EP1336756B1 - Pump piston filled with hollow spheres - Google Patents

Pump piston filled with hollow spheres Download PDF

Info

Publication number
EP1336756B1
EP1336756B1 EP20030001458 EP03001458A EP1336756B1 EP 1336756 B1 EP1336756 B1 EP 1336756B1 EP 20030001458 EP20030001458 EP 20030001458 EP 03001458 A EP03001458 A EP 03001458A EP 1336756 B1 EP1336756 B1 EP 1336756B1
Authority
EP
European Patent Office
Prior art keywords
hollow piston
hollow
filling
piston according
spheres
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
EP20030001458
Other languages
German (de)
French (fr)
Other versions
EP1336756A2 (en
EP1336756A3 (en
Inventor
Bernd Gärtner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Brueninghaus Hydromatik GmbH
Original Assignee
Brueninghaus Hydromatik GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Brueninghaus Hydromatik GmbH filed Critical Brueninghaus Hydromatik GmbH
Publication of EP1336756A2 publication Critical patent/EP1336756A2/en
Publication of EP1336756A3 publication Critical patent/EP1336756A3/en
Application granted granted Critical
Publication of EP1336756B1 publication Critical patent/EP1336756B1/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B1/00—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders
    • F04B1/12—Multi-cylinder machines or pumps characterised by number or arrangement of cylinders having cylinder axes coaxial with, or parallel or inclined to, main shaft axis
    • F04B1/122—Details or component parts, e.g. valves, sealings or lubrication means
    • F04B1/124—Pistons

Definitions

  • the invention relates to a hollow piston for a piston engine, in particular an axial piston machine, according to the preamble of claim 1 and a method for producing such a hollow piston.
  • a piston for an axial piston machine which is designed as a hollow body, in which an insert used and by means of an outer end surface cross-envelope of the insert surrounding the wall of the hollow body is axially secured.
  • the envelope is formed by pressing in the longer than finally sized wall of the hollow body in a plurality of mutually opposite recesses or in an annular recess of the insert and cutting the piston thus formed approximately in the region of the recesses or the annular recess.
  • the insert is preferably made of aluminum.
  • a disadvantage of the known from DE 39 19 329 A1 piston is that the insert is made of a different material than the hollow body of the piston, so that subsequent In particular, thermal processing steps due to the different thermal expansion are limited feasible. Furthermore, the insert must be made in register to minimize imbalance and dead volume, which places a high demand on the manufacturing process.
  • the different methods of locking the piston such as the envelope in the document mentioned with pressed-in recess or the welding with a lid, often result in large dead volumes.
  • DE 199 29 760 A1 discloses a process for producing metallic, oxidic or ceramic hollow spheres in which starting materials for the cladding layer are applied to moving spherical carrier elements and the green compacts thus produced are subsequently pyrolyzed and sintered.
  • the spherical support elements are set in motion and applied a liquid to pasty binder. Separately, at least one dry, powdered or granular starting material is fed to form the coating layer. Subsequently, the green compacts are sintered substantially in static rest, wherein the material of the support elements is pyrolyzed before completion of the sintering.
  • the invention has for its object to provide a hollow piston, which on the one hand has a reduced mass relative to a mass piston and on the other hand, a high strength and to provide a method for producing such hollow piston.
  • the object is with respect to the hollow piston by the features of claim 1 and with respect to Manufacturing method solved by the features of claim 24.
  • the hollow piston can be designed both in a construction with an integrally formed ball joint and in inverse construction with a ball joint used in a camp.
  • the bearing can be integrally connected to the hollow piston or inserted as a separate component in this.
  • the latter embodiment is particularly advantageous because the hollow piston is thereby produced inexpensively from a simple piece of pipe.
  • a further advantage is that the hollow piston can be left open depending on the An Crumissen at its fillable end or can be provided to reduce the dead volume or increase the stability with a lid.
  • a passage of the hydraulic fluid through a pipe can be realized in a dense ball packing with very low dead volume in a simple manner.
  • FIGS. 1 to 3 are particularly suitable for use in axial piston machines.
  • Such axial piston machine can be carried out, for example, in swash plate design with adjustable displacement and includes in a known manner as essential components a hollow cylindrical housing, a terminal block attached to the housing, a swash plate, a control body, a drive shaft and a cylinder drum.
  • cylinder drum In the cylinder drum cylinder bores are radially distributed evenly.
  • the hollow piston described in more detail in FIGS. 1 and 2 are arranged axially displaceable, with the rod ends of the hollow pistons formed as ball heads in FIGS. 1A to 1C being supported by sliding shoes on the swashplate.
  • the hollow piston can also be embodied in an inverse construction, as shown in FIGS. 2A to 2E, wherein the sliding blocks wear the ball heads formed as joint heads and engage with them in corresponding bearings of the hollow piston.
  • the pistons are designed as a hollow piston and provided with a suitable core, which may be made of aluminum, for example.
  • the core serves on the one hand the weight savings and on the other hand the stabilization of the hollow piston.
  • the disadvantages of such completely or partially filled by a core hollow piston are many. In addition to the increased production costs and the resulting costs, in particular the dead volume, which remains in the production of the piston, the production of a central bore and the closure of the hollow piston with the required process techniques and processing steps of disadvantage.
  • the hollow piston 1 as shown in FIGS. 1 to 3, provided with a hollow ball filling 2 to minimize the hollow space remaining in the hollow piston 1 1 or the dead volume to reduce the mass of the hollow piston 1 with respect to a solid piston and still to achieve a high stability of the hollow piston 1.
  • the hollow ball filling 2 allows the passage of the hydraulic fluid without the need for a hollow piston 1 continuous bore. If the same material as for the hollow piston 1 is used for the hollow sphere filling 2, further processing, for example with heat treatment, is also possible in a simple manner following the filling, since both the hollow piston 1 and the hollow sphere filling 2 are made of the same material and thus subject to the same thermal expansion.
  • the production of the hollow piston 1 with the hollow sphere filling 2 takes place according to the invention in several steps.
  • the hollow piston 1 is produced in a known manner, for example by turning.
  • the individual hollow spheres 4 can be either already sintered or sintered in a further production step in the hollow piston 1 together with this optionally under additional pressure to a solid diffusion bond between the main body the hollow piston 1, the hollow balls 4 and a possibly aufdin cover 5 produce.
  • the individual hollow balls 4 can also be connected by gluing or soldering.
  • the individual hollow balls 4 are, as already described above, z. B. produced by a powder metallurgy process.
  • substrate materials such. B. Styropor® sprayed by spin coating in a continuous stream of hot air with a binder metal powder suspension and then either in the form of individual balls or in a composite heat treated.
  • pyrolysis of the styrofoam core and of the binder or sintering of the metal powder takes place, as a result of which hollow spherical molded bodies or metallic single hollow spheres 4 are formed.
  • the individual hollow balls 4, which are in a simple manner in the hollow piston 1 can be introduced.
  • Typical dimensions of the hollow balls 4 are diameters of about 0.5 mm to 10 mm and wall thicknesses of about 20 microns to 1000 microns.
  • the diameter and the wall thickness of the hollow balls 4 can be chosen freely according to the high pressure requirements.
  • FIGS. 1A to 1C show hollow pistons 1 for a reciprocating machine manufactured according to the above-mentioned method as described above.
  • the hollow piston 1 are designed in a conventional manner, d. H. formed as ball joints rod ends 6 of the hollow piston 1 are based on sliding blocks on the swash plate of the axial piston from.
  • FIG. 1A shows the simplest variant of a hollow piston 1 according to the invention.
  • the hollow piston 1 comprises a main body 7, which has a recess 8 extending over at least part of the axial length of the main body 7.
  • the recess 8 can be produced in a conventional manner by means of cutting or non-cutting methods.
  • the condyle 6 is formed, which has a bore 9 through which flows the hydraulic fluid to the shoe for the purpose of lubrication and hydrostatic discharge.
  • the hollow balls 4 of the hollow sphere filling 2 are now filled into the recess 8 of the hollow piston 1 and, after appropriate compression by means of sintering, soldering or gluing together and connected to the hollow piston 1.
  • the hydraulic fluid flowing through the hollow piston 1 has enough space between the individual hollow spheres 4 to form the sliding shoe to stream.
  • the dead volume of the hollow piston 1 is the sum of all remaining between the hollow balls 4 cavities third
  • Fig. 1A The advantage of the embodiment shown in Fig. 1A is in particular the simple and thus cost manufacturability.
  • a second embodiment of a hollow piston 1 is shown in a conventional construction.
  • a cover 5 is used in this embodiment after filling the hollow piston 1 with hollow balls 4, which closes the hollow piston 1.
  • a bore 10 is formed, which allows the hydraulic fluid to flow into the recess 8 of the hollow piston 1.
  • the hollow piston 1 is sintered. This results in a hollow piston 1 with a very low dead volume, high stability and compared to a solid piston significantly reduced mass.
  • the hydraulic fluid flows as in the previous embodiment through the remaining cavities 3 between the hollow balls 4th
  • FIG. 1C shows a further embodiment of a hollow piston 1 designed according to the invention. Since it may be possible in some situations that due to the too small size of the cavities 3 between the hollow spheres 4, the hydraulic fluid can no longer flow through the hollow piston 1 sufficiently unthrottled,
  • a central through-bore 11 may be provided in a tube 12 inserted in the hollow piston i.
  • the filling of the hollow piston 1 with hollow balls 4 is then carried out accordingly around the tube 8 around.
  • the hollow piston 1 is sintered to the connection between the individual components with each other, the hollow balls 4 with each other and between the hollow balls 4 and to achieve the said components.
  • the tube 12 can optionally pass through the lid 5 through a recess 13 as shown in Fig. 1C or the lid 5 and the tube 12 can be made in one piece with the inclusion of the bore 10.
  • the effective reduction of the dead volume and the high stability of the hollow piston 1 are particularly advantageous.
  • FIGS. 2A to 2E show embodiments for the inverse embodiment of the hollow piston 1, in which formed as ball joints rod ends 6 with sliding shoes 14 which are supported on the swash plate of the axial piston machine, for example, integrally formed and in a bearing 15 in the main body. 7 the hollow piston 1 pivotally engage.
  • the rod ends 6 also have a bore 9 for fluid line.
  • Fig. 2A a simple embodiment is shown, which has the advantage of simple and inexpensive to manufacture.
  • the hollow sphere filling 2 is introduced into the recess 8 of the hollow piston 1.
  • the hollow piston 1 is sintered to produce the required connection between the individual hollow balls 4 and the hollow piston 1.
  • the condyle 6 of the shoe 14 is inserted into the bearing 15.
  • the hydraulic fluid flows around the cavities 3 between the hollow spheres 4.
  • a lid 16 may be sintered, which also has a bore 17 for fluid line having.
  • FIG. 2C A similar simple embodiment as in Fig. 2 A is shown in Fig. 2C, where the bearing 15 is closed against the hollow piston 1.
  • This shape of the hollow piston 1 must also be provided with a bore 17 for fluid conduction into the recess 8 of the hollow piston 1. The filling of the hollow piston 1 is thereby possible from the opposite side with subsequent sintering as in Fig. 1A.
  • FIG. 2D has, analogously to FIG. 1B, a cover 5 with a bore 10, which is used to reduce the dead volume after filling the hollow piston 1 with hollow balls 4 in the hollow piston 1 and then connected by sintering to the hollow piston 1 and the hollow balls 4 becomes.
  • a tube 12 is arranged with a through-bore 11 through which the hydraulic fluid flows to the sliding shoe for the purpose of lubrication and hydrostatic discharge.
  • the hollow balls 4 are again smaller and filled so that they form after sintering with the tube 12, the lid 5 and the hollow piston 1 and one another with each other.
  • FIGS. 3A to 3C show further exemplary embodiments of hollow piston 1 configured in accordance with the invention in an inverse design.
  • the embodiments are to be seen in analogy to the embodiments shown in FIGS. 2C to 2E, wherein in the embodiments described below, the wall of the main body 7 is formed from a piece of pipe and one in Figs. 2C to 2E integral with the main body formed of the hollow piston 1 bearing sleeve 18 is formed as a separate component.
  • the bearing sleeve 18 also has a bore 17.
  • the connection between the main body 7 and the bearing sleeve 18 can be made by sintering as in the other components.
  • Advantage of the separate bearing sleeve is in particular the ease of manufacture of the main body 7 of a piece of pipe, which is particularly inexpensive.

