EP3309393B1 - Hydrostatic fluid displacement machine - Google Patents

Description

The invention relates to a method for fastening a sliding bearing component to a sliding partner of a sliding bearing point of a hydrostatic displacement machine with a cylinder drum arranged around an axis of rotation, which is provided with at least one piston recesses, in each of which a piston is arranged to be longitudinally displaceable, the piston being attached to one by means of a support element Stroke-generating raceway is supported, and the cylinder drum is supported in the region of one end face on a housing, the sliding bearing component made of non-ferrous metal, in particular bronze or brass.

In displacement machines of this type, for example axial piston machines or radial piston machines, which can be designed or operated as a pump or motor, it is known to use slide bearing components to reduce the relative movement between two moving components of the displacement machine as a sliding partner of the slide bearing point To incorporate friction and wear. By reducing the friction and wear caused by the sliding bearing components at the sliding bearing points, the efficiency of the displacement machine and its service life are increased. The sliding bearing points can continue to be hydrostatically relieved.

It is known to press or roll a plain bearing bushing into the piston recess of the cylinder drum at a plain bearing point of a generic displacement machine formed by the piston recess and the piston which is longitudinally displaceable therein. The plain bearing bush consists of a non-ferrous metal. The plain bearing bushing reduces friction and wear between the piston and cylinder drum and thus increases the efficiency and service life of the displacement machine. When pressure is applied with high pressure in the displacement space formed by the piston recess and the piston during operation of the displacement machine and the friction of the piston in the piston recess, forces result in the axial direction on the plain bearing bushing. Around To prevent the sliding bearing bush from migrating out of the piston recess in the axial direction, the forces resulting from the application of pressure with the high pressure and the friction of the piston must be less than the holding or clamping forces that result between the sliding bearing bush and the Act with the cylinder drum provided with the piston recess and are created by the press-in process or the rolling-in process of the plain bearing bush. In order to be able to build up sufficient holding or clamping forces without the sliding bearing bush collapsing towards the center axis of the piston recess, a minimum wall thickness of the sliding bearing bushing is required. Different materials are used for the cylinder drum and the plain bearing bush. Due to the different coefficients of thermal expansion of the cylinder drum and the sliding bearing bushing arranged in the piston recess of the cylinder drum, the effect of the sliding bearing bushing collapse is further increased in the event of temperature fluctuations. In addition, the minimum wall thickness required for the plain bearing bushing arranged in the piston recess leads to a reduction in the usable piston diameter and thus the piston area of the piston arranged in the piston recess, which limits the displacement volume of a pump or the displacement volume of an engine. The minimum wall thickness of the plain bearing bushing arranged in the piston recess thus leads to a reduction in the power density of the hydrostatic displacement machine.

At a sliding bearing point of a generic displacement machine formed by the end face of the cylinder drum and a housing-side control plate, it is known to cast or sinter a sliding bearing layer made of a tribologically favorable material, for example a non-ferrous metal, onto the end face of the cylinder drum. However, the pouring or sintering of such a plain bearing layer onto the end face of the cylinder drum causes high manufacturing and manufacturing outlay with correspondingly high costs. In addition, it is already known that the control plate, which is provided with kidney-shaped control geometries for distributing the pressure medium volume flow from an inlet and outlet connection in the housing to kidney-shaped control recesses in the control plate for the piston recesses, is completely made of a sliding bearing material, for example a Non-ferrous metal to run and to arrange this non-ferrous metal control plate between the housing and the cylinder drum and to fasten it to the housing in a rotationally fixed manner. In order to enable the pressure medium volume flow to be distributed in the control recesses of the control plate, an axial minimum thickness of the control plate is required for the integration of the kidney-shaped control geometries. In the case of a massive control plate made of non-ferrous metal, in which the kidney-shaped control geometries are integrated, the required axial expansion of the control plate increases its mass and thus the costs for the raw material of the plain bearing material. In addition, a massive control plate made of non-ferrous metal leads to an increase in the axial installation space of the displacement machine due to the required axial expansion of the control plate.

If a generic displacement machine is provided with sliding shoes, by means of which the pistons are supported on a stroke-generating running surface, for example a fixed swashplate or a swashplate with adjustable inclination, another plain bearing point is formed between the sliding shoe and the running surface. At this plain bearing it is known to solder a plain bearing plate made of a non-ferrous metal onto one end face of the slide shoe. Soldering such a non-ferrous metal circuit board onto the running surface of the sliding shoe, however, results in a high manufacturing and manufacturing effort and thus high costs.

