Patent Publication Number: US-2018030687-A1

Title: Hydraulic speed modes for industrial machines

Description:
FIELD 
     Various exemplary embodiments relate to hydraulic control systems. 
     BACKGROUND 
     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. 
     SUMMARY 
     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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a perspective view of an exemplary industrial machine illustrated as a backhoe loader; 
         FIG. 2  is a schematic of a portion of an exemplary hydraulic system; 
         FIG. 3  is a flowchart of an exemplary speed adjuster; 
         FIG. 4  is a flow chart of an exemplary method of speed adjustment for a hydraulic system; and 
         FIG. 5  is a flow chart of an exemplary hydraulic system using a speed adjuster. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     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.  FIG. 1  shows an exemplary industrial machine illustrated as a backhoe loader vehicle  10  able to perform different operations related to digging and the movement of dirt or other materials. 
     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  20 A and the loader bucket  16  can be moved relative to the support arms  18  by one or more hydraulic actuators  20 B. 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. 
       FIG. 2  is a partial schematic of an exemplary embodiment of a hydraulic system  100  configured to supply fluid to implements in an industrial machine. A basic layout of a portion of the hydraulic system  100  is shown for clarity and one of ordinary skill in the art will understand that different hydraulic, mechanical, and electrical components can be used depending on the machine and the moveable implements. The hydraulic system  100  includes a pump  102  that receives fluid from a reservoir  104  and supplies fluid to one or more downstream components. For example, the pump  102  is in fluid communication with one or more valves  106  and each valve  106  is in fluid communication with at least one actuator  108 . A load sensing system  110  is included in or connected to the valves  106  and uses one or more load sensing components  112  to monitor the load pressure of the actuators  108 . A controller  114  is coupled to the pump  102 , the load sensing system  110 , and a control device  116  and is configured to adjust the pump output based on one or more inputs. 
     The exemplary embodiment depicted in  FIG. 2  shows three valves  106 A,  106 B,  106 C, three actuators  108 A,  108 B,  108 C, and three load sensing components  112 A,  112 B,  112 C, although any number of valves  106 , actuators  108 , and load sensing components  112  can be used. A one-to-one relationship is shown for the valves,  106 , actuators  108 , and load sensing components  112 , but more than one actuator  108  can be associated with each valve  106 , more than one valve  106  associated with each actuator  108 , and more than one load sensing component  112  can be associated with each valve  106 , as would be understood by one of ordinary skill in the art. 
     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&#39;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.  FIG. 2  shows an exemplary embodiment of three double-acting hydraulic actuators  108 A,  108 B,  108 C. Each of the double-acting actuators includes a first chamber and a second chamber and fluid is selectively delivered to the first or second chamber by the associated valve  106  to move the actuator in a corresponding direction. The actuators  108  can be in fluid communication with the reservoir  104  so that fluid leaving the actuators  108  drains to the reservoir  104 . 
     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  FIG. 1 . In one embodiment, two actuators  108  control the same implement. One example is the raising of support arms  18  which includes an actuator for each of the two support arms  18  (only one shown). In another embodiment, the actuators  108  control separate implements. One example is where the actuator  108 A controls the raising and lowering of dipper arm  24  and the actuator  108 B controls the movement of backhoe bucket  26 . The type of implements will depend on the type of industrial machine and the tasks to be performed. 
     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  FIG. 3  with the method steps described in  FIG. 4 . For example, the controller  114  receives the load pressure value (step  202 ) and the control device  116  can allow a user to select a speed adjustment mode (step  204 ). In the speed adjustment mode, the speed adjuster  120  obtains the margin pressure value (step  206 ). The margin pressure value can be obtained from the controller  114 , or it can be obtained by the speed adjuster  120  using any of the methods described above. The speed adjuster  120  modifies the margin pressure value (step  208 ) to increase or decrease the margin pressure in response to the user selection. In an exemplary embodiment a calculation is performed using the standard valve margin pressure and an increase or decrease speed request. The controller  114  combines the modified margin pressure value with the load pressure value (step  210 ) to obtain a pump output pressure as shown in  FIG. 3 . The controller  114  then produces a signal to modify the pump output (step  212 ). In an exemplary embodiment, the output is a modified pump load sense pressure value creating a modified pump output. Because the pressure generated by the pump  102  directly affects the movement speed of the hydraulic actuators, and thus the moveable implements, decreasing or increasing the margin pressure value can adjust the movement speed of all the moveable implements associated with the pump  102 . The speed adjuster  120  can be incorporated in the controller  114 , for example as a device, module, control algorithm, logic program, or other software, or the speed adjuster  120  can be a separate and independent device with a processor and memory in communication with the controller  114 , the pump  102 , or other combinations of components. 
     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 . 
       FIG. 5  shows an exemplary embodiment of a hydraulic system utilizing a speed adjuster. The system includes an actuator  302  receiving fluid from a main control valve  304 . The main control valve  304  includes a load sensing system that submits a load sense request  306  to a controller  308 . If desired, a user implements a speed mode request  310  triggering a speed mode calculation  312  based on the speed mode request  310  and the valve margin pressure  314 . The speed mode calculation  312  modifies the margin pressure  314  based on the requested speed mode and outputs the calculated valve to the controller  308 . The controller  308  combines the load sense request  306  with the calculated speed mode value  312  to create a speed mode pressure request value that is translated into a current value using a pressure vs. current lookup table  316 . The resultant current is then output to a load sense generation valve  318  that communicates with a hydraulic pump  320  to modify the flow from the pump outlet  322 . The load sense generation valve  318  can be an electro-proportional pressure control valve, for example a poppet-type hydraulic relief valve that can be infinitely adjusted across a prescribed range using a variable electric input from the controller  308 , where the pressure output is proportional to the current input. 
     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&lt;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&lt;1), and a third setting corresponding to fast or productivity operation (gain&gt;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.