EP0888499B1 - Piston for a hydrostatic axial-piston machine - Google Patents

Piston for a hydrostatic axial-piston machine Download PDF

Info

Publication number
EP0888499B1
EP0888499B1 EP97905034A EP97905034A EP0888499B1 EP 0888499 B1 EP0888499 B1 EP 0888499B1 EP 97905034 A EP97905034 A EP 97905034A EP 97905034 A EP97905034 A EP 97905034A EP 0888499 B1 EP0888499 B1 EP 0888499B1
Authority
EP
European Patent Office
Prior art keywords
piston
curvature
bevel
skirt surface
radius
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 - Lifetime
Application number
EP97905034A
Other languages
German (de)
French (fr)
Other versions
EP0888499A1 (en
Inventor
Josef Beck
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 EP0888499A1 publication Critical patent/EP0888499A1/en
Application granted granted Critical
Publication of EP0888499B1 publication Critical patent/EP0888499B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05C—INDEXING SCHEME RELATING TO MATERIALS, MATERIAL PROPERTIES OR MATERIAL CHARACTERISTICS FOR MACHINES, ENGINES OR PUMPS OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES
    • F05C2201/00—Metals
    • F05C2201/04—Heavy metals
    • F05C2201/0469—Other heavy metals
    • F05C2201/0475—Copper or alloys thereof
    • F05C2201/0478—Bronze (Cu/Sn alloy)

Definitions

  • the invention relates to a piston for a hydrostatic axial piston machine, arranged in particular in a swashplate design with a cylinder drum axial cylinder bores and a swash plate on which the pistons are supported.
  • the Pistons consist of a piston skirt with a piston face and with an in the cylindrical bore reciprocating cylindrical surface and one piston head supporting the swash plate.
  • Such pistons for axial piston machines are known for example from DE A 23 20 554 and DE-A 36 09 892. At least the end regions of the cylindrical outer surface facing the end pressure surface of these pistons are chamfered or rounded off for a variety of reasons. It is known to the person skilled in the art that in such machines the piston play and the kinematics of such machines inevitably lead to an alternating inclination of the piston in the cylinder bore, which causes increased friction and wear, particularly in the case of soft cylinder material, for example bronze. During the piston movement, a scraping effect occurs on the wall of the cylinder bore through the end edges of the piston / outer surface.
  • the invention has for its object a piston for a hydrostatic To create an axial piston machine in which the wear at the insertion and removal point the piston skirt is further reduced and at the same time the hydraulic-mechanical and volumetric efficiency of the hydrostatic machine is improved.
  • the piston is according to the preamble of claim 1 characterized in that the outer surface of the piston skirt on its in the Piston front end merging front end area and / or their towards the piston head a rear bevel with a constantly changing radius of curvature having.
  • This is not only a reduction in the friction at the piston ends thereby achieved that the chamfer profile the different sized inclinations of the Piston is adapted in its back and forth movement in the cylinder bore, but a lower tolerance for the permissible piston play can also be assumed become.
  • the invention enables a better lubricating film build-up for removing the Frictional heat of the cylinder bore wall. After all, it's a surprising one Improvement of hydraulic-mechanical and volumetric efficiency, were measured up to 3%, achieved in that the chamfer profile the effective face pressure area of the piston enlarged.
  • the axial piston machine shown schematically in section in FIG Swashplate design consists of a housing 1, the input / output shaft 2, the Cylinder drum 3, the housing cover 4 with control disc 5, the swash plate 6, the Pistons 7, which move in cylinder bores 8 of the cylinder drum 3 in that they are supported by sliding shoes 9 on the swash plate 6.
  • the inclination of the Swash plate 6 can by an adjusting device 10 and thus the stroke volume of the Machine can be changed.
  • this axial piston machine is of the usual type and there is no need for a more detailed description.
  • the pistons 7, in the embodiment shown hollow pistons, consist of a Piston shaft 15 with a pressure-sensitive piston face 11.
  • the piston shaft 15 has one cylindrical outer surface 12 which slides on the wall 13 of the cylinder bore 8.
  • On the side facing away from the piston face 11 goes into the piston head 14 over, which is mounted in the shoe 9.
  • To illustrate the kinematics in the Figure 2 shows the inclination of the pistons 7 in the cylinder bores 8 greatly exaggerated shown.
  • the decisive points for the emergence of the scraping effect are the end areas of the Piston skirt.
  • the front end portion of the piston skirt 15, in which the Piston shaft 15 merges into the piston end face 11 is designated Y and for Embodiments in Figures 4 and 6 shown enlarged.
  • the rear end area of the piston skirt 15 is designated X and for the two embodiments in the Figures 5 and 7 are shown enlarged.
  • the chamfer profile 16 begins at the piston face 11 with a small one Radius of curvature R1 and continues with increasing radii of curvature to the lateral surface 12, in which the radius of curvature R2 reaches infinite size.
  • the chamfer profile 16 tapers into the lateral surface, becoming ever flatter.
  • the between the piston face 11 and the beginning of the chamfer profile 16 with a small Radius of curvature R1 resulting edge 17 is functionally meaningless since this edge in no inclined position of the piston in the area of the wall of the cylinder bore comes. Generally, this edge 17 is so far inward of the piston center axis laid, i.e.
  • the chamfer profile 16 is so large that it is also used as an introductory phase Assembly of the pistons to avoid damage to the cylinder bore wall serves.
  • the chamfer profile 18 in the rear end region of the piston skirt 15 according to FIG. 5 starts from the side of the piston head 14 with a small radius of curvature R3, runs with continuously increasing radii of curvature into the outer surface 12 of the piston, where it reaches the radius of curvature R2 of infinite size of the lateral surface.
  • the chamfer profile 19 has on the side of the Piston face 11 initially again has a small radius R4, which remains constant or increasing continuously changes into a large radius of curvature R5.
  • This Radius of curvature R5 can also be infinitely large, which means that in this area a conical annular chamfer pressure surface 20 is formed.
  • Radius of curvature R6 continues, the radii of curvature R7 etc. again increasing continuously until they have the radius of curvature R2 with the value infinite of the lateral surface 12 reach the piston, so that the chamfer profile 19 here also continuously and flat in the lateral surface 12 merges.
  • the conical annular pressure surface 20 increases the hydraulic-volumetric efficiency of the piston.
  • the angle between one axial surface line of the pressure surface 20 and an axial surface line of the surface surface 12 of the piston should be less than 5 °.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Pistons, Piston Rings, And Cylinders (AREA)

