EP2489885A1 - Piston for a work cylinder - Google Patents

Abstract

The piston (1) has piston elements (23a,23b) that are made up of plastic material. The locking devices (24a,24b) are provided between piston seal portions (36a,36b). The core portion (25) of the piston (13) is latched by latching device. The latch device is overlapped with core portion such that the core portion is extended along peripheral outer wall (42) of the piston.

Description

The invention relates to a piston for a working cylinder, with two at least partially made of plastic material piston elements, of which at least one radially outwardly disposed piston seal and arranged from one another axially opposite sides by means of a latching device arranged on each of them independently of one another between them Core body of the piston are coaxially latched so that they are held together axially by the core body, wherein the latching means engage over the core body at its radially outwardly facing outer periphery.

One from the EP 1 899 611 B1 known piston of this type has two cup-shaped piston elements, which between them include a partly for stabilization and partly for Positionsab-question serving metallic core structure. The core structure is designed in several parts and has a central core body surrounded by a ring magnet, to which the two piston elements are latched independently of one another from opposite sides by means of latching devices arranged on them. The latching device, which has a plurality of latching hooks, intervenes between the core body and the ring magnet. Radially outside the latching device, the two piston elements define together a receiving chamber, the Ring magnet receives and is bounded radially outwardly by a peripheral outer wall of the piston. The peripheral outer wall may simultaneously form a guide surface for the linear guide of the piston when the same is arranged for its intended use in the cylinder housing of a working cylinder.

In the known piston, it has proven to be problematic to accommodate the latching devices in the narrow space between the piston body and the outer ring magnet. The available space is tight, because the core body should have the largest possible outside diameter to give the piston a high stability. In the known case, it is ensured that on the periphery of the piston body in the circumferential direction distributed recesses are introduced into which the latching devices can engage with their latching hooks. However, this measure requires a not inconsiderable constructive and therefore also financial expense.

From the EP 0 036 538 A1 a piston for a working cylinder is known in which two piston elements, including a ring magnet are locked together directly. The markable as the core body ring magnet does not participate in the locking connection.

One from the DE 20 2005 013 185 U1 known piston has two piston elements which are locked together by means of acting as a guide band additional component and thereby fix a ring magnet between them.

The invention has for its object to provide a multi-part piston whose components are simple and inexpensive can be produced and which can be easily assembled.

To solve this problem, in a piston having the features cited above, the latching means of the two piston elements are designed and arranged such that together they form a peripheral outer wall of the piston extending around the core body.

In this way, a core structure formed by the core body or containing the core body of the piston, which may serve different purposes depending on the embodiment, overlapped by the latching means of the two piston elements radially outward. The latching devices can therefore be designed optimally and, in particular with regard to the core body, there is no need for a complex design in order to ensure the accommodation of the latching devices. For example, it is possible to form the core body directly as a permanent magnetic ring magnet, to which the latching devices can be latched directly, without forming specially contoured latching connection sections on the ring magnet.

By the latching means forming the peripheral outer wall of the piston, they are also located with the greatest possible radial distance to the center of the piston, where they can fulfill their holding function as best as possible. In addition, the outer surfaces of the Verrastungseinrichtungen can be used as needed immediately as a guide surface for guiding the piston during its intended use, so that the same components of the piston can be used for different purposes.

The piston according to the invention also has the advantage that, after latching, it constitutes an assembly that holds itself out of itself. As a connecting member for the two at least partially made of plastic material piston elements is placed between the piston elements and preferably one-piece core body to which the two piston elements are fixed independently by locking, so that no additional clamping elements are required to hold the various piston components axially together. When assembling a piston, it is possible first to lock the core body with one of the piston elements, so that it is held captive on this piston element. Then, the second piston element can also be latched with the core body, wherein the core body is flanked by the Verrastung radially outwardly of the Verrastungseinrichtungen, which simultaneously form the piston radially outwardly bounding peripheral outer wall of the piston. Depending on the configuration of the latching devices, this peripheral outer wall may be continuous at least substantially or may also have, for example, one or more recesses which are suitable, for example, for use as a depot for a lubricant.

As with the one in the EP 1 899 611 B1 also described in the present invention on the basis of the piston assembly according to the invention, a modular system for producing different pistons can be realized, wherein one provides different piston elements, which are combined selectively from case to case by mediation of the core body to the desired piston. The piston elements may differ, for example, in their material or in the design of the piston seal. By the way, a piston seal can definitely be attached to any piston element be present, for example, where it is possible to equip only a piston member with a piston seal when the piston is intended for a single-acting cylinder, or to provide each piston member with a piston seal when the piston is intended for use with a double-acting cylinder.

