DE102019120533A1 - Hydrostatic axial piston machine and process for its manufacture - Google Patents

Abstract

The invention relates to a hydrostatic axial piston machine (1) in bent axis design with a drive shaft (4) rotatably arranged about an axis of rotation (Rt) within a housing (2), with a drive flange (4) rotatably arranged about the axis of rotation (Rt) within the housing (2). 3) and with a cylinder drum (7) that is rotatable about an axis of rotation (Rz) inside the housing (2) of the axial piston machine (1), the cylinder drum (7) being provided with several piston recesses (8), in each of which a piston ( 10) is arranged to be longitudinally displaceable, the pistons (10) being articulated on the drive flange (3) and a ball-and-socket joint (20), which consists of a spherical cap-shaped receiving shell, is provided for the articulated attachment of the pistons (10) to the drive flange (3) (3a) is formed in an end face (3b) of the drive flange (3) and a ball head (10a) which is in operative connection with the piston (10). The invention also relates to a method for producing such an axial piston machine. It is proposed that, to hold down the ball head (10a) in the drive flange (3), a closed ring (13) with an annular groove (18) running around the outer diameter of the ring (13) is inserted into the receiving shell (3a) in such a way that the ring groove (18) is opposite a shell groove (16) running on the inside diameter of the receiving shell (3a) and adjoining a spherical equator (17) of the spherical head (10a), and the closed ring (13) by means of a wire (14) ), which is guided on the one hand in the annular groove (18) and on the other hand in the shell groove (16), is axially secured in the receiving shell (3a).

Description

The invention relates to a hydrostatic axial piston machine in bent axis design with a drive shaft rotatably arranged about an axis of rotation within a housing, with a drive flange rotatably arranged about an axis of rotation within the housing and with a cylinder drum arranged rotatably about an axis of rotation within the housing of the axial piston machine, the cylinder drum with a plurality of piston recesses is provided, in each of which a piston is arranged to be longitudinally displaceable, the pistons being articulated to the drive flange and for the articulated attachment of the pistons to the drive flange each a ball joint connection is provided, which consists of a spherical cap-shaped receiving shell in one end face of the drive flange and a Ball head is formed, which is in operative connection with the piston.

The invention also relates to a method for producing such a hydrostatic axial piston machine.

In hydrostatic axial piston machines of bent axis design, the pistons arranged in the cylinder drum so as to be longitudinally displaceable are usually fastened to the drive flange of a drive shaft by means of a ball joint. The piston forces are supported by the pistons on the drive flange on the drive shaft and generate a torque. In the case of axial piston machines with bent axis construction, it is necessary to fasten the piston to the drive flange in an articulated manner. For this purpose, a ball-and-socket joint is used which consists of a spherical cap-shaped receiving shell in one end of the drive flange and a ball head which is arranged on the piston and is inserted into the receiving shell of the drive flange.

During operation, the ball heads of the pistons must be locked in the respective receiving shell of the drive flange.

For this it is from the WO 2004/109107 A1 known to thread a hold-down plate with openings for the piston heads and spherical caps formed on the openings over the piston and screw it to the drive flange. Due to the required hold-down plate, which has a high manufacturing cost due to the spherical caps, and the screw connections for screwing the hold-down plate to the drive flange, such axial piston machines have a high construction cost.

In order to avoid the construction effort for the additional hold-down plate, it is already from the EP 0 567 805 B1 , the EP 1 071 884 B1 , the DE 40 24 319 A1 and the EP 0 697 520 B1 known to secure the ball heads positively in the spherical cap-shaped receiving shells. For this purpose, the spherical cap-shaped receiving shells are designed with a wrap of greater than 180 ° degrees, so that the receiving shells wrap around the spherical equator. In addition, the spherical heads are provided with a cylindrical surface, for example by flattening or processing the spherical head, so that the spherical head can be inserted into the spherical cap-shaped receiving shell in a certain position by means of the cylindrical surface and then secured in the receiving shell by tilting. This simplifies the manufacture and assembly of the components.

