Patent Application
20180030687
Various exemplary embodiments relate to hydraulic control systems.
Many industrial machines, such as construction equipment, use hydraulics to control various moveable implements. The operator is provided with one or more input or control devices operably coupled to one or more hydraulic actuators, which manipulate the relative location of select components or devices of the equipment to perform various operations. For example, backhoes often have a plurality of control levers and/or foot pedals to control certain functions of a backhoe, such as a position of a boom arm, a position of a dipper arm coupled to the boom arm, and a position of a bucket coupled to a dipper arm.
According to an exemplary embodiment, an industrial task machine includes a mechanical arm and a hydraulic actuator coupled to the mechanical arm to move the arm between a first position and a second position. A valve is in fluid communication with the hydraulic actuator for supplying fluid to the hydraulic actuator. A pump is configured to discharge fluid to the valve. A load sensing system is configured to determine a load pressure value associated with the mechanical arm. A control device is configured to permit selection of a normal mode or a speed adjustment mode. A speed adjuster is configured to receive an input from the control device, modify a margin pressure value in response to selection of the speed adjustment mode, and output the modified margin pressure value. A controller is coupled to the pump, the load sensing system, and the speed adjuster. The controller is configured to receive the load pressure value from the load sensing system and the modified margin pressure value from the speed adjuster, and adjust the fluid discharge from the pump based on both the load pressure value and the modified margin pressure value.
According to another exemplary embodiment, an industrial task machine includes a frame and a plurality of movable implements coupled to the frame. Each implement individually moveable between a first position and a second position. The machine includes a plurality of hydraulic actuators, wherein at least one hydraulic actuator is coupled to each of the implements, and a plurality of valves, wherein at least one valve is coupled to each hydraulic actuator. A pump is configured to supply fluid to the valves. A load sensing system is configured to determine a load pressure value associated with each implement and to generate a signal corresponding to the highest load pressure value determined. A control device is configured to allow selection of a first speed mode, a second speed mode, or a third speed mode. A controller is coupled to the pump and to the load sensing system. The controller includes a speed adjustment portion configured to receive an input signal from the control device corresponding to the selection, to modify a margin pressure value in response to selection of either the second mode or the third mode, and to output the modified margin pressure value. The controller is further configured to receive the signal corresponding to the highest load pressure value determined and to adjust the fluid supply from the pump based on both the highest load pressure value and the modified margin pressure value.
According to another exemplary embodiment, a controller for adjusting the operating speed of a movable implement on an industrial task machine includes a speed adjustment module and a pump control module. The controller is configured to receive a speed adjustment mode signal from a control device and receive a load pressure value signal associated with the movable implement. The speed adjustment module is configured to obtain a margin pressure value and to modify the margin pressure value in response to the speed adjustment mode signal. The pump control module is configured to generate a pump pressure request based on the load pressure value and the margin pressure value and to transmit the pump pressure request to modify an output of a pump.
The aspects and features of various exemplary embodiments will be more apparent from the description of those exemplary embodiments taken with reference to the accompanying drawings, in which:
Exemplary embodiments are directed to systems and methods for adjusting the movement speed of hydraulic components in industrial machines. Industrial machines can be vehicles or stationary devices capable of performing an industrial task such as mining, agriculture, construction, manufacturing, etc. An industrial machine typically includes one or more components that cause movement or perform a task that can be generally referred to as an active component, moveable implement, or arm.
A vehicle 10 includes a number of task performing implements. For example, a loader 12 coupled to a frame 14 of vehicle 10 can lift and carry materials in a loader bucket 16 coupled to support arms 18. The support arms 18 and the loader bucket 16 can be raised or lowered relative to the frame 14 by one or more hydraulic actuators 20A and the loader bucket 16 can be moved relative to the support arms 18 by one or more hydraulic actuators 20B. A backhoe can be used to dig trenches and move material through the movement of a boom arm 22, a dipper arm 24, and a backhoe bucket 26. The backhoe bucket 26 is moveably coupled to the dipper arm 24, which is moveably coupled to the boom arm 22, which is moveably coupled to the frame 14. The boom arm 22 is rotatable relative to the frame 14 in a first and second direction 30, 32 controlled by one or more hydraulic actuators (not shown). The dipper arm 24 is rotatable relative to the boom arm 22 in a first and second direction 34, 36 controlled by one or more hydraulic actuators 38. The backhoe bucket 26 is rotatable relative to dipper arm 24 in a first and second direction 40, 42 controlled by a hydraulic actuator 44. A plurality of ground engaging or traction devices 46 are connected to the frame 14 for movement of the vehicle 10. Frame 14 can also be stabilized in a single location by one or more stabilizer arms 48. One or more control devices are positioned in a cab or operator compartment 50 to allow a user to control the movement of the implements and the vehicle 10. The operator compartment 50 is shown as an enclosed compartment, but can be open or partially enclosed.
