CN217926543U

CN217926543U - Actuator, land leveler and hydraulic cylinder

Info

Publication number: CN217926543U
Application number: CN202123048854.1U
Authority: CN
Inventors: J·S·乔治; 吴海峰
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2021-12-07
Filing date: 2021-12-07
Publication date: 2022-11-29
Anticipated expiration: 2031-12-07

Abstract

The utility model discloses an actuator, leveler and pneumatic cylinder. The actuator includes a tube having a central axially extending bore defined therein extending between a closed distal end of the tube and an open proximal end of the tube. A stem is slidably mounted within the tube and is slidably supported by the head seal assembly at the proximal end of the tube. The piston is mounted at the distal end of the rod and is retained on the rod by a piston retaining assembly attached to the distal end of the rod. A cap hole for receiving the trunnion pin is defined through the closed distal end of the tube, and a stem eye hole for receiving the stem eye pin is defined through the proximal end of the stem. When the rod and piston are fully retracted into the tube, the retracted pin-to-pin dimension is defined from the center of the cap hole to the center of the rod eye. The stroke size is defined from a first fully retracted position of the piston near the closed distal end of the tube to a second fully extended position of the piston in contact with the head seal assembly at the proximal end of the tube.

Description

Actuator, land leveler, and hydraulic cylinder

Technical Field

The present disclosure relates generally to a hydraulic cylinder for use on heavy machinery such as a grader, and more particularly, to a hydraulic cylinder having specific performance dimensions to meet the motion, structure, and load requirements of the machine.

Background

Conventional hydraulic systems on heavy machinery, such as motor graders, may include a pump that draws low-pressure fluid from a tank, pressurizes the fluid, and makes the pressurized fluid available to a number of different actuators for use in moving the actuators. The actuators may include hydraulic cylinders specifically designed to meet various motion, structure, and load requirements in order to move the various structural elements of the machine relative to one another as the machine is used to perform its assigned tasks. For example, one or more hydraulic cylinders may be specifically designed to handle hydraulic fluid pressure, motion characteristics, torsional stress, compressive stress, tensile stress, hoop stress, range of motion, and speed of motion required when operating a particular machine to perform a work task, such as leveling a road surface, or leveling a worksite of building construction. In various exemplary arrangements, the speed of each actuator may be independently controlled by selectively throttling (i.e., restricting) the flow of pressurized fluid from the pump into each actuator. For example, to move a particular actuator at high speed, the flow of fluid from the pump into the actuator is only slightly restricted (or not restricted at all). In contrast, to move the same actuator or another actuator at a low speed, the restriction on the fluid flow is increased. While suitable for many applications, the use of fluid restriction to control actuator speed may result in pressure losses that reduce the overall efficiency of the hydraulic system.

An alternative type of hydraulic system is known as a closed loop hydraulic system. Closed-loop hydraulic systems typically include a pump connected in a closed-loop manner to a single actuator or to a pair of actuators operating in series. During operation, the pump draws fluid from one chamber of the actuator(s) and discharges pressurized fluid into an opposite chamber of the same actuator(s). To move the actuator(s) at high speed, the pump discharges fluid at a faster rate. To move the actuator(s) at a low speed, the pump discharges fluid at a slower speed. Closed loop hydraulic systems are generally more efficient than conventional hydraulic systems because the speed of the actuator(s) is controlled by pump operation rather than fluid restriction. That is, the pump is controlled to discharge only as much fluid as is needed to move the actuator(s) at the desired speed, without throttling the fluid flow.

Motor graders are used primarily as finishing tools to shape the surface of a construction site or subgrade to a final shape and contour. Typically, a motor grader includes a number of manually operated controls for maneuvering the wheels of the motor grader, positioning the blade, and articulating the front frame of the motor grader. A blade is adjustably mounted to the front frame to move a relatively small amount of soil from side to side. Additionally, the articulation of the front frame is adjusted by rotating the front frame of the grader relative to the rear frame of the grader. The blade and frame may be adjusted to a number of different positions in order to create the final surface profile. Positioning the blade of a grader can be a complex and time consuming task. In particular, operations such as controlling surface elevation, angle, and depth of cut, for example, may require a significant portion of the operator's attention. Such a requirement on the operator may result in the omission of other tasks required to operate the grader.

One way to simplify operator control is to allow the operator to recall inputs stored in a memory associated with the control device. One example of such memory control is disclosed in U.S. Pat. No. 7,729,835 (' 835 patent) issued to Morris et al on 1/6/2010. Specifically, the' 835 patent discloses an excavator having a work implement and a hydraulic actuator that allows the work implement to be raised, lowered, and moved closer to or further from the body of the excavator. The excavator is equipped with a first joystick with thumbwheel control and a second joystick with function selection switches and memory control. The function selection switch allows an operator to select from a plurality of operating functions. The thumbwheel allows the operator to control the selected operational function. Memory control allows operator inputs to be stored and recalled at a later time. The inputs are stored until the memory control is disabled or a new input is stored by the memory control.

SUMMERY OF THE UTILITY MODEL

The present invention provides an actuator, grader and hydraulic cylinder that, in comparison to the hydraulic actuator disclosed in the' 835 patent, the hydraulic cylinder of the present invention is designed to have a specific performance size range determined by extensive analysis, including application of physics-based equations, finite element analysis and other computational analysis, taking into account the motion and structural stresses that can be imposed on the cylinder during use, and combining empirical data and other data intended to satisfy specific operational requirements centered on the customer, and solving one or more of the above and/or other problems in the prior art.

