CN217355010U

CN217355010U - Actuator and paver

Info

Publication number: CN217355010U
Application number: CN202220872039.2U
Authority: CN
Inventors: T·M·詹宁斯; J·D·斯佩泽尔
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2021-05-12
Filing date: 2022-04-15
Publication date: 2022-09-02
Anticipated expiration: 2032-04-15
Also published as: AU2021102496A4

Abstract

The utility model provides an actuator and paver, the actuator includes the pipe, the pipe has central axial extension hole, central axial extension hole is injectd in the pipe and extends between the closed distal end of pipe and the opening near-end of pipe, and the pipe has the interface to be used for the first structural element of pipe connection to paver. A 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 at the distal end of the rod and is retained on the rod by a piston retention assembly attached to the distal end of the rod. A rod eye for receiving the rod eye pin is defined through the proximal end of the rod. The distance from the connection interface to the center of the rod eye defines the retracted inter-pin dimension when the rod and piston are fully retracted into the tube. The stroke dimension is defined 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 paver

Technical Field

The present disclosure relates generally to a hydraulic cylinder for heavy machinery, such as a paving machine, and more particularly to a hydraulic cylinder having specific performance dimensions that meet the kinematic, structural, and load requirements of the machinery.

Background

Conventional hydraulic systems on heavy machinery, such as paving machines, 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 use in moving the actuators. The actuators may include hydraulic cylinders specifically designed to meet various kinematic, structural, and load requirements to move 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 pressures, kinematics, torsional stresses, compressive stresses, tensile stresses, hoop stresses, range of motion, and speed of motion required when operating a particular machine to perform a work task, such as transferring asphalt or other paving material from a hopper via one or more augers for application to a roadway using a floating screed. 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, fluid flow from the pump into the actuator is only slightly restricted (or not restricted at all). Conversely, to move the same actuator or another actuator at a low speed, the restriction to fluid flow is increased. While suitable for many applications, the use of fluid restriction to control actuator speed may result in pressure losses, thereby reducing 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 a pair of actuators operating in tandem. During operation, the pump draws fluid from one chamber of an actuator and discharges pressurized fluid into an opposite chamber of the same actuator. 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 fluid at a slower rate. 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 as much fluid as is required to move the actuator at the desired speed, and no throttling of the fluid is required.

An exemplary closed loop hydraulic system is disclosed in U.S. patent 4,369,625 to Izumi et al, published in 1983 at 25/1 (the' 625 patent). In the' 625 patent, a multi-actuator meterless hydraulic system having flow combining functionality is described. The hydraulic system includes a swing circuit, a boom circuit, an arm circuit, a bucket circuit, a left travel circuit, and a right travel circuit. Each of the swing, boom, stick, and bucket circuits 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 circuit and the arm circuit, a second combination valve is connected between the arm circuit and the boom circuit, and a third combination valve is connected between the bucket circuit and the boom circuit. The left and right travel circuits are connected in parallel to the pumps of the bucket and the boom circuit, respectively. 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.

Although an improvement over existing closed-loop hydraulic systems, the closed-loop hydraulic system of the' 625 patent may still be less than optimal. In particular, the connecting loops of the system can only be performed sequentially. In addition, it may be difficult to control the speed and force of the various actuators. Furthermore, the hydraulic cylinder is preferably designed to have a specific size range for the following parameters depending on the particular machine and load application in which the hydraulic cylinder will be used: the stroke (or difference between the total length of the cylinder when fully extended and fully retracted), the length between the pins when the cylinder is fully retracted (or more generally, the distance between a first connection interface at the rod end of the piston of the cylinder and a second connection interface at the opposite head end of the cylinder), the inner diameter of the tube or barrel forming the body of the cylinder, the outer diameter of the tube or barrel, the diameter of the piston rod (which extends from the piston assembly slidably supported within the tube to define a head end chamber on one side of the piston assembly and a rod end chamber on the opposite side of the piston assembly), and in some cylinders, either with a rod eye through the proximal end of the piston rod or with a trunnion cap hole at the head end of the cylinder, the aforementioned parameters also include the diameter of the rod eye pin that engages the rod eye and the diameter of the trunnion pin that engages the trunnion cap hole at the head end of the cylinder.

