• 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:

    公开号:NL2015813A
    申请号:NL2015813
    申请日:2015-11-19
    公开日:2016-09-13
    发明作者:Caspers Leo；Dupuis Leo
    申请人:Bosch Gmbh Robert；
    IPC主号:
    专利说明:

    Title: Liquid cylinder with an improved sealing element and a method for manufacturing such a cylinder.
    DESCRIPTION
    The invention relates to a liquid cylinder according to the preamble of claim 1. The invention further relates to a method for manufacturing a liquid cylinder according to the preamble of claim 8.
    Liquid cylinders in the form of hydraulic cylinders or pneumatic cylinders for various technical applications are already known in practice. These liquid cylinders are also referred to as hydraulic or pneumatically operating cylinders.
    Particularly in the case of hydraulically operating fluid cylinders, there is generally a desire to shape it, if possible, in a liquid-tight manner, so that the pressure means used for the use of the fluid cylinder, for example a hydraulic oil, cannot escape through gaps and leakages caused thereby. For this purpose sealing elements are usually used which are made of plastic and / or rubber and which in particular seal the part of the liquid cylinder where a piston rod is discharged from a hollow cylindrical body. This part is often located in or on a cylinder head of the liquid cylinder.
    Furthermore, it is known from practice that ultra high molecular weight polyethylene (also referred to as UHMWPE or UHMW-PE) is relatively highly suitable as a raw material for use in sealing elements for liquid cylinders. For example, ultra high molecular weight polyethylene has relatively good chemical and mechanical properties: it is resistant to mineral oils and hydraulic oils. In addition, ultra-high molecular weight polyethylene has favorable frictional properties, making it relatively well suited as a raw material for passing through a piston rod of a liquid cylinder.
    Nevertheless, with such sealing elements due to aging during the service life of the liquid cylinder, various, partly temperature-dependent, mechanical signs of wear occur, such as, for example, creeping and stress reduction. As a result, such a sealing element deforms or loses its bias. It has come to light that these signs of wear and tear work out in such a way that an initially largely sealed liquid cylinder starts to show increasing leaks over time, through which the pressure medium can escape. This requires regular maintenance work on the fluid cylinder to renew the sealing elements and to ensure the fluid tightness of the fluid cylinder.
    It is therefore an object of the invention to provide a liquid cylinder which, by means of a constructionally as simple as possible, provides an improved shelf life or longer service life with regard to the seal.
    This object is achieved by a liquid cylinder with the features according to claim 1 or by a method for manufacturing a liquid cylinder with the features of claim 8.
    Preferred embodiments of the liquid cylinder according to the invention are given in the dependent claims.
    The liquid cylinder according to the invention is provided with a hollow cylindrical body, which is at least partially closed off by a cylinder head coupled thereto or mounted thereon. A piston provided with a piston rod is movably arranged on the inside of the hollow cylindrical body, the piston rod extending at least to an outside of the liquid cylinder. For the liquid-tight sealing of the liquid cylinder, for example towards the outside, the liquid cylinder is provided with at least one sealing element which can for instance be arranged near the piston rod, to prevent liquid escaping or escaping via the piston rod. Alternatively, the sealing element can also be arranged on the piston and be in engagement with the hollow cylindrical body. According to the invention, the at least one sealing element consists of cross-linked ultra-high molecular weight polyethylene. This means that the at least one sealing element is made from an ultra-high-molecular-weight polyethylene, this raw material being additionally cross-linked.
    In this context, by crosslinking or crosslinking of the ultra-high molecular weight polyethylene (also known as UHMWPE or UHMW-PE), it is understood that the raw material of the sealing element is spatially, i.e. three-dimensionally, crosslinked before it becomes a sealing element is processed and / or the sealing element is installed or used in the liquid cylinder. This results in additional cross-connections (cross-links) between the polyethylene chains. The additional cross-linking or the additional cross-linking of the ultra-high-molecular-weight polyethylene used for the sealing element has the advantage that the sealing element is elastically deformable in some cases, but nevertheless a relatively high degree of shape retention or shape resistance, as well as a relatively high degree of retention of dimensions, respectively. dimensional stability. Pre-tensioning intentionally applied to the sealing element during assembly is also relatively well preserved. This is an advantage both during the mounting of the sealing element in the liquid cylinder and also afterwards, during operation of the liquid cylinder.
