DE102017206298A1 - Drive unit, fluid operated cylinder equipped therewith and related manufacturing method - Google Patents

Abstract

A drive unit (11) and a fluid-actuated working cylinder (1) equipped therewith are proposed, the drive unit (11) having a drive piston (5) and a piston rod (8), the drive piston (5) having a piston rod (8). radially superior piston body (38), which is combined with the piston rod (8) to a one-piece piston-piston rod assembly (54). The piston-piston rod assembly (54) consists including its piston body (38) and its piston rod (8) made of a carbon fiber reinforced plastic embedded in a plastic matrix Kohlenstofffasern.Auf this way, there is a high weight saving with optimized sliding behavior of relatively moving components ,

Description

The invention relates to a drive unit for a fluid-actuated working cylinder, which includes a drive piston and a piston rod, wherein the drive piston has a piston rod radially projecting piston body, which is combined with the piston rod to a one-piece plastic piston-piston rod assembly.

The invention further relates to a fluid-actuated working cylinder having a cylinder housing defining a housing interior, in which a drive piston of a piston rod further comprising a drive unit is arranged linearly displaceable, wherein the drive piston has a piston rod radially projecting piston body, with the piston rod to a Plastic existing one-piece piston-piston rod assembly is summarized.

The invention further relates to a manufacturing method for such a drive unit and for such a fluid-operated working cylinder.

Such a trained working cylinder, which consists entirely of plastic apart from sealing elements, is made of the US 3,703,125 known. It has a two-part cylinder housing having a first housing part, which includes a cylinder tube and an end wall, and a second housing part, which is formed by a bolted to the cylinder tube end cover, through which extends a piston connected to a drive piston rod, a through Fluid supply to form a displaceable drive unit of the working cylinder. The piston rod is combined in one piece with a piston body carrying a piston seal to form a piston body-piston rod assembly. For the realization of the various cylinder components, numerous plastic materials are mentioned, including, for example, nylon, polyvinyl chloride and glass fiber reinforced polycarbonate. The use of plastic as a material allows cost-effective production. In addition, plastic, as far as it is not interspersed with glass fibers, good sliding properties, which is advantageous in order to realize the required between piston, piston rod and cylinder housing sliding surfaces. Unreinforced plastic material, however, is subject to restrictions in strength and stability, so that the practical applications are limited and especially large-sized and / or high operating pressures exposed components of working cylinders for a realization of unreinforced plastic are less suitable. In glass fiber reinforced plastic, these shortcomings do not exist, but here the inorganic glass fibers can affect the sliding surfaces in contact with each other and have a high and rapid wear.

From the DE 101 41 560 C2 a fluid-actuated working cylinder is known, which has an existing from a front housing part and a fixed end cover thereon cylinder housing. The housing front part can be made in one piece as an injection molded part made of plastic material. Even with the end cover can be a plastic part. In the interior of the cylinder housing is a drive piston, which is summarized for example by a welded joint with a piston rod to form a structural unit. As material for the piston rod and a piston body of the drive piston in particular aluminum material is provided.

From the AT 298923 A a working cylinder is known, which has a cylinder housing, which is composed of a first housing part produced by deep drawing and a cover attached to the housing part. In the housing part produced by deep drawing, an end wall and a cylinder tube are integrally combined.

The DE 10 2010 008 349 A1 describes a process for producing pellets of fiber composites, the pellets containing carbon fibers and a thermoplastic matrix material. These pellets are suitable for further processing in a plastics manufacturing process. Carbon fibers can generally be used as fiber reinforcement of thermoplastic or thermoset bonded fiber composites.

The invention has for its object to make measures that favor a cost-effective production of a stable and low-wear fluid-actuated working cylinder and a drive unit of such a working cylinder.

To achieve this object, it is provided both in a drive unit of the type mentioned above and in a fluid-operated cylinder of the type mentioned that the piston body-piston rod assembly including the piston body and the piston rod consists of a carbon fiber reinforced plastic embedded in a plastic matrix carbon fibers

The object is further achieved by a production method in which at least the piston body-piston rod assembly consisting of a carbon fiber-reinforced plastic with carbon fibers embedded in a plastic matrix is produced by injection molding

Both the piston body and the piston rod integrally formed therewith are made of carbon fiber reinforced plastic with carbon fibers embedded in a plastic matrix and are integral parts of a one-piece piston-body piston rod assembly made entirely of carbon fiber reinforced plastic with carbon fibers embedded in a plastic matrix. Such a design of the piston-piston rod assembly allows a cost-effective and efficient production of a low-weight fluid-operated working cylinder. A low weight is for example advantageous if the working cylinder is moved in its total use, for example, due to its integration into a handling unit or a robot. A low weight of the piston-piston rod assembly also allows high accelerations of the drive unit with a relatively low energy consumption. In addition, the piston-piston rod assembly can be prepared by well manageable plastic processing method, in particular by injection molding or extrusion, if the plastic matrix consists of a thermoplastic material. In a preferred Spritzgießherstellung the piston-piston rod assembly made of carbon fiber reinforced plastic, a predominant parallel orientation of the carbon fibers is observed, which obviously has a favorable effect on the structural properties and wear behavior. In the area of surfaces sliding off one another, there is a sliding support effect of the mechanically very stable carbon fibers. In this case, a nonabrasive effect of the fiber ends of the carbon fibers is observed in comparison to glass fibers. The fiber reinforcement by means of carbon fibers leads to a very high strength, rigidity and stability. It is also advantageous that in the production of the piston-piston rod assembly without special alignment measures an exact coaxiality between the piston body and the piston rod can be achieved. As has also been shown, resulting in carbon fibers compared to glass fibers no abrasive properties, so that the carbon fiber reinforced plastic when used in conjunction with a fluid-operated cylinder with very good tribological properties. A equipped with the existing carbon fiber reinforced plastic piston body piston rod assembly working cylinder thus has a long service life with low maintenance.