In the EP 0 567 805 B1 and the EP 1 071 884 B1 the cylindrical surfaces are arranged parallel to the longitudinal axis of the pistons, so that the pistons are threaded into the receiving shells parallel to the axis of rotation of the drive flange during assembly. When the pistons are tilted to the working angle, the piston heads are locked in the mounting shells. In the case of bent axis machines designed as adjusting machines, however, with such a locking of the pistons in the receiving shells, the problem can arise that the overlap of the spherical heads in the receiving shells becomes too small as the pivoting angle of the cylinder drum decreases. Therefore, such locks of the ball heads of the pistons in the drive flange are only suitable to a limited extent for adjusting machines with a variable pivot angle of the cylinder drum. These locks are not suitable for adjusting machines with a swivel angle of 0 °, since the pistons can no longer be securely held in the receiving shells and can fall out of the receiving shells.

In the DE 40 24 319 A1 and the EP 0 697 520 B1 the cylindrical surfaces are arranged obliquely to the longitudinal axis of the pistons, the angle of inclination of the cylindrical surfaces being designed such that this angle does not occur when the axial piston machine is in operation. This means that this locking device is suitable for adjusting machines and enables the pistons to be locked in the receiving shells of the drive flange even at a pivot angle of 0 °. To mount the pistons in the drive flange, the pistons have to be tilted correspondingly strongly, so that it may be necessary to provide a recess, which is complex to produce, as a clearance for the piston rod of the piston on each receiving shell. Depending on the mounting angle of the piston, this recess required for mounting the piston on the receiving shell of the drive flange can extend as far as the spherical equator, whereby the spherical cap-shaped receiving shell is correspondingly greatly reduced in area.

With those from the EP 0 567 805 B1 , the EP 1 071 884 B1 , the DE 40 24 319 A1 and the EP 0 697 520 B1 Known axial piston machines, by wrapping the spherical cap-shaped receiving shells of greater than 180 degrees, a correspondingly large thickness of the drive flange results. This leads to a corresponding installation space requirement in the axial direction of the axial piston machine, since the rotating cylinder drum with the end face containing the piston outlet openings must not strike the end face of the drive flange in which the receiving shells are arranged. In the WO 2004/109107 A1 the hold-down plate leads to an increase in the installation space in the axial direction of the axial piston machine. The space requirement for the hold-down plate or for the drive flange in the axial direction increases the dimensions of the known axial piston machine in the axial direction, which results in an increased space requirement for the installation of the axial piston machine in a vehicle.

The present invention is based on the object of providing a bent-axis axial piston machine of the type mentioned at the outset and a method for producing it, which enable the pistons to be locked in a technically simple manner in the drive flange and the axial dimensions of the axial piston machine to be reduced.

In terms of the device, this object is achieved according to the invention in that, to hold down the ball head in the drive flange, a closed ring with an annular groove running around the outer diameter of the ring is inserted into the receiving shell in such a way that the ring groove of a spherical equator running on the inner diameter of the receiving shell of the ball head adjacent shell groove is opposite, and the closed ring is axially secured in the receiving shell by means of a wire which is guided on the one hand in the ring groove and on the other hand in the shell groove.

The ball head of the piston is held down by a closed ring with a circumferential ring groove, the ring being axially secured within the receiving shell by means of a wire that is half immersed in the ring groove and the other half in the shell groove. This means that there is no need for an additional hold-down plate, which has to be screwed onto the face of the drive flange from the outside with several screws. The solution of the piston hold-down according to the invention can therefore be implemented in a compact manner with little space requirement in the axial direction and at low cost. As a result of the smaller distance between the drive flange and cylinder drum achieved in this way, the dimensions of the axial piston machine according to the invention can be reduced in the axial direction and the power density of the axial piston machine according to the invention can be increased.

The ring preferably has a radial bore into which an end region of the wire can be suspended. Thus, by simply rotating the ring in the circumferential direction, the wire can be drawn into the grooves in order to fix the ring axially.

In order to facilitate the hanging of the wire in the radial bore of the ring, the end region of the wire is advantageously angled.

In a particularly preferred embodiment of the invention, a drive flange groove is incorporated into the front face of the drive flange, via which the wire can be threaded from outside the drive flange into the ring groove of the ring and the shell groove of the receiving shell.

The drive flange groove is expediently arranged in the center of the pitch circle of the receiving shells. In this way, two adjacent receiving shells are accessible via a common drive flange groove for hooking the wire into the bore of the ring.

In order to be able to pull the wire into the two grooves by turning the ring, the ring preferably has at least two axially machined driving grooves into which a turning tool can engage, by means of which the ring can be rotated in its circumferential direction.

