• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    A fluid cylinder with a hollow cylinder body that is at least partially closed by a cylinder head attached thereto is disclosed. A piston is guided inside the hollow cylinder body and has a piston rod extending through the cylinder head to at least one outside of the fluid cylinder. To the outside, the fluid cylinder is fluidly sealed by at least one sealing element. According to the invention, the at least one sealing element consists of a polyethylene crosslinked by means of gamma and / or electrode radiation or chemically.
    公开号:NL2020570A
    申请号:NL2020570
    申请日:2018-03-12
    公开日:2018-09-28
    发明作者:Caspers Leo；Dupuis Leo
    申请人:Bosch Gmbh Robert；
    IPC主号:
    专利说明:

    Patent center
    The Netherlands © A PATENT APPLICATION
    © 2020570 © Application number: 2020570 © Application submitted: 12 March 2018 © Int. Cl .:
    F16J 15/16 (2018.01)
    © Priority: © Applicant (s): March 22, 2017 DE 102017204810.7 Robert Bosch GmbH in Stuttgart,Federal Republic of Germany, DE. © Application registered:September 28, 2018 © Inventor (s):Leo Caspers in Eindhoven. © Request published: Leo Dupuis in 's-Hertogenbosch. October 1, 2018 © Authorized representative:ir. C.M. Jansen et al. In The Hague.
    54) Fluid cylinder with improved sealing element and manufacturing method therefor
    57) A fluid cylinder with a hollow cylinder body that is at least partially closed by a cylinder head attached thereto is disclosed. A piston is guided inside the hollow cylinder body and has a piston rod extending through the cylinder head to at least one outside of the fluid cylinder. To the outside, the fluid cylinder is fluidly sealed by at least one sealing element. According to the invention, the at least one sealing element consists of a polyethylene crosslinked by means of gamma and / or electrode radiation or chemically.
    NL A 2020570
    This publication corresponds to the documents originally submitted.
    Fluid cylinder with improved sealing element and manufacturing method for it
    Description
    The invention relates to a fluid cylinder according to the preamble of claim 1. Furthermore, the invention relates to a manufacturing method for a fluid cylinder according to the preamble of claim 9.
    Fluid cylinders in the form of hydraulic cylinders or pneumatic cylinders for various technical applications are known from practice. These fluid cylinders are also referred to as hydraulic or pneumatic operating cylinders.
    Especially in hydraulically operating fluid cylinders there is generally a desire to make them fluid-tight if possible, so that the pressure medium for operating the fluid cylinder, for example a hydraulic oil, cannot come out through slits and resulting leaks. For this purpose sealing elements are usually used which are made of a plastic and / or rubber and which must in particular seal the area of the fluid cylinder, in particular where a piston rod of a hollow cylinder body is led out. This area is often located in or on a cylinder head of the fluid cylinder.
    Furthermore, it is known in practice that ultra high molecular weight polyethylene (also referred to as UHMWPE or UHMW-PE) is comparatively well suited as a material for sealing elements for use in fluid cylinders. Polyethylene with ultra high molecular weight has relatively good chemical and mechanical properties: it is resistant to mineral oils and hydraulic oils. Moreover, ultra high molecular weight polyethylene has favorable frictional properties, so that it is relatively well suited as a material for guiding a piston rod of the fluid cylinder. However, the expensive production of the UHMWPE is disadvantageous. Due to the high molecular weight of the UHMWPE, the viscosity of the material also increases, so that the ultra-high molecular weight polyethylene can only be processed by pressing. Injection molding or screw extrusion processing is not possible.
    Moreover, with such sealing elements, various, partly temperature-dependent mechanical wear phenomena occur as a result of aging during the product life of the fluid cylinder, such as creep and stress relaxation. As a result, such a sealing element deforms or loses its bias. It has been found that this wear causes an initially largely closed fluid cylinder to leak more and more over time, as a result of which the printing medium can escape to the outside. This requires regular maintenance of the fluid cylinder to renew the sealing elements and to ensure the tightness of the fluid cylinder.
    Against this, the invention has for its object to provide a fluid cylinder which, with structurally simple means, has an improved durability and a longer lifetime in terms of density.
    This object is achieved by a fluid cylinder with the features of claim 1 or by a method for manufacturing a fluid cylinder with the features of claim 8.
    Advantageous embodiments of the fluid cylinder according to the invention are specified in the subclaims.