Advantageous developments of the invention will become apparent from the dependent claims.

Expediently, each piston element has a disc-shaped base body made of plastic material, on which the associated latching device is formed in one piece. Such a basic body can be produced, in particular by injection molding, including the latching device. If the piston element also has a piston seal, the same is expediently formed by injection molding on the base body. Body and piston seal are preferably realized as two-component injection molded parts, which allows an extremely efficient production.

Overall, each piston element expediently contains a core portion flanking the core body axially and axially projecting in the region of the outer edge of this disc portion with respect to the disc portion coaxial arrangement collar portion, wherein the collar portion forms the Verrastungseinrichtung the relevant piston element.

The latching devices can be designed such that they overlap the core body axially over only part of its length. However, this regularly requires the formation of a locking groove on the outer peripheral surface of the core body, which adversely affects its production costs. It is therefore considered to be considerably more advantageous if the latching devices are designed such that they overlap the core body radially on the outside over its entire axial length. Here then a special design of the outer peripheral surface of the core body is unnecessary, so that it can be designed with a very simple geometry and in particular with a cylindrical outer peripheral surface. This proves to be particularly advantageous if a component used for position detection and made of a permanent magnetic material is used as the core body.

A particularly advantageous embodiment of the Verrastungseinrichtungen provides that selbige each have a plurality of distributed around the center of the associated piston element around arranged latching hooks which each protrude axially in the direction of the other piston element and thereby engage over the core body at its radially oriented outer periphery. The catch hooks are preferably designed to perform a snap function so that they automatically snap on the core body when a piston member and the core body are axially compressed. In the latched state, the piston element is expediently supported on the one hand on an axial end face of the core body, while the latching hooks engage around the core body and engage behind it on the oppositely oriented axial end face.

The two latching devices are expediently designed so that they overlap in the axial direction of the piston. Inter alia, in this context, it is advantageous if the latching hooks of each piston element are arranged in the circumferential direction of the piston element at a distance from each other, so that there is a hook ring in which in the circumferential direction of the piston element latching hook and alternate between hook-free gaps. If both piston elements are locked to the core body, the latching devices of the two piston elements can engage each other axially in such a way that in each case at least one latching hook of the respective latching device dips into a gap of the respective other latching device. In this case, it is particularly advantageous if exactly one latching hook of the respective other latching device engages in each gap of the one latching device.

Conveniently, the latching hooks of the two latching devices together form the peripheral outer wall of the piston radially outwardly delimiting the piston.

When the piston member is designed to have a disc portion and an associated collar portion as described above, the collar portion is suitably formed by a hook ring consisting of a plurality of successive in the circumferential direction of the piston member and each separated by a gap Latching hook composed.

It is considered to be particularly advantageous if the latching hooks and the gaps of the latching devices are designed to be coordinated with one another in such a way that an at least substantially closed peripheral outer wall of the piston results if the latching devices mesh with one another. In particular, it is possible to make the latching devices such that their outer contours are at least substantially complementary, so that they rest against one another in the state locked to the core body or at most are spaced apart from each other only with a small gap. This results in a optimum shielding of the core body towards the surroundings of the piston.

However, the aforementioned complementary design of the outer contour is also of particular advantage when the peripheral outer wall of the piston formed by the Verrastungseinrichtungen is to be used directly as a guide surface, which cooperates in the proper use with the piston running surface of the housing of a fluid-operated working cylinder slidably. In such a case can be dispensed with in an advantageous manner on an additionally applied to the piston guide band.

But even if the defined by the locking hook peripheral outer wall of the piston is patchy, because, for example, the latching hooks of the two latching devices or only partially abut each other, the outer surfaces of the latching hooks can be readily used as a guide surface of the type just described.

The functioning as a connecting member between the two piston elements core body is advantageously formed in one piece. It may be, for example, a ring body or a disk body, the latter, to allow easy fixation of the piston to a piston rod, can also be centrally perforated.

Preferably, the core body has permanent magnetic properties. This is the case when it is to be used in the operation of the associated working cylinder for detecting the piston position.

The core body used for latching connection with the two piston elements is expediently one of several components a arranged between the two piston elements multi-part core structure. This core structure is expediently enclosed at least for the most part by the two piston elements. The core structure can be used advantageously for stiffening the piston whose piston elements are made of plastic material.