Each of the hydraulic actuators 20, 38, 44 is illustratively shown as a hydraulic cylinder that includes a moveable piston and rod. As would be understood by one of ordinary skill in the art, the position of the rod is adjustable by the introduction and/or removal of hydraulic fluid to a respective side of the piston within the hydraulic cylinder. Further, the rate at which the rod is moved is determined by the rate hydraulic fluid is introduced or removed from a respective side of the piston.
The exemplary embodiment depicted in
The pump 102 is configured to discharge fluid to the valves 106. The rate of the fluid discharged from the pump 102 adjusts the pressure of the fluid supplied to the valves 106 and the actuators 108. The pump 102 can be capable of providing an adjustable output, for example a variable displacement pump or variable delivery pump, that is controlled based on a signal from the controller 114. A fixed displacement pump can also be used with different relief or unloading valves to effectively create a variable output. The pump 102 receives fluid, for example hydraulic oil, from the reservoir 104 and discharges fluid at the requested flow rate to create a desired system pressure.
The type of valve 106 can depend on the actuators 108 and the type of machine. Each valve 106 can be coupled to a hydraulic line to receive fluid from the pump 102 and one or more hydraulic lines to send fluid to one or more actuators 108. Although not shown, the valves 106 can be configured to receive a signal from the controller and/or one or more control devices to selectively supply fluid to the actuators 108 based on a user's commands. A basic schematic of the valves 106 is shown for clarity and one of ordinary skill in the art will understand that the valves 106 can comprise a system of one or more different types of valves, sensors, comparators, switches, regulators, and other hydraulic components including spool valves, check valves, solenoids, etc., that are controlled by various hydraulic, mechanical, or electric signals.
The actuators 108 can be similar to the actuators 20,38, 44 described above or may be any other suitable type of hydraulic actuator known to one of ordinary skill in the art.
In an exemplary embodiment, each of the actuators 108 controls the operation of a respective moveable implement. Exemplary moveable implements can include the loader bucket 16, moveable arms 18, boom arm 22, dipper arm 24, and/or backhoe bucket 26 of the vehicle 10 shown in
During use, each implement can create a variable load on the associated hydraulic actuator 108 and the hydraulic system 100 can be pressure compensated by the load sensing system 110 to account for the variable loads. The load sensing system 110 determines the load requirements of one or more of the implements and creates a load pressure value that is used to adjust the pump output. In an exemplary embodiment, a load sensing component 112 is associated with each of the valves 106 to measure the load, or pressure requirements, on the valves 106 from the actuators 108. The load sensing components 112 can be incorporated into the valves 106 or in communication therewith. For example, the load sensing component 112 can include one or more shuttle valves or isolator valves in communication with the main valves 106. The shuttle valve determines the highest pressure of two inlet pressures and sends a signal of the highest pressure to a new location. Certain systems can use a single shuttle valve associated with each actuator, while other systems can utilize a set of primary shuttle valves and a set of secondary shuttle valves. The primary shuttle valves determine the highest pressure associated with an actuator, for example extending or retracting in a double actuating cylinder, and output the higher pressure. The secondary shuttle valves are used to select the highest pressure from more than one valve 106. Accordingly, there can be one fewer secondary shuttle valve than there are primary shuttle valves. The load sensing components 112 can utilize other hydraulic, mechanical, electrical, and/or electromechanical devices and methods to determine and output the load pressure value to the controller 114.
The controller 114 can include any suitably programmed processor or computer that is capable of receiving and processing data and sending appropriate commands. The controller 114 can have multiple inputs and outputs as required. The controller 114 can be capable of operating automatically based on the inputs and also based on a manual input from the control device 116. The control device 116 can be positioned in an operator compartment 50 and can include one or more buttons, switches, levers, pedals, joystick, or other user manipulated devices.
In addition to the load pressure requirements, the controller 114 can be configured to compensate for a margin pressure. The controller 114 can instruct the pump 102 to deliver extra pressure above the required load pressure referred to as the margin pressure value. The margin pressure value can be based, for example, on the pressure loss through the system, or an estimated pressure loss. The margin pressure can also be used to assist in controlling the delivery rate of the pump to more quickly accommodate a pressure change or excess pressure demand.
