EP2050957A1 - Axial piston machine - Google Patents

Abstract

The machine i.e. swashplate machine (1), has a cylinder drum (3) provided with cylinder bores (4) for mounting a piston (5), such that the piston is longitudinally displaced. The piston is supported by a sliding shoe (7) on a swashplate (8), where the shoe is provided in a functional connection with a retaining device (16) i.e. retaining plate (15), that rotates synchronously with the drum. The shoe is provided in the functional connection with a moment generating device (25) for generating an opposing moment on the shoe, where the opposing moment counteracts a tipping moment.

Description

The invention relates to an axial piston machine in swash plate construction, with a cylinder drum rotatably mounted about a rotation axis, wherein the cylinder drum is provided with cylinder bores, in each of which a piston is mounted longitudinally displaceable, and the pistons are supported by a respective sliding shoe on a swash plate, wherein the sliding shoes by means of a rotationally synchronous with the cylinder drum rotating retainer, in particular a retaining plate, are in operative connection.

In such axial piston machines designed as swash plate machines, the pistons are supported on the swashplate by means of a respective sliding shoe. Between the piston and the shoe, a sliding shoe joint is arranged. During operation of the swashplate machine, a tilting moment occurs on the sliding shoes due to the centrifugal forces acting on the sliding shoe, which causes the sliding shoes to tilt off the swashplate. By means of the retaining device, the sliding shoes are pressed in the direction of the swash plate to prevent lifting or tilting of the sliding shoes due to the Abkippmoments.

The retaining device can in this case be designed as a force-locking retaining device, wherein a spring device is provided, which acts on the retaining device and thus the sliding shoes in the direction of the swash plate. In order to safely avoid tilting of the sliding shoes due to the centrifugal forces occurring during operation, the spring force of the spring device is to be interpreted to the maximum speed. However, this results in high spring forces, which cause high contact forces of the sliding shoes on the swash plate and the cylinder drum on the control surface at low speeds. This results in high frictional forces, which lead to a reduced efficiency of the swash plate machine. In addition, the high contact forces lead to increased wear of the swash plate machine.

The retaining device can furthermore be designed as a form-fitting retaining device, which is fastened to the housing in the axial direction. Due to the play existing in the form-locking connection of the retaining device with the housing, the sliding shoes can tilt due to the centrifugal force occurring during operation of the swash plate, whereby a leakage current is produced, which leads to a deteriorated efficiency of the swash plate machine.

A generic, designed as a beveled disc axial piston machine is from the DE 10 2005 047 981 A1 known.

The present invention has for its object to provide a hydrostatic axial piston machine of the type mentioned available, which is improved in terms of efficiency.

This object is achieved in that the sliding blocks are operatively connected to a torque generating means by means of which a Abkippmoment counteracting counter-torque is generated on the sliding shoes. The idea according to the invention thus consists of generating on the sliding shoes by means of the torque generating device a counteracting torque which counteracts the tilting moment generated by the centrifugal forces and which partially or completely compensates for the tilting moment. As a result, the spring force and thus the contact force can be reduced in the case of a non-positive restraint device acted upon by a spring device, resulting in lower frictional forces and thus an improved efficiency of the swashplate machine. In addition, the wear of the swash plate machine is reduced by the reduced contact force. In a positive retention device, tilting of the sliding shoes is reliably avoided by the torque generating device, as a result of which a swash plate machine according to the invention has low leakage and thus high efficiency.

According to a preferred embodiment of the invention, the torque generating device is formed by rocker arms, wherein each sliding block is associated with a rocker arm, by means of which a contact force acting on the sliding shoe can be generated, which is directed opposite to the centrifugal force acting on the sliding block.

With rocker arms can be generated in a simple manner acting on the sliding shoes and the centrifugal force counteracting contact force and thus on the sliding blocks a the centrifugal force caused by the tilting moment counteracting counter-torque.

This results in particular advantages when the rocker arm is pivotally mounted on the retainer about a parallel to the axis of rotation of the retainer arranged pivot axis and can be brought into operative connection with the peripheral surface of the shoe. As a result, it is achieved with low construction costs, that counteracts the force acting on the shoes contact force of centrifugal force.

