GB2587317A

GB2587317A - Lightweight hydraulic cylinder

Info

Publication number: GB2587317A
Application number: GB1909852.4A
Authority: GB
Inventors: David Screation Lee
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-07-09
Filing date: 2019-07-09
Publication date: 2021-03-31
Also published as: GB201909852D0

Abstract

A hydraulic cylinder with a 3d printed jacket comprises a structurally loaded jacket 200, an unloaded diffusion barrier or sleeve 300, head assembly 400, end cap assembly 500, piston assembly 600, bolt assembly 700 and oilways. The jacket surrounds the diffusion barrier and is mounted between the head assembly and end cap assembly, secured by the bolt assembly. The piston assembly is translatably disposed within the diffusion barrier and through the end cap and comprising of multiple components assembled along a rod that extend and retract along a longitudinal axis. The oil pathways allow the movement of oil to increase and decrease oil pressure within chambers to cause the piston assembly to translate in a longitudinal fashion to the diffusion barrier based on the pressure differential between the entering and exiting oil. The use of 3D manufacturing processes allows the jacket to be designed such that it features optimized structures and void spaces to eliminate unstressed elements. In combination with a diffusion barrier, the jacket can be constructed from porous materials or in a structural manner that would not readily contain the fluid within the assembly or serve as a suitable bearing surface for the piston to pass across.

Description

FIELD OF INVENTION

[0001] The invention is generally related to the design and manufacturing of hydraulic cylinders, more particularly, to reduce the weight of large hydraulic cylinders through the use of emerging technology and manufacturing methods.

[0002] A hydraulic cylinder is a commonly used linear actuation component typically constructed from metal or metal alloy manufactured using traditional methods such as casting, machining, boring and welding. Hydraulic cylinders are available in a wide variety of orientations and sizes however large hydraulic cylinders are heavy due to the requirement to have a tubular body that must resist structural loads such as bending and buckling and operational loads such as hoop, axial and radial stress.

[0003] A conventional hydraulic cylinder consists of a thick walled tube, known as the cylinder body, which is sealed at either end by two structural elements; the head and the end cap. The arrangement features a piston assembly that includes a rod, piston and rod end. Within the piston assembly and head there are various seals and rubbing strips to assist with the mechanical sealing and wear associated with the movement of the piston assembly through the head. The cylinder body, end cap and/ or the head include machined fluid paths for the inlet and outlet of hydraulic oil. The piston travels in a linear fashion within the cylinder body through the ingress and egress of hydraulic oil at either side of the piston thereby creating a pressure differential.

[0004] The use of a simple tube as the cylinder body allows for traditional calculations to be performed for the most efficient structure within the possibilities of a tube however the use of a tube reduces the effectiveness of modern calculation techniques such as finite element analysis (FEA) which is employed primarily to optimize structural arrangements. The use of FEA would allow for the reduction or the removal of material that is not contributing to the structural effectiveness of the mechanism. The invention makes use of modern manufacturing techniques, specifically 3D printing, that greatly enhances the ability of the engineer to optimize the structure using FEA and similar optimization approaches.

[0005] The weight of a hydraulic cylinder can greatly influence its effectiveness in a system especially when the cylinder is of the larger variety. For example, cylinders used on large luffing boom cranes can weigh almost the same weight as the boom itself which reduces the efficiency of the overall system. The invention is intended to provide a hydraulic cylinder of equal mechanical, structural and functional properties to an equivalent traditional hydraulic cylinder but with a significant reduction in the overall weight of the component. The invention also allows the cylinder designer a greater flexibly in the choice of materials for the cylinder body assembly which has cost, manufacturing and operational advantages over traditional approaches.

