EP0300274B1 - Axial-pistons machine with differential pistons - Google Patents

Axial-pistons machine with differential pistons Download PDF

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Publication number
EP0300274B1
EP0300274B1 EP88110805A EP88110805A EP0300274B1 EP 0300274 B1 EP0300274 B1 EP 0300274B1 EP 88110805 A EP88110805 A EP 88110805A EP 88110805 A EP88110805 A EP 88110805A EP 0300274 B1 EP0300274 B1 EP 0300274B1
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EP
European Patent Office
Prior art keywords
machine according
axial piston
piston machine
piston
passage
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EP88110805A
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German (de)
French (fr)
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EP0300274A1 (en
Inventor
Ludwig Wagenseil
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Hydromatik GmbH
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Hydromatik GmbH
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    • 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
    • F04B5/00—Machines or pumps with differential-surface pistons
    • 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 an axial piston machine according to the preamble of claim 1.
  • the cylinder rooms can be connected to two separate flow lines to e.g. to achieve a throughput distribution, cf. US Pat. No. 3,126,835, or one of the two cylinder spaces, can also only be used to press the piston or pistons against an existing drive inclined surface or an optionally existing cylinder drum against the control mirror, cf. DE-PS 707 462.
  • the cylinder spaces can also be switched as described in US Pat. No. 2,737,899, the larger cylinder space serving as a pre-compression chamber for the smaller cylinder space in order to achieve keise-high pressures without cavitation.
  • the invention has for its object to design an axial piston machine with step piston of the type mentioned in such a way that the relief of the plain bearing depending on the respective operating state of the axial piston machine.
  • the invention is based on the knowledge that, in the known embodiment, a hydrostatic mounting of the pistons on the drive surface due to the fluid cushion as a function of the respective load, i.e. of the axial force with which the piston is pressed against the drive surface is not possible because the pressure force component, which is dependent on the pressure in the second cylinder chamber, is not taken into account.
  • both the pressure in the first cylinder chamber and that in the second cylinder chamber can change for various reasons, e.g. in an axial piston machine with two throughput circuits due to different power consumption of the connected consumers.
  • the drive-side slide bearing of the piston is provided with a second hydrostatic bearing which is independent of the first hydrostatic bearing and which is connected to the second cylinder chamber by a channel and which is therefore effective as a function of the pressure in the second cylinder chamber.
  • the piston forces actually present are thus taken into account to relieve the sliding bearing, which leads to a more balanced hydrostatic bearing of the piston.
  • pressure pockets for three- or multi-stage pistons to be provided in the appropriate number, ie a pressure pocket with a separate connecting channel leading to the associated pressure chamber is to be arranged for each cylinder chamber of the piston.
  • hydrostatic bearings according to the invention on the flat sliding surfaces between a swash plate and a sliding shoe receiving the piston head and / or between the surface of a spherical piston head and the spherical inner surface of a bearing shell or spherical cap receiving the latter.
  • the essential individual parts of the axial piston machine are a housing 4 consisting of a cup-shaped housing part 2 and a housing cover 3, and the cup-shaped housing part 2 or the cavity 5 of the housing 4 passing through the central axis 6 and in the radial wall 7 of the housing part 2 and in the housing cover 3, the drive shaft 8, a cylinder 9 with a plurality of diametrically opposed or star-shaped arranged essentially axially extending piston bores 11, in which correspondingly sized pistons 12 are slidably mounted, which can be driven by an axially displaceable sliding surface 13.
  • the cylinder 9 is formed by a cylinder drum, which is arranged on the drive shaft 8 by means of a central hole and is non-rotatably connected to it by a toothed coupling 14, and, with its end face 15 facing away from the sliding surface 13, bears against a control mirror 16 which bears against a control plate 17 is formed, which is fastened by screws or centering pins to the housing cover 4, in which two supply and discharge lines 18, 19, 21, 22 for the fluid, in the present case oil, are formed.
  • the control plate 17 there are two pairs of opposing, kidney-shaped control channels 23, 24, which correspond to axial flow channels 25, 26, which are connected to the piston bores 11 and the supply and discharge lines 18, 19, 21, 22.