Description

Die Erfindung betrifft einen Hohlkolben für eine Kolbenmaschine, insbesondere eine Axialkolbenmaschine, nach dem Oberbegriff des Anspruchs 1 und ein Verfahren zur Herstellung eines solchen Hohlkolbens.The invention relates to a hollow piston for a piston engine, in particular an axial piston machine, according to the preamble of claim 1 and a method for producing such a hollow piston.

Die bei Axialkolbenmaschinen früher eingesetzten Massivkolben setzten einem Betrieb bei höheren Drehzahlen Grenzen. Bei höheren Drehzahlen ergeben sich Festigkeitsprobleme für die Zylinder und für die Kolben-Rückhalteeinrichtung aufgrund der hohen auftretenden Flieh- und Massenkräfte sowie thermische Probleme an den Berührungsflächen zwischen Kolben und Zylinder aufgrund der aus den Fliehkräften resultierenden Reibungskräfte. Um Axialkolbenmaschinen mit erhöhter Drehzahl betreiben zu können, werden daher Hohlkolben mit leichten Füllstücken eingesetzt.The solid pistons formerly used in axial piston machines set limits to operation at higher speeds. At higher speeds, strength problems for the cylinders and for the piston retainer arise due to the high centrifugal and mass forces that occur, as well as thermal problems at the contact surfaces between the piston and cylinder due to the frictional forces resulting from the centrifugal forces. In order to operate axial piston machines with increased speed, hollow pistons with light filler pieces are therefore used.

