Abstract:
A forage harvester represents agricultural implements that include at least one rotating component which is driven through a drive train including a main clutch operable between engaged and disengaged conditions so as to selectively couple and disconnect an output of the implement power source with the rotatable component. A rotation alarm circuit is provided for causing a warning device or devices to be energized in the event that the operator leaves a seat, in which he sits for normal operation, for a predetermined minimum time period while the rotatable component is still rotating, as determined by a rotation sensor. The warning device will remain energized until the rotatable component spins down to a zero speed.

Description:
FIELD OF THE INVENTION 
     The present invention relates to agricultural implements, and more specifically relates to such implements as have rotational components located remotely from an operator&#39;s station associated either with the implement itself or with a vehicle towing the implement. 
     BACKGROUND OF THE INVENTION 
     The functional elements of agricultural crop harvesters include some that are relatively massive and driven in rotation. When the power for driving these components is disconnected by an action of the operator, the operator is apt to believe that the rotation of the component has stopped, when in fact, the inertia of the component causes it to continue to rotate. This rotation will sometimes continue for several minutes, which is beyond the time that it takes for an operator to leave the operator&#39;s station and remove shielding extending about, or open an access door of a housing containing, the component, thus exposing the operator to danger. 
     U.S. Pat. No. 4,843,767 discloses one example of a harvester having rotating components which are remotely controlled by an operator and which may possibly operate so as to give rise to the above-described problem. 
     U.S. Pat. No. 4,974,711 discloses a brake and clutch control system for the power take-off of a lawn and garden tractor that may be equipped with a mower coupled to the tractor power take-off. The control system may embody a seat switch that acts to cause the power take-off control clutch to be disengaged and the brake to be engaged in the event that the operator leaves the seat. While such a system ensures that the operator will not accidentally come into contact with the rotating mower blades, a practical system for reliably stopping the spin down of large inertia components is not yet available. 
     U.S. Pat. No. 5,132,327 discloses a control system for warning an operator of the continued rotation of a spindle for a machine, such as a wood working machine, due to the inertia of the spindle after a motor for rotating the spindle is shut off. In this control system, the location of the operator is not taken into account and the warning device is a light which is normally lit when the drive motor is operating so the operator may not pay attention to it after the power to the motor is discontinued. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided an improved warning system for use with agricultural implements embodying rotatably driven components, for example, forage harvesters, combines, cotton harvesters and the like. 
     An object of the invention is to provide a warning system, incorporated in the component drive control system, so as to reduce the likelihood of an operator coming into contact with a rotating component of the implement after the operator has disconnected the power to the component. 
     A more specific object of the invention is to provide an electrical safety interlock circuit which includes an operator presence sensor and a component rotation sensor having respective outputs coupled to a circuit for controlling operation of a warning device, the circuit operating to activate the warning device if the operator, after disengaging power to the rotating component, leaves the operator&#39;s seat while the component is still rotating. 
     Yet a more specific object of the invention is to provide a safety interlock circuit, as stated in the immediately preceding object, wherein a count-up timer device is provided which prevents actuation of the warning device in the event that the operator leaves the operator seat only momentarily. 
     Another specific object of the invention is to provide a safety interlock circuit, as stated in one or more of the preceding objects, wherein the circuit contains a timer circuit which times out to cause the warning device to be turned off only upon the expiration of a time sufficient for the rotating component to spin down. 
     A further object of the invention is to provide a safety interlock circuit, as stated in one or more of the preceding objects, wherein the warning device is kept from being activated when the circuit receives a signal indicative of the operator intentionally selecting a mode of powered operation before leaving the operator seat. 
     These and other objects of the invention will become apparent from a reading of the ensuing description together with the appended drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic top view of a self-propelled agricultural harvester with which the present invention has utility. 
