Abstract:
A snow removal vehicle is provided comprising an impeller, an engine system, and an engine control system. The engine control system receives feedback information pertaining to operation of the impeller, and controls the engine system based on the feedback information. A method of controlling a snow removal vehicle is provided comprising acquiring feedback information pertaining to operation of an impeller of the snow removal vehicle, analyzing the feedback information with an electronic signal processor, and controlling forward movement of the snow removal vehicle based on the feedback information.

Description:
FIELD OF THE INVENTION 
     The field of the invention is snow removal vehicles. More particularly, the invention relates to a control system and method for a snow removal vehicle. 
     Snow removal vehicles are commonly employed for removing snow in, for example, municipal and commercial settings. A common type of snow removal vehicle, which is commonly referred to as a “snow blower” vehicle, comprises an impeller or ribbon which is mounted at the front of the vehicle and which is driven by an engine to throw or “blow” snow away from a region of interest. For example, at airports, snow plows are employed to initially plow snow to the side of runways, and then one or more snow blower vehicles are employed to throw the snow further away from the side of the runway (e.g., several hundred feet from the side of the runway). This prevents snow banks from building up along the side of the runway which would hamper further snow removal efforts. 
     For efficient resource utilization, it is desirable for snow removal vehicles to be able to remove as much snow as possible in as little time as possible. As used herein, the term “efficiency” refers to the amount of snow per unit time (e.g., tons per hour) that a snow removal vehicle is capable of removing. If the vehicle progresses too slowly, then snow intake is reduced and therefore vehicle efficiency is reduced. If the vehicle progresses too quickly, then snow intake exceeds the snow removal capacity of the snow removal vehicle, thereby causing the impeller to stall and causing vehicle efficiency to be reduced to zero until the impeller is cleared. 
     In practice, it is often difficult for an operator of a snow removal vehicle to operate the snow removal vehicle at maximum efficiency due to varying snow conditions. As the vehicle moves forward, the vehicle is likely to encounter snow of varying density due to variations in snow packing, snow wetness, drifting and so on. Additionally, the operator may encounter patches that have been previously cleared of snow, allowing the vehicle to travel forward much faster. The varying snow conditions affect the rate at which snow can be removed without impeller stalling. What is needed therefore is a control system and method for a snow removal vehicle that can be used to optimize vehicle efficiency. 
     SUMMARY OF THE INVENTION 
     According to a first preferred aspect of the invention, a snow removal vehicle is provided comprising an impeller, an engine system, and an engine control system. The engine control system receives feedback information pertaining to operation of the impeller, and controls the engine system based on the feedback information. 
     According to a second preferred aspect of the invention, a method of controlling a snow removal vehicle is provided. The method comprises acquiring feedback information pertaining to operation of an impeller of the snow removal vehicle, analyzing the feedback information with an electronic signal processor, and controlling forward movement of the snow removal vehicle based on the feedback information. 
     Other objects, features, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and accompanying drawings. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration and not limitation. Many modifications and changes within the scope of the present invention may be made without departing from the spirit thereof, and the invention includes all such modifications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A preferred exemplary embodiment of the invention is illustrated in the accompanying drawings in which like reference numerals represent like parts throughout, and in which: 
     FIG. 1 is a schematic view of a snow removal vehicle with a control system according to a preferred embodiment of the invention; 
     FIG. 2 is a block diagram showing the control system of FIG. 1 in greater detail; 
     FIG. 3 shows a display of the control system of FIG. 1 in greater detail; and 
     FIG. 4 is a signal flow diagram showing the operation of the control system of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to FIG. 1, a schematic diagram of a snow removal vehicle  10  is illustrated. The snow removal vehicle  10  comprises a plurality of drive wheels  12 , an impeller  14 , an engine system  16  that drives the drive wheels  12  and the impeller  14 , and an engine control system  18  that controls the engine system  16 . 