    The fluid cylinder according to the invention has a hollow cylinder body, which is at least partially closed off by a cylinder head mounted thereon or attached thereto. A piston is movably guided within the hollow cylinder body and has a piston rod extending through the cylinder head to at least one outer side of the fluid cylinder. For fluid sealing of the fluid cylinder, for example outwards, the fluid cylinder has at least one sealing element, which can for instance be arranged in the vicinity of the piston rod to prevent leakage or escape of fluid on the piston rod. Alternatively, the sealing element can also be attached to the piston and abut against the hollow cylinder body. According to the invention, the at least one sealing element consists of a polyethylene crosslinked by means of gamma and / or electrode radiation or chemically.
    In this context, crosslinking or networking of the polyethylene is understood to mean that the material of the sealing element is spatially, i.e. three-dimensionally, spatially networked by a suitable processing process before the completion of a sealing element and / or is installed in the fluid cylinders or introduced therein. The result is an additional cross-linking of the polyethylene chains. The additional cross-linking or the additional networking of the polyethylene has the advantage for the sealing member that the sealing element has an elastically deformable shape, but still has a relatively large form factor retention or shape resistance and a relatively high dimensional accuracy and shape stability. Pre-stressing in sealing elements deliberately introduced during assembly also remains relatively good. This is advantageous both during the assembly of the sealing element on the fluid cylinder and thereafter during the operation of the fluid cylinder. Moreover, the spatial crosslinking can also improve the temperature resistance of the material used for the sealing element. Moreover, the at least one sealing element of the fluid cylinder has an improved stress relaxation behavior and improved creep behavior. It also appears that the cross-linking considerably reduces the temperature dependence of this mechanical behavior of the sealing element. In this way, the temperature dependence of this material can be considerably improved, so that a fluid cylinder equipped with it has a largely temperature-independent density. Moreover, the wear behavior or the wear behavior in the sealing element and the fluid cylinder equipped therewith are improved.
    Overall, due to the additional crosslinking of the polyethylene used for the sealing cylinder for fluid cylinders, which may possibly be made of a non-cross-linked polyethylene, the fluid cylinder according to the invention has a relatively good density, which is maintained for a relatively long period of time. . This behavior is also relatively temperature tolerant.
    According to the invention, cross-linking takes place by means of gamma and / or electrode radiation or chemically.
    With cross-linking by radiation, the polyethylene is cross-linked by the use of electron beams and / or radiation in the gamma region. This has proven to be a particularly practical processing or manufacturing process. In this case, the radiation dose can be adjusted such that the cross-linked polyethylene used has a favorable relationship between the dimensional stability of the sealing element and reduced by reducing the mechanical properties of the molecular weight.
    Chemical crosslinking is based on the use of chemical substances or groups of substances. This crosslinking can be carried out, for example, by the use of peroxides, for example by the Engel process, by silanes or by azo compounds.
    Ideally, the cross-linking may take place prior to further processing steps, such as reduction or the like.
    According to the invention, the sealing element is made of PE-HD or PE-HMW of polyethylene.
    The polyethylene PE-HD is a semi-crystalline polyethylene with weakly branched polymer chains, therefore of high density and has an average molecular weight of up to 300 thousand g / mol. The advantage of the plastic is a very low coefficient of friction. It can be thermally deformed and welded. A considerable advantage lies in the simple processing by injection due to its low molecular weight.
    The polyethylene PE-HMW is a high molecular weight polyethylene with an average molar mass of about 500 thousand g / mol. It has a well-balanced mixture of stiffness, toughness and mechanical damping. It can also be thermally deformed and welded. Since the molecular weight is higher than that of PE-HD, the injection molding processing can be limited.
    When the sealing member is made from a polyethylene PE-LD or PE-LLD, the molecular weight of the polyethylene is low. PE-LLD is a linear low density polyethylene. The properties are similar to PE-HD because of the linear structure of the macromolecules, but it has the low density of PE-LD.
    If, as a possible advantageous embodiment, prior to further treatment of the sealing element, during or after networking is carried out to prevent or reduce oxidation, the required mechanical properties of the material such as the strength or resistance to material fatigue are retained. The free radicals during crosslinking can react with environmental oxygen, which leads to the formation of free radicals and a chain reaction. This oxidation process, which would result in an additional deterioration of mechanical properties, for example, can be prevented or reduced by heating the sealing element below the melting temperature after crosslinking. The residues are reduced but not completely eliminated, so that the mechanical properties are largely retained.
    For a particularly good, long-term sealing effect, the at least one sealing element can be substantially roof-shaped (referred to as chevron-shaped in English), i.e. with a cross-section. This means that each sealing element has an inner ring portion and an outer ring portion, which is approximately in an unloaded state
    Can be adjusted 90 ° to each other. This angle increases in a loaded state.
