CN212717453U

CN212717453U - Actuator and machine

Info

Publication number: CN212717453U
Application number: CN202020266541.XU
Authority: CN
Inventors: P·K·布赖恩; S·贾斯汀; M·正之; K·康博
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2020-03-06
Filing date: 2020-03-06
Publication date: 2021-03-16
Anticipated expiration: 2030-03-06

Abstract

An actuator and machine, the hydraulic cylinder of the actuator including a tube having 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. The stem is slidably mounted within the tube and is slidably supported at the proximal end of the tube by the head seal assembly. The piston is mounted on 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 trunnion cap hole for receiving a trunnion pin is defined through the closed distal end of the tube, and a rod eye hole for receiving a rod eye pin is defined through the proximal end of the rod. When the rod and piston are fully retracted into the tube, the retracted pin-to-pin dimension is defined from the center of the trunnion cover hole to the center of the rod eye hole. The stroke is sized to be from a first fully retracted position of the piston adjacent 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 and machine

Technical Field

The present disclosure relates generally to a hydraulic cylinder in an actuator for use on a heavy machine, and more particularly to a hydraulic cylinder having specific performance dimensions that meet the kinematic, structural, and load requirements of the machine.

Background

Conventional hydraulic systems on heavy machinery such as excavators, motor graders, front end loaders, and dozers may include a pump that draws low pressure fluid from a tank, pressurizes the fluid, and makes the pressurized fluid available to a plurality of different actuators for moving the actuators. The actuators may include hydraulic cylinders specifically designed to meet various kinematic, structural, and load requirements for moving various structural elements of the machine relative to one another while using the machine to perform its designated tasks. For example, one or more hydraulic cylinders may be specifically designed to handle hydraulic fluid pressure, motion characteristics, torsional stresses, compressive stresses, tensile stresses, hoop stresses, range of motion, and speed of motion required when operating a particular machine to perform work tasks such as digging, moving soil, lifting heavy loads, and carrying heavy loads. 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 to each actuator. For example, to move a particular actuator at high speed, fluid flow from the pump into the actuator is limited only by a small amount (or not at all). Conversely, to move the same or another actuator at a low speed, the restriction to fluid flow is increased. While the use of fluid restriction to control actuator speed is sufficient for many applications, this can result in pressure losses, which in turn reduces the overall efficiency of the hydraulic system.

Another 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 and discharges pressurized fluid to an opposite chamber of the same actuator. For example, when the rod of the hydraulic cylinder is retracted, hydraulic fluid may be pumped into the rod end chamber of the hydraulic cylinder and drained from the head end chamber on the opposite side of the piston connected to the rod in the hydraulic cylinder, and when the rod is extended, hydraulic fluid may be pumped into the head end chamber and drained from the rod end chamber. To move the actuator at a higher speed, the pump discharges fluid at a faster rate. To move the actuator at a slower speed, the pump discharges the fluid at a slower speed. Closed loop hydraulic systems are generally more efficient than conventional hydraulic systems because the speed of the actuator is controlled by pump operation rather than fluid restriction. That is, the pump is controlled to discharge only the amount of fluid required to move the actuator at the desired speed, and no throttling of the fluid flow is required.

An exemplary closed-loop hydraulic system for use with one or more hydraulic cylinders is disclosed in us patent 4,369,625 to Izumi et al (the' 625 patent), published 25/1/1983. In the' 625 patent, a multiple actuator, flowmeter-less hydraulic system having flow combining functionality is described. The hydraulic system comprises a swing rod loop, a cantilever loop, a suspender loop, a bucket loop, a left walking loop and a right walking loop. Each of the swing link circuit, the boom circuit, and the boom circuit has a pump connected to a dedicated hydraulic cylinder in a closed-loop manner. In addition, a first combination valve is connected between the swing link circuit and the boom circuit, a second combination valve is connected between the boom circuit and the boom circuit, and a third combination valve is connected between the bucket circuit and the boom circuit. The left walking loop and the right walking loop are respectively connected with the pumps of the bucket loop and the cantilever loop in parallel. In this configuration, any one cylinder may receive pressurized fluid from more than one pump such that its speed is not limited by the capacity of a single pump.

Despite improvements to existing closed-loop hydraulic systems, the closed-loop hydraulic system of the' 625 patent is still not optimal. In particular, the connection circuits of the system may be performed only in order. In addition, it may be difficult to control the speed and force of the various actuators.

Disclosure of Invention

The utility model provides an actuator and machine can solve a plurality of structural stress consideration in the unreasonable design brought of actuator structure size design that prior art exists not comprehensive, influence operating characteristic, fatigue life and hydraulic system's the overall inefficiency scheduling problem.

An actuator configured for actuating a first structural element on a machine relative to a second structural element on the machine, the actuator comprising:

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

a piston mounted at a 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 between the piston retaining assembly and a bushing mounted on a reduced diameter portion of the distal end of the rod;

a trunnion cover hole defined through the closed distal end of the tube and configured to receive a trunnion pin adapted to pivotally connect the distal end of the tube to the first structural element of the machine; and

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

A retracted pin-to-pin center distance dimension from a center of the trunnion cover hole to a center of the rod eye hole is equal to 2827mm ± 2.5mm when the rod and piston are fully retracted into the tube and the distal end of the rod is positioned adjacent the closed distal end of the tube;

a stroke dimension from a first fully retracted position of the piston adjacent 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 1967mm ± 1.5 mm;

the diameter of the rod eye hole is equal to 150mm +/-0.5 mm; and

the diameter of the trunnion cover hole is equal to 150mm +/-0.5 mm.