Beispielsweise ist aus der DE 39 19 329 A1 ein Kolben für eine Axialkolbenmaschine bekannt, welcher als Hohlkörper ausgebildet ist, in den ein Einsatzstück eingesetzt und mittels eines dessen äußere Stirnfläche übergreifenden Umschlags der das Einsatzstück umgebenden Wand des Hohlkörpers axial gesichert ist. Dabei ist der Umschlag durch Einpressen der länger als endgültig bemessenen Wand des Hohlkörpers in mehrere einander gegenüberliegende Ausnehmungen oder in eine Ringausnehmung des Einsatzstückes und Ablängen des so gestalteten Kolbens etwa im Bereich der Ausnehmungen oder der Ringausnehmung gebildet. Das Einsatzstück ist dabei vorzugsweise aus Aluminium hergestellt.For example, from DE 39 19 329 A1 a piston for an axial piston machine is known, which is designed as a hollow body, in which an insert used and by means of an outer end surface cross-envelope of the insert surrounding the wall of the hollow body is axially secured. In this case, the envelope is formed by pressing in the longer than finally sized wall of the hollow body in a plurality of mutually opposite recesses or in an annular recess of the insert and cutting the piston thus formed approximately in the region of the recesses or the annular recess. The insert is preferably made of aluminum.

Nachteilig an dem aus der DE 39 19 329 A1 bekannten Kolben ist dabei, daß das Einsatzstück aus einem anderen Material als der Hohlkörper des Kolbens besteht, so daß nachfolgende insbesondere thermische Bearbeitungsschritte bedingt durch die unterschiedliche Wärmeausdehnung nur begrenzt durchführbar sind. Weiterhin muß daß Einsatzstück paßgenau gefertigt sein, um Unwucht und Totvolumen zu minimieren, was eine hohe Anforderung an die Fertigungsverfahren stellt. Die unterschiedlichen Verfahren zum Abschließen des Kolbens wie der in der vorliegenden Druckschrift angeführte Umschlag mit eingepreßter Ausnehmung oder auch das Verschweißen mit einem Deckel lassen oftmals große Totvolumina entstehen.A disadvantage of the known from DE 39 19 329 A1 piston is that the insert is made of a different material than the hollow body of the piston, so that subsequent In particular, thermal processing steps due to the different thermal expansion are limited feasible. Furthermore, the insert must be made in register to minimize imbalance and dead volume, which places a high demand on the manufacturing process. The different methods of locking the piston, such as the envelope in the document mentioned with pressed-in recess or the welding with a lid, often result in large dead volumes.

Zwar ist aus der DE 199 29 760 A1 ein Verfahren zur Herstellung metallischer, oxydischer oder keramischer Hohlkugeln bekannt, bei welchem Ausgangsstoffe für die Hüllschicht auf bewegte kugelförmige Trägerelemente aufgebracht und die so hergestellten Grünlinge nachfolgend pyrolisiert und gesintert werden. Dabei werden die kugelförmigen Trägerelemente in Bewegung versetzt und ein flüssiges bis pastöses Bindemittel aufgebracht. Gesondert wird mindestens ein trockener, pulver- oder granulatförmiger Ausgangsstoff zur Ausbildung der Hüllschicht zugeführt. Nachfolgend werden die Grünlinge im wesentlichen in statischer Ruhe gesintert, wobei das Material der Trägerelemente vor Abschluß der Sinterung pyrolisiert wird.Although DE 199 29 760 A1 discloses a process for producing metallic, oxidic or ceramic hollow spheres in which starting materials for the cladding layer are applied to moving spherical carrier elements and the green compacts thus produced are subsequently pyrolyzed and sintered. The spherical support elements are set in motion and applied a liquid to pasty binder. Separately, at least one dry, powdered or granular starting material is fed to form the coating layer. Subsequently, the green compacts are sintered substantially in static rest, wherein the material of the support elements is pyrolyzed before completion of the sintering.

Die Verwendung der mittels dem in der DE 199 29 760 A1 beschriebenen Verfahren hergestellten Hohlkugeln zum Befüllen von Hohlkolben für Kolbenmaschinen ist dort jedoch nicht beschrieben und wird durch diese Druckschrift auch nicht angeregt.However, the use of the hollow balls produced by means of the method described in DE 199 29 760 A1 for filling hollow pistons for piston engines is not described there and is not excited by this document.

Der Erfindung liegt die Aufgabe zugrunde, einen Hohlkolben zu schaffen, welcher einerseits eine gegenüber einem Massivkolben reduzierte Masse und andererseits eine hohe Festigkeit aufweist und ein Verfahren zur Herstellung solcher Hohlkolben anzugeben.The invention has for its object to provide a hollow piston, which on the one hand has a reduced mass relative to a mass piston and on the other hand, a high strength and to provide a method for producing such hollow piston.

Die Aufgabe wird bezüglich des Hohlkolbens durch die Merkmale des Anspruchs 1 und bezüglich des Herstellungsverfahrens durch die Merkmale des Anspruchs 24 gelöst.The object is with respect to the hollow piston by the features of claim 1 and with respect to Manufacturing method solved by the features of claim 24.

Vorteilhafte Weiterbildungen des erfindungsgemäß ausgestalteten Kolbens und des erfindungsgemäßen Verfahrens sind in den Unteransprüchen beschrieben.Advantageous developments of the inventively designed piston and the method according to the invention are described in the subclaims.

Der Hohlkolben kann sowohl in einer Bauweise mit einer angeformten Gelenkkugel als auch in inverser Bauweise mit einer in ein Lager eingesetzten Gelenkkugel ausgeführt sein.The hollow piston can be designed both in a construction with an integrally formed ball joint and in inverse construction with a ball joint used in a camp.

Das Lager kann dabei einstückig mit dem Hohlkolben verbunden oder als separates Bauteil in diesen eingeschoben sein. Letztere Ausführungsform ist besonders vorteilhaft, weil der Hohlkolben dadurch aus einem einfachen Rohrstück kostengünstig herstellbar ist.The bearing can be integrally connected to the hollow piston or inserted as a separate component in this. The latter embodiment is particularly advantageous because the hollow piston is thereby produced inexpensively from a simple piece of pipe.

Weiterhin ist von Vorteil, daß der Hohlkolben je nach den Anfordernissen an seinem befüllbaren Ende offen gelassen werden kann oder auch zur Verringerung des Totvolumens oder Erhöhung der Stabilität mit einem Deckel versehen sein kann.A further advantage is that the hollow piston can be left open depending on the Anfordernissen at its fillable end or can be provided to reduce the dead volume or increase the stability with a lid.

Auch eine Durchführung des Hydraulikfluids durch ein Rohr kann bei dichter Kugelpackung mit sehr geringem Totvolumen in einfacher Weise realisiert werden.Also, a passage of the hydraulic fluid through a pipe can be realized in a dense ball packing with very low dead volume in a simple manner.

Besonders vorteilhaft ist die einfache Herstellbarkeit durch das erfindungsgemäße Verfahren.Particularly advantageous is the ease of manufacture by the inventive method.