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

Due to the already mentioned good sliding properties of the carbon fiber reinforced plastic, it is advantageous if the radially outwardly facing outer peripheral surface of the piston body is formed as a in the use of the drive unit directly on the inner peripheral surface of a cylinder tube of a fluid-actuated working cylinder slidably radially supporting piston guide surface. Especially in combination with a likewise made of a carbon fiber reinforced plastic cylinder tube results in a particularly smooth running behavior of the drive piston with respect to the cylinder tube.

If a particularly low-friction working cylinder is to be realized, can be dispensed with a slidable on the inner peripheral surface of the cylinder tube elastomeric piston seal on the part of the drive piston. The drive piston is then formed without piston seal. Here, even the piston body alone form the drive piston.

In principle, it is also possible to equip the piston body at its outer periphery with an additional guide ring, which establishes the contact between the drive piston and the cylinder tube. Such a guide ring is used for example in a radially outwardly open annular groove of the drive piston.

Preferably, the piston body made of carbon fiber reinforced plastic is provided with an annular groove open towards its radially outwardly facing outer peripheral surface. This annular groove may be empty, resulting in a weight saving results. However, the annular groove can also be used as a receiving groove for a usable for detecting the position of the drive piston activation element, in particular for receiving an annular activation element. Such an activation element can interact, for example, with a position detection device, which consists for example of one or more position sensors or of a displacement measuring system. Depending on the configuration of the position detection device, the activation element may have, for example, permanent magnetic or ferromagnetic properties.

In order for the drive piston, in the intended use of the drive unit in a housing interior of the cylinder housing of a working cylinder, to seal at least one working chamber which is acted upon by a fluidic pressure medium for actuation of the working cylinder, it is preferably provided with an elastomeric structure which forms a piston seal which is provided so as to be sealing and slidably abutting the inner peripheral surface of a cylinder tube of the cylinder housing. This elastomeric structure is attached, for example, by injection molding to the piston body and is preferably made of a thermoplastic elastomer. Alternatively, rubber, fluororubber (FKM) or other elastomers could be used.

In a preferred embodiment, the elastomer structure also additionally forms at least one impact damper having rubber-elastic properties, which is suitable for minimizing the intensity of the impact on an end wall of a cylinder housing in a stroke end position of the drive piston. Preferably, the at least one crash cushion and the piston seal are integrally formed with each other.

In order to enable a fluidic end position damping of the drive unit during operation of a working cylinder equipped with the drive unit, it is advantageous if at least one axially extending buffering extension is integrated into the piston rod in one piece. If an end cushioning is desired in both stroke directions of the drive unit, the piston rod has buffering extensions projecting from the drive piston on two opposite sides. The Pufferungsfortsatz has a larger diameter than an adjoining length of the piston rod and is intended to dive to limit a flow medium available to the outflowing pressure medium flow in a cover of a cylinder housing of the associated working cylinder when the drive unit moves to a stroke end.

In the case of the presence of two Pufferungsfortsätzen these two Pufferungsfortsätze are suitably formed of integrally interconnected lengths of a desired outer diameter piston rod longitudinal portion.

Preferably, the drive unit is partially hollow, which leads to a saving of material and consequently a cost saving and what moreover reduces the moving mass, which benefits the agility of the lifting movement.

Preferably, the drive unit has a cavity, which is divided into two axially adjoining cavity sections. Expediently, the two cavity sections each extend coaxially into the piston rod, starting from one of the two end faces of the drive unit, and are separated in a fluid-tight manner from one another by a partition wall integral with the piston rod, so that fluid passage is prevented.

Is also the cylinder tube made of a carbon fiber reinforced plastic, there is a further reduction in weight of the thus equipped working cylinder. In addition, due to the material strength even cylinder tubes with large diameter and long length can be easily realized in conjunction with low wall thicknesses. An equipped with the carbon fiber reinforced plastic existing cylinder tube working cylinder has a long service life with low maintenance.

At least on one end face of the cylinder tube, the housing interior having the drive piston is expediently delimited by an end wall of the cylinder housing. If the working cylinder is designed as a so-called plunger cylinder, in which the drive piston protrudes from the cylinder tube on one end face with a longitudinal section acting as a piston rod, the cylinder housing can be equipped with only one end wall.

Preferably, the cylinder housing is equipped on both end sides of the cylinder tube, each with a housing interior axially delimiting end wall. In this way, for example, a single-acting or a double-acting fluid-operated cylinder can be realized.

Preferably, at least one and suitably each end wall, such as the cylinder tube, is made of a carbon fiber reinforced plastic having carbon fibers embedded in a plastic matrix.

For the realization of the cylinder tube and the at least one, also made of carbon fiber reinforced plastic end wall expediently the same carbon fiber reinforced plastic is used. From the same carbon fiber reinforced plastic expediently also the piston body-piston rod assembly.

At least one end wall of the cylinder housing is slidably passed through by the piston rod of the drive unit, wherein at a located outside of the cylinder housing end portion of the piston rod, a force tap is possible to drive, for example, a machine component.

The end wall slidably slid by the piston rod expediently contains a guide bore, through which the piston rod extends axially therethrough and whose inner circumference forms a piston rod guide surface radially supporting the piston rod. The end wall equipped with the guide bore preferably consists of the carbon-fiber-reinforced plastic already mentioned, wherein the guide bore is made directly in this carbon fiber-reinforced plastic of the end wall, so that the piston rod guide surface is an integral part of the respective end wall and consists of the carbon fiber reinforced plastic of the end wall. In this way, one uses the above-mentioned tribologically favorable effect in addition to the sliding bearing of the piston rod in the penetrated by her end wall. You can save yourself in this way an additional separate guide bushing, which provides another contribution to minimizing costs.

Basically, regardless of the material of the end wall, it would be possible to insert a guide bush defining the guide bore into the end wall, in particular by means of a press-in process.

