The present disclosure relates to an electrohydraulic system for a vehicle, and more particularly to an electrohydraulic system for a vehicle with a work implement.
Various machines or vehicles, for example those equipped with a boom and work implement, may include a several systems in communication with one another. The systems may include, for example, electrohydraulic components, engine components, transmission components, or all of the above. In some situations these components may operate differently based on the weight of a payload in the work implement.
It would be desirable for the functions of these components to be optimized based on known parameters, such as, for example, a determined payload weight in the work implement. This may present challenges, especially when attempting to measure a dynamic, or constantly changing, payload weight.
In an illustrative embodiment of the present disclosure a work machine includes: a chassis; a boom coupled to the chassis; a work implement coupled to the boom and movable relative to the chassis; a dynamic payload weighing system configured to measure a payload weight on the work implement; an electrohydraulic system controller in communication with the dynamic payload weighing system; and an electrohydraulic control valve movable in response to a signal from the electrohydraulic system controller to manipulate fluid flow through the valve. The electrohydraulic system controller is configured to move the electrohydraulic control valve through a range of valve positions based on the payload weight on the work implement. The range of valve positions includes a first valve position in which the electrohydraulic control valve facilitates fluid flow at a first flow rate and a second valve position in which the electrohydraulic control valve facilitates fluid flow fluid at a second flow rate that is less than the first flow rate.
In some embodiments, the work implement is movable through a range of implement positions bounded by a stop position of the work implement; the range of implement positions includes a weight-specific implement-position; the electrohydraulic system controller is configured to move the electrohydraulic control valve from the first valve position to the second valve position as the work implement moves between the weight-specific implement position and the stop position; and the weight-specific implement position is based on the payload weight on the work implement.
In some embodiments, the second valve position is a weight-specific valve position based on the payload weight on the work implement. In some embodiments, the stop position is a predefined position selectable by an operator of the machine. In some embodiments, the stop position is defined by a physical, absolute positional limitation the machine.
In some embodiments, the electrohydraulic system controller is configured to move the electrohydraulic control valve from the second valve-position to the first valve-position in a weight-specific amount of time; and the weight-specific amount of time is based on the payload weight on the work implement.
In some embodiments, the electrohydraulic system controller is configured to prevent the electrohydraulic control valve from moving beyond the second valve position toward the first valve position; and the second valve position is a weight-specific valve position based on the payload weight on the work implement.
In some embodiments, the work machine includes an operator-controlled device; the electrohydraulic system controller is configured to (i) receive an operator input command from the operator-controlled device and (ii) cause a movement of the work implement in response to the operator input command; the operator input command corresponds to a requested flow rate; and the movement of the work implement corresponds to an output flow rate lesser than the requested flow rate.
In some embodiments, the input flow rate relative to the output flow rate defines a metering ratio; and the electrohydraulic system controller is configured to adjust the metering ratio based on the payload weight on the work implement.
In some embodiments, the work machine includes a transmission, and a transmission controller in communication with the transmission and the electrohydraulic system controller; and the transmission controller is configured to shift between a forward gear and a reverse gear of the transmission at a gear-shift rate; and the gear-shift rate is based on the payload weight on the work implement.
In some embodiments, the dynamic payload weighing system includes: an implement position sensor, an inertial measurement unit, and a cylinder pressure measurement unit.
In another illustrative embodiment, a work machine includes: a chassis; a boom coupled to the chassis; a work implement coupled to the boom and movable relative to the chassis; a dynamic payload weighing system configured to measure the payload weight on the work implement; an electrohydraulic system controller in communication with the dynamic payload weighing system; and an electrohydraulic control valve electrically coupled to the electrohydraulic system controller and moveable to a plurality of weight-specific valve positions. The electrohydraulic control valve facilitates a different amount of fluid flow in each weight-specific valve position. Each weight-specific valve position is based on the payload weight on the work implement.
In some embodiments, the work machine includes an engine, and an engine controller in communication with the engine and the electrohydraulic system controller to communicate an amount of torque available from the engine to the electrohydraulic system controller; and the plurality of weight-specific valve positions to which to the electrohydraulic control valve is moveable is limited by the amount of torque available from the engine.
In some embodiments, the work machine includes a transmission, and a transmission controller in communication with the transmission and the electrohydraulic system controller; the transmission controller is configured to shift between forward and reverse gears of the transmission at a gear-shift rate; and the gear-shift rate is based on the payload weight on the work implement. The electrohydraulic system controller is configured to receive a signal from the transmission controller indicative of a maximum torque requestable by the electrohydraulic system controller from the engine.
In another illustrative embodiment, a method of operating a work machine includes: determining a payload weight on a work implement of the work machine using a dynamic payload weighing system; and adjusting an electrohydraulic control valve of the work implement based on the determined payload weight.
In some embodiments, adjusting an electrohydraulic control valve of the work implement based on the determined payload weight includes: determining a weight-specific implement position of the work implement based on the payload weight on the work implement; moving the work implement from the weight-specific implement position to a stop position beyond which the implement can move no further; and adjusting the electrohydraulic control valve as the work implement moves between the weight-specific implement position and the stop position.
