Patent Application
20190003466
This application claims priority under 35 U.S.C. § 119 to patent application no. DE 10 2017 210 857.6, filed on Jun. 28, 2017 in Germany, the disclosure of which is incorporated herein by reference in its entirety.
The disclosure relates to a hydrostatic positive-displacement machine, a piston for the positive-displacement machine, and a cylinder drum for the positive-displacement machine.
Hydrostatic positive-displacement machines convert hydraulic power in the form of a product of fluid volumetric flow and pressure into mechanical power in the form of a product of torque and rotational speed, and vice-versa. For the power conversion hydrostatic working chambers of variable volume are required, which are defined by pistons. Here, a piston guided in a cylinder either slides against an inclined plane or is connected to the inclined plane by a ball joint. Both variants rely on supporting the piston against the inclined plane. This principle applies to radial piston machines, for example, to axial piston machines of swashplate design or inclined axis design, to wobble-plate machines and to vane-type machines. A special feature of the latter is that the displacement work is performed not by the stroke of the piston in its cylinder, but by the variation in volume of a positive-displacement chamber, which extends radially between a cylinder drum and an eccentric outer ring, and circumferentially between two pistons guided in the cylinder drum. In radial piston machines the inclined plane is formed by a lifting cam, or more precisely lifting face, along which the piston slides, which is associated with periodic working strokes. An axial piston machine of swashplate design comprises a rotating cylinder drum, in the cylinder bores of which working pistons are received, which on the other side are supported so that they slide on a swashplate. In the case of the axial piston machine of swashplate design said working pistons are connected by a ball joint to an end flange of a drive shaft set towards the axis of rotation of the cylinder drum, so that a rotationally fixed connection is produced between the cylinder drum and the inclined axis.
In each case, because of the inclined plane the pistons and the cylinders must absorb both the axial force acting in the direction of the piston longitudinal axis and a lateral force acting transversely or radially in relation to the piston longitudinal axis. This leads to heavy stressing of the circumferential surfaces of the piston and the associated cylinder, particularly in an area where the piston emerges from the cylinder, and in an area of the end portion of the piston permanently guided in the cylinder. Here high solid contact pressures occur between the tribologically paired piston and cylinder. Said extreme areas of the bearing contact are also referred to as guide runouts.
Such high solid contact pressures can lead to a high degree of wear and power losses. If measures such as high-grade materials and/or heat treatment and coating, for example, are taken to counter the wear, the resulting costs of the positive-displacement machine are high. If, on the other hand, an extended bearing contact, that is to say a larger guide length, is chosen in order reduce the solid contact pressures, this takes up more overall space.
Previously known solutions are guide runouts of the pistons or cylinders which are of rigid or solid design in the area of their runout edges. Disadvantages associated with this are a high weight, greater overall space and possibly increased costs.
In order to reduce the solid contact pressure at the guide runouts, the patent specification DE 10 2006 014 222 B4 proposes a working piston which changes from a cylindrical shape to a spherical shape according to the degree of heating. For this purpose, the working piston comprises a hollow internal space into which an expansion element having a higher coefficient of thermal expansion than the working piston is fitted. If the working piston heats up in operation due to friction, the expansion element expands and presses the outer circumferential surface of the working piston into a convexly spherical shape. In this way the stress loading in the area of the guide runouts is shifted away from a high surface unit pressure towards a greater contact area and a lower surface unit pressure. Disadvantages to this are the high jig/fixture and production engineering costs for the working piston, together with a relatively difficult design of the expansion element and difficulty in matching it to the working piston. Furthermore, this solution works satisfactorily only within a narrow operating range, since the resulting spherical convexity is able to compensate for deformation due to lateral forces only at the design temperature.
Patent specification DE 196 10 595 C1 proposes the application of convex chamfers or radiuses to the piston in the area of the guide runouts, which in principle takes up the idea of spherical convexity. These chamfers or radiuses have a constantly varying radius of curvature, which under the effect of the lateral force discussed leads to a more extensive contact of the tribological pairing in the area of the guide runouts. A disadvantage to this is that in producing the outer circumferential surface of the working piston it is necessary to depart from the easily produced, cylindrical shape, which incurs an increased production cost. Moreover, this type of spherical convexity is “fixed”, regardless of the lateral force actually acting, so that this solution also is capable of optimally reducing the surface unit pressure only within narrow operating ranges.
The object of the disclosure, by contrast, is to create a hydrostatic positive-displacement machine which is better protected against wear. Further objects are to create a piston and a cylinder drum for this positive-displacement machine which each serve to reduce the wear in the area of the guide runouts.