Description

Die Erfindung betrifft einen Kolben für eine hydrostatische Axialkolbenmaschine, insbesondere in Schrägscheibenbauform mit einer Zylindertrommel, darin angeordneten axialen Zylinderbohrungen und einer Schrägscheibe, an der die Kolbenabgestützt sind. Die Kolben bestehen aus einem Kolbenschaft mit einer Kolbenstirnfläche und mit einer sich in der Zylinderbohrung hin- und herbewegenden zylindrischen Mantelfläche sowie einem sich an der Schrägscheibe abstützenden Kolbenkopf.The invention relates to a piston for a hydrostatic axial piston machine, arranged in particular in a swashplate design with a cylinder drum axial cylinder bores and a swash plate on which the pistons are supported. The Pistons consist of a piston skirt with a piston face and with an in the cylindrical bore reciprocating cylindrical surface and one piston head supporting the swash plate.

Derartige Kolben für Axialkolbenmaschinen sind beispielsweise aus der DE A 23 20 554 und DE-A 36 09 892 bekannt. Zumindest die der stirnseitigen Druckfläche dieser Kolben zugewandten Endbereiche der zylindrischen Mantelfläche sind aus den verschiedensten Gründen abgeschrägt oder abgerundet. Dem Fachmann ist bekannt, daß bei derartigen Maschinen das Kolbenspiel und die Kinematik solcher Maschinen zwangsläufig zu einer wechselnden Schrägstellung des Kolbens in der Zylinderbohrung führt, was eine erhöhte Reibung und Verschleiß bewirkt, insbesondere bei weichem Zylindermaterial, z.B. Bronze. Während der Kolbenbewegung tritt an der Wandung der Zylinderbohrung ein Schabeeffekt durch die Endkanten der Kolben/Mantelfläche auf. Damit während der Kolbenbewegung an der Wandung der Zylinderbohrung kein Schabeeffekt auftritt, sind die Zylinderbohrungen in diesem Bereich teilweise frei bearbeitet. Um die Abnützung der Wandungen des Zylinders zu verringern, ist bei dem Kolben nach DE-A 23 20 554 der innere Endabschnitt des Kolbens zur stirnseitigen Druckfläche hin abgeschrägt. Bei dieser Ausführung mit Anfasungen (Abschrägungen) tritt ohne eine freie Bearbeitung der Wandung der Zylinderbohrung weiterhin Verschleiß an der Ein- und Austauchstelle des Kolbenschaftes auf, da die Anfasung ihrerseits Kanten hat.
Es wurde festgestellt, daß diese Kanten der Anfasung oder auch mit gleichem, kleinem Krümmungsradius gebrochene Kanten die genannte Schabwirkung nicht vermeiden. Diese Schabwirkung verhindert den Aufbau des zur Abführung der Reibungswärme benötigten Leckölschmierfilmes und neigt zum Verklemmen der Kolben in der Zylinderbohrung (Schubladeneffekt). Such pistons for axial piston machines are known for example from DE A 23 20 554 and DE-A 36 09 892. At least the end regions of the cylindrical outer surface facing the end pressure surface of these pistons are chamfered or rounded off for a variety of reasons. It is known to the person skilled in the art that in such machines the piston play and the kinematics of such machines inevitably lead to an alternating inclination of the piston in the cylinder bore, which causes increased friction and wear, particularly in the case of soft cylinder material, for example bronze. During the piston movement, a scraping effect occurs on the wall of the cylinder bore through the end edges of the piston / outer surface. So that there is no scraping effect on the wall of the cylinder bore during the piston movement, the cylinder bores in this area are partially freely machined. In order to reduce the wear on the walls of the cylinder, in the piston according to DE-A 23 20 554 the inner end portion of the piston is chamfered towards the end pressure surface. In this version with chamfers (bevels), wear continues to occur at the insertion and removal point of the piston skirt without free machining of the wall of the cylinder bore, since the chamfer itself has edges.
