Patent Application
20230130171
The present disclosure relates generally to grading machines, and more particularly, to hydraulic systems for motor graders.
Grading machines, such as motor graders, are typically used to cut, spread, or level materials that form a ground surface. To perform such earth sculpting tasks, grading machines include a work implement, also referred to as a blade or moldboard. The work implement may move relatively small quantities of earth from side to side, in comparison to a bulldozer or other machine that moves larger quantities of earth. Grading machines are frequently used to form a variety of final earth arrangements, which often require the work implement to be positioned in different positions and/or orientations depending on the sculpting task and/or the material being sculpted. The different work implement positions may include a blade cutting angle.
Grading machines often utilize hydraulic systems to provide functionality and control to various aspects of the machines. For example, some grading machines may utilize hydraulic brake systems, work implement systems, and/or steering systems.
A circle drive may control a position of a circle coupled to the work implement, and thus may adjust the blade cutting angle, for example. Different work implement positions may require different amounts of torque in order to adjust the work implement, especially when the work implement is engaged with material. At the beginning and/or release of a command to control the circle drive, the work implement and/or grading machine may encounter large ground forces which could back drive the motion of the circle. Further, rotating the circle and work implement while the work implement is under an excessive load can lead to slippage in the circle drive, excessive heat generation, and wear of any clutch and/or other gear train components. In some cases, during operation of the grading machine, the work implement (e.g., blade, moldboard) may impact with a heavy and/or immovable object, for example, a rock that is at least partially embedded within and protruding from the earth. The work implement may consequently transmit the forces encountered during such impacts into a driving arrangement of the machine, for example, an output shaft of a hydraulic motor that is configured to rotationally drive a circle drive gear of the grading machine.
Given the speed of the machine and its momentum when travelling on the ground surface, these forces could cause failure of one or more components associated with the driving arrangement of the machine. Hence, it would be advantageous to provide a system that mitigates a susceptibility of components in the driving arrangement from being exposed to such forces when the work implement and/or grading machine encounters resistance (e.g., imposed by the ground, heavy and/or immovable objects) in its path of travel.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and together with the description, serve to explain the principles of the disclosure.
In some embodiments, a controller 118 may be in communication with one or more features of grading machine 100. The controller 118 may receive inputs from and send outputs to, for example, user interfaces in the operator cab 116 and/or an interface remote from the grading machine 100. For example, the grading machine 100 may include electrohydraulic and/or hydro mechanical hydraulic systems, and the controller 118 may control electrical switches and/or valves to operate hydraulic cylinders, motors, actuators, and/or electrical elements. The controller 118 may include one or more controllers each associated with one or more components or systems of the grading machine 100. For example, the controller 118 may be in communication with a pump and/or directional control valves, as described in further detail herein.
The grading machine 100 may include a prime mover 120 (e.g., engine, motor) supported on the rear frame 106, for example. The prime mover 120 may supply driving power for driven components of the grading machine 100. Further, the prime mover 120 may be coupled to a pump or generator for providing hydraulic, pneumatic, or electrical power to the grading machine 100.
The grading machine 100 may include a work implement 110. In some embodiments, the work implement 110 may be a blade and/or a moldboard for helping grade soil. The work implement 110 may be used to cut, spread, level, and/or otherwise sculpt earth or other material traversed by the grading machine 100. The work implement 110 may be mounted on a linkage assembly that allows the work implement 110 to be moved to a variety of different positions and orientations relative to the front frame 104.
The grading machine 100 may include a drawbar 130 mounted to the front frame 104 via a ball and socket arrangement, for example. As shown in
The centershift cylinder 138 and the linkbar 140 may be used to shift a lateral position of the drawbar 130, and any components mounted to the drawbar 130, relative to the front frame 104 (e.g., drawbar centershift). The centershift cylinder 138 may include one end coupled to the drawbar 130 and another end pivotably coupled to the linkbar 140. In some embodiments, the linkbar 140 may include a plurality of position holes 142 for selectively positioning the linkbar 140 to the left or right to allow for further shifting of the drawbar 130 to a left or right side of the grading machine 100 by the centershift cylinder 138.