The first object is achieved by a hydrostatic positive-displacement machine as disclosed herein, the second object by a piston as disclosed herein, and the third object by a cylinder drum as disclosed herein. Advantageous developments of the disclosure are described in each of the dependent claims.
A hydrostatic positive-displacement machine comprises a cylinder drum having at least one cylinder, in which a longitudinally displaceable piston is received, which comprises a support portion, which is supported directly or indirectly on an inclined plane of the positive-displacement machine. The piston and its support on the inclined plane therefore in particular form a sliding joint between the cylinder drum and the inclined plane. The support may, in particular, be sliding or alternatively, in particular, rotationally fixed. At the same time an outer circumferential surface portion of the piston is in bearing contact, particularly bearing guide contact, with an inner circumferential surface portion of the cylinder. According to the disclosure, in at least one end area—relative in particular to the stroke direction of the piston—of the bearing contact, a weakening, which serves to reduce a rigidity of the circumferential surface connected to the weakening or a rigidity of a wall arranged between the weakening and the circumferential surface when subjected to a force transversely to the stroke direction, particularly when subjected to a lateral or radial force, is provided on the piston or on the cylinder drum or on both.
The reduced rigidity in the end area of the bearing contact, which may also be referred to as an end area of a piston guide in the cylinder or as a guide runout, serves to increase a deformation of the weakened circumferential surface portion under a given, incident lateral force. In other words, the circumferential surface at this site is less inflexible and due to its more extensive deformation conforms better to the opposing circumferential surface. As a result, a solid contact pressure in this area diminishes. As a result, any friction and in particular any wear there between piston and cylinder as parties to the friction is minimized. An accompanying factor is that the positive-displacement machine is more cost-effective to produce, since lower costs for high-strength materials, heat treatment and coating are incurred. In this way it is also possible to expand the operating parameter range, for example towards a higher power density of the positive-displacement machine. Owing to the reduced wear, less material needs to be used, which leads to a lower weight of the positive-displacement machine and moreover affords an advantage in terms of the overall space, which can result in an increased power density of the positive-displacement machine. The improved deformation serves to increase a surface area between the working cylinder and the working piston on which both a hydrostatic, a hydrodynamic and also a trapped oil-based pressure field can act. The solid friction between the two is thereby reduced compared to the prior art and instead a significantly reduced fluid friction acts on this larger surface area. The effect of this is to achieve a higher efficiency.
The following areas of the piston and the cylinder are possible end areas of the bearing contact or guide runouts, in each of which the weakening can be arranged. Here the references to “inside” and “outside” relate to the reciprocating movement of the piston, “inside” being defined in the inward travel direction and “outside” in the outward travel direction of the piston: an outer guide runout of the cylinder, for example an outer cylinder edge or outer orifice of the cylinder, over which the piston travels or out of which the piston emerges from the cylinder; an inner guide runout of the cylinder, for example an inner cylinder edge arranged in the cylinder; an outer guide runout of the piston, for example an outer piston edge or an outer piston portion, which sinks least into the cylinder or does not sink into the cylinder; an inner guide runout of the piston, for example an inner piston edge or an inner piston portion.
In this way, therefore, one, two, three or up to four guide weakened runouts are formed per cylinder and piston. Here, any combinations of the four said weakened guide runouts are possible.
Possible positive-displacement machines are: a radial piston machine, from the cylinder drum of which the piston emerges radially, the inclined plane being formed by an undulating lifting cam or lifting face, which is arranged radially to the rotor and along which the supported piston slides or rolls; an axial piston machine of swashplate design, from the rotating cylinder drum of which the piston emerges axially, the inclined plane being formed by an upright swashplate, on which the sliding piston is supported; an axial piston machine of inclined axis design, from the rotating cylinder drum of which the piston emerges axially, the inclined plane being formed by a flange of a rotating inclined axis set towards the axis of rotation of the cylinder drum, the piston being rotationally fixed to the flange; a wobble-plate machine, from the upright cylinder drum of which the piston emerges axially, the inclined plane being formed by a rotating swashplate, on which the sliding piston is supported; a vane cell machine, from the cylinder drum of which the piston emerges radially, the inclined plane being formed by a cam ring, which is formed eccentrically or double-eccentrically in relation to the rotor and on which the sliding piston is supported. Here—unlike in the aforementioned positive-displacement machines—a hydrostatic working chamber is not defined in the cylinder drum by the cylinder and its piston, but is defined radially and circumferentially by two pistons, an outside of the cylinder drum and an inside of the cam ring. The work of the vane cell machine results—unlike in the aforementioned machines—not from the reciprocating work of its pistons but from the reciprocating work of the mutually eccentric circumferential surfaces of the cylinder drum and the cam ring.