It was found that these edges of the chamfer or edges broken with the same small radius of curvature do not avoid the above-mentioned scraping effect. This scraping effect prevents the build-up of the oil leakage film required to dissipate the frictional heat and tends to jam the pistons in the cylinder bore (drawer effect).

Der Erfindung liegt die Aufgabe zugrunde, einen Kolben für eine hydrostatische Axialkolbenmaschine zu schaffen, bei dem der Verschleiß an der Ein- und Austauchstelle des Kolbenschaftes weiter vermindert ist und gleichzeitig der hydraulisch-mechanische und volumetrische Wirkungsgrad der hydrostatischen Maschine verbessert ist.The invention has for its object a piston for a hydrostatic To create an axial piston machine in which the wear at the insertion and removal point the piston skirt is further reduced and at the same time the hydraulic-mechanical and volumetric efficiency of the hydrostatic machine is improved.

Zur Lösung dieser Aufgabe ist der Kolben nach dem Oberbegriff des Anspruches 1 dadurch gekennzeichnet, daß die Mantelfläche des Kolbenschaftes an ihrem in die Kolbenstirnseite übergehenden vorderen Endbereich und/oder ihrem zum Kolbenkopf hin liegenden hinteren Endbereich eine Anfasung mit stetig veränderten Krümmungsradien aufweist. Dadurch ist nicht nur eine Reduzierung der Reibung an den Kolbenschaftenden dadurch erreicht, daß das Anfasungsprofil den unterschiedlich großen Schrägstellungen des Kolbens bei seiner Hin- und Herbewegung in der Zylinderbohrung angepaßt ist, sondern es kann auch von einer geringeren Toleranz für das zulässige Kolbenspiel ausgegangen werden. Die Erfindung ermöglicht einen besseren Schmierfilmaufbau zur Abführung der Reibwärme der Zylinderbohrungswandung. Schließlich ist eine überraschende Verbesserung des hydraulisch-mechanischen und volumetrischen Wirkungsgrades, gemessen wurden bis zu 3 %, dadurch erreicht, daß das Anfasungsprofil die wirksame stirnseitige Druckfläche des Kolbens vergrößert.To achieve this object, the piston is according to the preamble of claim 1 characterized in that the outer surface of the piston skirt on its in the Piston front end merging front end area and / or their towards the piston head a rear bevel with a constantly changing radius of curvature having. This is not only a reduction in the friction at the piston ends thereby achieved that the chamfer profile the different sized inclinations of the Piston is adapted in its back and forth movement in the cylinder bore, but a lower tolerance for the permissible piston play can also be assumed become. The invention enables a better lubricating film build-up for removing the Frictional heat of the cylinder bore wall. After all, it's a surprising one Improvement of hydraulic-mechanical and volumetric efficiency, were measured up to 3%, achieved in that the chamfer profile the effective face pressure area of the piston enlarged.

