EP0433730A1 - Axial piston machine with swash plate - Google Patents

Abstract

The invention relates to an axial piston machine in a swashplate design, the swashplate through which the drive shaft passes can be pivoted about an effective swivel axis in such a way that its active surface supporting the piston has a radial movement component with respect to the drive shaft during swiveling, in the direction of which the effective swivel axis during the swashplate Swiveling shifted in parallel. In order to adjust the swash plate to a larger swivel angle, the invention provides for the effective swivel axis (26) to be adjusted radially in a direction opposite to the direction of the radial movement component (R) of the swash plate active surface (19). <IMAGE>

Description

The invention relates to an axial piston machine in a swashplate design according to the preamble of claim 1.

Such an axial piston machine is known from DE-OS 37 33 083, the swash plate of which is pivotally supported on the housing via a pivot bearing off-center of the drive shaft axis. The swivel bearing consists of housing support surfaces which are radial with respect to the drive shaft and convex projections supported by them on the rear of the swash plate, which is opposite the active surface supporting the pistons. The contact surfaces between the convex projections and the housing support surfaces define the effective pivot axis about which the swash plate can be pivoted. Due to the arrangement of the swivel bearing off-center of the drive shaft axis and at the distance corresponding to the swashplate thickness from the swashplate effective surface, the swashplate swiveling has a radial movement component directed in such a way that a reduction in distance between the inner swashplate edge of the swashplate part rising from the housing support surfaces and the drive shaft enters. The theoretically maximum achievable swivel angle is reached when the distance is reduced to 0. In the known axial piston machine, however, this reduction in distance is greater than the amount of the aforementioned radial motion components, namely by the amount of a further radial motion component in the same direction, which results from the fact that during the swashplate pivoting, the convex projections to avoid sliding friction on the housing - Roll support surfaces in the direction of the drive shaft axis and the effective Consequently, the pivot axis is shifted in the same direction. Accordingly, the maximum pivot angle that can actually be achieved is less than the arrangement of the pivot bearing relative to the drive shaft axis and to the swashplate effective surface corresponds.

It is an object of the invention to develop an axial piston machine of the type mentioned at the outset such that its swash plate can be adjusted to a larger swivel angle.

This object is achieved in that the effective pivot axis is radially adjustable in a direction opposite to the direction of the radial movement component of the swashplate effective surface. In this way, according to the size of the radial adjustment of the effective pivot axis, the inner swash plate edge which approaches or more closely approaches the drive shaft during the pivoting is withdrawn from the drive shaft. This withdrawal is directly converted into an increase in the swivel angle. The reduction in distance can be completely eliminated or even reversed in an increase in distance. With the solution according to the invention, with full use of the swash plate through-hole penetrated by the drive shaft, i.e. without enlarging the same and thus without sacrificing strength, swivel angles greater than 20 ° can be set.

The solution according to the invention can be applied to all axial piston machines in a swashplate design, that is to say to machines whose swashplates are mounted both outside the plane of their active surface in the center or off-center to the drive shaft axis and in the plane of their active surface off-center of the drive shaft axis. In the latter case, when swashing the swash plate, both of them approach each other from one to the effective swivel axis vertical straight cut sections of the inner swashplate edge of the drive shaft, the section further away from the swivel axis to a greater extent than the closer one. In such a case, the radial adjustment of the effective pivot axis takes place counter to the direction of the radial movement component of this section which is further away from the effective pivot axis. The solution according to the invention is also applicable to axial piston machines whose swash plate can be pivoted in both directions, ie from -V to + V.

According to an advantageous development of the invention, the effective swivel axis can be adjusted radially simultaneously with the swashplate swiveling and preferably by the same. This enables swashplate swiveling to be carried out quickly and easily.

Advantageously, the swash plate is pivotally supported on the housing of the axial piston machine via a swivel bearing arrangement defining the effective swivel axis, the swivel bearing arrangement being guided radially displaceably on the housing in a guide arrangement extending in the direction of the radial movement component of the swash plate active surface. The guide arrangement can comprise two guides arranged at a mutual distance and the swivel bearing arrangement two swivel hemispheres, each guided in one of the guides, as well as two half-shells mounted on the swash plate and formed thereon.

Preferably, the swash plate is rotatable about two pivots parallel to the effective swivel axis in two formed on opposite housing parts, each running in a plane perpendicular to the effective swivel axis, which extend in such a way that they move along the swash plate pivoting of the pivot bearing arrangement Guide arrangement with the Forcing the direction of the radial movement component of the swashplate effective surface in the opposite direction.