The controller 114 receives the load pressure value from the load sensing system 110 and obtains the margin pressure value. These two values are then combined to achieve a pump output or flow rate. The controller 114 can obtain the margin pressure value in a number of ways. For example, the margin pressure can be: a predetermined value that is built into the controller 114, stored in memory, or received from a lookup table containing different values based on different operating parameters of the machine or vehicle; an adjustable value controlled by a user, technician, dealer, manufacturer etc.; a measured valve that fluctuates based on the use of components in the hydraulic system and/or external influences such as temperature; or any combination thereof. One of ordinary skill in the art would understand other ways of establishing the margin pressure value.
According to an exemplary embodiment, a speed adjuster 120 is capable of modifying the margin pressure value in response to an input from the control device 116 as shown in
The type of control signal and how the pump 102 is adjusted will vary dependent on the system. For example, a control signal can be sent from the controller 114 directly to the pump 102 or a pump controller, a control signal can be sent from the controller 114 through a valve in the load sensing system 110, or a control signal can be sent from the controller 114 through a load sense generation valve (not shown) and pump load sensor. The control signal can be electrical, hydraulic, mechanical, or any combination thereof. In an exemplary embodiment, an electrical signal is sent to a valve which is hydraulically connected to the pump 102.
Different operations can require different movement speeds. For example, certain operations, such as digging in close proximity to a pipe with a backhoe, require precision or fine control over the movement of the components of a backhoe. As such, a high resolution of movement rates of the respective components would be desired. In another example, such as moving dirt to a truck for removal, it is desired to provide a higher rate of movement of the components of the backhoe to reduce cycle times. As such, a lower resolution or gross resolution of movement rates would be desired.
Accordingly, the speed adjustment mode can include a slow, or precision, mode that reduces the movement speed of the implements and a fast, or productivity mode, that increases the movement speed of the implements. For example, the control device 116 has two discrete settings, a first setting corresponding to normal operation (gain=1) and a second setting corresponding to slow or precision operation (gain<1). In another example, the control device 116 has three discrete settings, a first setting corresponding to normal operation (gain=1), a second setting corresponding to precision operation (gain<1), and a third setting corresponding to fast or productivity operation (gain>1). In various exemplary embodiments, the control device 116 has a plurality of settings or has a variable gain, such as in the case of an infinitely adjustable control device 116.
In various exemplary embodiments the slow mode can be in the range of approximately 20% to approximately 100% of the speed of the normal mode, although the slow mode can be configured down to just above 0% of the normal mode if needed. In various exemplary embodiments the slow mode can be approximately 50% or approximately 55% of the speed of the normal mode. In various exemplary embodiments the fast mode can be in the range of approximately 100% to approximately 200% of the speed of the normal mode. In various exemplary embodiments the fast mode is approximately 120% or approximately 130% of the speed of the normal mode. In various exemplary embodiments the amount of speed adjustment can be selected by a user up to approximately 200% of the normal mode.
The reduction of movement speed and reduction of margin pressure can vary depending on the system. As such, the reduction in movement speed and the reduction in margin pressure are not necessarily linear, i.e. a 50% reduction of speed does not necessarily equal a 50% reduction in the margin pressure.
By altering the margin pressure, the system can effectively reduce or increase the movement speed of one or more moveable implements without the use of complex electro-hydraulic valves.
The foregoing detailed description of the certain exemplary embodiments has been provided for the purpose of explaining the general principles and practical application, thereby enabling others skilled in the art to understand the disclosure for various embodiments and with various modifications as are suited to the particular use contemplated. This description is not necessarily intended to be exhaustive or to limit the disclosure to the exemplary embodiments disclosed. Any of the embodiments and/or elements disclosed herein may be combined with one another to form various additional embodiments not specifically disclosed. Accordingly, additional embodiments are possible and are intended to be encompassed within this specification and the scope of the appended claims. The specification describes specific examples to accomplish a more general goal that may be accomplished in another way.
As used in this application, the terms “front,” “rear,” “upper,” “lower,” “upwardly,” “downwardly,” and other orientational descriptors are intended to facilitate the description of the exemplary embodiments of the present disclosure, and are not intended to limit the structure of the exemplary embodiments of the present disclosure to any particular position or orientation. Terms of degree, such as “substantially” or “approximately” are understood by those of ordinary skill to refer to reasonable ranges outside of the given value, for example, general tolerances associated with manufacturing, assembly, and use of the described embodiments.
