Abstract:
A control system selectively operates an agitator within a main hopper or bulk tank for a product-on-demand delivery system. A differential pressure switch is used to control operation of the agitator. The differential pressure switch measures the pressure difference between the pressurized air pressure upstream of the tank and tank air pressure to determine when the system is not delivering adequate product to the application units, based on the high air flow rate in the system. When the sensor signals that the system is not delivering adequate product, the system automatically starts the agitator, and conversely when the sensor signals that the system is delivering adequate product, the system automatically stops the agitator.

Description:
FIELD OF THE INVENTION 
   The present invention is directed to an agitation system for an agricultural machine product distribution system. Particularly, the invention relates to a product-on-demand delivery system having a bulk tank for holding product, such as seed, and one or more nozzles for entraining the product in an air stream to feed one or more field application units, wherein the bulk tank includes an agitator therein to facilitate the entrainment of the product in the air stream. 
   BACKGROUND OF THE INVENTION 
   Pneumatic product-on-demand delivery systems have been used on agricultural seeding machines to automatically direct seed from a main seed hopper to a plurality of individual planting units. Each of the individual planting units has an auxiliary seed hopper for receiving the seed, a seed meter for metering the seed from the auxiliary seed hopper and a furrow opener for forming a planting furrow into which the metered seed is deposited. A fan is used to create pressurized air that forms an air stream on which the seed is taken to the planting units. These systems automatically replenish the auxiliary seed hoppers as needed. 
   One such system is described in U.S. Pat. No. 6,609,468, herein incorporated by reference. This product-on-demand delivery system comprises a frame having a main hopper and a plurality of application units. An air pump directs pressurized air to a manifold where the pressurized air is distributed to a plurality of air supply hoses. The air supply hoses are coupled to air inlets located on the bottom of the main hopper. Opposite the air inlets are corresponding product outlets for receiving the air streams and product entrained in the air streams. The product outlets are coupled to product supply hoses that are in turn coupled to auxiliary hoppers located on the application units. The bottom of the main hopper is concave and has outwardly diverging side walls. The air inlet is downwardly angled relative to the bottom and the product outlet is upwardly angled relative to the bottom. 
   Peaked baffles are located above corresponding air inlets and outlets so that product puddles form beneath the baffles. Gaps are formed between adjacent baffles so that product from the main hopper can flow into the product puddles. 
   The nozzle assembly is provided with an agitator assembly having a transverse rod that is provided with a plurality of radially extending fingers. The transverse rod is rotated back and forth by a gearbox/motor assembly. The radially extending fingers sweep the gaps between the individual baffles. 
   Planting systems have to handle many different types of seeds and many different treatments on the seed. Developing a single system that works well with all these different conditions without adjustment is difficult. 
   In the above-described seed-on-demand system, the agitator is configured to begin rotation when the planter is lowered to the ground and is unfolded. This is advantageous in order to ensure that seed is always delivered to the application units, even during the initial filling stage when the planter is not moving. However, the agitator, when used with easy flowing seed, will sometimes continue to push seed into the air stream which can eventually cause the system to plug the product hoses between the main hopper and the application units. 
   The present inventor has recognized that it would be desirable to provide a product-on-demand delivery system that has an increased reliability and a decreased requirement for operator control. The present inventor has recognized that it would be desirable to provide a product-on-demand delivery system that was effective to dispense a variety of seed types and conditions with a minimum of operator control and adjustment. The present inventor has recognized that it would be desirable to provide a product-on-demand delivery system that was effective to dispense a variety of seed types and seed conditions with a minimum of system plugging. 
   SUMMARY OF THE INVENTION 
   The invention provides a control for selectively operating an agitator within a main hopper or bulk tank for a product-on-demand delivery system. According to the preferred embodiment, a differential pressure switch is used to control operation of the agitator. The agitator system operates only under pre-selected conditions. 
   The differential pressure switch on the delivery system measures the difference between the pressurized air pressure into the tank and tank air pressure to electronically “sense” when the system is not delivering adequate product, based on the high air flow rate in the system. When the sensor signals that the system is not delivering adequate product, the system automatically starts the agitator. This situation can occur during initial filling or during planting sticky seeds or when filling at high rates. However, once the meters are full and the corresponding air flow rate is reduced, the differential pressure is reduced and the sensor signals the system to shut off the agitator, preventing the product hoses from being over fed and plugged. 