Production and assembly of the working cylinder can be further optimized by at least one end wall of the cylinder housing is formed integrally with the cylinder tube. There is then a one-piece cylinder tube end wall assembly which can be equipped with a separate end cover on the end wall of the cylinder housing opposite the integral end wall in order to define a housing interior that is closed axially on both sides.

The end wall slidably displaced by the piston rod is preferably an end wall formed integrally with the cylinder tube and thus a component of the already mentioned cylinder tube end wall assembly. However, the respective end wall can also be designed as a separate component with respect to the cylinder tube.

At least one end wall of the cylinder housing is expediently designed as with respect to the cylinder tube separate end cap. When the end cap is removed, the drive piston can then be inserted into the housing interior through the then open cylinder tube during assembly of the working cylinder. The separate end cap is secured by suitable fasteners on the cylinder housing, wherein it is the fasteners, for example, screw connection means or adhesive bonding agent for the realization of an adhesive bond. It is considered particularly advantageous if the fastening means are designed as a welded joint, which is particularly advantageous if the cylinder tube and the separate end cover made of one and the same carbon fiber reinforced plastic. The welding takes place in particular by ultrasonic welding or by friction welding.

At least one end cover, which is separate with respect to the cylinder tube, may be made of a material which deviates from the material of the cylinder tube. For example, at least one separate end cap may be made of metal. Preferably, however, each separate end cap, like the cylinder tube, is made of a carbon fiber reinforced plastic having carbon fibers embedded in a plastic matrix.

In at least one and preferably each end wall of the cylinder housing a fluid channel is expediently integrated, which opens into the housing chamber and through which a used for actuation of the working cylinder pressure fluid can be fed and / or discharged.

The fluid-operated working cylinder is preferably a pneumatic working cylinder which can be operated with compressed air. However, the working cylinder can also be designed for actuation with other fluidic pressure media, for example for actuation with a pressure fluid.

The fiber length of the embedded in the plastic matrix carbon fibers is in principle arbitrary. In particular, however, when the components made of the carbon fiber reinforced plastic are produced by injection molding or extrusion, it is advantageous if the carbon fibers are so-called short fibers. The fiber length of these short fibers is preferably in the range between 0.05 mm and 1 mm, wherein a fiber length in the range between 0.1 mm and 0.4 mm is considered optimal.

It is particularly advantageous if the proportion of carbon fibers in the carbon fiber reinforced plastic is between 5 and 60 percent by weight, preferably in the range of 40 percent by weight.

The plastic matrix, which in principle could also consist of a thermosetting plastic material, is preferably formed by a thermoplastic plastic material. Preferably, a polyamide-based plastic material is used, for example polyamide 6 or polyamide 6.6. Also advantageous is a formation of partially aromatic or fully aromatic polyamide is considered.

In a preferred manufacturing process, all components of the working cylinder made of a carbon fiber reinforced plastic with carbon fibers embedded in a plastic matrix are injection molded.

• 1 eine bevorzugte Ausführungsform des erfindungsgemäßen fluidbetätigten Arbeitszylinders in einer isometrischen Darstellung,
• 2 in einer isometrischen Darstellung einen Längsschnitt des Arbeitszylinders gemäß Schnittlinie II-II aus 1, wobei auch eine bevorzugte Ausführungsform einer einen Antriebskolben und eine Kolbenstange umfassenden Antriebseinheit ersichtlich ist,
• 3 in einer nicht isometrischen ebenen Schnittdarstellung einen der 2 entsprechenden Längsschnitt des Arbeitszylinders aus 1, wobei zu einigen strichpunktiert umrahmten Bestandteilen in separaten Ausschnittdarstellungen IIIa, IIIb und IIIc alternative Realisierungsmöglichkeiten abgebildet sind,
• 4 eine bevorzugte alternative Ausführungsform einer Antriebseinheit mit in die Kolbenstange integrierten Pufferungsfortsätzen, und
• 5 einen Längsschnitt der Antriebseinheit aus 4 gemäß der dortigen Schnittlinie V-V.

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

• 1 a preferred embodiment of the fluid-operated working cylinder according to the invention in an isometric view,
• 2 in an isometric view of a longitudinal section of the working cylinder according to section line II-II 1 in which a preferred embodiment of a drive piston and a piston rod comprehensive drive unit is visible,
• 3 in a non-isometric planar sectional view one of 2 corresponding longitudinal section of the working cylinder 1 , wherein to some dash-dotted framed components in separate detail views IIIa, IIIb and IIIc alternative implementation possibilities are shown,
• 4 a preferred alternative embodiment of a drive unit with integrated into the piston rod Pufferungsfortsätzen, and
• 5 a longitudinal section of the drive unit 4 according to the local section line VV.

In the drawing is a total reference number 1 designated fluid actuated working cylinder, which is actuated by means of a fluidic pressure medium, which is in particular compressed air. The fluid actuated working cylinder 1 So is preferred a pneumatic cylinder. Basically, the working cylinder is suitable 1 but also for actuation by means of other gaseous pressure media or by means of liquid pressure media, such as hydraulic oil.

The working cylinder 1 has a cylinder housing 2 with a longitudinal axis 3 , The cylinder housing 2 encloses a housing interior 4 in which a drive piston 5 in the axial direction of the longitudinal axis 3 is arranged linearly displaceable.

Outside the cylinder housing 2 is located with the drive piston 5 motion coupled tapping section 6 , which is the linear movement of the drive piston 5 participates. The tapping section 6 is expediently from a front side of the cylinder housing 2 outstanding outer end section 7 a piston rod 8th formed with the drive piston 5 is firmly connected. The drive piston 5 and the piston rod 8th together form a drive unit 11 that are uniform only in the axial direction of the longitudinal axis 3 relative to the cylinder housing 2 is displaceable, with the resulting movement as a drive movement 12 is designated, which is illustrated by a double arrow.

