WO2012150069A1 - Axial piston machine having an inclined-axis construction - Google Patents

Abstract

The invention relates to an axial piston machine (1) with an inclined-axis construction, comprising a plurality of piston elements (3) that can be guided in a rotatable cylinder arrangement (2) such that they move longitudinally, and a region (4) which transmits torque and is functionally connected to said piston elements (3). The torque-transmitting region (4) is designed to pivot about a pivot axis (10), and a displacement volume of the axial piston machine (1) varies as a function of the pivoting movement of the torque-transmitting region (4).

Description

 Axial piston machine in Schräqachsenbauweise

The invention relates to an axial piston machine in a bent-axis design according to the closer defined in the preamble of claim 1. Art.

In practice, axial piston machines are used to drive a variety of hydraulically actuated devices and the conversion of torque. Among other things, this results from the high power density of axial piston machines and the possibility of infinitely variable adjustment of the displacement.

Axial piston machines are provided, for example, as hydraulic drives for hydraulically operated machines, such as excavator arms and excavator buckets, loaders of wheel loaders, telehandlers, bulldozers, load dumpers of dump trucks and the like. Moreover, it is also known to integrate axial piston machines in travel drives such machines, the axial piston machines represent parts of hydrostatic transmission of single-wheel drives or power-split continuously variable transmissions.

In this case, adjustable axial piston machines are preferably used in swash plate or Schrägachsenbauweise, where designed as swash plate axial piston machines are usually realized by design with a maximum adjustment angle of +/- 21 degrees. Due to the design-related limited Verstellwinkelbereiches swash plate machines are characterized by a low power density and therefore relatively large perform in order to provide a corresponding performance or to convert to the desired extent.

Furthermore, swash plate machines also have low efficiencies, since piston elements slide on a swash plate by means of sliding blocks and the piston elements are thereby subjected to transverse forces. The transverse forces acting on the piston elements result in the connection area between the piston elements and the piston elements. elements respectively associated cylinders during operation occurring frictional forces that adversely affect the efficiency. In addition, leakage currents which adversely affect the volumetric efficiency of a swashplate machine arise in the region of gaps between the piston elements and the respective associated cylinders.

Axial piston machines in Schrägachsenbauart are compared to swash plate machines with higher efficiencies operable, with conventionally executed Schrägachseneinheiten a maximum adjustment angle is about 25 degrees. However, such bent axis units are usually not durchschwenkbar.

If bent axis units are operated as pumps, they are usually used in open circuits. In order to be able to display a changing oil delivery direction in the area of a bent axis unit, the direction of rotation of a bent axis unit must be changed. Axial piston pumps are in Schrägachsenbauart without a torque leading portion and a cylinder connecting synchronous joint executed by piston elements disadvantageously transverse forces between the cylinder device and the torque leading area to be transmitted to support occurring between the cylinder device and a valve plate frictional forces can. Piston ends of the piston elements are usually trapped in calottes and transmit there the piston force in an axial force and in a circumferential force.

Although the efficiencies of such bent axis units are higher than the efficiencies of the above-described swash plate units, a power density of bent axis units is still below a desired range due to the constructional circumstances briefly explained below.

Known bent-axis units, in particular inclined-axis pumps, are usually designed with a fixed drive shaft axis and pivotably designed cylinder device. An oil guide between one standing housing and the pivotally running cylinder device is usually done via a sliding carriage. In order to ensure the oil supply with the lowest possible leakage volume flows, an appropriate seal must be provided. However, the seal limits a maximum pivot angle of the cylinder device, of which a maximum displacement and thus a power density of a bent axis unit is dependent, such that a power density is low.

From DE 10 2007 033 008 A1 an axial piston machine is in

Schrägachsenbauart known whose Gesamtschwenkwinkelbereich is 90 degrees, with a cylinder device out of a zero position in which a displacement of the axial piston machine is equal to zero, each to

+/- 45 degrees is designed pivoting. The cylinder device is mounted in a pivotable yoke housing. The cylinder to be supplied and flowing out of the cylinder device oil is respectively removed in the region of a Jochlagerung in a complex manner a housing side trained hydraulic system or supplied to this. In this case, the respectively funded by piston elements in the cylinder device or sucked oil between the cylinder device or between the cylinder device and the piston elements each limited piston chambers and a yoke bearing over relatively long oil channels to lead, however, cause undesirable high pressure losses and thus deteriorate efficiency.

In addition, in the region of the interface between the pivoting yoke and a stationary bearing bracket, i. H. in the region of the yoke bearing device, to provide a seal designed for high operating pressures, which permits a pivoting movement of the yoke housing and also of the cylinder device or the cylinder drum relative to a torque-carrying region or a drive flange of the axial piston machine.