The first structural element comprises a body of an excavator.

The second structural element comprises a boom of the excavator.

Further comprising a damping assembly disposed at the closed distal end of the tube, adjacent the distal end of the rod when the rod is fully retracted into the tube.

The damping assembly projects axially from the closed distal end radially centrally located portion of the tube.

The damping assembly is configured to be received within a mating blind hole formed in the distal end of the rod when the rod is fully retracted into the tube.

Further comprising a damping assembly retained within a blind bore in the distal end of the rod, the damping assembly configured to enter a radially centrally located axial bore in the closed distal end of the tube when the rod is fully retracted into the tube.

Further comprising an axially oriented relief aperture extending into the closed distal end of the tube, the relief aperture extending parallel to and offset from a central axis of the tube, penetrating into the closed distal end of the tube, and intersecting a radially oriented pressure relief aperture extending between a pressure relief compartment defined in the distal end of the tube and an outer perimeter of the tube.

The head seal assembly is threadably connected to and disposed on a rod end boss at the proximal end of the tube.

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

a piston mounted at a distal end of the rod;

the diameter of the rod eye hole is equal to 150mm +/-0.5 mm; and

the diameter of the trunnion cover hole is equal to 150mm +/-0.5 mm.

In one aspect, the present disclosure is directed to an actuator configured to actuate a first structural element of a machine relative to a second structural element of the machine. The actuator may include a tube including 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, wherein the stem is slidably supported at the proximal end of the tube by a head seal assembly. 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, between the piston retaining assembly and a bushing mounted on the reduced diameter portion of the distal end of the rod. A trunnion cover bore 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 element of the machine. 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 machine.

In another aspect, the present disclosure is directed to a machine including a plurality of structural elements and a plurality of hydraulic actuators, each hydraulic actuator interconnecting two structural elements, wherein each hydraulic actuator is configured to actuate a first structural element on the machine relative to a second structural element on the machine. Each hydraulic actuator may include a tube including 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, wherein the stem is slidably supported at the proximal end of the tube by a head seal assembly. 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, between the piston retaining assembly and a bushing mounted on the reduced diameter portion of the distal end of the rod. A trunnion cover bore 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 element of the machine. 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 machine.

In yet another aspect, the present disclosure is directed to a hydraulic cylinder configured for actuating a first structural element on a machine relative to a second structural element on the machine. The hydraulic cylinder may include a tube, wherein the tube includes a central axially extending bore defined therein that extends between a closed distal end of the tube and an open proximal end of the tube. A stem is slidably mounted within the tube, wherein the stem is slidably supported at the proximal end of the tube by a head seal assembly. 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, between the piston retaining assembly and a bushing mounted on the reduced diameter portion of the distal end of the rod. A trunnion cover bore 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 element of the machine. 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 machine.

It can be seen that the hydraulic cylinder is preferably designed to have a specific range of stroke sizes, length of pin-to-pin center distance at full retraction, diameter of the rod end pin, and diameter of the trunnion pin at the cylinder head end, depending on the particular machine and load application in which the hydraulic cylinder will be used. With a specifically sized actuator, a hydraulic cylinder for use on a heavy machine may benefit from the specific performance dimensions disclosed herein in combination with features such as damping devices and head seals that improve operating characteristics, fatigue life, and performance under extreme conditions.

The hydraulic cylinder of the present invention is designed to have a range of specific performance dimensions determined by extensive analysis including the application of physics-based equations, finite element analysis, and other computational analysis that takes into account the kinematics and structural stresses that will be imposed on the hydraulic cylinder during use, combined with empirical data and other customer-centric data intended to meet specific operational requirements and address one or more of the above-mentioned problems and/or other problems of the prior art.

In the disclosed solution, the flow provided by the various pumps may be substantially unrestricted during many operating conditions, so that a large amount of energy is not unnecessarily wasted during the actuation process. Accordingly, embodiments of the present invention may provide improved energy usage and savings. Furthermore, the ability to combine fluid flows from different circuits to meet the needs of individual actuators 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, improve overall efficiency, improve packaging of the hydraulic system, and/or reduce costs of the hydraulic system. All of the above-discussed considerations of sharing pressurized hydraulic fluid between certain hydraulic circuits and cylinders of the machine, as well as considerations of regeneration when returning energy to the hydraulic system, may also take into account computational analysis used in determining the performance dimensions of each cylinder, such as stroke size, pin-to-pin center distance dimensions, trunnion cap hole and trunnion pin diameters, and rod eye pin diameters.

Drawings

FIG. 1 is a diagrammatic illustration of an exemplary disclosed machine;

FIG. 2 is a schematic illustration of an exemplary disclosed hydraulic cylinder that may be used as an actuator on the machine of FIG. 1;

FIG. 3 is a cross-sectional view of the exemplary disclosed hydraulic cylinder of FIG. 2;

FIG. 4 is an enlarged view of a portion I of the hydraulic cylinder of FIG. 3, showing the piston retaining assembly at the first end of the piston rod of the hydraulic cylinder;

FIG. 5 is an enlarged view of a portion II of the hydraulic cylinder of FIG. 3, showing the head seal arrangement at the piston rod end of the hydraulic cylinder.