To the cylinder housing 2 belongs with respect to the longitudinal axis 3 in particular coaxially arranged cylinder tube 13 , The cylinder tube 13 limits the housing interior 4 radially outside and has a housing interior 4 facing inner peripheral surface 14 ,

The inner peripheral surface 14 is cylindrical and preferably contoured circular cylindrical. From the circular shape deviating cross-sectional shapes of the housing interior 4 but are also possible.

The cylinder tube 13 also has one with respect to the longitudinal axis 3 radially outwardly oriented outer peripheral surface 15 , The outer peripheral surface 15 is preferably cylindrical and designed in particular circular cylindrical. Preferably, the outer peripheral surface 15 apart from the greater distance to the longitudinal axis 3 the same cross-sectional contour as the inner peripheral surface 14 , Especially with regard to an easily manageable production, it is advantageous if according to the embodiment, the wall thickness of the cylinder tube 13 is consistently constant. Thus, the cylinder tube can be inexpensively designed as a simple round tube.

The cylinder tube can be formed with a constant or varying wall thickness as any profiled tube.

Axial is the housing interior 4 on both sides by one each to the cylinder housing 2 belonging end wall 16 . 17 limited. To better distinguish the two end walls 16 . 17 in the following also as first end wall 16 and as a second end wall 17 designated. The drive piston 5 is located between the two end walls 16 . 17 whose clear distance is sufficiently large to the drive piston 5 the drive movement 12 to enable.

The piston rod 8th has a smaller diameter than the drive piston 5 and it extends axially to the tapping portion 6 , being the first end wall 16 slidably interspersed. The first end wall 16 has an axially continuous guide bore 18 on, through which the piston rod 8th extends linearly through and the inner circumference of a piston rod 8th radially supporting piston rod guide surface 22 forms. The piston rod 8th lies with its outer peripheral surface 23 Slidable on the piston rod guide surface 22 and thereby is in each with respect to the cylinder housing 2 assumed axial relative position with respect to the cylinder housing 2 radially supported.

In an embodiment not illustrated, the drive piston is 5 designed as a plunger, in the function of the piston rod 8th is integrated and at one end of the cylinder tube 13 stands out, so that there is no need for an end wall.

The drive piston 5 divided the housing interior axially into two subspaces, which in the following for better distinction as the first and second working chamber 24 . 25 are designated, wherein the first working chamber 24 between the drive piston 5 and the first end wall 16 and the second working chamber 25 between the drive piston 5 and the second end wall 17 extends.

In the illustrated embodiment, the power cylinder is 1 designed as a double-acting cylinder, in which the possibility exists, both working chambers 24 . 25 for actuating the drive unit 11 controlled to apply pressure medium. The required supply and removal of the driving pressure medium can be carried out through two fluid channels 26, 27, of which a first fluid channel 26 in the first working chamber 24 and a second fluid channel 27 in the second working chamber 25 opens. Each of these two fluid channels 26 . 27 passes through the cylinder housing 2 and opens with a connection opening 26a . 27a to the outer surface of the cylinder housing 2 out. These connection openings 26a . 27a are expediently connection means 28 associated, which allow the fluid-tight connection of a fluid line, in particular a fluid tube, which is connected to a not further illustrated control valve device, through which the supply and discharge of a fluidic pressure medium is controllable. For example, the connection means 28 from one piece in the cylinder housing 2 trained internal thread formed. Alternatively, for example, separate plug connection units by pressing in the connection openings 26a . 27a be fixed.

The two fluid channels 26 . 27 preferably have the same cross-section, but in special cases can also be designed with divergent cross-sections.

Preferably, at least one and preferably each fluid channel 26 . 27 exclusively in one of the end walls 16 . 17 educated. This applies to the embodiment. Here passes through the first fluid channel 26 the first end wall 16 while the second fluid channel 27 the second end wall 17 interspersed. Accordingly, there are the connection openings 26a . 27a on the end walls 16 . 17 , The connection openings 26a . 27a opposite inner channel mouths 26b . 27b the fluid channels 26 . 27 are preferably located on the housing interior 4 facing inner axial end face 16a . 17a the relevant first or second end wall 16 . 17 ,

In an unillustrated embodiment, at least one and preferably each fluid channel passes through 26 . 27 the wall of the cylinder housing 2 at one to the assigned end wall 16 . 17 immediately adjacent place.

To the working cylinder 1 Being able to fix at the place of use is at least one and preferably every end wall 16 . 17 with at least one mechanical attachment interface 32 fitted. By way of example, there is each attachment interface 32 from several attachment eyes 33 that is an integral part of the associated end wall 16 . 17 are and the outer peripheral surface 15 of the cylinder tube 13 protrude radially. These several attachment eyes 33 are about the longitudinal axis 3 distributed around, in particular in a uniform distribution. Exemplary are per attachment interface 32 a total of four attachment eyes 33 provided, which lie in the corners of an imaginary square.

Every attachment eye 33 has a mounting hole 34 , which is preferably formed axially continuous and in the example, a fastening screw is inserted.

The mounting hole 34 can have an integrally molded internal thread. There is also the possibility in the mounting hole 34 a separate internal thread member, such as a nut, rotatably insert. The internal thread element may for example be pressed or molded.

By a coordinated fluid loading of the two working chambers 24 . 25 can one on the drive piston 5 be generated in one direction or the other acting resultant force, which has the consequence that the drive unit 11, the drive movement 12 in one direction or the other. It may be an extension movement, in which the drive piston 5 to the first end wall 16 approaches and the piston rod 8th increasingly from the front of the cylinder housing 2 extending. It may also be a retraction movement in which the drive piston 5 to the second end wall 17 approaches and at the piston rod 8th increasingly in the cylinder housing 2 retracts. The drive movement 12 can take place between two Hubendlagen, which are defined by the fact that the drive piston 5 either at the first end wall 16 or at the second end wall 17 has come axially to the plant.

