WO2016201241A1 - 3d printed solid piston with internal void - Google Patents

3d printed solid piston with internal void Download PDF

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Publication number
WO2016201241A1
WO2016201241A1 PCT/US2016/036908 US2016036908W WO2016201241A1 WO 2016201241 A1 WO2016201241 A1 WO 2016201241A1 US 2016036908 W US2016036908 W US 2016036908W WO 2016201241 A1 WO2016201241 A1 WO 2016201241A1
Authority
WO
WIPO (PCT)
Prior art keywords
piston
cylinder
internal
support members
truss
Prior art date
Application number
PCT/US2016/036908
Other languages
French (fr)
Inventor
Kyle Joseph Merrill
Robert STAKELY
Willem KUYVENHOVEN
Thomas Gregory FINSEL
Original Assignee
Parker-Hannifin Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US201562173668P priority Critical
Priority to US62/173,668 priority
Application filed by Parker-Hannifin Corporation filed Critical Parker-Hannifin Corporation
Publication of WO2016201241A1 publication Critical patent/WO2016201241A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04BPOSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B53/00Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
    • F04B53/14Pistons, piston-rods or piston-rod connections
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER
    • B22F10/00Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20Direct sintering or melting
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER
    • B22F5/00Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/008Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of engine cylinder parts or of piston parts other than piston rings
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER
    • B22F5/00Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/10Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of articles with cavities or holes, not otherwise provided for in the preceding subgroups
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B33ADDITIVE MANUFACTURING TECHNOLOGY
    • B33YADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00Products made by additive manufacturing
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04BPOSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/122Details or component parts, e.g. valves, sealings or lubrication means
    • F04B1/124Pistons
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04BPOSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B27/00Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders
    • F04B27/08Multi-cylinder pumps specially adapted for elastic fluids and characterised by number or arrangement of cylinders having cylinders coaxial with, or parallel or inclined to, main shaft axis
    • F04B27/0873Component parts, e.g. sealings; Manufacturing or assembly thereof
    • F04B27/0878Pistons
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER
    • B22F10/00Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/10Formation of a green body
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00Technologies related to metal processing
    • Y02P10/25Process efficiency

Abstract

A piston (800) for a piston pump includes an attachment portion (804) configured to attach the piston to the piston pump; and a cylinder portion (802) having an internal cavity (820) fluidly isolated from the environment by an outer wall (830) of the cylinder portion (802). The piston (802) may be 3D-printed and thus avoid welding defects and substantially reduce weight. Internal structural members (812,813) may reinforce a relatively thin outer wall (830) to reduce the weight of the piston (800). The piston (800) may comprise an internal conduit (850) connecting upper surface of the piston (800) with the attachment portion (804). The piston (800) for a piston pump, preferably an axial piston pump, may be manufactured by additive manufacturing (AM) methods such as selective laser melting (SLM), direct material laser sintering (DMLS), selective laser sintering (SLS) or alternatively by fused deposition modelling (FDM).

Description

3D PRINTED SOLID PISTON WITH INTERNAL VOID
Field of Invention
The present invention relates generally to piston pumps, and more
icularly to pistons having complex internal structure for use with piston pumps.
Background
Solid pistons have higher efficiency than hollow pistons. However, a heavier piston causes a decrease in the maximum speed capability of the pump/motor.
Because of this, the majority of pistons in pump/motors are hollow to achieve higher operating speeds. Some solid piston designs utilize an inertia welding process to lessen the weight. This is a difficult and expensive process.
3D printing or additive manufacturing (AM) refers to any of the various processes for manufacturing a three-dimensional object by adding material, rather than by removing it. However, AM processes may include one or more steps in which material is removed and still be considered 3D printing or additive
manufacturing. Thus, primarily additive processes are used, in which successive layers of material are laid down, usually under computer control.