Detailed Description

FIG. 1 illustrates an exemplary machine 10 having multiple systems and components that cooperate to accomplish a task. Machine 10 may embody a fixed or mobile machine that performs some type of operation associated with an industry such as mining, construction, farming, transportation, or another industry known in the art. For example, machine 10 may be an earth-moving machine such as an excavator (shown in FIG. 1), a dozer, a front end loader, a backhoe, a motor grader, a dump truck, or any other earth-moving or other heavy-duty machine. Machine 10 may include an implement system 12 configured to move a work tool 14, a drive system 16 for propelling machine 10, a power source 18 that provides power to implement system 12 and drive system 16, and an operator station 20 configured to manually control implement system 12, drive system 16, and/or power source 18.

Implement system 12 may include a linkage structure acted on by fluid actuators to move work tool 14. Specifically, implement system 12 may include a boom 22 that is vertically pivotable about a horizontal axis (not shown) relative to a work surface 24 via a pair of adjacent, double-acting, hydraulic cylinders 26 (only one shown in fig. 1). Implement system 12 may also include a boom 28, with boom 28 being vertically pivoted about a horizontal axis 30 by a single, double-acting, hydraulic cylinder 32. Implement system 12 may also include a single, double-acting, hydraulic cylinder 34, where hydraulic cylinder 34 may be operably connected between boom 28 and work tool 14 to vertically pivot work tool 14 about a horizontal pivot axis 36. In the disclosed embodiment, hydraulic cylinder 34 is connected to a portion of boom 28 at a head end 34A and to work tool 14 at an opposite rod end 34B via a power link 37. Boom 22 may be pivotally connected to a body 38 of machine 10. Body 38 may be pivotally connected to chassis 39 and may be moved about a vertical axis 41 by a hydraulic swing motor 43. Boom 28 may pivotally connect boom 22 to work tool 14 via axes 30 and 36. It is contemplated that a different number and/or configuration of actuators may alternatively be included within implement system 12, in the same or a different manner than described above, if desired.

Many different work tools 14 may be attached to a single machine 10 and operator controllable. Work tool 14 may include any device used to perform a particular task such as, for example, a bucket, a fork arrangement, a blade, a shovel, a ripper, a dump bed, a broom, a snow blower, a propulsion device, a cutting device, a gripping device, or any other task-performing device known in the art. Although work tool 14 is connected in the embodiment of fig. 1 to pivot in a vertical direction and swing in a horizontal direction with respect to body 38 of machine 10, work tool 14 may alternatively or additionally rotate, slide, open and close, or move in any other manner known in the art. Further, while the exemplary embodiment in FIG. 1 shows a hydraulic cylinder configured for actuating a structural element of an excavator, including a boom, and a bucket, one of ordinary skill in the art will recognize that embodiments of the disclosed hydraulic cylinder may be interconnected between other structural elements on different machines to actuate any structural element of a machine relative to another structural element of the machine while performing a particular task for which the machine is designed.

Drive system 16 may include one or more traction devices that are powered to propel machine 10. In the disclosed example, drive system 16 includes a left track 40L located on one side of machine 10 and a right track 40R located on an opposite side of machine 10. Left track 40L may be driven by a left travel motor 42L, while right track 40R may be driven by a right travel motor 42R. It is contemplated that drive system 16 may alternatively include traction devices other than tracks, such as rollers, belts, or other known traction devices. Machine 10 may steer by creating a speed and/or rotational direction difference between left and

right travel motors

42L, 42R, while straight travel may be facilitated by creating a substantially equal output speed and rotational direction from left and

right travel motors

42L, 42R.

Power source 18 may embody an engine such as, for example, a diesel engine, a gasoline engine, a gaseous fuel-powered engine, or any other type of internal combustion engine known in the art. It is contemplated that power source 18 may alternatively embody a non-combustion power source such as, for example, a fuel cell, a power storage device, a tethered motor, or another power source known in the art. Power source 18 may produce a machine or electrical output that may then be converted into hydraulic power for moving

hydraulic cylinders

26, 32, 34 and left, right, and

swing motors

42L, 43.

Operator station 20 may include devices to receive input from a machine operator indicative of a desired machine maneuver. Specifically, operator station 20 may include one or more operator interface devices 46, such as a joystick, a steering wheel, or pedals, located near an operator seat (not shown). Operator interface device 46 may initiate movement of machine 10, such as walking and/or tool movement, by generating displacement signals indicative of a desired machine maneuver. As the operator moves the interface device 46, the operator may operate the respective machine movement in a desired direction at a desired speed and/or a desired force.