The circle 210 may be rotated by the circle drive system 200. In some embodiments, the circle drive system 200 may include a motor 250 and a gear box 260. The motor 250 may be a hydraulic motor (e.g., bidirectional) coupled to one or more hydraulic lines 252. In some embodiments, the motor 250 may be in communication with the controller 118. The motor 250 may be any motor that includes or is coupled to a rotational output shaft (e.g., gerotor type hydraulic motor, gear motor, vane motor, axial plunger motor, radial piston motor). In some embodiments, although not shown, the circle drive system 200 may include more than one motor and associated gear box (e.g., front circle drive system and rear circle drive system).
The rotational output shaft of the motor 250 may drive the gear box 260 and, in turn, rotate the circle 210. Although not shown, the gear box 260 may include an output shaft that engages with teeth on the inner portion of the circle 210 to rotate the circle 210. The gear box 260 may be directly coupled to the motor 250 or may be coupled to the motor 250 via a gear coupling (not shown). In some embodiments, the gear box 260 may be laterally adjacent to the motor 250. Moreover, the gear box 260 may include any gear arrangement (e.g., one or more epicyclic or planetary gear assemblies, spur gears, worm gears) to drive the rotation of the circle 210. In some embodiments, the gear box 260 may include one or more epicyclic or planetary gear assemblies (not shown), and a gear coupling may couple the motor 250 to the gear box 260 and the internal planetary gear assembly.
In some embodiments, the gear box 260 may also include one or more slip clutches and/or brakes, which may help to protect the motor 250 and gear arrangement in situations where the work implement 110 and/or the circle 210 encounters a heavy or severe external load while traversing the ground surface. In some embodiments, the gear box 260 may include a combining interface, which can help connect gear couplings to the other portions of the gear box 260. For example, combining interface may include an exterior with threaded holes or other coupling mechanisms to couple exterior components of the gear coupling to other portions of the gear box 260. The gear box 260 may include a housing to enclose the gearing, and a support plate mounted on the yoke plate 132 to couple the circle drive system 200 to the linkage assembly.
The rotation of the circle 210 by the circle drive system 200 may adjust a circle angle and pivot the work implement 110 relative to the drawbar 130. In some embodiments, a cutting angle may be defined as the angle of the work implement 110 relative to the front frame 104, and the cutting angle may be controlled by a combination of the position of the circle 210 and the position of the drawbar 130. Based on the effect of the circle drive system 200, the circle 210 and the work implement 110 may be rotated clockwise or counterclockwise relative to the front frame 104. In some embodiments, the circle 210 and the work implement 110 may be rotated up to about 75° clockwise and/or counterclockwise. In other embodiments, the circle 210 and the work implement 110 may be rotated 360° clockwise and/or counterclockwise. A 0° cutting angle may be created when the work implement 110 is arranged at a right angle to the front frame 104.
In some embodiments, a circle angle sensor 212 (e.g., rotary sensor, inertial measurement unit) may be positioned on the circle 210 to measure an angular rotation of the circle 210, and thus an angle of the work implement 110. For example, the circle angle sensor 212 may be mounted in a centered position on the circle 210. As another example, the circle angle sensor 212 may be mounted in an off-centered position on the circle 210, and the circle angle sensor 212 and/or other internal components of the grading machine 100 may be used to calculate the position of the circle 210 and the work implement 110 based on a compensation or correction to account for the off-centered position of the circle angle sensor 212. The circle angle sensor 212 may also help to prevent the work implement 110 from being positioned at such an angle where the work implement 110 may contact or otherwise interfere with the wheels. For example, the circle angle sensor 212 may be in communication with the controller 118, and may warn the operator and/or limit rotation of the circle 210 if a selected position would position the work implement 110 at an angle where the work implement 110 may contact wheels and/or other portions of the grading machine 100.