SUMMERY OF THE UTILITY MODEL

The present invention provides an actuator and paver, the hydraulic cylinder being designed to have a range of specific performance dimensions, the range being determined by a combination of extensive analysis including the application of physics-based equations, finite element analysis and other computational analysis taking into account kinematic and structural stresses to be imposed on the hydraulic cylinder during use, with empirical data and other customer-centric data, the data being intended to meet specific operational requirements and to solve one or more of the technical problems mentioned above and/or other technical problems of the prior art.

An actuator configured for actuating a first structural element on a paving machine relative to a second structural element on the paving 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, the tube having a connection interface for connecting the tube to the first structural element of the paving machine;

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

a piston mounted at a distal end of the rod;

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

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

The distance from the connection interface to the center of the rod eye when the rod and the piston are fully retracted into the tube such that the distal end of the rod is located near the closed distal end of the tube is equal to 350.5 mm ± 2.5 mm;

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 open proximal end of the tube is equal to 1140.0 mm ± 1.5 mm;

the diameter of the rod is equal to 31.75 mm +/-0.5 mm;

the diameter of the pipe hole is equal to 63.5 mm +/-0.5 mm; and is

The external diameter of the tube is equal to 73.5 mm plus or minus 0.5 mm.

The diameter of the rod eye hole is equal to 25.2 mm +/-0.1 mm.

The first structural element comprises an auger of the paving machine.

The second structural element comprises a screed of the paver.

The first structural element comprises a portion of a screed plate on the paving machine or the first structural element comprises a hopper on the paving machine.

The first structural element comprises a frame or body of the paver and the second structural element comprises a screed of the paver.

Actuation of the first structural element relative to the second structural element results in at least one of: a change in inclination of a portion of the paving machine, a change in direction of movement of the paving machine, a change in tension between the first structural element and the second structural element, or a change in distance between the first structural element and the second structural element.

In the above technical solution, the actuator is a hydraulic cylinder.

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

a piston mounted at a distal end of the rod;

A distance from the connection interface to a center of the rod eye when the rod and the piston are fully retracted into the tube such that the distal end of the rod is located near the closed distal end of the tube is equal to 350.5 mm ± 2.5 mm;

a stroke dimension of the piston from a first fully retracted position 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 open proximal end of the tube is equal to 1140.0 mm ± 1.5 mm;

the diameter of the rod is equal to 31.75 mm +/-0.5 mm;

the diameter of the pipe hole is equal to 63.5 mm +/-0.5 mm; and is

The external diameter of the tube is equal to 73.5 mm plus or minus 0.5 mm.

In one aspect, the present disclosure is directed to an actuator configured to actuate a first structural element of a paving machine relative to a second structural element of the paving machine. The actuator may comprise a tube (sometimes referred to as a cylinder), wherein the tube comprises a central axially extending bore defined therein, the central axially extending 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 an aperture of the tube. A stem is slidably mounted within the tube, the stem being slidably supported at a proximal end of the tube by a head seal assembly. A piston may be mounted at the distal end of the rod. A first connection interface at the proximal end of the piston rod is configured for connecting the proximal end of the piston rod to a first structural element of the paving machine. A second connection interface at the distal end of the tube is configured to connect the distal end of the tube to a second structural element of the paving machine.

In another aspect, the present disclosure is directed to a paving machine that includes a plurality of structural elements and a plurality of hydraulic actuators each configured to interconnect in two of the structural elements, wherein each hydraulic actuator is configured to actuate with respect to a second structural element on the paving machine a first structural element on the paving machine. Each hydraulic actuator may comprise a tube, wherein the tube comprises a central axially extending bore defined therein, the central axially extending 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 an aperture of the tube. A stem is slidably mounted within the tube, the stem being slidably supported at a proximal end of the tube by a head seal assembly. A piston may be mounted at the distal end of the rod. A first connection interface at the closed distal end of the tube is configured to connect the distal end of the tube to a first structural element of the paving machine. A second connection interface at the proximal end of the rod is configured for connecting the proximal end of the rod to a second structural element of the paving machine.

In yet another aspect, the present disclosure is directed to a hydraulic cylinder configured to actuate a first structural element on a paving machine relative to a second structural element on the paving machine. Each hydraulic cylinder may comprise a tube, wherein the tube comprises a central axially extending bore defined therein, the central axially extending 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 an aperture of the tube. A stem is slidably mounted within the tube, the stem being slidably supported at a proximal end of the tube by a head seal assembly. A piston may be mounted at the distal end of the rod. A first connection interface at the closed distal end of the tube is configured for connecting the distal end of the tube to a first structural element of the paving machine. A second connection interface at the proximal end of the rod is configured for connecting the proximal end of the rod to a second structural element of the paving machine.