As shown in fig. 2 and 3,

hydraulic cylinders

26, 32, 34 may each include a tube 322 and a piston 420 disposed within tube 322 to form a first chamber 352 and an opposing second chamber 354. First chamber 352 may be considered a head end chamber, and second chamber 354 may be considered a rod end chamber of

hydraulic cylinders

26, 32, 34. The tube 322 may include a central axially extending bore defined in the tube extending between the closed distal end 342 of the tube 322 and the open proximal end of the tube. The exemplary embodiment of piston 420 and piston retaining assembly 430 shown in fig. 3 and 4 may be disposed at the distal end of rod 332. Piston 420 may be retained on the distal end of rod 332 between piston retaining assembly 430 and bushing 410, as shown in fig. 4. Bushing 410 may abut a reduced diameter shoulder of the distal end of rod 332. In alternative embodiments, piston retaining assembly 430 may be threadably engaged or press-fit onto the distal end of rod 332, and bushing 410 may be eliminated or replaced with a resilient shock absorbing member configured to help reduce vibrations and absorb any impact due to piston 420 striking closed distal end 342 of tube 322 at the end of each stroke. Piston 420 may also include a plurality of annular seals 422 spaced along the outer periphery of piston 420 and forming a slidable seal between piston 420 and the inner peripheral surface of tube 322 as rod 332 and piston 420 reciprocate back and forth within tube 322 as a function of the pressure and/or flow rate of hydraulic fluid supplied to and released from head end chamber 352 and rod end chamber 354.

In some exemplary embodiments, a damping assembly 440 may be provided at the closed distal end 342 of the tube 322, adjacent the distal end of the piston rod 332 at the end of stroke stop of the piston rod 332, as shown in fig. 3 and 4. Additionally, a piston retaining assembly 430 may be threadably attached or otherwise secured to the distal end of the piston rod 332, abutting one axial end of the piston 420, and received within a radially inwardly extending rib 325, the rib 325 being formed near the closed distal end 342 of the tube 322 at the end of each stroke. As piston 420 and piston retaining assembly 430 approach closed distal end 342 of tube 322 at the end of each stroke, hydraulic fluid trapped in head end chamber 352 may be forced through the gap between rib 325 and the outer circumferential surface of piston retaining assembly 430, contributing to a damping effect that slows the travel of piston rod 332 and piston 420 prior to impact with closed distal end 342 of tube 322. Damping assembly 440 may also be configured with an internal passage designed to restrict the flow of hydraulic fluid escaping from head end chamber 352 at the end of each stroke of piston 420 and rod 332.

Damping assembly 440 may protrude axially from a radially centrally located portion of closed distal end 342 of tube 322, and may be configured to be received within a mating blind hole formed in the distal end of rod 332 at the end of stroke of rod 332. Damping assembly 440 may enter a blind hole in the distal end of rod 332 each time rod 332, piston retaining assembly 430, and piston 420 approach the closed distal end 342 of tube 322. In an alternative embodiment, the damping assembly 440 may be retained within a blind bore in the distal end of the rod 332 with one or more annular seals 460 fitted between an outer peripheral surface of the damping assembly 440 and an inner peripheral surface of the blind bore in the distal end of the rod 332. Damping assembly 440 may be configured to enter a radially centrally located axial bore in closed distal end 342 of tube 322 at the end of each stroke. An axially oriented relief aperture 451 may also be formed in the closed distal end 342 of the tube 322, extending parallel to and offset from the central axis of the tube 322 and the stem 332, wherein the axially oriented relief aperture 451 penetrates the closed distal end 342 of the tube 322 and intersects a radially oriented relief aperture 450 extending between a pressure relief compartment 452 formed in the distal end 342 of the tube 322 and the outer perimeter of the tube 322. When piston 420, piston retaining assembly 430, and damping assembly 440 approach closed distal end 342 of tube 322 at the end of stroke dead center (or when piston 420 and piston retaining assembly 430 approach damping assembly 440 protruding from distal end 342), damping assembly 440 may be configured to enter a blind hole in the distal end of rod 332. Fluid in head end chamber 352 may be forced through axially oriented release apertures 451 into pressure release chamber 452 and out of radially oriented release apertures 450. The damping assembly 440 may also include a central axially oriented release bore 446 and a plurality of radially extending and axially spaced

passages

442 and 444 that penetrate from the central axially oriented release bore 446 to the outer periphery of the damping assembly 440. The central axially-oriented relief bore 446 and the radially-extending

passages

442 and 444 in the damping assembly 440 may be configured to facilitate adjustment of the amount and flow rate of hydraulic fluid that may escape from the head end chamber 352 as the piston 420 and piston retaining assembly 430 near the closed distal end 342 of the tube 322 at the dead center portion of the stroke, thereby serving to adjust the damping effect and prevent the rod 332, the piston 420, and the piston retaining assembly 430 from strongly impacting the bottom of the closed distal end 342 of the tube 322.

Each of head end chamber 352 and rod end chamber 354 may selectively supply and exhaust pressurized fluid to move piston 420 within tube 322 to change the effective length of

hydraulic cylinders

26, 32, 34 and move work tool 14 (see fig. 1), or to otherwise move one structural component of machine 10 to which one of proximal end 344 of piston rod 332 or distal end 342 of tube 322 is pivotally connected relative to another structural component of machine 10. The flow rate of fluid into head end chamber 352 and fluid out of rod end chamber 354 may be related to the translational velocity of

hydraulic cylinders

26, 32, 34, and the pressure differential between head end chamber 352 and rod end 354 may be related to the force exerted by

hydraulic cylinders

26, 32, 34 on the associated linkage of implement system 12.