In one aspect, the present disclosure is directed to an actuator configured to actuate a first structural element of a grader relative to a second structural element of the grader. The actuator may comprise a tube, wherein the tube comprises a central axially extending bore defined therein, the bore extending between a closed distal end of the tube and an open proximal end of the tube, and a thickness of the tube is defined by a radial distance between an outer diameter of the tube and a bore diameter of the tube. The stem may be slidably mounted within the tube, with the stem being slidably supported by the head seal assembly at the proximal end of the tube. The piston may be mounted at the distal end of the rod, and a piston retaining assembly may be attached to the distal end of the rod and configured to retain the piston on the distal end of the rod. A trunnion cap hole may be defined through the closed distal end of the tube and configured for receiving a trunnion pin adapted to pivotally connect the distal end of the tube to a first structural member of the grader. A rod eye may be defined through the proximal end of the rod and configured to receive a rod eye pin adapted to pivotally connect the proximal end of the rod to a second structural element of the motor grader. The retracted pin-to-pin dimension from the center of the cap hole to the center of the stem eye is equal to 851.0 mm ± 2.0 mm when the stem and piston are fully retracted into the tube with the distal end of the stem located near the closed distal end of the tube; a stroke dimension from a first fully retracted position of the piston near the closed distal end of the tube to a second fully extended position of the piston in contact with the head seal assembly at the proximal end of the tube is equal to 549.0 mm ± 2.0 mm; the diameter of the rod is equal to 50.0 mm plus or minus 0.5 mm; and the diameter of the pipe hole is equal to 90.0 mm plus or minus 0.5 mm.

The diameter of the cap hole is equal to 68.0 mm +/-0.25 mm.

The diameter of the rod eye hole is equal to 68.0 mm +/-0.25 mm.

The first structural element comprises a moldboard blade of a grader.

The second structural element includes a front frame of the grader.

The first structural element comprises a dozing blade of a motor grader.

The first structural element comprises a ripper on a grader.

The second structural element includes a rear frame of the grader.

Actuation of the first structural element relative to the second structural element results in at least one of the following changes: a change in position of a moldboard blade or dozing blade of the grader relative to the ground over which the grader operates, a change in position of a moldboard blade or dozing blade relative to a front frame of the grader, a change in position of a ripper of the grader relative to the ground over which the grader operates, or a change in position of a ripper relative to a rear frame of the grader.

In another aspect, the present disclosure is directed to a grader that includes a plurality of structural elements and a plurality of hydraulic actuators, each hydraulic actuator interconnecting two of the structural elements, wherein each hydraulic actuator is configured for actuating a first structural element on the grader relative to a second structural element on the grader. Each hydraulic actuator may comprise a tube, wherein the tube comprises a central axially extending bore defined in the tube, the bore extending between a closed distal end of the tube and an open proximal end of the tube, and a thickness of the tube is defined by a radial distance between an outer diameter of the tube and a bore diameter of the tube. The stem may be slidably mounted within the tube, with the stem being slidably supported by the head seal assembly at the proximal end of the tube. The piston may be mounted at the distal end of the rod, and a piston retaining assembly may be attached to the distal end of the rod and configured to retain the piston on the distal end of the rod. A trunnion cap hole may be defined through the closed distal end of the tube and configured for receiving a trunnion pin adapted to pivotally connect the distal end of the tube to a first structural member of the grader. A rod eye may be defined through the proximal end of the rod and configured to receive a rod eye pin adapted to pivotally connect the proximal end of the rod to a second structural element of the motor grader. The retracted pin-to-pin dimension from the center of the cap hole to the center of the stem eye is equal to 851.0 mm ± 2.0 mm when the stem and piston are fully retracted into the tube with the distal end of the stem located near the closed distal end of the tube; a stroke dimension from a first fully retracted position of the piston near the closed distal end of the tube to a second fully extended position of the piston in contact with the head seal assembly at the proximal end of the tube is equal to 549.0 mm ± 2.0 mm; the diameter of the rod is equal to 50.0 mm +/-0.5 mm; and the diameter of the pipe hole is equal to 90.0 mm plus or minus 0.5 mm.

The diameter of the cap hole is equal to 68.0 mm +/-0.25 mm.

The diameter of the rod eye hole is equal to 68.0 mm +/-0.25 mm.

The first structural element includes a moldboard blade of a grader.

The second structural element includes a front frame of the grader.

The first structural element comprises a dozing blade of a grader.

The first structural element comprises a ripper of a grader.

The second structural element includes a rear frame of the grader.