  • the piston bores 11 and piston 12 are step bores and correspondingly dimensioned step pistons, as a result of which first cylinder spaces 27, which are delimited by the end face 28 of the pistons 12, and second cylinder spaces 29, which are delimited by the step surfaces 30 of the pistons 12, are formed are, in each case in the first cylinder space 27, the throughput channel 25 and in the second cylinder space 29, the second throughput channel 26 arranged radially inward from the first throughput channel 25.
  • the pistons 12 have spherical piston heads 32 at their drive-side ends, which are pivotally supported on all sides in the piston heads 32 above and behind-reaching calottes 33 of slide shoes 34.
  • the sliding shoes 34 lie with flat sliding surfaces 35 on the flat inclined surface 36 of a swash plate 37, which is fitted on its drive side with a sliding ring 38 made of wear-resistant material, and whose angle w, which it encloses with a radial transverse plane of the axial piston machine, for the purpose of changing the Throughput volume of the axial piston machine 1 can be changed arbitrarily.
  • the sliding shoes 34 On their side facing the cylinder 9, the sliding shoes 34 have shoulders 39 and, with a projection 41 containing the spherical caps 33, they pass through a retraction plate 42 in holes 43, the shoulders 39 abutting the retraction plate 42, both axially by means of a spherical support head can also be supported radially, which can be acted upon axially against the inclined surface 36 by means of a compression spring (not shown).
  • hydrostatic bearings are formed, in which fluid or oil cushions in communication with the cylinder spaces 27, 29 are connected by recesses through channels 52, 53 formed first and second pressure pockets 54, 55 are effective, which act on the associated piston 12 as a function of the existing pressure in the cylinder spaces 27, 29 against the piston force shown as arrow 58, in order to significantly reduce the latter and thus in the Bearings 49, 51 to reduce the resulting friction.
  • third and fourth pressure pockets 56, 57 in at least one of the spherical sliding surfaces 46, 47, which form hydrostatic bearings for the piston joint 48 due to a corresponding connection with the cylinder spaces 27, 29.
  • the first channel 52 originating from the first cylinder space 27 and the associated first and third pressure pockets 54, 56 and the second channel 53 originating from the second cylinder space 29 as well as the associated second and fourth pressure pockets 55, 57 form separate pressure systems which pass through the sliding surfaces 35, 36, 46, 47 are separated from each other. As a result, the pressure in the associated cylinder space 27 or 29 can only affect the associated hydrostatic pads.
  • a sleeve 61 is inserted axially into each central piston 12 in a central longitudinal bore 62 and fastened to it, for example by pressing, gluing, pinning or screwing, the sleeve 61 having an axial passage through which the swash plate 37 faces away from it Throttle 63 arranged at the end and a channel section 69 (bore) enlarged in cross section compared to the latter.
  • Throttle 63 arranged at the end and a channel section 69 (bore) enlarged in cross section compared to the latter.
  • the sleeve 61 automatically forms the third pressure pocket 56 due to the lack of a spherical shape of its end face.
  • the first channel 52 consists of a section of the longitudinal bore 62, the throttle 63, the channel section 69, the first and the third pressure pockets 54, 56 and a channel section 65 connecting the latter to one another in the sliding block 34.
  • the second channel 53 consists of a radial channel section 66 in the piston 12 in the vicinity of its stepped surface 30, a circumferential groove 67 or taper on the sleeve 61, a channel section 68 and, in the present case, extending radially from the circumferential groove 67 to the fourth pressure pocket 57 in the form of a spherical zone a channel section 70 connecting the pressure pockets 55, 57 to one another, in the present case oblique.
  • the third and fourth pressure pockets 56 and 57 are located in the spherical surface 47 of the piston head 32 and the first and second pressure pockets 54 and 55 are located in the sliding surface 35 of the sliding block 34.
  • the circumferential groove 67 or the distance between the channel sections 66 and 68 is dimensioned smaller than the length 1 of the sleeve 61, so that the latter has sections at its ends with which it is fully and firmly received in the longitudinal bore 62.
  • the first pressure pocket 54 has a circular shape and the second pressure pocket 55 has a circular ring shape, wherein they are arranged concentrically to one another.
  • an annular groove 71 is arranged between them, each at a distance from them, which is connected to the cavity 5 of the housing 4 by a channel 72 extending through the sliding block 34, ie is vented.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Reciprocating Pumps (AREA)
  • Hydraulic Motors (AREA)