Summary of Invention
AM allows novel light weight "solid" pistons. Presented are exemplary solid pistons with internal voids that may be implemented with AM. For example exemplary embodiments include internal voids containing a lattice structure or a lower-density material that would help prevent fluid from permeating or being stored in the void. A lattice or truss system allows a high strength-to-weight ratio compared to traditional methods of adding more material to have a stronger part. The external shell of the piston may be continuous material to prevent fluid from getting inside the piston. The internal passage to port high pressure fluid from one end of the piston to the other may also be continuous material without seams. The thickness of these continuous materials can be thinner than conventional pistons, because the lattice or truss system connecting these two surfaces will provide the needed strength. The lattice or truss system can be varied depending on where the highest stresses are occurring on the piston. This will result in a piston that has material only where the material is required to provide functionality and strength. It is noted that after the piston is additively manufactured, one or more finishing steps— such as exterior machining to produce desired surface finishes— are possible.
According to one aspect of the invention, a piston for a piston pump, includes an attachment portion configured to attach the cylinder to the piston pump; and a cylinder portion having an annular internal cavity extending radially between an outer wall of the cylinder portion and an inner wall of the cylinder portion, the inner wall circumscribing an internal passage of the piston. The cylinder portion further includes one or more internal support members extending from the inner wall to the outer wall within the internal cavity.
In accordance with the invention, the structure of the piston can be formed in a continuous manner using AM, i.e. the material of the piston is continuous and absent seams that otherwise exist in pistons, such as weld seams formed by an inertia weld process.
Optionally, the one or more internal support members includes a transverse support member oriented perpendicular to a longitudinal axis of the piston.
Optionally, the one or more internal support members includes a skewed support member oriented at an angle skewed with respect to a longitudinal axis of the piston.
Optionally, the one or more internal support members include an annular support member.
Optionally, the one or more internal support members include a truss support member.
Optionally, the one or more internal support members include a first truss member and a second truss member, and wherein the cylinder portion includes a bracing member extending from the first truss member to the second truss member. Optionally, the bracing member is curved.
Optionally, the first truss member is circumferentially spaced from the second truss member.
Optionally, the first truss member is 45 degrees offset from the second truss member.
Optionally, the first truss member is 90 degrees offset from the second truss member.
Optionally, the one or more internal support members includes a group of internal support members located midway along a longitudinal length of the internal cavity.
Optionally, the one or more internal support members includes a group of internal support members located adjacent a junction between the cylinder portion and the attachment portion of the piston.
Optionally, the one or more internal support members includes a transverse support member extending along an entire longitudinal length of the cavity.
Optionally, the cylinder portion is free from welding artifacts.
Optionally, the piston is made via additive manufacturing.
According to another aspect, a piston for a piston pump includes an attachment portion configured to attach the cylinder to the piston pump; and a cylinder portion having an annular internal cavity extending radially between an outer wall of the cylinder portion and an inner wall of the cylinder portion, the inner wall circumscribing an internal passage of the piston. The outer wall includes an increased thickness portion providing increased rigidity at a location of heightened stress.
Optionally, the cylinder portion further includes one or more internal support members extending from the inner wall to the outer wall within the internal cavity
Optionally, the cylinder portion is free from welding artifacts.
According to another aspect, a piston for a piston pump includes an attachment portion configured to attach the cylinder to the piston pump; and a cylinder portion having an internal cavity fluidly isolated from the environment by an outer wall of the cylinder portion. The cylinder portion is free from welding artifacts.
Optionally, the outer wall includes an increased thickness portion providing increased rigidity at a location of heightened stress.
Optionally, the internal cavity is an annular internal cavity extending radially between the outer wall of the cylinder portion and an inner wall of the cylinder portion, the inner wall circumscribing an internal passage of the piston.
Optionally, the cylinder portion further includes one or more internal support members extending from the inner wall to the outer wall within the internal cavity.
Optionally, the one or more internal support members includes a transverse support member oriented perpendicular to a longitudinal axis of the piston.
Optionally, the one or more internal support members includes a skewed support member oriented at an angle skewed with respect to a longitudinal axis of the piston.
Optionally, the one or more internal support members include an annular support member.
Optionally, the one or more internal support members include a truss support member.
Optionally, the one or more internal support members include a first truss member and a second truss member, and wherein the cylinder portion includes a bracing member extending from the first truss member to the second truss member.
Optionally, the bracing member is curved.
Optionally, the first truss member is circumferentially spaced from the second truss member.
