Patent Application
20100021281
The present disclosure generally relates to power management and, more particularly, modifying power output of a power source as a function of a sensed torque load on the power source.
Machines, such as, for example, wheel loaders, off-highway trucks, and other heavy construction and mining machines are used to perform many tasks. To effectively perform these tasks, the machines require a power source such as a diesel engine, a gasoline engine, a natural gas engine, a turbine engine, or any other type of power source. Such machines may also include a hydraulic power unit such as a pump, motor, and/or transmission configured to transmit an input from the power source into an output to complete these tasks. For example, a hydraulic pump may be configured to convert at least a portion of the power from the engine into a flow of pressurized fluid for driving one or more fluid actuators associated with a ground engaging device or for use in an implement circuit associated with an implement.
Current power management systems do not effectively measure the amount of torque applied to a hydraulic pump and, therefore, do not recognize how much power a hydraulic pump may be consuming. Instead, current power management systems monitor and adjust based on, among other things, engine speed. As a hydraulic load of a hydraulic pump changes, the hydraulic pump requires a greater amount of power from the power source. This contributes to reduce the engine speed. When the engine speed falls below a desired engine speed, the power management system senses the speed change and reacts by increasing the supply of fuel to the engine to counter the decrease in engine speed and maintain the desired engine speed.
Such a power management system may result in detrimental engine emissions. For example, the power management system may overcompensate for a speed decrease due to an increased hydraulic load. In such instances, the over fueling of the engine may produced detrimental emissions that may exceed governmental regulations.
U.S. Pat. No. 6,817,253 (“the '253 patent”) issued to Michael D. Gandrud on Nov. 16, 2004, discloses a hydraulic power unit having torque transducers integrated into the hydraulic power unit. A system controller is communicatively coupled to the torque transducers to use the information provided by the torque transducer to monitor the performance of the hydraulic power unit and control the hydraulic power unit to limit the torque or power required by a power source. Specifically, the controller of the '253 patent is configured to control the hydraulic power unit by reducing the pressure or displacement of the hydraulic power unit in order to prevent over powering the power source such as stalling an internal combustion engine.
While the '253 patent may disclose a method of controlling a load of a hydraulic power unit to limit the power required of a power source, the '253 patent does not compensate for the over fueling of the power source based on load fluctuations of the hydraulic power unit. Specifically, the '253 patent does not disclose a method of modifying a fueling quantity supplied to the power source as a function of the sensed torque on the hydraulic power unit. Therefore, as the pressure or displacement of the hydraulic power unit of the '253 patent is adjusted, the power source may continue to produce undesirable emissions.
The disclosed methods and systems are directed to overcoming one or more of the problems set forth above and/or other problems in the art.
In one aspect, the present disclosure is directed to a method for power management in a machine. The method for power management may include sensing a parameter indicative of a torque applied to a torque consuming device rotatably driven by a power source. The method may further include modifying a quantity of fuel supplied to the power source as a function of the sensed parameter.
In another aspect, the present disclosure is directed towards a machine. The machine may include a frame, an engine mounted to the frame, and one or more load devices operatively connected to the engine. The machine may further include a controller in communication with the engine and the one or more load device. The controller may be configured to regulate a quantity of fuel supplied to the engine based on a sensed change in load on the one or more load devices.
In still another aspect, the present disclosure is directed to a method of generating a torque curve associated with a torque consuming device for use in a machine. The method may include measuring a twist angle of a shaft of the torque consuming device upon the application of a load on the torque consuming device, and measuring an actual torque applied to the shaft of the torque consuming device based on the applied load. The method may further include generating the torque curve based on a twist angle versus torque relationship and storing the torque curve on a medium associated with the torque consuming device.