Description

Die Erfindung bezieht sich auf eine Axialkolbenmaschine nach dem Oberbegriff des Anspruchs 1.The invention relates to an axial piston machine according to the preamble of claim 1.

Es ist vorgeschlagen worden, aus verschiedenen Gründen den wenigstens einen Kolben einer Axialkolbenmaschine als Stufenkolben auszubilden, wodurch sich zwei Zylinderräume ergeben. Die Zylinderräume können an zwei voneinander getrennte Durchsatzleitungen angeschlossen sein, um z.B. eine Durchsatzmengenaufteilung zu erreichen, vgl. US-PS 3 126 835, oder einer der beiden Zylinderräume kann auch lediglich dazu dienen, den oder die Kolben an eine vorhandene Antriebs-Schieffläche oder auch eine ggf. vorhandene Zylindertrommel gegen den Steuerspiegel zu drücken, vgl. DE-PS 707 462. Die Zylinderräume Können auch, wie in der US-PS 27 37899 beschrieben, in Reite geschaltet sein, wobei der größere Zylinderraum als Vorverdichtungskammer für den kleineren Zylinderraum dient, um auf diese keise serhohe Drüke ohne Kavitation zu erzielen.It has been proposed for various reasons to design the at least one piston of an axial piston machine as a stepped piston, which results in two cylinder spaces. The cylinder rooms can be connected to two separate flow lines to e.g. to achieve a throughput distribution, cf. US Pat. No. 3,126,835, or one of the two cylinder spaces, can also only be used to press the piston or pistons against an existing drive inclined surface or an optionally existing cylinder drum against the control mirror, cf. DE-PS 707 462. The cylinder spaces can also be switched as described in US Pat. No. 2,737,899, the larger cylinder space serving as a pre-compression chamber for the smaller cylinder space in order to achieve keise-high pressures without cavitation.

Zur Verbesserung der Gleitlagerung zwischen dem Kolben und der Antriebsfläche ist es bekannt, zwischen den Gleitflächen ein vom zugehörigen Zylinderraum gespeistes Fluidpolster wie eine Drucktasche zu schaffen, das die Flächenpressung und somit die Reibung und der Verschließ der kolbenseitigen Gleitfläche sowie der Antriebsfläche des Gleitlagers verringert, d.h., eine gewisse Entlastung des Gleitlagers herbeiführt.To improve the sliding bearing between the piston and the drive surface, it is known to create a fluid cushion, fed by the associated cylinder space, such as a pressure pocket between the sliding surfaces, which reduces the surface pressure and thus the friction and closure of the piston-side sliding surface and the drive surface of the sliding bearing, ie , brings about a certain relief of the plain bearing.

Der Erfindung liegt die Aufgabe zugrunde, eine Axialkolbenmaschine mit Stufenkolben der eingangs bezeichneten Art so auszugestalten, daß die Entlastung des Gleitlagers in Abhängigkeit des jeweiligen Betriebszustandes der Axialkolbenmaschine erfolgt.The invention has for its object to design an axial piston machine with step piston of the type mentioned in such a way that the relief of the plain bearing depending on the respective operating state of the axial piston machine.

Diese Aufgabe wird durch die kennzeichnenden Merkmale des Anspruchs 1 gelöst.This object is achieved by the characterizing features of claim 1.

Der Erfindung liegt die Erkenntnis zugrunde, daß bei der bekannten Ausgestaltung eine aufgrund des Fluidpolsters hydrostatische Lagerung der Kolben an der Antriebsfläche in Abhängigkeit von der jeweils vorhandenen Last, d.h. von der axialen Kraft, mit der der Kolben gegen die Antriebsfläche gepreßt wird, nicht möglich ist, weil die vom Druck in der zweiten Zylinderkammer abhängige Preßkraftkomponente unberücksichtigt bleibt. Sowohl der Druck in der ersten Zylinderkammer als auch der in der zweiten Zylinderkammer kann sich jedoch aus verschiedenen Gründen ändern, z.B. bei einer Axialkolbenmaschine mit zwei Durchsatzkreisen wegen unterschiedlicher Leistungsaufnahme der angeschlossenen Verbraucher.The invention is based on the knowledge that, in the known embodiment, a hydrostatic mounting of the pistons on the drive surface due to the fluid cushion as a function of the respective load, i.e. of the axial force with which the piston is pressed against the drive surface is not possible because the pressure force component, which is dependent on the pressure in the second cylinder chamber, is not taken into account. However, both the pressure in the first cylinder chamber and that in the second cylinder chamber can change for various reasons, e.g. in an axial piston machine with two throughput circuits due to different power consumption of the connected consumers.

Bei der erfindungsgemäßen Ausgestaltung ist der antriebsseitigen Gleitlagerung des Kolbens ein vom ersten hydrostatischen Lager unabhängiges zweites hydrostatisches Lager vorgesehen, das durch einen Kanal mit der zweiten Zylinderkammer in Verbindung steht und das somit in Abhängigkeit vom Druck in der zweiten Zylinderkammer wirksam ist. Es werden somit zur Entlastung des Gleitlagers die tatsächlich vorhandenen Kolbenkräfte berücksichtigt, was zu einer ausgewogeneren hydrostatischen Lagerung des Kolbens führt.In the embodiment according to the invention, the drive-side slide bearing of the piston is provided with a second hydrostatic bearing which is independent of the first hydrostatic bearing and which is connected to the second cylinder chamber by a channel and which is therefore effective as a function of the pressure in the second cylinder chamber. The piston forces actually present are thus taken into account to relieve the sliding bearing, which leads to a more balanced hydrostatic bearing of the piston.

