Abstract:
A differential pressure sensor measures the vacuum in a material conveying duct relative to atmospheric pressure or to a positive pressure farther upstream in the duct on an agricultural harvester. The output from this sensor is monitored electronically, and the resulting output is used to optimize harvester speed. In one embodiment, a processor monitor output is used in conjunction with the pressure sensor output to control ground speed. Processor speed or loading and air duct pressure are monitored to determine which area of the machine is the limiting factor and to adjust the harvester speed accordingly.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to an agricultural harvester having an air duct system to convey harvested material and, more specifically, to a device for controlling harvester speed dependent on the pressure in the duct system.  
       BACKGROUND OF THE INVENTION  
       [0002]     The harvesting capacity of a cotton harvester is determined by the capacity of the harvesting unit to remove the cotton from the plant and the capacity of the air system to convey the cotton downstream from the harvesting unit. If the harvester is a cotton stripper equipped with a cotton cleaner, the capacity of the cleaner to process and remove the burs and foreign material from the cotton also affects the overall machine capacity.  
         [0003]     The operator can see when the row units are operating at or above capacity by the amount of cotton left on the stalk, and in over-speed conditions, excess cotton will remain. However, a monitor system is required for the operator to determine if the air system and cleaner are running close to capacity. Current cotton strippers have a speed sensor on the top saw of the cleaner. A readout in the cab provides top saw speed which gives the operator an indication of percent of full capacity of the cleaner. If the top saw slows below a predetermined lower speed, an audible alarm and light will be activated to warn the operator that the machine must be slowed to avoid cleaner plugging. Conversely, the readout informs the operator there is additional capacity in the cleaner so machine speed can be increased to gain productivity.  
         [0004]     Many cotton material conveying systems include a nozzle pointed downstream in the air duct to induce a vacuum in the lower part of the duct which draws removed material upwardly. Manually adjustable vacuum switches using a spring and diaphgram are available to measure the difference in pressure between the lower portion of the air duct and the cab. When the vacuum falls below the set point as a result duct capacity being approached or exceeded, the sensor triggers a light and audible alarm to warn the operator to decrease harvester speed. Several problems exist with present vacuum monitoring systems. First, the systems measure the vacuum relative to cab pressure, and cab pressure can vary if the cab air conditioning system blower speed is changed, the cab door is opened, or the cab inlet filter gets plugged. Any such variance requires the operator to reset the sensor for effective operation. Secondly, setting the sensor requires a trial and error approach wherein the operator increases speed until the machine plugs to see if the sensor is set correctly. If the setting is incorrect, the operator must readjust the setting to try to initiate a warning just before the duct blockage condition occurs. The third problem with the current vacuum system is inability of such a system to inform the operator when there is additional capacity available in the air system. As a result, machine productivity is compromised.  
       SUMMARY OF THE INVENTION  
       [0005]     It is therefore an object of the present invention to provide an improved system for monitoring a harvester air duct system. It is a further object to provide such a system which overcomes most or all of the aforementioned problems.  
         [0006]     It is another object of the present invention to provide an improved system for monitoring a harvester air duct system which is reliable, easy to calibrate and unaffected by changes in air pressure in the cab of the harvester. It is yet a further object to provide such a system which helps the harvester operator maintain peak machine productivity and reduces incidences of the machine overload or under-capacity operation.  
         [0007]     It is still another object of the invention to provide an improved air duct monitoring system for a cotton harvester. It is another object to provide such a system which can be utilized to maintain optimum harvester operating speed and which can be combined with a monitor for another area, such as a cleaner, to determine which area is the capacity limiting factor on the harvester and select that area monitor to control operating speed.  
         [0008]     One system constructed in accordance with the teachings of the present invention utilizes a temperature compensated differential pressure sensor to measure the vacuum in the duct relative to atmospheric pressure or to a positive pressure farther upstream in the duct. The output from this sensor is monitored electronically and can be displayed and/or used to optimize vehicle speed. In addition, a machine processor monitor output can be used in conjunction with the pressure sensor to control ground speed. Cleaner speed and vacuum in the air duct are monitored to determine which area of the machine is the limiting factor and to adjust harvester speed dependent on that limiting factor.  
         [0009]     The system is not affected by the variation in cab pressure. Therefore, need for resetting is reduced or eliminated, or achieved automatically. Additionally, the system continuously identifies duct vacuum, which will allow the operator or an automatic speed control system to adjust vehicle ground speed to optimize performance. Loading on a crop processor structure is also monitored to provide a load indication which is used to control harvester ground speed. The system allows an inexperienced person to operate the machine near maximum capacity without plugging and relieves operator stress by automatically controlling the ground speed. The operator does not have to watch the cleaner speed and vacuum as closely and has more time to monitor and control other machine functions.  
         [0010]     These and other objects, features and advantages of the present invention will become apparent upon reading the following detailed description in view of the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a side view of a portion of a harvester having an air duct system and a crop processing unit. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]     Referring now to  FIG. 1 , therein is shown a cotton harvester  10  having a main frame  12  supported for forward movement over the ground by forward drive wheels  16  and rear steerable wheels (not shown). A cab  18  is supported on the forward end of the frame  12 . A lift frame is adjustably supported from the forward end of the frame  12  for mounting a conventional header  22  for stripping cotton material from rows of cotton plants. The header  22  includes a cross auger  26  for conveying stripped cotton and other material to a central outlet location which opens rearwardly into a separation duct  28 .  