Die Erfindung wird nachfolgend anhand von bevorzugten Ausführungsbeispielen und der Darstellung der sich gegenüber dem Stand der Technik ergebenden Vorteile anhand der Zeichnung näher erläutert. Es zeigen:

Fig. 1A-C
Ausführungsbeispiele erfindungsgemäßer Hohlkolben in konventioneller Bauweise;
Fig. 2A-E
Ausführungsbeispiele erfindungsgemäßer Hohlkolben in inverser Bauweise; und
Fig. 3A-C
Ausführungsbeispiele erfindungsgemäßer Hohlkolben in inverser Bauweise mit einer Wandung aus einem Rohrstück.
The invention will be explained in more detail with reference to preferred embodiments and the representation of the advantages compared with the prior art advantages with reference to the drawing. Show it:
Fig. 1A-C
Embodiments of inventive hollow piston in conventional design;
Fig. 2A-E
Embodiments of inventive hollow piston in inverse construction; and
Fig. 3A-C
Embodiments of inventive hollow piston in inverse construction with a wall of a piece of pipe.

Die in den Fig. 1 bis 3 dargestellten erfindungsgemäßen Ausführungsbeispiele von Hohlkolben sind insbesondere zur Anwendung in Axialkolbenmaschinen geeignet. Eine derartige Axialkolbenmaschine kann dabei beispielsweise in Schrägscheibenbauweise mit verstellbarem Verdrängungsvolumen ausgeführt sein und umfaßt in bekannter Weise als wesentliche Bauteile ein hohlzylindrisches Gehäuse, einen am Gehäuse befestigten Anschlußblock, eine Schrägscheibe, einen Steuerkörper, eine Triebwelle und eine Zylindertrommel. In der Zylindertrommel sind Zylinderbohrungen radial gleichmäßig verteilt angeordnet. In den Zylinderbohrungen sind die in den Fig. 1 und 2 näher beschriebenen Hohlkolben axial verschiebbar angeordnet, wobei sich die in den Fig. 1A bis 1C als Kugelköpfe ausgebildeten Gelenkköpfe der Hohlkolben über Gleitschuhe an der Schrägscheibe abstützen. Die Hohlkolben können jedoch auch in inverser Bauweise ausgeführt sein, wie in den Fig. 2A bis 2E dargestellt, wobei die Gleitschuhe die als Kugelköpfe ausgebildeten Gelenkköpfe tragen und mit diesen in entsprechende Lager der Hohlkolben eingreifen.The embodiments of hollow piston according to the invention shown in FIGS. 1 to 3 are particularly suitable for use in axial piston machines. Such axial piston machine can be carried out, for example, in swash plate design with adjustable displacement and includes in a known manner as essential components a hollow cylindrical housing, a terminal block attached to the housing, a swash plate, a control body, a drive shaft and a cylinder drum. In the cylinder drum cylinder bores are radially distributed evenly. In the cylinder bores, the hollow piston described in more detail in FIGS. 1 and 2 are arranged axially displaceable, with the rod ends of the hollow pistons formed as ball heads in FIGS. 1A to 1C being supported by sliding shoes on the swashplate. However, the hollow piston can also be embodied in an inverse construction, as shown in FIGS. 2A to 2E, wherein the sliding blocks wear the ball heads formed as joint heads and engage with them in corresponding bearings of the hollow piston.

Um die Axialkolbenmaschinen mit höherer Drehzahl betreiben zu können, werden die Kolben als Hohlkolben ausgeführt und mit einem geeigneten Kern versehen, welcher beispielsweise aus Aluminium gefertigt sein kann. Der Kern dient dabei einerseits der Gewichtsersparnis und andererseits der Stabilisierung des Hohlkolbens. Die Nachteile solcher ganz oder teilweise durch einen Kern ausgefüllten Hohlkolben sind vielfältig. Neben dem erhöhten Fertigungsaufwand und den dadurch entstehenden Kosten sind insbesondere das Totvolumen, welches fertigungstechnisch im Kolben verbleibt, die Herstellung einer zentralen Bohrung sowie der Verschluß des Hohlkolbens mit den dazu benötigten Verfahrenstechniken und Bearbeitungsschritten von Nachteil.In order to operate the axial piston machines at a higher speed, the pistons are designed as a hollow piston and provided with a suitable core, which may be made of aluminum, for example. The core serves on the one hand the weight savings and on the other hand the stabilization of the hollow piston. The disadvantages of such completely or partially filled by a core hollow piston are many. In addition to the increased production costs and the resulting costs, in particular the dead volume, which remains in the production of the piston, the production of a central bore and the closure of the hollow piston with the required process techniques and processing steps of disadvantage.

Erfindungsgemäß wird daher der Hohlkolben 1, wie in den Fig. 1 bis 3 dargestellt, mit einer Hohlkugelfüllung 2 versehen, um die im Hohlkolben 1 verbleibenden Hohlräume 3 bzw. das Totvolumen zu minimieren, die Masse des Hohlkolbens 1 gegenüber einem Massivkolben zu verringern und trotzdem eine hohe Stabilität des Hohlkolbens 1 zu erreichen. Weiterhin ermöglicht die Hohlkugelfüllung 2 den Durchgang des Hydraulikfluids ohne die Notwendigkeit einer den Hohlkolben 1 durchlaufenden Bohrung. Wird für die Hohlkugelfüllung 2 das gleiche Material wie für den Hohlkolben 1 verwendet, ist außerdem im Anschluß an die Füllung eine Weiterverarbeitung beispielsweise mit Wärmebehandlung in einfacher Weise möglich, da sowohl der Hohlkolben 1 als auch die Hohlkugelfüllung 2 aus dem gleichen Material gefertigt sind und somit gleicher Wärmedehnung unterliegen.According to the invention, therefore, the hollow piston 1, as shown in FIGS. 1 to 3, provided with a hollow ball filling 2 to minimize the hollow space remaining in the hollow piston 1 1 or the dead volume to reduce the mass of the hollow piston 1 with respect to a solid piston and still to achieve a high stability of the hollow piston 1. Furthermore, the hollow ball filling 2 allows the passage of the hydraulic fluid without the need for a hollow piston 1 continuous bore. If the same material as for the hollow piston 1 is used for the hollow sphere filling 2, further processing, for example with heat treatment, is also possible in a simple manner following the filling, since both the hollow piston 1 and the hollow sphere filling 2 are made of the same material and thus subject to the same thermal expansion.

Die Herstellung der Hohlkolben 1 mit der Hohlkugelfüllung 2 erfolgt dabei erfindungsgemäß in mehreren Schritten. Zunächst wird der Hohlkolben 1 in bekannter Weise hergestellt, beispielsweise durch Drehen. Danach erfolgt die Befüllung mit der aus einzelnen Hohlkugeln 4 bestehenden Hohlkugelfüllung 2. Die einzelnen Hohlkugeln 4 können dabei entweder bereits gesintert sein oder in einem weiteren Herstellungsschritt in dem Hohlkolben 1 gemeinsam mit diesem gegebenenfalls unter zusätzlichem Druck gesintert werden, um eine feste Diffusionsverbindung zwischen dem Hauptkörper des Hohlkolbens 1, den Hohlkugeln 4 und einem eventuell aufzusetzenden Deckel 5 herzustellen. Alternativ können die einzelnen Hohlkugeln 4 auch durch Kleben oder Verlöten verbunden werden.The production of the hollow piston 1 with the hollow sphere filling 2 takes place according to the invention in several steps. First, the hollow piston 1 is produced in a known manner, for example by turning. The individual hollow spheres 4 can be either already sintered or sintered in a further production step in the hollow piston 1 together with this optionally under additional pressure to a solid diffusion bond between the main body the hollow piston 1, the hollow balls 4 and a possibly aufzusetzenden cover 5 produce. Alternatively, the individual hollow balls 4 can also be connected by gluing or soldering.