In yet another aspect, the present disclosure is directed to a hydraulic cylinder configured for actuating a first structural element on a grader relative to a second structural element on the grader. The hydraulic cylinder may include a tube, wherein the tube includes a central axially extending bore defined therein, the bore extending between a closed distal end of the tube and an open proximal end of the tube, and a thickness of the tube is defined by a radial distance between an outer diameter of the tube and a bore diameter of the tube. The stem may be slidably mounted within the tube, with the stem being slidably supported by the head seal assembly at the proximal end of the tube. The piston may be mounted at the distal end of the rod, and a piston retaining assembly may be attached to the distal end of the rod and configured to retain the piston on the distal end of the rod. A trunnion cap hole may be defined through the closed distal end of the tube and configured for receiving a trunnion pin adapted to pivotally connect the distal end of the tube to a first structural member of the grader. A rod eye may be defined through the proximal end of the rod and configured to receive a rod eye pin adapted to pivotally connect the proximal end of the rod to a second structural element of the motor grader. When the rod and piston are fully retracted into the tube, with the distal end of the rod located near the closed distal end of the tube, the retracted pin-to-pin dimension from the center of the cap hole to the center of the rod eye is equal to 851.0 mm ± 2.0 mm; a stroke dimension from a first fully retracted position of the piston near the closed distal end of the tube to a second fully extended position of the piston in contact with the head seal assembly at the proximal end of the tube is equal to 549.0 mm ± 2.0 mm; the diameter of the rod is equal to 50.0 mm +/-0.5 mm; and the diameter of the pipe hole is equal to 90.0 mm plus or minus 0.5 mm.

The technical scheme of the utility model can provide improved energy use and saving. Additionally, the ability to combine fluid flows from different circuits to meet the needs of a single actuator may allow for a reduction in the number of pumps required within a hydraulic system and/or the size and capacity of these pumps. These reductions may reduce pump losses, increase overall efficiency, improve packaging of the hydraulic system, and/or reduce costs of the hydraulic system. The application of specific performance dimensions for the stroke, pin-to-pin length, rod diameter, tube bore diameter, tube outside diameter, rod eye pin diameter, and trunnion cap pin diameter of each hydraulic cylinder is based at least in part on the following results: the structural and kinematic analysis of the various structural elements of a particular grader that are required to perform certain tasks associated with the grading process also improves the efficiency and quality of the grading operation, extends the useful life of the machine, and reduces the occurrence of machine component failures or the need for repair or maintenance.

Drawings

FIGS. 1 and 2 illustrate an exemplary hydraulic cylinder that may be used to actuate one structural element on a machine, such as a grader, relative to another structural element of the machine; and

FIG. 3 illustrates an exemplary front blade lift hydraulic cylinder that may be used to control the position of a front blade on a grader.

Detailed Description

The hydraulic cylinders shown in fig. 1-3 are exemplary hydraulic cylinders that may be used as actuators on a motor grader or other heavy machinery having multiple systems and components that cooperate to accomplish a task. An exemplary motor grader may include a steerable front frame and a driven rear frame pivotally connected to the front frame. The front frame may include a pair of front wheels (or other traction devices) and support the cab. The rear frame may include a compartment for housing a power source (e.g., an engine) and associated cooling components, the power source being operably coupled to the rear wheels (or other traction devices) for primary propulsion of the grader. The rear wheels may be arranged in clusters on opposite sides of the driven rear frame. Steering of the grader may be based on front wheel steering and articulation of the front frame relative to the rear frame.

Motor graders may also include ground engaging work tools such as, for example, moldboard blades and dozing blades. Both the moldboard blade and the dozing blade may be operatively connected to and supported by the front frame. In an exemplary embodiment, the moldboard blade may be suspended from the front frame at approximately a midpoint between the front and rear wheels. The dozing blade may be supported at a forward end of the front frame (e.g., at a position forward of the front wheels relative to the normal direction of travel). In some embodiments, the rear frame may also support one or more ground engaging work tools (e.g., rippers), if desired. It is contemplated that the moldboard blade, dozing blade, and/or ripper may alternatively be connected to and supported by another portion of the grader, such as by another portion of the front frame and/or the rear frame.

Both the moldboard blade and the dozing blade may be supported via separate hydraulics. Specifically, a first hydraulic device having any number of different hydraulic actuators (e.g., hydraulic cylinders and/or hydraulic motors) may be configured to vertically displace the moldboard blade or blade tip toward and away from the front frame, to displace the moldboard blade left and right, and/or to rotate the moldboard blade about horizontal and/or vertical axes. A second hydraulic device having any number of different actuators may be configured to move the dozing blade vertically toward and away from the front frame. It is contemplated that the moldboard blade and dozer blade may be moved in other manners and/or in manners different than those described above, if desired.

A cab on a grader may house components configured to receive input from a machine operator indicative of desired machine and/or work tool movement. In particular, the cab may house one or more input devices embodied, for example, as single or multi-axis joysticks located proximate to the operator's seat. The input device may be a proportional-type controller configured to position or orient a grader by generating a position signal indicative of a desired speed and/or force in a particular direction, to articulate a front frame of a grader relative to a rear frame, or to position or orient a work tool such as a moldboard, dozer blade, and ripper. It is contemplated that different input devices may alternatively or additionally be included within the cab, such as, for example, wheels, knobs, push-pull devices, switches, pedals, and other operator input devices known in the art.

During operation of the grader, an operator may manipulate the input device from inside the cab to perform tasks that require high precision. For example, the operator may need to position the moldboard blade and/or dozing blade at a precise location and/or at a precise orientation in order to create a planned contour at the work site without colliding with another portion of the grader and/or with an obstacle at the work site. Similarly, the operator may need to move the grader itself along a precise trajectory. Also, in order for the operator to make these movements accurately and efficiently, and without damaging the grader or its surroundings, the operator may sometimes rely on position feedback from the positioning apparatus.