Für drei- oder mehrstufige Kolben sind Drucktaschen in der entsprechenden Anzahl vorzusehen, d.h., es ist für jede Zylinderkammer des Kolbens eine Drucktasche mit einem separaten, zur zugehörigen Druckkammer führenden Verbindungskanal anzuordnen.There are pressure pockets for three- or multi-stage pistons to be provided in the appropriate number, ie a pressure pocket with a separate connecting channel leading to the associated pressure chamber is to be arranged for each cylinder chamber of the piston.

Im Rahmen der Erfindung ist es möglich, die erfindungsgemäßen hydrostatischen Lager an den ebenen Gleitflächen zwischen einer Schiefscheibe und einem den Kolbenkopf aufnehmenden Gleitschuh und/oder zwischen der Oberfläche eines kugelförmigen Kolbenkopfes und der sphärischen Innenfläche einer letzteren aufnehmenden Lagerschale bzw. Kalotte auszubilden.In the context of the invention, it is possible to form the hydrostatic bearings according to the invention on the flat sliding surfaces between a swash plate and a sliding shoe receiving the piston head and / or between the surface of a spherical piston head and the spherical inner surface of a bearing shell or spherical cap receiving the latter.

Die in den Ansprüchen 2 bis 11 enthaltenen Merkmale führen zu einfachen und praktikablen Ausgestaltung, die eine einfache und preiswerte Herstellung ermöglichen und eine gute Funktion gewährleisten.The features contained in claims 2 to 11 lead to simple and practical design, which enable simple and inexpensive production and ensure good function.

Nachfolgend wird die Erfindung anhand eines in einer Zeichnung dargestellten bevorzugten Ausführungsbeispiels näher erläutert. Es zeigt:

  • Fig. 1 eine erfindungsgemäß ausgestaltete Axialkolbenmaschine im axialen Schnitt;
  • Fig. 2 die Kolbenanordnung der Axialkolbenmaschine im axialen Schnitt und in vergrößerter Darstellung;
  • Fig. 3 die Gleitfläche eines Gleitschuhs für die Kolbenlagerung in der Draufsicht.
The invention is explained in more detail below on the basis of a preferred exemplary embodiment illustrated in a drawing. It shows:
  • 1 shows an axial piston machine designed according to the invention in axial section;
  • Figure 2 shows the piston arrangement of the axial piston machine in axial section and in an enlarged view.
  • Fig. 3 shows the sliding surface of a sliding shoe for the piston bearing in the plan view.

Die wesentlichen Einzelteile der in Fig. 1 allgemein mit 1 bezeichneten Axialkolbenmaschine sind ein aus einem topfförmigen Gehäuseteil 2 und einem Gehäusedeckel 3 bestehenden Gehäuse 4, eine das topfförmige Gehäuseteil 2 bzw. den Hohlraum 5 des Gehäuses 4 längs der Mittelachse 6 durchsetzende und in der radialen Wand 7 des Gehäuseteils 2 sowie im Gehäusedeckel 3 gelagerten Antriebswelle 8, einem Zylinder 9 mit einer Mehrzahl diametral gegenüberliegend oder sternförmig zueinander angeordneten im wesentlichen axial verlaufenden Kolbenbohrungen 11, in denen entsprechend bemessene Kolben 12 verschiebbar gelagert sind, die durch eine axial verlagerbare Gleitfläche 13 antreibbar sind.The essential individual parts of the axial piston machine, generally designated 1 in FIG. 1, are a housing 4 consisting of a cup-shaped housing part 2 and a housing cover 3, and the cup-shaped housing part 2 or the cavity 5 of the housing 4 passing through the central axis 6 and in the radial wall 7 of the housing part 2 and in the housing cover 3, the drive shaft 8, a cylinder 9 with a plurality of diametrically opposed or star-shaped arranged essentially axially extending piston bores 11, in which correspondingly sized pistons 12 are slidably mounted, which can be driven by an axially displaceable sliding surface 13.