Zweckmäßige Ausführungsformen sind in den Unteransprüchen gekennzeichnet.Appropriate embodiments are characterized in the subclaims.

Beispielsweise Ausführungsformen der Erfindung werden im Folgenden anhand der Zeichnungen näher beschrieben. Es zeigen:

  • Fig. 1 schematisch im Schnitt eine Axialkolbenmaschine in Schiefscheibenbauart,
  • Fig. 2 schematisch in einer Schnittansicht Zylindertrommel, Schiefscheibe und Kolben mit stark übertrieben dargestellter Schrägstellung der Kolben in den Zylinderbohrungen,
  • Fig. 3 im Schnitt einen Kolben mit Gleitschuh,
  • Fig. 4 vergrößert im Ausschnitt den Bereich Y in Figur 3,
  • Fig. 5 vergrößert im Ausschnitt den Bereich X in Figur 3,
  • Fig. 6 vergrößert im Ausschnitt den Bereich Y in Figur 3 einer anderen Ausführungsform und
  • Fig. 7 vergrößert im Ausschnitt den Bereich X in Figur 3 der anderen Ausführungsform.
    • For example, embodiments of the invention are described in more detail below with reference to the drawings. Show it:
  • 1 schematically shows an axial piston machine in swash plate design,
  • 2 shows a schematic sectional view of the cylinder drum, swash plate and piston with the pistons in the cylinder bores shown in a greatly exaggerated manner,
  • 3 in section a piston with a sliding shoe,
  • 4 enlarges the area Y in FIG. 3,
  • 5 enlarges the area X in FIG. 3,
  • FIG. 6 enlarges the area Y in FIG. 3 of another embodiment and
  • FIG. 7 enlarges the area X in FIG. 3 of the other embodiment.

    • Die in Figur 1 schematisch im Schnitt dargestellte Axialkolbenmaschine in Schrägscheibenbauform besteht aus einem Gehäuse 1, der An/Abtriebswelle 2, der Zylindertrommel 3, dem Gehäusedeckel 4 mit Steuerscheibe 5, der Schiefscheibe 6, den Kolben 7, die sich in Zylinderbohrungen 8 der Zylindertrommel 3 dadurch bewegen, daß sie sich über Gleitschuhe 9 an der Schiefscheibe 6 abstützen. Die Schrägstellung der Schiefscheibe 6 kann durch eine Verstelleinrichtung 10 und damit das Hubvolumen der Maschine verändert werden. Insgesamt ist diese Axialkolbenmaschine von üblicher Bauart und es erübrigt sich eine nähere Beschreibung.The axial piston machine shown schematically in section in FIG Swashplate design consists of a housing 1, the input / output shaft 2, the Cylinder drum 3, the housing cover 4 with control disc 5, the swash plate 6, the Pistons 7, which move in cylinder bores 8 of the cylinder drum 3 in that they are supported by sliding shoes 9 on the swash plate 6. The inclination of the Swash plate 6 can by an adjusting device 10 and thus the stroke volume of the Machine can be changed. Overall, this axial piston machine is of the usual type and there is no need for a more detailed description.

    Die Kolben 7, bei der gezeigten Ausführungsform Hohlkolben, bestehen aus einem Kolbenschaft 15 mit druckwirksarner Kolbenstirnseite 11. Der Kolbenschaft 15 hat eine zylindrische Mantelfläche 12, welche an der Wand 13 der Zylinderbohrung 8 gleitet. Auf der der Kolbenstirnseite 11 abgewandten Seite geht der Kolbenschaft in den Kolbenkopf 14 über, der in dem Gleitschuh 9 gelagert ist. Zur Verdeutlichung der Kinematik ist in der Figur 2 die Schrägstellung der Kolben 7 in den Zylinderbohrungen 8 stark übertrieben dargestellt.The pistons 7, in the embodiment shown hollow pistons, consist of a Piston shaft 15 with a pressure-sensitive piston face 11. The piston shaft 15 has one cylindrical outer surface 12 which slides on the wall 13 of the cylinder bore 8. On the side facing away from the piston face 11 goes into the piston head 14 over, which is mounted in the shoe 9. To illustrate the kinematics in the Figure 2 shows the inclination of the pistons 7 in the cylinder bores 8 greatly exaggerated shown.