Die einzelnen Hohlkugeln 4 werden dabei, wie bereits weiter oben beschrieben, z. B. durch ein pulvermetallurgisches Verfahren hergestellt. Hierbei werden Substratmaterialien wie z. B. Styropor® mittels Wirbelbeschichtung in einem kontinuierlichen Warmluftstrom mit einer Binder-Metallpulversuspension besprüht und anschließend entweder in Form von einzelnen Kugeln oder in einem Verbund wärmebehandelt. Dabei findet eine Pyrolyse des Styroporkerns und des Binders bzw. eine Versinterung des Metallpulvers statt, wodurch Hohlkugelformkörper oder metallische Einzel-Hohlkugeln 4 entstehen. Für die Befüllung der Hohlkolben 1 eignen sich insbesondere die Einzel-Hohlkugeln 4, welche in einfacher Weise in die Hohlkolben 1 einbringbar sind.The individual hollow balls 4 are, as already described above, z. B. produced by a powder metallurgy process. In this case, substrate materials such. B. Styropor® sprayed by spin coating in a continuous stream of hot air with a binder metal powder suspension and then either in the form of individual balls or in a composite heat treated. In this case, pyrolysis of the styrofoam core and of the binder or sintering of the metal powder takes place, as a result of which hollow spherical molded bodies or metallic single hollow spheres 4 are formed. For the filling of the hollow piston 1, in particular, the individual hollow balls 4, which are in a simple manner in the hollow piston 1 can be introduced.

Typische Abmessungen der Hohlkugeln 4 sind dabei Durchmesser von ca. 0,5 mm bis 10 mm und Wandstärken von ca. 20 µm bis 1000 µm. Der Durchmesser und die Wandstärke der Hohlkugeln 4 können dabei gemäß den Hochdruck-Anforderungen frei gewählt werden.Typical dimensions of the hollow balls 4 are diameters of about 0.5 mm to 10 mm and wall thicknesses of about 20 microns to 1000 microns. The diameter and the wall thickness of the hollow balls 4 can be chosen freely according to the high pressure requirements.

Die Fig. 1A bis 1C zeigen gemäß dem oben genannten Verfahren hergestellte Hohlkolben 1 für eine Kolbenmaschine wie oben beschrieben. Die Hohlkolben 1 sind dabei in konventioneller Weise ausgeführt, d. h. als Kugelköpfe ausgebildete Gelenkköpfe 6 der Hohlkolben 1 stützen sich über Gleitschuhe an der Schrägscheibe der Axialkolbenmaschine ab.FIGS. 1A to 1C show hollow pistons 1 for a reciprocating machine manufactured according to the above-mentioned method as described above. The hollow piston 1 are designed in a conventional manner, d. H. formed as ball joints rod ends 6 of the hollow piston 1 are based on sliding blocks on the swash plate of the axial piston from.

Das in Fig. 1A dargestellte Ausführungsbeispiel zeigt dabei die einfachste Variante eines erfindungsgemäßen Hohlkolbens 1. Der Hohlkolben 1 umfaßt einen Hauptkörper 7, welcher eine sich zumindest über einen Teil der axialen Länge des Hauptkörpers 7 erstreckende Ausnehmung 8 aufweist. Die Ausnehmung 8 kann mittels spanender oder nichtspanender Verfahren in gängiger Weise hergestellt werden. Mit dem Hauptkörper 7 ist in der vorliegenden Bauform des Hohlkolbens 1 der Gelenkkopf 6 ausgebildet, welcher eine Bohrung 9 aufweist, durch welche das Hydraulikfluid zum Gleitschuh zum Zwecke der Schmierung und hydrostatischen Entlastung strömt.The exemplary embodiment illustrated in FIG. 1A shows the simplest variant of a hollow piston 1 according to the invention. The hollow piston 1 comprises a main body 7, which has a recess 8 extending over at least part of the axial length of the main body 7. The recess 8 can be produced in a conventional manner by means of cutting or non-cutting methods. With the main body 7 in the present design of the hollow piston 1, the condyle 6 is formed, which has a bore 9 through which flows the hydraulic fluid to the shoe for the purpose of lubrication and hydrostatic discharge.

Die Hohlkugeln 4 der Hohlkugelfüllung 2 werden nun in die Ausnehmung 8 des Hohlkolbens 1 eingefüllt und nach angemessener Verdichtung mittels Sintern, Löten oder Kleben miteinander sowie mit dem Hohlkolben 1 verbunden. Das den Hohlkolben 1 durchfließende Hydraulikfluid findet zwischen den einzelnen Hohlkugeln 4 genügend Raum, um zum Gleitschuh zu strömen. Das Totvolumen des Hohlkolbens 1 ist dabei die Summe aller zwischen den Hohlkugeln 4 verbleibenden Hohlräume 3.The hollow balls 4 of the hollow sphere filling 2 are now filled into the recess 8 of the hollow piston 1 and, after appropriate compression by means of sintering, soldering or gluing together and connected to the hollow piston 1. The hydraulic fluid flowing through the hollow piston 1 has enough space between the individual hollow spheres 4 to form the sliding shoe to stream. The dead volume of the hollow piston 1 is the sum of all remaining between the hollow balls 4 cavities third

Der Vorteil des in Fig. 1A dargestellten Ausführungsbeispiels ist insbesondere die einfache und damit kostengünstige Herstellbarkeit.The advantage of the embodiment shown in Fig. 1A is in particular the simple and thus cost manufacturability.