The technical solution of the present invention, a hydraulic cylinder for heavy machinery may benefit from the combination of the specific performance dimensions disclosed herein and features such as damping devices and head seals that improve operating characteristics, fatigue life and performance under extreme conditions.

Embodiments of the present invention may provide improved energy usage and conservation. In addition, the ability to combine fluid flow from different circuits to meet the demands of each 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 the spatial layout of the hydraulic system, and/or reduce the cost of the hydraulic system. Applying specific performance dimensions to the stroke of the hydraulic cylinder, the inter-pin length, the rod diameter, the tube bore diameter, the tube outside diameter, the rod eye pin diameter, and the trunnion cap pin diameter based at least in part on the results of structural and kinematic analyses of various structural elements of a particular paving machine required to perform certain tasks associated with a paving process also improves the efficiency and quality of paving operations, extends the useful life of the machine, and reduces the occurrence of machine component failures or the need for repair or maintenance.

Drawings

1A-1C illustrate an example hydraulic cylinder that may be used to raise and lower an auger of an asphalt paving machine;

fig. 2A-2C illustrate another example hydraulic cylinder that may be used as an extended hydraulic cylinder for various purposes of moving portions of a paving machine relative to one another.

Detailed Description

The hydraulic cylinders illustrated in fig. 1A-2C are exemplary hydraulic cylinders that may be used as actuators on a paving machine or other heavy machinery having multiple systems and components that cooperate to accomplish a task. For example, an asphalt paving machine may include various hydraulic cylinders that act as actuators for moving various portions, components, or component assemblies of the paving machine relative to one another and/or relative to a substrate on which the paving machine operates. Asphalt pavers are commonly used to apply, spread and compact a paving material, i.e., a mat of asphalt or other paving material, relatively evenly over a work surface. These machines are commonly used for the construction of roads, parking lots and other areas. An asphalt paving machine generally includes: a hopper for receiving asphalt material from a truck or material transfer vehicle; and a conveyor system for transferring the asphalt from the hopper rearwardly for discharge onto the subgrade. The screed smoothes and compacts the asphalt material, ideally leaving a subgrade of uniform depth and smoothness.

To help achieve the desired uniform depth and smoothness and to accommodate different desired subgrade configurations, the screed assembly may include various screed sections and adjustment devices. These adjustment means can be used, for example, to vary the thickness of the underlayment and the extent of any arching and its transverse slope, as well as the configuration of the shoulder beads adjacent to the underlayment. To improve the asphalt compaction and spreading capabilities of the various screed sections, screed assemblies typically utilize a tamping mechanism. The tamping mechanism may pre-compact the asphalt before the paving material passes under the screed. The tamping mechanism may include a tamper bar and wear plates on each screed segment. The tamper bars may pre-compact the asphalt and feed the asphalt under the leveling plate for efficient spreading and further compaction on the paved surface. The wear plate may be located behind the tamper bars and may be mounted to the screed frame such that a bottom surface of the wear plate is substantially aligned with a bottom surface of the screed plate. The wear plates may be configured and positioned to act as sacrificial plates (sacrificial plates) between the tamper bars and the screed frame and screed plate to prevent damage to the screed frame and screed plate when the tamper bars reciprocate up and down relative to the wear plates during a tamping operation.

The wear plate minimizes wear and tear to the screed plate and to the screed plate frame to which the wear bar is mounted. The wear plate, which is a replaceable component, is typically mounted to the screed frame such that the bottom surface of the wear plate is above the bottom edge of the screed. In other words, the wear plates maintain a height tolerance with respect to the bottom (asphalt finished surface) plane of the screed. Such height tolerances are typically required to prevent the wear plates from protruding or otherwise extending beyond the bottom edge of the screed (and screed sections), thus leaving a pattern or mark on the paving surface as the associated screed sections compact and spread the asphalt. Existing tamper bars and wear plates may experience accelerated wear due to limitations on the amount of tamper bar material present at the interface between the surface of the tamper bar and the asphalt being tamped that experiences the greatest reaction forces from the asphalt during the tamping operation and the amount of material present at the interface between the tamper bar and the wear plate.