In an embodiment not shown, the working cylinder 1 of a so-called single-acting design. Here is the movement of the drive unit 11 only in one direction caused by controlled fluid loading and in the other direction, for example by a return spring.

During the drive movement 12 slides the drive piston 5 on the inner circumferential surface 14 of the cylinder tube 13 along. The inner peripheral surface 14 So forms a so-called tread for the drive piston 5 ,

Advantageously, there is the cylinder tube 13 in its entirety made of a carbon fiber reinforced plastic. This carbon fiber reinforced plastic also forms the tread for the drive piston 5 functioning inner peripheral surface 14 of the cylinder tube 13 , Appropriately, the cylinder tube 13 produced by injection molding.

The carbon fiber-reinforced plastic consists of a plastic matrix in which a large number of carbon fibers are embedded.

A synonymous term for "carbon" is "carbon". Thus, the material of the cylinder tube is a carbon fiber reinforced plastic with carbon fibers embedded in a plastic matrix.

As far as in this patent application of a carbon fiber reinforced plastic is mentioned, always a composite material is meant, which has a plastic matrix with embedded carbon fibers.

Preferably, there is also each end wall 16 . 17 Made of carbon fiber reinforced plastic. In this way, a uniform material cylinder housing 2 be realized. The production of carbon fiber reinforced plastic leads to a low weight with high structural rigidity and strength.

In a preferred embodiment of the cylinder housing 2 that corresponds to the illustrated embodiment is that of the piston rod 8th enforced first end wall 16 integral with the cylinder tube 13 designed so that these two components when assembling the working cylinder 1 uniformly manageable cylinder tube end wall assembly 35 form. The second end wall 17 however, as with respect to the cylinder tube 13 separate end cover 170 executed by fasteners 36 on the cylinder tube 13 is attached. Preferably, it is a non-detachable attachment, which applies to the illustrated embodiment. By way of example, the fastening means consist 36 from a welded joint, which is preferably an ultrasonic welded joint or a friction welded joint.

In the production of the working cylinder 1 become the cylinder end wall assembly 35 and the drive unit 11 made separately. Before then the end cap 170 is mounted, the drive unit 11 with the piston rod 8th ahead through the then still open front side of the housing interior 4 through into the housing interior 4 plugged in, so that the piston rod 8th through the guide hole 18 passes. Subsequently, the second end wall 17 attached and attached.

Preferably, the separate end cover 170 an axial centering extension 37 , which is in particular sleeve-shaped and its outer cross-sectional profile of the cross-sectional profile of the housing interior 4 corresponds so that it frontally into the cylinder tube 13 dips and the same with simultaneous centering 5 Fixed radially immovable. The fasteners 36 are preferably in the region of the centering process 37 ,

In a non-illustrated embodiment, the second end wall is 17 integral with the cylinder tube 13 trained while the first end wall 16 is designed as a separately attached end cover.

In a likewise not shown embodiment, both end walls 16 . 17 as with respect to the cylinder tube 13 separate end cover formed by suitable fasteners 36 on the cylinder tube 13 are fastened, in particular independently of each other and in particular in the above with reference to the end cover 170 described way.

The drive piston 5 expediently contains a particular rigidly formed and preferably one-piece piston body 38 , which is the adjoining piston rod 8th radially surmounted all around. Its outer diameter is greater than that of the coaxial subsequent piston rod 8th , The piston body 38 is preferably disc-shaped. The piston body 38 is in particular that part of the drive piston 5 , which is responsible for the stability of the drive piston 5 is responsible and the fluidic driving forces on the piston rod 8th transfers.

The drive piston is preferred 5 on its outer periphery with a radially outwardly facing, around the longitudinal axis 3 around extending piston guide surface 42 fitted. With this piston guide surface 42 is the drive piston 5 slidable on the inner peripheral surface 14 or running surface of the cylinder tube 13 at.

According to a preferred embodiment, apart from that in the section IIIb of 3 illustrated modification is implemented in all the illustrated embodiments, it is immediately the radially outwardly facing outer peripheral surface 43 of the piston body 38 holding the piston guide surface 42 forms. The piston body 38 So it supports directly with its outer peripheral surface 43 in a slidable manner radially on the inner peripheral surface 14 of the cylinder tube 13 from. In this context, it is particularly advantageous if the piston body 38 made of a carbon fiber reinforced plastic, so that the outer peripheral surface 43 made of this carbon fiber reinforced plastic. The effect is the same as above based on the cylinder tube 13 explained, namely that a Gleitflächenpaarung arises, which is a particularly low-friction drive movement 12 guaranteed.

It is best if both the cylinder tube 13 as well as the piston body 38 Made of carbon fiber reinforced plastic, since then a particularly good sliding behavior is achieved.

In the piston body 38 is expediently a radially outward to the outer peripheral surface 43 open annular groove 44 formed coaxially with the longitudinal axis 9 of the drive piston 5 and in particular the entire drive unit 11 is arranged. This ring groove 44 can remain empty and represent an unfilled cavity, for example, to achieve weight savings. An advantageous effect of the annular groove 44 It also exists in that the outer peripheral surface 43 in two axially spaced apart annular outer peripheral surface portions 43a . 43b is divided, what for the support and guidance of the drive piston 5 is advantageous if these outer peripheral surface portions 43a . 43b immediately the piston guide surface 42 form.

According to the section IIIa of 3 illustrated modification may be the annular groove 44 also as a recording groove 44a be formed, the at least one for detecting the position of the drive piston 5 or the entire drive unit 11 usable activation element 45 receives. This activation element 45 is, for example, annular and coaxial with the longitudinal axis 9 arranged.