In Fig. 1B ist ein zweites Ausführungsbeispiel eines Hohlkolbens 1 in konventioneller Bauweise dargestellt. Um das Totvolumen weiter zu reduzieren, wird in diesem Ausführungsbeispiel nach Befüllen des Hohlkolbens 1 mit Hohlkugeln 4 ein Deckel 5 eingesetzt, welcher den Hohlkolben 1 abschließt. In dem Deckel 5 ist eine Bohrung 10 ausgebildet, welche dem Hydraulikfluid das Zuströmen in die Ausnehmung 8 des Hohlkolbens 1 ermöglicht. Um sowohl die Verbindung des Deckels 5 mit dem Hohlkolben 1 als auch die Verbindung der Hohlkugeln 4 der Hohlkugelfüllung 2 untereinander sowie mit dem Hohlkolben 1 und dem Deckel 5 zu erreichen, wird der Hohlkolben 1 gesintert. Dadurch ergibt sich ein Hohlkolben 1 mit einem sehr geringen Totvolumen, einer hohen Stabilität und einer gegenüber einem Massivkolben deutlich reduzierten Masse. Das Hydraulikfluid fließt wie im vorigen Ausführungsbeispiel durch die noch vorhandenen Hohlräume 3 zwischen den Hohlkugeln 4.In Fig. 1B, a second embodiment of a hollow piston 1 is shown in a conventional construction. In order to further reduce the dead volume, a cover 5 is used in this embodiment after filling the hollow piston 1 with hollow balls 4, which closes the hollow piston 1. In the cover 5, a bore 10 is formed, which allows the hydraulic fluid to flow into the recess 8 of the hollow piston 1. In order to achieve both the connection of the cover 5 with the hollow piston 1 and the connection of the hollow balls 4 of the hollow ball filling 2 with each other and with the hollow piston 1 and the cover 5, the hollow piston 1 is sintered. This results in a hollow piston 1 with a very low dead volume, high stability and compared to a solid piston significantly reduced mass. The hydraulic fluid flows as in the previous embodiment through the remaining cavities 3 between the hollow balls 4th

Fig. 1C zeigt ein weiteres Ausführungsbeispiel eines erfindungsgemäß ausgestalteten Hohlkolbens 1. Da es in manchen Situationen möglich sein kann, daß beispielsweise bedingt durch die zu geringe Größe der Hohlräume 3 zwischen den Hohlkugeln 4 das Hydraulikfluid nicht mehr genügend ungedrosselt durch den Hohlkolben 1 strömen kann, kann eine zentrale Durchgangsbohrung 11 in einem in den Hohlkolben i eingesetzten Rohr 12 vorgesehen sein. Die Befüllung des Hohlkolbens 1 mit Hohlkugeln 4 erfolgt dann dementsprechend um das Rohr 8 herum. Ebenso wie im vorigen Ausführungsbeispiel wird nach der Befüllung und der Montage des Rohrs 12 und des Deckels 5 der Hohlkolben 1 gesintert, um die Verbindung zwischen den einzelnen Bauteilen untereinander, den Hohlkugeln 4 untereinander sowie zwischen den Hohlkugeln 4 und den genannten Bauteilen zu erzielen. Das Rohr 12 kann dabei wahlweise den Deckel 5 durch eine Ausnehmung 13 wie in Fig. 1C dargestellt durchgreifen oder der Deckel 5 und das Rohr 12 können einteilig unter Einbeziehung der Bohrung 10 ausgeführt sein.1C shows a further embodiment of a hollow piston 1 designed according to the invention. Since it may be possible in some situations that due to the too small size of the cavities 3 between the hollow spheres 4, the hydraulic fluid can no longer flow through the hollow piston 1 sufficiently unthrottled, For example, a central through-bore 11 may be provided in a tube 12 inserted in the hollow piston i. The filling of the hollow piston 1 with hollow balls 4 is then carried out accordingly around the tube 8 around. As in the previous embodiment, after the filling and assembly of the tube 12 and the cover 5, the hollow piston 1 is sintered to the connection between the individual components with each other, the hollow balls 4 with each other and between the hollow balls 4 and to achieve the said components. The tube 12 can optionally pass through the lid 5 through a recess 13 as shown in Fig. 1C or the lid 5 and the tube 12 can be made in one piece with the inclusion of the bore 10.

Vorteilhaft ist bei diesem Ausführungsbeispiel insbesondere die effektive Reduzierung des Totvolumens und die hohe Stabilität des Hohlkolbens 1.In this exemplary embodiment, the effective reduction of the dead volume and the high stability of the hollow piston 1 are particularly advantageous.

Die Fig. 2A bis 2E zeigen Ausführungsbeispiele für die inverse Ausführung der Hohlkolben 1, bei welcher die als Kugelköpfe ausgebildete Gelenkköpfe 6 mit Gleitschuhen 14, welche sich an der Schrägscheibe der Axialkolbenmaschine abstützen, beispielsweise einstückig ausgebildet sind und in ein Lager 15 in dem Hauptkörper 7 des Hohlkolbens 1 schwenkbar eingreifen. Die Gelenkköpfe 6 weisen ebenfalls eine Bohrung 9 zur Fluidleitung auf.2A to 2E show embodiments for the inverse embodiment of the hollow piston 1, in which formed as ball joints rod ends 6 with sliding shoes 14 which are supported on the swash plate of the axial piston machine, for example, integrally formed and in a bearing 15 in the main body. 7 the hollow piston 1 pivotally engage. The rod ends 6 also have a bore 9 for fluid line.

In Fig. 2A ist eine einfache Ausführungsform gezeigt, welche den Vorteil der einfachen und kostengünstigen Herstellbarkeit hat. Die Hohlkugelfüllung 2 wird in die Ausnehmung 8 des Hohlkolbens 1 eingebracht. Dann wird der Hohlkolben 1 gesintert, um die erforderliche Verbindung zwischen den einzelnen Hohlkugeln 4 und dem Hohlkolben 1 herzustellen. Abschließend wird der Gelenkkopf 6 des Gleitschuhs 14 in das Lager 15 eingesetzt. Wie in den Ausführungsbeispielen, welche in den Fig. 1A und 1B dargestellt sind, umfließt das Hydraulikfluid die Hohlräume 3 zwischen den Hohlkugeln 4.In Fig. 2A, a simple embodiment is shown, which has the advantage of simple and inexpensive to manufacture. The hollow sphere filling 2 is introduced into the recess 8 of the hollow piston 1. Then, the hollow piston 1 is sintered to produce the required connection between the individual hollow balls 4 and the hollow piston 1. Finally, the condyle 6 of the shoe 14 is inserted into the bearing 15. As in the exemplary embodiments illustrated in FIGS. 1A and 1B, the hydraulic fluid flows around the cavities 3 between the hollow spheres 4.

Um das Totvolumen zu reduzieren bzw. zur Vermeidung möglicher Rückstände in den Hohlräumen 3 bei der Wärmebehandlung, kann auch, wie in Fig. 2B dargestellt, zwischen der Hohlkugelfüllung 2 und dem Gelenkkopf 6 ein Deckel 16 eingesintert sein, welcher ebenfalls eine Bohrung 17 zur Fluidleitung aufweist.In order to reduce the dead volume or to avoid possible residues in the cavities 3 in the heat treatment, and as shown in Fig. 2B, between the hollow ball filling 2 and the condyle 6, a lid 16 may be sintered, which also has a bore 17 for fluid line having.

Eine ähnlich einfache Ausführungsform wie in Fig. 2 A ist in Fig. 2C dargestellt, wo das Lager 15 gegen den Hohlkolben 1 abgeschlossen ist. Diese Form des Hohlkolbens 1 muß zur Fluidleitung in die Ausnehmung 8 des Hohlkolbens 1 ebenfalls mit einer Bohrung 17 versehen sein. Das Befüllen des Hohlkolbens 1 ist dadurch von der gegenüberliegenden Seite mit anschließendem Sintern wie bei Fig. 1A möglich.A similar simple embodiment as in Fig. 2 A is shown in Fig. 2C, where the bearing 15 is closed against the hollow piston 1. This shape of the hollow piston 1 must also be provided with a bore 17 for fluid conduction into the recess 8 of the hollow piston 1. The filling of the hollow piston 1 is thereby possible from the opposite side with subsequent sintering as in Fig. 1A.