As shown in fig. 3 and 5, the proximal end 344 of the stem 332 may pass through a head seal assembly 520, the head seal assembly 520 being threaded or otherwise attached to the stem end boss 324 at the proximal end of the tube 322. The head seal assembly 520 may include a plurality of axially spaced seals 522 along the inner circumferential perimeter of the head seal assembly 520 that are configured to form a slidable seal with the outer perimeter of the proximal end 344 of the stem 332. A plurality of bolts 327 may secure the head seal assembly 520 to the rod end boss 324, wherein a portion of the head seal assembly 520 extends at least partially radially inward from the rod end boss 324 of the tube 322 and is configured to radially support the proximal end 344 of the rod 332 as the rod 332 and piston 420 reciprocate relative to the tube 322. Proximal end 344 of rod 332 may include a rod eye of diameter 252 extending through rod 332 perpendicular to a central axis of rod 332 and configured to receive a first structural element for pivotally attaching proximal end 344 of rod 332 to machine 10, such as a rod eye pin pivotally connecting rod end 34B of hydraulic cylinder 34 to work tool 14 via power link 37, as shown in fig. 1. Distal end 342 of tube 322 may similarly include a trunnion cover hole of diameter 242, with trunnion cover hole 242 extending through distal end 342 of tube 322 perpendicular to the central axis of rod 332 and tube 322 and configured to receive a trunnion pin that pivotally attaches distal end 342 of tube 322 to a second structural element of machine 10, such as a trunnion pin configured to pivotally connect head end 34A of hydraulic cylinder 34 to a portion of boom 28, as shown in fig. 1.

A diameter 252 of a rod eye extending through proximal end 344 of rod 332, a diameter of a rod eye pin configured for pivotally connecting rod 332 of each hydraulic cylinder to a structural element of machine 10, a diameter 242 of a trunnion cover hole extending through distal end 342 of tube 322, and a diameter of a trunnion pin configured for pivotally connecting tube 322 of each hydraulic cylinder to another structural element of machine 10 are determined based at least in part on the dimensions of the structural elements of machine 10 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 will be subjected under load during actuation of each hydraulic cylinder. As shown in fig. 2, pin-to-pin center-to-center distance dimension 132 of each hydraulic cylinder 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 boom 22, boom 28, and work tool 14 of each machine 10. The stroke 222 of each hydraulic cylinder shown in fig. 3 is similarly determined based at least in part on the size, range of motion, work load, and structural interrelationships of the structural elements of each machine 10. The rod 332 and piston 420 are shown fully retracted into the tube 322 in fig. 3, with the stroke 222 determined by the distance the piston 420 can walk from a fully retracted position when bottoming out at the closed distal end 342 of the tube 322 to a fully extended position of the rod 332 when the piston 420 contacts a head seal assembly 520 bolted to the rod end boss 324 of the tube 322.

Like

hydraulic cylinders

26, 32, 34, left travel motor 42L, right travel motor 42R, and swing motor 43 may each be driven by a fluid pressure differential. In particular, each of these motors may include first and second chambers (not shown) located on either side of a respective pumping mechanism, such as an impeller, plunger, or series of pistons (not shown). When the first chamber is filled with pressurized fluid and the second chamber is drained of fluid, the pumping mechanism may be forced to move or rotate in a first direction. Conversely, when the first chamber is drained of fluid and the second chamber is filled with pressurized fluid, the pumping mechanism may be urged to move or rotate in the opposite direction. The flow rate of fluid into and out of the first and second chambers may determine the output speed of the respective motor, while the pressure differential across the pumping mechanism may determine the output torque. The displacement of left travel motor 42L, right travel motor 42R, and/or swing motor 43 may alternatively be variable and of an eccentric type, if desired. In an alternative embodiment, the motors may be provided with controls and devices to support the load when changing the displacement direction so that the speed and/or torque output of each motor may be independently adjusted for a given flow rate and/or pressure of the supplied fluid.

Machine 10 may include a hydraulic system (not shown) having a plurality of hydraulic circuits that drive the aforementioned fluid actuators (hydraulic cylinders) to move work tool 14 (see fig. 1) and machine 10. Specifically, the hydraulic system may include, among other things, a first circuit, a second circuit, a third circuit, a fourth circuit, and a fifth circuit, and as one exemplary embodiment. In an exemplary embodiment, the first circuit may be primarily associated with hydraulic cylinders 32 and right travel motor 42R. The second circuit may be primarily associated with swing motor 43. The third circuit may be primarily associated with hydraulic cylinder 34. Fourth circuit may be primarily associated with left travel motor 42L and hydraulic cylinders 26. The fifth circuit may be primarily associated with an auxiliary actuator, such as an auxiliary motor or cylinder (not shown) directly associated with work tool 14. It is contemplated that additional and/or differently configured circuits may be included within the exemplary hydraulic system, such as, for example, a charging circuit associated with each of the first-fifth circuits, and/or a separate circuit associated with hydraulic cylinders 26 or 34, if desired.

In the disclosed embodiments, 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 left and right channels. In particular, each circuit may include a common left pump passage, a common right pump passage, a left actuator passage for each actuator, and a right actuator passage for each actuator. In circuits with linear actuators (e.g., hydraulic cylinders 26, 32, or 34), the left and right actuator passages are commonly referred to as head-end and rod-end passages, respectively. Within each circuit, the respective pump may be connected to its associated actuator via a combination of left, right, pump, and actuator channels.

To rotate the rotary actuator (e.g., left travel motor 42L, right travel motor 42R, and/or swing motor 43) in a first direction, the left actuator channel of a particular circuit may be filled with fluid pressurized by the pump, while the corresponding right actuator channel may be filled with fluid exiting the rotary actuator. To reverse the rotary actuator, the right actuator channel may be filled with fluid pressurized by the pump, while the left actuator channel may be filled with fluid exiting the rotary actuator.