    To maintain the fluid cylinder particularly easily and / or locations, it can be advantageous if the at least one sealing element is arranged in or on the cylinder head. Alternatively, the one sealing element can be arranged in or on a cylinder head flange formed separately from the cylinder head. The cylinder head flange can also act as a sealing flange.
    For a particularly good fluid seal, it can be advantageous if a package of several sealing elements is provided. The package can for instance be formed by a plurality, namely for example two, three, four, five or more sealing elements are assembled in the axial direction of the fluid cylinder in a package.
    A further advantageous embodiment of the invention provides that the at least one sealing element is biased or biased in the axial direction of the fluid cylinder by a clamping ring. Alternatively or additionally, the at least one sealing element can be biased or biased in the axial direction of the fluid cylinder through at least one spacer disc. In this case, the biasing force can also be adjusted by a respective selection of the thickness or thickness of the spacer disk.
    The invention also relates to a method for manufacturing a fluid cylinder with a hollow cylinder body that is at least partially closed by a cylinder head attached thereto. A piston is movably guided within the cylinder body with a piston rod extending through the cylinder head to an outside of the fluid cylinder. For fluid sealing of the fluid cylinder, for example outwards, the fluid cylinder has at least one sealing element. Alternatively, the sealing element can also be attached to the piston and thus seal two pressure chambers of the cylinder against each other. According to the invention, the sealing element is made of a polyethylene, the polyethylene being additionally crosslinked by the use of gamma and / or electrode radiation or by the use of chemical substances. Crosslinking is understood to mean that the polyethylene is used spatially as a material, i.e. three-dimensionally in a network. The cross-linking or cross-linking is effected with the aid of a suitable processing method. The cross-linking by the use of electron beams and / or radiation in the gamma region, or, alternatively, by the use of chemical substances or groups of substances can be done, for example, by peroxides, for example by the Engel process, silanes or azo compounds.
    In the process, the production of the sealing element can preferably be made from polyethylene PE-HD, or polyethylene PE-HMW, PE-LD or PE-LLD.
    Further, in the method, a further process step can be provided, according to which the polyethylene after crosslinking is subjected to a stress relief process for reducing internal stresses.
    Additionally or alternatively, the method according to the invention can provide for free radicals in the polyethylene to be removed after crosslinking. As a result, the mechanical properties of the sealing element made of this material can be further improved.
    Ideally, the cross-linking may take place prior to further processing steps, such as reduction or the like.
    In the following, an advantageous embodiment of a fluid cylinder according to the invention will be explained in more detail with reference to a drawing. It shows:
    Figure 1 shows an embodiment of a fluid cylinder in a diagrammatic longitudinal section and
    Figure 2 shows a diagrammatic longitudinal section through a partial section of a fluid cylinder with a cylinder head flange and a package of sealing elements.
    Figure 1 shows an exemplary embodiment of a fluid cylinder 1 according to the invention in a longitudinal section roughly schematically represented. The fluid cylinder 1 is formed in this embodiment as a hydraulic working cylinder in the form of a differential cylinder.
    The fluid cylinder 1 comprises a hollow cylindrical body 2, which is closed at one end by a cylinder head 4, a separately formed cylinder head flange or sealing flange 6 at least partially (off). A piston 8 with a piston rod 10 is mounted within the hollow cylinder body 2 and is movably guided. Figure 1 shows that the piston rod 10 is guided by the cylinder head 4 and the cylinder head flange 6 and is stored there.
    For pressurizing the fluid cylinder 1, the hollow cylinder body 2 has two pressure medium connections 12 and 14, with which the pressure medium can be selectively arranged to move the piston 8 together with the piston rod 10 in the axial direction of the fluid cylinder 1.
    Figure 2 shows a partial cross-section of the fluid cylinder 1 and a schematic longitudinal section. In this representation it can be seen that the cylinder head flange 6 formed separately on the cylinder head 4 has a recess 16 which form both in the axial direction along the piston rod 10 and in the radial direction towards a space for receiving at least one sealing element 18. In In this embodiment, the sealing element 18 is composed of a plurality, namely seven separate elements that are combined into a package of sealing elements. The number of sealing elements 18 disposed between the cylinder head flange 6 and the piston rod 10. As a result, the plurality of sealing elements 18 lie with a radial inner fluid sealing against the piston rod to prevent the escape of pressure medium from the annular space of the hollow cylinder body 2. It can also be seen that the cross-section of each sealing member 18 is chevron-shaped. Due to this configuration, the plurality of sealing parts 18 are spread against the piston rod 10.
    For the axial bias of the number of sealing elements 18, the fluid cylinder 1 also has a clamping ring 20 which presses on the number of sealing elements 18 from the axial direction. A spacer disk 22 is arranged between the clamping ring 20 and the plurality of sealing elements 18. Due to this bias, the spreading action of the sealing elements 18 is again increased.