   According to the preferred embodiments of the invention, a product-on-demand delivery system for dispensing agricultural product onto a field from an agricultural machine includes a frame, a main hopper, at least one application unit, a product hose, an air pump, an agitator, a sensor, and a control system. 
   The main hopper is mounted on the frame. The main hopper has a nozzle assembly or other air entrainment device into which product in the main hopper is directed. The nozzle assembly comprises at least one air inlet and at least one product outlet. The application unit is mounted to the frame. The application unit is provided with a product meter for dispensing the product onto the field. The product hose is flow-coupled to the product outlet and to the product meter. The air pump is pneumatically coupled to the nozzle assembly. The air pump generates pressurized air directed into the nozzle assembly. Product located in the nozzle assembly is taken up by the air stream as the air stream passes through the nozzle assembly to the product outlet. 
   The agitator is located within the main hopper and is actuated to deliver product into the air stream. The sensor is arranged to respond to a magnitude of product flow rate through the product outlet. The control system is signal-connected to the sensor and to the agitator. The control system activates the agitator when the magnitude of product flow rate is determined to be below a pre-selected amount and deactivates the agitator when the magnitude of product flow rate is determined to be above a pre-selected amount. 
   The agitator can be driven by an electrical agitator drive or a mechanical drive controlled by an electric clutch, to mechanically move product within the main hopper. The sensor is pressure-connected to sense a differential pressure between the main hopper and an upstream side of the nozzle assembly downstream of the air pump. The control system comprises an electrical switch, responsive to the differential pressure sensed by the sensor. The control system is then responsive to the state of the switch to start or stop the agitator drive. 
   Alternately, the sensor comprises a differential pressure switch that is pressure-connected to sense a differential pressure between the main hopper and an upstream side of the nozzle assembly downstream of the air pump, and the control system comprises a relay responsive to the state of the switch to start or stop the agitator drive. 
   The differential pressure switch in conjunction with the agitator for the product-on-demand system can make the system more versatile and more automatic. The system also automatically shuts the agitator off when the fan is not running, making it easier to clean the tank. As product-on-demand systems are utilized for wider planters and new crops, a versatile system without the need for operator adjustments is advantageous. 
   Numerous other advantages and features of the present invention will be become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic, side view of an agricultural planter using the subject product-on-demand delivery system. 
       FIG. 2  is a side cross sectional view of the nozzle assembly of the product-on-demand delivery system. 
       FIG. 3  is a side cross sectional view of the nozzle assembly of the product-on-demand delivery system having an air deflecting insert. 
       FIG. 4  is a side cross sectional view of the nozzle assembly of the product-on-demand delivery system having a product exposure limiting element. 
       FIG. 5  is a top perspective view of the air deflecting insert. 
       FIG. 6  is a bottom perspective view of the air deflecting insert. 
       FIG. 7  is a bottom perspective view of the product exposure limiting element. 
       FIG. 8  is a front cross sectional view of the nozzle assembly of the product-on-demand delivery system. 
       FIG. 9  is a front perspective and partial cross sectional view of the nozzle assembly of the product-on-demand delivery system. 
       FIG. 10  is a front perspective view of the nozzle assembly being provided with an agitator assembly. 
       FIG. 11  is a cross sectional view of the nozzle assembly being provided with an agitator assembly. 
       FIG. 12  is a schematic diagram of one control system of the invention. 
       FIG. 13  is a schematic diagram of an alternate control system of the invention. 
   

   DETAILED DESCRIPTION 
   While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
   An agricultural seeding machine  10  comprises a frame  12  on which are mounted a plurality of individual planting units  14 . The planting units  14  are coupled to the frame  12  by a parallelogram linkage  16  so that the individual planting units  14  can move up and down to a limited degree relative to the frame  12 . Each of the individual planting units comprises an auxiliary seed hopper  18  for holding seed, a seed meter  20  for metering seed received from the auxiliary seed hopper  18  and a furrow opener  22  for forming a planting furrow in a field for receiving metered seed from the seed meter  20 . The seed is transferred to the planting furrow from the seed meter by a seed tube  24 . A closing assembly  26  is used to close the planting furrow with the seed contained therein. In the preferred embodiment the seed meter  20  is a vacuum seed meter, although other types of seed meters using mechanical assemblies or positive air pressure could also be used with the subject invention. It should be noted that the present invention could also be used to apply non-seed products to the field. For seed and non-seed products, the planting unit could be considered an application unit with an auxiliary hopper for holding product, a product meter for metering product received from the auxiliary hopper and an applicator for applying the metered product to a field. For example a dry chemical fertilizer or pesticide could be directed to the auxiliary hopper and metered by the product meter and applied to the field by the applicator. 