         [0013]     Air duct structure  30  with an S-shaped configuration curves upwardly and rearwardly from the separation duct  28  to an upper separation grate area structure  34  which selectively directs conveyed material downwardly through an input duct  36  to an on-board processor such as a cotton cleaner  38  as shown in  FIG. 1 , or rearwardly to a basket or receptacle through an outlet area  40 . The grate area  34  is supported from the frame via duct  36  and cleaner  38  and provides principle support for the duct structure  30 . An air system including an air jet nozzle structure  42  in the rear of the duct structure  30  directs air upwardly and induces air flow upwardly from the duct  28  to direct cotton and other light material rearwardly and upwardly towards the grate area structure  34 . Heavy materials such as green bolls drop from the stream of conveyed material through openings near the bottom of the separation duct  28  and below the grate area structure  34 , while light trash exits through the grate area  34 . For further details of the duct structure  30  and separation grate area structure  34 , reference may be had to U.S. Pat. Nos. 4,606,177 and 6,321,516.  
         [0014]     The onboard processor  38  includes several drives  50 ,  52  and  54  with drive shaft monitors  60 ,  62  and  64 . As shown, the drives  50 ,  52  and  54  provide power to feeder, primary saw, and reclaimer saw drums, and drive to an auger and cleaner fan. The shaft monitors  60 ,  62  and  64  provide a signal to an electronic controller  70  on the harvester indicative of loading on the drives. For example, shaft speeds can be monitored, and if the processor  38  is overloaded with an excess amount of harvested material, the shaft speed on one or more of the drives  50 ,  52  and  54  will slow below a preselected acceptable speed range. During field operations, the controller  70  polls the shaft monitors  60 ,  62  and  64  and provides an indication of processor loading and of pending or actual shaft overload conditions so the operator can slow the machine to bring loads at the processor into the desired operating ranges. In addition to detecting and warning of potential overload conditions, the processor also provides an indication of the percentage of processor utilization so that the harvester speed can be controlled to better utilize machine capacity and increase productivity.  
         [0015]     A pressure monitor system indicated generally at  80  is provided at the duct structure  30  and is connected to the electronic controller  70 . The monitor system  80  includes at least one duct pressure monitor  82  for providing pressure signals indicative of the pressure in the duct at one or more locations  83  in the duct. The pressure at the location  83  relative to atmospheric pressure outside the cab  18  is determined. The pressure monitor  82  includes a pressure input connected by tubes  84  to vacuum sensor ports at location  83  on each side of the lower portion of the duct structure  30 . The monitor  82  is attached to the harvester at a protected location. As shown in  FIG. 1 , the port locations  83  are below the jet nozzle structure  42  in a duct area having a negative pressure relative to atmosphere during normal harvesting operations. If the duct structure  30  approaches a maximum capacity condition or a blockage begins to form, the vacuum level below the jet nozzle structure will decrease below a preselected minimum value. In one embodiment of the invention, the electronic controller  70  provides an indication of the problem so the operator can slow or stop the harvester to alleviate the duct overload or potential overload condition before a blockage occurs. The controller  70  can include a readout device, an audio or visual warning device, or a combination of devices for indicating under- and over-capacity conditions and percentage of maximum capacity usage. The pressure monitor system  80  is temperature compensated for accuracy over a wide range of operating conditions. For example, the monitor  82  can include temperature compensation to reduce or eliminate calibration requirements.  
         [0016]     Additional pressure monitors such as shown at  86  and  88  may be added to monitor pressure at different locations in the air system on the harvester to facilitate early warning of potential problems such as overloads or blockages of the duct and provide additional diagnostic information to the operator. Pressures at the different areas are monitored by the controller  70  and compared to each other or to atmospheric pressure outside the cab  18 . If a pressure reading at one of the monitors is outside of an acceptable range relative to either atmosphere or to another monitor reading, a warning is provided. The multiple pressure monitors also facilitate optimization of maximum duct structure utilization. A single pressure monitor such as the lower vacuum monitor  82  can be utilized to provide pressure signals to the controller  70  for calculating an estimated duct structure percentage of capacity utilization or other suitable capacity-related indication to display to the operator for use with the processor utilization indication to control harvester speed for optimum productivity. Comparing relative pressure readings at more than one location in the air system can reduce system warning response time and increase sensitivity for certain blockage or overload conditions. The pressure monitor system  80 , in combination with drive shaft monitoring on the processor  38  to provide an indication of the shaft speed and/or loading of the processor, assures that a potential overload or blockage anywhere between the auger  26  and the outlet area  40  is timely and reliably detected. Harvester speed can be adjusted easily to maintain duct capacity usage close to the maximum duct capacity.  
         [0017]     In a further embodiment of the invention, the controller  70  also controls machine harvest speed automatically. The controller  70  is connected to an operator speed control  90  and controls a hydrostatic transmission  94  connected to the drive wheels  16 . The controller  70  is responsive to the speed control  90  and to the load indicating signals provided by one or more of the monitors  60 ,  62  and  64  and by the pressure monitor  82  and any additional monitors on the drive or air system. In an automatic speed control mode, the controller  70  causes the harvester to move at a speed up to the maximum speed determined by the setting of the speed control and by the capacity indications. Maximum set speed will be maintained if the capacity indications from the processor  38  and the duct structure  30  are all within acceptable ranges. However, if the controller  70  determines that a maximum capacity condition is approached or reached at either the duct structure  30  or the on-board processor  38 , the controller  70  causes the harvester  10  to slow as necessary to alleviate the potential overload or blockage condition and to maintain the monitor signals within their desired ranges. If the bypass grate structure  34  is moved to bypass the processor  38  so harvested material is propelled directly from the duct structure  30  through the outlet area  40  into the basket, the controller  70  in the automatic speed control mode adjusts harvester speed up to the maximum speed set by the control  90  and assures that maximum duct capacity is not exceeded. The controller  70  can provide an indication to the operator when both the processor and duct capacities are consistently below maximum allowable so that the setting of the upper limit set by speed control  90  can be increased if field conditions permit.  
         [0018]     Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.