Optionally, the first truss member is 45 degrees offset from the second truss member.
Optionally, the first truss member is 90 degrees offset from the second truss member. Optionally, the one or more internal support members includes a group of internal support members located midway along a longitudinal length of the internal cavity.
Optionally, the one or more internal support members includes a group of internal support members located adjacent a junction between the cylinder portion and the attachment portion of the piston.
Optionally, the one or more internal support members includes a transverse support member extending along an entire longitudinal length of the cavity.
Optionally, the piston is made via additive manufacturing.
Optionally, the piston includes a fluid passage extending from a cylinder end surface to an attachment end surface, and wherein an opening of the passage on the cylinder end surface is radially spaced from a center of the cylinder end surface.
The foregoing and other features of the invention are hereinafter described in greater detail with reference to the accompanying drawings.
Brief Description of the Drawings
FIG. 1 shows a longitudinal cross-section of an exemplary piston having internal structural support members along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 2 shows a longitudinal cross-section of another exemplary piston having internal structural support members along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 3 shows a longitudinal cross-section of another exemplary piston having internal structural support members placed at high-stress areas along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 4 shows a longitudinal cross-section of another exemplary piston having one or more internal structural support members halfway along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston; FIG. 5 shows a transverse cross-section taken through an exemplary annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 6 shows a transverse cross-section taken through another exemplary annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 7 shows another exemplary piston having one or more internal structural support members halfway along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston, and one or more internal structural support members at a juncture between a cylinder portion and an attachment portion of the piston;
FIG. 8 shows another exemplary piston having internal structural support members along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 9 shows another exemplary piston having internal structural support members along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 10 shows another exemplary piston having internal structural support members along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 11 shows an exemplary piston having an annular cavity defined between an inner wall and an outer wall having a varying thickness along its length of the cylinder portion of the piston;
FIG. 12 shows an exemplary piston having one or more internal structural support members along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston;
FIG. 13 shows an exemplary piston having an asymmetrical transverse cross-section with an internal cavity and a fluid passage running between the cavity and an outer wall of the piston; and FIG. 14 shows another exemplary piston having an asymmetrical transverse cross-section with an internal cavity and a fluid passage running between the cavity and an outer wall of the piston. Detailed Description
As mentioned, presented herein are non-exhaustive examples of solid pistons with internal voids that may be implemented with AM. For example, some exemplary embodiments include internal voids containing a lattice structure. The lattice or truss system can be varied depending on where the highest stresses are occurring on the piston. This results in a piston that has material only where the material is required to provide functionality and strength.
Benefits of exemplary pistons include lower cost and higher quality parts. In conventionally-made pistons having internal voids, costs include inertia welding and finish machining that would be unnecessary in an exemplary piston. As the cost of 3D printing of metal decreases, this would be a preferred method of manufacture from just a cost perspective. Additionally the part would have a better strength-to- weight ratio increasing the performance of the pump/motor.
Conventional pistons are inertia welded in two locations which results in a larger void and a lighter piston. The inertia weld location in some conventional pistons is by the neck of the piston and may fail due to weld quality and
consistency, filling the piston with oil and negating the light weight benefits if the piston does not merely crack and destroy the entire pump. Other conventional pistons include just one inertia weld location at the top of the piston. The internal void consisted of five drilled holes. This second conventional piston is a more reliable design than the first conventional piston described, but the weight of the piston is higher (e.g., 2.2 lbs versus 1.93 lbs for a 14% increase).
Exemplary pistons may weigh less than the current conventional designs, have the same or better strength capability,, and have improved performance and reliability. Advanced shapes such as a lattice structure would provide even better weight-to-strength ratios and are possible with AM, but not with existing manufacturing techniques. In particular, 3D printing utilizing high performance polymers or metals enables exemplary designs.
Three-dimensional (3D) printable models may be created with a computer aided design package or via 3D scanner. Based on this data, 3D models of the scanned object can then be produced.
Before printing a 3D model from a 3D electronic file, it must first be processed by software (conventionally known as a "slicer") which converts the model into a series of adjacent cross-sectional layers and produces an instruction set or file containing instructions tailored to a specific 3D printer.