The activation element 45 can with a particular in the region of the outer circumference of the cylinder tube 13 arranged to cooperate, not further illustrated in the drawing position detection device, which has, for example, one or more position sensors or a position measuring system. Depending on the type and functionality of the position detection device, the activation element has 45 for example via permanent magnetic or ferromagnetic properties.

The activation element 45 For example, in the injection molding of the piston body 38 in the piston body 38 be embedded, so that automatically the receiving groove 44a formed. But it is also possible a subsequent installation of the activation element 45 in the receiving groove 44a , For example, in that a slotted, resilient activation element 45 is used, which is in the context of a snap action in the receiving groove 44a can place.

In an unillustrated embodiment, in the piston body 38 no ring groove 44 educated.

The piston body 38 may have a ribbing, in particular to increase its stability yet.

Under certain circumstances and depending on the application, a sufficient Abdichtqualität between the drive piston 5 and the cylinder tube 13 be achieved without additional soft-sealing structures. With appropriate manufacturing accuracy, the gap between the inner peripheral surface can be 14 of the cylinder tube 13 and the outer peripheral surface 43 of the piston body 38 Keep so low that no detrimental leakage between the two working chambers 24 . 25 occurs.

In most applications, however, it will be advantageous if the drive piston 5 in addition to the rigid and made of a hard material piston body 38 via an annular piston seal 46 which consists of a rubber-elastic material, which is referred to in the following for simplification as elastomeric material. Such an embodiment is implemented in all illustrated embodiments. Here is the piston seal 46 preferably of an elastomeric structure 47 formed on the piston body 38 is attached, in particular by injection molding on the piston body 38 is applied. The production takes place in particular in a two-component injection molding process.

The piston seal 46 has one or more annular sealing portions 46a . 46b coaxial with the longitudinal axis 9 are arranged and the sliding on the inner peripheral surface 14 of the cylinder tube 13 issue.

The piston seal is preferred 46 in two annular sealing sections 46a . 46b split, which are arranged at an axial distance from each other and in the case of the presence of an annular groove 44 axially on both sides of this annular groove 44 on the piston body 38 are fixed.

For impact damping in the stroke end positions of the drive piston 5 preferably with at least one of a rubber elastic material impact damper 48 fitted. This is the case in the illustrated embodiment. Here is for each stroke direction of the drive unit 11 a crash cushion 48 present, in each case at one of the two mutually axially oppositely oriented end faces of the piston body 38 is arranged. Every impact absorber 48 preferably has one to the longitudinal axis 9 concentric ring structure. Preference is given to each impact damper 48 from several damper segments 52 together, in a particular regular distribution around the longitudinal axis 9 are placed around.

Preferred is each crash cushion 48 an integral part of the already mentioned elastomer structure 47 , The elastomer structure 47 preferably forms both the piston seal 46 as well as the at least one impact absorber 48 out. The recommended material is a thermoplastic elastomer. Alternatively, rubber, fluororubber (FKM) or other elastomers could be used.

According to one in the section IIIb of 3 Illustrated modification may be to form the piston guide surface 42 also with respect to the piston body 38 separate guide ring 53 as another component of the drive piston 5 to be available. This guide ring 53 has a lower wall thickness compared to its length, so you could call it a guide sleeve. He encloses the piston body 38 radially outward in a coaxial manner, preferably one in the piston body 38 trained annular groove 44 and an activation element possibly arranged therein 45 radially outside covers. The guide ring 53 For example, axially between the two above-mentioned annular sealing portions 46a . 46b be held.

One on a separate guide ring 53 dispensing embodiment has the great advantage that an activation element 45 leading to the inner peripheral surface 14 should be spaced, very close to this inner circumferential surface 14 can be brought up. As a result, a small distance to the external position detection device can be achieved, which favors the functional accuracy and in particular also creates the possibility to operate with magnetic fields of low intensity.

Inside the drive unit 11 are the piston body 38 and the piston rod 8th expediently to a one-piece piston-piston rod assembly 54 summarized, with both the piston body 38 as well as the piston rod 8th and hence the entire piston-body piston rod assembly 54 consist of a carbon fiber reinforced plastic. The piston body piston rod assembly 54 can be very process-reliable, very dimensionally stable and yet inexpensive to produce by an injection molding process.

Regarding the piston rod 8th The carbon-fiber-reinforced plastic not only has a weight-saving effect but also positively influences the sliding bearing of the piston rod 8th when passing through the first end wall 16 ,

The piston rod 8th lies with its outer peripheral surface 23 slidable on the guide bore 18 limiting piston rod guide surface 22 at. It arises between the outer peripheral surface 23 the piston rod 8th and the piston rod guide surface 22 a very low-friction contact, a particularly smooth and low-wear drive movement 12 allowed.

This effect can be further optimized when the guide bore 18 according to the illustrated embodiments - apart from the modification shown in section IIIc - directly from the existing of carbon fiber reinforced plastic first end wall 16 is defined. In other words, here is the guide hole 18 directly from a section of the one-piece first end wall 16 educated. According to the illustrated embodiment, the first end wall 16 an integrated sleeve-shaped section 55 have the guide bore 18 encloses. The term "bore" is related to the guide bore 18 not necessarily to be understood as a mechanically introduced bore, but quite generally as any bore-like opening, however it is made. Incidentally, the guide bore 18 expediently directly at the original formation of the associated first end wall 16 formed in particular by injection molding.

The piston rod 8th can also be designed as a so-called continuous piston rod, which at the same time through both end walls 16 . 17 extends through, then each of the end walls 16 . 17 with a piston rod guide surface 22 forming guide bore 18 is provided.

The of the piston rod 8th enforced first end wall 16 expediently also carries one to the longitudinal axis 3 Coaxially arranged piston rod seal 56 slidable on the outer peripheral surface 23 the piston rod 8th is applied. The piston rod seal 56 is suitably in one with the guide bore 18 coaxial receiving groove 57 the first end wall 16 fixed. The piston rod seal 56 seals the first end wall 16 subsequent first working chamber 24 in the passage area of the piston rod 8th towards the surroundings. Preferred is in the piston rod seal 56 also integrated a scraper function, the retracting piston rod 8th is effective and penetration of contaminants into the interior of the cylinder housing 2 prevented.