The grading machine 100 may include a plurality of hydraulic lines 252 to control hydraulic cylinders and/or hydraulic motors. The grading machine 100 may include a hydraulic pump (e.g., pump 330). The hydraulic pump may supply high pressure hydraulic fluid through one or more hydraulic lines 252 to one or more hydraulic cylinders and/or hydraulic motors (e.g., motor 250, bidirectional hydraulic motor 350). In some embodiments, a low pilot pressure may be provided by a hydraulic pressure reducing valve, which can receive the high pressure hydraulic fluid and supply low pilot pressure to each hydraulic cylinder and/or hydraulic motor. Additionally, each hydraulic cylinder and/or motor may include an electrical solenoid and one or more hydraulic valves. The solenoid may receive one or more signals from the controller 118 to control and position/rotation each hydraulic cylinder/motor by configuring the flow of hydraulic fluid through the valves.
The delivery of the hydraulic fluid may be controlled by the controller 118. In some embodiments, the controller 118 may control the delivery of hydraulic fluid through the hydraulic lines 252 to the motor 250 to control the position and/or orientation of the circle 210 and the work implement 110.
In some embodiments, an operator may send a command (e.g., using a joystick) to a control valve (e.g., directional control valve 310, directional control valve 410, directional control valve 412) via the controller 118 to rotate the circle 210 counterclockwise, for example. In response to the command from the controller 118, the control valve may direct the flow of hydraulic fluid from the hydraulic pump to the motor 250 via the hydraulic lines 252. In response to the pressurized flow of hydraulic fluid from the control valve through the hydraulic lines 252, the output shaft of the motor 250 may be forced to rotate, thereby driving the output of the gear box 260 to engage with the inner teeth of the circle 210 and rotating the circle 210 counterclockwise according to the operator's command.
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Additionally, in some embodiments, the pump 330 may be electronically and/or controllably connected to the controller 118, such that the operation and actuation of the pump 330 can be controlled in response to one or more signals generated by the controller 118 and electronically transmitted to, and received by, the pump 330.
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The directional control valve 310 may be in communication with the controller 118 for receiving control signals (e.g., circle rotation commands). In some embodiments, the directional control valve 310 may include a proportional valve element that may be spring biased and solenoid actuated (e.g., via a control signal from the controller 118) to move the valve element among a plurality of positions between a substantially flow blocking position (or substantially closed position) and a fully opened position. The amount of pressurized fluid directed from the pump 330 may be a function of the position of the directional control valve 310 and, thus, the corresponding amount of flow area thereof. As such, the directional control valve 310 may be configured to regulate fluid pressure in the hydraulic lines 252 associated with the pump 330. In some embodiments, the directional control valve 310 may further include first and second pilot lines upstream and downstream of the directional control valve 310, respectively, for communicating reference load pressures to the directional control valve 310.
As shown in
The directional control valve 310 may be configured to start, stop, or change the flow of the pressurized fluid and, thus, control the rotation of the bidirectional hydraulic motor 350. For example, the directional control valve 310 may be a solenoid operated, variable position, four-way, three-position valve movable between a first working position, a second position, and a neutral position. In the first working position, a first port of the bidirectional hydraulic motor 350 may be in fluid communication with the pump 330 and a second port of the bidirectional hydraulic motor 350 may be in fluid communication with a tank. In the second working position, the first port may be in fluid communication with the tank, and the second port may be in fluid communication with the pump 330. In the neutral position, the flow from the pump 330 to the bidirectional hydraulic motor 350 may be blocked. As another example, the directional control valve 310 may include an independent metering valve (IMV) system that includes plurality of independently-operated valves.