    Die für die Entstehung des Schabeffektes entscheidenden Stellen sind die Endbereiche des Kolbenschaftes. Der vordere Endbereich des Kolbenschaftes 15, in welchem der Kolbenschaft 15 in die Kolbenstirnseite 11 übergeht, ist mit Y bezeichnet und für die Ausführungsformen in den Figuren 4 und 6 vergrößert dargestellt. Der hintere Endbereich des Kolbenschaftes 15 ist mit X bezeichnet und für die beiden Ausführungsformen in den Figuren 5 und 7 vergrößert dargestellt.The decisive points for the emergence of the scraping effect are the end areas of the Piston skirt. The front end portion of the piston skirt 15, in which the Piston shaft 15 merges into the piston end face 11 is designated Y and for Embodiments in Figures 4 and 6 shown enlarged. The rear end area of the piston skirt 15 is designated X and for the two embodiments in the Figures 5 and 7 are shown enlarged.

    Das Anfasungsprofil 16 nach Figur 4 beginnt an der Kolbenstirnseite 11 mit einem kleinen Krümmungsradius R1 und setzt sich mit stetig größer werdenden Krümmungsradien bis zur Mantelfläche 12 fort, in welcher der Krümmungsradius R2 unendliche Größe erreicht. Das Anfasungsprofil 16 läuft stetig flacher werdend in die Mantelfläche aus. Die zwischen der Kolbenstirnseite 11 und dem Beginn des Anfasungsprofiles 16 mit kleinem Krümmungsradius R1 entstehende Kante 17 ist funktionell bedeutungslos, da diese Kante in keiner Schrägstellung des Kolbens in den Bereich der Wandung der Zylinderbohrung kommt. Im allgemeinen ist diese Kante 17 so weit nach innen zur Kolbenmittelachse gelegt, d.h. das Anfasungsprofil 16 ist so groß, daß es auch als Einführungsphase bei der Montage der Kolben zur Vermeidung von Beschädigungen der Zylinderbohrungswandung dient. Das Anfasungsprofil 18 im hinteren Endbereich des Kolbenschaftes 15 nach Figur 5 beginnt von der Seite des Kolbenkopfes 14 her mit kleinem Krümmungsradius R3, läuft mit stetig größer werdenden Krümmungsradien in die Mantelfläche 12 des Kolbens aus, wo sie den Krümmungsradius R2 unendlicher Größe der Mantelfläche erreicht.The chamfer profile 16 according to FIG. 4 begins at the piston face 11 with a small one Radius of curvature R1 and continues with increasing radii of curvature to the lateral surface 12, in which the radius of curvature R2 reaches infinite size. The chamfer profile 16 tapers into the lateral surface, becoming ever flatter. The between the piston face 11 and the beginning of the chamfer profile 16 with a small Radius of curvature R1 resulting edge 17 is functionally meaningless since this edge in no inclined position of the piston in the area of the wall of the cylinder bore comes. Generally, this edge 17 is so far inward of the piston center axis laid, i.e. the chamfer profile 16 is so large that it is also used as an introductory phase Assembly of the pistons to avoid damage to the cylinder bore wall serves. The chamfer profile 18 in the rear end region of the piston skirt 15 according to FIG. 5 starts from the side of the piston head 14 with a small radius of curvature R3, runs with continuously increasing radii of curvature into the outer surface 12 of the piston, where it reaches the radius of curvature R2 of infinite size of the lateral surface.