A multi-part core structure expediently comprises an annular core body and a disk body concentrically enclosed by this annular core body and designated as a core disk. In such a multi-part design, the materials of the core body and the core disk can be selected independently of each other depending on the function. For example, an annular core body used as a ring magnet for position detection may be made of a permanent magnetic material, while a core disk used at least mainly for stiffening may be made of a less expensive metal, particularly an aluminum material or another, preferably non-ferromagnetic metal.

If no position detection is to be made with the piston, instead of a ring magnet, an annular core body consisting of another material can also be used. In any case, the division of the core structure has the advantage that the core disk can be combined as required with an either permanent magnetic or non-permanent magnetic annular core body.

In principle, the core structure may be executed in one piece, deviating from the above explanations. In this case, the core structure is formed directly from the preferably one-piece core body.

The core disk is preferably perforated centrally, so that the piston can be easily combined with a piston rod. Such a piston rod can be inserted with a fastening portion through the centrally perforated piston.

Figur 1

eine bevorzugte Bauform des erfindungsgemäßen Kolbens in einem Längsschnitt gemäß Schnittlinie I-I aus Figur 3 im auf einer Kolbenstange montierten Zustand, wobei ein Bereich der Rastverbindung der Kolbenbestandteile separat nochmals vergrößert abgebildet ist und wobei strichpunktiert weitere Komponenten eines Arbeitszylinders angedeutet sind, der mit dem erfindungsgemäßen Kolben ausgestattet ist,

Figur 2

eine perspektivische Einzeldarstellung des an der Kolbenstange gemäß Figur 1 befestigten Kolbens,

Figur 3

die Einzelteile des Kolbens vor dem Zusammenbau in einer perspektivischen Explosionsdarstellung,

Figur 4

die in Figur 3 gezeigten Komponenten in einem Längsschnitt gemäß Schnittlinie IV-IV und

Figur 5

eine perspektivische Einzeldarstellung des in Figur 3 rechts abgebildeten Kolbenelementes mit Blick auf die die Verrastungseinrichtung aufweisende Stirnseite.

The invention will be explained in more detail with reference to the accompanying drawings. In this show:

FIG. 1

a preferred design of the piston according to the invention in a longitudinal section along section line II FIG. 3 in the mounted on a piston rod state, wherein a portion of the latching connection of the piston components is shown separately enlarged again and wherein dash-dotted lines further components of a working cylinder are provided, which is equipped with the piston according to the invention,

FIG. 2

an individual perspective view of the piston rod according to FIG. 1 attached piston,

FIG. 3

the individual parts of the piston before assembly in a perspective exploded view,

FIG. 4

in the FIG. 3 shown components in a longitudinal section along section line IV-IV and

FIG. 5

a perspective individual representation of in FIG. 3 Right piston member shown with a view of the latching device having end face.

The FIG. 1 shows, in partly schematic representation, a fluid-operated generally designated by reference numeral 1 Working cylinder. It is particularly suitable for operation with compressed air, but can also be driven with another gaseous medium or with a hydraulic medium.

The working cylinder 1 has a housing 3 with a cylinder tube 4, the front side of two housing covers 5, 6 is completed. One of these housing cover 5 is penetrated by a central passage opening 7, are arranged in the guide and sealing means, not shown, which cooperate with a through opening 7 in a linearly displaceable manner passing through the piston rod 8 leading and sealing.

The housing 3 defines a cylinder chamber 12, in which on the inner end portion of the piston rod 8 of the piston 13 according to the invention is attached. The piston 13 divides the cylinder chamber 12 into two axially successive working chambers 14a, 14b, into each of which a separate housing 3 passes through the fluid channel 15a, 15b opens.

The fluid channels 15a, 15b are used for controlled fluid admission of the working chambers 14a, 14b to drive the piston 13 to a rectified with its longitudinal axis 16 linear motion and to position as needed. The movement and position of the piston 13 can be tapped outside the working cylinder 1 on the piston rod 8.

The working cylinder 1 can advantageously be equipped with dot-dashed position detection means 17, which enable the detection of at least one relative to the housing 3 occupied position of the piston 13. The position detection means 17 are, for example, a displacement measuring system or one or more Sensors such as Hall sensors or reed switches. The position detecting means 17 are fixed outside the cylinder chamber 12 fixed to the housing or fixable. The position detection means 17 are activated by an actuating element 18 embodied as part of the piston 13, which preferably consists of a permanent-magnetic material.