As each grader travels around the work site, a Global Navigation Satellite System (GNSS), local laser tracking system, or other type of positioning device or system may communicate with the positioning device to monitor the movement of the grader and/or ground engaging work tool (e.g., a moldboard blade, dozer blade, and/or ripper) and generate corresponding position signals. The position signal may be directed to an on-board controller for comparison to an electronic profile of the work site and further processing. Wherein the further processing may include determining a current ground position below the grader; a planned final contour of the work site; a current height of the moldboard blade and/or the dozing blade relative to a ground location; the current height of the moldboard blade and/or dozing blade relative to the planned final profile; and/or the current height of the dozing blade relative to the moldboard blade.

The controller may be embodied as a single microprocessor or multiple microprocessors that include a means for controlling the operation of the grader. Many commercially available microprocessors can be configured to perform the functions of the controller. The controller may include a memory, a secondary storage device, a processor, and any other components for running an application. Various other circuits may be associated with the controller such as power supply circuitry, signal conditioning circuitry, solenoid driver circuitry, and other types of circuitry.

The position feedback may be visually provided to an operator of the grader. For example, a display may be provided in the cab adjacent to the operator seat. The display may include one or more monitors (e.g., a Liquid Crystal Display (LCD), a Cathode Ray Tube (CRT), a Personal Digital Assistant (PDA), a plasma display, a touch screen, a portable handheld device, or any such display device known in the art) configured to actively and responsively display the different heights described above to an operator of the grader. A display may be connected to the controller, and the controller may execute instructions to render graphics and images associated with the operation of the grader on the display.

In some embodiments, the display may also be configured to receive input indicative of different machine operating modes. For example, the display may include one or more buttons (real or virtual), switches, knobs, dials, etc. that, when manipulated by the operator, generate corresponding signals for the controller. The controller may utilize these signals to implement, for example, a manual mode of operation, a semi-autonomous mode of operation, and/or a fully autonomous mode of operation. During the manual mode of operation, the operator of the grader may manipulate the input device to directly control the movement of the moldboard blade and the dozing blade. During the semi-autonomous mode of operation, the operator may move the input device to directly control the motion of only one work tool (e.g., only the moldboard blade). And in response to the movement of the manually controlled work tool and/or based on one or more of the relative positions described above, the controller may responsively and autonomously adjust the movement of the remaining work tool (e.g., the dozing blade or ripper). During the autonomous mode of operation, the controller may be programmed to regulate movement of all work tools via actuation of different hydraulic cylinders that are fully autonomous with inputs from different sensors.

The various hydraulic devices, input devices, controllers, and displays may together form a grader control system. In some embodiments, the control system may additionally include one or more sensors and/or one or more valves associated with the hydraulic device. The controller may be configured to utilize inputs received via the input devices, electronic maps tailored to a particular worksite, and position information to generate signals for selectively actuating the valves to cause corresponding movement of particular hydraulic actuators. The sensor may be a position sensor configured to generate a signal indicative of a position of an associated work tool (e.g., a cutting edge of a moldboard blade or dozer blade). In one embodiment, a sensor may be associated with one or more hydraulic actuators and configured to detect extension of the actuators. Based on the detected extension and the known kinematics of the grader, the controller may be configured to determine the position of the moldboard blade and/or dozing blade. In another embodiment, the sensor may be a joint-angle sensor configured to detect pivoting of one or more links within a hydraulic device of the grader. Based on the detected pivot and the known kinematics of the grader, the controller may be configured to determine the position of the moldboard blade and/or dozing blade. In yet another embodiment, the sensor may be configured to directly measure the position of the moldboard blade and/or dozing blade (e.g., relative to the front frame). In any disclosed embodiment, the signal generated by the sensor may represent an offset position relative to the position of the grader or the position of a portion of the grader. Other types of sensors may also or alternatively be used to determine the position of the cutting edge of each blade, if desired.

The valves may be configured to selectively direct pressurized fluid into and/or out of different chambers within hydraulic actuators of various hydraulic devices on the grader in response to manual inputs received via the input device and/or in response to commands generated by the controller. For example, the valve may be movable between positions where the pump supply passage is connected to a particular chamber or the tank drain passage is connected to a particular passage. As is known in the art, these connections may cause an imbalance of pressure within the associated actuator that acts to extend or retract the actuator. In addition, the hydraulic cylinder is preferably designed to have a specific size range for the stroke, a pin-to-pin length at full retraction, an aperture of a tube forming the body of the hydraulic cylinder, an outer diameter of the tube, a rod diameter extending from a piston assembly slidably supported within the tube to define a head end cavity (rodless cavity) on one side of the piston assembly and a rod end cavity (rod cavity) on the opposite side of the piston assembly, a rod end pin diameter, and a trunnion pin diameter at the head end of the cylinder, depending on the particular machine and load application in which the hydraulic cylinder will be used. Additionally, hydraulic cylinders used on heavy machinery may benefit from the particular performance dimensions disclosed herein, as well as a combination of features such as shock absorbers and head seals that improve operating characteristics, fatigue life, and performance under extreme conditions.