The output shaft of the bidirectional hydraulic motor 350 may include, be coupled to (e.g., via a gear coupling), and/or otherwise engage with a gear box (e.g., gear box 260) or other gearing arrangement for rotating the circle 210 of the grading machine 100. For example, the gear box 260 may include one or more components of a planetary gear assembly, and the hydraulic system 300 may include a bevel gear, gear coupling, or any other appropriate gear assembly to engage with and/or drive one or more components of the planetary gear assembly.
In some embodiments, the output shaft of the bidirectional hydraulic motor 350 may include or be affixed to a sun gear of the planetary gear assembly. The sun gear may engage with a plurality of planet gears, which in turn engage with a ring gear. Each of the planet gears may be coupled via a carrier. The ring gear may be coupled to or include a drive shaft that includes a circle engaging gear. Rotation of the ring gear, via planet gears, drives the rotation of the drive shaft and the circle engaging gear. The circle engaging gear may engage with teeth on the internal face of the circle 210 such that rotation of the circle engaging gear rotates the circle 210, and thus controls an angle of the work implement 110. Many other planetary gearing configurations in which the rotationally driven output shaft of the bidirectional hydraulic motor 350 provides the input for the planetary gear assembly are contemplated.
In other embodiments, the hydraulic system 300 may include a worm (e.g., worm screw) affixed to a free end of the output shaft of the bidirectional hydraulic motor 350, and a pinion (e.g., worm gear) may be directly coupled to one or more interior portions of the gear box 260 and may be laterally disposed to the worm. For example, a shaft may extend from the pinion and be coupled to the sun gear. Alternatively, the pinion may be directly or indirectly coupled to a carrier of the sun gear. Accordingly, in either aspect, rotation of the pinion may rotate the sun gear of the planetary gear assembly. In some embodiments, a first gear may be located at a first end of the pinion and may be disposed in selective engagement with the worm with the help of a clutch. Moreover, a second end of the pinion may be configured to bear a second gear that may be adapted to operatively drive the circle 210.
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In some embodiments, the dual counterbalance valves 340 may be configured such that the hydraulic fluid pressure threshold or valve setting (e.g., spring stiffness or winding) may be varied depending on the size of the grading machine 100 and/or the application. For example, the valve setting range of the dual counterbalance valves 340 may be from about 25,000 kPa (3,625 psi) to about 35,000 kPa (5,077 psi). In some embodiments, the actual valve setting may be about 27,500 kPa (3,989 psi). In this way, varying the valve setting may vary the hydraulic fluid pressure threshold for the hydraulic system. In some embodiments, the hydraulic fluid pressure threshold may correspond to a threshold load or torque on the motor 250, one or more slip clutches within the gear box 260, and/or the connection between the motor 250 or the gear box 260 and the circle 210. The threshold load may correspond to (e.g., be equal to or less than) a maximum torque that a component of the circle drive system 200 can withstand. The hydraulic fluid pressure threshold may be manually or automatically adjustable based on the type of grading machine 100, the type and/or temperature of material being traversed and/or graded, or other factors. For example, a user interface may allow the operator to select a severe grading application to be implemented by controller 118 by inputting the material being graded, the severity of the grading application (e.g., hard rocky material or frozen ground, soft gravel or snow), and/or the threshold load on work implement 110. In response to the operator's inputs, the user interface may display a recommended hydraulic fluid pressure threshold and/or range. Additionally or alternatively, the grading machine 100 may automatically set the hydraulic fluid pressure threshold based on the operator's inputs. Alternatively, the dual counterbalance valve assembly may not easily allow variation to the hydraulic fluid pressure threshold via the mechanical spring to prevent tampering after being set.
In some embodiments, the dual counterbalance valves 340 may be housed within a dual counterbalance valve assembly. Further, one or more components of the hydraulic system 300 may be combined into one housing or separated into multiple housings.
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The various aspects of the hydraulic systems of the present disclosure may be used in any grading/sculpting machine or other machine having one or more bidirectional hydraulic motors (e.g., motor 250). to assist an operator in positioning and orienting the work implement 110 and the circle 210. Additionally, the disclosed method of using a dual counterbalance valve assembly (e.g., dual counterbalance valves 340) within the hydraulic circuit may help prevent damage to one or more of the work implement 110, the circle 210, the motor 250, and the gear box 260 during the rotation and positioning of the work implement 110 and the circle 210.