The piston 13 is a composite of several components assembly and can also be handled in the non-mounted on a piston rod 8 state as a single component. The assembly of the piston 13 on a piston rod 8 thus takes place as a functional whole and not in the form of individual parts.

As in particular from FIGS. 1 . 3 and 4 it can be seen, the piston 13 includes a core structure 20 and two to the core structure 20 and also coaxial, first and second piston elements 23a, 23b. The two piston elements 23a, b jointly enclose the core structure 20. They are mounted coaxially on the core structure 20 by means of a respective first or second latching device 24a, 24b provided independently of each other and axially opposite sides. In this case, both piston elements 23a, b are latched with their latching device 24a, b with one and the same component of the core structure 20 designated as the core body 25. Each piston element 23a, b is thus axially immovably connected by latching with the core body 25, regardless of the respective other of the two piston elements 23a, b.

The core body 25 thus acts as a link between the two piston elements 23a, 23b by holding them together. A direct holding connection or locking connection between the two piston elements 23a, 23b is not available.

Conveniently, the actuator 18 is formed directly from the core body 25. Accordingly, both piston elements 23a, b are latched independently of one another with the actuating element 18. By way of example, the core body 25 consists of a material with permanent magnetic properties.

It is advantageous if the core body 25 is a one-piece component.

Preferably, the core body 25 is annular and arranged concentrically to the longitudinal axis 16.

The core structure 20 is expediently designed in several parts. By way of example, it consists of the already mentioned, expediently ring-shaped core body 25 and a disc-shaped element designated as core disk 26, which is concentrically enclosed by the annular core body 25.

The core body 25 expediently has a circular inner contour, while the core disk 26 has a circular outer contour. Both contours are suitably designed circular cylindrical. In addition, they are expediently coordinated so that the annular core body 25 sits directly on the radially oriented outer periphery 27 of the core disk 26.

The core plate 26 functions expediently as a supporting element of the piston 13. It is preferably made of stainless steel or aluminum. Such material is not magnetizable and thus can not affect the functionality of the preferably permanent magnetic core body 25 or actuator 18.

The core disk 26 is centrally perforated and has a centrally disposed, axial through hole 28. During assembly, the piston 13 is fitted with this through hole 28 on a cylindrical mounting portion 32 of the piston rod 8.

In one embodiment, not shown, the core structure 20 is integrally formed and formed directly from the core body 25. In this case, the core body 25 has the shape of a perforated annular disc and is provided with the through hole 28. It can then be designed depending on the purpose permanent magnetic or non-permanent magnetic, in any case it preferably consists of metal.

Incidentally, it is also possible to resort to a multi-part core structure of the type described even if the core body 25 is not used as an actuating element 18. The core body 25 can then consist of a low-cost, non-permanent magnetic material, for example of plastic material or of aluminum. It is clear that in this way a modular concept can be pursued in which a piston 13 according to its purpose according to standard with the same core plate 26, but alternatively can equip with different core bodies 25.

The stiffening functionality of the core structure 20 is above all also advantageous because the two piston elements 23a, 23b each consist at least partially and preferably in their entirety of a plastic material.

Even if the core structure 20 is designed in several parts, preferably only the radially outer core body 25 is involved in the latching connection with the two piston elements 23a, b. The optional core disk 26 is inserted between the two piston elements 23a, 23b without axially acting positive connection, which is in particular a loose interposed insert. However, it is expediently an axially backlash-free connection in that the two piston elements 23a, b rest on the axially oriented end faces of the core disk 26 due to their latching fixation with axial prestressing. The same is therefore expediently clamped axially immovably between the two piston elements 23a, b.

The core structure 20 has at its the through hole 28 defining component - exemplified at the core disk 26 - two formed on opposite end faces, axially projecting and concentric with the longitudinal axis 16 annular axial projections 29. They serve for a purpose of clamping the piston 13 on a piston rod eighth and on the other hand for centering the two piston elements 23a, b. The latter each have a central axial opening 33 into which an annular axial projection 29 is inserted in a centering manner during the axial assembly of the piston components. As a result, the piston elements 23a, b and the core structure 20 are mutually centered and fixed immovably relative to each other in the radial direction.

As in particular the Figures 3 and 5 can be easily seen, the two piston elements 23a, 23b may be designed substantially cup-shaped or plate-shaped. They each have a core portion 20 and thus also the core body 25 axially flanking disc portion 34a, 34b and in the region of the outer edge of the disc portion 34a, b of this disc portion 34a, b in this coaxial arrangement axially projecting collar portion 35a, 35b.