Although such bent axis units have better efficiencies than the oblique axes executed with a pivoting angle of approximately 25 degrees. However, the production costs are higher than that of the efficiency-degraded bent axis machines.

The present invention is therefore based on the object to provide a cost-manufacturable axial piston machine in oblique axis design available, which is operable with high efficiency and is characterized by a high power density.

According to the invention this object is achieved with an axial piston machine with the features of claim 1.

The axial piston machine according to the invention in a bent-axis design is designed with a plurality of longitudinally movably guided piston elements in a rotatable cylinder device and with a region operatively connected to the piston elements and carrying a torque.

According to the invention, the torque carrying area is one

Swivel axis pivotally mounted and a displacement of the axial piston varies depending on the pivotal movement of the torque-conducting area, which an efficiency of the axial piston impairing oil ducts and manufacturing costs increasing sealing measures in the axial piston according to the invention are not provided. This results from the fact that incoming and outflowing oil is interchangeable between the cylinder device and a fixed housing without the interposition of long and large pressure losses generating oil channels and not over the stationary housing rotatably running component components, in the area then costly and costly Abdichtmaßnahmen are provided , is to be exchanged.

In addition, a swivel angle range of the axial piston machine according to the invention is limited by the unnecessary complicated seal to a lesser extent, thus the axial piston machine according to the invention can be executed with a higher power density than known axial piston machines.

In a structurally simple and space-saving and cost-effective embodiment of the axial piston machine according to the invention, the torque-guiding region is a bevel gear which can be brought into engagement with a further bevel gear.

A likewise structurally simple and cost-effective embodiment of the axial piston machine according to the invention is characterized in that the torque-guiding region is rotatably supported by a bearing pivotable about the pivot axis via a bearing axially and radially bearing means in the region preferably a pivoting movement generating device to initiate a pivoting force can.

In further space-saving embodiments of the axial piston according to the invention, the pivot axis of the torque leading portion is arranged perpendicular to a rotation axis of the cylinder device and / or an axis of rotation of the torque leading portion at a displacement of the axial piston machine equal to zero in coincidence with the axis of rotation of the cylinder device.

If the cylinder device is rotatably mounted in a housing via a bearing axial and radial forces bearing means, the axial piston machine according to the invention with a low-efficiency forced lubrication executable over which only limited areas are to be supplied with lubricating and cooling fluid. Thus, the axial piston according to the invention in comparison to known axial piston machines, in which rotating components are arranged completely in an oil bath, in a structurally simple manner with a higher efficiency operable.

Housing-side hydraulic channels are in another operable with little control and regulation effort embodiment of Axialkolbenma- machine depending on the rotational movement of the cylinder device in each case engageable by the piston elements and the cylinder means limited piston chambers in operative connection.

If the torque-guiding region is connected to the piston elements via piston shoes and the piston elements are pivotably mounted in the piston shoes, the axial piston machine according to the invention can be embodied with a swivel angle range enabling a high power density.

If the torque-guiding region and the cylinder device for speed synchronization via a shaft-like element operatively connected to each other, the piston elements during operation of the axial piston according to the invention are substantially free of transverse forces, whereby a high sealing effect in the region between the piston elements and the cylinder device can be ensured at the same time little effort ,

If the cylinder device with a side facing away from the torque region abuts against a valve plate fixed on the housing side, in the region of which the hydraulic channels each open into preferably kidney-shaped regions, the axial piston machine according to the invention can be operated with high efficiency since the cylinder device is connected between the valve plate and the cylinder device In the operation of the axial piston machine adjusting thin oil film with low frictional forces relative to the valve plate is rotatable.

Both the features specified in the patent claims and the features specified in the following exemplary embodiments of the axial piston machine according to the invention are in each case suitable alone or in any combination with each other to further develop the object according to the invention. The respective feature combinations represent no limitation with respect to the development of the subject matter according to the invention, but essentially have only an exemplary character. Further advantages and advantageous embodiments of the axial piston according to the invention will become apparent from the claims and the embodiment described in principle below with reference to the drawings.

It shows:

1 is a highly schematic representation of an embodiment of the axial piston machine according to the invention in a bent-axis design in a first operating state. and

Fig. 2 is a representation corresponding to Fig. 1 of the axial piston machine in a second pivoted operating state of a torque conducting area.