     FIG. 2 is schematic diagram of the rotation alarm circuit adapted for use with the harvester illustrated in FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1 there is shown a self-propelled forage harvester  10 , which is representative of the environment in which the present invention is particularly useful, it to be understood that the invention would also be adaptable for use with other harvesters or implements such as combines, cotton pickers and balers, for example. The harvester  10  includes a main frame  12  supported for being driven over the ground on a pair of front drive wheels  14  and a pair of rear steerable wheels  16 . Coupled to the front of the frame  12 , so as to be in view of an operator seated in a cab (not shown) mounted to the front of the frame  12 , is a crop gathering head  18  which delivers crop to the rear where it passes between upper and lower sets of counter-rotating feed rolls  20  and  22  which act to compress the crop into a mat and feed the mat across a stationary cutter bar (not shown). A cutterhead or chopper drum  24  is mounted in such relationship to the cutter bar that its knives sweep past the cutter bar and cut the mat of crop into short pieces. The cutterhead  24  delivers the cut crop tangentially to a bite of a pair of counter-rotating processing rolls  26 , that in turn deliver the crop to a blower  28 . The blower  28  is located in a housing  29  that converges to an outlet  30  to which is coupled a discharge duct (not shown), the blower  28  operating to propel the crop through the discharge duct, which directs the chopped crop to a container (not shown), such as a towed trailer, for example. 
     The drive wheels  14  and other driven components of the harvester receive their power from an engine  32  mounted on the rear of the frame  12 . A power splitter transmission  34  is coupled to an output shaft at a front end of the engine  32  and contains a bevel gear set which delivers power to a transverse shaft  35  carrying an electronically controlled, hydraulically actuated main drive clutch  36 , and to a longitudinal shaft coupled to a service hydraulic pump  38 . 
     A main drive arrangement for the crop processing components of the forage harvester  10  includes a main drive pulley  40  coupled to an output side of the main drive clutch  36 , and cutterhead and blower drive pulleys  42  and  44 , respectively, coupled to cutterhead and blower drive shafts  46  and  48 . A drive belt arrangement  50  is trained about the pulleys  40 ,  42  and  44 . 
     Mounted at the left side of a housing containing the feed rolls  20  and  22 , and the cutterhead  24  is a feed roll gear box or transmission  52  having respective output shafts coupled to the feed rolls  20  and  22  and an input shaft coupled to the cutterhead shaft  46  by way of a conventional electrically operated clutch  54 . A one-way hydraulic reverser motor  56  is coupled to an input shaft of the gear box  52  for driving the cutterhead  24  in reverse for knife sharpening. The motor  56  is powered by hydraulic fluid pressure supplied from the pump  38  and communicated to the motor  56  by a solenoid operated valve  58 . A solenoid-operated, main clutch control valve  60  controls fluid communication between the pump  38  and the main drive clutch  36 . 
     A feed roll FNR switch  62  is connected to the valves  58  and  60  by respective leads  64  and  66 , and to the clutch  54  by a lead  68 , so that an operator can actuate the switch  62  to disengage the main clutch  36 , engage the clutch  54  and cause the motor  56  to drive the cutterhead  24  in reverse as is required during knife sharpening. If the clutch  54  is disengaged, the feed rolls  20  and  22  will rotate in reverse so as to back out obstructions, for example. 
     Referring now to FIG. 2, there is shown an electrical rotation alarm or warning circuit  70 , here shown as a logic circuit, that is adapted for use with the forage harvester  10 , with it to be understood that a circuit embodying the principles of the circuit  70  may just as easily be adapted to other agricultural harvesters or implements having rotating components that operate such as to need a warning circuit. The warning circuit  70  includes a  12  volt supply source coupled to a power lead  72  and to an ignition switch  73  coupled to a seat switch lead  74  containing a seat switch  76  that is biased to a normally open position, as shown, when an operator is absent from the operator&#39;s seat. The switch  73  is but one way of sensing the presence of the operator, with optical or other types of sensors being possible just so long as they produce a signal indicating the presence, or lack of same of the operator. The output of the seat switch  76  is coupled to an inverter  78  having its output parallel-connected to first input terminals of first and second AND gates  80  and  82 , respectively. 
     Coupled to the power lead  72  is a lead  84  containing four switches connected in series, namely a main clutch control switch  86 , a metal detector system ON/OFF switch  88 , The feed roll FNR switch  62  and a reverse motor pressure switch  92 . The contact of the pressure switch  92  has a parallel connection with a second input of the first AND gate  80  and with a second inverter  94 , the latter having its output coupled to a second input of the second AND gate  82 . Outputs of the first and second AND gates  80  and  82  are respectively coupled to inputs of first and second count-up timer circuits  96  and  98  having respective outputs coupled to first and second inputs of an OR gate  100  having its output, in turn, coupled to a first input of a third AND gate  102 . While other time limits may be used, the practical example disclosed here uses a 6 second time period for the circuit  96  and a 3 second time period for the circuit  98 . 