The collar sections 35a, b each form one of the two latching devices 24a, 24b.

Incidentally, by way of example, each piston element 23a, 23b is provided in the region of its radially outer region with a circumferential piston seal 36a, 36b, which is concentric with the longitudinal axis 16. These piston seals 36a, 36b are in the assembled cylinder 1, preferably with a sealing lip, at the defined by the inner peripheral surface of the cylinder tube 4 cylindrical piston tread 37 dynamic sealing and prevent fluid transfer between the two working chambers 14a, 14b. The associated piston seal 36a or 36b can be dispensed with on one of the piston elements 23a or 23b if the working cylinder 1 is a so-called single-acting working cylinder in which only one of the working chambers 14a or 14b is subjected to pressure medium during operation.

The latching devices 24a, 24b are designed such that, when the piston 13 is assembled, they engage over the core body 25 in the axial direction at its radially outwardly pointing outer circumference 38, which is preferably circular-cylindrical. It is advantageous if the core body 25 is overlapped by each latching device 24a, 24b over its entire axial length. This is the case in the embodiment.

Especially from FIGS. 1 and 2 It can be seen very clearly that the two latching devices 24a, 24b in the assembled state of the piston 13 together form a peripheral outer wall 42 of the piston 13 extending around the core body 25. This peripheral outer wall 42 defines radially outward one of the two piston elements 23a, 23b together enclosed receiving chamber 43, in which the core structure 20 is received.

The receiving chamber 43 is expediently undivided in respect of the longitudinal axis 16 radial direction and has no intermediate walls.

Said peripheral outer wall 42 is not covered by any further components of the piston 13 on its radially outwardly oriented outer surface 44 which extends around the piston 13 in the circumferential direction of the longitudinal axis 16 and which is preferably at least substantially cylindrical. It can therefore be used in an advantageous manner as a guide surface 45 which slidably rests in the assembled state of the working cylinder 1 on the piston tread 37 and by dynamic interaction with this piston tread 37 causes a linear guide of the piston 13 in its linear movement. It is therefore unnecessary to coaxially set up on the piston 13 an additional, defining a guide surface guide band.

By the latching means 24a, 24b engage radially around the core structure 20 around, they can be optimally designed and have a relatively large radial distance to the longitudinal axis 16, which promises good holding forces. In addition, an advantageous multiple function can be realized by the latching means 24a, 24b not only serve for locking, but at the same time also form the piston 13 peripherally terminating outer wall 42.

Conveniently, the disc portion 34a, 34b of each piston member 23a, 23b includes a disk made of a stable plastic material, to form the associated axially perforated disk-shaped base body 46. The mutually facing axial inner surfaces of these disc-shaped base body 46 form the two mutually facing axial boundary surfaces 43a, 43b of the receiving chamber 43 and are graduated in the embodiment in the radial direction multiple ring. The boundary surfaces 43a, b are in particular designed so that the axial width of the receiving chamber 43 is reduced from radially inward to radially outward with each annular graduation by a certain amount.

In particular, by molding by means of a two-component injection molding process, the piston seals 36a, 36b are integrally formed on the respective associated base body 46. In this way, a cohesive, intimate connection between the rubber-elastic material of each piston seal 36a, 36b and the relatively hard plastic material of the associated base body 46 results.

Preferably, the piston seals 36a, 36b are each an integral part of an elastomer body 47, which is formed on the axial boundary surface 43a, 43b of the associated body 46 axially opposite end face outer surface 48 of a respective body 46. Each of these elastomeric bodies 47 can form one or more axially projecting from the piston 13 buffer projections 52 which mitigate the impact on the housing covers 5, 6 in the Hubendlagen the piston 13.

Preferably, at least the core body 25 of the core structure 20 is resiliently clamped between the two piston elements 23a, 23b. This prevents the core body 25 due to vibration during operation is damaged. At the same time it is securely fixed axially.