To retract a linear actuator (e.g., hydraulic cylinders 26, 32, or 34), 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 returned from the linear actuator. Conversely, to extend the linear actuator, the left actuator channel may be filled with fluid pressurized by pump 66, 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 particular elevated pressure. That is, the pump may include a stroke-adjusting mechanism, such as a swash plate, that hydromechanically adjusts its position based on, among other things, the desired speed of the actuator, thereby changing 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 into the right pump passage at a maximum rate. The pump may be drivably connected to power source 18 of machine 10 by, for example, a countershaft, a belt, or in another suitable manner. Alternatively, the pump may be indirectly connected to power source 18 via a torque converter, a gearbox, an electrical circuit, or any other means known in the art. It is contemplated that the pumps of the different circuits may be connected to power source 18 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 be selectively operated as a motor. More specifically, when the associated actuator is operating in an overrunning condition, the fluid discharged from the actuator may have an elevated pressure that is higher than the output pressure of the respective pump. In such a case, the elevated pressure of the actuator fluid directed back through the pump may be used to drive the pump to rotate with or without assistance from power source 18. In some cases, the pump may even be capable of applying energy to power source 18, thereby increasing the efficiency and/or capacity of power source 18.

In an exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder adapted for use as hydraulic cylinder 32 in actuating boom 28 relative to boom 22, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 to a minimum equal to 3083mm ± 2.5 mm. The stroke 222 of the example boom cylinder may be equal to 2118mm ± 1.5 mm. The rod eye diameter 252 may be equal to 130mm ± 0.5 mm. Trunnion cover hole diameter 242 may be equal to 130mm + -0.5 mm. The disclosed size ranges are determined based on one or more of the following: physics-based equations, finite element analysis, empirical evidence, and other computational analysis that take into account factors such as the kinematic interrelationship between the boom and the boom on the machine, the range of motion of the respective structural components, the loads to which the hydraulic cylinder will be subjected during operation of the machine, expected fatigue life, hydraulic fluid pressure, and machine safety factors.

In another exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder adapted for use as hydraulic cylinder 26 in actuating boom 22, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 equal to 2531mm ± 2.5 mm. The stroke 222 of the example boom cylinder may be equal to 1792mm ± 1.5 mm. The rod eye diameter 252 may be equal to 140mm ± 0.5 mm. Trunnion cover hole diameter 242 may be equal to 140mm + -0.5 mm. The disclosed dimensional ranges are determined based on consideration of one or more of the following, such as kinematic interrelationships between the boom and the body of the machine, the range of motion of the respective structural components, the loads to which the hydraulic cylinder will be subjected during machine operation, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors: physics-based equations, finite element analysis, empirical evidence, and other computational analysis.

In yet another exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder adapted for use as hydraulic cylinder 34 in actuating bucket 14 relative to boom 28, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 to a minimum point equal to 2178mm ± 2.5 mm. The stroke 222 of the example boom cylinder may be equal to 1433mm ± 1.5 mm. The rod eye diameter 252 may be equal to 120mm ± 0.5 mm. Trunnion cover hole diameter 242 may be equal to 110mm + -0.5 mm. The disclosed dimensional ranges are determined based on consideration of one or more of the following, such as kinematic interrelationships between the boom, interconnecting links, and bucket of the machine and other work tools, the ranges of motion of the respective structural components, the loads to which the hydraulic cylinders will be subjected during machine operation, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors: physics-based equations, finite element analysis, empirical evidence, and other computational analysis.

In yet another exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder adapted for use as hydraulic cylinder 34 in actuating bucket 14 relative to boom 28, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 equal to 2307mm ± 2.5 mm. The stroke 222 of the example boom cylinder may be equal to 1457mm ± 1.5 mm. The rod eye diameter 252 may be equal to 130mm ± 0.5 mm. Trunnion cover hole diameter 242 may be equal to 120mm + -0.5 mm. The disclosed dimensional ranges are determined based on consideration of one or more of the following, such as kinematic interrelationships between the boom, interconnecting links, and bucket of the machine and other work tools, the ranges of motion of the respective structural components, the loads to which the hydraulic cylinders will be subjected during machine operation, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors: physics-based equations, finite element analysis, empirical evidence, and other computational analysis.

In yet another exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder adapted for use as hydraulic cylinder 32 in actuating boom 28 relative to boom 22, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 equal to 3252mm ± 2.5 mm. The stroke 222 of the exemplary boom cylinder may be equal to 2262mm ± 1.5 mm. The rod eye diameter 252 may be equal to 130mm ± 0.5 mm. Trunnion cover hole diameter 242 may be equal to 130mm + -0.5 mm. The disclosed dimensional ranges are determined based on consideration of one or more of the following, such as kinematic interrelationships between booms and booms on the machine, ranges of motion of the respective structural components, loads to which the hydraulic cylinders will be subjected during machine operation, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors: physics-based equations, finite element analysis, empirical evidence, and other computational analysis.