If the displacement machine is designed as a displacement machine with adjustable displacement volume, the track is formed by a swash plate which can be adjusted in the inclined position. A further slide bearing point is formed between the swash plate, which can be adjusted in the inclined position, and a swash plate receptacle of the housing. It is known to arrange a plain bearing shell made of non-ferrous metal at the sliding bearing point between the swash plate and swash plate holder of the housing in order to reduce friction and wear between the housing and the swash plate adjustable in the inclined position. This additional plain bearing shell must be machined precisely from all sides and fixed in the swashplate mount of the housing, for which a pin is used. Such an additional plain bearing shell and its fixation in the housing also cause high costs.

the DE 10 2009 020 109 A1 discloses a generic method in which a plain bearing element made of non-ferrous metal is materially connected to the piston. A thermal joining process, for example welding or soldering, is provided for the material connection of the sliding bearing element to the piston.

the DE 10 2013 203 787 A1 discloses a swash plate machine in which an opening component made of brass or bronze is materially connected to the end face of the cylinder drum and has the bores for connecting the piston recesses to the control plate. The opening component is connected to the cylinder drum by means of welding, in particular laser welding.

the DE 10 2011 011 732 A2 discloses a generic displacement machine in which a plain bearing component made of non-ferrous metal is materially connected to a sliding partner of a plain bearing by explosive plating.

the US 2004/0174014 A1 discloses in Figure 6 the connection of two pipelines by means of a ball joint. The ball joint has an outer hood with a first cylindrical sleeve, the cylindrical sleeve being fastened at the axial end to the first pipeline by means of magnetic pulse welding in order to create a seal, and an inner hood with a second cylindrical sleeve, the cylindrical sleeve is attached to the second pipeline at the axial end by means of magnetic pulse welding to create a seal. In order to achieve a seal in the area of the two hoods, an additional bellows is provided, the first end of which is tightly fastened to the first cylindrical sleeve by means of magnetic pulse welding and the second end of which is tightly fastened to the second cylindrical sleeve by means of magnetic pulse welding.

The present invention is based on the object of providing a generic method for fastening a plain bearing component to a sliding partner of a plain bearing point of a hydrostatic displacement machine, which method is improved with regard to the fastening of the plain bearing component and allows less material to be used for the plain bearing component.

According to the invention, this object is achieved in that the plain bearing component made of non-ferrous metal is materially connected to one of the sliding partners of the plain bearing point by means of magnetic pulse welding. According to the invention, the sliding bearing component is materially connected to the sliding partner of the sliding bearing point by magnetic pulse welding and is thus welded. With magnetic pulse forming, a magnetic pulse is generated, the energy input of which allows several components made of different materials to be welded together with little manufacturing effort, so that a sliding bearing component made of a tribologically favorable material, for example a non-ferrous metal, with a sliding partner made of steel, is possible with little manufacturing effort can be connected to the plain bearing and thus bimetallic components can be manufactured at plain bearing points of a hydrostatic displacement machine with little manufacturing effort.

By means of magnetic pulse welding of the sliding bearing component onto a sliding partner of the sliding bearing point, a planar and cohesive connection of the sliding bearing component with the sliding partner can be achieved with little manufacturing outlay. With magnetic pulse welding, different materials of the sliding bearing component, which enable tribologically favorable properties to reduce friction and wear, can be firmly bonded to different base materials of the sliding partner. Compared to sintering or welding the sliding bearing component onto the sliding partner, the manufacturing and manufacturing outlay for fastening the sliding bearing component can thus be reduced. A steel or cast material can be used as the material of the sliding partner and thus of the component of the displacement machine, onto which the sliding bearing component is welded by means of magnetic pulse welding.

Magnetic pulse welding as a joining method according to the invention for the material-locking fastening of a slide bearing component to a component of a slide bearing point of the displacement machine can be used at all slide bearing points of the displacement machine in order to enable reduced friction and increased wear resistance with little manufacturing and manufacturing effort and with little use of the cost-intensive slide bearing material.