    In this example each sealing element 18 consists of a (spatial or three-dimensional) cross-linked polyethylene PE-HD, which is characterized by its favorable mechanical properties for this purpose. In particular, the sealing elements 18 made of this cross-linked material have a relatively high dimensional stability and reduced stress relaxation. In this embodiment, polyethylene PE-HD is cross-linked by means of gamma and / or electrode radiation. Thanks to the crosslinking of the polyethylene PEHD used for the sealing elements 18 and the resulting mold durability, the bias applied to the sealing elements 18 is maintained for a relatively long period of time.
    Starting from the illustrated embodiment, the fluid cylinder 1 of the invention and the manufacturing method can be modified in many ways. It is thus conceivable that the cross-linking of the PE-HD polyethylene for the at least one sealing element 18 takes place not by means of gamma radiation and / or radiation electrode, but by the use of chemical substances or groups of substances. Another modification may be that the polyethylene PE-HMW polyethylene PE-LD or polyethylene PE-LLD is used as raw material for the production of the sealing element.
    Described is a fluid cylinder with a hollow cylinder body that is at least partially closed by a cylinder head attached thereto. A piston is guided inside the hollow cylinder body and has a piston rod which extends through the cylinder head to an outside of the fluid cylinder. Outwardly, the fluid cylinder is smoothly closed by at least one sealing element. According to the invention, the at least one sealing element consists of a polyethylene crosslinked by means of gamma and / or electrode radiation or chemically.
    List of reference numbers
    4
    12, 14
    16
    Fluid cylinder
    Hollow cylindrical body
    Cylinder head
    Cylinder head flange
    Piston
    Piston rod
    Pressure medium connections
    Cutout
    Sealing element (s)
    Clamp ring
    Spacer disc
    权利要求:
    Claims (13)
    [1]
    Conclusions
    A fluid cylinder (1) with a hollow cylindrical body (2) which is at least partially closed by a cylinder head (4) attached thereto, a piston (8) which is fed on an inside of the hollow cylindrical body (2) and which has a piston rod (10) which extends through the cylinder head (4) to at least one outside of the fluid cylinder (1) and with at least one sealing element (18), which fluidly seals a working space of the fluid cylinder (1), characterized in that the at least one sealing element (18) consists of a polyethylene which is radiation or chemically crosslinked by means of gamma and / or electrode.
    [2]
    A fluid cylinder according to claim 1, characterized in that the sealing element consists of a polyethylene PE-HD or PE-HMW.
    [3]
    3. Fluid cylinder according to claim 1, characterized in that the sealing element consists of a polyethylene PE-LD or PE-LLD.
    [4]
    A fluid cylinder according to claim 1, 2 or 3, characterized in that the sealing element is thermally treated.
    [5]
    Fluid cylinder according to one of the preceding claims, characterized in that the at least one sealing element (18) is chevron-shaped.
    [6]
    Fluid cylinder according to one of the preceding claims, characterized in that the at least one sealing element (18) in or on the cylinder head (4), or in or on a cylinder head flange (6) formed separately from the cylinder head (4) ) is installed.
    [7]
    Fluid cylinder according to one of the preceding claims, characterized in that a package is provided with a plurality of sealing elements (18).
    [8]
    Fluid cylinder according to one of the preceding claims, characterized in that the at least one sealing element (18) in the axial direction of the fluid cylinder (1) passes through a clamping ring (20) and / or at least one spacer disc (22) to be tensioned or prestressed.
    [9]
    A method for manufacturing a fluid cylinder (1) which has a hollow cylindrical body (2) which is at least partially closed by a cylinder head (4) attached thereto, and on an inner side of the hollow cylindrical body (2) guided piston (8) with a piston rod (10), which extends through the cylinder head (4) to at least one outside of the fluid cylinder (1) and at least one sealing element (18) fluidizing the working space of the fluid cylinder (1) sealed with the feature that the at least one sealing element (18) is made from a polyethylene that is actually crosslinked by the use of gamma and / or electrode radiation or by the use of chemical substances.
    [10]
    Method according to claim 9, characterized in that the sealing element is made from a polyethylene PE-HD or PE-HMW.
    [11]
    A method according to claim 9, characterized in that the sealing element is made from a polyethylene PE-LD or PE-LLD.
    [12]
    A method according to claim 9, 10 or 11, characterized in that, after crosslinking, the polyethylene is subjected to a stress relief process for reducing internal stresses.
    [13]
    Method according to one of claims 9 to 11, characterized in that free radicals are removed in the polyethylene after cross-linking.
    1/1
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