A paving machine includes a frame having a set of ground engaging elements, such as wheels or rails, coupled with the frame. The ground engaging members may be driven by the engine in a conventional manner. The engine may further drive an associated generator that may be used to power various systems on the paving machine. A screed assembly is operatively associated with the engine and attached at a rear end of the paving machine to spread and compact the paving material into an asphalt mat having a desired thickness, size, uniformity, arching profile, and transverse slope. The paving machine also includes an operator station having a seat and a console that includes various controls for directing the operation of the paving machine.

The paving machine also includes a hopper for storing paving material, and a conveyor system including one or more conveyors configured to move the paving material from the hopper to a screed assembly at a rear of the paving machine. One or more augers are disposed near the front end of the screed assembly to receive paving material provided by the conveyor and spread the material evenly beneath the screed assembly. The height of the auger may be adjusted via one or more height adjustment actuators (e.g., hydraulic cylinders). The screed assembly is pivotally connected to the rear of the paving machine by a pair of tow arms extending between the frame of the paving machine and the screed assembly. The tow arms are pivotally connected to the frame such that the relative position and orientation of the screed assembly with respect to the screed frame and with respect to the surface being paved can be adjusted by pivoting the tow arms, for example, to control the thickness of paving material deposited by the paving machine. To this end, a tow arm actuator is provided that is arranged and configured to raise and lower the tow arm, and thereby the screed assembly. The trailing arm actuator may be any suitable actuator, such as a hydraulic cylinder.

The screed assembly may have any of a variety of configurations known in the art, and in particular it may be a multi-zone screed having an adjustable arching profile, and may include extensions having additional screeds extending in a lateral direction to accommodate a wider paved area. A screed plate assembly is provided with a screed plate. The screed is configured to float on the paving material of the asphalt mat on the prepared paved subgrade and to "smooth" or level and compact the paving material over a base surface such as, for example, a road or subgrade. The screed can be connected, preferably by means of a carriage, to a vibration shaft which is coupled to a vibrating eccentric drive. The vibratory shaft may include an eccentrically positioned weight such that when the vibratory drive rotates the vibratory shaft, the shaft vibrates the carriage and screed plate. The vibrating screed improves the compaction and quality of the asphalt mat on the prepared paved subgrade.

The power source for the paving machine may embody 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, a power storage device, a tethered motor, or another power source known in the art. The power source may produce mechanical or electrical power output, which may then be converted to hydraulic power to move various hydraulic cylinders that act as actuators to move various portions, components, or assemblies of components or structural elements of the paving machine relative to one another and/or relative to a substrate on which the paving machine is operating. An operator station on a paving machine may include a device that receives input from a machine operator indicative of a desired machine maneuver. In particular, the operator station may include one or more operator interface devices, such as a joystick, a steering wheel, or a pedal, located near the operator seat. The operator interface device may initiate movement of the paving machine, such as travel and/or tool movement, by generating displacement signals indicative of a desired machine maneuver. As the operator moves the interface device, the operator may affect the corresponding machine movement in a desired direction at a desired speed and/or with a desired force.

As shown in fig. 1A-1C, an exemplary hydraulic cylinder 102 (which may be used as an actuator for raising and lowering an auger on a paving machine) may include a tube (or cylinder barrel) 322 and a piston assembly 420 disposed at a distal end of a rod 332 within the tube 322 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 hydraulic cylinder head and head seal assembly 520 in which the piston rod 332 extends out of the hydraulic cylinder. The first chamber 352 on the cap end side (sometimes referred to as the blind end side) of the piston assembly 420 may be considered the "head end" chamber of the hydraulic cylinder, while the second chamber 354 defined between the piston rod 332 and the tube 322 may be considered the "rod end" chamber of the hydraulic cylinder. The exemplary embodiment of the piston assembly 420 shown in FIG. 1C may be disposed at the distal end of the rod 332. The piston assembly 420 may be retained on the distal end of the rod 332 by various means, such as a piston retention assembly employing a bushing or a nut at the distal end of the piston rod 332 to retain the piston assembly 420 on the distal end of the rod 332, as shown in fig. 1C. The rod 332 may have a diameter 334, and the piston assembly 420 may further include a plurality of annular seals spaced along the periphery of the piston assembly 420 and forming a slidable seal between the piston assembly 420 and the inner circumferential surface of the tube 322 as the rod 332 and the piston assembly 420 reciprocate within the tube 322 due to changes in the pressure and/or flow rate of hydraulic fluid provided to and released from the rod-end chamber 354 and the head-end chamber 352.