According to one embodiment of the invention, the sliding bearing point is formed by the piston recess of the cylinder drum and the piston as sliding partners, the sliding bearing component being formed by a sliding bearing bushing which is firmly bonded to the piston recess of the cylinder drum as sliding partner by magnetic pulse welding. The plain bearing bushing, which consists for example of a non-ferrous metal, is thus joined into the piston recess of the cylinder drum by means of magnetic pulse welding. By means of magnetic pulse welding of a plain bearing bush in the piston recess of the cylinder drum as a joining process, a materially bonded fastening of the plain bearing bush in the piston recess of the cylinder drum can be achieved. In magnetic pulse welding, the plain bearing material of the plain bearing component welds to the material of the cylinder drum. Compared to fastening a plain bearing bush in the piston recess by rolling in or pressing in, the wall thickness of the plain bearing bush can be significantly reduced, since the holding forces of the plain bearing bush, in order to prevent them from wandering out of the piston bore, are created by welding the plain bearing bush to the cylinder drum and no longer through internal stress the plain bearing bush are generated. With magnetic pulse welding, due to the welding of the plain bearing bushing in the piston recess of the cylinder drum, collapse of the plain bearing bush to the center axis of the piston recess is effectively avoided. Furthermore, with magnetic pulse welding, the wall thickness of the plain bearing bush can be reduced to a few tenths of a millimeter, preferably a maximum of 0.5 mm, with the same functionality. By reducing the wall thickness of the plain bearing bushing, the piston diameter and thus the piston area of the piston can be increased and thus the delivery or absorption volume of the displacement machine according to the invention can be increased. As a result, an increased power density of the displacement machine according to the invention can be achieved.

According to a further embodiment of the invention, the plain bearing is formed by an end face of the cylinder drum and the housing as a sliding partner, the plain bearing component being formed by a plate that is firmly bonded to the cylinder drum or the housing by magnetic pulse welding. With magnetic pulse welding, a plate made of tribologically favorable material can be joined in a simple manner to the end face of the cylinder drum forming a control surface, a material connection or welding of the sliding bearing material to the cylinder drum being achieved. By the Magnetic pulse welding of a circuit board made of tribologically favorable material on the end face of the cylinder drum can achieve a significant reduction in the manufacturing and manufacturing costs for a cylinder drum provided with a plain bearing layer on the end face control surface with the same functionality compared to pouring or sintering a plain bearing layer onto the end face of the cylinder drum will. Alternatively, it is possible by means of magnetic pulse welding, with little manufacturing and manufacturing effort and little use of plain bearing material, to materially attach a plain bearing layer directly to the housing and thus weld it, against which the cylinder drum rests with the end face. If the sliding bearing layer welded onto the housing is provided with kidney-shaped control geometries for distributing the pressure medium volume flow from an inlet and outlet connection in the housing into the piston recesses, there are further advantages in terms of a simple structure and inexpensive manufacture, since there are no pins that position a separate control plate or the Pins receiving holes are required. In addition, the welding of a plain bearing layer on the housing enables the function of a control plate consisting of a non-ferrous metal to be achieved with little axial installation space.

According to a further embodiment of the invention, wherein the support element is formed by a slide shoe arranged on the piston, the slide bearing point is formed by a support element designed as a slide shoe and the raceway, the slide bearing component being formed by a plate which is firmly bonded to the slide shoe by magnetic pulse welding is connected. With magnetic pulse welding, a plate of a plain bearing material, for example a non-ferrous metal, can be firmly joined to a running surface of a sliding shoe, with which a piston is supported on the stroke-generating raceway, with little manufacturing and manufacturing effort. With magnetic pulse welding, a material connection and thus welding between the slide shoe and the slide bearing material is achieved. The plate of the sliding bearing material is preferably joined to the sliding shoe blank, which can then be finished by appropriate mechanical processing. Compared to soldering a slide bearing plate onto a slide shoe blank, with the magnetic pulse welding according to the invention, with the same functionality with regard to a reduction in the Friction and wear reduced manufacturing costs and manufacturing costs can be achieved.

If the track is formed by a swash plate adjustable in the inclined position in order to achieve a variable delivery or absorption volume of the displacement machine, according to a further embodiment of the invention, the slide bearing point can be formed by the swash plate and a swash plate receptacle of the housing of the displacement machine Plain bearing component is formed by a plain bearing shell, which is firmly bonded to the swash plate or with the swash plate receptacle of the housing by magnetic pulse welding. The plain bearing shell is thus connected to the swash plate or, alternatively, to the swash plate mount of the housing by means of magnetic pulse welding. By magnetic pulse welding of a corresponding plain bearing shell on the swash plate or on the swash plate holder in the housing of the displacement machine, a plain bearing with a plain bearing component on the swash plate bearing can also be achieved with little construction and manufacturing effort, in which a small amount of material is used for the plain bearing shell and a complex fixing of a plain bearing shell is no longer required in the housing by means of a pin.