The power source for the grader may be embodied as an engine, such as, for example, a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other type of combustion engine known in the art. It is contemplated that the power source may alternatively embody a non-combustion power source such as a fuel cell, an electrical storage device, a tethered motor, or other source known in the art. The power source may produce a mechanical or electrical output, which may then be converted to hydraulic power to move various hydraulic cylinders that act as actuators to move structural elements or portions of the machine relative to each other or relative to the ground on which the machine is operating. An operator platform on a grader may include equipment to receive input from a machine operator indicative of a desired machine maneuver. In particular, the operator platform may include one or more operator interface devices, such as a joystick, a steering wheel, or a pedal, located proximate to the operator seat. The operator interface device may initiate movement of the grader, such as travel and/or tool movement, by generating displacement signals indicative of a desired machine maneuver. When an operator moves the interface device, the operator may affect movement of the respective machine in a desired direction at a desired speed and/or with a desired force.

As shown in fig. 1 and 2, an exemplary hydraulic cylinder may be used as an actuator to move one structural element or combination of elements on a motor grader relative to another structural element or combination of elements of the motor grader, and may include a tube (or cylinder) 322 and a piston assembly 420 disposed within the tube 322 at a distal end of the rod 332 to form a first chamber 352 and an opposing second chamber 354 on opposing sides of the piston assembly 420. One end of tube 322 is closed by a cylinder bottom or trunnion cap at distal end 342. At the opposite end, the tube 322 is closed by a head and head seal assembly 520 where the piston rod 332 exits the cylinder. The first chamber 352 on the cap end side of the piston assembly 420 may be considered a "rod end" chamber of the hydraulic cylinder, and the second chamber 354 may be considered a "head end" chamber of the hydraulic cylinder. The exemplary embodiment of the piston assembly 420 shown in fig. 2 may be disposed at the distal end of the rod 332. Piston assembly 420 may be retained on the distal end of rod 332 in a variety of ways, such as between a piston retaining assembly and a sleeve, or by a nut at the distal end of piston rod 332, as shown in fig. 2. Rod 332 may have a diameter 334, and piston assembly 420 may further include a plurality of annular seals spaced along an outer circumferential surface of piston assembly 420 that form slidable seals between piston assembly 420 and an inner circumferential surface of tube 322 as supply head end cavity 354 and rod end cavity 352, and the pressure and/or flow of hydraulic fluid released therefrom, change as rod 332 and piston assembly 420 reciprocate back and forth within tube 322.

Head end cavity 354 and rod end cavity 352 may each be selectively supplied with pressurized fluid and drained of pressurized fluid to displace piston assembly 420 within tube 322 to extend and retract rod 332 from tube 322 and change the effective length of the hydraulic cylinder. The extension and retraction of the rod 332 from the tube 322 causes one portion of the grader or a linkage structure connected to the rod 332 to move relative to another portion of the machine or a linkage structure connected to a trunnion cap fixed at the distal end 342 of the tube 322. The flow of fluid into and out of head end chamber 354 and rod end chamber 352 may be related to the translational velocity of the hydraulic cylinder, while the pressure differential between

chambers

354, 352 may be related to the force exerted by the hydraulic cylinder on the associated linkage structure of the grader.

As shown in fig. 2, the proximal end 344 of the stem 332 may pass through a head seal assembly 520, the head seal assembly 520 being attached at the end of the tube 322 through which the stem 332 passes. Head seal assembly 520 may include a plurality of axially spaced seals along an inner circumferential periphery of head seal assembly 520 that are configured to form a slidable seal with an outer circumferential surface of proximal end 344 of stem 332. A plurality of bolts may secure the head seal assembly 520 to the rod end boss, wherein a portion of the head seal assembly 520 extends at least partially radially inward from the rod end boss of the tube 322 and is configured to radially support the proximal end 344 of the stem 332 as the stem 332 and the piston 420 reciprocate relative to the tube 322. The proximal end 344 of the rod 332 may include a rod eye of diameter 252 that extends through the rod 332 perpendicular to a central axis of the rod 332 and is configured to receive a rod eye pin for pivotally attaching the proximal end 344 of the rod 332 to a first structural element of the machine 10, such as a rod eye pin that pivotally connects a rod end of a hydraulic cylinder to a first structural element of a grader. The distal end 342 of the tube 322 may similarly include a trunnion cap hole 242 having a diameter that extends through the distal end 342 of the tube 322 perpendicular to the central axis of the rod 332 and tube 322 and is configured to receive a trunnion pin that pivotally attaches the distal end 342 of the tube 322 to a second structural element of the grader, such as a trunnion pin configured to pivotally connect a head end of a hydraulic cylinder to the second structural element.