Rod-end and head-

end chambers

354, 352 may each be selectively supplied with pressurized fluid and drained of the pressurized fluid to displace piston assembly 420 within tube 322, thereby extending and retracting rod 332 from tube 322 and changing the effective length of the hydraulic cylinder. Extension and retraction of the rod 332 from the tube 322 causes a portion of the machine or linkage structure connected to the rod 332 to move relative to another portion of the machine or linkage structure connected to a trunnion cap secured at the distal end 342 of the tube 322. The flow rate of fluid into and out of rod-end and head-

end chambers

354, 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 an associated linkage structure of the paving machine.

As shown in fig. 1C, the proximal end of the rod 332 may pass through a head seal assembly 520 attached at the end of the tube 322 through which the rod 332 passes. The head seal assembly 520 may include a plurality of axially spaced seals along the inner circumferential periphery of the head seal assembly 520 that are configured to form a slidable seal with the periphery of the proximal end of the stem 332. A plurality of bolts may secure the head seal assembly 520 to the rod end boss, with a portion of the head seal assembly 520 extending at least partially radially inward from the rod end boss of the tube 322 and configured to radially support the proximal end of the stem 332 as the stem 332 and the piston 420 reciprocate relative to the tube 322. The proximal end of the rod 332 may include a rod eye hole of diameter 252 extending through the rod 332 orthogonal to the central axis 344 of the rod 332 and configured to receive a rod eye pin, such as a rod eye pin that pivotally connects a rod end of a hydraulic cylinder to a first structural element of a paving machine, for pivotally attaching the proximal end of the rod 332 to the first structural element of the machine. The distal end 342 of the tube 322 may similarly include a trunnion cap hole 242 having a diameter 242 extending through the distal end 342 of the tube 322 orthogonal to the rod 332 and a central axis 344 of the tube 322 and configured to receive a trunnion pin that pivotally attaches the distal end 342 of the tube 322 to a second structural element of the machine, 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

102, 128 shown in fig. 1A-2C, the values for the different sizes of hydraulic cylinders are determined based on the particular performance requirements of the hydraulic cylinders in a particular application on a paving machine. Specific performance dimensions include, but are not limited to, tube bore diameter 324 and outer diameter 326 of each tube 322, rod diameter 334 of each rod 332, diameter 252 of a rod eye extending through a proximal end of rod 332, diameter 242 of a trunnion cap hole extending through a distal end 342 of tube 322, inter-pin length 132 between a center of the rod eye and a center of the trunnion cap hole when rod 332 is fully retracted into tube 322, and stroke 222 determined by the total distance rod 332 moves when traveling from a fully retracted position to a fully extended position within tube 322. As discussed above, the stroke of the hydraulic cylinder as defined herein is the difference between the total length of the hydraulic cylinder when fully extended and when fully retracted. As defined herein, the inter-pin length/dimension is the distance between a first (or second) connection interface at the rod end of the cylinder and a second (or first) connection interface at the opposite head end of the cylinder when the hydraulic cylinder is fully retracted. A first (or second) connection interface at the closed distal end of the tube may be configured to connect the distal end of the tube to a first structural element of the paving machine. A second (or first) connection interface at the proximal end of the rod may be configured to connect the proximal end of the rod to a second structural element of the paving machine. The first connection interface and the second connection interface may each include, but are not limited to: the hydraulic cylinder may include a bore configured to receive a pin, a clevis configured to receive a clevis pin, a trunnion mount configured to engage a structural element of the paving machine, a screw configured to engage a structural element of the machine, a ball stud mount configured to receive a spherical ball element, or any other known connection interface configured to connect each of a rod end and a head end of the hydraulic cylinder to a respective structural element of the paving machine. The rod eye hole diameter 252, and thus the rod eye pin diameter configured for pivotably connecting the rod 332 of the hydraulic cylinder to a structural element of the machine, and the trunnion cap hole diameter 242 extending through the distal end 342 of the tube 322, and thus the trunnion pin diameter configured for pivotably connecting the tube 322 of the hydraulic cylinder to another structural element of the machine, are determined based at least in part on the size of the structural elements of the paving machine to which the pins are pivotably attached, as well as the loads and structural stresses to which these elements are subjected during operation, such as shear stresses, torsional stresses, compressive stresses, and tensile stresses that will be subjected under load during actuation of each hydraulic cylinder. The inter-pin dimension 132 of the hydraulic cylinder shown in fig. 1B, or more generally, the distance between a first connection interface at the closed distal end of the tube 322 and a second connection interface at the proximal end of the piston rod 332, is determined based at least in part on the size, range of motion, work load, and structural interrelationships of the structural elements of the particular machine, such as the augers and screed of each paver. The stroke 222 of the hydraulic cylinder shown in fig. 1C is similarly determined based at least in part on the size, range of motion, work load, and structural interrelationships of the structural elements of the machine. The rod 332 and piston 420 are shown fully retracted into the tube 322 in fig. 1C, with the stroke 222 being determined by the distance from such fully retracted position when the piston 420 bottoms out at the closed distal end 342 of the tube 322 to the fully extended position of the rod 332 when the piston 420 contacts the head seal assembly 520 connected to the proximal end of the tube 322.

