. The apparatus may further include a sensing element configured sense a characteristic of dispensed packaging material. The sensing element may be operatively coupled to the mechanical connection. The force exerting mechanism and the sensing element may be configured to control the mechanical connection to maintain a selected ratio of packaging material dispensed to demand for packaging material at the load for at least a portion of a wrap cycle.

1 . An apparatus for wrapping a load with packaging material, comprising:
 a packaging material dispenser for dispensing packaging material;   a relative rotation assembly for providing relative rotation between the load and the packaging material dispenser;   a mechanical connection operatively coupling the packaging material dispenser to the relative rotation assembly, wherein the relative rotation assembly is configured to drive the packaging material dispenser through the mechanical connection;   a force exerting mechanism operatively coupled to the mechanical connection; and   a sensing element configured sense a characteristic of dispensed packaging material, the sensing element being operatively coupled to the mechanical connection;   wherein the force exerting mechanism and the sensing element are configured to control the mechanical connection to maintain a selected ratio of packaging material dispensed to demand for packaging material at the load for at least a portion of a wrap cycle.   
     
     
         2 . The apparatus of  claim 1 , wherein the force exerting mechanism and the sensing element are configured to maintain the ratio of packaging material dispensed to demand at a level sufficient to produce a desired wrap force on the load. 
     
     
         3 . The apparatus of  claim 1 , wherein the force exerting mechanism and the sensing element are configured to maintain the ratio of packaging material dispensed to demand at a level sufficient to produce a desired containment force on the load. 
     
     
         4 . The apparatus of  claim 1 , wherein the force exerting mechanism and the sensing element are configured to maintain the ratio of packaging material dispensed to demand at a level sufficient to meet the containment needs of the load. 
     
     
         5 . The apparatus of  claim 1 , wherein the force exerting mechanism and the sensing element are configured to maintain the ratio of packaging material dispensed to demand within a range of values sufficient to maintain at least one of a wrap force and a containment force exerted on the load in a range sufficient to meet containment needs of the load. 
     
     
         6 . The apparatus of  claim 1 , wherein the force exerting mechanism includes a spring member configured to exert a force on the mechanical connection. 
     
     
         7 . The apparatus of  claim 6 , wherein the force exerting mechanism includes a compression spring. 
     
     
         8 . The apparatus of  claim 6 , wherein the sensing element is configured to exert a force on the mechanical connection based at least in part on the sensed characteristic. 
     
     
         9 . The apparatus of  claim 8 , wherein the force exerted by the force exerting mechanism and the force exerted by the sensing element oppose one another. 
     
     
         10 . The apparatus of  claim 9 , wherein the mechanical connection includes an input and an output. 
     
     
         11 . The apparatus of  claim 10 , wherein the mechanical connection is configured such that connectivity between the input and the output increases when the force exerted by the sensing element overcomes the force exerted by the force exerting mechanism. 
     
     
         12 . The apparatus of  claim 10 , wherein the mechanical connection is configured such that connectivity between the input and the output decreases when the force exerted by the force exerting mechanism overcomes the force exerted by the sensing element. 
     
     
         13 . An apparatus for wrapping a load with packaging material, comprising:
 a packaging material dispenser for dispensing packaging material;   a relative rotation assembly for providing relative rotation between the load and the packaging material dispenser;   a mechanical connection operatively coupling the packaging material dispenser to the relative rotation assembly, wherein the relative rotation assembly is configured to drive the packaging material dispenser through the mechanical connection; and   a sensing element configured to sense a change in demand for packaging material at the load and adjust the mechanical connection in response to the change in demand to maintain a ratio of packaging material dispensed to demand in a selected range for at least a portion of a wrap cycle.   
     
     
         14 . The apparatus of  claim 13 , wherein the sensing element is configured to engage a portion of the packaging material extending between the packaging material dispenser and the load to sense the change in demand. 
     
     
         15 . The apparatus of  claim 13 , wherein the demand is an instantaneous demand. 
     
     
         16 . The apparatus of  claim 13 , wherein the sensing element is configured to respond to the change in packaging material demand by moving from a first position to a second position. 
     
     
         17 . The apparatus of  claim 16 , wherein the sensing element includes a shaft including a hinged fixed end and a free end, the shaft being configured to swing about the hinged fixed end between the first position and the second position. 
     
     
         18 . The apparatus of  claim 17 , further including a force exerting mechanism coupled to the shaft, the force exerting mechanism being configured to exert a force on the shaft. 
     
     
         19 . The apparatus of  claim 18 , wherein the force exerting mechanism is configured to maintain the ratio of packaging material dispensed to demand substantially constant as demand changes by controlling positioning of the sensing element with the force exerted by the force exerting mechanism. 
     
     
         20 . The apparatus of  claim 18 , wherein a first portion of the force exerting mechanism is coupled to the shaft. 
     
     
         21 . The apparatus of  claim 20 , wherein a second portion of the force exerting mechanism is coupled to a frame portion of the packaging material dispenser. 
     