A development of the positive-displacement machine is designed as a hydrostatic piston machine, in particular as a radial piston machine, axial piston machine or wobble-plate machine, and comprises a cylinder drum having at least one working cylinder, in which a longitudinally displaceable working piston is received. The aforementioned piston is now basically a working piston which—unlike in the vane cell machine—serves for converting power. The working piston here is supported directly or indirectly by a support portion on an inclined plane of the piston machine, so that a rotational movement of the inclined plane can be translated into a stroke of the working piston (pump operation), or vice-versa, a stroke of the working piston into a rotation of the inclined plane (motor operation). The piston machine is, in particular, an axial piston machine of swashplate design, the inclined plane in particular being a swashplate, on which the sliding support portion is supported. Alternatively, the piston machine may be an axial piston machine of inclined-axis design, the inclined plane being a flange of an inclined axis, which is set towards the working piston and the working cylinder and on which the rotationally fixed support portion is supported. Alternatively, the piston machine may be a radial piston machine, the inclined plane being a circumferential lifting face, on which the sliding or rolling support portion is supported. An outer circumferential surface portion of the working piston is in bearing contact with an inner circumferential surface portion of the working cylinder. Apart from these portions the two circumferential surfaces in particular do not come into contact with one another. According to the disclosure a weakening, which serves to reduce a rigidity of the circumferential surface connected to this weakening when subjected to a lateral or radial force, is provided in at least one end area of this bearing contact on the working piston or on the cylinder drum or on both of these.
The reduced rigidity in the end area of the bearing contact, which may also be referred to as an end area of a working piston guide in the working cylinder or as a guide runout, serves to increase a deformation of the weakened circumferential surface portion under a given, incident lateral force. In other words, the circumferential surface at this site is less inflexible and due to its more extensive deformation conforms better to the opposing circumferential surface. As a result, any solid contact pressure in this area diminishes. Consequently, any wear there between working piston and working cylinder as parties to the friction is minimized in this area. An accompanying factor is that the piston machine is more cost-effective to produce, since lower costs for high-strength materials, heat treatment and coating are incurred. In this way it is also possible to expand the operating parameter range, for example towards a higher power density of the piston machine. The overall effect is to achieve an altogether higher efficiency, since owing to a reduced use of material a lower weight of the piston machine can be achieved. Since, as stated, less material needs to be used, due to the reduced wear, this affords an advantage in terms of overall space, which can result in an increased power density of the piston machine. The improved deformation also increases an area on which a hydrodynamic pressure field acts between the working cylinder and the working piston.
In a development at least the one end area comprises an orifice of the working cylinder on the cylinder drum, from which the working piston emerges in the direction of the inclined plane. Alternatively or in addition, at least the one end area may be arranged in the opposite direction inside the working cylinder, where the working piston is run in to an average, submaximal or maximum extent. On the working piston, on the other hand, at least the one end area may be formed by an end portion which is arranged in the working cylinder and/or formed by an end portion which protrudes out of the working cylinder. The weakening according to the disclosure may naturally be provided on more than one such end areas in combination.
In a development at least the one weakening is formed in that it comprises a material different from the surrounding material and having different material characteristics, in particular a lower modulus of elasticity.
In a development at least the one weakening is formed in that it has a heat treatment different from the surrounding material.
In a development at least the one weakening is a topological weakening, for example in the form of a notch. The latter weakening, in particular, can be made in a very targeted way and by simple production engineering means.
Various types of weakening—different material, different heat treatment or topology—may naturally be combined with one another, so that, for example, different guide runouts comprise different types of weakenings.
In a development a wall is formed between the weakening and the circumferential surface. Here the weakening may be specifically adjusted via a thickness of the wall in a transverse or radial direction and a length of the wall in the stroke direction.
In a development the weakening is formed progressively in that the wall extends tapering, particularly in the stroke direction, particularly in the direction of the guide runout. Here the taper may be constant or stepped. It may, in particular, have a parabolic profile.
The positive-displacement machine, in particular a piston machine, is of particularly simple design if the one or both circumferential surfaces, despite the presence of a weakening, is/are of cylindrical formation. It is then possible, compared to the prior art, to dispense with an expensive spherically convex fabrication, for example of the outer circumferential surface of the piston, in particular the working piston. The cylindrical fabrication of the outer circumferential surface and the inner circumferential surface proves less expensive.