The rocker arm can in this case according to a preferred embodiment of the invention in the region of a Gleitschuhhalses of the shoe with the peripheral surface of the shoe in operative connection can be brought.

In addition, it is possible if the rocker arm according to a further embodiment of the invention in the region of a Gleitschuhplatte of the shoe is engageable with the peripheral surface of the shoe in operative connection.

Particular advantages can be achieved if the rocker arm is designed as a two-armed lever, wherein a contact surface which can be brought into contact with the sliding shoe is formed on a region of the rocker arm provided with a first lever arm and engages the center of mass of the rocker arm on a second lever arm. The rocker arm is thus actuated by the centrifugal force, whereby the contact force is proportional to the force acting on the rocker arm centrifugal force and thus proportional to the speed of the swash plate machine. With such centrifugally operated rocker arms, a counter-torque counteracting the tilting moment can be generated with little construction effort on the sliding shoes.

Particular advantages arise when the second lever arm is greater than the first lever arm, whereby at a given Kipphebelmasse a large acting on the shoe contact force can be achieved and thus with a small space having Kipphebeln a high counter-torque is generated.

According to a preferred embodiment of the invention, the mass of the rocker arm and the first lever arm and the second lever arm are designed such that the counter-torque generated by the rocker arm compensates almost or completely the tilting moment acting on the shoe.

If the rocker arm partially wraps around the sliding block and the area of the rocker arm provided with the second lever arm at least partially fills the space between two adjacent sliding blocks, a corresponding rocker arm mass can be made available without additional space requirement for the rocker arms.

The rocker arms can be arranged between the retaining device and the swash plate according to a preferred embodiment of the invention.

In addition, it is possible to arrange the rocker arms between the retaining device and the cylinder drum according to a further embodiment of the invention.

With regard to a low construction costs, there are advantages if a bearing component, in particular a cylindrical pin, is provided for supporting the rocker arm on the retaining device. By means of a respective cylinder pin, the rocker arms can be mounted pivotably on the retaining device in a simple manner.

The torque generating device formed from the rocker arms can be used in a swash plate machine with a non-positive restraint device, which is acted upon by means of a spring device in the direction of the swash plate.

In addition, the torque generating device formed from the rocker arms can be used in a swash plate machine with a positive retaining device, wherein the retaining device is supported on a housing of the axial piston machine.

Figur 1

eine Axialkolbenmaschine in Schrägscheibenbauweise des Standes der Technik in einem Längsschnitt,

Figur 2

eine kraftschlüssige Rückhalteeinrichtung des Standes der Technik,

Figur 3

eine formschlüssige Rückhalteeinrichtung des Standes der Technik,

Figur 4

eine erfindungsgemäße, als Schrägscheibenmaschine ausgebildete Axialkolbenmaschine in einem Längsschnitt,

Figur 5

einen Schnitt entlang der Linie A-A der Figur 4 mit einer Draufsicht auf die Rückhalteeinrichtung,

Figur 6

einen Ausschnitt der Figur 5 in einer vergrößerten Darstellung,

Figur 7

einen Ausschnitt der Figur 4 in einer vergrößerten Darstellung.

Further advantages and details of the invention will be explained in more detail with reference to the embodiments illustrated in the schematic figures. This shows

FIG. 1

an axial piston machine of swash plate construction of the prior art in a longitudinal section,

FIG. 2

a force-locking retaining device of the prior art,

FIG. 3

a form-locking retention device of the prior art,

FIG. 4

an inventive, formed as a swash plate machine axial piston machine in a longitudinal section,

FIG. 5

a section along the line AA the FIG. 4 with a plan view of the retaining device,

FIG. 6

a section of the FIG. 5 in an enlarged view,

FIG. 7

a section of the FIG. 4 in an enlarged view.

In the FIG. 1 is a trained as a swash plate machine 1 hydrostatic axial piston machine of the prior art shown in a longitudinal section.

The swash plate machine 1 has a cylinder drum 3 rotatably mounted about an axis of rotation 2, which is provided with a plurality of concentrically arranged cylinder bores 4, in each of which a piston 5 is mounted longitudinally displaceable. The cylinder drum 3 is in this case with a concentric with the axis of rotation 2 arranged drive shaft 6 in a rotationally fixed connection.