According to a development of the invention, the effective swivel axis is arranged outside the plane of the swashplate effective surface, it being able to intersect the drive shaft axis when the swashplate is in the zero position. In addition, the axis of rotation of the pivot pin can intersect the drive shaft axis when the swash plate is in the zero position, so that with positive guides running parallel to the drive shaft axis, the swash plate in both possible directions, i.e. both clockwise and counterclockwise, can be pivoted with the radial adjustment according to the invention of the effective pivot axis.

To swivel the swash plate in one direction, it is advantageous if the axis of rotation is arranged to the side of the drive shaft axis when the swash plate is in the zero position and / or the positive guides run at an angle to the drive shaft axis, preferably in the direction of the effective swivel axis when the swash plate is in the zero position. The guide angle can be substantially the same as the swivel angle of the swash plate that is fully swiveled out.

According to another development of the invention, when the swashplate is in the zero position of the swashplate, the effective swivel axis is arranged to the side of the drive shaft axis, as a result of which swashplate swivel is preferably also achieved in one of the two directions, for example under the action of the hydraulic piston force.

Each pivot is advantageously mounted in a sliding block guided in each positive guidance.

According to a development of the invention, the pivotable arrangement with hydrostatic support is mounted in the guide arrangement. For this purpose, it is favorable if at least one through-channel connects through each swivel hemisphere a groove formed in its flat sliding surface with a groove formed in its spherical sliding surface. At least one transverse channel can be provided in each swivel hemisphere, which connects a further groove formed in its spherical sliding surface to the through channel.

For the supply of lubricating oil to the grooves in the flat sliding surfaces of the swivel hemispheres, a lubricating oil line opening into the guides is advantageously provided in the housing. The lubricating oil can also be supplied via a longitudinal bore in the adjustment device and connected transverse bores in the swash plate, the transverse bores opening into one of the grooves in the spherical sliding surfaces of the swivel hemispheres. An intermittent supply of lubricating oil from the cylinder bores is preferably carried out via an axial bore through the pistons, the ball heads and the sliding shoes and a through bore leading to the swivel hemispheres in the swash plate, which is on the one hand in the half-shells in the area of the grooves and on the other hand in the swash plate Effective area opens out on the slide shoe track.

Fig. 1

einen Längsschnit der erfindungsgemäßen Axialkolbenmaschine gemäß dem bevorzugten Ausführungsbeispiel mit einer in der Nullstellung befindlichen Schrägscheibe,

Fig. 2

einen Längsschnitt der Axialkolbenmaschine nach Fig. 1 mit vollständig ausgeschwenkter Schrägscheibe,

Fig. 3

einen Schnitt entlang der Linie III-III in Fig. 2,

Fig. 4

eine schematische Darstellung der Schrägscheibe in der Nullstellung und in der völlig ausgeschwenkten Stellung gemäß der Erfindung sowie die maximal erzielbare Schwenkstellung der Schrägscheibe ohne Anwendung der erfindungsgemäßen Lösung, und

Fig. 5

eine schematische Darstellung der Schmierölzufuhr zur Schrägscheibe.

The invention is described in more detail below on the basis of a preferred exemplary embodiment with reference to the drawing. Show it

Fig. 1

2 shows a longitudinal section of the axial piston machine according to the preferred embodiment with a swash plate in the zero position,

Fig. 2

2 shows a longitudinal section of the axial piston machine according to FIG. 1 with the swash plate fully swung out,

Fig. 3

2 shows a section along the line III-III in FIG. 2,

Fig. 4

a schematic representation of the swash plate in the zero position and in the fully pivoted position according to the invention and the maximum achievable swivel position of the swash plate without using the solution according to the invention, and

Fig. 5

is a schematic representation of the lubricating oil supply to the swash plate.

The axial piston machine shown in the drawing comprises a cup-shaped housing 1, a drive shaft 2 with a drive shaft axis 3, a cylinder block 4, a swash plate 5 and a control or distributor body 6.

The housing 1 has an essentially square cross section and has a housing base 7 and four adjoining housing walls 8, on the free ends of which a housing cover 9 is detachably fastened.

The drive shaft 2 protrudes through a through hole in the housing base 7 into the interior of the housing 1 and is rotatably supported by a roller bearing 10 in this through hole and, not shown, in a blind hole in the housing cover 9. The drive shaft 2 passes through a central through-bore of the distributor body 6, the cylinder block 4 and the swash plate 5 in the interior of the housing 1.