The elastically yielding clamping is preferably realized in that axially opposite the core body 25 on one or both boundary surfaces 43a, 43b, a rubber-elastic support structure 53 is present, which protrudes slightly into the receiving chamber 43 via the associated axial boundary surface 43a, 43b. By way of example, the support structure 53 consists of a plurality of rubber-elastic support elements 53a distributed around the same in a concentric arrangement with respect to the longitudinal axis 16, which are expediently an integral part of the elastomer body 47 arranged on the associated main body 46. By way of example, each disk-shaped main body 46 has at least one region axially opposite the core body 25 via a plurality of apertures 54 through which the elastomeric material of the elastomeric body 47 engages from the outside in order to form support elements 53a of the supporting structure 53 protruding locally over the boundary surface 43a, 43b. of which the core body 25 is acted upon axially.

The above-mentioned latching devices 24a, 24b are preferably integrally formed on the base body 46 of the relevant piston element 23a, 23b. They are located on the inner side of the respective base body 46, axially facing the respective other piston element 23a, 23b, at its radially outer outer edge region 55. In this way, each latching device 24a, 24b forms the collar section 35a, 35b of the relevant piston element 23a. 23b.

The first latching device 24a belonging to the first piston element 23a consists of a plurality of parts distributed around the center of the piston element 23a first latching hook 56a. In a corresponding manner, the second latching device 24b belonging to the second piston element 23b comprises a plurality of second latching hooks 56b, which are arranged distributed around the center or the longitudinal axis 16 of the second piston element 23b. The first latching hooks 56a of the first piston element 23a protrude in the direction of the second piston element 23b, while the second latching hooks 56b arranged on the second piston element 23b project in the direction of the first piston element 23a. In this case, the latching hooks 56a, 56b engage over the outer periphery 38 of the core body 25, respectively.

Each latching hooks 56a, 56b has a one-piece arranged integrally on the base body 46 and projecting therefrom in the direction of the other base body 46 web portion 57. In addition, each latching hook 56a, b via a locking projection 58 which protrudes at the projecting from the base body 46 free end of Web portion 57 is arranged and with respect to the longitudinal axis 16 points radially inward. The web portions 57 give a respective latching hooks 56a, 56b the necessary radial bending elasticity for the latching process.

Furthermore, the latching hooks 56a, 56b of each latching device 24a, 24b are arranged at a distance from each other in the circumferential direction, that is to say around the longitudinal axis 16, in particular lying on a circular line. As a result of the spacing, there is a gap between circumferentially immediately adjacent latching hooks 56a, 56b, which in the case of the first piston element 23a is referred to as the first gap 62a and 62b in the case of the second piston element 23b as the second gap 62b.

Each latching device 24a, 24b thus expediently presents itself as a hook ring, which in the case of the first piston element 23a is formed in the piston circumferential direction alternately successive first latching hook 56a and first gaps 62a and in the case of the second piston member 23b in the piston circumferential direction alternately successive second latching hook 56b and second gaps 62b composed.

In the assembled state of the piston 13, the piston elements 23a, 23b are arranged relative to one another in such an angular position that the first latching hooks 56a dive axially into the second gaps 62b and at the same time the second latching hooks 56b engage axially in the first gaps 62a. In this way, the first and second latching hooks 56a, 56b overlap in the axial direction of the piston 13. Preferably, in each gap 62a, 62b of the one latching device 24a, 24b, exactly one latching hook 56b, 56a of the other latching device 24b, 24a engages one. In this way, the latching hooks 56a, 56b can engage over the core body 25 on its outer circumference 38 in each case over its entire axial length.

The latched core body 25 is supported on each piston element 23a, 23b on the one hand on its axial boundary surface 43a, 43b or on the respective axial support surface 43a, 43b respectively associated support structure 53. At its axially opposite end face of the core body 25 is engaged behind by the locking projections 58, which are located at the free end of the web portions 57, of which the core body 25 is flanked radially outward.

In its circumferential direction about the longitudinal axis 16 around the core body 25 is thus alternately latched with the first and second latching hooks 56 a, 56 b.

As can be seen, in the exemplary embodiment, the peripheral outer wall 42 of the piston 13 is formed by the latching hooks 56a, 56b of the two latching devices 24a, 24b.

The preferably existing guide surface 45 is accordingly formed by the latching hooks 56a, 56b and is composed of individual, successive in the piston circumferential direction surface portions which are defined in particular by the web portions 57 of the latching hooks 56a, 56b.

It is advantageous and in particular also favors the assembly of the mutually engaging piston elements 23a, 23b, when the latching hooks 56a, 56b each have a lateral outer contour which tapers towards its free end. The lateral outer contour means the two side edges 63, 64 of a respective latching hook 56a, 56b which point in opposite circumferential directions of the piston 13. The latching hooks 56a, 56b and in particular their web sections 57 thus taper, starting from the base body 46 carrying them, in the direction of the free end, as their width measured in the circumferential direction of the piston 13, in particular gradually, becomes smaller.