    Moreover, the spatial crosslinking can also improve the temperature resistance of the raw material used for the sealing element, as well as increase the impact resistance and the tear stress resistance. Moreover, the at least one sealing element of the liquid cylinder has improved anti-relaxation properties as well as improved creep properties. It has further been found that cross-linking clearly reduces the temperature dependence of the mechanical behavior of the sealing element. In this way the temperature dependence of the raw material is significantly improved, so that a liquid cylinder equipped with this raw material has a far-reaching temperature-independent seal. In addition, the wear behavior or wear behavior of the sealing element and the liquid cylinder provided with it are also improved.
    All in all, by additionally cross-linking the ultra-high-molecular-weight polyethylene used in the sealing element, the liquid cylinder according to the invention also has a relatively good seal, which in some cases is made from non-cross-linked ultra-high-molecular-weight polyethylene. relatively long time. This behavior is also relatively temperature tolerant.
    In a particularly advantageous embodiment of the invention, the at least one sealing element is cross-linked by means of gamma and / or electron radiation. This means that the ultra-high-molecular-weight polyethylene is cross-linked by the use of electron radiation and / or radiation in the gamma range. This embodiment has proved to be a particularly practical method of processing or production. The amount of radiation is thereby adjusted so that the crosslinked ultra-high molecular weight polyethylene used has a favorable ratio between the shape resistance of the sealing element and the mechanical properties reduced by the reduction of the molecular weight.
    In a further advantageous embodiment, the at least one sealing element is chemically cross-linked, i.e. by the use of chemical substances or groups of substances. This cross-linking by the use of chemical substances or groups of substances can be effected, for example, by the use of peroxides, for example on the basis of the Engel method, of silanes or of azo compounds.
    Ideally, crosslinking can take place prior to further processing steps, such as, for example, reduction or the like.
    If in a possible further embodiment an additional treatment of the sealing element to prevent or reduce oxidation takes place before, during or after cross-linking, the necessary mechanical properties of the material, such as the strength and resistance to material fatigue, are retained. The free radicals formed during crosslinking can react with ambient oxygen, which leads to new radical bonding and thus to a chain reaction. This oxidation, which can lead to an additional deterioration of the mechanical properties, can be prevented or reduced by, for example, heating the sealing element after cross-linking under the melting temperature. As a result, the radicals are reduced, but not completely removed, so that the mechanical properties are preserved as much as possible.
    For a particularly good, long-acting sealing action, the at least one sealing element can be provided with a substantially roof-cuff-shaped shape (referred to in English as a chevron-shaped), i.e. with a roof-cuff-shaped cross-section. This means that each sealing element has an inner ring part region and an outer ring part region, the part regions in an unloaded state being at an angle of approximately 90 ° with respect to each other. This angle increases in a loaded state.
    In order to be able to maintain and / or assemble the liquid cylinder in a simple manner, it can be advantageous if the at least one sealing element is connected in or to the cylinder head. Alternatively, the at least one sealing element can be connected to a separate cylinder head flange formed in or on the cylinder head. The cylinder head flange can simultaneously function as a sealing flange.
    For a particularly good liquid-tight seal, it can be advantageous if a package is provided with several sealing elements. The package may, for example, be constructed such that a plurality, namely, for example, two, three, four, five or more sealing elements in the axial direction of the liquid cylinder are placed together to form a package.
    In a further embodiment according to the invention, the at least one sealing element can be biased or prestressed in the axial direction of the liquid cylinder by means of a clamping ring. Alternatively or additionally, the at least one sealing element can be biased in the axial direction or be biased by at least one spacer ring. The biasing force can thereby also be adjusted by selecting the thickness or the strength of the spacer ring.
    The invention further comprises a method for manufacturing a liquid cylinder provided with a hollow cylindrical body which is at least partially closed off by a cylinder head arranged thereon.
    A piston provided with a piston rod is movably arranged on the inside of the hollow cylindrical body, the piston rod extending through the cylinder head to an outside of the liquid cylinder. For the liquid-tight sealing of the liquid cylinder, such as, for example, outwards, the liquid cylinder is provided with at least one sealing element. Alternatively, the sealing element can also be arranged on the piston and thereby even seal two pressure spaces of the cylinder. According to the invention, the sealing element is made from ultra-high-molecular-weight polyethylene, the ultra-high-molecular-weight polyethylene being additionally crosslinked. Cross-linking is understood here to mean that the ultra-high-molecular-weight polyethylene used as raw material is spatially, i.e. three-dimensionally, cross-linked. This cross-linking or cross-linking is carried out by means of an appropriate processing method.