A paving machine may include a hydraulic system having multiple circuits that drive the above-described fluid actuators (hydraulic cylinders) to move a portion of the paving machine (such as at least one side of an auger) relative to another portion of the machine. Each of the circuits 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 of the circuits may include a pump fluidly connected to its associated actuator via a closed circuit formed by the left and right side channels. In particular, each of the circuits 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 a circuit with a linear actuator, the left and right actuator channels are commonly referred to as head-end and rod-end channels, respectively. Within each circuit, the corresponding pump may be connected to its associated actuator via a combination of left and right pump channels and 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 returned by 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 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 high pressure. That is, the pump may include a stroke adjustment mechanism, such as a swash plate, the position of which is hydro-mechanically adjusted 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 at a maximum rate to the right pump passage. The pump may be drivably connected to the power source of the paving machine by, for example, a countershaft, a belt, or by other suitable means. Alternatively, the pump may be indirectly connected to the power source via a torque converter, a gearbox, an electrical circuit, or by any other means 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), if desired.

A pump configured to provide pressurized hydraulic fluid to the hydraulic actuator may also be selectively used as a motor. More specifically, when the associated actuator is operating in an overrun condition, the rise in pressure of fluid discharged from the actuator may be higher than the output pressure of the corresponding pump. In this case, the high pressure of the actuator fluid directed back through the pump may be used to drive the pump to rotate with or without power source assistance. In some cases, the pump may even be capable of applying 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 the extension hydraulic cylinder 128 used for various purposes of moving portions of a paving machine relative to each other, as shown in fig. 2A-2C), the distance 133 between a first connection interface at a piston rod end of the cylinder and a second connection interface at an opposite head end of the cylinder may be equal to 350.5 mm ± 2.5 mm when the hydraulic cylinder is fully retracted such that the rod 332 and the piston 420 bottom out at the closed distal end 342 of the tube 322. The stroke 222 of the exemplary hydraulic cylinder may be equal to 1140.0 mm ± 1.5 mm. The tube bore diameter 324 may be equal to 63.5 mm 0.5 mm and the tube outside diameter 326 may be equal to 73.5 mm 0.5 mm. The diameter 334 of the rod 332 may be equal to 31.75 mm ± 0.5 mm. The rod eye diameter 252 may be equal to 25.2 mm ± 0.1 mm. The disclosed size ranges are determined for a particular machine based on one or more of: equations based on physics, finite element analysis, empirical evidence, historical evidence, and other computational analysis that take into account factors such as the kinematic interrelationship between the components on the machine connected with the rod end and the trunnion cap end of the hydraulic cylinder, the range of motion of the corresponding structural components, the loads to which the hydraulic cylinder will be subjected during operation of the machine, the expected fatigue life, hydraulic fluid pressures, and mechanical safety factors.

Industrial applicability

The disclosed hydraulic cylinders may be applicable to any paving machine where the application of specific performance dimensions for the stroke, inter-pin length, rod diameter, pipe hole diameter, pipe outside diameter, rod eye pin diameter, and trunnion cap pin diameter of each hydraulic cylinder is based at least in part on the results of structural and kinematic analysis of various structural elements of the particular machine needed to perform certain tasks such as adjusting the position of the paving machine's auger relative to the floating screed and/or hopper on the paving machine, raising and lowering the auger, hopper, portions of the screed, or other portions of the paving machine, steering the paving machine, and performing other tasks associated with the paving process. The particular performance dimensions of each hydraulic cylinder used on a particular machine may be determined based at least in part on physics-based equations and empirical and historical data including fatigue analysis of structural elements under load, the size of the particular machine and the environment in which the particular machine operates, the materials imposed by the machine, the relative positions of the link points in which the head and rod ends of each hydraulic cylinder will be pivotally connected, hydraulic system pressures, hoop, shear, compressive and tensile stresses on various components of each hydraulic cylinder, and other mechanical design considerations.