Power source 14 may include an engine such as, for example, a diesel engine, a gasoline engine, a gaseous fuel powered engine such as a natural gas engine, or any other engine apparent to one skilled in the art. The power of power source 14 may be expressed as the product of the torque delivered to an output shaft 24 of power source 14 multiplied by the angular speed of output shaft 24. The angular speed of output shaft 24 may be related to engine speed. As engine speed increases, the angular speed of output shaft 24 may also increase. A decrease in engine speed may produce a corresponding decrease in the angular speed of output shaft 24.
Machine 10 may also include one or more load devices rotatably driven by power source 14. The load device may be a device that applies a load onto power source 14 such as, for example, a torque consuming device. The torque consuming device may be defined as a device that applies a torque load onto power source 14 by consuming torque produced by output shaft 24. The torque consuming device may be a pump, generator, fan, and/or any other device rotatably driven by power source 14. Specifically, a rotating pump shaft 28 of hydraulic pump 16 may be coupled to the output shaft 24 of power source 14 by way of, for example, a gear train 30. Hydraulic pump 16 may include an axial piston pump, a gear pump, a radial piston pump, or any other rotary driven device for pressurizing a flow of fluid known in the art.
Hydraulic pump 16 may be configured to transform an input from power source 14 into an output, such as movement of implement 20, ground engaging device 22, and/or any other change in state of machine 10. Specifically, hydraulic pump 16 may be configured to convert at least a portion of the power from power source 14 into a flow of pressurized fluid for an implement circuit associated with an implement 20 and/or for driving one or more drive motors associated with a ground engaging device 22. Implement 20, may include a blade, scraper, bucket, gripping device, and/or any other suitable implement. Ground engaging device 22 may include a wheel assembly, track type device, and/or any other suitable ground engaging device.
Referring now to
Barrel 32 may further include a plurality of piston openings 34 for receiving portions of a plurality of pump pistons 36. Piston openings 34 may be equally angularly spaced about a pump shaft 28 longitudinal axis 29. Piston openings 34 may be sized and oriented to allow for reciprocating movement of pump pistons 36 parallel to longitudinal axis 29 of pump shaft 28. Ends of pump pistons 36 may be seated in a plurality of piston slippers 37 slidably engaging an adjustable, non-rotating swashplate 33 to control the displacement of pump pistons 36 within the piston openings 34. In operation, pump pistons 36 rotate with pump shaft 28 and reciprocate in piston openings 34 as a function of the tilt angle of swashplate 33.
Pump shaft 28 of hydraulic pump 16 may include a first element 38 attached adjacent to a first end 40 of pump shaft 28 located proximate to the input from gear train 30 and power source 14 and on one side of swashplate 33. Pump shaft 28 of hydraulic pump 16 may include a second element 42 fixed to a second end 44 of pump shaft 28 located on the side of swashplate 33 that is opposite the input from gear train 30 and power source 14. In one embodiment, first element 38 may be a first magnet and second element 42 may be a second magnet. In an alternative embodiment, first element 38 may be a first projection and second element 42 may be a second projection. It is to be understood that first element 38 and second element 42 may be any physical configuration or feature on pump shaft 28 that may be detected by a sensor. It is also to be understood that first element 38 and second element 42 may be integral with pump shaft 28 or may be separate components that are attached to pump shaft 28, and that reference herein to the element being “attached” or “coupled” to the pump shaft 28 includes both integral and separately attached elements.
Stationary pump housing 26 may include a first sensor 46 and a second sensor 48 associated with first element 38 and second element 42, respectively, of pump shaft 28. First sensor 46 and second sensor 48 may include, for example, electrical and/or mechanical sensors or any combination thereof. First sensor 46 and second sensor 48 may be configured to detect first element 38 and second element 42, respectively, as they pass during rotation of pump shaft 28. First sensor 46 and second sensor 48 may be configured to generate a signal responsive to first element 38 and second element 42. It is contemplated that signals established by first sensor 46 and second sensor 48 may embody any signal, such as, for example, a pulse, a voltage level, a digital signal, a magnetic field, a sound or light waves, and/or other signal formats known in the art.
