EP4259942A1 - Unité piston d'un cylindre de travail - Google Patents

Unité piston d'un cylindre de travail

Info

Publication number
EP4259942A1
EP4259942A1 EP21844182.2A EP21844182A EP4259942A1 EP 4259942 A1 EP4259942 A1 EP 4259942A1 EP 21844182 A EP21844182 A EP 21844182A EP 4259942 A1 EP4259942 A1 EP 4259942A1
Authority
EP
European Patent Office
Prior art keywords
piston
thread
piston rod
working cylinder
internal thread
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
EP21844182.2A
Other languages
German (de)
English (en)
Inventor
Josef Bueter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Buemach Engineering International BV
Original Assignee
Buemach Engineering International BV
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
Application filed by Buemach Engineering International BV filed Critical Buemach Engineering International BV
Publication of EP4259942A1 publication Critical patent/EP4259942A1/fr
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1423—Component parts; Constructional details
    • F15B15/1447—Pistons; Piston to piston rod assemblies
    • F15B15/1452—Piston sealings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
    • F15B15/08—Characterised by the construction of the motor unit
    • F15B15/14—Characterised by the construction of the motor unit of the straight-cylinder type
    • F15B15/1423—Component parts; Constructional details
    • F15B15/1447—Pistons; Piston to piston rod assemblies
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J1/00—Pistons; Trunk pistons; Plungers
    • F16J1/10—Connection to driving members
    • F16J1/12—Connection to driving members with piston-rods, e.g. rigid connections
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16J—PISTONS; CYLINDERS; SEALINGS
    • F16J7/00—Piston-rods