In the exemplary embodiment of hydraulic cylinders 40 shown in fig. 3, the values of the different sized determining hydraulic cylinders are based on the specific performance requirements for each hydraulic cylinder in the particular application of the grader. Specific performance dimensions include, but are not limited to: tube bore diameter 324 and outer diameter 326 of each tube 322, the thickness of each tube 322 defined by the radial distance between the tube bore diameter and the outer diameter of each tube 322, rod diameter 334 of each rod 332, diameter 252 of a rod eye extending through proximal end 344 of rod 332, diameter 242 of a trunnion cap hole extending through distal end 342 of tube 322, the outer diameter of a trunnion at distal end 342, or the inner diameter of a bearing receiving a trunnion at distal end 342, pin-to-pin length 132 between the center of the rod eye and the center of the trunnion cap hole or the center of the bearing receiving a trunnion at distal end 342 when rod 332 is fully retracted into tube 322, and stroke 222 determined by the total distance rod 332 travels from the fully retracted position to the fully extended position within tube 322. The diameter 252 of the rod eye hole, and thus the diameter of the rod eye pin configured for pivotally connecting the rod 332 of each hydraulic cylinder to a structural element of the machine 10, and the diameter 242 of the trunnion cap hole extending through the distal end 342 of the tube 322, or in some embodiments the diameter of the trunnion received within a bearing at the distal end of the tube 322, and thus the diameter of the trunnion pin or the diameter of the trunnion at the distal end of the tube configured for pivotally connecting the tube 322 of each hydraulic cylinder to another structural element of the machine 10, is determined based at least in part on the dimensions of the structural elements of the grader to which the pin is pivotally attached and the loads and structural stresses to which these elements are subjected during operation, such as shear, torsional, compressive, and tensile stresses to which these elements are subjected under certain loads during actuation of each hydraulic cylinder. The pin-to-pin dimension 132 (which may also be expressed as a pin-to-trunnion dimension when a trunnion at the distal end of the tube 322 is received within a bearing) of each hydraulic cylinder shown in fig. 1 is determined based at least in part on the dimensions, range of motion, work load, and structural interrelationships of the structural elements of the particular machine, such as the front frame and moldboard of each grader. Similarly, the stroke 222 of each hydraulic cylinder shown in FIG. 2 is determined based at least in part on the size, range of motion, workload, and structural interrelationships of the structural elements of each machine. The rod 332 and piston 420 are shown fully retracted into the tube 322 in fig. 1 and 2, with the stroke 222 being determined by the distance the piston 420 travels from this fully retracted position, where the piston bottoms out at the closed distal end 342 of the tube 322, to a fully extended position of the rod 332, where the piston 420 contacts a head seal assembly 520 connected to the proximal end of the tube 322.

The grader may include a hydraulic system having multiple circuits that drive the aforementioned fluid actuators (hydraulic cylinders) to move one portion of the grader (e.g., the moldboard) relative to another portion of the grader (e.g., the front frame). Each circuit may be similar and include a plurality of interconnected and cooperating fluid components that facilitate use and control of an associated actuator. For example, each circuit may include a pump fluidly connected to its associated actuator via a closed loop formed by a left-side channel and a right-side channel. In particular, each circuit may include a common left pump channel, a common right pump channel, a left actuator channel for each actuator, and a right actuator channel for each actuator. In a circuit with a linear actuator, the left and right actuator channels may generally be referred to as head-end and rod-end channels, respectively. Within each circuit, the respective pump may be connected to its associated actuator via a combination of left and right pump channels and left and right actuator channels.

To retract the linear actuator, the right actuator channel of a particular circuit may be filled with fluid pressurized by the pump, while the corresponding left actuator channel may be filled with fluid returning from the linear actuator. Conversely, to extend the linear actuator, the left actuator channel may be filled with fluid pressurized by the pump, while the right actuator channel may be filled with fluid exiting the linear actuator. Each pump may have a variable displacement and be controlled to draw fluid from its associated actuator and discharge fluid back to the actuator in a single direction at a specified elevated pressure. That is, the pump may include a stroke-adjusting mechanism, such as a swash plate, the position of which is hydro-mechanically adjusted, based on, inter alia, the desired speed of the actuator, to vary the output (e.g., discharge rate) of the pump. The displacement of the pump may be adjusted from a zero displacement position at which substantially no fluid is discharged from the pump to a maximum displacement position at which fluid is discharged from the pump at a maximum rate into the right pump passage. The pump may be drivably connected to the power source of the grader by, for example, a countershaft, a belt, or in other suitable manners. Alternatively, the pump may be indirectly connected to the power source via a torque converter, a gearbox, an electrical circuit, or in any other manner known in the art. It is contemplated that the pumps of the different circuits may be connected to the power source in series (e.g., via the same shaft) or in parallel (via a gear train), as desired.

A pump configured to provide pressurized hydraulic fluid to the hydraulic actuator may also optionally operate as a motor. More specifically, when the associated actuator is operating in an overspeed state, the fluid discharged from the actuator may have an elevated pressure that is higher than the output pressure of the corresponding pump. In this case, the elevated pressure of the actuator fluid returned by the pump may serve to drive the pump to rotate with or without a power source. In some cases, the pump may even be capable of transferring energy to the power source, thereby increasing the efficiency and/or capacity of the power source.

In an exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as front blade lift cylinder 40 for controlling the position of a front blade on a grader, the hydraulic cylinder may have a pin-to-pin dimension 132 equal to 851.0 mm ± 2.0 mm when fully retracted, as shown in fig. 3, with rod 332 and piston 420 bottoming out at tube 322 closed distal end 342. The stroke 222 of the exemplary hydraulic cylinder may be equal to 549.0 mm 2.0 mm. Tube bore diameter 324 may be equal to 90.0 mm 0.5 mm and tube outside diameter 326 may be equal to 105.0 mm 0.5 mm. The diameter 334 of the rod 332 may be equal to 50.0 mm ± 0.5 mm. The cap hole diameter 242 and the rod eye diameter 252 may be equal to 68.0 mm ± 0.25 mm. The disclosed dimensional ranges for a particular machine are determined from one or more of physics-based equations, finite element analysis, empirical evidence, historical evidence, and other computational analysis, in combination with consideration of factors such as kinematic interrelationships between components on the machine connected to the rod and cap ends of the cylinder, the range of motion of various structural components, the loads to which the hydraulic cylinder will be subjected during operation of the machine, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors.