According to an embodiment not illustrated, a piston rod seal can be used 56 also be waived. The working cylinder is then formed piston rod seal.

According to the section IIIc of 3 illustrated embodiment, the guide bore 18 and the piston rod guide surface 22 also by referring to the first end wall 16 separate guide bush 58 be realized in the first end wall 16 is attached. The guide bush 58 is especially fixed by placing it in the first end wall 16 pressed or in the injection molding of the first end wall 16 has been encapsulated by the carbon fiber reinforced plastic. The guide bush 58 can be made of any suitable material. The guide bush 58 consists in particular of metal, so that a metal bearing of the piston rod 8th he follows. The above-mentioned piston rod seal 56 Can be made separately as shown or with the guide bush 58 be combined into a single unit.

The drive unit is preferred 11 formed hollow along part of its length. Coaxial through the drive unit 11 a cavity extends 62 , which is not continuously open, so by the drive unit 11 through no fluid connection between the housing interior 4 and the atmospheric environment of the cylinder housing 2 takes place.

The cavity 62 is by a preferred with the piston rod 8th one-piece partition 63 in two axially successive cavity sections 62a . 62b divided, which is an outer cavity portion 62a acts, the front side at the outer end portion 7 opens out, and to an inner cavity section 62b , which at the opposite, in the housing interior 4 located end face of the drive unit 11 opens. Preferably, the multi-part cavity extends 62 exclusively in the piston body-piston rod assembly 54 , While the outer cavity portion 62a exclusively in the piston rod 8th extends, the inner cavity portion extends 62b both in the piston rod 8th as well as through the piston body 38 therethrough. The partition 63 is expediently in the transition region between the Abgriffsabschnitt 6 , which is exemplified with an external thread, and the adjoining length of the piston rod 8th ,

The partition 63 could also be at another longitudinal position of the drive unit 11 be placed. You could, for example, directly to one of the two end faces of the piston-piston rod assembly 54 be provided.

According to an embodiment not illustrated, with axial distance to the dividing wall 63 another partition in the cavity 62 be arranged, in particular as a separate component in the cavity 62 used and preferably pressed. As a result, dead spaces can be reduced.

All previous explanations also apply to the in the 4 and 5 illustrated modified embodiment of a drive unit 11 a fluid operated working cylinder 1 , This in the 4 and 5 illustrated embodiment also makes it clear that in the piston rod 8th in one piece at least with respect to the drive piston 5 axially protruding buffering extension 64 . 65 can be integrated, for the realization of at least one fluidic end position damping device of the working cylinder 1 serves.

An example is the piston rod 8th two such Pufferungsfortsätze 64 . 65 from two lengths of an inner piston rod length 66 are formed, whose outer diameter is greater than that of a toward the outer end portion 7 subsequent outer piston rod longitudinal section 67 , The drive piston 5 sits at least substantially longitudinally on the inner piston rod longitudinal section 66 of which it is axially on both sides forming one of each Pufferungsfortsätze 64 . 65 is towered over. The optional inner cavity section 62b expediently extends continuously both along the inner piston rod longitudinal section 66 as well as along the outer piston rod longitudinal section 67 ,

Conveniently, the piston body 38 integral with the inner piston rod longitudinal section 66 formed.

Each buffering extension 64 . 65 is intended for operation of the working cylinder 1 to close at least partially a discharge cross section for the outflowing pressure medium when reaching a stroke end position, so that builds up a back pressure will, which slows down the drive movement 12 entails.

The buffering extensions 64 . 65 can be formed on their outer periphery depending on the damping principle smooth surface or with longitudinal grooves 68 be provided.

It is particularly advantageous if at the same time all components of the working cylinder 1 , which have been described in terms of the possibility of production from carbon fiber reinforced plastic, consist of this material, so that the working cylinder 1 at least as far as possible consists of this carbon fiber reinforced plastic. It is also advantageous to use the same carbon fiber reinforced plastic for all these components.

The plastic matrix of the carbon fiber-reinforced plastic preferably consists of a thermoplastic plastic material, in particular of a polyamide plastic material and expediently of polyamide 6 or polyamide 6.6 , Compared to a thermosetting plastic material that is likewise possible in principle, the thermoplastic material has the great advantage of being able to be processed by injection molding or extrusion, ie for use in production processes which are preferably used in the illustrated working cylinder. Also advantageous is a realization of the plastic matrix of partly aromatic or fully aromatic polyamide.

The carbon fibers embedded in the plastic matrix are preferably short fibers which have an extremely short fiber length, so that they can be processed very well in an injection molding or extrusion process, for example based on pellets. The fiber length is suitably in the range between 0.05 mm and 1 mm, and preferably in the range of 0.1 mm to 0.4 mm. As currently optimal, an average fiber length of 0.3 mm is considered.

The percentage by weight of the carbon fibers within the carbon fiber reinforced plastic is suitably between 5 and 60 weight percent. Preferably, the proportion of carbon fibers is in the range of 40% by weight.