Definitions

  • the invention relates to a piston unit of a working cylinder.
  • the object of the invention is to produce a simple, spatially compact and at the same time operationally reliable connection between the piston and the piston rod, which should also be easy to manufacture and provide a reliable seal between the working spaces separated from the piston.
  • the piston unit of a working cylinder generically has a piston rod and a piston. Piston rod and piston are also collectively referred to below as the coupling partners.
  • the piston rod has an external thread on a piston-side coupling section.
  • the piston is provided with an axial bore in which the piston rod is received.
  • the axial bore has an internal thread.
  • the external thread of the piston rod and the internal thread of the piston form a common thread section.
  • the common thread section preferably extends essentially over the entire length of the external thread and the internal thread.
  • the external thread and the internal thread have a conicity.
  • the diameter of the external wind is larger at its proximal end than at its distal end.
  • the conicity of the external thread and internal thread match and the conicity have a conicity angle alpha of 0.3 to 5 degrees relative to a main longitudinal axis of the piston rod.
  • the external thread and the internal thread are also collectively referred to below as the thread partners.
  • the external thread and the internal thread have a matching thread geometry. Due to the matching thread geometry, the thread partners are designed in such a way that in a coupling end position in the common thread section they rest against one another without any gaps and form a sealing plane. This form-fit connection of the two thread partners causes a largely homogeneous surface pressure on the thread flanks and a large-area form fit.
  • the external threads and internal threads exhibit elastic deformation in the threaded portion in the coupling end position.
  • the elastic deformation is within the elasticity limits of the piston rod and piston.
  • the elastic deformation is formed by means of a surface pressure through a tightening torque.
  • the axial positional relationship of the coupling partners is adjusted towards one another by means of a tightening torque by means of the threaded partners, whereby an oversize of the diameter of the piston rod relative to the piston is formed in the common threaded section due to the conicity according to the invention by means of a wedge effect. This causes the press fit and the elastic deformation of the thread partners.
  • the elastic deformation is present both without and with the application of pressure to a pressure medium in the working cylinder within the limits of elasticity.
  • the piston rod and the piston are fixed radially and axially with respect to one another in the coupling end position according to the invention.
  • the piston is thus fixed exactly on the piston rod.
  • the solution according to the invention has in particular the advantages listed below. The following was surprisingly found. Due to the radial pressure applied between the thread partners by means of the torque, a concentric radial elastic deformation is primarily achieved on the piston rod and an eccentric radial elastic deformation on the piston. In addition to the primary radial elastic deformation, a small secondary axial elastic deformation is also achieved on the piston rod and on the piston, these advantageously being directed in opposite directions. It is an axial elastic elongation of the piston rod and axial elastic compression of the piston. In this way, the external thread and the internal thread in the proximal section of the common threaded section and in the distal section of the common threaded section are clamped axially in opposite directions to one another.
  • a neutral zone is formed in relation to axial bracing.
  • the opposing axial elastic bracing advantageously ensures that deformation remains within the elastic limits not only when an axial load is applied by the operating forces when used as intended, but also because of the elastic pretension even without a load application. In addition, this applies advantageously regardless of the direction of the axial application of force.
  • the piston is advantageously fixed radially and axially on the piston rod in all load states without play. In the event of a reversal of force or movement of the piston unit, axial migration of the piston on the piston rod is reliably prevented.
  • the surface pressure on the thread flanks is maintained independently of the operating state due to the elastic prestressing and the form fit of the thread flanks, so that the piston is prevented from turning loose.
  • no further securing element is required to prevent loosening.
  • sealing is advantageously achieved by the thread geometry via the freedom of space between the external thread and the internal thread.
  • the effects of a labyrinth seal are advantageously used here.
  • the surface tension in the case of a fluidic pressure medium also prevents a transfer of pressure medium via the common threaded section.
  • the piston is also very compact in its design and thus provides advantageous space and material savings.
  • the piston unit according to the invention is advantageously easy to produce.
  • the two joining partners can be better positioned relative to each other at the beginning of the joining process, since the individual thread flanks already fit into one another and find each other.
  • the thread can also be easily screwed on until the form closure.
  • piston unit according to the invention can be a piston unit for different types of working cylinders such as, for example, but not conclusively act for differential working cylinders, tension cylinders, damping cylinders or pneumatic cylinders.
  • the conicity has a conicity angle alpha of 0.5 to 1.5 degrees.
  • the taper is present over the entire axial length of the thread.
  • the mean thread diameter is conical over the entire axial length. It has been found that the geometries present at this conicity angle provide a particularly advantageous ratio of the described radial and axial elastic deformations according to the invention.
  • the thread flanks have an angle of inclination beta of 55 to 100 degrees.
  • the thread flank shape is provided in the transition area from the acute to the obtuse angle. Sufficient lateral guidance is achieved when screwing in, so that the two parts to be joined do not jam together.
  • the thread flank is sufficiently stable to absorb the surface pressure and the axial load.
  • a sealing body is arranged in the threaded section in the internally threaded area of the piston.
  • a radially inner annular surface of the seal body has a seal body threaded portion that forms an axial portion of the internally threaded portion of the piston.
  • a sealing body is preferably used for this purpose in a recess in the piston.
  • This can preferably consist of an elastic material such as plastic or rubber. It can be used as a dimensionally stable body or injected as a hardening, liquid component.
  • the external thread of the piston rod cuts during joining automatically into the sealing body, so that the sealing body thread section is formed on its radial inner annular surface.
  • the sealing body already has the sealing body thread section before joining.
  • the sealing body can preferably be mounted without the sealing body thread section, so that the internal thread of the piston and at the same time the sealing body thread section of the sealing body can then be produced in a common operation.
  • the conicity of the external thread of the piston rod and the conicity of the sealing body thread section advantageously work together.
  • the external thread and the sealing body section are radially pressed against one another and seal against one another.
  • FIG. 1 Sectional view of the working cylinder with piston unit
  • FIG. 2 Detailed view of the threaded section as a section
  • FIG. 3 Detailed view of the threaded section as a section with the sealing body explained in more detail.
  • the use of the reference symbols in the figures and in the associated sections of description is consistent below, even if not all figures are provided with all the reference symbols.
  • FIG. 1 shows the working cylinder 1 in a sectional view.
  • the exemplary embodiment involves a double-acting hydraulic cylinder as a differential working cylinder.
  • the piston unit 2 is composed of the piston rod 3 and the piston 4.
  • a conical external thread 5 is located on the piston rod 3 at a piston-side end.
  • the piston 4 is screwed onto this by means of the internal thread 6.
  • the internal thread also has a conicity.
  • the taper angle a of both the external thread 5 and the internal thread 6 is 1 degree.
  • the external thread 5 and the internal thread 6 engage with one another in a common threaded section 7 .
  • FIG. 2 shows the detailed view of a section of the common threaded section 7.
  • the thread shape of the external thread 5 of the piston rod 3 has the same shape as the internal thread 6, so that they rest against one another without any gaps.
  • the angle of inclination ß here is 90 degrees and the angle of conicity a is 0.75 degrees.
  • both threads 5, 6 formed by the mean thread diameter is conical over the axial thread length. Due to the conical shape of both threads 5, 6, the piston 4 can be screwed onto the piston rod 3 up to a specific position. This results in a form fit of the thread flanks, which at the same time has a fluid-sealing effect.
  • the screw-in path is continued until a radial concentric elastic deformation of the piston rod 3 and a radial eccentric elastic deformation of the piston 4 are produced.
  • an axial elastic deformation of the piston rod 3 as an elongation and an axial elastic Table deformation of the piston 4 causes compression.
  • the axial elastic deformations are represented by the vertical arrows. The diagonal arrows pointing at one another indicate the additional surface pressure on the flanks of the thread and thus the elastic axial tension between the piston rod 3 and the piston 4 .
  • FIGS. 1 and 2 show a detailed view of part of the common threaded section 7 in an embodiment with a sealing body 8.
  • the basic structure corresponds to FIGS. 1 and 2, so that reference is made to these figures and the associated sections of the description.
  • FIG. 3 shows an exemplary embodiment in a further variant of the geometry of the external thread 5 and the internal thread 6.
  • the thread crests and thread sinks are flattened here and form a trapezoidal thread.
  • a form-fitting and gap-free thread engagement is also achieved here.
  • a sealing body 8 is inserted into a recess in the inner lateral surface of the axial bore in the piston 4 .
  • This consists of an elastomeric material.
  • the external thread of the piston rod 3 lies in a corresponding press fit on that of the sealing body 8 . A tight form fit is created.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Abstract