     The components  12 - 18  are shown in greater detail in FIG.  2 . Referring now to FIG. 2, the engine system  16  preferably includes separate engines for the drive wheels  12  and the impeller  14 . Thus, the drive wheels  12  are coupled to and are driven by a traction engine  20 , and the impeller  14  is coupled to and is driven by an impeller engine  22 . Of course, it would also be possible for the engine system  16  to comprise only a single engine that drives both the drive wheels  12  and the impeller  14 , or to comprise more than two engines working in tandem. However, the use of two engines is the preferred arrangement. 
     The control system  18  further includes a plurality of electronic control units  24 - 28 , a network communication link  30  that couples the electronic control units  24 - 28 , a throttle  32 , an impeller sensor  34 , and an operator interface  36 . The electronic control unit (ECU)  24  is coupled to the traction engine  20  and therefore is referred to hereafter as the traction engine ECU. The traction engine ECU  24  controls the operation of the traction engine  20 , and is coupled to a throttle  32  used to acquire an operator input pertaining to the speed and acceleration conditions desired by the operator. The throttle  32  may be provided in the form of a floor-mounted throttle pedal. In FIG. 2, the throttle  32  is shown to be coupled to the traction engine ECU  24  by way of the communication link  30  which may, for example, be an SAE (Society of Automotive Engineers) J1939 communication link. However, the throttle  32  could also be hardwired to the traction engine ECU  24 . 
     The ECU  26  is coupled to the impeller engine  22 , and therefore is referred to hereafter as the impeller engine ECU. The impeller engine ECU  26  controls the operation of the impeller engine  22  which drives the impeller  14 . 
     The ECU  28  is coupled to the traction engine ECU  24  and the impeller engine ECU  26  by way of the communication link  30 , and provides for overall control of the engines  20  and  22 . The ECU  28  is hereafter referred to as the snow removal system ECU or system ECU. Conceivably, rather than using three separate electronic control units, it would also be possible to use a smaller or larger number of electronic control units. Commercially available engines are typically provided with electronic control units, however, and it is desirable for sake of convenience to simply use the electronic control units provided by the manufacturer with the engines  20  and  22  and to implement additional functionality via an additional ECU in the manner illustrated. Electronic control units provided by engine manufacturers are typically microprocessor-based devices that include a control program (not illustrated) that is executable to control the associated engine, and that are capable of being coupled to a network communication link (e.g., J1939) to interface with other vehicle devices. 
     The system ECU  28  is coupled to an impeller sensor  34  which is used to acquire information pertaining to the operation of the impeller  14 . For example, the impeller sensor  34  may be a pressure transducer that is coupled to sense pressure within a hydraulic system that couples the impeller engine  22  to the impeller  14 . Again, in FIG. 2, the sensor  34  is shown to be coupled to the system ECU  24  by way of the network communication link  30 . However, the impeller sensor  34  could also be hardwired to the system ECU  28 . 
     The system ECU  28  is also coupled to an operator interface  36  by way of a hardwired communication link  38 , which in practice may comprise individual wires connected to respective input/output devices (switches/indicators) which form the operator interface  36 . Referring now to FIG. 3, the operator interface  36  is shown in greater detail. The operator interface  36 , which may be mounted in an operator compartment  39  of the vehicle  10 , preferably comprises a switch  50  and a plurality of indicators  52 - 64 . The switch  50  is an on/off switch and controls whether the control system  18  is engaged, giving the operator the option to disengage the control system  18  and operate the vehicle  10  without the aid of the control system  18 . The indicators  52 - 64  are preferably light emitting diodes (LEDs). The indicator  52  indicates whether the switch  50  is on or off, that is, whether the control system  18  is engaged or on-line. The remaining indicators  54 - 64  are discussed in greater detail in conjunction with signal flow diagram of FIG.  4 . 
     In practice, the system ECU  28  is preferably a microprocessor-based device that executes a control program  29 . The system ECU  28  includes a communication interface (e.g., a plurality of discrete inputs and outputs) for connection to the hardwired communication link  38  that connects the system ECU  28  with the operator interface  36 . The system ECU  28  also includes a communication interface for connection to the network communication link  30 . 