The distributor body 6 is fastened to the housing cover 9 and is provided with two through openings in the form of kidney-shaped control slots 11, each of which is connected to a suction or pressure port, not shown, of the axial piston machine. The spherical control surface 12 of the distributor body 6 facing away from the housing cover 9 also serves as an axial bearing surface for the cylinder block 4.

The cylinder block 4 is non-rotatably connected to the drive shaft 2 by means of a keyway connection 13 and has axially parallel cylinder bores 14 which are arranged uniformly on a partial circle coaxial with the drive shaft axis and open out freely via outlet channels 15 on the axial cylinder block bearing surface facing the distributor body 6. The mouth channels 15 are arranged on the same pitch circle as the control slots 11. Pistons 16, which are guided axially displaceably within the cylinder bores 14, are provided at their ends facing the housing base 7 with ball heads 17, which are mounted in sliding shoes 18 and are supported by these on an active surface 19 of the swash plate 5 supported on the housing base 7. Channels 38, which run axially through the pistons 16 and the sliding shoes 18 and are only indicated in the latter, supply the sliding surfaces between the ball heads 17 and the sliding shoes 18 and the path of the latter on the swashplate active surface 19 with lubricating oil.

A compression spring 20, which is supported on the cylinder block 4 within its through bore and surrounds the drive shaft 2, presses on the slide shoes 18 via pressure pins 21, a print head 22 and an annular pressure disk 23 and thus holds them in contact with the active surface 19 of the swash plate 5. The print head 22 of spherical cut-out shape is attached to a sleeve-like extension of the cylinder block 4 and penetrated by the drive shaft 2. The thrust washer 23 is movably supported with its inner edge on the outer surface of the print head 22 and is in contact with slide shoe protrusions 25 with bores 24 engaging around free end sections of the slide shoes 18.

The swash plate 5 is about a swivel bearing arrangement Effective pivot axis 26 is pivotally supported on the housing base 7 off-center of the drive shaft axis 3, that is to say offset to the left in accordance with the drawing. The swivel bearing arrangement consists of two swivel hemispheres 27 and two half shells 28 mounted on them, which are formed in mutually opposite edge regions of the swashplate rear side opposite the swashplate active surface 19. The effective pivot axis 26 is defined by the two centers of the pivot hemispheres 27. These swivel hemispheres 27 are each displaceably guided in a radial guide 29, which is radial with respect to the drive shaft 2 and perpendicular to the effective swivel axis 26 and is only indicated in the drawing, in the housing base 7. In the non-swung-out position or zero position of the swash plate 5, as shown in FIG. 1, its active surface 19 extends radially to the drive shaft axis 3; in addition, as can be seen in FIG. 1, the central through-bore 30 of the swash plate 5 is arranged off-center of the drive shaft axis 3, ie shifted to the right in FIG. 1. The central through bore 30 is essentially elliptical, its larger diameter extending perpendicular to the effective pivot axis 26 and allowing the swash plate 5 to be pivoted into the maximum pivot position shown in FIG. 2.

An adjusting device 31 in the form of a rod which can be displaced in the direction of the housing base 7 by a drive (not shown) is mounted in a nose which is attached laterally to the swash plate 5.

As shown schematically in FIG. 4, the swashplate active surface 19 or a point P lying on it has a radially directed movement component R, which indicates the swashplate active surface, when the swashplate 5 is pivoted about the effective pivot axis 26, as indicated by an arrow V. 19 laterally to the right in FIG. 4 shifts until the point S located on it, in which the larger diameter of the central through bore 30 intersects its inner edge 32, bears against the drive shaft 2 in the position S 'and thus prevents further swiveling of the swash plate 5 beyond the swivel angle α obtained.

However, in order to enable a greater swiveling of the swash plate 5 up to the swivel angle β in FIG. 4, a positive guidance arrangement is provided which, when swashing the swivel plate of the effective swivel axis 26, has a radial movement RE with respect to the drive shaft 2 with a direction of the radial movement component R. the swashplate effective surface 19 forces opposite direction. For this purpose, two parallel positive guides 33 are formed in the housing walls 8 cut by the effective pivot axis 26, in which the swash plate 5 is rotatably guided in each of a sliding block 35 with a pivot 34 running parallel to the effective pivot axis 26.