In yet another exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder suitable for use as hydraulic cylinder 26 in actuating boom 22, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 equal to 2827mm ± 2.5 mm. The stroke 222 of the exemplary boom cylinder may be equal to 1967mm ± 1.5 mm. The rod eye diameter 252 may be equal to 150mm ± 0.5 mm. Trunnion cover hole diameter 242 may be equal to 150mm + -0.5 mm. The disclosed dimensional ranges are determined based on consideration of one or more of the following, such as kinematic interrelationships between the boom and body of the machine, the range of motion of the respective structural components, the loads to which the hydraulic cylinder will be subjected during machine operation, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors: physics-based equations, finite element analysis, empirical evidence, and other computational analysis.

In yet another exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder adapted for use as hydraulic cylinder 34 in actuating bucket 14 relative to boom 28, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 equal to 2301 mm ± 2.5 mm. The stroke 222 of the example boom cylinder may be equal to 1451 mm ± 1.5 mm. The rod eye diameter 252 may be equal to 130mm ± 0.5 mm. Trunnion cover hole diameter 242 can be equal to 120mm + -0.5 mm. The disclosed dimensional ranges are determined based on consideration of one or more of the following, such as kinematic interrelationships between the boom, interconnecting links, and bucket of the machine and other work tools, the ranges of motion of the respective structural components, the loads to which the hydraulic cylinders will be subjected during machine operation, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors: physics-based equations, finite element analysis, empirical evidence, and other computational analysis.

In yet another exemplary embodiment of a hydraulic cylinder according to the present disclosure, such as a hydraulic cylinder adapted for use as hydraulic cylinder 34 in actuating bucket 14 relative to boom 28, the hydraulic cylinder may have a pin-to-pin dimension 132 when fully retracted, wherein rod 332, piston retaining assembly 430, and piston 420 bottom out at closed distal end 342 of tube 322 equal to 2576 mm ± 2.5 mm. The stroke 222 of the exemplary boom cylinder may be equal to 1586 mm ± 1.5 mm. The rod eye diameter 252 may be equal to 150mm ± 0.5 mm. Trunnion cover hole diameter 242 may be equal to 130mm + -0.5 mm. The disclosed dimensional ranges are determined based on consideration of one or more of the following, such as kinematic interrelationships between the boom, interconnecting links, and bucket of the machine and other work tools, the ranges of motion of the respective structural components, the loads to which the hydraulic cylinders will be subjected during machine operation, expected fatigue life, hydraulic fluid pressures, and mechanical safety factors: physics-based equations, finite element analysis, empirical evidence, and other computational analysis.

Industrial applicability

The disclosed hydraulic cylinders may be applied to any machine where the application of specific performance dimensions for the stroke of each hydraulic cylinder, pin-to-pin center distance length, rod eye pin diameter, and trunnion cover pin diameter is based at least in part on the results of physics-based equations. Finite element analysis, empirical data, structural analysis, and kinematic analysis of various structural elements of a particular machine require that a particular task, such as a boom, and a work tool of an excavator, be performed to actuate relative to one another by hydraulic cylinders. The specific performance dimensions for each hydraulic cylinder on a particular machine may be determined based at least in part on various computational analyses including fatigue analysis of structural elements under load, relative positions of coupling points at which head and rod ends of the hydraulic cylinder will be pivotally connected, hydraulic system pressures, hoop, bending, torsional, shear, compressive and tensile stresses on various components of each hydraulic cylinder, and other mechanical design considerations.

During operation of machine 10, an operator located within operator station 20 may command particular movements of work tool 14 in desired directions and at desired speeds via interface device 46. One or more corresponding signals generated by interface device 46 may be provided to an electronic controller along with machine performance information indicative of a desired movement of structural components interconnected by one or more of the disclosed hydraulic cylinders, such as sensor data including hydraulic fluid pressure data, position data, speed data, acceleration data, pump displacement data, and other data known in the art.

In response to the signals from interface device 46 and based on the machine performance information, the controller may generate control signals that are directed to pumps, motors, and/or valves that control, for each hydraulic cylinder, the flow of hydraulic fluid to a head-end chamber on one side of the piston and a rod-end chamber on the opposite side of the piston. In one exemplary embodiment, to rotate right travel motor 42R at an increased speed in a first direction, 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. In addition, the controller may generate a control signal that causes the switching valve to move towards and/or remain in one of the two flow-through positions. After fluid from the right pump channel enters and passes through right travel motor 42R, the fluid may return to the pump via the left pump channel. At this point, the speed of right travel motor 42R may depend on the discharge rate of the pump and the amount of restriction (if any) provided by the switching valve to the fluid flow through right travel motor 42R. The movement of right travel motor 42R may be reversed by moving the switching valve to the other of the two flow-through positions.

Hydraulic cylinder 32 may be moved simultaneously with right travel motor 42R and/or independently of right travel motor 42R. In particular, when right travel motor 42R receives fluid from the pump, one or more metering valves may be moved to divert some fluid into head end chamber 352 or rod end chamber 354 of hydraulic cylinder 32. At the same time, each metering valve may be moved to direct waste fluid from hydraulic cylinder 32 back to the pump. When the switching valve and appropriate metering valve are fully open, the movement of right travel motor 42R and hydraulic cylinder 32 may be correlated and dependent on the flow rate of fluid from the pump.