PRIOR ART

[0006] While there are in existence various light weight hydraulic cylinders, for example the lightweight cylinder supplied by Parker Hydraulics U.S. patent ref. U55415079A, and their T series products, the approach adopted has been to replace the cylinder body with exotic materials such as composites, resins or carbon fibre mat. This technique has significant weight saving advantages over traditional metal tubes however the costs involved in the materials and manufacturing make them expensive when compared to a traditional similarly sized cylinder. There are also issues with robustness and longevity that is inherent with the use of materials such as carbon fibre mat. The invention allows a greater degree of optimization of the jacket structure through analysis which can then be manufactured primarily using 3D printing rather than machining, welding and other conventional techniques.

[0007] Elaborate hydraulic cylinder walls that feature void spaces such as that featured within U.S. patent ref. US5267388A illustrate the advantages of employing 3D printing techniques for complex structures. In order to piece together the structural elements that could not be fabricated in a single structure, the arrangement referenced above requires high precision tongue and groove connections and fasteners which is an expensive and considerably dimensionally intolerant production method. The primary advantage of 3D printing is that structures can be created that feature embedded elements that are only evident during production and inaccessible upon completion. When compared to casting and extrusion for example, 3D printing can create continuous structures without any need for access to remove material or longitudinal clearance for any forming process. When compared with welding and discrete elements such as those shown within U.S. patent ref. US5267388A, the load distribution throughout a 3D printed structure, as described in this invention, is more linear and continuous.

[0008] As implied, there are in existence a variety of hydraulic cylinders and some feature weight saving methods. The key difference between the prior art and this invention is that this hydraulic cylinder invention uses a general arrangement of thin unloaded diffusion barrier, also traditionally referred to as a sleeve or liner, and an optimised 3D printed jacket for all stresses (hoop, axial and radial) that allows for a highly optimized arrangement when so required.

SUMMARY OF INVENTION

[0009] Embodiments of the invention address the above identified needs by providing a hydraulic cylinder that greatly improves the ability of engineering and manufacturing techniques to provide a light weight hydraulic cylinder.

[0010] The apparatus comprises primarily of a body assembly that consists of a thin cylindrical diffusion barrier which is mounted within a structurally supportive surrounding jacket. The body assembly is sealed at either end with a head assembly and an end cap assembly. An additional piston assembly passes through the head assembly with the piston within the body assembly and the rod end outside the cylinder assembly as a whole. The diffusion barrier is sealed against the head assembly and end cap to prevent the loss of any hydraulic fluid. The diffusion barrier also acts as the bearing or sliding surface that allows the piston of the piston assembly travel linearly along the length of the inside of the body assembly. The jacket is held in place by the head and end cap assemblies and secured through the use of bolts, screws, tension rods or a threaded cap arrangement. The connection points to the cylinder assembly are through an eye or trunnion on the end cap or trunnion included on the body assembly as well as an eye or other form of connection on the exposed end of the piston assembly. The means of actuating the cylinder assembly can be through the increase of pressure in hydraulic oil on one side of the piston within the body assembly. This increase in pressure is a consequence of injecting oil to one side the piston through oilways in either the head assembly or the end cap assembly. Conversely, as oil pressure is increased on one side of the piston, oil is allowed to exit on the opposite side of the piston via oilways in either the head assembly or the end cap assembly. Depending on whether oil enters via the head assembly and exits via the end cap assembly or vice versa, the piston assembly will travel in a linear fashion along the body assembly thereby extending or retracting the rod end.

[0011] The jacket is engineered to take the primary loading such as the hoop, axial and radial loads and will be optimized such that void spaces and structural elements distribute the load as necessary for the intended use of the assembly. As the diffusion barrier acts as both the diffusion barrier and the bearing surface, the jacket may be non-solid by featuring void spaces. Additionally, there would be a greater allowance for lower finishing tolerances and diverse materials could be employed as required by the optimization engineering. The jacket will be fabricated using 3D printing technology so that any structure required by the optimised engineering can be realized.

[0012] The invention differs from a traditional hydraulic cylinder in that the use of an arrangement consisting of an unloaded diffusion barrier and supportive jacket, constructed through the use of 3D printing techniques, allows for a highly optimized structure that is independent of the constraints of a tubular based design, composite design or discrete element structure.