First sensor 46 and second sensor 48 may be configured to sense the amount of twist in pump shaft 28 as torque is applied to pump shaft 28. First sensor 46 and second sensor 48 associated with first element 38 and second element 42, respectively, may be positioned to sense the twist in pump shaft 28 between barrel 32 and the portion of pump shaft 28 coupled to the output shaft 24. It will be understood that the position of first sensor 46 and second sensor 48, as shown in
Referring back to
Controller 18 may be further configured to store data and algorithms related to twists angles, torques, and/or fueling quantities. Such data may be stored in one or more look up tables within controller 18. Alternatively or additionally, portions of the data may be derived from calculations using algorithms stored within controller 18 and based on various machine parameters. In one example, data may be stored in a torque curve for reference. The torque curve may provide torque data as a function of twist angle. In another example, data may be stored in a fuel supply adjustment curve for reference. The fuel supply adjustment curve may provide fueling adjustment data as a function of torque data. It will be apparent to one skilled in the art that a single map may be generated to provide fueling adjustment data as a function of twist angle and other inputs.
Referring to
Fuel supply adjustment curve may be additionally generated as a function of a torque applied to hydraulic pump 16. Specifically, fuel supply adjustment curve may be generated as a function of machine, power source, and pump parameters to map an adjustment in the quantity of fuel required by power source 14 to maintain engine speed when the load applied to hydraulic pump 16 changes. Fuel supply adjustment curve may be stored on controller 18.
Referring to
Having the torque applied to hydraulic pump 16, controller 18 may be further configured to detect whether the torque represents a change in load applied to hydraulic pump 28, as shown in step 245. Specifically, controller 18 may be configured to modify a fueling rate for power source 14, at step 250, based on the torque applied to hydraulic pump 16, when a change in load has occurred. Controller 18 may correlate the torque applied to hydraulic pump 16 with the fuel supply adjustment curve to determine a quantity of fuel adjustment to supply to power source 14 in order to maintain the engine speed and meet the power requirements of hydraulic pump 16. Controller 18 may continuously sense a value indicative of the torque applied to hydraulic pump 16, based on the method described above.
In an alternate embodiment, controller 18 may sum the measured torque applied to each of a plurality of hydraulic pumps 16 of machine 10. Controller 18 may then correlate the sum of the torque applied to each hydraulic pump 16 with the fuel supply adjustment curve to determine a quantity of fuel to supply to power source 14 in order to meet the collective torque consuming demands of hydraulic pumps 16 of machine 10. Controller 18 may provide a control signal for adjusting the fueling rate of power source 14 accordingly. It is contemplated that in an alternate arrangement, controller 18 may directly correlate the determined rotational time lag or the calculated twist angle with the fuel supply adjustment curve to determine a quantity of fuel to supply to power source 14.
The disclosed methods may be applicable to any powered system that includes a power source and a load device, such as, for example, a hydraulic pump configured to convert at least a portion of the power from the power source into a flow of pressurized fluid for driving one or more fluid actuators associated with a ground engaging device or an implement circuit associated with an implement.
The disclosed system and methods may have particular applicability in determining torque applied to hydraulic pump 16 for use by controller 18 in machine 10. Specifically, controller 18 may continuously monitor the torque applied to hydraulic pump 16 and modify the fueling rate to compensate for load changes and provide a precise supply of fuel to power source 14. This may allow for accurate control of power source 14 during transient loading conditions of the hydraulic pump 16, and may result in less gaseous emissions and improved fuel economy.
Alternatively or additionally, the disclosed system and methods may be used to evaluate the performance of hydraulic pump 16. In particular, the disclosed system and methods may be used to measure the torque applied to hydraulic pump 16 at a known operating condition, i.e., fixed pressure, speed, or flow rate. If the torque applied to hydraulic pump 16 changes at the known operating condition during the lifetime of hydraulic pump 16, the deviation may indicate a problem with hydraulic pump 16.
It will be apparent to those'skilled in the art that various modifications and variations can be made to the disclosed systems and methods of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being intended by the following claims.