    Bei der Ausführungsform nach Figur 6 weist das Anfasungsprofil 19 auf der Seite der Kolbenstirnfläche 11 zunächst wiederum einen kleinen Radius R4 auf, der gleichbleibend oder größer werdend stetig in einen großen Krümmungsradius R5 übergeht. Dieser Krümmungsradius R5 kann auch unendlich groß sein, was bedeutet, daß in diesem Bereich eine konisch ringförmige Anfasungs-Druckfläche 20 gebildet wird. Anschließend setzt sich das Anfasungsprofil 19 mit gegenüber dem Krümmungsradius R5 wieder kleinerem Krümmungsradius R6 fort, wobei die Krümmungsradien R7 usw. wieder stetig größer werden, bis sie den Krümmungsradius R2 mit dem Wert unendlich der Mantelfläche 12 des Kolbens erreichen, so daß das Anfasungsprofil 19 auch hier kontinuierlich und flach in die Mantelfläche 12 übergeht. Die konisch ringförmige Druckfläche 20 erhöht den hydraulisch-volumetrischen Wirkungsgrad des Kolbens. Der Winkel zwischen einer axialen Mantellinie der Druckfläche 20 und einer axialen Mantellinie der Mantelfläche 12 des Kolbens sollte kleiner als 5° sein. Das Anfasungsprofil 21 nach Figur 7 im hinteren Endbereich X beginnt bei dieser Ausführungsform von der Kolbenkopfseite her mit einem konstanten Krümmungsradius R8, hat einen sehr großen, über einen kleinen Bereich konstant bleibenden Krümmungsradius R9 und geht dann mit gegenüber R9 zunächst etwas kleinerem Krümmungsradius in die anschließend wieder größer werdenden Krümmungsradien R10 über, bis diese den Krümmungsradius R2 unendlicher Größe der Mantelfläche 12 erreichen.In the embodiment according to FIG. 6, the chamfer profile 19 has on the side of the Piston face 11 initially again has a small radius R4, which remains constant or increasing continuously changes into a large radius of curvature R5. This Radius of curvature R5 can also be infinitely large, which means that in this area a conical annular chamfer pressure surface 20 is formed. Then sits down the chamfer profile 19 with a smaller radius than the radius of curvature R5 Radius of curvature R6 continues, the radii of curvature R7 etc. again increasing continuously until they have the radius of curvature R2 with the value infinite of the lateral surface 12 reach the piston, so that the chamfer profile 19 here also continuously and flat in the lateral surface 12 merges. The conical annular pressure surface 20 increases the hydraulic-volumetric efficiency of the piston. The angle between one axial surface line of the pressure surface 20 and an axial surface line of the surface surface 12 of the piston should be less than 5 °. The chamfer profile 21 according to FIG. 7 in the rear In this embodiment, end region X begins with a from the piston head side constant radius of curvature R8, has a very large, over a small area constant radius of curvature R9 and then goes a little bit with R9 smaller radius of curvature in the subsequently increasing Radii of curvature over R10 until they reach the radius of curvature R2 of infinite size Reach lateral surface 12.

    Claims (6)

    1. Piston for a hydrostatic axial piston machine, in particular of swash plate construction having a cylinder drum (3), axial cylinder bores (8) arranged therein and a swash plate (6) at which the pistons (7), movable back and forth in the cylinder bores, are supported, comprising a piston shaft (15) having a piston end face and having an adjoining cylindrical skirt surface (12) in the cylinder bore, and a piston head (14) supported on the swash plate (6),
      characterised in that,
      the skirt surface (12) of the piston shaft (15) has a bevel (16; 18; 19; 21) with continuously varied radiuses of curvature at its forward end region (Y) which transforms into the piston end face (11) and/or at its rear end region (X) lying towards the piston head.
    2. Piston according to claim 1,
      characterised in that,
      the bevel (16; 18; 19; 21) of the skirt surface, beginning from the piston shaft end with a small radius of curvature and then radiuses of curvature becoming larger, runs out with infinite radius into the cylindrical skirt surface (12).
    3. Piston according to claim 1 or 2,
      characterised in that,
      the continuous variation of the radiuses of curvature is so selected that an at least approximately logarithmically developing bevel profile (16; 18) is provided at the end regions of the skirt surface (12).
    4. Piston according to claim 1,
      characterised in that,
      the bevel (19; 21) of the skirt surface begins from the piston shaft end with a small radius of curvature (R4; R8), continues with a large, preferably infinite, radius of curvature (R5; R9) with the formation of a conical annular bevel pressure surface (20) and then with again smaller and then increasing radiuses of curvature (R7) transforms into the cylindrical skirt surface with infinite radius of curvature (R2).
    5. Piston according to claim 4,
      characterised in that,
      the conical angle of the bevel pressure surface (20) to the cylindrical skirt surface (12) is smaller than 5°.
    6. Piston according to any preceding claim,
      characterised in that,
      the bevel profile is different at the forward end region and at the rearward end region of the skirt surface of the piston shaft.
    EP97905034A 1996-03-18 1997-02-17 Piston for a hydrostatic axial-piston machine Expired - Lifetime EP0888499B1 (en)