1 shows a functional diagram of an embodiment of an adjustable axial piston machine 1 in a bent-axis design. The axial piston machine 1 is designed with a plurality of piston elements 3 which are guided longitudinally movably in a rotatable cylinder device 2 and with a region 4 which is operatively connected to the piston elements 3 and carries a torque. The piston elements 3 are sealed in the cylinder device 2 by means of suitable seals. The axial piston machine 1 is presently designed as axial piston pump in a bent-axis design, which is to operate in a closed circuit. The cylinder device 2 is rotatably mounted about a rotation axis 5 in a housing 6, wherein the cylinder device 2 is rotatably mounted in the housing 6 via a bearing axial and radial forces bearing means 7. The axial forces of the cylinder device 2 are transmitted to the housing 6. The bearing device 7 is arranged radially between between the piston elements 3 and the cylinder device 2 limited piston chambers 8 in a favorable manner.

In the present case, the torque-guiding region 4 is designed as a bevel wheel which meshes with a further bevel gear 9 and is provided with a pivoting gear. Axle 10 from the zero position shown in Fig. 1 in a first in Fig. 2, which is the axial piston machine 1 from a in Fig. 1 by the arrow II marked in more detail view, shown pivoting position is pivotable. In the zero position of the ring gear 4 is a stroke of the piston elements 3 in the cylinder device 2 and a displacement of the axial piston machine 1 is substantially equal to zero. A swivel angle between the axis of rotation 5 of the cylinder device 2 and a rotation axis 1 1 of the torque-conducting region 4 corresponds in the operating state of the axial piston machine 1 illustrated in FIG. 2 substantially to approximately + 45 degrees.

In addition, the torque leading area is 4 around the

Swivel axis 10 from the zero position shown in Fig. 1 in a second pivot position, not shown in the drawing by a pivot angle of -45 degrees pivot.

Furthermore, the torque-guiding region or the bevel gear 4 is rotatably supported by a bearing device 12 accommodating axial and radial forces in a cage 13 pivotable about the pivot axis 10, the bearing device 12 in the present case comprising a tapered roller bearing 14 and a cylindrical roller bearing 15.

In the illustrated in detail in Fig. 1 zero position of the torque leading portion 4 and the cage 13, the axis of rotation 5 of the cylinder device 2 and the axis of rotation 1 1 of the torque leading portion 4 are in line or run in the same direction. When rotating ring gear 4 and associated piston shoes 16, in the area of which the piston elements 3 are connected to the ring gear 4 and pivotally mounted, the cylinder device 2 is taken over a shaft-like element 17 and a synchronous steering, via the torque leading portion 4 and the Cylinder device 2 are operatively connected to each other for speed synchronization.

The wave-like element 17 and the synchronous steering, the speed synchronization between the ring gear 4 with the piston shoes 16 and the cylinder device 2 is provided, helps in the region between the housing side fixed valve plate 18 and the cylinder device 2 to support occurring frictional forces and to move the piston elements 3 in the cylinder device 2 substantially free of lateral forces. This means that over the shaft-like element 17 in the present case only a friction force acting between the cylinder device 2 and a housing-side fixed valve plate 18 during operation of the axial piston machine 1 is overcome, at which the cylinder device 2 with a side 19 facing away from the torque side 19 on the housing side fixed valve plate 18 rests in the region of the housing-side hydraulic channels 20 open in kidney-shaped areas 21.

The valve plate 18 is non-rotatably operatively connected to the housing 6.

In the present case, the valve plate 18 is provided as a sliding and sealing surface, wherein the oil flow between the housing 6 and the cylinder device 2 takes place via the two valve plate-side regions 21 and the hydraulic channels 20, which are kidney-shaped at least in regions. In the present case executed housing 6, the hydraulic channels 26 and 27 with respect to a low pressure loss optimally executed. The valve-plate-side hydraulic channels 20 are alternately in operative connection with the piston chambers 8 bounded by the piston elements 3 and the cylinder device 2 as a function of the rotational movement of the cylinder device 2, for example, to supply hydraulic pressure to a desired extent to a hydraulically actuated excavator arm.

If the ring gear 4 is pivoted about the pivot axis 2 starting from the zero position shown in FIG. 1 in the direction of the first maximum pivot position shown in FIG. 2, a stroke of the piston elements 3 in the cylinder device 2 increases up to a maximum stroke value is equivalent to a maximum displacement of the axial piston machine 1. In the swung-out position of the cage 13 and also of the plate wheel 4 shown in FIG. 2, the axis of rotation 5 of the cylinder device 2 and close the axis of rotation 12 of the torque leading portion 4 and the ring gear an angle of 45 degrees. When rotating the ring gear 4 and the associated piston shoes 16, the cylinder drum 2 is taken by the shaft-like element 17 and the piston elements 3 perform on the rotational movement of their maximum stroke.