The shell groove advantageously adjoins the spherical equator of the spherical head on the cylinder drum side. If one imagines the axial piston machine in a view in which the axial piston machine is aligned vertically and the cylinder drum is arranged above the drive flange, the shell groove adjoins the spherical equator of the spherical head from above. Thus, the ball head is pressed down by the ring inserted into the shell groove and fixed by means of the wire, so that it cannot be pulled up out of the receiving shell by the piston movement.

The spherical equator is expediently aligned perpendicular to the axis of rotation of the drive shaft.

In order to hold the spherical body reliably in the receiving shell by means of the ring, the ring preferably has an inside which is adapted to the spherical shape of the spherical body. The inside of the ring thus forms the sphere of the ball. For this the ring can be designed on the inside according to the spherical shape of the ball head.

The invention also relates to a method for producing a hydrostatic axial piston machine of the type described.

In the method, the object is achieved in that, to hold down the ball head in the receiving shell, a closed ring with an annular groove running around the outer diameter of the ring is inserted into the receiving shell in such a way that the ring groove of a ring running on the inner diameter of the receiving shell, on a spherical equator of the spherical head adjacent shell groove is opposite, an end portion of a wire is hooked into a radial bore of the ring, and the wire is pulled by rotating the ring in the circumferential direction at the same time on the one hand in the ring groove and on the other hand in the shell groove , whereby the ring is axially secured in the receiving shell.

The wire is preferably threaded into the ring groove of the ring and the shell groove of the receiving shell from outside the drive flange via a drive flange groove machined into the drive flange.

The ring is expediently rotated in its circumferential direction by means of a turning tool which engages in at least two axially machined driving grooves.

• 1 eine Axialkolbenmaschine in Schrägachsenbauweise nach dem Stand der Technik im Längsschnitt,
• 2 eine Draufsicht auf die Stirnseite des Triebflansches der erfindungsgemäßen Axialkolbenmaschine,
• 3 einen Schnitt entlang der Linie B-B der 2,
• 4 einen Schnitt entlang der Linie A-A der 2,
• 5 eine Detailansicht des Bereichs D der 4 und
• 6 eine Detailansicht des geschlossenen Rings.

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

• 1 an axial piston machine in bent axis design according to the state of the art in longitudinal section,
• 2 a plan view of the end face of the drive flange of the axial piston machine according to the invention,
• 3 a section along the line BB of 2 ,
• 4th a section along the line AA of 2 ,
• 5 a detailed view of the area D of 4th and
• 6 a detailed view of the closed ring.

The same components are denoted by the same reference numbers in the various figures.

In 1 is a hydrostatic axial piston machine 1 Shown in bent axis construction according to the prior art in longitudinal section. The axial piston machine 1 has a housing 2 on. In the case 2 are a drive flange 3 and a drive shaft 4th arranged rotatably about an axis of rotation Rt. The drive flange 3 is in the illustrated embodiment in one piece on the drive shaft 4th formed, ie the drive shaft 4th is with the drive flange 3 Mistake.

Axially adjacent to the drive flange 3 is a cylinder drum 7th in the case 2 arranged, which are arranged rotatably about an axis of rotation Rz and with a plurality of piston recesses 8th is provided, which is concentric to the axis of rotation Rz of the cylinder drum 7th are arranged. In every piston recess 8th is a piston 10 Arranged longitudinally displaceable.

The drive shaft 4th is at the drive flange end with a torque transmission means 12 , for example a spline, designed to initiate a drive torque or to tap an output torque.

The pistons 10 are each on the drive flange 3 articulated. This is between the respective piston 10 and the drive flange 3 each a spherical joint designed as a spherical joint 20th educated. The articulation 20th is held by a ball head 10a of the piston 10 and a spherical cap-shaped and thus hollow-spherical receiving shell 3a in that of the cylinder drum 7th facing front side 3b of the drive flange 3 educated. In the cradle 3a is the piston 10 with the ball head 10a attached.

The attachment of the pistons 10 in the cradles 3a is used in the axial piston machine 1 according to the prior art by a hold-down plate 11 ensured that with multiple screws 9 with the drive flange 3 is screwed. The hold-down plate 11 and their fastening by means of the screws 9 leads to additional construction costs and increases the axial installation space of the drive flange 3 towards the cylinder drum 7th , thereby increasing the dimensions of the entire engine. This results in an increased space requirement for the integration z. B. in a mobile work machine and higher costs for the proportionally larger housing 2 .