In end areas of the circumferential surfaces and/or the bearing contact the circumferential surfaces may comprise chamfers or radiuses or crowns supporting the weakening.
One advantage of the weakening according to the disclosure is that a deformation of the circumferential surface weakened thereby varies as a function of the load.
In a development the weakening extends from a plane or surface angled in relation to the circumferential surface, in particular from an end plane or end surface, in a stroke direction into the working piston or into the cylinder drum. Examples of the end face of the working piston here are the end portion already mentioned, sinking to the maximum extent into the working cylinder and situated opposite this, the end portion of the working piston which protrudes from the working cylinder and at which, for example, the outer circumferential surface terminates. Possibly starting at the latter end portion, for example, is the support portion, which in a preferred development is formed by a ball end of the working piston, which serves to support this on the inclined plane (swashplate, flange of the inclined axis, lifting face, depending on the type of piston machine). For the working cylinder, said end plane or end face is formed, for example, by an end face of the cylinder drum, into which the working cylinder is introduced, for example as a cylinder bore. This end face forms the orifice area of the working cylinder(s), from which the respective working piston emerges. Alternatively or in addition, the end face of the working cylinder may be arranged inside the working cylinder in an area in which the working piston sinks to its average, submaximal or maximum extent. Here the end face may be provided, for example, as an undercut in the form of an annular end face.
In a development, particularly of the topological weakening, the latter comprises a recess. The recess here may be a bore, in particular a blind hole bore, a milling, a groove, a gap or the like. Through the topology of the weakening it is possible to influence the way in which the deformation of the circumferential surface, thus weakened, varies as a function of the load.
In a development the weakening is coaxial, in particular concentric with a central axis of the piston or the cylinder, or alternatively eccentric in relation to the central axis. In the case of the piston a coaxial, concentric weakening, for example, can be provided by means of a central bore in the end portion of the piston arranged in the cylinder. In other words, the piston is hollow at this point. According to the disclosure the weakening may be intensified by additionally forming a circumferential groove and/or a circumferential chamfer on the annular end face produced on the piston in this way. The weakening may be eccentric on the piston, for example, when one or more bores are purposely applied to one of the two said end or annular end faces. Something similar may be provided on the end face of the cylinder drum surrounding the orifice of the cylinder.
In an alternative or supplementary development, the weakening extends asymmetrically or symmetrically in relation to a central axis of the piston or the cylinder, or in relation to a plane spanned by the axis of rotation of the cylinder drum and a piston axis, for example. The asymmetrical weakening purposely caters for cases in which the positive-displacement machine is operated in only one or two operating quadrants, in which the lateral force, resulting from the high pressure of the positive-displacement machine and acting on the piston, is always in the same direction. The asymmetrical variant, on the other hand, recommends itself for the operation of a positive-displacement machine in which a change occurs in the direction of the lateral force resulting from the high pressure. This is the case particularly for a positive-displacement machine in four-quadrant operation with particular quadrant changes.
The weakening may be or comprise a bore, for example, in particular a blind hole bore. This weakening may, in particular, be formed coaxially, in particular concentrically, or eccentrically (as described).
One development having a coaxial, in particular a concentric, weakening is a circumferentially extending groove, for example. The groove here may be formed around part of the circumference (asymmetrical weakening) or all round the circumference (symmetrical weakening).
In principle combinations of multiple, partially circumferential weakenings separated from one another or multiple fully circumferential, interconnected weakenings are possible.
A piston according to the disclosure, in particular a working piston, for a hydrostatic positive-displacement machine, in particular a piston machine, in particular a hydrostatic axial piston machine, which is designed according to at least one aspect of the preceding description, comprises an outer circumferential surface portion which can be brought into bearing contact with an inner circumferential surface portion of a cylinder, in particular a working cylinder of the positive-displacement machine. The piston may be received in the cylinder so that it is displaceable in the stroke direction. The piston moreover comprises a support portion for indirect or direct support on an inclined plane of the positive-displacement machine (swashplate, flange of an inclined axis, lifting face or outer ring, depending on aforementioned type). According to the disclosure a weakening is formed in an area of at least one end portion of the outer circumferential surface portion, relative to the stroke direction. This weakening serves to reduce a rigidity of this end portion when subjected to a lateral or radial force. The advantage to this is that the working piston according to the disclosure can be inserted into an existing positive-displacement machine or replaced. For a small outlay, therefore, an existing system can be adapted, reducing the wear between the piston and the cylinder of the positive-displacement machine in the manner described and even expanding an operating parameter range of the positive-displacement machine.
