Swivel Angle Measuring Device on a Hydrostatic Axial Piston Machine with Variable Stroke Volume

Abstract

A swivel angle measuring device is configured to indirectly sense a swivel angle of a swashplate or cylinder drum of an axial piston machine. The swivel angle is adjustable using an adjustment piston guided in an adjustment cylinder. The swivel angle measuring device includes a movable encoder and a transducer affixed to a housing. The encoder is formed by two permanent magnets that are carried linearly and translationally by the adjustment piston along its direction of movement and that have a distance to one other.

Claims

1. A swivel angle measuring device configured for indirectly sensing a swivel angle of a swashplate or a cylinder drum of a hydrostatic axial piston machine, the swivel angle is adjustable by an adjustment piston guided in an adjustment cylinder, the swivel angle measuring device comprising: a movable encoder; and a transducer affixed to a housing of the hydrostatic axial piston machine, wherein the swivel angle measuring device is translational, wherein the movable encoder is formed by two permanent magnets carried in a linear and translational manner by the adjustment piston along a direction of movement of the adjustment piston, and wherein the two permanent magnets have a distance to each other.

2. The swivel angle measuring device according to claim 1, wherein: each permanent magnet of the two permanent magnets has a corresponding north pole and a corresponding south pole, and the two north poles and the two south poles of the two permanent magnets are arranged along the direction of movement of the adjustment piston in alternating order.

3. The swivel angle measuring device according to claim 1, wherein: each permanent magnet of the two permanent magnets has a corresponding north pole and a corresponding south pole, and either the two north poles or the two south poles of the two permanent magnets are assigned to each other along the direction of movement of the adjustment piston.

4. The swivel angle measuring device according to claim 1, wherein: each permanent magnet of the two permanent magnets has a corresponding north pole and a corresponding south pole, each permanent magnet has a major axis extending through the south pole and through the north pole, the two major axes of the two permanent magnets are arranged perpendicular to the direction of movement of the adjustment piston, and (i) the north pole of a first permanent magnet of the two permanent magnets and the south pole of a second permanent magnet of the two permanent magnets face the transducer, and the south pole of the first permanent magnet and the north pole of the second permanent magnet face away from the transducer, or (ii) the south pole of the first permanent magnet and the north pole of the second permanent magnet face the transducer, and the north pole of the first permanent magnet and the south pole of the second permanent magnet face away from the transducer.

5. The swivel angle measuring device according to claim 1, wherein the transducer is configured to sense all possible directions of movement of the two permanent magnets in a plane of motion.

6. The swivel angle measuring device according to claim 5, wherein: the transducer has an electronic sensor component having a longitudinal axis defining a major axis of the transducer, and the major axis of the transducer is disposed transversely or longitudinally to the direction of movement of the adjustment piston.

7. The swivel angle measuring device according to claim 6, wherein: an air gap is provided between the two permanent magnets and the electronic sensor component, and a ratio of the air gap to the distance of the two permanent magnets is between 0.295 and 0.558.

8. A hydrostatic axial piston machine in a swashplate or inclined axle design, comprising: an adjustment piston guided in an adjustment cylinder and configured to adjust a swivel angle of a swashplate or cylinder drum; and a swivel angle measuring device according to claim 1.

9. The hydrostatic axial piston machine according to claim 8, wherein: the adjustment cylinder is a differential cylinder, the adjustment piston has a piston rod, a transverse pin is attached to the piston rod, and the two permanent magnets are indirectly or directly attached to an end section of the piston rod.

10. The hydrostatic axial piston machine according to claim 9, wherein the two permanent magnets are indirectly attached via a carrier component to the end section of the piston rod extending along the direction of movement.

11. The hydrostatic axial piston machine according to claim 10, wherein the carrier component is U-shaped when viewed in a sectional plane arranged transversely to the direction of movement of the adjustment piston.

12. The hydrostatic axial piston machine according to claim 11, wherein the two permanent magnets are mounted in a magnetic housing fixed to the carrier component.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0027] Principles and exemplary embodiments of the disclosure will be described in the following on the basis of the accompanying figures.