The plain bearing component consists of a non-ferrous metal, in particular bronze or brass. Such materials are characterized by tribologically favorable properties. By means of magnetic pulse welding, however, other plain bearing metals that offer tribologically favorable properties can be joined in a simple manner to a sliding partner, which can consist of a steel material or a cast material, and bimetallic components can be produced.

The displacement machine can be single-stroke or multi-stroke and operated as a pump or motor.

The magnetic pulse welding of a sliding bearing component on a corresponding sliding partner of a sliding bearing can be used when the displacement machine is designed as a radial piston machine or as an axial piston machine. The axial piston machine can be used as a swash plate machine with an axis of rotation rotatably mounted cylinder drum or as a swash plate machine with a track rotatably arranged around the axis of rotation.

Figur 1

eine erfindungsgemäße Verdrängermaschine in einer Seitenansicht,

Figur 2

eine zweite Ausführungsform einer erfindungsgemäßen Verdrängermaschine in einer Seitenansicht.

Further advantages and details of the invention are explained in more detail with reference to the exemplary embodiments shown in the schematic figures. Here shows

Figure 1

a displacement machine according to the invention in a side view,

Figure 2

a second embodiment of a displacement machine according to the invention in a side view.

In the Figures 1 and 2 hydrostatic displacement machines 1 are shown. The illustrated embodiments each show an axial piston machine in swash plate design as an example of a hydrostatic displacement machine 1. Displacement machines 1 according to the invention can be used as an axial piston machine in Bent axis construction or be designed as radial piston machines. The same components are provided with the same reference numerals.

The displacement machine 1 has a cylinder drum 3 rotatably mounted about an axis of rotation 2, which is provided with several piston recesses 4 arranged concentrically to the axis of rotation 2, which are preferably formed by cylinder bores and in each of which a piston 5 is longitudinally displaceable.

The pistons 5 are supported in the area protruding from the cylinder drum 3 by means of a slide shoe 6 as a support element on a stroke-generating track 7 which is formed by a swash plate 8.

The swash plate 8 can be attached to a housing 9 of the displacement machine 1 - as in FIG Figure 1 is shown - be integrally formed or non-rotatably attached, the displacement machine 1 having a fixed displacement volume.

However, it is also possible according to the Figure 2 to arrange the swash plate 8 in a swash plate receptacle 10 of the housing 9 so as to be adjustable in inclination, as a result of which the displacement machine 1 has a variable displacement volume.

The cylinder drum 3 is supported in the axial direction with one end face on a control surface 11 on the housing side. The control surface 11 is provided with kidney-shaped control recesses which enable a suction connection channel 13 and a pressure connection channel 14 in the housing 9 to be connected to the piston recesses 4.

The control surface 11 is in the Figures 1 and 2 formed by a control mirror 15, which according to the Figure 1 can be formed in one piece on the housing 9, for example a housing cover 9a of the housing 9, so that the function of the control surface 11 is integrated into the housing 9, 9a, or according to FIG Figure 2 can be rotatably attached to the housing 9 or the housing cover 9a.

The control surface 11 can as in Figures 1 and 2 be shown flat or spherical.

The pistons 5 are connected to the respective slide shoe 6 by means of a slide shoe joint 20 designed as a ball joint.

The cylinder drum 3 is penetrated by a central bore through which a drive shaft 21 arranged concentrically to the axis of rotation 2 is guided through the cylinder drum 3. The drive shaft 21 is rotatably mounted in the housing 9, 9a by means of bearings 22, 23.

The cylinder drum 3 is non-rotatably connected to the drive shaft 21 by means of driving teeth 24. Also shown is a pressure spring 25 which presses and supports the cylinder drum 3 in the axial direction on the control surface 11.

The displacement machine 1 according to FIG Figure 1 or 2 is provided with slide bearing points at several points at which a relative movement occurs between components, at which a slide bearing component is arranged on one of the two sliding partners to reduce friction and wear. The plain bearing component usually consists of a non-ferrous metal material.