   The main frame  12  supports a main hopper or tank  30  and an air pump  32 . The air pump  32  is driven by a hydraulic motor; however other motor arrangements could be used, like electric motors for driving the air pump  32 . The air pump  32  directs pressurized air to a manifold  34  through main air hose  36 . The manifold  34  is formed from a hollow closed tubular support of the main frame  12 . The manifold  34  is provided with a plurality of manifold outlets corresponding to the number of planting units  14  mounted to the frame  12 . Individual air supply lines  38  extend from the manifold outlets and direct pressurized air from the manifold  34  to the upstream side of the nozzle assembly  39 . The nozzle assembly  39  is located at the bottom of the main hopper  30 . Product located in the main hopper  30  flows by gravity to the nozzle assembly  39 . The upstream side of the nozzle assembly  39  is provided with a number of air inlets  41  corresponding to the number of air supply hoses  38 . The air inlets  41  are spaced transversely along the upstream side of the nozzle assembly  39 . The downstream side of the nozzle assembly  39  is provided with a number of product outlets  43  corresponding to the number of air supply hoses  38 . The product outlets  43  are also spaced transversely along the downstream side of the nozzle assembly  39 . The product outlets  43  lie opposite from the air inlets  41 . Each air inlet  41  is aligned with a respective product outlet  43 . Product supply hoses  42  extend from the product outlets  43  to the individual auxiliary hoppers  18  for directing product entrained in the air stream to the auxiliary hoppers  18 . 
   The nozzle assembly  39  is provided with a concave bottom  44  having outwardly diverging sidewalls  46 . Product in the form of seed or non-seed product is placed in the main hopper  30  through a lid  48 . Portions of the nozzle assembly  39  can be opened to form a cleanout door  48  as described in U.S. Pat. No. 6,609,468. 
   The air inlet  41  is angled downwardly relative to the concave bottom  44  and correspondingly the product outlet  43  is angled upwardly relative to the concave bottom  44 . An integral baffle  58  extends between the air inlet  41  and the product outlet  43 . The baffle  58  is peaked and is located above the air stream passing from the air inlet  41  to the product outlet  43 . The downwardly angled air inlet  41  prevents product from backing up into the air supply hose  38 , whereas the upwardly angled product outlet  43  prevents product from flowing into and clogging the product supply hose  42 . 
   Adjacent air inlet  41  and product outlet  43  combinations are transversely spaced from one another so that seed or non-seed product can pass on either side of the baffles  58  and puddle beneath the baffles  58 . An air stream passing from the air inlet  41  to the product outlet  43  picks up product located in the puddle and directs it through product supply hose  42  to the auxiliary hopper  18 . The transfer of product from the main hopper  30  to the auxiliary hoppers  18  is done automatically as product is needed by the auxiliary hopper  18 . As an individual auxiliary hopper  18  fills up with product, the auxiliary hopper product inlet  60  becomes covered by product blocking and slowing the air stream so that the air stream no longer picks up product in the main hopper  30  and transports the product to the auxiliary hopper  18 . Conversely, as product is used up by the product meter  20 , the auxiliary hopper product inlet  60  is uncovered and the air stream again picks up product for delivery to the auxiliary hopper  18 . In this way the auxiliary hoppers  18  are always and automatically provided with product. The side walls of the auxiliary hoppers  18  are provided with screen vents  61  for venting air pressure in the auxiliary hoppers  18 . The vent screens  61  can also be located in the lids of the auxiliary hoppers  18  as long as the vent screens  61  are above the respective product inlets. 
   In some situations product having large particles, like large seeds (corn and soybeans), are difficult for the air stream to pick up. To accommodate large seed, the air inlet  41  may be provided with an insert  62  having an air stream deflecting portion  64  that deflects a portion of the air stream downwardly to agitate the seed in the seed puddle and capture the seed in the air stream passing into the product outlet  43 . The insert is provided with a locating tang  66  that engages a slot formed in the air inlet  41  to correctly orient the insert  62  and the air deflecting portion  64 . 
   In other situations the seed or non-seed product may be too light and will be readily carried by even a small air stream. To overcome this problem the baffles  58  may be provided with an element  68 . The element  68  can be clipped on to the baffles  58 . The element has an obstructing bottom  70  that limits the amount of product exposed to the air stream. Element  68  can be made of plastic. The upper gap  74  is opened so that the clip can be clipped to the baffle  58 . 