The 3D printer follows the instructions to lay down successive layers of material (e.g., liquid, powder, or paper) to build the object from a series of cross- sections. These layers are joined or automatically fused to create the final object. Conventional printer resolution (layer thickness and X-Y resolution) is around 100 pm (250 DPI).
Exemplary pistons may be made by any appropriate AM technique, and several of these methods are described below, although exemplary embodiments may be made using still further techniques.
Selective laser melting (SLM) is an AM process that uses a high-power laser beam (usually an ytterbium fiber laser) to create three-dimensional metal parts by fusing fine metallic powders together. Thin layers of atomized fine metal powder are evenly distributed using a coating mechanism onto a substrate plate that is fastened to an indexing table that moves relative to the surface of the powder, generally in the vertical (Z) axis. This takes place inside a chamber containing a tightly controlled atmosphere of inert gas, either argon or nitrogen, with oxygen levels below 500 parts per million. Once each layer of powder has been distributed, each slice of the object to be manufactured is fused by selectively applying the laser energy to the powder surface. The laser energy is intense enough to permit full melting (welding) of the particles to form solid metal. The process is repeated layer after layer until the part is complete. The types of materials that can be processed include stainless steel, tool steel, cobalt chrome, titanium & aluminum. Direct metal laser sintering (DMLS) techniques use a laser to sinter powdered material (typically metal) together to create a solid structure. DMLS is similar to SLM, described above, but in SLM the material is fully melted rather than sintered, allowing for different properties (crystal structure, porosity, etc.). DMLS machines conventionally use a high-powered 200 watt Yb-fiber optic laser. Inside the manufacturing area, there is a material dispensing platform and a build platform along with a recoater blade used to move new powder over the build platform. The types of materials that can be processed include stainless steel, maraging steel, cobalt chromium, and titanium.
Selective laser sintering (SLS) (similar to both DMLS and SLM)
conventionally uses a high power (typically pulsed) laser (for example, a carbon dioxide laser) to fuse small particles of plastic, metal, ceramic, or glass powders on the surface of a powder bed. The particles are conventionally preheated in the powder bed to reduce the laser power required for fusing. After each cross-section is fused, the powder bed is lowered by one layer thickness, a new layer of material is applied on top, and the process is repeated until the object is completed.
Fused deposition modeling (FDM) (also known as fused filament fabrication (FFF)) conventionally provides material for the object to be manufactured via a plastic filament or metal wire that is unwound from a coil. This material is supplied to an extrusion nozzle which can turn the flow on and off. A worm-drive may push the filament into the nozzle at a controlled rate. The nozzle is heated to melt the material or to heat thermoplastics past their glass transition temperature. The nozzle can be moved in both horizontal and vertical directions by a numerically controlled mechanism. Materials used in FDM include thermoplastics such as acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and polycarbonate; polyamides; polystyrene; lignin; and many others.
It is noted that other manufacturing methods and materials may be used in addition to those listed above, including methods and materials not currently known.
Referring first to FIG. 1 , shown is a top half of an exemplary piston 100 shown in longitudinal cross-section. The piston has a cylindrical portion 102 which acts to pump fluid connected to an attachment portion 104. The attachment portion 104 may take the form of any known attachment portion in the art and is preferably, as shown, approximately spherical so as to for a ball and socket joint with and enable articulation of the piston with respect to the swashplate of the piston pump. As shown in FIG. 14, the attachment portion may also be, for example, a generally spherical hollow to form the female side of the ball and socket joint, rather than the male side.
The piston 100 has a passage 150 extending from a cylinder end surface 106 to an attachment end surface 108 to port fluid from one side of the piston to the other during operation.
The piston 100 includes an annular cavity 120 defined between an outer wall 130 and an inner wall 140 of the cylinder portion 102 of the piston. The inner wall 140 of the cylinder portion of the piston surrounds the passage 150 and separates the passage 150 from the internal cavity 120. The annular cavity 120 may have any appropriate length, and in this case extends from the cylinder end wall 132 to a transition wall 134 between the cylinder portion 102 of the piston and the
attachment portion 104.