As a result of this design of the latching hooks 56a, 56b, it follows that the lateral inner contours of the first and second gaps 62a, 62b expand towards the open end of the respective gap 62a, 62b. The circumferentially facing each other side edges 63, 64 of successive in the piston circumferential direction latching hooks 56a, 56b respectively define the flared lateral inner contour of a gap 62a, 62b at the same time.

It is advantageous if the latching hooks 56a, 56b are distributed uniformly in the circumferential direction of the piston 13. It Furthermore, it is advantageous if the taper angles of the latching hooks 56a, 56b of the two latching devices 24a, 24b are designed to coincide. Finally, it is advantageous if the latching hooks 56a, 56b belonging to the same latching device 24a, 24b are arranged spaced from one another in the circumferential direction of the piston 13 such that in the latched state of both piston elements 23a, 23b, the latching devices 24a, 24b dipping axially into one another at least in the Essentially closed peripheral outer wall 42 of the piston 13 form.

The latter is the case in the exemplary embodiment in which the latching hooks 56a, 56b of the respectively one latching device 24a, 24b have a lateral contour which is at least substantially complementary to the gaps 62a, 62 of the respective other latching device 24a, 24b.

In particular, it can be achieved that, in the interlocking state of the two latching devices 24a, 24b, the first latching hooks 56a abut with their side edges 63, 64 on the side edges 63, 64 of the second latching hooks 56b or are only minimally spaced therefrom.

Due to the mutually complementary design of latching hooks 56a, 56b and gaps 62a, 62b can also be achieved in an advantageous manner that the two piston elements 23a, 23b perform even during shaking during operation no relative rotational movement to each other.

The locking means 24a, 24b are expediently, as is apparent in the embodiment, formed like a tooth, in particular in the manner of Axialverzahnungen, wherein the latching hooks 56a, 56b form the "teeth" of the toothing.

In an embodiment not shown, the latching hooks 56a, 56b in the circumferential direction of the piston 13 are slightly narrower than the gaps 62a, 62b located between them, so that in the latched to the core body 25 state of the two piston elements 23a, 23b between the latching hook 56a of first latching means 24a and the latching hooks 56b of the second latching means 24b remain spaces which are usable, for example, to store a suitable lubricant to obtain a permanent lubrication.

It is striking in the latching measures of the various piston components that the latching devices 24a, 24b engage radially over the entire core structure 20 enclosed by the two piston elements 23a, 23b and do not intervene between or into the core structure 20, so that the function of a piston 13 at the same time is radial outer terminating peripheral outer wall 42 is available.

If the core structure 20 is formed in several parts with concentrically enclosing components, as is the case in the exemplary embodiment, the core disk 26 can be realized as a simply designed and easily manufactured rotary part, on which no recesses for the interaction with the locking device 24a, 24b are required. Also, the core body 25 may be a simple ring body without radial recesses, so that it can be produced inexpensively.

For attachment to a piston rod 8 can be provided that the piston 13 is fitted with its through hole 28 on the mounting portion 32 and between an annular step 65 of the piston rod 8 and one on the piston rod 8 screwed fastening nut 66 is axially immovably clamped.

The two elastomeric bodies 47 expediently protrude far enough radially inward in order to be able to come into sealing contact in the state of the piston 13 mounted on the piston rod 8 with one end face each of the annular step 65 and the fastening nut 66. In this area, the elastomeric body 47 may have a circumferential, axially slightly protruding sealing edge.

The two piston elements 23a, 23b are expediently designed as identical parts, so that only a single type of piston element has to be manufactured in order to realize a piston 13.

Notwithstanding the embodiment, it is also possible not to perform the latching hooks 56a, 56b with tapered contour, but with parallel to the longitudinal axis 16 side edges 63, 64. The tapering towards the free end shape but facilitates the axial assembly considerably.

The tapered contour of the latching hooks 56a, 56b could also be realized by curved side edges 63, 64. The latching means 24a, 24b may be contoured in particular wave-shaped, with in the circumferential direction of the piston 13 alternately successive convex portions and concave portions, wherein the convex portions of the latching hooks 56a, 56b and the concave portions of the gaps 62a, 62b are formed.