[0028] FIG. 1 shows the exemplary embodiment of the axial piston machine, as disclosed herein, with a swivel angle measuring device, as disclosed herein;

[0029] FIG. 2 shows an excerpt of the axial piston machine of FIG. 1 with the swivel angle measuring device of FIG. 1;

[0030] FIG. 3 shows an excerpt of the axial piston machine of FIG. 1 with a second exemplary embodiment of the swivel angle measuring device as disclosed herein;

[0031] FIG. 4 shows an excerpt of the axial piston machine of FIG. 1 with a third exemplary embodiment of the swivel angle measuring device as disclosed herein;

[0032] FIG. 5 shows a fourth exemplary embodiment of the swivel angle measuring device as disclosed herein;

[0033] FIG. 6 shows a fifth exemplary embodiment of the swivel angle measuring device as disclosed herein; and

[0034] FIG. 7 shows a sixth exemplary embodiment of the swivel angle measuring device as disclosed herein.

DETAILED DESCRIPTION

[0035] FIG. 1 shows an exemplary embodiment of the axial piston machine 1 according to the disclosure in a longitudinal section. It has a circumferential cylinder drum 2 at the circumference of which a plurality of cylinders 4 are formed, in each of which a piston 6 is arranged, respectively. Piston feet 8 of pistons 6 are flexibly coupled to a flange 10 of a drive shaft 12. According to the design principle of the inclined axle machine, a center axis of the cylinder drum 2 is inclined towards a center axis of the drive shaft 12.

[0036] In order to be able to change the inclined positions of the two center axes with respect to each other and thus the swivel angle of the cylinder drum 2, the latter has a concave abutment surface that is tensioned against a corresponding convex abutment surface of a control lens 14. Centrally engaged with the control lens 14 is a transverse pin 16 radially inserted into an adjustment piston 18. The adjustment piston 18 is guided in an adjustment cylinder 20 of an adjustment device along a direction of movement 24. The adjustment cylinder 20 is embodied as a double acting differential cylinder. Accordingly, the adjustment piston 18 is composed of a piston section 21 and a piston rod 22, from which the transverse pin 16 projects radially towards the control lens 14.

[0037] A central axis 24 of the piston rod 22 and thus also of adjustment cylinder 20 defines the direction of movement 24, wherein in FIG. 1, a movement to the left corresponds to a reduction of the swivel angle and thus a reduction of the stroke volume of axial piston machine 1, while a movement to the right corresponds to an increase of the swivel angle and thus an increase of the stroke volume of the axial piston machine 1.

[0038] A first exemplary embodiment of the swivel angle measuring device 100 according to the disclosure is disposed on a free end section 22a of the piston rod 22. It has a U-shaped carrier component 25 made of sheet metal, which extends into a measuring housing 23 parallel to the central axis 24. The carrier component 25 is fixed to the free end section 22a of the piston rod 22 by means of two pins and a screw. It carries two rod-shaped permanent magnets 26. More specifically, the two permanent magnets 26 are inserted or injected into a trough-like magnetic housing 28, which is attached to a central base side of the U-shaped carrier component 25. Two legs, of which only one leg is shown in FIG. 1 due to the section, extend (in FIG. 1 downwards) away from the permanent magnets 26 and their magnetic housing 28.

[0039] As already stated, the carrier component 25 extends with the magnetic housing 28 attached thereto and the two permanent magnets 26 mounted therein into the stationary measuring housing 23. At the maximum swivel angle of the axial piston machine 1 shown in FIG. 1, only the first permanent magnet 26 and a part of the second permanent magnet 26 are disposed in this measuring housing 23. At a minimum swivel angle, both permanent magnets 26 are disposed entirely in this measuring housing 23.

[0040] In a through-hole recess of the stationary measuring housing 23, a transducer 30, configured as a Hall sensor, is arranged, having a socket which is accessible on the outer side of the measuring housing 23.

[0041] FIGS. 2 to 4 each show the same section of the measuring housing 23 with three different exemplary embodiments of the swivel angle measuring device 100; 200; 300, as disclosed herein.

[0042] An electronic sensor component, which is housed in this end section of the transducer 30 and is therefore not visible, is mounted in an end section of the transducer 30 facing the permanent magnet 26 (shown as lower in FIGS. 2 to 4) and projecting into the measuring housing 23. In the exemplary embodiments shown in FIGS. 2 to 4, the axis of this sensor component and thus also a major axis 30b of the end section of the transducer 30 are arranged perpendicular to the drawing plane and thus transversely to the direction of movement 24 of the adjustment piston 18.

[0043] In the exemplary embodiment according to FIGS. 1 and 2, the rod-shaped permanent magnets 26 are disposed such that first a south pole S of the first permanent magnet 26, then its north pole N, then the south pole S of the second permanent magnet 26 and finally its north pole N are arranged along the direction of movement 24. A four-pole arrangement is thus formed from the two permanent magnets 26.