The pivot pins 34 are located on the right-hand side of the drive shaft axis 3 in FIG. 4, both when the swash plate 5 is not swung out and when it is fully swiveled out. The constrained guides 33 run so obliquely at a guide angle β 'to the drive shaft axis 3 that their longitudinal center axes 36 meet extend into the fourth quadrant Q of an imaginary coordinate system xy, the coordinate origin of which lies on the axis of rotation 37 of the pivot pin 34 and the y axis of which runs parallel to the drive shaft axis 3. The effective pivot axis 26 is arranged in the fourth quadrant Q. When the swash plate 5 is not swiveled out, the longitudinal center axes 36 of the positive guides 33 run in the direction of the effective pivot axis 26. As shown in FIG. 4, the guide angle β 'of the forced guides 33 is equal to the swivel angle β which is complete swung-out swash plate 5. The positive guides 33 can also run parallel or in other directions obliquely to the drive shaft axis 3, such as in the direction of the first quadrant, the radial adjustment path of the effective swivel axis 26 being limited depending on the size of the guide angle β '.

Just like the swivel hemispheres 27 in the guides 29, the ball heads 17 in the slide shoes 18 are supported hydrostatically on the active surface 19 of the swash plate 5. According to a first embodiment, the lubricating oil required for hydrostatic support is supplied from the cylinder bores 14 via axial bores 38 in the pistons 16, the ball heads 17 and the sliding shoes 18 (only shown in the latter). From the latter there is an intermittent supply of lubricating oil to the swivel hemispheres 27 via a through hole 39 through the swash plate 5 and an adjoining through channel 40 in the swivel hemispheres 27, which has a groove 41 in the spherical surface with a groove 41 in the sliding surface of the respective swivel hemisphere 27 connects. Cross channels 42 branching off from the through channels 40 open out into further grooves in the spherical surfaces of the swivel hemispheres 27.

Instead of supplying the lubricating oil from the cylinder bores 14, according to a second embodiment, the lubricating oil can be supplied to the swivel hemispheres 27 via lubricating oil lines 43 to the guides 29 and thus to the grooves 41 in the sliding surfaces of the swivel hemispheres 27. According to a third embodiment, the lubricating oil supply can take place through a longitudinal bore 44 in the adjusting device 31 and adjoining transverse bores 45 through the swash plate 5. The transverse bores 45 open out in the grooves 41 in the spherical surfaces of the swivel hemispheres 27.

The axial piston machine according to the invention can be known Be operated both as a motor and as a pump. Their function is described below only with reference to the radial adjustment of the effective swivel axis according to the invention:
As a result of the drive shaft axis 3 passing eccentrically through the center of the pitch circle of the cylinder bores 14, the swash plate 5 is acted upon more strongly on its right side in FIG. 1 than on its left side by the oil pressure and the force of the compression spring 20 and is acted upon on it Way in the fully pivoted position shown in Fig. 2 held. The adjustment of the axial piston pump to a lower delivery volume up to the zero position with zero delivery shown in FIG. 1 is carried out by applying force to the adjusting device 31 on the housing base 7. If, starting from this zero position, the application of force to the adjusting device 31 is reduced, the swash plate 5 pivots counterclockwise about the effective pivot axis 26, as indicated by the arrow V in FIG. 4. During this swiveling movement, a radial force component directed to the left in FIG. 4 is exerted on the swiveling hemispheres 27 by the constrained guides 33 via the swash plate 5 and this or the effective swiveling axis 26 is thus subjected to a movement RE along the guides 29 with a sense of direction of the radial movement component R of the swashplate active surface 19 in the opposite direction. As a result, the radial movement of the point S of the swashplate inner edge 32 in the direction of the drive shaft 2 during the swashplate pivoting is superimposed by an opposite radial movement, so that the approach of this point S to the drive shaft 2 is reduced and, accordingly, the swashplate 5 is reached of the pivot angle β can be pivoted. In this swivel position, the point S is in the position S ″ and the effective swivel axis 26 in the position 26 ′. When the swash plate 5 is pivoted in the direction of the zero position, the effective swivel axis 26 in FIG.

Claims (23)