[0013] The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For a better understanding of the present invention, and the operating advantages attained by its use, reference is made to the accompanying drawings and descriptive matter, forming a part of this disclosure, in which a preferred embodiment of the invention is illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the accompanying drawings, forming a part of this specification, and in which reference numerals shown in the drawings designate like or corresponding parts throughout the same: [0015] FIG. 1 and 4 shows perspective views of a hydraulic cylinder apparatus in accordance with an illustrative embodiment of the invention [0016] FIGS. 2, 3, 5 and 6 show a partially broken or exploded perspective view of the FIG. 1 and 4 hydraulic cylinder apparatus.

[0017] FIG. 7 shows a perspective view of a diffusion barrier or sleave [0018] FIG. 8 shows a perspective view of a head assembly [0019] FIG. 9 shows a perspective view of a piston assembly [0020] FIG. 10 shows a perspective view of an end cap assembly [0021] FIG. 11 shows a perspective view of a jacket [0022] FIG. 12 shows a perspective view of a set of securing bolts [0023] FIG. 13 shows a sectional illustration of a jacket [0024] FIGS. 13A, 13B, 13C and 13D show horizontal sections through the jacket of FIG 13 [0025] FIG. 13E shows a vertical section through the jacket of FIG 13 [0026] FIG. 14 shows a cutaway through the jacket of FIG 13 [0027] FIGS. 15 and 16 show perspective views of a head assembly [0028] FIG. 17 shows a sectional illustration of a head assembly [0029] FIG. 17A shows a vertical section through the head assembly of FIG 17 [0030] FIG. 17B shows a horizontal section through the head assembly of FIG 17 [003 I] FIGS. 18 and 19 show perspective views of an end cap assembly [0032] FIG. 20 shows a sectional illustration of an end cap assembly [0033] FIG. 20A shows a vertical section through the end cap assembly of FIG 20 [0034] FIG. 20B shows a horizontal section through the end cap assembly of FIG 20 DESCRIPTION OF THE PREFERRED EMBODIMENTS [0035] The present invention will be described with reference to illustrative embodiments. For this reason, numerous modifications can be made to these embodiments and the results will still come within the scope of the invention. No limitations with respect to the specific embodiments described herein are intended or should be inferred.

[0036] FIGS. I to 6 show aspects of a hydraulic cylinder apparatus (100) in accordance with an illustrative embodiment of the invention. FIGS. 1 and 4 show perspective views of the illustrative hydraulic cylinder apparatus (100), while FIGS. 2 and 5 show a partially-broken perspective view of the hydraulic cylinder apparatus (100) illustrating the arrangement minus the jacket (200). FIGS. 3 and 6 show a partially-broken perspective view of the hydraulic cylinder apparatus (100) illustrating the arrangement with an illustrative reduced diffusion barrier (301).

[0037] In the hydraulic cylinder apparatus (100), a jacket (200) surrounds a diffusion barrier (300) that is sealed by a head assembly (400) and end cap assembly (500). The piston assembly (600) includes a piston (602) that traverses the diffusion barrier (300) in a linear fashion. The piston (602) connects to the rod end (601) by a rod (603) that passes through the end cap (400). A set of bolts (700) secures the head assembly (400) and end cap assembly (500) to the jacket (200).

[0038] FIGS. 7 to 12 show components of a hydraulic cylinder apparatus (100) in accordance with an illustrative embodiment of the invention. FIG. 7 shows a perspective view of a diffusion barrier (300). FIG. 8 shows a perspective view of a head assembly (400). FIG. 9 shows a perspective view of a piston arrangement (600). FIG. 10 shows a perspective view of an end cap assembly (500). FIG. 11 shows a perspective view of a jacket (200). FIG. 12 shows a perspective view of a set of bolts (700).

[0039] The piston assembly (600) consists of a rod end (601) that is connected to a rod (603) and a piston (602) that is held in place against a shear stop (608) by a securing nut (607). The piston features wear rings (604 and 606) and one or more seals (605).