     
         22 . The apparatus of  claim 17 , further including a force exerting mechanism coupled to the mechanical connection, the force exerting mechanism being configured to exert a force on the mechanical connection. 
     
     
         23 . The apparatus of  claim 22 , wherein the force exerting mechanism includes an arm slidably received in a housing. 
     
     
         24 . The apparatus of  claim 23 , wherein the force exerting mechanism includes a spring engaging the arm and the housing, the spring being configured to bias the arm to an extended position relative to the housing. 
     
     
         25 . The apparatus of  claim 23 , wherein the arm is coupled to the mechanical connection, and the housing is coupled to a frame portion of the packaging material dispenser. 
     
     
         26 . The apparatus of  claim 25 , wherein the arm is selectively fastened along a slot in the mechanical connection. 
     
     
         27 . The apparatus of  claim 26 , wherein moving the arm along the slot in a first direction increases the force exerted on the mechanical connection by the force exerting mechanism. 
     
     
         28 . The apparatus of  claim 27 , wherein moving the arm along the slot in a second direction decreases the force exerted on the mechanical connection by the force exerting mechanism. 
     
     
         29 . The apparatus of  claim 13 , wherein the mechanical connection includes a mechanical input/output ratio control operatively coupling the relative rotation assembly to the packaging material dispenser. 
     
     
         30 . The apparatus of  claim 29 , wherein the mechanical input/output ratio control includes a hydrostatic transmission. 
     
     
         31 . The apparatus of  claim 29 , wherein an input of the mechanical input/output ratio control is operatively coupled to the relative rotation assembly. 
     
     
         32 . The apparatus of  claim 31 , wherein an output of the mechanical input/output ratio control is operatively coupled to the packaging material dispenser. 
     
     
         33 . The apparatus of  claim 32 , wherein connectivity between the input and the output of the mechanical input/output ratio control is determined at least in part by positioning of the sensing element. 
     
     
         34 . The apparatus of  claim 33 , wherein movement of the sensing element in a first direction increases connectivity between the input and output of the mechanical input/output ratio. 
     
     
         35 . The apparatus of  claim 34 , wherein movement of the sensing element in a second direction decreases connectivity between the input and output of the mechanical input/output ratio. 
     
     
         36 . The apparatus of  claim 34 , wherein movement of the sensing element in a second direction is indicative of a decrease in connectivity between the input and output of the mechanical input/output ratio. 
     
     
         37 . A method for wrapping a load with packaging material, the method comprising:
 providing relative rotation between a packaging material dispenser and the load with a relative rotation assembly;   driving the packaging material dispenser to dispense packaging material with the relative rotation assembly through a mechanical connection operatively coupling the packaging material dispenser and the relative rotation assembly;   engaging a portion of the packaging material extending between the packaging material dispenser and the load with a sensing element, wherein a change of position of the sensing element is indicative of a change in demand for packaging material at the load; and   adjusting the mechanical connection based at least in part on movement of the sensing element to maintain a ratio of packaging material dispensed to demand in a selected range for at least a portion of a wrap cycle.   
     
     
         38 . The method of  claim 37 , wherein movement of the sensing element is indicative of a change in load girth between a first portion of the load and a second portion of the load. 
     
     
         39 . The method of  claim 37 , wherein movement of the sensing element is indicative of a change in the shape of a portion of the load being wrapped. 
     
     
         40 . The method of  claim 37 , wherein driving the packaging material dispenser to dispense packaging material with the relative rotation assembly through a mechanical connection includes driving the packaging material dispenser to dispense packaging material with the relative rotation assembly through a mechanical input/output ratio control. 
     
     
         41 . The method of  claim 40 , wherein adjusting the mechanical connection operatively coupling the packaging material dispenser and the relative rotation assembly includes adjusting power transmission in the mechanical input/output ratio control. 
     
     
         42 . The method of  claim 40 , wherein adjusting power transmission in the mechanical input/output ratio control includes adjusting connectivity between an input of the mechanical input/output ratio control and an output of the mechanical input/output ratio control. 
     
     
         43 . The method of  claim 37 , further including controlling movement of the sensing element with an adjustable force exerting mechanism to maintain the ratio of packaging material dispensed to demand. 
     
     
         44 . A method for wrapping a load with packaging material, the method comprising:
 providing relative rotation between a packaging material dispenser and the load with a relative rotation assembly;   driving the packaging material dispenser to dispense packaging material with the relative rotation assembly through a mechanical connection operatively coupling the packaging material dispenser and the relative rotation assembly; and   controlling the mechanical connection with a sensing element operatively coupled to the mechanical connection;   engaging a portion of the packaging material extending between the packaging material dispenser and the load with the sensing element to monitor tension of the packaging material; and   moving the sensing element to control the mechanical connection to maintain an amount of packaging material dispensed relative to the demand for packaging material at the load in a selected range for at least a portion of a wrapping cycle.   
     