Axial piston machine in swashplate design, the swashplate through which the drive shaft passes can be pivoted about an effective swivel axis in such a way that its active surface supporting the piston has a radial movement component with respect to the drive shaft during swiveling, and the effective swivel axis is shifted during swashplate swivel,
characterized by
that the effective pivot axis (26) is radially adjustable in a direction opposite to the direction of the radial movement component (R) of the swashplate effective surface (19). Axial piston machine according to claim 1,
characterized by
that the effective pivot axis (26) is radially adjustable simultaneously with the swashplate pivoting. Axial piston machine according to claim 2,
characterized by
that the effective pivot axis (26) is radially adjustable by swashplate pivoting. Axial piston machine according to at least one of the preceding claims,
characterized by
that the swash plate (5) is pivotally supported on the housing (1, 7) of the axial piston machine via a pivot bearing arrangement (27, 28; 27, 28) defining the effective pivot axis (26) and the pivot bearing arrangement (27, 28; 27, 28) in one guiding arrangement (29, 29) extending in the direction of the radial movement component (R) of the swashplate active surface (19) is guided radially displaceably on the housing (1, 7). Axial piston machine according to claim 4,
characterized by
that the guide arrangement (29, 29) two mutually spaced guides (29) and the pivot bearing arrangement (27, 28; 27, 28) two in each of the guides (29) guided swivel hemispheres (27) and two mounted on this the swash plate (5) comprises half-shells (28). Axial piston machine according to at least one of the preceding claims,
characterized by
that the swash plate (5) via two pivots (34) parallel to the effective swivel axis (26) rotatably in two on opposite housing parts (8) formed, each in a plane perpendicular to the effective swivel axis (26) extending guides (33) which extend in such a way that at Swashplate swiveling of the swivel bearing arrangement (27, 28; 27, 28) impose a movement (RE) along the guide arrangement (29, 29) with the direction opposite to the direction of the radial movement component (R) of the swashplate effective surface (19). Axial piston machine according to at least one of the preceding claims,
characterized by
that the effective pivot axis (26) is arranged outside the plane of the swashplate active surface (19). Axial piston machine according to claim 7,
characterized by
that the effective pivot axis (26) intersects the drive shaft axis (3) when the swashplate is in the zero position. Axial piston machine according to at least one of claims 6 to 8,
characterized by
that the axis of rotation (37) of the pivot pin (34) intersects the drive shaft axis (3) when the swashplate is in the zero position. Axial piston machine according to at least one of claims 6 to 9,
characterized by
that the positive guides (33) run parallel to the drive shaft axis (3). Axial piston machine according to at least one of claims 6 to 8 and 10,
characterized by
that the axis of rotation (37) is arranged at the swashplate zero position to the side of the drive shaft axis (3). Axial piston machine according to at least one of claims 6 to 9 and 11,
characterized by
that the positive guides (33) at an angle (β ') obliquely to the drive shaft axis (3). Axial piston machine according to at least one of claims 6 to 12,
characterized by
that the positive guides (33) run in the direction of the effective pivot axis (26) when the swashplate is in the zero position. Axial piston machine according to claim 12 or 13,
characterized by
that the guide angle (β ') is substantially equal to the swivel angle (β) of the swash plate (5) which has been swiveled out completely. Axial piston machine according to at least one of Claims 6, 7 and 9 to 14,
characterized by
that the effective pivot axis (26) is indicated at the swashplate zero position to the side of the drive shaft axis (3). Axial piston machine according to at least one of claims 6 to 15,
characterized by
one sliding block (35) in each of the positive guides (33), in each of which one of the pivot pins (34) is mounted. Axial piston machine according to at least one of the preceding claims,
characterized by
that the pivot bearing arrangement (27, 28; 27, 28) is guided with hydrostatic support in the guide arrangement (29, 29). Axial piston machine according to claim 17,
characterized by
that the flat surfaces of the swivel hemispheres (27) for hydrostatic support in the guides (29) are designed as sliding shoe sliding surfaces. Axial piston machine according to claim 17 or 18,
characterized by
at least one through channel (40) through each swivel hemisphere (27) which connects a groove (41) formed in its flat sliding surface with a groove (41) formed in its spherical sliding surface. Axial piston machine according to claim 19,
characterized by
at least one transverse channel (42) in the swivel hemisphere (27), which connects the through channel (40) with a further groove in the spherical sliding surface of the respective swivel hemisphere (27). Axial piston machine according to at least one of claims 17 to 20,
characterized by
One lubricating oil line (43) opening into the guides (29) in the housing (1, 7) for supplying lubricating oil to the grooves (41) in the flat sliding surfaces of the swivel hemispheres (27). Axial piston machine according to at least one of claims 17 to 20,
characterized by
a longitudinal bore (44) in the adjusting device (31) for supplying lubricating oil to transverse bores (45) in the swash plate (5), each of which opens into one of the grooves (41) in the spherical sliding surfaces of the swivel hemispheres (27). Axial piston machine according to at least one of claims 17 to 20,
characterized by
that for the intermittent supply of lubricating oil from the cylinder bores (14) each have an axial bore (38) leading through the pistons (16), the ball heads (17) and the slide shoes (18) and a through bore (39) leading to the swivel hemispheres (27) are formed in the swash plate (5), which opens on the one hand in the half-shells (28) in the area of the grooves (41) and on the other hand in the swash plate active surface (19) on the slide shoe track.

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