A cylinder drum according to the disclosure for a hydrostatic positive-displacement machine, in particular a piston machine, in particular a hydrostatic axial piston machine, which is designed according to at least one aspect of the preceding description, comprises at least one cylinder, in particular a working cylinder, in which a piston, in particular a working piston, of the positive-displacement machine can be received so that it is displaceable in the stroke direction. The piston in this case may obviously be the piston according to the disclosure, but also alternatively a conventional piston. The piston can be supported by a support portion on an inclined plane of the positive-displacement machine. According to the disclosure the cylinder of the cylinder drum is provided with an inner circumferential surface portion which is intended for bearing contact on an outer circumferential surface portion of the piston. Here, for reducing the rigidity, as already repeatedly discussed, a weakening is formed in an area of at least one end portion of the circumferential surface portion. This leads to a reduction in the rigidity of the end portion when subjected to a lateral or radial force. A recitation of the advantages afforded by the weakening according to the disclosure will be dispensed with here.
The weakening according to the disclosure may be applied to any piston and its cylinder in which it is guided. More generally, it may be applied to any sliding joint that comprises a guide element (cylinder) and a guided reciprocating element (piston) longitudinally displaceable therein. Featured here in particular, for example, are a cylinder and a piston of a hydrostatic adjusting device of said positive-displacement machine. The applicant reserves the right to address a set of claims to a sliding joint weakened in this way, in particular to an adjusting device weakened in this way.
An exemplary embodiment of a hydrostatic axial piston machine according to the disclosure, multiple exemplary embodiments of a cylinder drum according to the disclosure and a working piston according to the disclosure are represented in the drawings. The disclosure is now explained with reference to the figures of these drawings, of which:
A swivel angle of the cradle 32 is hydraulically adjustable via a hydrostatic adjusting device 34. A return device in the form of a spring 36 acts on the cradle 32 in opposition to the adjusting device 34. Added to this is a restoring moment resulting from the propulsive forces. In the unpressurized operating state, for example in starting, and with the adjusting device inoperative, this deflects the swashplate in the direction of a maximum swivel angle.
In the working cylinders 22 hydrostatic working chambers 38 are defined by the working pistons 24. At an end face of the cylinder drum 16 remote from the swashplate 20 these chambers each comprise an aperture 40, said end face being in bearing contact with a control plate 42 fixed to the housing. This control plate comprises passages in the form of reniform openings 44, which are each in constant hydraulic connection with one of the hydrostatic working connections of the housing cover 6 (not shown). Further details of the basic construction of the axial piston machine 1 can be dispensed with, since this technology is sufficiently known from the prior art.
In operation of the axial piston machine 1, assuming operation as a pump, a torque is transmitted to a shaft stub 46 of the drive shaft 8. This starts to rotate and the cylinder drum 16 turns with it. If the swashplate 32, as shown, is swiveled out of a neutral position, a working stroke, the dead centers of which are shown top and bottom in
In a suction stroke between the dead center represented at the top and the dead center represented at the bottom, fluid is drawn in at the low-pressure connection (not shown) of the housing cover 6 by the working piston 24 running out of its working cylinder 22. This can happen in the pump operation discussed, since the sliding shoes 28 are forced onto the swashplate 30 by a hold-down device 47. This is followed, from the dead center represented at the bottom of
This and further exemplary embodiments of a working piston, together with a cylinder drum according to the disclosure are explained in more detail in the following figures.
In order to also safeguard the axial piston machine against wear to other heavily stressed components, according to
The cylinder drums according to the disclosure will first be described with reference to
As already mentioned, one problem particularly with highly-stressed piston machines with high working pressures is that the surface contact pressure in said end areas 48 and 50 according to
According to one exemplary embodiment shown in
The exemplary embodiment according to
An undercut in the working cylinder, over which the piston does not pass, is feasible as a further embodiment.
An embodiment in which the entire outer circumferential surface of the working piston is always inside the working cylinder, that is to say it never emerges from the working cylinder, is also possible. The optimum longitudinal guidance would be achieved here. Since this is difficult to achieve in practice, however, the weakening in the area of the orifice is to be recommended in cases where the outer circumferential surface of the working piston emerges, as is shown in
The geometrical ratios in the area of the weakening, and the weakening itself are preferably designed by FEM or EMD. The design process in particular produces geometrical ratios or dimensional ranges, a cross sectional profile of the wall 62 according to the required maximization of the contact surface.
