Method and apparatus for controlling the mixing of milled asphalt aggregate with rejuvenating fluid

Abstract

A method and apparatus for controlling the mixing of asphalt aggregate with rejuvenating materials in an asphalt rejuvenating machine. According to the method, milled aggregate is discharged in a windrow of fixed width, and windrow height is compared to rejuvenating machine speed to determine a volume rate of material being processed. A processor controller calculates a required amount of rejuvenating fluid addition based on the volume rate being processed and a desired proportion of rejuvenating fluid to aggregate. The processor controller controls a sprayer which directs rejuvenating fluid at some point along a zone extending from a milling apparatus to a mixer.

I claim:  
     
         1 . A method for controlling the mixing of asphalt aggregate with rejuvenating materials in an asphalt rejuvenating machine, said method comprising the steps of: 
 (i) dislodging a top layer of an asphalt paved surface;    (ii) passing a milling apparatus over the dislodged layer from step (i) to strip said top layer and break up said top layer of said asphalt paved surface to form a milled aggregate;    (iii) adding rejuvenating material to said milled aggregate;    (iv) transferring said milled aggregate to a mixer and blending said milled aggregate with said rejuvenating material to form a blended aggregate.    (v) discharging one of said blended aggregate and said milled aggregate in a windrow of pre-determined width;    (vi) measuring the height of said windrow;    (vii) measuring a speed of travel of said asphalt rejuvenating machine;    (viii) comparing said height with said speed and determining a volume rate of discharge from said mixer;    (ix) determining a desired rate of addition of said rejuvenating materials which corresponds to said volume rate of discharge and a predetermined final composition; and,    (x) adjusting a rate of addition of said rejuvenating material in step (iii) to correspond to said desired rate of addition from step (ix).    
     
     
         2 . A method according to  claim 1  wherein: 
 said adding of said rejuvenating material in step (iii) is carried out at a location along a zone extending from said milling apparatus to said mixer.  
 
     
     
         3 . A method according to  claim 2  wherein said rejuvenating material includes at least a rejuvenating fluid.  
     
     
         4 . A method according to  claim 3  wherein: 
 said height of said windrow is expressed as a first electronic signal;  
 said speed of travel is expressed as a second electronic signal;  
 said first and second electronic signals are sent to a processing controller;  
 said pre-determined final composition is input into said processing controller;  
 said processing controller compares said first and second signals to determine said volume rate of discharge in step (viii);  
 said processing controller compares said volume rate of discharge with said pre-determined final composition to determine said desired rate of addition in step (ix); and,  
 said processing controller at least initiates said adjusting of said rate of addition in step (x).  
 
     
     
         5 . A method as claimed in  claim 4  wherein: 
 said rejuvenating material further includes at least one of sand and aggregate.  
 
     
     
         6 . An asphalt rejuvenating machine comprising: 
 a transport structure movable along an asphalt surface;    a power plant mounted to said transport structure for providing motive force for said transport structure;    a heater mounted to said transport structure for heating said asphalt surface;    a rake mounted to said transport structure to travel behind said heater and scarify said asphalt surface to produce a scarified surface;    a milling apparatus mounted to said transport structure for milling said scarified surface to form a milled aggregate and presenting said milled aggregate to a mixer;    a rejuvenating fluid supply system mounted to said transport structure for supplying rejuvenating fluid to said milled aggregate;    a mixer for blending said milled aggregate with said rejuvenating fluid and depositing a blended aggregate thus formed in a windrow of predetermined width;    a speed sensor for measuring the speed of travel of said transport structure;    a height measuring device for measuring the height of said windrow;    a comparator for comparing said speed of travel with said height to determine a volume rate of discharge of said blended aggregate; and,    a controller associated with said rejuvenating fluid supply system for varying a volume rate at which said rejuvenating fluid is added based on said volume rate of discharge and a pre-determined final composition.    
     
     
         7 . An asphalt rejuvenating machine according to  claim 6  wherein: 
 said rejuvenating fluid supply system includes a rejuvenating fluid tank, a sprayer for spraying said rejuvenating fluid on said milled aggregate, a pump fluidly communicating with said rejuvenating fluid tank and said sprayer for delivering said rejuvenating fluid from said tank to said sprayer, and a flow meter for measuring a volume flow rate of said rejuvenating fluid;  
 said speed sensor is mounted on an axle of said transport structure;  
 said mixer has a discharge opening with a guide for determining said predetermined width of said windrow and a levelling device which rides along a top surface of said windrow;  
 said comparator is part of a central processor unit which receives input from said speed sensor, said height measuring device, an operator control panel and said fluid flow meter; and,  
 said central processor unit acts as said controller by sending an output to a flow regulator which regulates the flow of rejuvenating fluid provided by said pump to said sprayer.  
 
     
     
         8 . An asphalt rejuvenating machine according to  claim 7  wherein said operator control panel receives input from said central processor, displays information as to actual and desired settings relating to a rate of addition of said rejuvenating fluid to said milled aggregate and includes an adjustment control for inputting and varying said rate of addition of rejuvenating fluid to milled aggregate in said blended aggregate.  
     
     
         9 . An asphalt rejuvenating machine according to  claim 8  wherein: 
 said height measuring device is responsive to movement of said levelling device.  
 
     
     
         10 . An asphalt rejuvenating machine according to  claim 9  wherein: 
 said levelling device is a shoe substantially spanning said discharge opening and having a base which inclines upwardly toward a front end thereof;  
 said shoe is attached to said mixer by a parallel bar linkage; and, said mixer is a pug mill.  
 
