Delivery control system for vehicle-mounted spreader

#The present invention relates to material handling and more particularly to a delivery control system for a vehicle-mounted spreader.

#In color climates it is a common practice to spread sand, salt/sand mixtures or heat-producing bulk chemicals onto icy or snowpacked streets and highways. Spreading trucks used for this task generally include a bulk material storage hopper, a belt or screw type conveyor for delivering the bulk material to be spread from the storage hopper to the rear of the truck and a spinner for spreading the delivered material over a path of predetermined width. The amount of bulk material spread is, generally speaking, a function of the conveyor speed. The spinner speed, which typically remains constant, controls only the width of the covered path.

#Ideally, the bulk material is to be spread at a uniform rate since too much material is wasteful while too little material does not substantially improve roadway conditions. The latter situation is particularly dangerous since a driver who has been lulled into complacency by sections of properly treated roadway may not be alert enough to avoid an accident when an inadequately treated section of roadway is unexpectedly encountered.

#While the specification concludes with claims particularly pointing out and distinctly claiming that which is regarded as the present invention, details of a preferred embodiment of the invention may be more readily ascertained from the following detailed description when read in conjunction with the accompanying drawings wherein:

#FIG. 1 is a schematic diagram of a delivery control system constructed in accordance with the present invention; and

#FIG. 2 is a schematic diagram including details of the controller 24 in FIG. 1.

#Referring to FIG. 1, a delivery control system constructed in accordance with the present invention can control the linear speed of a belt-type conveyor 10 which receives bulk material 12 gravity fed from a conventional truck-mounted storage hopper 14. The conveyor is driven by a direct current drive motor 16 coupled to a conveyor drive roller 18 through a speed-reducing gear system 20.

#A belt-driven generator 22 on the truck engine provides a controlled voltage for the drive motor 16 to enable that motor to drive the conveyor at a speed proportional to the road speed of the truck. In a preferred embodiment of the invention, the field voltage of motor 16 is fixed while the armature voltage is varied to control the motor speed. Generator 22 is preferably a conventional direct current shunt generator manufactured for heavy duty automotive use. Heavy duty truck engines normally include a mounting bracket for an auxiliary generator, such as generator 22.

#The magnitude of the direct current voltage produced by generator 22 is a function of its field current. The magnitude of the field current is, in turn, regulated by controller 24 having a negative feedback 26 from the armature of generator 22 and an input from a reference voltage means 28 which preferably comprises a manually-adjustable potentiometer which an operator can use to establish a voltage representing a desired material delivery rate in terms of bulk material weight per unit of distance. In the English system of measure, the potentiometer would probably be calibrated in pounds of material per mile of roadway.