Unlike the working piston 124 according to
The exemplary embodiment according to
The exemplary embodiment according to
In the case of the wall 62 that remains between the respective circumferential surface 60; 61 and the weakening 58; 158; 258; 358; 458; 558; 658; 758; 858; 958; 1058, care must be taken in the event of a subsequent heat treatment to ensure that it is of sufficient thickness, so that full hardening cannot ensue, thereby preventing brittle fracture at this point.
Wear can further be reduced if the circumferential surface (inner circumferential surface or outer circumferential surface) connected to the respective weakening is additionally provided with a micro-contouring, so that a converging contact gap results in the end area. In principle the wear can also be reduced by the creation of a more wear-resistant tribology. This can be done through the choice of material, a heat treatment, a coating, for example carbon-coating, or by the choice of a fluid improved by additives, for example. Wear can also be reduced by improving the surface quality of the working piston and working cylinder as said tribological pairing. Cooling, lubricant and relief pockets offer another general approach to cooling, lubrication and pressure relief by means of the fluid used. An optimization of the piston clearance between the working piston and the working cylinder can also reduce the wear. The same applies to an increase in the guide container, so that the bearing contact, that is to say the overlap of the outer circumferential surface portion and the inner circumferential surface portion is increased. Then the guidance of the working piston in the working cylinder is extended and the surface contact pressure in the end areas is reduced. Further advantages are afforded, for example, by using an insertable liner, especially one made of brass, to form the inner circumferential surface of the working cylinder.
In addition to the weakening according to the disclosure a reduction in the rigidity can be achieved by other design measures. For example, guide runouts of the piston and/or working cylinder can be designed to match one another, so that they cannot come into contact. A radially widened clearance cut or undercut in the working cylinder is feasible, for example, which in the stroke direction is of such long dimensions that the inner end portion of the piston moves exclusively in the clearance cut or undercut throughout its entire stroke. In this way the inner piston edge has no contact with the working cylinder and the wear-intensive “scraping” of the inner piston edge on the inner circumferential surface of the cylinder is impossible. This solution is appropriate, for example, if the guide situation of the working piston in the working cylinder is not thereby critically impaired due to a resulting, shorter guide length or by diverging guide clearances.
In principle any combination of the exemplary embodiments of weakenings is possible.
A hydrostatic positive-displacement machine is disclosed, in particular a piston machine, in particular an axial piston machine of swashplate design, having a cylinder drum, in at least the one cylinder, particularly working cylinder, of which, a piston, in particular working piston, subjected to lateral forces, is axially guided. Here an inner circumferential surface of the cylinder and an outer circumferential surface of the piston each comprise a guide portion, the guide portions being the portions of the two surfaces which come into bearing contact with one another. According to the disclosure at least one end area of at least one of the guide portions comprises a weakening, which serves to reduce its rigidity in respect of stress loading by a lateral force.
A piston is moreover disclosed, in particular a working piston, for a positive-displacement machine, in particular a piston machine, at least one end area of its guide portion comprising a weakening, which serves to reduce its rigidity in respect of stress loading by a lateral force. A cylinder drum is also disclosed having at least one cylinder, in particular a working cylinder, for receiving a piston, in particular a working piston, at least one end area of a guide portion of the cylinder comprising a weakening, which serves to reduce its rigidity in respect of stress loading by a lateral force.
1 hydrostatic axial piston machine
2 housing
4 housing canister
6 housing cover
8 drive shaft
10 rolling-contact bearing
12 housing base
14 rolling-contact bearing
16;116;216; cylinder drum
316;416;516;
616;716;816
18 axis of rotation
20 piston longitudinal axis/pitch circle
22 working cylinder
23 chamfer
24;124;224; working piston
324;424;524
25 shoulder
26 piston head
27 piston neck
28 sliding shoe
30 swashplate
32 cradle
34 adjusting device
36 return device
38 hydrostatic working chamber
40 aperture
42 control plate
44 passage
46 shaft stub
47 hold-down device
48,50 end area
49 return ball
51;651 end face
52 orifice
54;154 internal toothing
56 external toothing
58;158;258; weakening
458;558;658;
758;858;1058
60 inner circumferential surface
61 outer circumferential surface
62 wall
64 hollow bore
66 passage
68 shoulder
70,72 inner chamfer
659 axial recessing tool
674;774;874 clearance cut
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 210 857.6 | Jun 2017 | DE | national |