In the present embodiment, the inner and outer walls 130, 140 have uniform thickness along their length, although a varying wall thickness of either wall is also possible. If the wall thickness varies, it is preferable that the variable wall surface is limited to being the wall surface defining the cavity so as not to interfere with piston functioning.
The piston 100 has internal structural support members 110 along the length of the cavity 120. These support members include transverse support members 112 that are oriented perpendicular to the longitudinal axis 160 of the piston 100 and skewed support members 114 that are angled with respect to the longitudinal axis 150. The skewed support members 114 may be any angle, and are preferably angled at between 30 and 60 degrees. As shown, not all skewed support members 114 need be angled identically. The internal support members 110 may be annular support members. An annular transverse support member, therefore, would be shaped like a washer, extending radially outward from the inner wall 140 to the outer wall 130. Likewise, an annular skewed support member 114 would, therefore, be shaped like the outer surface of a cone with a hole through the middle. Such supports are shown in FIG. 10, for example. With one or more solid annular supports, the internal cavity would be divided into two or more chambers that are isolated from one another. It is possible to include one or more passages through such support members to fluidly connect these multiple chambers. If an inner or outer wall was ever compromised during operation and fluid entered the inside of the cylinder, having solid walls would prevent fluid from filling the entire cavity. Alternatively, connecting multiple chambers together would allow the fluid to propagate throughout the cylinder portion of the piston.
Alternatively or additionally, internal support members 110 may be truss members circumferentially spaced from each other. Examples of truss members are described in more detail below with reference to FIG. 5, for example.
Turning now to Fig. 2, an exemplary embodiment of the piston is shown at 200. The piston 200 is substantially the same as the above-referenced piston 100, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing description of the piston 100 is equally applicable to the piston 200 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
In particular, piston 200 includes only transverse support members 212, skewed support members being entirely absent from this embodiment.
Turning now to Fig. 3, an exemplary embodiment of the piston is shown at 300. The piston 300 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 300 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 3 shows a longitudinal cross-section of another exemplary piston having internal structural support members placed at high-stress areas along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston. In particular, a group of internal support members 316 are located midway along the length of the internal cavity where stress from pressure would be at a heightened level as compared with stress in other locations. Further, a second group of internal support members 318 is located adjacent the interface between the cylinder portion 302 and the attachment portion 304 of the piston where stress may be relatively higher due to a change in surface shape of the piston.
Turning now to Fig. 4, an exemplary embodiment of the piston is shown at 400. The piston 400 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 400 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 4 shows a longitudinal cross-section of another exemplary piston having one or more internal structural support members 412 halfway along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston. This may be a single annular support member, or may be a series of multiple truss-type support members circumferential ly spaced from each other.
Turning now to Fig. 5, an exemplary embodiment of the piston is shown at 500. The piston 500 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 500 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 5 shows a transverse cross-section taken through an exemplary annular cavity defined between an outer and an inner wall of the cylinder portion of the piston. The section shows eight transverse support members 512 that reinforce the relatively thin outer wall 530 of the piston 500. As will be apparent to one having ordinary skill in the art, a different number of support members may be included. Although it is preferable to evenly space these members about the circumference of the piston, it is possible to make the cylinders asymmetrical about the longitudinal axis. If evenly spaced, a preferred spacing for eight members is then 45 degrees. Four members would be spaced 90 degrees apart. It is also possible to include, at a second transverse cross-section taken longitudinally spaced from this cross- section, a set of support members that are either of the same or a different number. Further, this second set may be rotated about the longitudinal axis 550 with respect to the first set, if desired.
Turning now to Fig. 6, an exemplary embodiment of the piston is shown at 600. The piston 600 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 600 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 6 shows a transverse cross-section taken through another exemplary annular cavity defined between an outer and an inner wall of the cylinder portion of the piston. The section shows eight transverse support members 612 that reinforce the relatively thin outer wall 630 of the piston 600. All variations mentioned above with respect to FIG. 5, and others apparent to those skilled in the art upon reading and understanding the present disclosure, are equally applicable to this
embodiment. Additionally, bracing members 613 are included and extend from one support member 612 to an adjacent support member 612. Although shown curved, these bracing members 613 may also be straight.