Beim vorliegenden Ausführungsbeispiel ist der Zylinder 9 durch eine Zylindertrommel gebildet, die mittels eines zentralen Loches auf der Antriebswelle 8 angeordnet und durch eine Zahnkupplung 14 drehfest mit dieser verbunden ist, sowie mit ihrer der Gleitfläche 13 abgewandten Stirnseite 15 an einem Steuerspiegel 16 anliegt, der an einer Steuerplatte 17 ausgebildet ist, die durch Schrauben oder Zentrierstifte am Gehäusedeckel 4 befestigt ist, in dem zwei Zuführungs- und Abführungsleitungen 18, 19, 21, 22 für das Fluid, im vorliegenden Falle Öl, ausgebildet sind. In der Steuerplatte 17 sind zwei Paare einander gegenüberliegender, nierenförmiger Steuerkanäle 23, 24 vorhanden, die mit axialen Durchsatzkanälen 25, 26 korrespondieren, die mit den Kolbenbohrungen 11 und den Zu- bzw. Abführungsleitungen 18, 19, 21, 22 in Verbindung stehen.In the present exemplary embodiment, the cylinder 9 is formed by a cylinder drum, which is arranged on the drive shaft 8 by means of a central hole and is non-rotatably connected to it by a toothed coupling 14, and, with its end face 15 facing away from the sliding surface 13, bears against a control mirror 16 which bears against a control plate 17 is formed, which is fastened by screws or centering pins to the housing cover 4, in which two supply and discharge lines 18, 19, 21, 22 for the fluid, in the present case oil, are formed. In the control plate 17 there are two pairs of opposing, kidney-shaped control channels 23, 24, which correspond to axial flow channels 25, 26, which are connected to the piston bores 11 and the supply and discharge lines 18, 19, 21, 22.

Bei den Kolbenbohrungen 11 und Kolben 12 handelt es sich um Stufenbohrungen und entsprechend bemessene Stufenkolben, wodurch erste Zylinderräume 27, die von der Stirnfläche 28 der Kolben 12 begrenzt sind, und zweite Zylinderräume 29, die von den Stufenflächen 30 der Kolben 12 begrenzt sind, gebildet sind, wobei jeweils in den ersten Zylinderraum 27 der Durchsatzkanal 25 und in den zweiten Zylinderraum 29 der sich radial einwärts vom ersten Durchsatzkanal 25 angeordnete zweite Durchsatzkanal 26 mündet.The piston bores 11 and piston 12 are step bores and correspondingly dimensioned step pistons, as a result of which first cylinder spaces 27, which are delimited by the end face 28 of the pistons 12, and second cylinder spaces 29, which are delimited by the step surfaces 30 of the pistons 12, are formed are, in each case in the first cylinder space 27, the throughput channel 25 and in the second cylinder space 29, the second throughput channel 26 arranged radially inward from the first throughput channel 25.

Die Kolben 12 weisen an ihren antriebsseitigen Enden sphärische Kolbenköpfe 32 auf, die allseitig schwenkbar in die Kolbenköpfe 32 über und hintergreifenden Kalotten 33 von Gleitschuhen 34 gelagert sind. Die Gleitschuhe 34 liegen mit ebenen Gleitflächen 35 an der ebenen Schieffläche 36 einer Schiefscheibe 37 an, die an ihrer Antriebsseite mit einem Gleitring 38 aus verschleißfestem Material besetzt ist, und deren Winkel w, den sie mit einer radialen Querebene der Axialkolbenmaschine einschließt, zwecks Veränderung des Durchsatzvolumens der Axialkolbenmaschine 1 willkürlich veränderlich sein kann. Auf ihrer dem Zylinder 9 zugewandten Seite weisen die Gleitschuhe 34 Schultern 39 auf, und sie durchfassen mit einem die Kalotten 33 enthaltenden Vorsprung 41 eine Rückzugplatte 42 in Löchern 43, wobei die Schultern 39 an der Rückzugplatte 42 anliegen, die mittels eines sphärischen Stützkopfes sowohl axial als auch radial abgestützt sein können, der mittels einer Druckfeder axial gegen die Schieffläche 36 beaufschlagt sein kann (nicht dargestellt). In Fig. 3 ist die zwecks Veränderung des Durchsatzvolumens verschwenkbare Schiefscheibe 37 aus Vereinfachungsgründen rechtwinklig zur Mittelachse 6 dargestellt, d.h. Durchsatzvolumen = 0 oder minimal.The pistons 12 have spherical piston heads 32 at their drive-side ends, which are pivotally supported on all sides in the piston heads 32 above and behind-reaching calottes 33 of slide shoes 34. The sliding shoes 34 lie with flat sliding surfaces 35 on the flat inclined surface 36 of a swash plate 37, which is fitted on its drive side with a sliding ring 38 made of wear-resistant material, and whose angle w, which it encloses with a radial transverse plane of the axial piston machine, for the purpose of changing the Throughput volume of the axial piston machine 1 can be changed arbitrarily. On their side facing the cylinder 9, the sliding shoes 34 have shoulders 39 and, with a projection 41 containing the spherical caps 33, they pass through a retraction plate 42 in holes 43, the shoulders 39 abutting the retraction plate 42, both axially by means of a spherical support head can also be supported radially, which can be acted upon axially against the inclined surface 36 by means of a compression spring (not shown). 3 shows the swash plate 37 which can be pivoted for the purpose of changing the throughput volume, for reasons of simplification, at right angles to the central axis 6, i.e. Throughput volume = 0 or minimal.