The pistons 5 are supported on a swash plate 8 by means of a respective sliding element 7 designed as a sliding element. The shoe 7 is in this case connected to the piston 5 by means of a spherical Gleitschuhgelenks 9 hinged. The swash plate 8 can hereby as in the FIG. 1 shown formed on a housing 10 of the swash plate machine 1, wherein the swash plate machine 1 has a fixed displacement volume. However, it is also possible that Swash plate 8 adjustably form, whereby the swash plate machine 1 has a variable displacement volume.

The cylinder drum 3 is supported in the axial direction on a housing-fixed control surface 11, which is formed on a disc-shaped control base 12. The control floor 12 is provided with kidney-shaped control slots (not shown), which form an inlet connection and an outlet connection of the swash plate machine 1.

The sliding blocks 7 are in operative connection with a retaining device 16 in the form of a disc-shaped retaining plate 15. In the in the FIG. 1 shown swash plate machine 1, the retainer 16 is designed as a non-positive retention device. The retaining plate 15 is in this case mounted on a spherical bearing component 17, which is supported on the cylinder barrel 3 by means of a spring device 18 formed by a spring or several springs. By means of the spring device 18 in this case the sliding blocks 7 are acted upon by the bearing member 17 and the retaining plate 15 in the direction of the swash plate 8.

In the FIG. 2 is a shoe 7 of the FIG. 1 shown in an enlarged view, wherein the forces occurring during operation of the swash plate machine 1 are illustrated.

During rotation of the cylinder drum 3 about the rotation axis 2 is formed at the center of gravity S of the shoe 7 attacking centrifugal force F _f , with the distance a of the center of gravity S of the shoe 7 from the center of the Gleitschuhgelenks 9 a sliding shoe 7 from the swash plate 8 abkippendes Abkippmoment generated. The tilting of the shoe 7 from the swash plate 8 is prevented by acting between the swash plate 8 and the shoe 7 and the shoe 7 and the retaining plate 15 forces F _A and F _B , by the diameter d of a circular Gleitschuhplatte 7 a, by means of the sliding shoe 7 is supported on the swash plate 8, are spaced and produce a moment counteracting the Abkippmoment. The pressing force F _A must in this case be applied by the spring plate 18 acting on the retaining plate 15.

In order to reliably avoid tilting of the sliding shoes 7 from the swash plate 8, the spring force of the spring device 18 must be designed for the high centrifugal forces F _f occurring at maximum speed. At lower speeds, these high and unnecessary pressing forces F _A lead to increased friction losses and thus a reduced efficiency of the swashplate machine 1 and to an increased wear of the swashplate machine 1.

In the FIG. 3 Here is a swash plate machine of the prior art with a positive retention device 15 in a representation according to the FIG. 2 shown.

The disc-shaped retaining plate 15 is in this case fastened by means of a fastening device 19, for example, formed by a Seegering arranged in a groove-shaped recess 20 of the housing 10 on the housing 10 in the axial direction.

The tilting moment of the sliding shoe 7 caused by the centrifugal force F _f in turn counteracts the moment formed by the forces F _A and F _B. Due to the existing manufacturing tolerances and installation reasons game of fastener 19 but the slide 7 tilts from the swash plate 8, whereby a gap 21 between the Gleitschuhplatte 7a of the shoe 7 and the swash plate 8 is formed, through which a leakage current occurs in the housing interior, the results in a deteriorated efficiency of the swash plate machine.

When in the FIG. 4 illustrated swash plate machine according to the invention are the sliding blocks 7 with a torque generating device 25 in operative connection, which generate a counteracting from the centrifugal force F _f on the sliding shoes 7 counteracting counter-torque. In this case, the torque generating device 25 is arranged between the swashplate 8 and the retaining device 16 formed by the retaining plate 15 in the region of the sliding shoe plates 7a. The retaining device 16 according to the FIG. 4 is designed as a non-positive retaining device, which according to the FIG. 1 by means of Spring device 18 and the spherical bearing member 17 is acted upon in the direction of the swash plate 8.

However, it is also possible, the retainer 15 according to the FIG. 4 form as a positive retention device, which according to the FIG. 3 is secured to the housing 3 in the axial direction.