     Another lead  104  is connected to the power lead  72  and contains a power-saver switch  106  (closed during knife-grinding operation, for example) having its output terminal coupled to a third inverter  108 , which in turn has its output terminal connected to a second input terminal of the AND gate  102 . 
     A further lead  110  is connected to the output of the ignition switch  73  in parallel with the seat switch power lead  74 , the lead  110  being connected to a third input of the third AND gate  102 . 
     A cutterhead rotation sensor  112 , is associated with the cutterhead drive shaft  46 . As long as the critical driven components all derive their rotation in series with the cutterhead  24 , as shown in FIG. 1, only one rotation sensor is required. Further, the rotation sensor  112  can be an electric, electromagnetic or optical movement sensor, with the only requirement being that the sensor output an electric signal. While rotation sensors having different characteristics may be used, in one practical example, the sensor  112  is a variable reluctance speed sensor having a lower speed sensing capability of about 300 rpm. Therefore, the sensor  112  is coupled to a time delay circuit  113  that processes the pulses received from the sensor such that it maintains a high output for so long as the rotation is above 300 rpm and for a programmed time duration thereafter, for a purpose explained more fully below. An output of the time delay circuit  113  is coupled to a fourth input terminal of the third AND gate  102 , a first input of a fourth AND gate  114  and a first input of a third OR gate  116 . The output of the AND gate  102  is coupled to a first input of a second OR gate  118 . 
     Another lead  120  is connected between the ignition switch  73  and a fourth inverter  122  having its output connected to a second input of the fourth AND gate  114 . The output of the AND gate  114  is connected to a second input of the second OR gate  118 , the output of which is connected to an audible warning device, such as a horn  126  that is mounted in the vicinity of the cutterhead  24 . Of course multiple warning devices could be used and distributed about the forage harvester  10  where desired. A lead  130  is also connected between the ignition switch  73  and a second input terminal of the third OR gate  116  having its output coupled to a count-down or power down timer circuit  132  having its output coupled to an electronics power lead  134 , and being for the purpose of turning off the power to the control circuit after an elapse of time, 60 seconds, for example, after the harvester  10  is shut off and the horn has stopped sounding. 
     The operation of the control circuit  70  is as follows. Assume a condition of operation where the ignition switch  73  is ON, the operator is seated and the main clutch control switch  86  is ON, with the cutterhead  24  and blower  28  being driven in the forward direction. Under this condition, the seat switch  76 , main clutch control switch  86 , metal detector switch  88 , FNR switch  62  and the reverse motor pressure switch  92  will all be closed. This results in the input to the first inverter  78  being high, with its output, and hence, the first inputs of the first and second AND gates  80  and  82  being low. The signal over the lead  84  will also be high, so the second input to the first AND gate  80  will be high, resulting in the output from the AND gate  80  being low. Accordingly, the count-up timer circuit  96  will be reset to zero and its output will be low. 
     The high signal on the lead  84  will also be connected to the input of the second inverter  94 , with its low output being coupled to the second input of the second AND gate  82 . With both inputs to the second AND gate  82  being low, its output will be low. Accordingly, the count-up timer circuit  98  will be reset to zero and its output will be low. With the outputs of both count-up timer circuits  96  and  98  being low and fed as inputs to the first OR gate  100 , the output of the OR gate  100  will be low, as will be the first input to the third AND gate  102 . The power saver switch  106  will be open so the signal at the input to the inverter  108  will be low with its output being high so that the second input of the AND gate  102  is high. The high output of the ignition switch  73  is connected directly to the third input of the third AND gate  102 . The cutterhead rotation sensor  112  supplies pulses to the time delay circuit  113 , which acts to provide a high signal to the final input of the third AND gate  102 , as well as high inputs to each of the fourth AND gate  114  and the third OR gate  116 . Because one of the inputs to the AND gate  102  is low, its output will be low, thus supplying a low signal to one of the inputs to the second OR gate  118 . The signal coupled to the input of the fourth inverter  122  is high, resulting in its output being low and the input to the fourth AND gate  114  being low. The low output from the AND gate  114  is connected to the second terminal of the third OR gate  118 . Thus, the output of the OR gate  118  is low and the horn  126  does not sound. Both inputs to the third OR gate  116  are high so the count-down timer circuit  132  is reset to the timeout value. Its output is high at this point, so the power to the control circuit  70  remains on. 