Jeweils zwischen der Gleitfläche 35 des Gleitschuhs 34 und der Schieffläche 36 der Schiefscheibe 37 sind allgemein mit 49 und 51 bezeichnete hydrostatische Lager ausgebildet, in denen durch Kanäle 52, 53 mit den Zylinderräumen 27, 29 in Verbindung stehende Fluid- bzw. Ölpolster in durch Ausnehmungen gebildeten ersten und zweiten Drucktaschen 54, 55 wirksam sind, die den zugehörigen Kolben 12 in Abhängigkeit von dem vorhandenen Drücken in den Zylinderräumen 27, 29 entgegen der als Pfeil 58 dargestellten Kolbenkraft beaufschlagen, um letztere deutlich zu reduzieren und somit die in den Lagern 49, 51 entstehende Reibung zu senken. Es ist bei einer Abstützung des Kolbens 12 mittels Gleitschuh 34 bei gleichbleibendem Neigungswinkel der Schieffläche 36 möglich, ein Gleichgewicht zwischen der Kolbenkraft 58 und der resultierenden Gegenkraft 59 der Lager 49, 51 zu erzeugen. Die ausgewogene Lagerung ist möglich, weil die Drucktaschen 54, 55 in ihrer axial wirksamen Größe entsprechend groß bemessen sind.Between the sliding surface 35 of the sliding block 34 and the sloping surface 36 of the swash plate 37, hydrostatic bearings, generally designated 49 and 51, are formed, in which fluid or oil cushions in communication with the cylinder spaces 27, 29 are connected by recesses through channels 52, 53 formed first and second pressure pockets 54, 55 are effective, which act on the associated piston 12 as a function of the existing pressure in the cylinder spaces 27, 29 against the piston force shown as arrow 58, in order to significantly reduce the latter and thus in the Bearings 49, 51 to reduce the resulting friction. When the piston 12 is supported by means of a sliding block 34 with the inclination angle of the inclined surface 36 remaining the same, it is possible to create a balance between the piston force 58 and the resulting counterforce 59 of the bearings 49, 51. The balanced storage is possible because the pressure pockets 54, 55 are dimensioned correspondingly large in their axially effective size.

Im Rahmen der Erfindung ist es möglich, auch in wenigstens einer der sphärischen Gleitflächen 46, 47 dritte und vierte Drucktaschen 56, 57 anzuordnen, die aufgrund einer entsprechenden Verbindung mit den Zylinderräumen 27, 29 hydrostatische Lager für das Kolbengelenk 48 bilden.Within the scope of the invention, it is also possible to arrange third and fourth pressure pockets 56, 57 in at least one of the spherical sliding surfaces 46, 47, which form hydrostatic bearings for the piston joint 48 due to a corresponding connection with the cylinder spaces 27, 29.

Der vom ersten Zylinderraum 27 ausgehende erste Kanal 52 sowie die diesem zugehörige erste und dritte Drucktasche 54, 56 und der vom zweiten Zylinderraum 29 ausgehende zweite Kanal 53 sowie die diesem zugehörige zweite und vierte Drucktasche 55, 57 bilden voneinander getrennte Drucksysteme, die durch die Gleitflächen 35, 36, 46, 47 voneinander getrennt sind. Infolgedessen kann sich der Druck im zugehörigen Zylinderraum 27 bzw. 29 nur in den zugehörigen hydrostatischen Polstern auswirken.The first channel 52 originating from the first cylinder space 27 and the associated first and third pressure pockets 54, 56 and the second channel 53 originating from the second cylinder space 29 as well as the associated second and fourth pressure pockets 55, 57 form separate pressure systems which pass through the sliding surfaces 35, 36, 46, 47 are separated from each other. As a result, the pressure in the associated cylinder space 27 or 29 can only affect the associated hydrostatic pads.

Beim vorliegenden Ausführungsbeispiel ist in jedem Kolben 12 axial eine Hülse 61 in eine mittige Längsbohrung 62 eingesetzt und darm befestigt, z.B. durch Einpressen, Kleben, Verstiften oder Schrauben, wobei die Hülse 61 einen axialen Durchgang aufweist, der durch eine an ihrem der Schiefscheibe 37 abgewandten Ende angeordnete Drossel 63 und einen gegenüber letzterer im Querschnitt vergrößerten Kanalabschnitt 69 (Bohrung) gebildet ist. An ihrem dem Kolbenkopf 32 zugewandten Ende bildet die Hülse 61 aufgrund der fehlenden sphärischen Formung ihrer Stirnfläche automatisch die dritte Drucktasche 56.In the present exemplary embodiment, a sleeve 61 is inserted axially into each central piston 12 in a central longitudinal bore 62 and fastened to it, for example by pressing, gluing, pinning or screwing, the sleeve 61 having an axial passage through which the swash plate 37 faces away from it Throttle 63 arranged at the end and a channel section 69 (bore) enlarged in cross section compared to the latter. At its end facing the piston head 32, the sleeve 61 automatically forms the third pressure pocket 56 due to the lack of a spherical shape of its end face.