Turning now to Fig. 7, an exemplary embodiment of the piston is shown at
700. The piston 700 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 700 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 7 shows another exemplary piston having one or more internal structural support members halfway along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston, and one or more internal structural support members at a juncture between a cylinder portion and an attachment portion of the piston. These may be single annular support members, or may be a series of multiple truss-type support members
circumferentially spaced from each other. It is further noted that the piston includes an annular internal cavity 705 in the attachment portion 704. This cavity 705 may be connected to the cavity 720 or may be separate.
Turning now to Fig. 8, an exemplary embodiment of the piston is shown at 800. The piston 800 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 800 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable. FIG. 8 shows another exemplary piston having internal structural support members 812 along the length of an annular cavity 820 defined between an outer and an inner wall of the cylinder portion of the piston. These support members 812 are formed in a group located approximately half way along the length of the annular cavity 820. It is noted that these truss-style support members 812 are coupled with bracing members 813 to form a lattice structure as in FIG. 6. Further, it is noted that these members include filleted connections between the bracing members 813 and the support members 812 as well as between the support members 812 and the walls 830, 840. These filleted connections provide additional strength at these connections and allow the members to support additional bending stresses at these connections. Fillets in 3D space on joints between trusses and at the juncture of trusses with the remainder of the piston would significantly reduce stress in the structure when compared with conventional pistons, and these would be incredibly difficult if not impossible to produce in an enclosed envelope of a conventional piston. Conventional inertia weld process make it hard to get a low- stress nicely-rounded connection. With a poor inertia welded, connection high stresses occur and the pistons can fail
Turning now to Fig. 9, an exemplary embodiment of the piston is shown at 900. The piston 900 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 900 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 9 shows another exemplary piston having internal structural support members 912 along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston. Similar to FIG. 8, this embodiment includes filleted connections between the support members 912 and the inner and outer walls 930, 940. Turning now to Fig. 10, an exemplary embodiment of the piston is shown at 1000. The piston 1000 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 1000 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 10 shows another exemplary piston having annular skewed internal structural support members 1014 along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston. These members split the internal cavity 1020 into a series of isolated annular chambers. Further, piston 10 includes an annular cavity 1005 in the attachment portion to further lower weight of the piston.
Turning now to Fig. 11 , an exemplary embodiment of the piston is shown at
1100. The piston 1100 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 1100 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 11 shows an exemplary piston having an annular cavity defined between an inner wall and an outer wall having a varying thickness along its length of the cylinder portion of the piston. In particular, the outer wall includes an increased thickness portion extending from the interface with the attachment portionl 104 along approximately 40% of the length of the cavity 1120.
Turning now to Fig. 12, an exemplary embodiment of the piston is shown at 1200. The piston 1200 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 1200 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 12 shows an exemplary piston having one or more internal structural support members 1212 along the length of an annular cavity defined between an outer and an inner wall of the cylinder portion of the piston. There may be any number of such members 1212, but preferably there are 3 or 4 members 1212, dividing the cavity into 3 or 4 corresponding chambers extending along the length of the cylindrical portion.
Turning now to Fig. 13, an exemplary embodiment of the piston is shown at 1300. The piston 1300 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 1300 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 13 shows an exemplary piston having an asymmetrical transverse cross-section with an internal cavity and a fluid passage running between the cavity and an outer wall of the piston. The fluid passage 1350 runs from the end face 1306 of the cylindrical portion 1302 to the end face 1308 of the attachment portion 1304. The opening on the end face 1306 is offset from the center of the end face 1306.
Turning now to Fig. 14, an exemplary embodiment of the piston is shown at 1400. The piston 1400 is substantially the same as the above-referenced pistons, and consequently the same reference numerals but indexed by 100 are used to denote structures corresponding to similar structures in the piston. In addition, the foregoing descriptions of the pistons are equally applicable to the piston 1400 except as noted below. Moreover, it will be appreciated upon reading and understanding the specification that aspects of the pistons may be substituted for one another or used in conjunction with one another where applicable.
FIG. 14 shows another exemplary piston having an asymmetrical transverse cross-section with an internal cavity and a fluid passage running between the cavity and an outer wall of the piston. In contrast to FIG. 13, the attachment portion forms a female portion of a ball and socket joint.
