This invention relates to machine performance optimization for off-highway vehicles. In particular this invention utilizes the ability to command a maximum torque limit for a drivetrain to optimize machine performance.
In a typical wheel loader vehicle the ratio of power split between the drivetrain and the hydraulic system is governed by a typical torque converter. The relationship of this power split is fixed for the life of the vehicle by the torque converter's operating characteristics. A torque converter limits power to the drivetrain when the converter input shaft is turning at engine speed and the converter output shaft is at a near zero speed. In this condition the vehicle's wheels are not turning but are transmitting torque to the ground, hereinafter this is referred to as a “stall” condition. Essentially during this condition the excess power from the engine is being converted to heat and results in wasted fuel.
Infinitely Variable Transmissions (IVT) or hydrostatic transmissions are much more efficient at this “stall” condition compared to a torque converter transmission. However, they can generate relatively too much power and very high crowd force at low ground speeds. Crowd force is defined as the amount of force with which a vehicle drives into a pile of material. Because of this, a wheel loader with an IVT or hydrostatic transmission will typically provide the hydraulic system with insufficient power. For example, a vehicle implement may try to load a pile of material and the vehicle implement may become trapped in the material because of the high crowd force. This could be due to an incorrect balance between available power for the hydraulic system and the power delivered to the drivetrain. In this condition the wheel loader's ability to move material efficiently is reduced. What is needed in the art is a system for varying and limiting the amount of power and/or torque delivered to the drivetrain.
The present invention provides a system for varying and limiting drivetrain power in an efficient manner. In accordance with one aspect of the present invention, a power management apparatus for a off-highway vehicle includes a vehicle control unit in communication with the vehicle's engine controller, transmission controller and power management actuator, wherein in response to different kinds of data or input, the vehicle control unit sends a message to the transmission controller regarding a maximum torque limit. Power management actuator includes, but is not limited to, a foot pedal.
In accordance with another aspect of the present invention, the system includes a vehicle control unit in communication with the vehicle's engine controller, transmission controller, power management actuator, implement control lever and implement velocity sensor, wherein in response to implement velocity information, the vehicle control unit sends a message to the transmission controller regarding a maximum torque limit.
The above-mentioned and other features of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention.
The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings.
Transmission controller 18 is coupled to transmission 28 and operably coupled to drivetrain 20 as well as wheel 29. Transmission controller obtains vehicle ground speed. Transmission controller 18 may broadcast vehicle ground speed data to vehicle control unit 14 over a communication network 19 such as a controller area network (CAN). In this way, vehicle control unit 14 obtains vehicle ground speed data.
In a first embodiment illustrated by
The operation of the first embodiment of power management system 10 results in the logic flow illustrated by
A second embodiment includes the same features as the first embodiment. The second embodiment further includes the following features. In the second embodiment, also illustrated by
The operation of the second embodiment results in a version of the logic flow illustrated by
Vehicle control unit 14 considers actual engine speed in order to possibly limit a maximum torque limit commanded of transmission controller 18. Calculation of the maximum torque limit reduction may involve any mathematical relation including any one or combination of the following mathematical concepts: addition, subtraction, multiplication, and/or division. For example, vehicle control unit 14 uses vehicle ground speed data and determines a maximum drivetrain torque of X. Vehicle control unit 14 then uses actual engine speed and sends a message commanding a maximum torque limit possibly limited by, for example, 10% of X due to consideration of actual engine speed.
A third embodiment includes the same features as the first embodiment. The third embodiment further includes the following features. In a third embodiment, also illustrated by
The operation of the third embodiment results in an alternative version of the logic flow illustrated by
After using power management input, vehicle control unit 14 possibly derates a maximum torque limit commanded of transmission controller 18. For example, vehicle control unit 14 uses vehicle ground speed data and determines a maximum drivetrain torque of X. Vehicle control unit 14 then uses power management input and sends a message commanding a maximum torque limit possibly limited by, for example, 10% of X due to consideration of power management input.
A fourth embodiment includes the same features as the first embodiment. The fourth embodiment further includes the following features. In the fourth embodiment, vehicle control unit 14 further includes communication with an implement control lever 21 and at least one implement velocity sensor 23. For an exemplary embodiment disclosed in
Vehicle control unit 14 includes a fourth subroutine where based on an implement velocity data an output of maximum drivetrain torque is determined. Vehicle control unit 14 considers implement velocity data before sending a message commanding a maximum torque limit if the position of implement control lever 21 is commanding movement of vehicle implement 26.
The operation of the fourth embodiment results in an alternative version of the logic flow illustrated by
A fifth embodiment includes the same features as the second and third embodiments. The operation of the fifth embodiment results in an alternative version of the logic flow illustrated by
A sixth embodiment includes the same features as the second and fourth embodiments. The operation of the sixth embodiment results in an alternative version of the logic flow illustrated by
A seventh embodiment includes the same features as the third and fourth embodiments. The operation of the seventh embodiment results in an alternative version of the logic flow illustrated by
A eighth embodiment includes the same features as the second, third and fourth embodiments. The operation of the eighth embodiment results in an alternative version of the logic flow illustrated by
Operation of power management system 10, especially during operation of vehicle implement 26, usually benefits from shifting power from drivetrain 20 to vehicle implement 26. Essentially engine 16 produces the total power for the entire system. The amount of power provided to drivetrain 20 is a portion of the total power provided by engine 16 and inversely proportional to the amount of power provided to hydraulic system 22. Similarly, the amount of power provided to hydraulic system 22 is proportional to the total power provided by engine 16 and inversely proportional to the amount of power provided to drivetrain 20. Hydraulic system 22 provides power to vehicle implement 26. Power management system 10 gives the best balance when proportioning of power supplied to drivetrain 20 and the hydraulic system 22 and therefore vehicle implement 26.
While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.
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Number | Date | Country | |
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