    Applications Claiming Priority (3)

    Application Number Priority Date Filing Date Title
    DE19610595A DE19610595C1 (en) 1996-03-18 1996-03-18 Piston for hydrostatic axial piston engine
    DE19610595 1996-03-18
    PCT/EP1997/000742 WO1997035110A1 (en) 1996-03-18 1997-02-17 Piston for a hydrostatic axial-piston machine

    Publications (2)

    Publication Number Publication Date
    EP0888499A1 EP0888499A1 (en) 1999-01-07
    EP0888499B1 true EP0888499B1 (en) 2002-06-05

    Family

    ID=7788634

    Family Applications (1)

    Application Number Title Priority Date Filing Date
    EP97905034A Expired - Lifetime EP0888499B1 (en) 1996-03-18 1997-02-17 Piston for a hydrostatic axial-piston machine

    Country Status (6)

    Country Link
    US (1) US5970845A (en)
    EP (1) EP0888499B1 (en)
    JP (1) JP2000506585A (en)
    KR (1) KR100382835B1 (en)
    DE (2) DE19610595C1 (en)
    WO (1) WO1997035110A1 (en)

    Families Citing this family (11)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    EP1087136B1 (en) * 1999-09-24 2007-11-14 Kabushiki Kaisha Toyota Jidoshokki Chamfered swash plate compressor piston head
    DE10045281C1 (en) * 2000-09-13 2002-05-23 Orange Gmbh High pressure fuel pump has reduced diameter of piston head corresponding with spacing of heat input from compression cavity
    US6732633B1 (en) * 2003-01-14 2004-05-11 Sauer-Danfoss Inc. Reduced dead volume hollow piston
    DE10312242B3 (en) * 2003-03-19 2004-12-02 Brueninghaus Hydromatik Gmbh Push pin and axial piston machines with this push pin
    JP4828371B2 (en) * 2006-10-23 2011-11-30 ボッシュ・レックスロス株式会社 Axial piston pump / motor
    DE102006052430A1 (en) * 2006-11-07 2008-05-08 BSH Bosch und Siemens Hausgeräte GmbH Compressor with gas-bearing piston
    JP5492917B2 (en) * 2012-02-01 2014-05-14 株式会社豊田自動織機 Variable capacity swash plate compressor
    JP6170330B2 (en) * 2013-04-16 2017-07-26 川崎重工業株式会社 Piston for axial piston pump motor, cylinder block for axial piston pump motor, and axial piston pump motor
    KR102151119B1 (en) * 2014-02-13 2020-09-02 주식회사 두산 Piston of Hydraulic Motor or Pump
    DE102016104238A1 (en) * 2016-03-09 2017-09-14 L'orange Gmbh Pump piston in a high-pressure pump
    DE102017210857A1 (en) 2017-06-28 2019-01-03 Robert Bosch Gmbh Hydrostatic displacement machine, piston for the hydrostatic displacement machine, as well as cylinder drum for the hydrostatic displacement machine

    Family Cites Families (4)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    US3741077A (en) * 1972-04-24 1973-06-26 Eaton Corp Piston assembly
    US4776260A (en) * 1980-11-07 1988-10-11 Vincze Alexander L Constant pressure pump
    DE3609892A1 (en) * 1985-03-26 1986-10-09 Linde Ag, 6200 Wiesbaden Hollow piston for a hydrostatic piston engine and method of manufacturing it
    GB2239304B (en) * 1989-12-22 1994-06-01 Jaguar Cars Torque transfer or reacting mechanism