Fig. 2D weist analog zu Fig. 1B einen Deckel 5 mit einer Bohrung 10 auf, welcher zur Reduzierung des Totvolumens nach der Befüllung des Hohlkolbens 1 mit Hohlkugeln 4 in den Hohlkolben 1 eingesetzt und anschließend durch Sintern mit dem Hohlkolben 1 und den Hohlkugeln 4 verbunden wird.FIG. 2D has, analogously to FIG. 1B, a cover 5 with a bore 10, which is used to reduce the dead volume after filling the hollow piston 1 with hollow balls 4 in the hollow piston 1 and then connected by sintering to the hollow piston 1 and the hollow balls 4 becomes.

Ebenso ist in den in Fig. 2E dargestellten Hohlkolben 1 in Analogie zu Fig. 1C ein Rohr 12 mit einer Durchgangsbohrung 11 angeordnet, durch welche das Hydraulikfluid zum Gleitschuh zum Zweck der Schmierung und hydrostatischen Entlastung strömt. Die Hohlkugeln 4 sind wiederum kleiner und so eingefüllt, daß sie nach dem Sintern mit dem Rohr 12, dem Deckel 5 und dem Hohlkolben 1 sowie untereinander einen Verbund bilden.Likewise, in the hollow piston 1 shown in FIG. 2E, by analogy with FIG. 1C, a tube 12 is arranged with a through-bore 11 through which the hydraulic fluid flows to the sliding shoe for the purpose of lubrication and hydrostatic discharge. The hollow balls 4 are again smaller and filled so that they form after sintering with the tube 12, the lid 5 and the hollow piston 1 and one another with each other.

Die Fig. 3A bis 3C zeigen weitere Ausführungsbeispiele von erfindungsgemäß ausgestalteten Hohlkolben 1 in inverser Bauweise. Die Ausführungsbeispiele sind in Analogie zu den in den Fig. 2C bis 2E dargestellten Ausführungsbeispielen zu sehen, wobei in den im folgenden beschriebenen Ausführungsbeispielen die Wandung des Hauptkörpers 7 aus einem Rohrstück geformt ist und eine in den Fig. 2C bis 2E einteilig mit dem Hauptkörper 7 des Hohlkolbens 1 ausgebildete Lagerhülse 18 als separates Bauteil ausgebildet ist. Die Lagerhülse 18 weist ebenfalls eine Bohrung 17 auf. Die Verbindung zwischen dem Hauptkörper 7 und der Lagerhülse 18 kann wie bei den anderen Bauteilen mittels Sintern hergestellt werden.FIGS. 3A to 3C show further exemplary embodiments of hollow piston 1 configured in accordance with the invention in an inverse design. The embodiments are to be seen in analogy to the embodiments shown in FIGS. 2C to 2E, wherein in the embodiments described below, the wall of the main body 7 is formed from a piece of pipe and one in Figs. 2C to 2E integral with the main body formed of the hollow piston 1 bearing sleeve 18 is formed as a separate component. The bearing sleeve 18 also has a bore 17. The connection between the main body 7 and the bearing sleeve 18 can be made by sintering as in the other components.

Vorteil der separaten Lagerhülse ist insbesondere die einfachere Herstellbarkeit des Hauptkörpers 7 aus einem Rohrstück, welche besonders kostengünstig ist.Advantage of the separate bearing sleeve is in particular the ease of manufacture of the main body 7 of a piece of pipe, which is particularly inexpensive.

Claims (27)

  1. Hollow piston (1) for a piston machine, comprising a main body (7) in which a recess (8) is formed over at least a part of the axial length of the main body (7), characterised in that the recess (8) is filled at least partially with a filling (2) of hollow spheres which forms a bond with the main body (7) by means of sintering.
  2. Hollow piston according to claim 1, characterised in that the filling (2) of hollow spheres consists of individual pourable hollow spheres (4).
  3. Hollow piston according to claim 2, characterised in that cavities (3) remain between the hollow spheres (4) after sintering.
  4. Hollow piston according to claim 3, characterised in that a hydraulic fluid flowing through the hollow piston (1) flows through the cavities (3).
  5. Hollow piston according to any one of claims 1 to 4, characterised in that the hollow piston (1) includes a joint head (6) in the form of a ball which is connectable to a guide shoe.
  6. Hollow piston according to claim 5, characterised in that the hollow piston (1) is open on a side opposite the joint head (6) after filling.
  7. Hollow piston according to claim 5, characterised in that the hollow piston (1) is closed by a cover (5) on a side opposite the joint head (6) after filling.
  8. Hollow piston according to claim 7, characterised in that the cover (5) is joined to the hollow piston (1) by means of sintering.
  9. Hollow piston according to claim 7 or 8, characterised in that the cover (5) includes a bore (10).
  10. Hollow piston according to any one of claims 1 to 4, characterised in that the hollow piston includes a bearing socket (15) formed in one piece with the hollow piston, in which bearing socket (15) a joint head (6) formed in one piece with a guide shoe (14) is insertable.
  11. Hollow piston according to claim 10, characterised in that an end of the hollow piston (1) facing towards the joint head (6) is open and an end of the hollow piston (1) facing away from the joint head is sealed.
  12. Hollow piston according to claim 10, characterised in that a cover (16) is formed between the filling (2) of spheres and the joint head (6).
  13. Hollow piston according to claim 11, characterised in that the cover (16) includes a bore (17).
  14. Hollow piston according to claim 10, characterised in that an end of the hollow piston (1) facing towards the joint head (6) is sealed by means of a bearing shell (18) formed in one piece with the hollow piston and an end of the hollow piston (1) facing away from the joint head is open.
  15. Hollow piston according to claim 14, characterised in that the hollow piston (1) is sealed on a side opposite the joint head (6) by a cover (5) after filling.
  16. Hollow piston according to claim 15, characterised in that the cover (5) is joined to the hollow piston (1) by means of sintering.
  17. Hollow piston according to claim 15 or 16, characterised in that the cover (5) includes a bore (10).
  18. Hollow piston according to any one of claims 1 to 17, characterised in that a tube (12) which extends over the axial length of the recess (8) is arranged in the recess (8).
  19. Hollow piston according to claim 18, characterised in that a through-bore (11) is formed in the tube (12).
  20. Hollow piston according to claim 18 or 19, characterised in that the filling (2) of spheres surrounds the tube (12).
  21. Hollow piston according to any one of claims 1 to 20, characterised in that the wall of the hollow piston (1) is produced in one piece from a section of tube.
  22. Hollow piston according to claim 21, characterised in that a bearing shell (18) is formed as a separate component.
  23. Hollow piston according to claim 22, characterised in that a bearing shell (18) is inserted in the hollow piston and joined thereto by means of sintering.
  24. Method for producing a hollow piston (1) for a piston machine, comprising the following process steps:
    - production of a main body (7) of the hollow piston (1) in which a recess (8) is formed over at least a part of the axial length of the hollow piston (1);
    - filling of the recess (8) at least partially with a filling (2) of hollow spheres (4), and
    - sintering of the hollow piston (1) with the filling (2) of hollow spheres to produce a bond between the main body (7) and the filling (2) of hollow spheres.
  25. Method according to claim 24, characterised in that the recess (8) is filled with individual pourable hollow spheres.
  26. Method according to claim 24, characterised in that the filling of hollow spheres is preformed outside the recess (8) by sintering and is then inserted in the recess (8).
  27. Method according to any one of claims 24 to 26, characterised in that an additional process step, in which the hollow piston (1) is provided with a cover (5), is provided prior to sintering.
EP20030001458 2002-02-18 2003-01-22 Pump piston filled with hollow spheres Expired - Fee Related EP1336756B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10206729 2002-02-18
DE2002106729 DE10206729B4 (en) 2002-02-18 2002-02-18 Hollow piston with hollow ball filling