In some embodiments, adjusting the electrohydraulic control valve as the work implement moves between the weight-specific implement position and the stop position includes: determining a weight-specific valve position of the electrohydraulic control valve based on the payload weight on the work implement; and adjusting the electrohydraulic control valve such that the electrohydraulic control valve is disposed in the weight-specific valve position when the work implement reaches the stop position.
In some embodiments, adjusting an electrohydraulic control valve of the work implement based on the determined payload weight includes: determining a weight-specific amount of adjustment time based on the payload weight on the work implement; and adjusting the electrohydraulic control valve between a first valve position and a second valve position over the weight-specific amount of adjustment time.
In some embodiments, the method includes determining an amount of torque available from an engine of the work machine; and adjusting the electrohydraulic control valve of the work implement based on the determined amount of torque available from an engine. In some embodiments, the method includes communicating the payload weight from the dynamic payload weighing system to an electrohydraulic system controller.
In some embodiments, the method includes receiving, with the electrohydraulic system controller, an operator input command from an operator-controlled device, wherein the operator input command corresponds to a requested flow rate of fluid through the electrohydraulic control valve, and calculating an output flow rate based on the requested flow rate, wherein the output flow rate is less than the requested flow rate. In some embodiments, adjusting an electrohydraulic control valve of the work implement based on the determined payload weight includes: determining an adjusted output flow rate based on the payload weight on the work implement, and adjusting the electrohydraulic control valve to facilitate fluid flow at the adjusted output flow rate.
In some embodiments, the method includes determining a maximum flow rate of fluid allowed to pass through the electrohydraulic control valve based on the payload weight on the work implement; receiving, with the electrohydraulic system controller, an operator input command from an operator-controlled device, wherein the operator input command corresponds to an requested flow rate of fluid that is greater than the determined maximum flow rate of fluid. Adjusting an electrohydraulic control valve of the work implement based on the determined payload weight includes: adjusting the electrohydraulic control valve, in response to the operator input command, to facilitate fluid flow at the maximum flow rate of fluid.
In some embodiments, adjusting an electrohydraulic control valve of the work implement based on the determined payload weight includes: determining a weight-specific gear-shift rate between forward and reverse gears of a transmission of the work machine based on the determined payload weight; and adjusting an electrohydraulic control valve based on the determining weight-specific gear-shift rate.
In some embodiments, determining a payload weight on a work implement of a work machine using a dynamic payload weighing system includes: detecting a position of the work implement, determining the inertia of the work implement, and determining the pressure in a cylinder of a boom coupled to the work implement.
The above-mentioned aspects of the present disclosure and the manner of obtaining them will become more apparent and the disclosure itself will be better understood by reference to the following description of the embodiments of the disclosure, taken in conjunction with the accompanying drawings, wherein:
Corresponding reference numerals are used to indicate corresponding parts throughout the several views.
The embodiments of the present disclosure described below are not intended to be exhaustive or to limit the disclosure to the precise forms in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may appreciate and understand the principles and practices of the present disclosure.
Referring to
The boom cylinders 62 may be coupled to an accumulator, a hydraulic source, and a tank or fluid reservoir through a hydraulic circuit. Load sense lines can be used to monitor the status of various components of the hydraulic circuit.
As shown in
In the illustrative embodiment, to achieve such control, the electrohydraulic system controller 202 may be electrically coupled to the one or more electrohydraulic control valves 204. The electrohydraulic control valves 204 are fluidly coupled to the hydraulic cylinders 62 and configured to adjust the flow rate of fluid to the hydraulic cylinders 62. In this configuration, the electrohydraulic system controller 202 is configured to move an electrohydraulic control valve 204 through a range of valve positions. In the illustrative embodiment, the range of valve positions includes at first valve position in which the electrohydraulic control valve 204 facilitates fluid flow at least a first flow rate and a second valve position in which the electrohydraulic control valve 204 facilitates fluid flow fluid at a second flow rate.
The work implement 50 is movable through ranges of positions or range of motion. For example, the implement 50 may curl and dump, as well as raise and lower. Each of these ranges of motion includes stop positions that define boundaries of the range of motion for the particular movement of the implement 50. Additionally, an operator or other user may set a predefined stop position beyond which the implement can advance no further in a particular movement. These stop positions can be pre-programmed into a memory of the machine 10 for any number of reasons including: identification of a desired height or dump-angle for a commonly repeated action of the implement, a height-limit or curl-limit associated with a known implement type, etc. In some applications, it may be desirable to automatically reduce the flow rate of fluid to the hydraulic cylinders 62 as the implement 50 approaches a stop position. Such an automatic reduction in flow rate may be referred to as “cushioning”. The cushioning feature of the work machine 10 may improve ride comfort, safety, and operating efficiency of the machine 10.
