CH716080A1 - Axial piston machine. - Google Patents

Abstract

Axial piston machine comprising a drive shaft, a drive unit connected to it in a rotationally fixed manner with one or more drive unit pistons, the piston stroke of which can be adjusted by a swash plate, at least one return spring acting on the swash plate and an actuating piston being supported on the swash plate, the axial piston machine at least one control or regulating valve (30) or at least one control or regulating unit, characterized in that an actuating piston (22) is guided in the connection plate and an actuating lever (21) acts as a coupling element between the actuating piston and the swashplate and the actuating piston axis and the actuating lever axis are mutually exclusive are located on a half-plane H1 emanating from the drive shaft axis.

Description

The invention relates to an axial piston machine in swash plate design with at least one control or regulating valve for adjusting the angle of inclination of the swash plate.

[0002] The term axial piston machine includes both an axial piston pump and an axial piston motor. A special type of axial piston machine is the swash plate machine, which comprises an engine in the form of an engine drum in which several engine pistons are axially displaceably mounted in corresponding cylinder bores of the engine. The drive unit is non-rotatably connected to the drive shaft of the axial piston machine, which is set in rotation by mechanical work, for example in the pump mode. In pump operation, from a certain starting position, the pistons perform a stroke movement parallel to the axis of rotation during half a revolution, in order to suck in hydraulic fluid from the low-pressure side, referred to in the following text as hydraulic oil for better readability, whereas the remaining half revolution of a full rotation around the axis of rotation is a lowering movement execute and thereby have brought the hydraulic oil previously sucked in to the high pressure level and the work output, ie to the high pressure side. In the motor operating mode, the operating principle is reversed in that a controlled pressure actuation of the engine piston generates a rotational movement of the drive unit. The stroke of the engine pistons is determined by the swivel angle of the swash plate, also known as the swivel cradle. When the drive shaft rotates, the engine pistons performing the lifting movement are constantly aligned parallel to the latter and are each pulled or pushed against the movement specified by the swash plate and the retraction plate with the aid of a sliding shoe that is hinged to the piston. The swash plate does not follow the rotary movement of the drive shaft, so that the sliding shoes attached to the piston perform a sliding movement on the surface of the swash plate facing the sliding shoes. The stroke of the engine pistons used can thus be adjusted via the swivel angle of the swashplate. The maximum stroke of the engine piston results from the maximum possible swivel angle of the swash plate. The minimum stroke of the engine piston results from the minimum possible swivel angle of the swash plate.

There are also axial piston machines in which the so-called swiveling of the swash plate over the neutral position, the so-called mooring operation, is provided. There are also axial piston machines that can work in four-quadrant operation. At this point it should be pointed out that the invention can also be applied to such axial piston machines.

[0004] The desired / required value of the swivel angle of the swash plate, which is determined by the control or by a regulation, is achieved by means of a mechanical power transmission through the actuating unit acting on the swash plate. The force develops through an oil pressure, the so-called control pressure, which acts on the control piston belonging to the control unit. The pressure level of the set pressure is specified via a control valve hydraulically connected upstream of the setting unit or a hydraulic regulating valve connected hydraulically upstream of the setting unit. There is an oil connection between the control pressure output, which is also referred to as the working connection, of the control valve and the so-called control chamber. In the actuating chamber, the actuating piston is acted upon by the hydraulic oil that is under actuating pressure.

Furthermore, in addition to the control valve, further purely hydraulic or mechatronic components can be provided which are used to control or regulate the axial piston machine. An example of a purely hydraulic component is a pressure cut-off which can be used, for example, to limit the output pressure of an axial piston machine operating in pump mode. An example of a mechatronic component is an electrically controllable pressure reduction unit. The output pressure of such a pressure reduction unit can, for example, be fed to the valve piston of the control valve which specifies the control pressure and which has a control pressure connection and a corresponding control surface provided for this purpose.

Since there is a desire here for the most compact possible design, the object of the present invention is to be seen in showing a suitable solution for the arrangement and integration of corresponding hydraulic components in or on the axial piston machine.

This object is achieved by an axial piston machine according to the features of claim 1. Advantageous embodiments of the axial piston machine are the subject of the dependent claims.

Starting from the generic axial piston machine, it can be advantageous for certain types of control or regulation if the control or regulating valve which specifies the set pressure is located within the connection plate of the axial piston machine.

It when the control and / or regulating valve can be inserted from the outside into the connection plate, for example. Can be screwed into a corresponding bore in the connection plate from the outside, is particularly advantageous. For this purpose, the relevant control or regulating valve is preferably provided with a cartridge-shaped housing. This allows a simple change. Different types of valves or controllers can be used without any problems, depending on the application. The corresponding control or regulating valve is already integrated in the axial piston machine. However, an exchange is possible without opening the axial piston machine and the axial piston machine remains identical. For example, a structure for volume flow control of the axial piston machine can be represented by appropriate installation of a volume flow control valve, or a structure for power control of the axial piston machine can be represented by appropriate installation of a power regulator.