The grading machine 100 may receive a circle rotation command to control the rotation of the circle 210 during a grading operation. For example, an operator may input a circle rotation command via a joystick or via a user interface, and the command may be transmitted to the controller 118. Alternatively, the circle rotation command may be automatically initiated or received by the controller 118 through an automated grading procedure, for example, when the grading machine 100 is moving forward and/or executing a programmed procedure.
It is noted that grading machine 100 may include any number of circle drive systems 200. The circle drive system(s) 200 may be coupled to various portions of the circle 210, and each circle drive system 200 and its components may be different sizes. Furthermore, the controller 118 may be coupled to the one or more circle drive system(s) 200. Including more than one circle drive system 200 may reduce the overall size of each circle drive system and/or the overall height. For example, the grading machine 100 may include two circle drive systems and may deliver as much or greater torque to the circle 210 with each circle drive motor being smaller than the circle drive motor (e.g., motor 250) of a grading machine 100 with a single circle drive motor. Additionally or alternatively, each gear box may be smaller or include fewer planetary gear assemblies and deliver an equal or larger torque on the circle 210 than a single circle drive system. In one aspect, each gear box may include a limit on the amount of torque that may be delivered through the gear box and/or the gear reduction of the gear box. In this aspect, including more than one circle drive system and the corresponding more than one gear box may allow for a greater torque to be delivered and/or a greater gear reduction to take place when controlling the positioning of the circle 210 and the work implement 110. Moreover, the position of the one or more circle drive systems 200 may allow for additional or larger support elements to be coupled to one or more of the drawbar 130, the circle 210, and the work implement 110 relative to the front frame 104.
Using one or more planetary gear assemblies within the circle drive system 200 may help to deliver a greater amount of torque to the teeth on the internal face of the circle 210 or other components of the work implement 110 and the circle 210. Such an increase in torque may be beneficial when adjusting a position of the work implement 110 and the circle 210 when the work implement 110 is engaged with material on a ground surface or is otherwise under the effect of external forces.
When using one or more planetary gear assemblies within the circle drive system 200 (e.g., instead of a worm and pinion), inclusion of dual counterbalance valves in the hydraulic system (e.g., hydraulic system 300) may aid in preventing the motor 250 from being driven in reverse due to external forces acting on the work implement 110. The grading machine 100 may include multiple hydraulic circuits and one or more dual counterbalance valve assemblies in order to help prevent damage to the circle drive system(s) 200 and grading machine 100. Wear or damage to the work implement 110, the circle 210, the motor 250, and the gear box 260, or another component of grading machine 100 may necessitate expensive or time-consuming repairs or otherwise affect the performance of the grading machine 100.
Using dual counterbalance valves 340 in the hydraulic circuit of a circle drive system sets a mechanical pressure threshold to help prevent damage to various components of the grading machine 100, for example, prevent slippage in the circle drive system 200, excessive heat generation, wear of a clutch or other gear train components, etc. This mechanical threshold may thus be implemented without using sensors or requiring any additional monitoring or processing to be performed by the controller 118. Advantageously, this dual counterbalance valve solution is not susceptible to software or other computing errors and may not incur any lag time in use. Further, the dual counterbalance valves 340 may lock motion of the circle 210 without having to actively physically actuate a component (e.g., brake) or disconnect any gearing connection between the circle drive motor (e.g., motor 250) and the gear box 260. In this way, the dual counterbalance valve assembly (e.g., dual counterbalance valves 340) may exist as a passive component within the hydraulic circuit.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed machine without departing from the scope of the disclosure. Other embodiments of the machine will be apparent to those skilled in the art from consideration of the specification and practice of the hydraulic systems for grading machines disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.