Publications (3)

Publication Number Publication Date
EP1336756A2 EP1336756A2 (en) 2003-08-20
EP1336756A3 EP1336756A3 (en) 2003-12-03
EP1336756B1 true EP1336756B1 (en) 2006-10-18

Family

ID=27618752

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20030001458 Expired - Fee Related EP1336756B1 (en) 2002-02-18 2003-01-22 Pump piston filled with hollow spheres

Country Status (2)

Country Link
EP (1) EP1336756B1 (en)
DE (2) DE10206729B4 (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102009056903A1 (en) 2009-12-03 2011-06-09 Danfoss A/S Hydraulic piston machine, in particular water-hydraulic machine
DE102013211893A1 (en) * 2013-06-24 2014-12-24 Robert Bosch Gmbh Hollow piston for a swashplate machine and swashplate machine
DE102016212231A1 (en) * 2016-07-05 2018-01-11 Mahle International Gmbh Piston for an axial piston machine

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63266269A (en) * 1987-04-21 1988-11-02 Taiho Kogyo Co Ltd Piston for hydraulic device
DE3902032A1 (en) * 1989-01-25 1990-07-26 Mtu Muenchen Gmbh SINED LIGHTWEIGHT MATERIAL WITH MANUFACTURING PROCESS
DE3919329C1 (en) * 1989-06-13 1990-12-06 Hydromatik Gmbh, 7915 Elchingen, De
US4925740A (en) * 1989-07-28 1990-05-15 Rohr Industries, Inc. Hollow metal sphere filled stabilized skin structures and method of making
DE4108786C2 (en) * 1991-03-18 1995-01-05 Hydromatik Gmbh Light pistons for hydrostatic axial and radial piston machines
DE4338457C2 (en) * 1993-11-11 1998-09-03 Mtu Muenchen Gmbh Component made of metal or ceramic with a dense outer shell and porous core and manufacturing process
US5642654A (en) * 1994-09-01 1997-07-01 Sundstrand Corporation Piston and method of manufacturing the same
DE19929760C2 (en) * 1999-06-29 2003-05-22 Fraunhofer Ges Forschung Process for the production of metallic, oxide or ceramic hollow spheres
US6431051B1 (en) * 2000-03-31 2002-08-13 Sauer-Danfoss Inc. Closed cavity hydraulic piston and method of making the same
US6338293B1 (en) * 2000-06-30 2002-01-15 Sauer-Danfoss Inc. Reduced oil volume piston assembly for a hydrostatic unit

Also Published As

Publication number Publication date
DE50305393D1 (en) 2006-11-30
EP1336756A2 (en) 2003-08-20
DE10206729A1 (en) 2003-09-18
EP1336756A3 (en) 2003-12-03
DE10206729B4 (en) 2004-02-05

Similar Documents

Publication Publication Date Title
DE102013021065A1 (en) Piston machine with support piston
DE2320554A1 (en) PISTONS FOR HYDRAULIC MACHINERY
DE102006034736B4 (en) Bearing shell and bearing for connecting rod
EP0315137B1 (en) Method of manufacturing crankshafts
WO2015173390A1 (en) Piston machine having a connecting-rod shank having a plurality of parts and connecting rod having such a connecting-rod shank
EP1205652B1 (en) Variable compression ratio mechanism with two hydraulically operated valves in the crank shaft
EP2784313A1 (en) Piston for an axial piston machine
EP1336756B1 (en) Pump piston filled with hollow spheres
DE19706075C2 (en) Piston for a hydrostatic machine
DE10109596C2 (en) Piston for a hydrostatic cylinder block
DE2812416C2 (en) Cylinder drum for an axial piston machine
DE10040823A1 (en) Fabrication method for filled hydraulic piston for hydraulic pump or motor with aluminum insert fitted into central piston blank bore and retained by cold-formed piston material
DE19913889B4 (en) reciprocating engine
EP1336449B2 (en) Hollow piston and method for manucturing it by diffusion welding or sintering
DE102009020110A1 (en) Hydrostatic displacement machine e.g. multi-stroke axial piston engine, has rolling body supported in openings of piston by slide bearing element, where element is produced by sintering process in openings of piston
DE4129892C2 (en) Axial piston machine with pistons with sliding rings
DE102009021067B4 (en) Thin-walled insert for a cylinder of a piston engine and a cylinder liner, cylinder and engine block of a piston engine, and method for their production
EP0900610B1 (en) Process for preparing a bearing of sintered metal for ceramic shafts and bearing produced thereby
DE102018132718A1 (en) Crank drive for a reciprocating machine
WO2020113250A1 (en) Length-adjustable connecting rod having a press-fit connection
EP3071827B1 (en) Roller for a roller plunger of a high pressure fuel pump, roller plunger, high pressure fuel pump, and internal combustion engine
EP3418533B1 (en) Connecting rod for a combustion engine with variable compression
AT522161B1 (en) Kit for making VCR connecting rods
EP0326606A1 (en) Composite crankshaft and process for manufacturing it
WO2019038033A1 (en) Method for producing an internal combustion engine

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT SE SI SK TR

AX Request for extension of the european patent

Extension state: AL LT LV MK RO

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT SE SI SK TR

AX Request for extension of the european patent

Extension state: AL LT LV MK RO

17P Request for examination filed

Effective date: 20040226

AKX Designation fees paid

Designated state(s): DE FR GB IT SE

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB IT SE

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)

Effective date: 20061018

REF Corresponds to:

Ref document number: 50305393

Country of ref document: DE

Date of ref document: 20061130

Kind code of ref document: P

REG Reference to a national code

Ref country code: SE

Ref legal event code: TRGR

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20070719

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20090123

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20090123

Year of fee payment: 7

Ref country code: SE

Payment date: 20090126

Year of fee payment: 7

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20090120

Year of fee payment: 7

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20100122

EUG Se: european patent has lapsed
REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20100930

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100201

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100122

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100122

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20100123

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20130326

Year of fee payment: 11

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 50305393

Country of ref document: DE

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 50305393

Country of ref document: DE

Effective date: 20140801

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20140801