     
         45 . The method of  claim 44 , wherein maintaining an amount of packaging material dispensed relative to the demand for packaging material at the load substantially constant includes maintaining the amount dispensed relative to the demand substantially constant as tension of the packaging material varies. 
     
     
         46 . The method of  claim 44 , wherein tension in the packaging material changes due to a change in load girth. 
     
     
         47 . The method of  claim 44 , wherein tension in the packaging material changes due to a change in a shape of the load. 
     
     
         48 . The method of  claim 44 , wherein driving the packaging material dispenser to dispense packaging material with the relative rotation assembly through a mechanical connection includes driving the packaging material dispenser with the relative rotation assembly through a mechanical input/output ratio control. 
     
     
         49 . The method of  claim 48 , wherein moving the sensing element includes pivoting the sensing element about a hinged fixed end. 
     
     
         50 . The method of  claim 49 , wherein pivoting the sensing element adjusts the mechanical input/output ratio control. 
     
     
         51 . The method of  claim 44 , further including controlling movement of the sensing element with an adjustable force exerting mechanism. 
     
     
         52 . The method of  claim 44 , wherein maintaining an amount of packaging material dispensed relative to demand in a selected range includes maintaining the amount of packaging material dispensed relative to the demand substantially constant for at least a portion of the wrapping cycle. 
     
     
         53 . A method for wrapping a load with packaging material, the method comprising:
 providing relative rotation between a packaging material dispenser and the load with a relative rotation assembly;   driving the packaging material dispenser to dispense packaging material with the relative rotation assembly through a mechanical connection operatively coupling the packaging material dispenser and the relative rotation assembly;   engaging a portion of the packaging material extending between the dispensing assembly and the load with a sensing element operatively coupled to a control element of the mechanical connection;   exerting a force on the control element with an adjustable force exerting mechanism; and   controlling the mechanical connection with the control element, through positioning of the sensing element and force exerted by the adjustable force exerting mechanism, to maintain a ratio of packaging material dispensed relative to demand for packaging material at the load substantially constant for at least a portion of a wrap cycle.   
     
     
         54 . The method of  claim 53 , wherein exerting a force on the control element includes exerting the force on the control element with a spring device. 
     
     
         55 . The method of  claim 54 , wherein exerting the force on the control element with a spring device includes adjusting the force exerted on the control element by adjusting the spring device. 
     
     
         56 . The method of  claim 55 , wherein adjusting the spring device includes adjusting a length of the spring device. 
     
     
         57 . The method of  claim 53 , wherein driving the packaging material dispenser with the relative rotation assembly through a mechanical connection includes driving the packaging material dispenser with the relative rotation assembly through a mechanical input/output ratio control operatively coupling the relative rotation assembly to the packaging material dispenser. 
     
     
         58 . The method of  claim 57 , wherein controlling the mechanical connection with the control element includes adjusting connectivity between the input and output of the mechanical input/output ratio control. 
     
     
         59 . The method of  claim 57 , wherein driving the packaging material dispenser with the relative rotation assembly through a mechanical input/output ratio control includes driving the packaging material dispenser with the relative rotation assembly through a hydrostatic transmission. 
     
     
         60 . The method of  claim 59 , wherein controlling the mechanical connection with the control element includes adjusting a valve assembly in the hydrostatic transmission. 
     
     
         61 . An apparatus for stretch wrapping a load, comprising:
 a packaging material dispenser for dispensing packaging material, the packaging material dispenser including a dispensing assembly for pre-stretching the packaging material;   a relative rotation assembly for providing relative rotation between the load and the packaging material dispenser;   a mechanical connection operatively coupling the dispensing assembly to the relative rotation assembly, wherein the relative rotation assembly is configured to drive the dispensing assembly through the mechanical connection;   a sensing roller configured to sense a change in demand for packaging material at the load, and to move to adjust the mechanical connection in response to the change in packaging material demand; and   an adjustable force exerting mechanism operatively coupled to the sensing roller, the adjustable force exerting mechanism being configured to control movement of the sensing roller.   
     
     
         62 . An apparatus for wrapping a load with packaging material, comprising:
 a packaging material dispenser for dispensing packaging material;   a relative rotation assembly for providing relative rotation between the load and the packaging material dispenser;   a mechanical connection operatively coupling the packaging material dispenser to the relative rotation assembly, wherein the relative rotation assembly is configured to drive the packaging material dispenser through the mechanical connection;   a force exerting mechanism operatively coupled to the mechanical connection; and   a sensing element configured sense a characteristic of dispensed packaging material, the sensing element being operatively coupled to the mechanical connection;   wherein the force exerting mechanism and the sensing element are configured to control the mechanical connection to maintain a wrap force exerted by the dispensed packaging material on the load in a selected force range for at least a portion of a wrap cycle.   
     
     
         63 . The apparatus of  claim 62 , wherein the force exerting mechanism and the sensing element are configured to maintain the wrap force in the selected force range by maintaining a ratio of packaging material dispensed to demand for packaging material at the load in a selected ratio range.