   According to a preferred embodiment, the large seed insert  62  can be eliminated in favor of an agitator assembly  80 . The agitator assembly  80  comprises a transverse rod  82  extending across the nozzle assembly  39 . The transverse rod  82  is provided with a plurality of radially extending fingers  84 . As shown, in  FIG. 10  the fingers are transversely aligned with one another. 
   The transverse rod  82  is rotated back and forth by an agitator drive  85  comprising a gearbox  86  being driven by a motor  88 . Alternately, the motor  88  can be replaced by an electric clutch that selectively transfers rotary power to the gearbox from a mechanical drive. The mechanical drive can be, for example, a drivetrain that receives rotary power from a wheel of the frame that carries the hopper. 
   At the bottom dead center position of the fingers  84  they extend between the individual nozzles defined by the aligned air inlets  41  and the product outlets  43 . In this way the fingers  84  sweep the area between the nozzles. The gear box/motor assembly  86 / 88  drive the transverse rod fifty-one and one-half degrees in each direction from the bottom dead center illustrated in  FIG. 11 . As such, the fingers  84  sweep an arc of one-hundred three degrees. 
   Hard flowing seed requires more air flow to entrain the seed into the nozzle outlet, and, once the meter elbow at the auxiliary hopper  14  is exposed because adequate seed was not picked up at the tank, a large amount of airflow is present. During this situation, there is a large difference in pressure between the air in the manifold  34  and the tank or hopper  30 . 
   A large pressure drop (approx 2″ H2O) occurs as air flows from the manifold down through the manifold outlet, supply hose, and nozzle inlet. Also, there is a reduced flow restriction for the supply air finds it easier to go out the nozzle outlet and to the now nearly empty auxiliary hopper. 
   Alternately, small seeds that are picked up by low air flows quickly can continually keep the auxiliary hopper full. During planting and especially at end stops, the agitator tends to continually push these small seeds into the air stream under the baffle where they are carried into the nozzle outlet. Over time, the hose can become full as more product is picked up than is metered out at the auxiliary hopper. In this situation, there is very little airflow and hence a very small difference in pressure between component locations in the system. 
   As shown in  FIG. 1  the agitator drive  85  is signal connected to a control  100 . The control  100  is operable to turn on or off the agitator drive  85 , particularly by activating or deactivating the motor  88  ( FIG. 10 ), or alternately, by activating or deactivating an electric clutch (not shown) that communicates rotary power to the agitator system. 
   A differential pressure switch  104  is carried on the frame  12 . The switch  104  is pneumatically connected by a tube  106  to the tank  30  and by a tube  108  to the manifold  34 . The switch  104  is responsive to the differential pressure between the tank  30  and the manifold  34  to change switch states (open to closed, or vice versa) at a pre-selected differential pressure and to electrically indicate the switch state to the control  100  via a signal line  112  that is signal connected to the control  100 . 
   At a high differential pressure the switch  104  has a corresponding switch state that sends a signal through the line  112  to the control  100 . The control  100  turns on the agitator drive  85 . At a low differential pressure the switch  104  has a corresponding switch state that sends a corresponding signal  112  to the control  100  to shut off the agitator drive  85 . 
   Although the pressure taps for the differential pressure switch  104  as are described above are taken at the manifold  34  and the tank  30 , the taps could be between other points that are separated by a distance, or by a pressure drop, along the air path between the air pump  32  and the application units  14 , such that increased or decreased air flow can be sensed. 
   The control  100  can be part of an overall machine controller. 
   As illustrated in  FIG. 12 , the control  100  can be comprised of a relay switch  130  that is charged by a control voltage V 1  through the differential pressure switch  104 . A motor driving voltage V 2  is connected to the switch element  132  of the relay switch  130  as is the positive lead of the agitator motor  88 , or alternately, an electric clutch. When the differential pressure switch  104  changes states, the voltage V 1  causes the relay to switch states to either energize the motor  88 , or alternately, an electric clutch, with the voltage V 2  or de-energize the agitator motor  88 , or alternately, an electric clutch. 
     FIG. 13  illustrates an alternate embodiment wherein a control  140  receives pressure signals from pressure sensors  142 ,  144  from the tank  30  and the manifold  34  respectively, and then, possibly considering other operating parameters from other sensors, starts or stops the agitator drive  85 . In this example the differential pressure sensor incorporates part of the control to compare the signals from the pressure sensors  142 ,  144 . 
   The control  140  can be part of an overall machine controller. 
   From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.