L'invention concerne une unité piston (2) d'un cylindre de travail (1). Selon l'invention : - une tige de piston (3) présente un filetage extérieur (5) sur une partie de couplage côté piston ; - un piston (4) présente un alésage axial qui comprend un filetage intérieur (6) et dans lequel la tige de piston (3) est reçue ; - le filetage extérieur (5) et le filetage intérieur (6) forment une partie filetée commune (7) ; - le filetage extérieur (5) et le filetage intérieur (6) ont une conicité complémentaire et une géométrie de filetage complémentaire ; - la conicité a un angle de conicité alpha de 0,3 à 5 degrés ; - le filetage extérieur (5) et le filetage intérieur (6) viennent buter l'un contre l'autre dans une position d'extrémité de couplage dans la partie filetée dans un espace et forment un plan d'étanchéité ; - le filetage extérieur (5) et le filetage intérieur (6) ont, dans la partie filetée dans la position d'extrémité de couplage, une déformation élastique à l'intérieur de la limite élastique de la tige de piston (3) et du piston (4) ; - la déformation élastique est provoquée par une pression de surface via un couple de serrage ; - la tige de piston (3) et le piston (4) sont radialement et axialement fixes l'un par rapport à l'autre sans jeu dans la position d'extrémité de couplage au moyen de la déformation élastique, et - la déformation élastique est à l'intérieur de la limite élastique à la fois avec et sans application de pression par un milieu de pression dans le cylindre de travail (1).
EP21844182.2A 2020-12-11 2021-12-07 Unité piston d'un cylindre de travail Pending EP4259942A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE202020005143.8U DE202020005143U1 (de) 2020-12-11 2020-12-11 Kolbeneinheit eines Arbeitszylinders
PCT/DE2021/000192 WO2022122063A1 (fr) 2020-12-11 2021-12-07 Unité piston d'un cylindre de travail

Publications (1)

Publication Number Publication Date
EP4259942A1 true EP4259942A1 (fr) 2023-10-18

Family

ID=79686911

Family Applications (1)

Application Number Title Priority Date Filing Date
EP21844182.2A Pending EP4259942A1 (fr) 2020-12-11 2021-12-07 Unité piston d'un cylindre de travail

Country Status (5)

Country Link
US (1) US20240035496A1 (fr)
EP (1) EP4259942A1 (fr)
CN (1) CN116601410A (fr)
DE (2) DE202020005143U1 (fr)
WO (1) WO2022122063A1 (fr)

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB890156A (en) * 1958-11-11 1962-02-28 Maquinaria Petrolifera S A Piston, and piston and rod assembly for reciprocating pumps
US4072434A (en) 1975-12-03 1978-02-07 Homuth Kenneth C Hydraulic cylinder with concentrically maintained piston and rod
FR2755739B1 (fr) 1996-11-12 1998-12-18 Chapel Dispositif pour etancher les deux chambres d'un verin, separees par un piston, tout en empechant celui-ci de se debloquer
US9200708B2 (en) 2012-02-29 2015-12-01 Caterpillar Inc. Piston retention apparatus and method
DE202012008999U1 (de) 2012-09-19 2014-01-15 Bümach Engineering International B.V. Kolbeneinheit eines Arbeitszylinders
DE202016007691U1 (de) * 2016-12-21 2018-03-22 Bümach Engineering International B.V. Schraubarbeitszylinder

Also Published As

Publication number Publication date
WO2022122063A1 (fr) 2022-06-16
US20240035496A1 (en) 2024-02-01
DE112021006397A5 (de) 2023-09-28
CN116601410A (zh) 2023-08-15
DE202020005143U1 (de) 2022-03-15

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