     Referring now to FIG. 4, a signal flow diagram showing the operation of the control unit  28  is illustrated. The signal processing that is shown in FIG. 3 is implemented by way of execution of the control program  29 . The control program  29  is used to maintain the snow removal vehicle  10  operating at maximum efficiency. To this end, the control program  29  preferably operates to cause the snow removal vehicle  10  to move forward in accordance with the throttle command provided by the operator during normal operating conditions, but operates to reduce the throttle command provided by the operator when necessary to avoid impeller stall conditions. 
     The control program  29  receives inputs from three sources. The first input, received at block  100 , is a first feedback parameter pertaining to a first operational parameter of the impeller  14 . The first feedback parameter preferably pertains to the impeller engine  22 , for example, percent engine loading. In this event, the feedback information may be acquired from the impeller engine control unit  26  upon being queried for such information by the system ECU  28 . The impeller engine feedback information is then provided to an error checking block  102  in which error checking is performed to ensure that the feedback information received from the impeller engine control unit  26  is valid. For example, the error checking may be performed based upon recent previous feedback information received from the impeller engine control unit  26  for the same parameter and/or based on other known operational limits. If the impeller sensor malfunctions, the control system  18  still operates but it only makes decisions based on the percent engine loading. 
     The feedback information from the error checking block  102  is transmitted to a data logging block  104  and an operator alert block  106 . The data logging block  104  stores feedback information at frequent, periodic intervals to maintain a running log of the feedback information and thereby promote system troubleshooting should such troubleshooting be necessary. If desired, the running log may also store information pertaining to other parameters of either the traction engine  20  or the impeller engine  22  after appropriate error checking as previously described. 
     The operator alert block  106  notifies the operator if the error checking block  102  detects an error in the feedback information received from the impeller engine control unit  26 . The operator alert is provided by way of the engine error indicator  62  located on the operator interface  36 . Thus, if the impeller engine ECU  26  stops providing valid percent engine loading information, the error indicator  62  will illuminate. 
     After the error checking is performed at block  102 , signal conditioning is performed at block  108 . The signal conditioning at block  108  conditions the information received at block  100 , for example, to implement averaging or hysteresis functions. 
     The second input to the control program  29 , received at block  110 , is a second feedback parameter pertaining to a second operational parameter of the impeller  14 . Preferably, the second operational parameter pertains to a pressure sensed in a hydraulic system that couples the impeller engine  22  to the impeller  14 . In this event, the impeller sensor  34  is a pressure sensor from which the sensed pressure is received at block  116 . 
     Error checking is performed at block  112  in the same manner as described in connection with block  102 , with the output of the error checking block  112  being provided to the data logging block  104  and the operator alert block  106 . In this case, the operator alert block  106  notifies the operator if the error checking block  102  detects an error in the feedback information received from the impeller sensor  34 . The operator alert is provided by way of the impeller error indicator  64  located on the operator interface  36 . Thus, if it is determined that the impeller sensor  34  is not providing valid hydraulic pressure information, the error indicator  64  will illuminate. Signal conditioning is performed at block  114  to convert the voltage signal provided by the impeller sensor  34  into a format that has units of pounds per square inch. 
     In addition to or instead of hydraulic pressure and percent engine pressure, other parameters could also be acquired and used as feedback parameters. For example, the torque applied by the impeller engine  22  in driving the impeller  14  could be used by implementing the impeller sensor  34  in the form of a toque sensor rather than a pressure sensor. Alternatively, the angular velocity (e.g., revolutions per minute) of the impeller  14  could be used as a feedback parameter by querying the impeller engine ECU  26  for velocity information. It should also be apparent that any combination of feedback from ECUs and discrete sensors is possible. 
     The third input to the control program  29 , received at block  115 , is an operator throttle command received from the throttle  32 . As previously indicated, the control program  29  preferably provides the traction engine ECU  24  with the full throttle command provided by the operator during normal operating conditions, but operates to provide the traction engine ECU  24  with a reduced throttle command when necessary to prevent impeller stall conditions. (For safety reasons, it is typically desirable to limit the speed of the snow removal vehicle  10  to that speed commanded by the operator by way of the throttle  32 .) This portion of the control program is implemented at blocks  116 - 120 . 