According to the invention, these disadvantages become apparent in the case of the axial piston machine 1 through those in the 2 to 6 solution shown for fastening the piston 10 in the cradles 3a solved.

The 2 shows a plan view of that of the cylinder drum 7th facing front side 3b of the the drive shaft 4th trained drive flange 3 the axial piston machine according to the invention 1 . The receiving trays 3a are to accommodate the in the 2 ball heads not shown 10a The piston 10 out 1 intended. For fastening the piston 10 in the corresponding cradle 3a is a closed ring 13 with one on the outer diameter of the ring 13 circumferential ring groove 18th intended. The ring groove 18th is on the outside diameter of the ring 13 incorporated. In the top view of the 2 is the ring groove 18th not visible. The ring 13 is like this in the receiving tray 3a that is inserted on the outside diameter of the ring 13 arranged ring groove 18th one on the inside diameter of the receiving tray 3a arranged on a spherical equator 17th of the ball head 10a adjacent, in the plan view of 2 also not visible, shell groove 16 opposite is. For axial fixation of the closed ring 13 in the cradle 3a is a wire 14th provided, the one in the end face 3b of the drive flange 3 in the drive flange 3 incorporated drive flange groove 15th threaded and in one, in the plan view of 2 invisible radial bore 19th of the ring 13 is hung. The radial bore 19th is in the area of the ring groove 18th arranged. The one at the front 3b of the drive flange 3 incorporated drive flange groove 15th is centered on the pitch circle of the receiving trays 3a arranged. By turning the ring 13 in the circumferential direction is the one on the ring 13 hooked wire 14th at the same time in the ring groove 18th on the ring 13 and the shell groove 16 on the receiving tray 3a pulled so that the wire 14th halfway into the ring groove 18th of the ring 13 and the other half in the shell groove 16 the receiving tray 3a immersed. This is how the ring becomes 13 in the cradle 3a by means of the in the two grooves 16 , 18th drawn in wire 14th axially secured.

The 3 shows a section along the line BB of FIG 2 . This sectional view shows how the wire 14th in the, in the drive flange 3 incorporated drive flange groove 15th is threaded.

The 4th shows a corresponding section along the line AA of FIG 2 . The ring 13 is like this in the receiving tray 3a inserted that the ring groove 18th on the outer circumference of the ring 13 is incorporated, which is on the inside diameter of the receiving shell 3a running to the spherical equator 17th of the ball head 10a adjacent shell groove 16 opposite is. The ring groove 18th on the ring 13 and the shell groove 16 on the receiving tray 18th thus together form an annular channel between the ring 13 and the receiving tray 3a into which the wire 14th can be withdrawn. The shell groove 16 is here on the inside diameter of one on the receiving shell 3a trained lowering 21st incorporated into the ring 13 is arranged and can be used. The wire 14th is about the in the front side 3b of the drive flange 3 incorporated drive flange groove 15th threaded. The end of the wire 14th is angled and into the radial hole 19th of the ring 13 hung. This is the area around the drive flange groove 15th marked with the number D.

In the 5 FIG. 3 is a detailed view of area D of FIG 4th shown with the same reference numerals in an enlarged illustration. From the 5 it can be seen that the inside of the ring 13 the sphere of the ball of the ball head 10a of the piston 10 replicates the one in the cradle 3a is articulated.

The 6 shows a detailed view of the ring 13 with the ring groove running around the outer circumference 18th and the radial bore 19th for hanging the wire 14th . To put the wire in the ring groove 18th and the shell groove 16 to be able to pull, indicates the ring 13 at least two axially incorporated driving grooves 20th on, in which a turning tool can engage, by means of which the ring 13 can be rotated in its circumferential direction to that in the bore 19th hooked wire 14th in the two grooves 16 , 18th to move in.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2004/109107 A1 [0005, 0009]
• EP 0567805 B1 [0006, 0007, 0009]
• EP 1071884 B1 [0006, 0007, 0009]
• DE 4024319 A1 [0006, 0008, 0009]
• EP 0697520 B1 [0006, 0008, 0009]

Claims (12)