[0040] The set of bolts (700) feature bolts (701), washers (702) and securing nuts (703). The bolts (701) pass through holes in a jacket (201), holes in a head assembly (401) and holes in an end cap assembly (501) and are held in tension by a washer (702) and nut (703) combination.

[0041] FIGS. 13 to 14 show sectional and cutaway views of a jacket (300) component of a hydraulic cylinder apparatus (100) in accordance with an illustrative embodiment of the invention. FIG. 13 is an illustration of the various sectional views of a jacket (300) shown in FIGS. 13A to 13E. FIGS. 13A to 13D show horizontal sections through a jathet (300) while FIG I 3E shows a vertical section through a jacket (300).

[0042] The jacket (300) features void spaces (302), structural elements (303) and allows the passage of other components such as a set of bolts (700) through holes (301).

[0043] FIGS. 15 to 17 show sectional and perspective views of a head assembly (400) of a hydraulic cylinder apparatus (100) in accordance with an illustrative embodiment of the invention. FIGS. 15 and 16 are perspective views of the head assembly (400). FIG. 17 is an illustration of the horizontal sectional views shown in FIGS. 17A and 17B.

[0044] The head assembly (400) allows the passage of the piston rod (603) of the piston assembly (600) through an opening (402) in the external surface (409). Embedded within the opening (402) is a wiper seal (405), fluid seal (406) and wear ring (407). The wider opening (410) in the internal surface (411) includes a fluid seal (408) that seals against the diffusion barrier (300). Between the opening in the external surface (402) and the opening in the internal surface (410) is a chamber that includes an oilway (404) that connects to a hydraulic fitting connection point (403).

[0045] FIGS. 18 to 20 show sectional and perspective views of an end cap assembly (500) of a hydraulic cylinder apparatus (100) in accordance with an illustrative embodiment of the invention. FIGS. 18 and 19 are perspective views of the end cap assembly (500). FIG. 20 is an illustration of the horizontal sectional views shown in FIGS. 20A and 20B.

[0046] The end cap assembly (500) includes a wide opening (502) in the internal surface (507) which features a fluid seal (505) that seals against the diffusion barrier (300). Within the end cap assembly there is a chamber (506) that includes an oilway (504) that connects to a hydraulic fining connection point (503).

[0047] Once understood from the teachings herein, various elements forming the above-described hydraulic cylinder apparatus (100) may be formed from conventional materials utilizing conventional manufacturing techniques, or alternatively, obtained commercially. The head assembly (400), the end cap assembly (500), the piston assembly (600), and their associated appendages, for example, are preferably formed from a metals such as, but not limited to steel and aluminium, with a protective paint or coating suitable for marine use where applicable. When not available commercially, these components may be custom manufactured utilizing conventional metal forming techniques, which will be familiar to one skilled in the relevant metal forming arts.

[0048] The jacket (200) may be formed from any material that is both suitable for the loading expressed in the engineering and able to be manufactured using one of the various 3D printing techniques including but not limited to fused deposition modeling (FDM), fused filament fabrication (FFF), stereolithography (SLA), digital light processing (DLP), selective laser sintering (SLS), material jetting (MB, drop on demand (DOD), binder jetting (BB, direct metal laser sintering (DMLS), selective laser melting (SLM) and electron beam melting (EBM).

[0049] The diffusion barrier (300) may be formed from conventional materials utilizing conventional manufacturing techniques, or alternatively, obtained commercially. The diffusion barrier (300) is preferably formed from metal such as, but not limited to steel although alternative materials such as plastic, ceramic or carbon fibre may prove suitable after appropriate engineering has proven their diffusion barrier and bearing surface properties. When not available commercially, these components may be custom manufactured utilizing conventional manufacturing techniques.