As suggested by
As the implement 50 moves through its range of positions, the electrohydraulic system controller 202 is configured to adjust the fluid flow rate through the electrohydraulic control valves 204 at a predetermined position of the implement 50. In other words, as the implement 50 moves toward a stop position, the flow rate is reduced beginning when the implement 50 reaches the predetermined position. It should be appreciated that the predetermined position is based on the weight on the implement 50. The predetermined position may be referred to as a weight-specific position. When the implement 50 reaches the weight-specific position, the electrohydraulic system controller 202 is configured to move the electrohydraulic control valve 204 from a first valve position associated with a first flow rate to a second valve position associated with a second, lesser flow rate.
If the dynamic payload weighing system 200 indicates a greater load on the implement 50, the electrohydraulic system controller 202 will request a reduction in flow at a first position of the implement 50 relative to a stop position; comparatively, if the dynamic payload weighing system 200 indicates a lesser load on the implement 50, the electrohydraulic system controller 202 will request a reduction in flow beginning at a second position of the implement, where the second position of implement 50 is a greater distance away from the stop position than is the first position of the implement 50. This function allows for optimized initiation of the cushioning feature of the work machine 10 based on the payload weight on the implement 50.
It may be desirable to adjust fluid flow at greater or lesser adjustment rates based on the weight on the implement 50. For example, in some embodiments, an operator of the work machine may request a near-instantaneous increase or decrease in the fluid flow rate; however, the work machine 10 may automatically adjust the fluid flow rate over a longer period of time rather than nearly instantaneously. This delay in flow rate adjustment may be introduced to improve operator comfort, safety, or machine efficiency. The period of time over which the adjustment in flow rate occurs is based on the weight on the implement 50, and may be referred to as a weight-specific amount of time. For example, if the dynamic payload weighing system 200 indicates a greater load on the implement 50, the electrohydraulic system controller 202 will adjust the position of the valve 204 more slowly (i.e. the weight specific amount of time will be greater); comparatively, if the dynamic payload weighing system 200 indicates a lesser load on the implement 50, the electrohydraulic system controller 202 will adjust the position of the valve 204 more quickly (i.e. the weight specific amount of time will be lesser). This function allows for optimization of the flow rate adjustment time for the work machine 10 based on the payload weight on the implement 50.
In some embodiments, the electrohydraulic system controller 202 is capable of controlling the maximum flow rate for the implement 50. The maximum flow rate may be based on the weight on the implement 50. It should be appreciated that in each embodiment, various implements 50 may be used with the work machine 10, and each implement 50 may have a different weight. Thus, when the phrase “payload weight on the implement” or “weight on the implement” are used, the terms are used to describe the total weight on the implement 50 inclusive of the weight of the implement 50 itself.
In the illustrative embodiment, a maximum flow rate may be determined. The maximum flow rate may be associated with a weight-specific position of the electrohydraulic control valve 204. As such, the electrohydraulic system controller 202 is configured to prevent the electrohydraulic control valve 204 from moving beyond the weight-specific valve position. As described above, the weight-specific valve position is based on the payload weight on the implement 50. This function allows for optimization of the maximum flow rate-limit for the work machine 10 based on the payload weight on the implement 50.
It may be desirable to adjust the difference between an operator-requested (or input) flow rate versus an actual (or output) flow rate based on the weight on the implement 50. For example, in some embodiments, an operator of the work machine 10 may request a first fluid flow rate; however, the work machine 10 may automatically output a second, lesser fluid flow rate. This reduction in actual flow rate may be introduced to improve operator comfort, safety, or machine efficiency. The value of the difference between the input fluid flow rate and the output fluid flow rate may change with the magnitude of the fluid flow rate requested by the operator. This changing value of the difference describe above may be graphical represented and referred to as a metering curve. The metering curve may be adjusted based on the weight on the implement 50.
As shown in
As shown in
As shown in
In some embodiments, a power management system may be included with or as a part of the electrohydraulic system controller 202. The power management system may be configured to determine an amount of torque required from the engine 212 to support various components of the electrohydraulic circuit. However, in some work machines, especially those without a dynamic payload weighing system 200, the weight on the implement is always assumed to be a maximum value for purposes of determining the amount of excess torque available from the engine. Thus, the power management system of such machines cannot determine the amount of torque required to support various components of the electrohydraulic circuit as accurately as may be desired.
In the embodiment described here, the actual weight on the implement is determined by the dynamic payload weighing system 200, and therefore, the amount of torque required by the implement 50 can be measured constantly and more accurately. In such an embodiment, if the dynamic payload weighing system 200 indicates a lesser load on the implement 50, the electrohydraulic system controller 202 can initiate greater flows rate in the electrohydraulic circuit than if the dynamic payload weighing system 200 were to indicate a greater load on the implement 50. In this configuration, the electrohydraulic system controller 202 is configured to adjust the electrohydraulic control valves 204 that are coupled to the other hydraulic outputs 216 based on the weight on the implement 50. This function allows for optimization of flow rates associated with the other hydraulic outputs 216 of the work machine 10 based on the payload weight on the implement 50.
While embodiments incorporating the principles of the present disclosure have been described hereinabove, the present disclosure is not limited to the described embodiments. Instead, this application is intended to cover any variations, uses, or adaptations of the disclosure 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 disclosure pertains and which fall within the limits of the appended claims.
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