Der erste Kanal 52 besteht aus einem Abschnitt der Längsbohrung 62, der Drossel 63, dem Kanalabschnitt 69, der ersten und der dritten Drucktasche 54, 56 und einem letztere miteinander verbindender Kanalabschnitt 65 im Gleitschuh 34.The first channel 52 consists of a section of the longitudinal bore 62, the throttle 63, the channel section 69, the first and the third pressure pockets 54, 56 and a channel section 65 connecting the latter to one another in the sliding block 34.

Der zweite Kanal 53 besteht aus einem radialen Kanalabschnitt 66 im Kolben 12 in der Nähe dessen Stufenfläche 30, eine Umfangsnut 67 bzw. Verjüngung an der Hülse 61, ein sich von der Umfangsnut 67 im vorliegenden Fall radial zur kugelzonenförmigen vierten Drucktasche 57 erstreckender Kanalabschnitt 68 und ein die Drucktaschen 55, 57 miteinander verbindender, im vorliegenden Fall schräger Kanalabschnitt 70.The second channel 53 consists of a radial channel section 66 in the piston 12 in the vicinity of its stepped surface 30, a circumferential groove 67 or taper on the sleeve 61, a channel section 68 and, in the present case, extending radially from the circumferential groove 67 to the fourth pressure pocket 57 in the form of a spherical zone a channel section 70 connecting the pressure pockets 55, 57 to one another, in the present case oblique.

Beim vorliegenden Ausführungsbeispiel befinden sich die dritte und die vierte Drucktasche 56 und 57 in der sphärischen Fläche 47 des Kolbenkopfs 32 und die erste und die zweite Drucktasche 54 und 55 in der Gleitfläche 35 des Gleitschuhs 34. Es ist jedoch auch möglich, die Drucktaschen in der jeweils korrespondierenden Gleitfläche auszubilden. Die Umfangsnut 67 bzw. der Abstand der Kanalabschnitte 66 und 68 ist geringer bemessen, als die Länge 1 der Hülse 61, so daß letztere an ihren Enden Abschnitte aufweist, mit denen sie voll und fest in der Längsbohrung 62 aufgenommen ist.In the present exemplary embodiment, the third and fourth pressure pockets 56 and 57 are located in the spherical surface 47 of the piston head 32 and the first and second pressure pockets 54 and 55 are located in the sliding surface 35 of the sliding block 34. However, it is also possible to place the pressure pockets in the to form the corresponding sliding surface. The circumferential groove 67 or the distance between the channel sections 66 and 68 is dimensioned smaller than the length 1 of the sleeve 61, so that the latter has sections at its ends with which it is fully and firmly received in the longitudinal bore 62.

Die Funktion der Axialkolbenmaschine 1 ist allgemein bekannt, und es wird deshalb auf eine Funktionsbeschreibung verzichtet. Zusammenfassend ist zu bemerken, daß aufgrund der gegeneinander abgewogeneren Kolbenkräfte 58 und Gegenkräfte 59 eine reibungsarme und deshalb langlebige Lagerung der Gleitschuhe 34 an der Schiefscheibe 37 und der Kolbenköpfe 32 erreicht wird, und zwar abhängig vom jeweiligen Druck in den Zylinderräumen 27, 29, d.h. abhängig von der aufzubringenden Leistung der Axialkolbenmaschine 1.The function of the axial piston machine 1 is generally known, and a functional description is therefore omitted. In summary, it should be noted that due to the more balanced piston forces 58 and counter forces 59 a low-friction and therefore long-lasting bearing of the sliding shoes 34 on the swash plate 37 and the piston heads 32 is achieved, depending on the respective pressure in the cylinder spaces 27, 29, ie depending on the power to be applied by the axial piston machine 1.