[0050] The seals (405)(406)(605), wear rings (407)(604)(606), bolts (701), washers (702) and nuts (703) may be obtained commercially. Suitable seals (405)(406)(605) and the wear rings (407)(604)(606) may, for example, be obtained from Parker Hannifin (Warwick, UK). Suitable bolts (701), washers (702) and nuts (703) are available from, for example, Clarendon Specialty Fasteners (Devon, UK).

[0051] The hydraulic cylinder apparatus (100) provides several advantages. Fundamentally, reducing the weight of a major mechanical component such as a hydraulic cylinder can significantly improve the capacity of a mechanism. Additionally, a light weight hydraulic cylinder arrangement can improve a mechanisms practicality in terms of where the mechanism can be installed and operated and its likely cost when the cost of materials are considered.

[0052] By way of example for the benefits in reducing cylinder weights, large cylinders are frequently featured on high capacity offshore systems such as A Frames (launch and recovery systems), construction cranes such as knuckle boom cranes and mechanized structures such as pipelay towers. Such large cylinders can weigh many tonnes that add to the overall weight of the mechanism they are being used to actuate. For example, the weight of the boom section of a knuckle boom crane must include the weight of at least one cylinder (the knuckle actuation arrangement) which implies a high load at the pivot point in the crane structure. Reducing the weight of the cylinders can have a significant impact to the pivot point loads as the cylinder weight is a product of the distance of the cylinder from the pivot, hence any weight reduction being

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significant. Less weight in the key actuation components means less weight to the overall structure which has impacts on the marine vessel in terms of deck strengthening, ballasting and cargo loads.

[0053] It should again be emphasized that the above-described embodiments of the invention are intended to be illustrative only. Other embodiments can use different types and arrangements of elements for implementing the described functionality. These numerous alternative embodiments within the scope of the appended claims will be apparent to one skilled in the art.

[0054] While a regular pattern is shown throughout the jacket (200) in the hydraulic cylinder apparatus (100), additional embodiments of the invention may utilize a different pattern based on their particular applications engineering or material. Alternative embodiments may, as just a few examples, utilize circular void spaces or even an organic style of honeycomb structure without a fundamental redesign of the system or components. The hydraulic cylinder apparatus in accordance with aspects of the invention are therefore scalable. As would be predicted, different jacket structures can increase the load capacity, reduce weight or tailor the structure specifically to the task of a hydraulic cylinder apparatus.

[0055] Alternative embodiments of the invention may, as another example, not utilize an end cap but instead feature two head assemblies and a support trunnion in order to provide a double acting cylinder with a piston rod assembly exiting both ends. As hydraulic cylinders have many arrangements including but not limited to single acting, double acting and telescopic, this invention can be applied without a fundamental redesign of the system or components.

[0056] It should also be recognized that, while the sets of bolts (700) in the illustrative, non-limiting hydraulic cylinder apparatus (100) utilize multiple bolts (701) coupled to the washers (702) and bolts (703), alternative embodiments may utilize very different arrangements of bolts or securing arrangements for performing that function. Instead of utilizing four bolts, alternative embodiments may, for example, comprise less bolts, more bolts, screwed rod or tension cables rather than bolts, a threaded head assembly or end cap assembly that screws into the jacket or diffusion barrier, or some combination thereof. Thus, it is reinforced that the arrangement of bolts in the illustrative hydraulic cylinder apparatus (100) is exemplary only and is non-limiting with respect to the scope of the present invention.

[0057] All the features disclosed herein may be replaced by alternative features serving the same, equivalent, or similar purposes, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