[0044] In the exemplary embodiment according to FIG. 3, the two rod-shaped permanent magnets 26 are arranged such that first a north pole N of the first permanent magnet 26, then its south pole S, then the south pole S of the second permanent magnet 26 and finally its north pole N are arranged along the direction of movement 24. A three-pole arrangement is thus formed from the two permanent magnets 26.

[0045] In the exemplary embodiment according to FIG. 4, the permanent magnets 126 are configured such that they have the two poles N, S on their long opposing sides. The first permanent magnet 126 has its north pole N on the side facing the transducer 30, while its south pole S faces the carrier component 25. Conversely, the second permanent magnet 126 has its south pole S on the side facing the transducer 30, while its north pole N faces the carrier component 25.

[0046] FIGS. 5 to 7 show a further exemplary embodiment of the swivel angle measuring device 200; 300; 400, as disclosed herein.

[0047] As already stated with reference to FIGS. 1 to 4, an electronic sensor component is mounted in the end section of the transducer 30 facing the permanent magnet 26 (shown as lower in FIGS. 5 to 7). The axis of this sensor component and thus also the major axis 30b of the end section of the transducer 30 is arranged parallel to the drawing plane and thus parallel to the direction of movement 24 in the exemplary embodiments shown in FIGS. 5 to 7.

[0048] In the exemplary embodiment according to FIG. 5, the rod-shaped permanent magnets 26 are arranged such that first a south pole S of the first permanent magnet 26, then its north pole N, then the south pole S of the second permanent magnet 26 and finally its north pole N are arranged along the direction of movement 24. A four-pole arrangement is thus formed from the two permanent magnets 26.

[0049] In the exemplary embodiment according to FIG. 6, the rod-shaped permanent magnets 26 are arranged such that first a north pole N of the first permanent magnet 26, then its south pole S, then the south pole S of the second permanent magnet 26 and finally its north pole N are arranged along the direction of movement 24. A three-pole arrangement is thus formed from the two permanent magnets 26.

[0050] In the exemplary embodiment according to FIG. 7, the permanent magnets 126 are configured such that they have the two poles N, S on their long opposing sides. The first permanent magnet 126 has its south pole S on the side facing the transducer 30, while its north pole N faces the carrier component 25. Conversely, the second permanent magnet 126 has its north pole N on the side facing the transducer 30, while its south pole S faces the carrier component 25.

[0051] The distance MLS between the two permanent magnets 26 may be 10.2 mm. The air gap AG between the end section of the transducer 30 configured as a Hall sensor and the permanent magnet 26 may be 4.35 mm+/1.34 mm.

[0052] The two permanent magnets 26; 126 may be spaced apart from one another and the transducer 30 arranged such that the detectable range of motion of the adjustment piston 18 is 60 mm.

[0053] In the drawings FIG. 1 as well as FIG. 2 to FIG. 4, the arrangement of the sensor 30 to the two magnets 26 is shown in an orientation rotated by 90 compared to the illustration in FIG. 5 to FIG. 7. Any spatial installation location between the sensor 30 and the magnets 26 may be selected as long as the magnets 26 execute a recurring defined direction of movement along the major axis. In other words: Any spatial installation location between the sensor 30 and the magnets 26 may be selected as long as the magnets 26 perform a recurring defined movement along their direction of movement 24 (center axis 24) relative to the major axis 30b of the sensor 30.

LIST OF REFERENCE NUMBERS

[0054] 1 Axial piston machine [0055] 2 Cylinder drum [0056] 3 Cylinder [0057] 4 Piston [0058] 8 Piston foot [0059] 10 Flange [0060] 12 Drive shaft [0061] 14 Control lens [0062] 16 Transverse pin [0063] 18 Adjustment piston [0064] 20 Adjustment cylinder [0065] 21 Piston section [0066] 22 Piston rod [0067] 22a Free end section [0068] 23 Measuring housing [0069] 24 Center axis/direction of movement [0070] 25 Carrier component [0071] 26 Permanent magnet [0072] 28 Magnet housing [0073] 30 Transducer [0074] 30b Major axis [0075] 100 Swivel angle measuring device [0076] 126 Permanent magnet [0077] 200 Swivel angle measuring device [0078] 300 Swivel angle measuring device [0079] 400 Swivel angle measuring device [0080] 500 Swivel angle measuring device [0081] 600 Swivel angle measuring device [0082] AG Air gap [0083] MLS Distance