Conveniently, all components of the working cylinder 1 made of a carbon fiber reinforced plastic with carbon fibers embedded in a plastic matrix, produced by injection molding.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 3703125 [0004]
• DE 10141560 C2 [0005]
• AT 298923 A [0006]
• DE 102010008349 A1 [0007]

Claims (22)

Drive unit for a fluid-operated working cylinder, with a drive piston (5) and a piston rod (8), the drive piston (5) having a piston rod (8) radially superior piston body (38) with the piston rod (8) to a plastic existing one-piece piston-body piston rod assembly (54) is summarized, characterized in that the piston body-piston rod assembly (54) including the piston body (38) and the piston rod (8) consists of a carbon fiber reinforced plastic with embedded in a plastic matrix carbon fibers. Drive unit to Claim 1 characterized in that the radially outwardly facing outer peripheral surface (43) of the piston body (38) is formed as a piston guide surface (42) for direct sliding radial support on the inner peripheral surface (14) of a cylinder tube (13) of a fluid operated working cylinder (1) is provided. Drive unit to Claim 1 or 2 , characterized in that in the piston body (38) to its radially outwardly facing outer peripheral surface (43) open towards annular groove (44) is formed, which expediently forms a receiving groove (44a) for a usable for detecting the position activation element (45). Drive unit according to one of Claims 1 to 3 characterized in that on the piston body (38) an elastomeric structure (47) is fixed, which forms a sealing and slidable abutment on the inner peripheral surface (14) of a cylinder tube (13) of the fluid operated working cylinder (1) piston seal (46) provided and which expediently also forms at least one impact damper (48) which is effective in a stroke end position of the drive piston (5). Drive unit according to one of Claims 1 to 4 , characterized in that in the piston rod (8) integrally at least one with respect to the drive piston (5) axially projecting, provided for a fluidic cushioning Pufferungsfortsatz (64, 65) is integrated and / or that the drive unit (11) over only a part of their Length is hollow. Fluid-actuated working cylinder, with a cylinder housing (2) defining a housing interior (4) in which a drive piston (5) of a piston rod (8) further comprising a drive unit (11) is arranged linearly displaceable, wherein the drive piston (5) one Piston rod (8) radially superior piston body (38), which is combined with the piston rod (8) to a one-piece plastic piston rod-piston rod assembly (54), characterized in that the piston-piston rod assembly (54) including of the piston body (38) and the piston rod (8) consists of a carbon fiber reinforced plastic with embedded in a plastic matrix carbon fibers. Working cylinder after Claim 6 , characterized in that the drive unit (11) according to the characterizing features of one of Claims 2 to 5 is trained. Working cylinder after Claim 6 or 7 , characterized in that the cylinder housing (2) has a housing inner space (4) peripherally delimiting cylinder tube (13), including its the housing interior (4) directly radially limiting inner peripheral surface (14) consists of a carbon fiber reinforced plastic with embedded in a plastic matrix carbon fibers , Working cylinder after Claim 8 , characterized in that the cylinder housing (2) on at least one end face of the cylinder tube (13) has a housing inner space (4) axially delimiting end wall (16, 17). Working cylinder after Claim 8 or 9 , characterized in that the cylinder housing (2) at both end faces of the cylinder tube (13) each one the housing interior (4) axially delimiting end wall (16, 17), wherein at least one of the end walls (16, 17) of the piston rod (8 ) is slidably interspersed. Working cylinder after Claim 10 , characterized in that from the piston rod (8) slidably penetrated end wall (16, 17) has a guide bore (18) through which the piston rod (8) extends through and the inner circumference of a piston rod (8) radially supporting piston rod Guide surface (22) forms. Working cylinder after Claim 11 , characterized in that the guide bore (18) is defined directly by the associated end wall (16, 17), wherein the piston rod guide surface (22) made of a carbon fiber reinforced plastic of the end wall (16, 17) is formed. Working cylinder after one of the Claims 9 to 12 , characterized in that at least one end wall (16, 17) of the cylinder housing (2) is formed integrally with the cylinder tube (13). Working cylinder after Claim 13 in conjunction with one of Claims 10 to 12 , characterized in that the by the piston rod (8) slidably penetrated end wall (16, 17) is formed integrally with the cylinder tube (13). Working cylinder after one of the Claims 9 to 14 , characterized in that at least one and expediently each end wall (16, 17) consists of a carbon fiber reinforced plastic with carbon fibers embedded in a plastic matrix. Working cylinder after one of the Claims 9 to 15 characterized in that at least one end wall (16, 17) of the cylinder housing (2) is formed with respect to the cylinder tube (13) as a separate end cover (170) secured by fastener means (36) to the cylinder tube (13) Fastening means (36) expediently consist of a welded connection, in particular an ultrasonic welded connection or a friction-welded connection. Working cylinder after one of the Claims 9 to 16 , characterized in that at least one end wall (16, 17) of the cylinder housing (2) from a in the housing interior (4) opening fluid passage (26, 27) is interspersed. Drive unit according to one of Claims 1 to 5 and / or working cylinder according to one of Claims 6 to 17 , characterized in that the carbon fibers are short fibers whose fiber length is suitably in the range of 0.05 mm to 1 mm and preferably in the range of 0.1 mm to 0.4 mm, and / or that the proportion the carbon fiber in the carbon fiber reinforced plastic is between 5 and 60 weight percent, and is preferably 40 weight percent. Drive unit according to one of Claims 1 to 5 or 18 and / or working cylinder according to one of Claims 6 to 18 , characterized in that the plastic matrix consists of a thermoplastic plastic material, expediently of a polyamide plastic material, or that the plastic matrix consists of partly aromatic or fully aromatic polyamide. Drive unit according to one of Claims 1 to 5 . 18 or 19 and / or working cylinder according to one of Claims 6 to 19 Characterized in that at least composed of a carbon fiber reinforced plastic with embedded in a plastic matrix carbon fibers piston body and piston rod assembly (54) and expediently each consisting of this material component is an injection molded part. Method for producing a drive unit according to one of Claims 1 to 5 and 18 to 20 and / or a fluid-operated working cylinder according to one of Claims 6 to 20 , characterized in that at least the piston body-piston rod assembly (54) consisting of a carbon fiber-reinforced plastic with carbon fibers embedded in a plastic matrix is produced by injection molding. Method according to Claim 21 , characterized in that all of a carbon fiber reinforced plastic with embedded in a plastic matrix carbon fibers components of the working cylinder (1) are produced by injection molding.

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