Claims

Claims What is claimed s: I. An apparatus for use in combination with 3D printing manufacturing techniques, the apparatus comprising: * a 3D printed jacket; * a diffusion barrier; * a head assembly, the head assembly mounted to the jacket and diffusion barrier and comprising a head structure, seals and wear ring; * an end cap assembly, the end cap assembly mounted to the jacket and diffusion barrier and comprising an end cap structure and seals; * a piston assembly, the piston assembly translatably disposed within the diffusion barrier and through the end cap and comprising of multiple components assembled along a rod that extend and retract along a longitudinal axis; * a bolt assembly, the bolt assembly arranged to secure the head assembly and end cap assembly to the jacket comprising of multiple bolts, washers and nuts; * oil pathways, the oil pathways allow the movement of oil to increase and decrease oil pressure within chambers to cause the piston assembly to translate in a longitudinal fashion to the diffusion barrier based on the pressure differential between the entering and exiting oil.
2. The apparatus of claim 1, wherein the head assembly comprises a head structure seal or seals, wear ring or wear rings.
3. The apparatus of claim 1, wherein the end cap assembly comprises an end cap structure and seal or seals.
4. The apparatus of claim 1, wherein the piston assembly comprises rod end or rod ends, rod, shear stop, piston, seal or seals, wear ring or rings, nut or nuts.
5. The apparatus of claim 1, wherein the bolt assembly comprises bolt or bolts or threaded rod or rods, washer or washers, nut or nuts.
6. The apparatus of claim I, wherein the rod end features an interface point, trunnion, hook or a ring.
7. The apparatus of claim 1, wherein the end cap assembly features and interface point, trunnion, hook or a ring.
8. The apparatus of claim 1, wherein the flow of oil is operative to cause the piston assembly to translate longitudinally to the diffusion barrier in a direction dictated by the pressure differential between the entering and existing flows of oil.
9. The apparatus of claim 1, wherein the jacket comprises a 3D printed structure.
10. The apparatus of claim 1, wherein the jacket structure disperses the majority of the hoop, axial and radial loads.
II. The apparatus of claim 1, wherein the diffusion barrier is thinly constructed and disperses very little of the hoop, axial and radial loads.
12. The apparatus of claim 1, wherein the diffusion barrier acts as both a barrier to the fluid with assembly and as a bearing surface for the piston assembly.
13. The apparatus of claim 1, further comprising a spring and single oilway so as to promote single acting hydraulic operation
14. The apparatus of claim 1, further comprising a telescopic rod arrangement so as to promote telescopic hydraulic operation
15. The apparatus of claim 1, further comprising a trunnion point that is at some point along the hydraulic cylinder assembly such as the jacket or head assembly as opposed to a connection at the end cap assembly.
16. The apparatus of claim 4, further comprising a notch or step in the rod that allows the piston to be held in place by the nut or fastener at the end of the rod.
17. The apparatus of claim 5, further comprising a head assembly or end cap assembly that features a screw arrangement that secures to a thread in the jacket or diffusion barrier.
18. The apparatus of claim 1, further comprising: * an articulating mechanical device comprising of a support component or structure and an actuating component or structure; * connection arrangement, the connection arrangement attached to the support component or structure; and * a structure or component to be actuated; * wherein the apparatus is supported by the connection arrangement of the supporting component or structure, and the structure or component to be actuated is connected to the apparatus.
19. The apparatus of claim 18, wherein the apparatus is included to reduce the weight of the articulating mechanical device by the use of 3D printing of the jacket element in combination with a separate diffusion barrier.
20. A method for reducing hydraulic cylinder weight, the method comprising the steps of: (a) engineering the jacket structure for structural efficiency; (b). engineering the dispersal of the loads such that the jacket assumes the majority of the hoop, axial and radial loads and the diffusion barrier assumes as little loads as possible (c) fabricate a jacket structure using a 3D printing manufacturing process (d) assemble a hydraulic cylinder apparatus comprising: (i) a 3D printed jacket; (ii) a diffusion barrier; (iii) a head assembly; (iv) an end cap assembly, (v) a piston assembly, the piston assembly translatably disposed within the diffusion barrier and through the end cap and comprising of multiple components assembled along a rod that extend and retract along a longitudinal axis (vi) a securing bolt assembly (AT) oil pathways, the oil pathways allow the movement of oil to increase and decrease oil pressure within chambers to cause the piston assembly to translate in a longitudinal fashion to the diffusion barrier based on the pressure differential between the entering and exiting oil (e) install the apparatus within the articulating mechanical device