Industrial applicability

The disclosed hydraulic cylinders may be adapted for use in any motor grader, wherein application of specific performance dimensions for each cylinder's stroke, pin-to-pin length, rod diameter, tube bore diameter, tube outside diameter, rod eye pin diameter, and trunnion cap pin diameter is based at least in part on the following results: structural and kinematic analysis of various structural elements of a particular machine required to perform certain tasks, such as adjusting the position of a moldboard or blade to create a desired contour along a surface to be leveled. The specific performance size of each hydraulic cylinder used on a particular machine may be determined based at least in part on: equations based on physics, as well as empirical and historical data, including fatigue analysis of structural elements under a load, the dimensions of a particular machine and the environment in which it will operate, the material from which the machine is being flattened, the relative positions of the link points that will pivotally connect the head and rod ends of each hydraulic cylinder, hydraulic system pressures, hoop, shear, compressive and tensile stresses on the various components of each hydraulic cylinder, and other mechanical design considerations.

During operation of the grader, the operator may command particular motions of one or more components of the machine relative to another component of the machine or relative to the ground. One or more signals indicative of the desired movement may be generated by an operator-manipulated interface device, or operated semi-autonomously or fully autonomously, and then transmitted to the electronic controller along with machine performance information (e.g., sensor data such as pressure data, position data, speed data, pump displacement data, and other data known in the art).

In response to the signals from the interface devices, and based on the machine performance information, the controller may generate control signals for the pump, motor, and/or valves that control the flow of hydraulic fluid to the head end cavity on one side of the piston and the rod end cavity on the opposite side of the piston of each hydraulic cylinder. In one exemplary embodiment, the controller may generate a control signal that causes the pump of the first circuit to increase its displacement and discharge fluid into the right pump passage at a greater rate than fluid discharged by the pump to the left pump passage. In addition, the controller may generate a control signal that moves and/or holds the switching valve towards and/or in one of the two flow transfer positions. After fluid from the right pump channel enters and passes through the right travel motor (e.g., or enters the head end or rod end chambers of the hydraulic cylinders), fluid from the motor or from the head end or rod end chambers on opposite sides of the piston assembly in the hydraulic cylinders may return to the pump via the left pump channel. At this point, the speed of the right travel motor, or the speed of movement of the rod and piston assembly in the hydraulic cylinder, may depend on the discharge rate of the pump and the amount of restriction (if any) provided by the switching valve to the flow of fluid through the right travel motor or into or out of the hydraulic cylinder. The motion of the right travel motor may be reversed by moving the switching valve to the other of the two flow transfer positions.

The first hydraulic cylinder may move simultaneously with the second hydraulic cylinder and/or independently of the movement of the second hydraulic cylinder. Specifically, when a first hydraulic cylinder receives fluid from the pump, one or more metering valves may move to transfer some of the fluid into a second hydraulic cylinder. At the same time, each metering valve may be moved to direct waste fluid from the hydraulic cylinder back to the pump. When the switching valve and the appropriate metering valve are fully open, the movement of the first and second hydraulic cylinders may be linked and dependent on the flow of fluid from the pump.

During some operations, the flow of fluid provided to each hydraulic cylinder from their associated pump may be insufficient to meet operator demand. During such a situation, the controller may cause the valve element(s) of one or more respective combining valves to transfer fluid from one fluid flow circuit to another fluid flow circuit, thereby increasing the flow rate of fluid available to a particular hydraulic cylinder. At this time, the fluid discharged from some of the hydraulic cylinders may be returned to the pump of the desired fluid flow circuit via the combining valve. Flow sharing between other circuits via other combining valves may be achieved in a similar manner.

Flow sharing may also be selectively achieved when the amount of fluid discharged from one actuator exceeds the rate at which the corresponding pump can effectively consume return fluid. Some of this exhaust fluid may be redirected back into the rod end chamber or the head end chamber of another hydraulic cylinder via a metering valve. This operation may be referred to as regeneration and results in increased efficiency.

The flow provided by the pump on the machine may be substantially unrestricted during many operations so that a significant amount of energy is not unnecessarily wasted during actuation. Accordingly, embodiments of the present invention may provide improved energy usage and savings. Additionally, the ability to combine fluid flows from different circuits to meet the needs of a single actuator may allow for a reduction in the number of pumps required within the hydraulic system and/or the size and capacity of these pumps. These reductions may reduce pump losses, increase overall efficiency, improve packaging of the hydraulic system, and/or reduce costs of the hydraulic system. The application of specific performance dimensions for the stroke, pin-to-pin length, rod diameter, tube bore diameter, tube outside diameter, rod eye pin diameter, and trunnion cap pin diameter of each hydraulic cylinder is based at least in part on the following results: the structural and kinematic analysis of the various structural elements of a particular grader that are required to perform certain tasks associated with the grading process also improves the efficiency and quality of the grading operation, extends the useful life of the machine, and reduces the occurrence of machine component failures or the need for repair or maintenance.

It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed hydraulic actuator and system. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed hydraulic system. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.