    Also Published As

    Publication number Publication date
    KR100382835B1 (en) 2003-07-16
    KR20000064432A (en) 2000-11-06
    DE59707424D1 (en) 2002-07-11
    WO1997035110A1 (en) 1997-09-25
    DE19610595C1 (en) 1996-10-10
    EP0888499A1 (en) 1999-01-07
    JP2000506585A (en) 2000-05-30
    US5970845A (en) 1999-10-26

    Similar Documents

    Publication Publication Date Title
    DE69720368T2 (en) scroll compressor
    DE2624849C3 (en) Self-pressure generating radial plain bearing
    EP1013928A2 (en) Swash plate axial piston pump with pulsation damping means
    EP0888499B1 (en) Piston for a hydrostatic axial-piston machine
    DE3539535C2 (en)
    DE2737685A1 (en) WAREHOUSE
    DE3228982C2 (en) Pistons, in particular for internal combustion engines
    DD243732A5 (en) HYDRAULIC SLIDING AXIAL PISTON MACHINE
    DE4237506C2 (en) Axial piston machine
    DE112007002018T5 (en) Hydraulic rotary machine
    DE3210146A1 (en) SLIDE SHOE WASHING UNIT
    DE69929923T2 (en) Axial piston pump and improved valve plate design
    EP0728945B1 (en) Axial piston machine
    DE3319729C2 (en) Piston ring arrangement for hydraulic applications, especially for very high operating pressures
    DE102017208755A1 (en) HYDROSTATIC SUPPORT AND LUBRICATION ON VALV SEGMENT LOAD
    DE2911435B2 (en) Hydrostatic bearing for a radial piston machine
    DE60037009T2 (en) HALF BALL SHOE
    DE102018205010A1 (en) Hydrostatic axial piston machine
    DE2805492C2 (en) Arrangement for cooling the pistons in a hydraulic axial piston machine
    DE2163442A1 (en) Axial piston machine
    CH638590A5 (en) HYDROSTATIC PISTON MACHINE.
    EP0675286A1 (en) Axial piston machine with hydrostatic relief of the rocker body bearing
    DE3041477C2 (en) Pistons and H-shaped piston shoes in radial piston units
    DE3520994A1 (en) HYDRAULIC SCREW MACHINE
    DE2854234A1 (en) CROSS-HEAD PIN BEARINGS FOR PISTON MACHINES, IN PARTICULAR FOR DIESEL ENGINEERING MACHINES

    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

    17P Request for examination filed

    Effective date: 19980306

    AK Designated contracting states

    Kind code of ref document: A1

    Designated state(s): DE FR GB IT SE

    GRAG Despatch of communication of intention to grant

    Free format text: ORIGINAL CODE: EPIDOS AGRA

    GRAG Despatch of communication of intention to grant

    Free format text: ORIGINAL CODE: EPIDOS AGRA

    GRAH Despatch of communication of intention to grant a patent

    Free format text: ORIGINAL CODE: EPIDOS IGRA

    17Q First examination report despatched

    Effective date: 20011113

    GRAH Despatch of communication of intention to grant a patent

    Free format text: ORIGINAL CODE: EPIDOS IGRA

    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

    REF Corresponds to:

    Ref document number: 59707424

    Country of ref document: DE

    Date of ref document: 20020711

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

    Effective date: 20020828

    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: 20030306

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

    Ref country code: SE

    Payment date: 20091222

    Year of fee payment: 14

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

    Ref country code: IT

    Payment date: 20100225

    Year of fee payment: 14

    Ref country code: FR

    Payment date: 20100315

    Year of fee payment: 14

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

    Ref country code: GB

    Payment date: 20100219

    Year of fee payment: 14

    REG Reference to a national code

    Ref country code: SE

    Ref legal event code: EUG

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

    Effective date: 20110217

    REG Reference to a national code

    Ref country code: FR

    Ref legal event code: ST

    Effective date: 20111102

    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: 20110217

    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: 20110228

    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: 20110217

    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: 20110218

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

    Ref country code: DE

    Payment date: 20130426

    Year of fee payment: 17

    REG Reference to a national code

    Ref country code: DE

    Ref legal event code: R119

    Ref document number: 59707424

    Country of ref document: DE

    REG Reference to a national code

    Ref country code: DE

    Ref legal event code: R119

    Ref document number: 59707424

    Country of ref document: DE

    Effective date: 20140902

    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: 20140902