In the Figures 1 and 2 a sliding bearing point G1 is formed between the piston recess 4 in the cylinder drum 2 and the piston 5 arranged therein so as to be longitudinally displaceable. A plain bearing bush 30 is provided as a plain bearing component, which according to the invention is joined into the piston recess 4 by magnetic pulse welding, so that the plain bearing bush 30 is firmly connected to the cylinder drum 3 and the material of the plain bearing bush 30 is welded to the cylinder drum 3.

Another plain bearing point G2 is the displacement machine 1 Figures 1 and 2 between the control plate 15 and in the Figures 1 and 2 formed on the right end of the cylinder drum 2, which forms a control surface on the end of the cylinder drum 2. According to the invention, at this sliding bearing point G2, a disk-shaped plate 31 consisting of a sliding bearing material is joined to the end face of the cylinder drum 2 by means of magnetic pulse welding. The circuit board 31 can alternatively be joined to the corresponding end face of the housing 9, 9a, which forms the control plate 15, by means of magnetic pulse welding.

Another plain bearing G3 with a plain bearing component is the displacement machine 1 Figures 1 and 2 formed between the support element formed by the sliding shoe 6 and the raceway 7 on the swash plate 8. According to the invention, a plate 36 consisting of a sliding bearing material is joined to the sliding shoe 6 by means of magnetic pulse welding onto the running surface of the sliding shoe 6.

In the displacement machine 1 of the Figure 2 a further slide bearing point G4 is shown, at which a slide bearing component is attached to a sliding partner of the slide bearing point G4 by means of magnetic pulse welding.

In the Figure 2 the further plain bearing point G4 is formed on the swashplate mounting between the swashplate 8, which can be adjusted in inclination, and the swashplate receptacle 10 of the housing 9. At this sliding bearing point G4, a sliding bearing shell 35 is connected as a sliding bearing component to the swash plate receptacle 10 of the housing 9 by means of magnetic pulse welding. Alternatively, the plain bearing shell 35 can be connected to the swash plate 8 by means of magnetic pulse welding.

Claims (5)

1. Method for fastening a plain bearing component (30; 31; 35; 36) to a sliding partner of a plain bearing location (G1; G2; G3; G4) of a hydrostatic positive displacement machine (1) with a cylinder drum (3) which is arranged about an axis of rotation (2) and is provided with at least one piston recess (4) in which in each case a piston (5) is arranged in a longitudinally displaceable manner, wherein the piston (5) is supported on a stroke-generating track (7) by means of a supporting element, and the cylinder drum (3) is supported in the region of an end side on a housing (9; 9a), wherein the plain bearing component (30; 31; 35; 36) is composed of non-ferrous metal, in particular bronze or brass, characterized in that the plain bearing component (30; 31; 35; 36) composed of non-ferrous material is connected in a materially bonded manner to the sliding partner of the plain bearing location (G1; G2; G3; G4) by magnetic pulse welding.
2. Method according to Claim 1, characterized in that the plain bearing location (G1) is formed by the piston recess (4) of the cylinder drum (2) and the piston (5) as sliding partners, wherein the plain bearing component is formed by a plain bearing bushing (30) which is connected in a materially bonded manner to the piston recess (4) by magnetic pulse welding.
3. Method according to Claim 1 or 2, characterized in that the plain bearing location (G2) is formed by an end side of the cylinder drum (2) and the housing (9; 9a) as sliding partners, wherein the plain bearing component is formed by a plate (31) which is connected in an integrally bonded manner to the cylinder drum (2) or to the housing (9; 9a) by magnetic pulse welding.
4. Method according to one of Claims 1 to 3, characterized in that the supporting element is formed by a sliding block (6) arranged on the piston (5), and the plain bearing location (G3) is formed by the supporting element, which is configured as the sliding block (6), and the track (7), wherein the plain bearing component is formed by a plate (36) which is connected in a materially bonded manner to the sliding block (6) by magnetic pulse welding.
5. Method according to one of Claims 1 to 4, characterized in that the track (7) is formed by a swash plate (8) which is adjustable in the oblique position, wherein the plain bearing location (G4) is formed by the swash plate (8) and a swash plate receptacle (10) of the housing (9) of the positive displacement machine (1), wherein the plain bearing component is formed by a plain bearing shell (35) which is connected in a materially bonded manner to the swash plate (8) or to the swash plate receptacle (10) of the housing (9) by magnetic pulse welding.

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