Claims

1. An actuator configured to actuate a first structural element on a grader relative to a second structural element on the grader, the actuator comprising:

a tube comprising a central axially extending bore defined therein and extending between a closed distal end of the tube and an open proximal end of the tube;

a stem slidably mounted within the tube, the stem being slidably supported at a proximal end of the tube by the head seal assembly;

a piston mounted at the distal end of the rod;

a piston retaining assembly attached to the distal end of the rod and configured to retain the piston on the distal end of the rod;

a cap hole defined through the closed distal end of the tube and configured for receiving a trunnion pin adapted to pivotally connect the distal end of the tube to a first structural element of the grader; and

a rod eye defined through the proximal end of the rod and configured to receive a rod eye pin adapted to pivotally connect the proximal end of the rod to a second structural element of the grader;

it is characterized in that the preparation method is characterized in that,

the retracted pin-to-pin dimension from the center of the cap hole to the center of the stem eye is equal to 851.0 mm ± 2.0 mm when the stem and piston are fully retracted into the tube with the distal end of the stem located near the closed distal end of the tube;

a stroke dimension from a first fully retracted position of the piston near the closed distal end of the tube to a second fully extended position of the piston in contact with the head seal assembly at the proximal end of the tube is equal to 549.0 mm ± 2.0 mm;

the diameter of the rod is equal to 50.0 mm +/-0.5 mm; and is

The diameter of the pipe hole is equal to 90.0 mm plus or minus 0.5 mm.

2. Actuator according to claim 1, wherein the diameter of the cap hole is equal to 68.0 mm ± 0.25 mm.

3. Actuator according to claim 1, wherein the diameter of the rod eye is equal to 68.0 mm ± 0.25 mm.

4. The actuator of claim 1, wherein the first structural member comprises a blade of a grader.

5. The actuator of claim 4, wherein the second structural element comprises a front frame of a grader.

6. The actuator of claim 1, wherein the first structural element comprises a dozing blade of a motor grader.

7. The actuator of claim 1, wherein the first structural element comprises a ripper on a grader.

8. The actuator of claim 7, wherein the second structural element comprises a rear frame of a grader.

9. The actuator of claim 1, wherein actuation of the first structural element relative to the second structural element results in at least one of the following changes: a change in position of a blade or dozing blade of a grader relative to the ground on which the grader operates, a change in position of a blade or dozing blade relative to a front frame of a grader, a change in position of a ripper of a grader relative to the ground on which the grader operates, or a change in position of a ripper relative to a rear frame of a grader.

10. A grader comprising a plurality of structural elements and a plurality of hydraulic actuators each interconnecting two of the structural elements, wherein each hydraulic actuator is configured for actuating a first structural element on the grader relative to a second structural element on the grader, each hydraulic actuator comprising:

a piston mounted at the distal end of the rod;

a rod eye defined through the proximal end of the rod and configured for receiving a rod eye pin adapted to pivotally connect the proximal end of the rod to a second structural element of the grader;

it is characterized in that the preparation method is characterized in that,

when the rod and piston are fully retracted into the tube, with the distal end of the rod located near the closed distal end of the tube, the retracted pin-to-pin dimension from the center of the cap hole to the center of the rod eye is equal to 851.0 mm ± 2.0 mm;

the diameter of the rod is equal to 50.0 mm +/-0.5 mm; and is

The diameter of the pipe hole is equal to 90.0 mm plus or minus 0.5 mm.

11. The grader of claim 10 wherein the diameter of the cap hole is equal to 68.0 mm ± 0.25 mm.

12. The grader of claim 10 wherein the diameter of the pole eye is equal to 68.0 mm ± 0.25 mm.

13. The grader of claim 10 wherein the first structural element comprises a moldboard blade of the grader.

14. The motor grader of claim 10 wherein the second structural element comprises a front frame of the motor grader.

15. The motor grader of claim 10 wherein the first structural element comprises a dozing blade of the motor grader.

16. The grader of claim 10 wherein the first structural element comprises a ripper of the grader.

17. The motor grader of claim 16 wherein the second structural element comprises a rear frame of the motor grader.

18. The grader of claim 10 wherein actuation of the first structural element relative to the second structural element results in at least one of the following changes: a change in position of a blade or dozing blade of a grader relative to the ground on which the grader operates, a change in position of a blade or dozing blade relative to a front frame of a grader, a change in position of a ripper of a grader relative to the ground on which the grader operates, or a change in position of a ripper relative to a rear frame of a grader.

19. A hydraulic cylinder configured for actuating a first structural element on a grader with respect to a second structural element on the grader, the hydraulic cylinder comprising:

a piston mounted at the distal end of the rod;

it is characterized in that the preparation method is characterized in that,

the diameter of the rod is equal to 50.0 mm +/-0.5 mm; and is provided with

The diameter of the pipe hole is equal to 90.0 mm plus or minus 0.5 mm.

20. The hydraulic cylinder of claim 19, wherein actuation of the first structural element relative to the second structural element results in at least one of the following changes: a change in position of a moldboard blade or dozing blade of the grader relative to the ground over which the grader operates, a change in position of a moldboard blade or dozing blade relative to a front frame of the grader, a change in position of a ripper of the grader relative to the ground over which the grader operates, or a change in position of a ripper relative to a rear frame of the grader.