The internal piston (as opposed to the external ball piston) may also include other features that allow locking and/or attachment of the mating part (shoe or slipper) to the piston added via 3D printing that avoid additional process steps such as rolling or crimping material over the ball to ensure the parts stay connected.
As may be desired, material may be added at a side diametrically opposite an internal feature of the piston, such as an internal bulge forming the inner side of the passage in the Fig. 13 or 14 embodiment, in order to counterbalance added weight arising from such internal feature, such as the material added to form the internal bulge.
Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and
understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a "means") used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.

Claims

Claims What is claimed is:
1. A piston for a piston pump, comprising:
an attachment portion configured to attach the cylinder to the piston pump; and
a cylinder portion having an annular internal cavity extending radially between an outer wall of the cylinder portion and an inner wall of the cylinder portion, the inner wall circumscribing an internal passage of the piston,
wherein the cylinder portion further includes one or more internal support members extending from the inner wall to the outer wall within the internal cavity.
2. The piston of claim 1 , wherein the one or more internal support members includes a transverse support member oriented perpendicular to a longitudinal axis of the piston.
3. The piston of any preceding claim, wherein the one or more internal support members includes a skewed support member oriented at an angle skewed with respect to a longitudinal axis of the piston.
4. The piston of any preceding claim, wherein the one or more internal support members include an annular support member.
5. The piston of any preceding claim, wherein the one or more internal support members include a truss support member.
6. The piston of any preceding claim, wherein the one or more internal support members include a first truss member and a second truss member, and wherein the cylinder portion includes a bracing member extending from the first truss member to the second truss member.
7. The piston of claim 6, wherein the bracing member is curved.
8. The piston of either one of claims 6 or 7, wherein the first truss member is circumferentially spaced from the second truss member.
9. The piston of either one of claims 6 or 7, wherein the first truss member is 45 degrees offset from the second truss member.
10. The piston of either one of claims 6 or 7, wherein the first truss member is 90 degrees offset from the second truss member.
11. The piston of any preceding claim, wherein the one or more internal support members includes a group of internal support members located midway along a longitudinal length of the internal cavity.
12. The piston of any preceding claim, wherein the one or more internal support members includes a group of internal support members located adjacent a junction between the cylinder portion and the attachment portion of the piston.
13. The piston of any preceding claim, wherein the one or more internal support members includes a transverse support member extending along an entire longitudinal length of the cavity.
14. The piston of any preceding claim, wherein the cylinder portion is free from welding artifacts.
15. The piston of any preceding claim, wherein the piston is made via additive manufacturing.
16. A piston for a piston pump, comprising:
an attachment portion configured to attach the cylinder to the piston pump; and
a cylinder portion having an annular internal cavity extending radially between an outer wall of the cylinder portion and an inner wall of the cylinder portion, the inner wall circumscribing an internal passage of the piston,
wherein the outer wall includes an increased thickness portion providing increased rigidity at a location of heightened stress.
17. The piston of claim 16, wherein the cylinder portion further includes one or more internal support members extending from the inner wall to the outer wall within the internal cavity
18. The piston of any one of claims 16 or 17, wherein the cylinder portion is free from welding artifacts.
19. A piston for a piston pump, comprising:
an attachment portion configured to attach the cylinder to the piston pump; and
a cylinder portion having an internal cavity fluidly isolated from the environment by an outer wall of the cylinder portion,
wherein the cylinder portion is free from welding artifacts.
20. The piston of claim 19, wherein the outer wall includes an increased thickness portion providing increased rigidity at a location of heightened stress.
21. The piston of any one of claims 19-20, wherein the internal cavity is an annular internal cavity extending radially between the outer wall of the cylinder portion and an inner wall of the cylinder portion, the inner wall circumscribing an internal passage of the piston.
22. The piston of claim 21 , wherein the cylinder portion further includes one or more internal support members extending from the inner wall to the outer wall within the internal cavity.
23. The piston of any one of claims 19-22, wherein the one or more internal support members includes a transverse support member oriented perpendicular to a longitudinal axis of the piston.