The pivot axis 10 of the ring gear 4 and also of the cage 13 is perpendicular to the axis of rotation 5 of the cylinder device 2. In the illustration according to FIG. 1, the pivot axis 10 of the ring gear 4 simultaneously corresponds to a rotation axis of the further plate wheel 9 or a shaft 22 rotatably connected thereto, which is connected to a non-illustrated mechanical transmission via a spur gear 23 and which in the present case is rotatably mounted in a main housing 24 via a likewise axial and radial forces receiving bearing means 25.

This means that in the pump operation of the axial piston machine 1 via the shaft 22 mechanical power or torque is performed on the ring gear 4 and in a motor operation of the axial piston engine via the shaft 22 mechanical power is removed.

Characterized in that the cage 13 is designed pivotable about the pivot axis 10 and the axis of rotation of the shaft 22, with the other ring gear 9 is rotatably connected, the pivot axis 10 corresponds to the drive of the plate wheel 4 by the further ring gear 9 without affecting the power transmission over the teeth of the ring gear 4 and the other ring gear 9 even during pivoting of the cage 13 feasible.

Depending on the particular application, it is also possible, instead of the spur gear 23, to provide another suitable shaft connection, such as a flange connection or the like, in order to introduce a torque applied to the plate rim 4 into the mechanical gear or to transfer it from the mechanical gear to the ring gear 4 , The circumferential force in the tooth engagement of the two bevel gears 4 and 9 is supported by the adjusting device of the cage 13. In addition to this circumferential force, the adjusting device must also support the not 100% balanced piston forces.

Reference to axial piston machine

cylinder device

piston element

Torque leading range, bevel gear

Rotary axis of the cylinder device

casing

Storage facility

piston chamber

another bevel gear

Pivot axis of the torque-guiding area. Rotary axis of the torque-carrying area. Bearing device of the torque-bearing area. Cage

Tapered roller bearings

Cylindrical roller bearings

piston shoe

wave-like element, synchronous joint

valve plate

Side of the cylinder device

hydraulic channel

kidney-shaped area

wave

spur gear

main body

Storage facility

kidney-shaped area on the housing side

Hydraulic channel on the housing side

Claims

claims 1 . Axial piston machine (1) in a bent-axis design with a plurality of piston elements (3) guided longitudinally movably in a rotatable cylinder device (2) and with a region (4) operatively connected to the piston elements (3), characterized in that the torque-guiding region (4) is designed to pivot about a pivot axis (10) and a displacement volume of the axial piston machine (1) in dependence on the pivoting movement of the torque leading portion (4) varies. 2. Axial piston machine according to claim 1, characterized in that the torque-guiding region (4) is a bevel gear which can be brought into engagement with a further bevel gear (9). 3. Axial piston machine according to claim 1 or 2, characterized in that the torque-guiding region (4) via a axial and radial forces receiving bearing device (12) in a about the pivot axis (10) pivotally mounted cage (13) is rotatably mounted. 4. Axial piston machine according to one of claims 1 to 3, characterized in that the pivot axis (10) of the torque-guiding region (4) perpendicular to a rotation axis (5) of the cylinder device (2) is arranged. 5. axial piston machine according to claim 4, characterized in that an axis of rotation (1 1) of the torque leading portion (4) at a displacement of the axial piston machine (1) equal to zero in coincidence with the axis of rotation (5) of the cylinder device (2). 6. Axial piston machine according to one of claims 1 to 5, characterized in that the cylinder device (2) is rotatably mounted in a housing (6) via an axial and radial forces receiving bearing means (7), wherein the axial forces of the cylinder device (2) are received by the housing (6). 7. Axial piston machine according to one of claims 1 to 6, characterized in that the valve plate side channels (20) in dependence of the rotational movement of the cylinder device (2) each of the piston elements (3) and the cylinder device (2) limited piston chambers (8) in operative connection can be brought. 8. Axial piston machine according to one of claims 1 to 7, characterized in that the torque-guiding region (4) via piston shoes (16) with the piston elements (3) is connected, wherein the piston elements (3) in the piston shoes (16) pivotally mounted are. 9. axial piston machine according to one of claims 1 to 8, characterized in that the torque leading portion (4) and the cylinder device (2) for speed synchronization via a shaft-like element (17) are operatively connected to each other in an articulated manner. 10. Axial piston machine according to one of claims 7 to 9, characterized in that the cylinder device (2) with a torque leading portion (4) facing away from a housing side fixed valve plate (18) is applied, in the region of the hydraulic channels (20) respectively in preferably kidney-shaped areas (21) open.