The invention further provides that one or more other hydraulic components, in particular valves or regulators, for controlling the control or regulating valve and / or for controlling or regulating the axial piston machine are stacked on a section of the connecting plate surface area, in particular on a section the connecting plate in the area of the control or regulating valve housed there. This enables very short connection paths for the hydraulic connection of the individual hydraulic components. Furthermore, the axial piston machine can be equipped with the desired hydraulic components quickly and easily. The proposed construction also allows the construction of a particularly compact unit that can be integrated into a higher-level machine in a space-saving manner.

A particular advantage of the axial piston machine arises when, according to a preferred embodiment of the invention, at least one controller axis of the stacked hydraulic components is perpendicular to the engine axis of the axial piston machine. Ideally, all controller axes of the stacked hydraulic components are perpendicular to the engine axis.

The control or regulating valve preferably acts hydraulically on a mechanical adjustment unit, this mechanically triggers a pivoting of the swash plate as a function of the control pressure of the control valve. For this purpose, the adjusting device preferably comprises an adjusting lever which is mechanically connected to the swash plate on the one hand and is pressurized by the generated adjusting pressure of the control valve on the other hand via an adjusting piston attached at the end. A parallel course of the longitudinal axes of the adjusting lever and / or adjusting piston and / or control piston of the control or regulating valve is advantageous here. It is particularly advantageous if the central longitudinal sections of the adjusting lever, the adjusting piston and the control or regulating valve and the engine itself lie in a common plane. The same can optionally also apply to the return spring of the swash plate and other components of the axial piston machine.

The hydraulic pilot control of the control or regulating valve for setting the desired angle of inclination of the swash plate and thus the conveyable volume in pump operation or the power in motor operation is carried out according to a possible embodiment of the invention by means of a pressure reduction unit whose pressure output with the control input of the control valve in Connection. It is possible for the pressure reduction unit to be electromagnetically piloted in order to be able to set the outgoing control pressure that is applied to the control valve accordingly. The pressure reduction unit is mounted on the intended mounting section on the connecting plate surface, possibly stacked there with additional hydraulic components.

Further hydraulic components for controlling / regulating the axial piston machine can also be placed on the outer surface of the connection plate, for example placed in a sandwich-like manner on the aforementioned pressure reduction unit. It applies here that at least one controller axis of the stacked hydraulic components, ideally all controller axes, run parallel to one another and are oriented perpendicular to the longitudinal axis of the drive shaft.

[0015] One or more valves for implementing control types are understood as further hydraulic components. In particular, such valves for pressure control, volume control, power control or a combination thereof. Mechanical-hydraulic controllers or electric-hydraulic controllers are conceivable. A specific example of these additional hydraulic components is, for example, a pressure cut-off, in particular in combination with a load-sensing stage. The load-sensing stage with pressure cut-off can be accommodated compactly within a twin housing that sits on the housing of the pressure reduction unit.

In the chosen structure, it is advantageous if the longitudinal axes of the pressure reduction unit on the one hand and load sensing and pressure separation on the other hand run parallel to one another, but do not lie in the same vertical sectional plane. Specifically, the central longitudinal axis of the pressure reduction unit is offset from the common central longitudinal sectional plane of the load sensing stage and pressure cut-off.

In a further advantageous embodiment of the invention, the axial piston machine is designed as a modular kit with at least two connection plates. The at least two available connection plates allow an uncomplicated and quick adaptation of the axial piston machine to the desired type of application. In particular, the connection plate can also be exchanged by the customer without specialist knowledge.

A decisive advantage of such a kit is that, for example, at least one connection plate is kept ready for each direction of rotation of the drive shaft. By changing the connection plate, the axial piston machine can be quickly and flexibly converted to the desired direction of rotation in pump and / or motor operation. In the ideal case, the at least two connection plates only differ in the position of the hydraulic connections, i.e. the positioning of the high or low pressure connection (suction connection in pump operation), these are only arranged in a reversed position for the respective direction of rotation. Usually, the low-pressure and high-pressure connections on axial piston machines differ in terms of diameter.

The advantageous modular concept allows additional variations of the connection plate, so the high and low pressure connection can be in a connection plate at the rear end of the axial piston machine in the axial direction, while another connection plate has laterally positioned pressure connections. Likewise, the available connection plates can be equipped with or without a shaft drive for connecting a downstream machine, in particular an axial piston machine. If the connection plate includes a corresponding through drive, a detachable arrangement of a flange adapter is useful in order to enable flexible connection of different flange types.