To provide independent control of the speed of right travel motor 42R and hydraulic cylinder 32, fluid flow to and/or from at least one of these actuators must be metered. For example, the switching valve and/or the metering valve may be moved to an intermediate position in which fluid flow therethrough is restricted to a certain extent. When this occurs, the speed of one or both actuators may be adjusted as desired. Operation of hydraulic cylinders 26 and 34, as well as left travel motor 42L, swing motor 43, and auxiliary motors may be accomplished in a manner similar to that described above. Therefore, a detailed description of the respective movements of these actuators will not be described in the present invention.

During some operations, the flow rate of fluid provided to each actuator from its associated pump may be insufficient to meet the operator's demand. For example, during a boom-up operation of hydraulic cylinders 26, an operator may desire a speed of machine 10 that would require a flow rate of fluid within the fourth circuit that exceeds a capacity of the associated pump. In this case, the controller may cause the valve element of the corresponding combination valve to, for example, transfer fluid from the second hydraulic circuit to the fourth hydraulic circuit, thereby increasing the flow rate of fluid available to hydraulic cylinders 26. At this time, fluid discharged from hydraulic cylinders 26 may return to the pump of the fourth circuit and the pump of the second circuit via the combination valve. Flow sharing between other circuits via other combining valves may be achieved in a similar manner.

Sharing fluid between hydraulic circuits that direct fluid to a particular hydraulic cylinder or other actuator may be particularly advantageous due to situations where additional flow is required for a particular circuit. Specifically, during a digging operation, hydraulic cylinders 26 may require additional flow and, at the same time, the pump of the circuit that provides pressurized hydraulic fluid to the travel motor may be idle at this time. Thus, the full capacity (flow rate and pressure control) of the idle circuit is available when the circuit supplying pressurized hydraulic fluid to the hydraulic cylinders is most needed. This may not always be the case for other circuits. For example, sharing fluid between idle circuits may be inefficient, provide little benefit, and/or reduce control over circuit operation.

Flow sharing may also be selectively achieved when the amount of fluid displaced from one actuator exceeds the rate at which the corresponding pump can effectively consume return fluid. For example, during boom lowering operations, fluid may be drained from head end chamber 352 of hydraulic cylinder 26 under high pressure as boom 22 moves under the force of gravity. Some of this exhaust fluid may be redirected back into rod end chamber 354 of hydraulic cylinder 26 via a metering valve. This operation may be referred to as regeneration and results in an increase in efficiency of supplying fluid relative to the pump directed into the rod end chamber 354. However, during regeneration, the amount of fluid displaced from the head end chamber 352 is greater than the amount of fluid entering the rod end chamber 354 due to the presence of the portion of the rod 332 within the rod end chamber 354. Thus, this additional fluid exiting the head end chamber 352 must be consumed somewhere. In various exemplary embodiments, the additional fluid displaced from hydraulic cylinders 26 during boom down motion may be directed through pumps associated with different circuits. This extra-high pressure fluid may be used to drive a pump acting as a motor, thereby returning energy to the hydraulic system.

In the disclosed embodiments, the flow provided by the various pumps may be substantially unrestricted during many operating conditions, such 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. Furthermore, the ability to combine fluid flows from different circuits to meet the needs of individual actuators 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, improve overall efficiency, improve packaging of the hydraulic system, and/or reduce costs of the hydraulic system. All of the above-discussed considerations of sharing pressurized hydraulic fluid between certain hydraulic circuits and cylinders of the machine, as well as considerations of regeneration when returning energy to the hydraulic system, may also take into account computational analysis used in determining performance dimensions of each cylinder, such as stroke size, pin-to-pin center distance size, trunnion cap hole and trunnion pin diameters, and rod eye pin diameters.

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

Claims

1. An actuator configured for actuating a first structural element on a machine relative to a second structural element on the machine, characterized in that the actuator comprises:

a piston mounted at a distal end of the rod;

the diameter of the rod eye hole is equal to 150mm +/-0.5 mm; and

the diameter of the trunnion cover hole is equal to 150mm +/-0.5 mm.

2. The actuator of claim 1, wherein the first structural element comprises a body of an excavator.

3. The actuator of claim 2, wherein the second structural element comprises a boom of the excavator.

4. The actuator of claim 1, further comprising a damping assembly disposed at the closed distal end of the tube adjacent the distal end of the rod when the rod is fully retracted into the tube.

5. The actuator of claim 4, wherein the damping assembly axially protrudes from the closed distal end radially centrally located portion of the tube.

6. The actuator of claim 5, wherein the damping assembly is configured to be received within a mating blind hole formed in the distal end of the rod when the rod is fully retracted into the tube.

7. The actuator of claim 1, further comprising a damping assembly retained within a blind bore in the distal end of the rod, the damping assembly configured to enter a radially centrally located axial bore in the closed distal end of the tube when the rod is fully retracted into the tube.

8. The actuator of claim 1, further comprising an axially-oriented relief bore extending into the closed distal end of the tube, the relief bore extending parallel to and offset from a central axis of the tube, penetrating into the closed distal end of the tube, and intersecting a radially-oriented relief bore extending between a relief compartment defined in a distal end of the tube and an outer perimeter of the tube.

9. The actuator of claim 1, wherein the head seal assembly is threaded onto and disposed on a rod end boss at the proximal end of the tube.

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

a piston mounted at a distal end of the rod;

the diameter of the rod eye hole is equal to 150mm +/-0.5 mm; and

the diameter of the trunnion cover hole is equal to 150mm +/-0.5 mm.