The torque generating device 25 is - as from FIG. 5 can be seen, which shows a plan view of the retaining plate 15 and the sliding shoes 7 - of rocker arms 26, wherein each shoe 7 is associated with a rocker arm 26.

In the FIG. 6 is a part of the FIG. 5 shown in an enlarged view. The rocker arm 7 associated with a rocker arm 26 is mounted by means of a trained example as a cylindrical pin bearing member 27 about a parallel to the rotation axis D of the retaining plate 15 pivot axis 28 pivotally mounted on the outer region of the retaining plate 15.

The rocker arm 26 is in this case designed as a two-armed lever, wherein a contact surface 30 is formed on a first region of the rocker arm, which is in operative connection with the peripheral surface of the shoe 7 in the region of the shoe plate 7a. The contact surface 30 is in this case spaced from the pivot axis 28 about a first lever arm c. The second region of the rocker arm 26 opposite this region with respect to the pivot axis 28 partially wraps around the sliding shoe 7 and at least partially fills the intermediate space with the adjacent sliding shoe 7. As a result of this configuration of the rocker arm 26, the center of gravity S _{M of} the rocker arm 26 is arranged in the second region and is spaced from the pivot axis 28 by a second lever arm d. The second lever arm d is larger than the first lever arm c formed here.

During a rotation of the cylinder drum 3 about the rotation axis 2, the retaining plate 15 rotates about the rotation axis D. Here, at the center of mass S _{M of} the rocker arm 26, a centrifugal force F _s acts, which causes a torque about the pivot axis 28 with the second lever arm d is supported on the contact surface 30 by a centrifugal force F _s opposing contact force F _k , which acts on the slide shoe 7.

By choosing the lever arms c, d of the rocker arm 26 is achieved here that at a given mass of the rocker arm 26, the contact force F _{k is} greater than the force acting on the rocker arm 26 centrifugal force F _s , whereby a large contact force F _{k can be} achieved.

In the FIG. 7 is one of the FIG. 2 corresponding representation of the shoe 7 of a swash plate machine 1 according to the invention with the forces acting on the shoe 7 forces.

Like from the FIG. 7 it can be seen, the contact force F _k generated by the rocker arm 26 and acting on the peripheral surface of the shoe 7 in the region of the shoe plate 7 a directed inward, and thus the centrifugal force F _f acting on the shoe 7. The contact force F _k acting on the circumferential surface of the sliding shoe 7 in the region of the sliding shoe plate 7 a has the distance b from the center of the sliding shoe joint 9, whereby a counter-torque is generated by the contact force F _k with the distance b, which is the distance from the distance a and counteracts the centrifugal force F _f formed Abkippmoment the shoe 7.

The mass of the rocker arm 26 and the lever arms c, d of the rocker arm 26 are hereby preferably designed such that the Abkippmoment formed by the centrifugal force F _f and the distance a of the force formed by the contact force F _k and the distance b completely or almost completely is compensated, so that the sum of the moments about the midpoint of the shoe joint 9 is zero or almost zero, resulting in low forces F _A and F _B or these forces F _A , F _B disappear.

In a swash plate machine 1 according to the invention, therefore, tilting of the sliding shoes 7 by the swash plate 8 is effectively avoided by means of the torque generating device 25. By the contact force F _k generated by the rocker arms 26 and thus acting on the shoe 7, the Abkippmoment counteracting counter-torque can thus in a swash plate machine 1 according to the invention with a non-positive retainer 16, the sliding shoes 7 in the direction of the swash plate 8-pressing spring force on the retaining plate 15 acting spring device 18 can be reduced, resulting in low friction forces between the shoes 7 and the swash plate 8 result and thus a high efficiency of a swash plate machine 1 according to the invention can be achieved. In addition, a slight wear is achieved in a swash plate machine 1 according to the invention with a torque generating device 25 formed by the rocker arms 26.

In one provided with a torque generating device 25 formed by the rocker arms 26 swash plate machine 1 with a positive retention device 26 is prevented by the counterpoise generated by the rocker arms 26 tilting of the sliding shoes 7 due to the game in the fastening means of the retainer 16 in the housing 10 effectively, creating a Increase in the leakage oil is effectively avoided and the swash plate machine according to the invention has a high efficiency.