24. The piston of any one of claims 19-23, wherein the one or more internal support members includes a skewed support member oriented at an angle skewed with respect to a longitudinal axis of the piston.
25. The piston of any one of claims 19-24, wherein the one or more internal support members include an annular support member.
26. The piston of any one of claims 19-25, wherein the one or more internal support members include a truss support member.
27. The piston of any one of claims 19-26, wherein the one or more internal support members include a first truss member and a second truss member, and wherein the cylinder portion includes a bracing member extending from the first truss member to the second truss member.
28. The piston of claim 27, wherein the bracing member is curved.
29. The piston of either one of claims 27 or 28, wherein the first truss member is circumferentially spaced from the second truss member.
30. The piston of either one of claims 27 or 28, wherein the first truss member is 45 degrees offset from the second truss member.
31. The piston of either one of claims 27 or 28, wherein the first truss member is 90 degrees offset from the second truss member.
32. The piston of any one of claims 19-31 , wherein the one or more internal support members includes a group of internal support members located midway along a longitudinal length of the internal cavity.
33. The piston of any one of claims 19-32, wherein the one or more internal support members includes a group of internal support members located adjacent a junction between the cylinder portion and the attachment portion of the piston.
34. The piston of any one of claims 19-33, wherein the one or more internal support members includes a transverse support member extending along an entire longitudinal length of the cavity.
35. The piston of any one of claims 19-34, wherein the piston is made via additive manufacturing.
36. The piston of any one of claims 19-35, wherein the piston includes a fluid passage extending from a cylinder end surface to an attachment end surface, and wherein an opening of the passage on the cylinder end surface is radially spaced from a center of the cylinder end surface.
37. The piston of any preceding claim, wherein the attachment portion includes an annular internal cavity.
38. A piston formed by an AD process, the piston having an internal cavity completely surrounded by a wall structure of continuous material that is free of seams.
PCT/US2016/036908 2015-06-10 2016-06-10 3d printed solid piston with internal void WO2016201241A1 (en)

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US62/173,668 2015-06-10

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WO2019081238A1 (en) * 2017-10-27 2019-05-02 Robert Bosch Gmbh Plunger, in particular a roller plunger, for a pump and pump having a plunger
CN110360095A (en) * 2019-08-20 2019-10-22 四川航天烽火伺服控制技术有限公司 Plunger assembly and plunger pump with the component
IT201900001613A1 (en) 2019-02-05 2020-08-05 Dana Motion Sys Italia Srl Piston for axial piston hydraulic machines.
WO2020173520A1 (en) * 2019-02-25 2020-09-03 Schaeffler Technologies AG & Co. KG Piston, axial piston engine and method for producing a piston
US11112009B2 (en) 2020-04-03 2021-09-07 Cummins Inc. Low heat transfer piston via binder jet technology

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EP2784313A1 (en) * 2013-03-25 2014-10-01 Liebherr Machines Bulle SA Piston for an axial piston machine
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EP2784313A1 (en) * 2013-03-25 2014-10-01 Liebherr Machines Bulle SA Piston for an axial piston machine
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Publication number Priority date Publication date Assignee Title
WO2019081238A1 (en) * 2017-10-27 2019-05-02 Robert Bosch Gmbh Plunger, in particular a roller plunger, for a pump and pump having a plunger
IT201900001613A1 (en) 2019-02-05 2020-08-05 Dana Motion Sys Italia Srl Piston for axial piston hydraulic machines.
US11092174B2 (en) 2019-02-05 2021-08-17 Dana Motion Systems Italia S.R.L. Pistone for hydraulic machines with axial pistons
WO2020173520A1 (en) * 2019-02-25 2020-09-03 Schaeffler Technologies AG & Co. KG Piston, axial piston engine and method for producing a piston
CN110360095A (en) * 2019-08-20 2019-10-22 四川航天烽火伺服控制技术有限公司 Plunger assembly and plunger pump with the component
CN110360095B (en) * 2019-08-20 2021-03-02 四川航天烽火伺服控制技术有限公司 Plunger assembly and plunger pump with same
US11112009B2 (en) 2020-04-03 2021-09-07 Cummins Inc. Low heat transfer piston via binder jet technology

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