     The decision block  116  receives the error-checked, reformatted feedback signals from the input blocks  100  and  110 . At the decision block  116 , the feedback signals are analyzed and it is determined whether to modify the operation of the engine system  16  based on the received feedback information and, in particular, whether to reduce (or otherwise modify) the throttle command provided by the operator. 
     This determination is made by ascertaining whether either of he first and second feedback parameters exceeds a predefined threshold. For example, percent engine loading of the impeller engine  22  is one stall condition that may be monitored. Thus, the decision block  116  may decide to reduce the throttle command if the percent engine loading exceeds a predetermined level. By way of example, a level that is within the range of ninety to ninety-seven percent (e.g., 95%) may be chosen. 
     Likewise, hydraulic systems typically have a relief valve set at a known pressure. For example, if the relief valve is set at 5000 psi, thereby establishing 5000 psi as an impeller stall condition, then 4500 psi may be chosen as the predefined threshold. In this event, it is determined at decision block  116  to modify the throttle command if hydraulic pressure meets or exceeds 4500 psi. 
     Assuming it is determined at decision block  116  to reduce the throttle command provided to the traction engine ECU  24  by the operator, then the signal shaping block  118  generates a command to reduce the throttle command by a predetermined percentage. The throttle command produced by the signal shaping block  118  is a command that is recognizable by the traction engine ECU  24  as a throttle command input. Thus, when it is determined that the snow removal vehicle  10  is operating near one or more impeller stall conditions (e.g., percent engine loading too high, or hydraulic pressure too high), the throttle command is automatically reduced by a predetermined percentage to avoid impeller stalling. If the first throttle reduction is not sufficient, then further iterations of this process occur until the vehicle  10  is brought to an operating point that is below impeller stall conditions (e.g., below 95 percent engine loading and below 4500 psi hydraulic pressure). When none of the feedback parameters indicates that the vehicle is near impeller stalling, then the output of the signal conditioning block  118  is simply a null signal. 
     At the decision block  120 , either the throttle command from either the throttle  32  or the throttle command from the signal shaping block  118  is selected. If the throttle command from the signal shaping block  118  is active, then it is selected. Otherwise, if the throttle command from the signal shaping block  118  is null, then the throttle command from the throttle  32  is selected. 
     At block  122 , the throttle command output of the block  120  is transmitted to and utilized by the traction engine ECU  24 . Assuming that the output of the signal shaping block  118  is active, then the forward velocity of the snow removal vehicle  10  is reduced. In turn, this reduces the snow intake rate into the impeller  14  which thereby avoids impeller stalling. The control system  18  then continues to monitor vehicle status and continues to decrease the throttle command as necessary until the impeller is no longer at or near stall conditions. 
     System status during this process may be displayed to the operator by way of the operator interface  36 . The indicators  56 - 60  are impeller status indicators. For example, the indicator  56  may be a green indicator, indicating that impeller  14  is in an acceptable operating region and is not in danger of stalling. The indicator  58  may be a yellow indicator and may indicate that the impeller  14  is nearing stall conditions (e.g., hydraulic pressure above 4500 psi and/or percent engine loading above 95 percent). The indicator  60  may be a red indicator and may indicate that impeller  14  is at or above a stall condition (e.g., hydraulic pressure above 5000 psi or percent engine load above one-hundred percent). The indicator  54  indicates whether the control system is in an active mode in which the control system is reducing the throttle command provided to the traction engine control unit  24  to avoid impeller stalling. Typically, the indicators  54  and  58  or  54  and  60  illuminate concurrently. In this regard, it may be noted that it is sometimes possible for a snow removal vehicle to operate for short periods of time even though impeller stall conditions have been met, so long as the impeller stall conditions are not met for extended durations. 
     The preferred embodiment described herein improves the operation of snow removal vehicles by maintaining vehicle operation such that the vehicle removes the maximum amount of snow that it is capable of removing, while avoiding the risk of the impeller stalling. This allows snow removal vehicles to remove more snow per hour, that is, to operate at maximum efficiency. 
     Many other changes and modifications may be made to the present invention without departing from the spirit thereof. The scope of these and other changes will become apparent from the appended claims.