Hydrostatic axial piston machine (1) of bent axis design with a drive shaft (4) rotatably arranged about an axis of rotation (Rt) within a housing (2), with a drive flange (3) rotatable about the axis of rotation (Rt) within the housing (2) and with a cylinder drum (7) rotatably around an axis of rotation (Rz) within the housing (2) of the axial piston machine (1), the cylinder drum (7) being provided with several piston recesses (8) in each of which a piston (10) is arranged longitudinally displaceable is, wherein the pistons (10) are articulated to the drive flange (3) and for the articulated attachment of the pistons (10) to the drive flange (3) a ball joint connection (20) is provided, which consists of a spherical cap-shaped receiving shell (3a) in an end face (3b) of the drive flange (3) and a ball head (10a) which is in operative connection with the piston (10), characterized in that for holding down the ball Elkopfes (10a) in the drive flange (3) a closed ring (13) with a ring groove (18) running around the outer diameter of the ring (13) is inserted into the receiving shell (3a) in such a way that the ring groove (18) is a on the inside diameter of the receiving shell (3a) extending to a spherical equator (17) of the spherical head (10a) is opposite the shell groove (16), and the closed ring (13) by means of a wire (14), which on the one hand in the ring Groove (18) and on the other hand in the shell groove (16) is guided, is axially secured in the receiving shell (3a). Hydrostatic axial piston machine (1) according to Claim 1 , characterized in that the ring (13) has a radial bore (19) into which an end region of the wire (14) can be suspended. Hydrostatic axial piston machine (1) according to Claim 2 , characterized in that the end region of the wire (14) is angled. Hydrostatic axial piston machine (1) according to one of the Claims 1 to 3 , characterized in that a drive flange groove (15) is incorporated into the end face of the drive flange (3), via which the wire (14) from outside the drive flange (3) into the ring groove (18) of the ring (13) and the Shell groove (16) of the receiving shell (3a) can be threaded. Hydrostatic axial piston machine (1) according to Claim 4 , characterized in that the drive flange groove (15) is arranged in the middle of the pitch circle of the receiving shells (3a). Hydrostatic axial piston machine (1) according to one of the Claims 1 to 5 , characterized in that the ring (13) has at least two axially machined driving grooves (20) into which a turning tool can engage, by means of which the ring (13) can be rotated in its circumferential direction, so that the wire (14) in the ring groove (18) and the shell groove (16) can be pulled. Hydrostatic axial piston machine (1) according to one of the Claims 1 to 6 , characterized in that the shell groove (16) adjoins the spherical equator (17) of the spherical head (10a) on the cylinder drum side. Hydrostatic axial piston machine (1) according to one of the Claims 1 to 7th , characterized in that the spherical equator (17) is oriented perpendicular to the axis of rotation (Rt). Hydrostatic axial piston machine (1) according to one of the Claims 1 to 8th , characterized in that the ring (13) has an inside which is adapted to the spherical shape of the spherical head (10a). Method for manufacturing a hydrostatic axial piston machine (1) with a drive shaft (4) rotatably arranged about an axis of rotation (Rt) within a housing (2), with a drive flange (3) rotatably arranged about the axis of rotation (Rt) within the housing (2) and with a cylinder drum (7) rotatably about an axis of rotation (Rz) within the housing (2) of the axial piston machine (1), the cylinder drum (7) being provided with several piston recesses (8) in each of which a piston (10) is arranged to be longitudinally displaceable, the pistons (10) being articulated to the drive flange (3) and a ball-and-socket joint (20), which consists of a spherical cap-shaped receiving shell (3a ) is formed in an end face (3b) of the drive flange (3) and a ball head (10a) which is in operative connection with the piston (10), characterized in that for holding down g of the ball head (10a) in the receiving shell (3a), a closed ring (13) with an annular groove (18) running around the outer diameter of the ring (13) is inserted into the receiving shell (3a) in such a way that the ring groove ( 18) is opposite a shell groove (16) running on the inside diameter of the receiving shell (3a) and adjoining a spherical equator (17) of the spherical head (10a), an end region of a wire (14) into a radial bore (19) of the ring ( 13) is hooked in, and the wire (14) by rotating the ring (13) in the circumferential direction is pulled simultaneously on the one hand into the ring groove (18) and on the other hand into the shell groove (16), whereby the ring (13) in the receiving shell (3a) is axially secured. Procedure according to Claim 10 , characterized in that the wire (14) via a drive flange groove (15) worked into the drive flange (3) from outside the drive flange (3) into the ring groove (18) of the ring (13) and the shell groove (16) of the receiving shell (3a) is threaded. Procedure according to Claim 10 or 11 , characterized in that the ring (13) is rotated in its circumferential direction by means of a turning tool which engages in at least two axially machined driving grooves (20).

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