    A particularly advantageous embodiment of the method comprises that the crosslinking is carried out by the use of gamma and / or electron radiation or by the use of chemical substances. This means that the ultra high molecular weight polyethylene is crosslinked by the use of electron beams and / or by radiation in the gamma range, or, alternatively, by the use of chemical substances or groups of chemical substances. Peroxide can be used for this purpose, for example by means of the Engel method, silanes or azo compounds.
    Further, in the process, an additional process step can be performed, wherein after crosslinking, a stress reduction process is performed on the ultra-high molecular weight polyethylene to reduce the inner stresses.
    Additionally or alternatively, the method of the invention may include removing free radicals after the ultra high molecular weight polyethylene is crosslinked. This has the advantage that the mechanical properties of the sealing element formed from this raw material further improve.
    Ideally, crosslinking can be performed prior to further processing steps, such as, for example, crushing or the like.
    The liquid cylinder according to the invention is explained in more detail below with reference to an example of an advantageous embodiment.
    SHORT FIGURE DESCRIPTION
    Figure 1 shows a schematic longitudinal section of an example of an embodiment of a liquid cylinder according to the invention; and
    Figure 2 shows a schematic longitudinal section of a partial cut of a liquid cylinder, in which a cylinder head flange and a package of sealing elements are shown.
    DETAILED DESCRIPTION
    Figure 1 shows a rough schematic longitudinal section of an example of an embodiment of a liquid cylinder 1 according to the invention. In the embodiment of this example, the liquid cylinder 1 is designed as a hydraulic working cylinder in the form of a differential cylinder.
    The liquid cylinder 1 is provided with a hollow cylindrical body 2 which is at least partially closed off at the rear by a cylinder head 4 with a separately arranged cylinder head flange or sealing flange 6. Inside the hollow cylindrical body 2 is a movable piston 8 with piston rod 10 arranged. Figure 1 shows that the piston rod 10 extends through the cylinder head 4 and the cylinder head flange 6 and is mounted therein.
    For pressurizing the pressure medium of the liquid cylinder 1, the hollow cylindrical body 2 is provided with two pressure medium connections 12, 14, the piston 8 with piston rod 10 being movable in the axial direction of the liquid cylinder 1 by alternating pressure.
    Figure 2 shows a partial cut-out of a schematic longitudinal section of a liquid cylinder 1. This figure shows that the cylinder head flange 6 arranged separately on the cylinder head 4 comprises a recess 16 which extends both axially along the piston rod 10 and also in radial extends so that a space for receiving at least one sealing element 18 is formed. In the embodiment shown in this example, the sealing element 18 consists of a plurality, namely seven single elements, which are combined into a package of sealing elements. The plurality of sealing elements 18 is disposed between the cylinder head flange 6 and the piston rod 10. As a result, the plurality of sealing elements 18 with a radial inner side engage fluid-tightly on the piston rod 10, thereby preventing the pressure medium from escaping from the annular space of the hollow cylindrical body 2. It is also visible that a cross-section of each sealing element 18 is of roof-shaped design.
    Due to this configuration, the plurality of sealing elements 18 are pressed against the piston rod 10.
    To realize an axial bias of the plurality of sealing elements 18, the liquid cylinder 1 is further provided with a clamping ring 20 which presses the plurality of sealing elements 18 in the axial direction. A spacer ring 22 is arranged between the clamping ring 20 and the plurality of sealing elements 18. Due to this bias, the pressure effect of the sealing elements 18 is further increased.
    Each sealing element 18 in the example shown consists of a (spatially or three-dimensional) cross-linked ultra-high-molecular-weight polyethylene (also referred to as UHMWPE or UHMW-PE), which is very suitable for this application due to its favorable mechanical properties. In particular, the sealing elements 18 made from this cross-linked raw material have a relatively high degree of shape retention and a reduced degree of stress reduction. In the example shown, the ultra-high molecular weight polyethylene is crosslinked by means of gamma and / or electron radiation. Due to the crosslinking of the ultra-high molecular weight polyethylene used for the sealing element 18 and the degree of shape retained thereby achieved, the bias applied to the sealing element 18 is retained for a relatively long period of time.