     Assume next a condition the same as the above, except that the operator has left the seat so that the seat switch  76  is open, and the main clutch control switch  84  is likewise open or OFF. The inverter  78  will cause first inputs of the AND gates  80  and  82  to be high, while the second input to the AND gate  80  will be low and the second input to the AND gate  82  will be high. Thus, the count-up timer circuit  96  will not be started, but the count-up timer circuit  98  will be started. Assuming that the operator remains out of the seat for at least 3 seconds, the output of the count-up timer circuit  98  will go high, resulting in one of the inputs to the OR gate  100  being low and the other high resulting in a high output, which is at the first input of the AND gate  102 . The pressure switch  106  is open so the inverter  108  passes on a second high signal to the AND gate  102 . The third lead  110  connects a third high signal to the AND gate  102  and the rotation sensor  112  acts to activate the time delay circuit  113  which passes on a high output signal to the fourth input to the AND gate  102 . With all the inputs to the AND gate  102  being high, it passes a high signal to one input of the OR gate  118 , and because of this, it sends on a high signal which causes the horn  126  to sound. 
     If the ignition switch  73  is turned off, no different result is obtained. Specifically, the input to the inverter  78  is still low and a low signal is coupled over the lead  110  to the input of the AND gate  102 . Therefore, the input to the OR gate  118  will be low. The inverter  122  will now receive a low input and operate to place a high signal at the input to the input of the AND gate  114 . So long as the cutterhead is still spinning, a high signal will pass from the time delay circuit  113  to the other input of the AND gate  114 , resulting in a high signal being received by the OR gate  118  and output to the horn  126  to cause it to sound. 
     The time delay circuit  113  will continue to have a high output until the rotation speed of the cutterhead  24  falls below the accuracy limit of the sensor  112 , in this case 300 rpm. At this point the time delay of the circuit  113  will be triggered and the output signal will continue to be high until the circuit  113  times out, at which time the output will go low, causing the horn  126  to be turned off. 
     With the ignition switch  73  open and the output of the time delay circuit  113  low, a low signal will be placed on an input of each of the third AND gate  102 , fourth AND gate  114  and third OR gate  116 . Because the input of the inverter  122  will be low, it again acts to place a high signal at the input to the AND gate  114 . Since an input to the AND gate  114  is low, its output is low and is connected to one input of the OR gate  118 . A low input will be connected to the count-down timer circuit  132  which will cause it to begin to count down. After the circuit times down to zero, its output will go low resulting in the power to the control circuit  70  being turned off so as to not run the battery down. 
     Assuming that it is desired to power the cutterhead  24  in reverse for sharpening its blades, the operator will deliberately actuate the FNR switch  62  so as to cause the main clutch  36  to be disengaged, the clutch  54  to be engaged and the motor  56  to operate to drive the cutterhead  24  in reverse. Further assume that the operator has left the seat. In this case, the seat switch  76  will be open resulting in a high signal appearing at the input to the AND gate  80 . Also, the main clutch switch  86 , the metal detector switch  88  and the FNR switch  62  will be open while the reverse motor pressure switch  92  will be closed. This results in a low signal being received by the other input of the AND gate  80  so that it sends a low signal to the count-up timer circuit  96  to cause it to reset to zero and send a low signal to one input of the OR gate  100 . A high signal will be present at both inputs to the AND gate  82 , resulting in the input to the count-up timer circuit  98  being high. After three seconds, the circuit  98  will send a high signal to the input of the OR gate  100  which will operate to place a high signal at one input to the AND gate  102 . The power saver switch  106  will be closed and will pass on a high signal to the inverter  108  which acts to place a low signal at the input to the AND gate  102 . No matter what the other inputs to the AND gate  102  are, its output is low resulting in the input to the OR gate  118  being low. The output of the inverter  122  and, hence, the input to the AND gate  114  is low. Accordingly, the output to the OR gate  118  is low. Since both inputs to the OR gate  118  are low, the horn  126  will not sound. 
     Thus, the logic elements of the circuit  70  act to warn the operator of continued rotation of a driven component after the operator has taken steps to disconnect power to the driven component, but prevent the warning device to be activated when the operator takes deliberate steps to connect power for driving the driven component. 
     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.