Beim vorliegenden Ausführungsbeispiel hat die erste Drucktasche 54 Kreisform und die zweite Drucktasche 55 Kreisringform, wobei sie konzentrisch zueinander angeordnet sind. Zwecks Verbesserung der Trennung bzw. Abdichtung der Drucktaschen 54, 55 gegeneinander ist beim vorliegenden Ausführungsbeispiel zwischen ihnen eine Ringnut 71 mit jeweils einem Abstand von ihnen angeordnet, die durch einen sich durch den Gleitschuh 34 erstreckenden Kanal 72 mit dem Hohlraum 5 des Gehäuses 4 verbunden, d.h. entlüftet ist.In the present exemplary embodiment, the first pressure pocket 54 has a circular shape and the second pressure pocket 55 has a circular ring shape, wherein they are arranged concentrically to one another. In order to improve the separation or sealing of the pressure pockets 54, 55 from one another, in the present exemplary embodiment an annular groove 71 is arranged between them, each at a distance from them, which is connected to the cavity 5 of the housing 4 by a channel 72 extending through the sliding block 34, ie is vented.

Claims (12)

1. An axial piston machine (1) whose pistons (12) are in the form of differential pistons and delimit a first cylinder space (27) and at least one second cylinder space (29), wherein the pistons (12) are driven on the driving side by an axially displaceable driving surface (13) on which they slide in a sliding contact bearing having a pressure pocket (54, 56) that is connected to the first cylinder space (27) by a passage (52, 63, 65), characterised in that the second cylinder space (29) is connected to a second pressure pocket (55, 57) on one of the two sliding surfaces (35, 36, 46, 47) of the sliding contact bearing by a second passage (53) separate from the first passage (52).
2. An axial piston machine according to claim 1, characterised in that the first and second pressure pockets (54, 55) are formed in the sliding surface (35) of a slipper (34).
3. An axial piston machine according to claim 1 or claim 2, characterised in that the first and second passages (52, 53) run along through the piston (12) for at least part of the length of the piston (12).
4. An axial piston machine according to claim 3, characterised in that the passages (52, 53) run coaxially with one another.
5. An axial piston machine according to claim 3 or claim 4, characterised in that the first and/or second passage (52, 53) run(s) in or is bordered by a sleeve (61) inserted in the piston 12.
6. An axial piston machine according to claim 5, characterised in that the second passage (53) is formed in the region of the said part of the length of the piston (12) by a recess (67) such as a groove, in particular an annular groove, on the outer surface of the sleeve (61).
7. An axial piston machine according to claim 5 or claim 6, characterised in that the recess (67) on the outer surface of the sleeve (61) is connected to the second cylinder space (29) and/or to the second pressure pocket (55) by a transverse passage (66), preferably extending near the step surface (30), and/or by a transverse passage (68) extending in the piston head (32) region.
8. An axial piston machine according to claim 7, characterised in that the transverse passage or passages (66 and/or 68) is or are formed or made as a throttle, or in that a throttle is inserted in the transverse passage (66 and/or 68).
9. An axial piston machine according to any one of claims 1 to 8, characterised in that the piston (12) has a spherical piston head (32) that is pivotably mounted in a spherical cap (33) of a swashplate (37) or of a slipper (34) slideably supported thereon, and the first and second pressure pocket or a third and fourth pressure pocket (56, 57) are located in at least one of the two spherical sliding surfaces (35, 36) of the piston joint (48), preferably in the spherical sliding surface (47) of the piston head (32).
10. An axial piston machine according to any one of claims 1 to 9, characterised in that the second or fourth pressure pocket (55, 57) is arranged concentrically with the first or third pressure pocket (54, 56), preferably surrounding the latter annularly.
11. An axial piston machine according to claim 10, characterised in that between the first and second pressure pocket (54, 55, 56, 57) a recess (71), preferably annular, is provided in one of the sliding surfaces, preferably in that of the slipper (34), which is connected by a passage (72) to the free space (5) inside the housing.
12. An axial piston machine according to any one of claims 3 to 11, characterised in that a throttle (63) is formed on or inserted in the sleeve (63), preferably at the end of the sleeve (61) remote from the swashplate (37).
EP88110805A 1987-07-20 1988-07-06 Axial-pistons machine with differential pistons Expired - Lifetime EP0300274B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873723988 DE3723988A1 (en) 1987-07-20 1987-07-20 AXIAL PISTON MACHINE WHOSE PISTON IS DESIGNED AS A STEPPED PISTON
DE3723988 1987-07-20

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EP0300274A1 EP0300274A1 (en) 1989-01-25
EP0300274B1 true EP0300274B1 (en) 1991-03-20

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US (1) US4852463A (en)
EP (1) EP0300274B1 (en)
JP (1) JP2527993B2 (en)
DE (2) DE3723988A1 (en)

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Also Published As

Publication number Publication date
JP2527993B2 (en) 1996-08-28
JPS6441677A (en) 1989-02-13
DE3723988A1 (en) 1989-02-09
EP0300274A1 (en) 1989-01-25
DE3862076D1 (en) 1991-04-25
DE3723988C2 (en) 1989-06-01
US4852463A (en) 1989-08-01

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