    Starting from the exemplary embodiment shown, liquid cylinder 1 according to the invention and the method according to the invention can be carried out in various ways. For example, it is conceivable that the ultra high molecular weight polyethylene of the at least one sealing element 18 is crosslinked not by gamma and / or electron radiation, but by the use of chemical substances or groups of chemical substances.
    A liquid cylinder with a hollow cylindrical body is disclosed, which is at least partially closed off by a cylinder head connected thereto. A piston with a piston rod is arranged in the hollow cylindrical body, the piston rod extending through the cylinder head at least to an outside of the liquid cylinder. To the outside, the liquid cylinder is sealed in a liquid-tight manner by at least one sealing element.
    According to the invention, the at least one sealing element consists of a cross-linked ultra-high-molecular-weight polyethylene.
    LEGENDA 1 - liquid cylinder 2 - hollow cylindrical body 4 - cylinder head 6 - cylinder head flange 8 - piston 10 - piston rod 12, 14 - pressure medium connection 16 - recess 18 - sealing element (s) 20 - clamping ring 22 - spacer ring
    权利要求:
    Claims (12)
    [1]
    Liquid cylinder (2) provided with a hollow cylindrical body (2) which is at least partially closed off by a cylinder head (4) arranged thereon, a piston (8) inserted in the hollow cylindrical body and provided with a piston rod ( 10) which extends through the cylinder head (4) at least to an outside of the liquid cylinder (1), and with at least one sealing element (18) that seals a working space of the liquid cylinder (1) in a liquid-tight manner, characterized in that the at least one sealing element (18) consists of a cross-linked ultra-high molecular weight polyethylene.
    [2]
    Liquid cylinder according to claim 1, characterized in that the at least one sealing element (18) is cross-linked by means of gamma and / or electron radiation.
    [3]
    Liquid cylinder according to claim 1, characterized in that the at least one sealing element (18) is chemically cross-linked.
    [4]
    Liquid cylinder according to claim 1, 2 or 3, characterized in that the sealing element is thermally treated.
    [5]
    Liquid cylinder according to one of the preceding claims, characterized in that the at least one sealing element (18) is of roof-shaped design.
    [6]
    Liquid 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 separate cylinder head flange (6) formed on the cylinder head (4) is connected.
    [7]
    Liquid cylinder according to one of the preceding claims, characterized in that a package is provided with a plurality of sealing elements (18).
    [8]
    Liquid cylinder according to one of the preceding claims, characterized in that the at least one sealing element (18) can be pre-stressed or prestressed in the axial direction of the liquid cylinder (1) by means of a clamping ring (20) and / or at least one spacer ring (22) .
    [9]
    Method for manufacturing a liquid cylinder (1) with a hollow cylindrical body (2) which is at least partially closed off by a cylinder head (4) arranged thereon and which is provided with a hollow cylindrical body (2) inserted piston (8) with a piston rod (10) extending through the cylinder head (4) at least to an outside of the liquid cylinder (1), and which is provided with at least one sealing element (18) that has a working space of the liquid cylinder (1) liquid-tight seal, characterized in that the at least one sealing element (18) is made from ultra-high-molecular-weight polyethylene, which is additionally crosslinked.
    [10]
    Method according to claim 9, characterized in that the crosslinking is carried out by the use of gamma and / or electron radiation or by the use of chemical substances.
    [11]
    A method according to claim 9 or 10, characterized in that after crosslinking the ultra high molecular weight polyethylene, a stress reduction treatment for reducing internal stresses is carried out.
    [12]
    A method according to any one of claims 9 to 11, characterized in that free radicals are removed from the ultra high molecular weight polyethylene after crosslinking.
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    同族专利:
    公开号 | 公开日
    NL2015813B1|2018-01-12|
    DE102015209750A1|2016-05-25|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    NL2020570A|2017-03-22|2018-09-28|Bosch Gmbh Robert|Fluid cylinder with improved sealing element and manufacturing method for it|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    DE102014223800|2014-11-21|
    DE102015209750.1A|DE102015209750A1|2014-11-21|2015-05-28|Fluid cylinder with improved sealing element and manufacturing method therefor|
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