Further advantages and properties of the invention are to be explained in more detail below with reference to an exemplary embodiment shown in the figures. Show it: <tb> <SEP> Figure 1: a longitudinal section along the drive shaft through the axial piston machine according to the invention, <tb> <SEP> Figure 2: a schematic illustration of the axial piston machine corresponding to the longitudinal section of Figure 1, <tb> <SEP> Figure 3: a further schematic view of the axial piston machine in a plan view, <tb> <SEP> Figure 4: a simplified representation of Figure 3 with the controller axes drawn in,

FIG. 1 shows an axial longitudinal section through the axial piston machine according to the invention. The invention is described below using an axial piston pump, but it is explicitly pointed out that the features of the invention according to the invention can also be used in an axial piston motor without restriction. It is also pointed out that the features according to the invention can also be used for an axial piston machine which can work in a multi-quadrant operation.

On the drive shaft 1, an engine drum 2 is arranged in a rotationally fixed manner, in which a plurality of engine pistons 3 are inserted into cylinder bores 4 in the manner of a drum turret. The engine pistons 3 are each supported on the swash plate 6 via a sliding shoe 5. The swash plate is supported on the main housing 8 via a compression spring 7. When the drive shaft 1 rotates, the engine pistons 3 slide by means of their sliding blocks 5 over the sliding surface of the swash plate 6 and, depending on the swivel angle of the swash plate 6, the engine pistons 3 move in a reciprocating motion, depending on the operating mode of the axial piston machine, i.e. pump or motor operation thereby generating hydraulic energy or mechanical power.

A retaining device ensures that the running surfaces of the sliding shoes 5 of the engine pistons 3 do not lose contact with the sliding surface of the swash plate 6 even during their suction phase. The restraint device consists i.a. from a retraction plate 10 and the retraction ball 9 sitting coaxially on the drive shaft 1. The latter is pressed by spring 12 to the left in the plane of the drawing in the direction of the swash plate 6 and is supported on the retraction plate 10. As a result, the retraction plate 10 is in constant contact with the sliding blocks 5 and presses their running surfaces onto the swash plate 6. The engine drum 2 is pressed in the direction of the control plate 13 by the central spring 12.

The stroke of the engine piston 3 is predetermined by the pivot angle of the swash plate 6, which can be changed via an adjusting device 20 during operation. The adjusting lever 21 has a spherical end region on both sides, with one side of the adjusting lever 21 forming a ball joint connection with the swash plate 6 and the other side with the adjusting piston 22. The adjusting lever 21 can be rotationally symmetrical with respect to its longitudinal axis and / or be designed mirror-symmetrically with respect to a vertical axis. The adjusting lever 21 extends in the axial direction from the swash plate 6 over the control plate 13 and into a blind hole 11a, which is located inside the connection plate 11 and in which the adjusting piston 22 is guided. A control or regulating valve 30 can be accommodated within the connection plate 11.

The spherical control lever end opposite the swash plate 6 forms a ball-and-socket joint with the spherical recess in the control piston 22. The actuating piston 22 is mounted in an axially displaceable manner within the blind hole 11a of the connection plate 11. On its end face opposite the spherical recess, the actuating piston 22 shown in the exemplary embodiment has a small cylindrical extension 23 on which a compression spring of the control valve 30 can be supported. With such a structure, the position of the actuating piston 22 exerts a force on this compression spring, which is then also referred to as a feedback spring. As a result, the control or regulation in which the control or regulating valve participates is influenced by the position of the actuating piston 22, which is desired, for example, for volume flow regulation.

To limit the adjustment movement for the swash plate 6, two stops for the adjusting piston 22 in the area of the blind hole 11a. A first stop 24 for limiting the maximum pivoting angle is formed by the bottom of the blind hole 11a, so that here the maximum insertion path of the adjusting lever 21 into the blind hole 11a is limited. A second stop for the actuating piston 22 to limit the minimum pivoting angle is formed by a flat protrusion of the machine housing 8 in the area of the blind hole 11a.

The arrangement described enables the overall length of the connection plate 11 to be used to accommodate the control or regulating valve 30. This can be inserted or screwed into the connection plate 11 from the outside so that the valve 30 can be easily replaced.

In the schematic representation of FIG. 2, the axial piston machine is now shown with several hydraulic components 50, 51, 52 attached, which are stacked in a sandwich-like manner and attached to the connection plate 11 on the housing side. Such a hydraulic component is also a control valve or a regulating valve. For better differentiation from a control or regulating valve 30 which is built into the connection plate, such a hydraulic component fastened to the outer surface of the connection plate 11 is referred to as a control or regulator unit. A plurality of control units can also be attached to the outer jacket surface of the connection plate 11. Likewise, several controller units can be attached to the outer surface of the connection plate 11. Likewise, one control unit or several control units with one regulator unit or with several regulator units can be attached to the connection plate 11 in the corresponding position like the units 50, 51, 52.

