Control system and method for a snow removal vehicle

Information

  • Patent Grant
  • 6266598
  • Patent Number
    6,266,598
  • Date Filed
    Thursday, May 4, 2000
    24 years ago
  • Date Issued
    Tuesday, July 24, 2001
    22 years ago
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.



Claims
  • 1. A snow removal vehicle comprising:an impeller; an engine system; and an engine control system, said engine control system receiving feedback information pertaining to operation of said impeller, said engine control system controlling said engine system based on said feedback information, said engine control system comprising a microprocessor-based control unit, and wherein said feedback information is obtained from said microprocessor-based control unit.
  • 2. A snow removal vehicle according to claim 1, wherein said engine control system controls said engine system based on said feedback information to avoid stalling of said impeller.
  • 3. A snow removal vehicle according to claim 2, wherein said engine control system causes said engine system to reduce a forward velocity of said snow removal vehicle to avoid stalling of said impeller.
  • 4. A snow removal vehicle according to claim 2, wherein said engine control system causes said engine system to drive forward movement of said snow removal vehicle in accordance with a throttle command provided by an operator when said snow removal vehicle is not operating near an impeller stall condition, and operates to provide a throttle command less than that provided by the operator when necessary to avoid impeller stall conditions.
  • 5. A snow removal vehicle according to claim 1, wherein said feedback information is obtained from a pressure censor that senses a pressure within a hydraulic system that is coupled between said engine system and said impeller.
  • 6. A snow removal vehicle comprising:an impeller; an engine system, said engine system including a traction engine, said traction engine being coupled to drive wheels of said snow removal vehicle, and said traction engine being adapted to drive said drive wheels to drive movement of said snow removal vehicle, and an impeller engine, said impeller engine being coupled to said impeller, and said impeller engine being adapted to drive said impeller to drive snow removal; and an engine control system, said engine control system receiving feedback information pertaining to operation of said impeller, and said engine control system controlling said engine system based on said feedback information, said engine control system including a network communication link, a microprocessor-based traction engine control unit, said traction engine control unit being coupled to said traction engine and being adapted to control said traction engine, a microprocessor-based impeller engine control unit, said impeller engine control unit being coupled to said impeller engine and being adapted to control said impeller engine, and a microprocessor-based system control unit, said system control unit being coupled to said traction engine control unit and said impeller engine control unit by way of said network communication link, said system control unit being adapted to receive said feedback information pertaining to said operation of said impeller, and to generate a control signal for said traction engine control unit based on said feedback information.
  • 7. A snow removal vehicle according to claim 6, wherein said feedback information is received from said impeller engine control unit.
  • 8. A snow removal vehicle according to claim 6, wherein said feedback information pertains to percent engine loading of said impeller engine.
  • 9. A snow removal vehicle according to claim 6, wherein said feedback information pertains to a torque applied by said impeller engine.
  • 10. A snow removal vehicle according to claim 6, wherein said feedback information pertains to an angular velocity of said impeller engine.
  • 11. A snow removal vehicle according to claim 6, wherein said snow removal vehicle is a driver-operated vehicle and includes a driver compartment that is adapted to carry a human driver that operates said snow removal vehicle.
  • 12. A snow removal vehicle according to claim 6, wherein said engine system drives forward movement of said snow removal vehicle and wherein said engine control system controls forward movement of said snow removal vehicle based on said feedback information.
  • 13. A method of controlling a snow removal vehicle comprising:acquiring feedback information pertaining to operation of an impeller of said snow removal vehicle; analyzing said feedback information with an electronic signal processor; and controlling forward movement of said snow removal vehicle based on said feedback information.
  • 14. A method according to claim 13 wherein, during said controlling step, a rate of said forward movement of said snow removal vehicle is reduced to avoid impeller stalling in response to said feedback information indicating that said snow removal vehicle is operating near an impeller stall condition.
  • 15. A method according to claim 14, wherein said feedback information pertains to loading of an engine that drives said impeller.
  • 16. A method according to claim 14, wherein said feedback information pertains to pressure in a hydraulic system that is coupled between said impeller and an impeller engine.
  • 17. A method according to claim 14, wherein said feedback information pertains to a torque applied by an engine that drives said impeller.
  • 18. A method according to claim 14, wherein said feedback information pertains to an angular velocity of an engine that drives said impeller.
  • 19. A method of controlling a snow removal vehicle comprising:acquiring feedback information pertaining to operation of an impeller of said snow removal vehicle; transmitting said feedback information to a microprocessor-based system control unit; processing said feedback information at said system control unit, including determining that said feedback information indicates that said impeller is operating near a stall condition; and reducing a rate of forward movement of said snow removal vehicle in response to said feedback information indicating that said impeller is operating near said stall condition, including generating, at said system control unit, a control signal microprocessor-based traction engine control unit, said traction engine control unit being coupled to and controlling an engine that drives forward movement of said snow removal vehicle, transmitting said control signal from said system control unit to said traction engine control unit by way of a network communication link, and utilizing said control signal at said traction engine control unit to reduce said rate of said forward movement of said snow removal vehicle.
  • 20. A method according to claim 19, wherein said feedback information is acquired from a microprocessor-based impeller engine control unit that is coupled to and controls an engine that drives said impeller, and wherein said feedback information is transmitted by way of said network communication link.
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Number Date Country
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