During operation of a paving machine, an operator may command certain movements of one or more components of the machine relative to another component of the machine or relative to the ground. For example, an operator may command movement of the auger relative to the hopper and/or the floating screed, movement of portions of the screed, movement of other portions of the paving machine relative to each other or relative to the ground, steering of the paving machine, and other movements through the interface device at a desired speed or degree. One or more corresponding signals indicative of the desired movement may be generated by the interface device and 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 directed to the pump, motor, and/or valves that control the flow of hydraulic fluid to the rodless chambers on one side of the piston and the flow of hydraulic fluid to the rod chambers 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 into the left pump passage. In addition, the controller may generate a control signal that moves the switching valve to one of the two flow-passing positions and/or remains therein. After fluid from the right pump passage enters and passes through, for example, a right travel motor or into a rodless or rod chamber of a hydraulic cylinder, fluid from the motor or from a head end or rod chamber on the opposite side of the piston assembly in the hydraulic cylinder may return to the pump via the left pump passage. 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 on 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. By moving the switching valve to the other of the two flow-through positions, the movement of the right travel motor can be reversed.

The first hydraulic cylinder may move simultaneously with and/or independently of the movement of the second hydraulic cylinder. Specifically, when the first hydraulic cylinder receives fluid from the pump, one or more metering valves may be moved to transfer some of the fluid to the 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 appropriate metering valve are fully open, the movements of the first and second hydraulic cylinders may be linked together and dependent on the flow rate of fluid from the pump.

During some operations, the flow rate of fluid provided to each hydraulic cylinder from its associated pump may be insufficient to meet operator demand. During such a condition, the controller may cause the valve elements of one or more corresponding combining valves to route fluid from one fluid flow circuit to another, 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 implemented in a similar manner.

Flow sharing may also be selectively implemented 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 or rodless chamber of another hydraulic cylinder via a metering valve. This operation may be referred to as regeneration and results in increased efficiency.

The flow rate provided by the pump on the machine may be substantially unrestricted during many operations, such that a large amount of energy does not have to be wasted during actuation. Accordingly, embodiments of the present invention may provide improved energy usage and savings. In addition, the ability to combine fluid flow from different circuits to meet the demands of each 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 hydraulic system layout, and/or reduce hydraulic system costs. Applying specific performance dimensions to the stroke of the hydraulic cylinder, the inter-pin length, the rod diameter, the tube bore diameter, the tube outside diameter, the rod eye pin diameter, and the trunnion cap pin diameter based, at least in part, on the results of structural and kinematic analysis of the various structural elements of a particular paving machine required to perform certain tasks associated with the paving process also improves the efficiency and quality of the paving 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 for actuating a first structural element on a paving machine relative to a second structural element on the paving machine, the actuator comprising:

a piston mounted at a distal end of the rod;

the diameter of the rod is equal to 31.75 mm +/-0.5 mm;

the diameter of the pipe hole is equal to 63.5 mm +/-0.5 mm; and is

The external diameter of the tube is equal to 73.5 mm plus or minus 0.5 mm.

2. The actuator of claim 1, wherein the rod eye diameter is equal to 25.2 mm ± 0.1 mm.

3. The actuator of claim 1, wherein the first structural element comprises an auger of the paving machine.

4. Actuator according to claim 3, wherein the second structural element comprises a screed of the paver.

5. The actuator of claim 1, wherein the first structural element comprises a portion of a screed on the paving machine or a hopper on the paving machine.

6. Actuator according to claim 1, wherein the first structural element comprises a frame or a body of the paver and the second structural element comprises a screed of the paver.

7. An actuator according to claim 1, wherein actuation of the first structural element relative to the second structural element results in at least one of: a change in inclination of a portion of the paving machine, a change in direction of movement of the paving machine, a change in tension between the first structural element and the second structural element, or a change in distance between the first structural element and the second structural element.

8. An actuator according to any of claims 1 to 7, wherein the actuator is a hydraulic cylinder.

9. A paver comprising an actuator as claimed in any one of claims 1 to 8.