     
     
         11 . An asphalt rejuvenating machine according to  claim 9  wherein: 
 said levelling device is a flap substantially spanning said discharge opening and pivotably mounted to said mixer for rotation about an axis extending across said discharge opening in a direction transverse to a travel direction of said asphalt rejuvenating machine;  
 said height sensor senses an angular position of said flap; and, said mixer is a pug mill.  
 
     
     
         12 . An asphalt rejuvenating machine according to  claim 9  wherein: 
 said height sensor includes a signal emitter which directs an emitted signal at a top of said windrow and a receiver which receives a reflection of said emitted signal.  
 
     
     
         13 . An asphalt rejuvenating machine according to  claim 12  wherein: 
 said signal emitter emits a light speed signal; and,  
 said central processing unit determines said height of said windrow by measuring a time interval between sending said emitted signal and receiving said reflection of said emitted signal.  
 
     
     
         14 . An asphalt rejuvenating apparatus according to  claim 12  wherein: 
 said signal emitter emits a sound speed signal; and,  
 said central processing unit determines said height of said windrow by measuring a time interval between sending said emitted signal and receiving said reflection of said emitted signal.  
 
     
     
         15 . An asphalt rejuvenating apparatus according to  claim 9  wherein: 
 said speed sensor is coupled to a drive mechanism associated with said power plant for driving at least one wheelset of said transport structure.  
 
     
     
         16 . An asphalt rejuvenating machine comprising: 
 a transport structure movable along an asphalt surface;    a power plant mounted to said transport structure for providing motive force for said transport structure;    a heater mounted to said transport structure for heating said asphalt surface;    a rake mounted to said transport structure to travel behind said heater and scarify said asphalt surface to produce a scarified surface;    a milling apparatus mounted to said transport structure for milling said scarified surface to form a milled aggregate and presenting said milled aggregate to a mixer in a windrow of pre-determined width;    a rejuvenating fluid supply system mounted to said transport structure for supplying rejuvenating fluid to said milled aggregate;    a mixer for blending said milled aggregate with said rejuvenating fluid and discharging said blended aggregate;    a speed sensor for measuring the speed of travel of said transport structure;    a height measuring device for measuring the height of said windrow;    a comparator for comparing said speed of travel with said height to determine a volume rate of discharge of said blended aggregate; and,    a controller associated with said rejuvenating fluid supply system for varying a volume rate at which said rejuvenating fluid is added based on said volume rate of discharge and a pre-determined final composition.    
     
     
         17 . An asphalt rejuvenating machine according to  claim 6  wherein: 
 said rejuvenating fluid supply system includes a rejuvenating fluid tank, a sprayer for spraying said rejuvenating fluid on said milled aggregate, a pump fluidly communicating with said rejuvenating fluid tank and said sprayer for delivering said rejuvenating fluid from said tank to said sprayer, and a flow meter for measuring a volume flow rate of said rejuvenating fluid;  
 said speed sensor is mounted on an axle of said transport structure;  
 said mill has a discharge opening with a guide for determining said predetermined width of said windrow and a levelling device which rides along a top surface of said windrow;  
 said comparator is part of a central processor unit which receives input from said speed sensor, said height measuring device, an operator control panel and said fluid flow meter; and,  
 said central processor unit acts as said controller by sending an output to a flow regulator which regulates the flow of rejuvenating fluid provided by said pump to said sprayer.  
 
     
     
         18 . An asphalt rejuvenating machine according to  claim 17  wherein: 
 said operator control panel receives input from said central processor, displays information as to actual and desired settings relating to a rate of addition of said rejuvenating fluid to said milled aggregate and includes an adjustment control for inputting and varying said rate of addition of rejuvenating fluid to milled aggregate in said blended aggregate.  
 
     
     
         19 . An asphalt rejuvenating machine according to  claim 18  wherein: 
 said height measuring device is responsive to movement of said levelling device.  
 
     
     
         20 . An asphalt rejuvenating machine according to  claim 19  wherein: 
 said levelling device is a shoe substantially spanning said discharge opening and having a base which inclines upwardly toward a front end thereof;  
 said shoe is attached to said mixer by a parallel bar linkage; and, said mixer is a pug mill.  
 
     
     
         21 . An asphalt rejuvenating machine according to  claim 19  wherein: 
 said levelling device is a flap substantially spanning said discharge opening and pivotably mounted to said mixer for rotation about an axis extending across said discharge opening in a direction transverse to a travel direction of said asphalt rejuvenating machine;  
 said height sensor senses an angular position of said flap; and,  
 said mixer is a pug mill.  
 
     
     
         22 . An asphalt rejuvenating machine according to  claim 19  wherein: 
 said height sensor includes a signal emitter which directs an emitted signal at a top of said windrow and a receiver which receives a reflection of said emitted signal.  
 
     
     
         23 . An asphalt rejuvenating machine according to  claim 22  wherein: 
 said signal emitter emits a light speed signal;  
 said central processing unit determines said height of said windrow by measuring a time interval between sending said emitted signal and receiving a reflected signal.  
 
     
     
         24 . An asphalt rejuvenating apparatus according to  claim 22  wherein: 
 said signal emitter emits a sound speed signal; and,  
 said central processing unit determines said height of said windrow by measuring a time interval between sending said emitted signal and receiving a reflected signal.  
 
     
     
         25 . An asphalt rejuvenating apparatus according to  claim 19  wherein: 
 said speed sensor is coupled to a drive mechanism associated with said power plant for driving at least one wheelset of said transport structure.