Said units 50, 51, 52 mounted on the connection plate are located in the immediate vicinity of the position where a control or regulating valve 30 can be screwed into the connection plate 11 in the event that it is present. This compact arrangement offers the advantage of short oil connections, which also run in the solid valve or controller housings and the connection plate. This results in a robust construction, which is clearly advantageous in the application for mobile work machines, where particularly high and frequently occurring shock and vibration loads are present.

A specific application example of the schematic embodiment shown can be the following arrangement: <tb> <SEP> The unit 50 fastened directly to the connection plate can be an electrically controllable pressure reduction unit. The desired control pressure, which acts on the valve piston of the control valve 30, is generated at the pressure output there via an electrical control. Control valve 30 can be a volume flow control valve. The units fastened above the pressure reduction unit 50 can be a pressure cut-off 51 and a load-sensing unit 52. <tb> <SEP> The sandwich-like stacked units 50, 51, 52 can also be seen in the top view of FIG. FIG. 4 shows again the top view of FIG. 3, however with the dashed lines drawn in control or regulator axes 50a, 51a, 52a of the control or regulator units 50, 51, 52 and the central longitudinal axis of the drive shaft 1, also drawn in dashed lines is that all said axes 50a, 51a, 52a of the units 50, 51, 52 are perpendicular to the longitudinal axis of the drive shaft 2. It can also be clearly seen that, in the exemplary embodiment, the respective longitudinal axes of the drive shaft 1, the actuating lever 21, the actuating piston 22 and the regulating or regulating valve all lie on a common half-plane H1. The half-plane H1 is limited by the longitudinal axis of the drive shaft. Regardless of the position of the actuating piston, it is always the same half-plane H1.

In addition, it can be seen from FIG. 4 that all control or regulator axes 52a, 51a, 50a of units 52, 51, 50 run in pairs parallel to one another.

The control or regulator units 50, 51, 52 can be used regardless of the direction of rotation of the drive shaft or that of the engine. If the direction of rotation is changed, these units only need to be rotated by 180 ° in relation to their longitudinal direction.

[0033] Further advantages of the structural arrangement which relate to the axial piston machine according to the invention: <tb> <SEP> As a result of the slight change in the angle of the adjusting lever 21 to the central axis of the adjusting piston 22, a force transmission in the area of the adjusting piston 22 that is almost free of transverse forces is achieved. The immersion of the spherical area of the adjusting lever 21 into the inner area of the adjusting piston 22 also contributes to this.

The uniform loading of the swash plate bearing 40 due to the forces from the adjusting device 20 introduced centrally to the bearing points is particularly advantageous.

The arrangement of the control or regulating valves and the control and regulating units ensures that the installation space required for tandem operation of several axial piston machines is not blocked by them.

Claims (8)

1. Axial piston machine comprising a drive shaft, a drive unit connected to it in a rotationally fixed manner with one or more drive unit pistons, the piston stroke of which can be adjusted by a swash plate, at least one return spring acting on the swash plate and an actuating piston being supported on the swash plate, the axial piston machine at least one control or control valve or at least one control or regulating unit, characterized in that that an actuating piston is guided in the connection plate and an actuating lever acts as a coupling element between the actuating piston and swashplate and the actuating piston axis and the actuating lever axis are located on a half-plane H1 starting from the drive shaft axis. 2. Axial piston machine according to claim 1, characterized in that the adjusting piston axis runs parallel to the drive shaft axis and the adjusting lever axis is located in the half-plane H1. 3. Axial piston machine according to claim 2, characterized in that the course of the central axis of the at least one return spring is on the half-plane H1. 4. Axial piston machine according to claim 3, characterized in that the half-plane H1 runs centrally or almost centrally to the swash plate bearing. 5. Axial piston machine according to one of the preceding claims, characterized in that a control or regulator valve is in the connection plate, the axis of this control or regulating valve being on the half-plane H1 and preferably the axis of this control or regulating valve parallel to the Drive shaft is arranged. 6. Axial piston machine according to one of claims 1 to 4 or 5, characterized in that at least one control or regulator unit is arranged on the connection plate, the axis of the control or regulator unit extending at right angles to the half-plane H1. 7. Axial piston machine according to claim 6, characterized in that several units for control and / or regulation are arranged on the connection plate, each axis of such a control or regulator unit either running at right angles to the half plane H1 or running parallel to the half plane. 8. Axial piston machine according to claim 5, characterized in that each axis of the control or regulator valves built into the connection plate is oriented at right angles to at least one axis of a control or regulator unit arranged on the connection plate.