Claims (15)

Piston for a working cylinder, with two at least partially made of plastic material piston elements (23a, 23b), of which at least one radially outwardly disposed piston seal (36a, 36b) and from each other axially opposite sides by means of a locking means arranged on each ( 24a, 24b) are independently coaxially latched onto a core body (25) of the piston (13) arranged between them so that they are held together axially by the core body (25), the latching means (24a, 24b) supporting the core body (25). engage over at its radially outwardly facing outer periphery (38), characterized in that the Verrastungseinrichtungen (24a, 24b) of the two piston elements (23a, 23b) are formed and arranged so that they together one around the core body (25) extending around forming peripheral outer wall (42) of the piston (13). Piston according to Claim 1, characterized in that each piston element (23a, 23b) has a disc-shaped basic body (46) made of plastic material, on which the associated latching device (24a, 24b) is integrally formed, wherein the at least one piston seal (36a, 36b ) is expediently by injection molding to the base body (46) molded component. Piston according to claim 1 or 2, characterized in that each piston element (23a, 23b) has a core portion (25) axially flanking disc portion (34a, 34b) and in the region of the outer edge of the disc portion (34a, 34b) of the disc portion (34a , 34b) in this coaxial arrangement axially projecting collar portion (35a, 35b), wherein the collar portion (35a, 35b), the latching means (24a, 24b) of the respective piston element (23a, 23b) forms. Piston according to one of claims 1 to 3, characterized in that the latching means (24a, 24b) engage over the core body (25) in each case over its entire axial length. Piston according to one of claims 1 to 4, characterized in that the latching means (24a, 24b) of each piston element (23a, 23b) distributed over a plurality of around the center of the associated piston element (23a, 23b) arranged around and in the direction of the other piston element (23b, 23a) has protruding latching hooks (56a, 56b) which engage over the core body (25) on its outer circumference (38). Piston according to claim 5, characterized in that the latching hooks (56a, 56b) of each latching device (24a, 24b) in the circumferential direction of the piston element (23a, 23b) are arranged at a distance from each other, so that between immediately adjacent latching hooks (56a, 56b ) in each case a gap (62a, 62b) is located, wherein the latching means (24a, 24b) of the two piston elements (23a, 23b) engage axially into one another such that the latching hooks (56a, 56b) of the respective one latching device (24a, 24b) respectively submerge in a gap (62b, 62a) assigned to the respective other latching device (24b, 24a). Piston according to claim 6, characterized in that in each gap (62a, 62b) of the respective one piston element (23a, 23b) in each case exactly one latching hook (56b, 56a) of the latching device (24b, 24a) of the respective other piston element (23b, 23a ) intervenes. Piston according to claim 6 or 7, characterized in that the core body (25) enclosing peripheral outer wall (42) of the piston (13) of the latching hooks (56a, 56b) of the two Verrastungseinrichtungen (24a, 24b) is formed. Piston according to one of claims 6 to 8, characterized in that the latching hooks (56a, 56b) of the respective one latching device (24a, 24b) to the latching hooks (56b, 56a) of the other latching device (24b, 24a) at least substantially have complementary lateral outer contour, so that an at least substantially closed peripheral outer wall (42) of the piston (13) is formed by the interlocking latching means (24a, 24b). Piston according to one of claims 6 to 9, characterized in that the latching hooks (56a, 56b) each have a tapering towards its free end lateral outer contour, in particular in each case - in the radial direction of the piston (13) viewed - with respect to the axial direction of the piston (13) oblique side edges (63, 64). Piston according to one of Claims 1 to 10, characterized in that the peripheral outer wall (42) of the piston (13) formed by the latching devices (24a, 24b) with its outer surface (42) radially remote from the core body (25) is one of none forms further components of the piston (13) covered guide surface (45), which cooperate is provided with a piston running surface (37) of the piston (13) in the operating state receiving housing (3) of a fluid-operated working cylinder (1). Piston according to one of claims 1 to 11, characterized in that the core body (25) is a one-piece component. Piston according to one of claims 1 to 12, characterized in that the core body (25) has permanent magnetic properties. Piston according to one of claims 1 to 13, characterized in that the core body (25) a component of one of the two piston elements (23a, 23b) and with respect to the piston elements (23a, 23b) separate, multi-part core structure (20) of the piston ( 13). Piston according to claim 14, characterized in that the core structure (20) of the piston (13) has a core disc (26), which expediently consists of metal, wherein the core body (25) is annular and concentrically surrounds the core disc (26), wherein expediently the annular core body (25) sits directly on the outer circumference (27) of the core disc (26).

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