In addition, in a swash plate machine 1 according to the invention with the torque generating device 25, the centrifugal contact force between the piston 5 and the cylinder bore 4 is reduced, whereby a clamping of the piston 5 in the cylinder bore 4 can be effectively avoided.

Instead of the arrangement of the rocker arm 26 between the swash plate 8 and the retaining plate 15 in the region of the Gleitschuhplatten 7 a, it is also possible to arrange the rocker arm 26 on the cylindrical drum 3 side facing the retaining plate 15. The rocker arms 26 are thus in operative connection with the contact surface 30 with the sliding shoe neck 7b of the sliding shoe 7 arranged between the sliding shoe joint 9 and the sliding shoe plate 7a.

Claims (14)

Axial piston machine in swash plate design, with a cylinder drum rotatably mounted about an axis of rotation, wherein the cylinder drum is provided with cylinder bores, in each of which a piston is mounted longitudinally displaceable, and the pistons are supported by a respective sliding block on a swash plate, wherein the sliding shoes by means of a rotationally synchronous with the cylindrical drum rotating retainer, in particular a retaining plate, are in operative connection, characterized in that the sliding blocks (7) with a torque generating means (25) are operatively connected by means of a counteracting the Abkippmoment counter-torque on the sliding shoes (7) can be generated. Axial piston machine according to claim 1, characterized in that the torque generating means (25) of rocker arms (26) is formed, each sliding block (7) is associated with a rocker arm (26) by means of which on the sliding shoe (7) acting contact force (F _k ) is generated, which is the opposite direction of the sliding shoe (7) centrifugal force (F _f ) directed. Axial piston machine according to claim 2, characterized in that the rocker arm (26) on the retaining device (16) about a parallel to the rotational axis (D) of the retainer (16) arranged pivot axis (28) is pivotally mounted and with the peripheral surface of the sliding shoe (7) can be brought into operative connection. Axial piston machine according to claim 3, characterized in that the rocker arm (26) in the region of a Gleitschuhhalses (7b) of the sliding block (7) with the peripheral surface of the sliding block (7) can be brought into operative connection. Axial piston machine according to claim 3, characterized in that the rocker arm (26) in the region of a Gleitschuhplatte (7a) of the Gleitschuhs (7) with the peripheral surface of the sliding block (7) can be brought into operative connection. Axial piston machine according to one of claims 2 to 5, characterized in that the rocker arm (26) is designed as a two-armed lever, wherein at one with a region of the rocker arm (26) provided with a first lever arm (26) is formed with a contact surface (30) which can be brought into contact with the sliding shoe (7) and the center of mass (S _M ) of the rocker arm (26) acts on a second lever arm (d) Axial piston machine according to claim 6, characterized in that the second lever arm (d) is greater than the first lever arm (c). Axial piston machine according to claim 6 or 7, characterized in that the mass of the rocker arm (26) and the first lever arm (c) and the second lever arm (d) are designed such that the counter-torque generated by the rocker arm (26) on the sliding shoe (7) acting overturning moment almost or completely compensated. Axial piston machine according to one of claims 2 to 8, characterized in that the rocker arm (26) partially wraps around the sliding shoe (7) and the region of the rocker arm (26) provided with the second lever arm at least partially fills the space between two adjacent sliding shoes (7). Axial piston machine according to one of claims 3 to 9, characterized in that the rocker arms (26) between the retaining means (16) and the swash plate (8) are arranged. Axial piston machine according to one of claims 3 to 9, characterized in that the rocker arms (26) between the retaining means (16) and the cylinder drum (3) are arranged. Axial piston machine according to one of claims 3 to 11, characterized in that for the storage of the rocker arm (26) on the retaining means (16) has a bearing member (27), in particular a cylindrical pin is provided. Axial piston machine according to one of the preceding claims, characterized in that the retaining means (16) by means of a spring device (18) in the direction of the swash plate (8) is acted upon. Axial piston machine according to one of claims 1 to 12, characterized in that the retaining device (16) on a housing (10) of the axial piston machine is supported.

Images