WO1994012790A1 - Measuring device for observing the displacement volume setting of axial piston engines - Google Patents

Abstract

The invention relates to a measuring device for observing the displacement volume setting of axial piston engines of any design, the displacement volumes of which can be adjusted to various values by means of a movable adjuster. The measuring device comprises a bearing surface coupled to the adjuster so that it can move therewith and a measuring sensor arrangement with at least one measuring sensor to detect changes in the position of the bearing surface, the measuring sensor and the bearing surface being each in mutual contact with a contact point. In order to be able with this measuring device to observe functions with different strokes as well, the invention proposes that, for the purposes of joint movement with the adjuster (1), the bearing surface (9) be rotatable about an axis (A) arranged at a distance from the contact point (22, 23; 26, 27; 34, 35). The angle of rotation ( alpha ) of the bearing surface (9) and the distance (x, r) determine the measuring travel (a, b) of the measuring sensor (7; 19; 30, 31) proportional to the movement of the adjuster (1).

Description

Measuring device for detecting the displacement volume setting of axial piston machines

The invention relates to a measuring device for detecting the displacement volume setting of axial piston machines according to the preamble of patent claim 1.

From DE-PS 40 22 301 such a measuring device for detecting the displacement volume setting of an axial piston machine in an inclined axis construction is known, the contact surface of which is designed as an inclined inclined surface on the swiveling control body of the axial piston machine, namely on one of the side surfaces of the Control body, which are guided by two flat and parallel to each other arranged guide surfaces of the pivot bearing. When the control body is pivoted, the inclined inclined surface is guided past the sensor by displacement of the same by a certain stroke, which is determined by the swivel path of the control body and the inclination angle of the inclined surface and is always the same regardless of the arrangement of the sensor relative to the inclined surface. This is disadvantageous in that no functions that require different strokes can be performed with the known measuring device; for example, it is not possible to operate switches with different switching paths.

It is an object of the invention to develop a measuring device of the type mentioned in the introduction so that functions with different strokes can also be performed.

This object is achieved by the characterizing features of patent claim 1. Instead of an inclined surface which can be displaced parallel to itself, a contact surface which can be rotated about an axis of rotation is used according to the invention, the rotation of which causes the sensor to be moved by a measuring path which increases with increasing distance of its contact point from the axis of rotation. In this way, several sensors with different measuring paths and thus, for example, several switches with different switching paths can be actuated with one and the same contact surface.

Here, these sensors on both sides of the preferably in the contact surface che extending axis of rotation may be arranged so that, for example, switches with the same or different switching paths can be operated when adjusting reversible axial piston machines in one or the other conveying direction.

Each sensor preferably has a measuring surface which, like that

Contact surface is flat and is each provided with two boundary edges. If the distance of the contact surface boundary edges from the

If the axis of rotation is equal to or smaller than the distance between the measuring surface boundary edges, one of the first-mentioned boundary edges slides along the measuring surface as the contact point of the contact surface when the latter rotates. In the opposite case, i.e. if the contact surface protrudes beyond the measuring surface boundary edges, one of these boundary edges represents the measuring surface contact point, which slides along the contact surface when the same rotates.

However, the measuring surface of the sensor can also be at least cylindrical with a normal sectional plane perpendicular to the axis of rotation or spherical, so that both the measuring surface and the contact surface slide along one another when the latter rotates and their contact points thus take up constantly changing distances from the axis of rotation.

According to a development of the invention, at least one sensor is slidably guided in a guide bush, which can itself be designed as a sensor.

The contact surface is preferably formed on a rotatable shaft of an adjusting device for adjusting the actuator connected to the pivotable component of the axial piston machine. The contact surface can be the groove base of a groove cut into the shaft.

Further features and advantages of the invention emerge from the remaining subclaims. The invention is illustrated below on the basis of a few preferred embodiments. Example described with reference to the drawing. Show it:

1 shows a measuring device according to a first embodiment of the

 Invention in sectional view,

Figure 2 shows a measuring device according to a second embodiment of the

 Invention in schematic representation, Figure 3 shows a measuring device according to a third embodiment of the

 Invention in a schematic representation, and

Figure 4 shows a measuring device according to a fourth embodiment of the

 Invention in a schematic representation.

The measuring device shown in Figure 1 is in an adjusting device for

Adjusting the actuator 1 of an axial piston machine, not shown, in swash plate, swash axis or swash plate construction incorporated. The axial piston machine conventionally comprises a cylinder drum which is rotatably mounted in a genause and a swash plate or swash plate which is generally referred to here as a swash plate. Depending on the design, either the cylinder drum or the swash plate is pivotally mounted for changing the displacement volume setting of the axial piston machine and is coupled to the actuator 1.

The adjusting device comprises a shaft 2, which is rotatably mounted in a bearing bore 3 of a housing 4 about its longitudinal central axis A and is coupled on the one hand to a hand lever (not shown) and on the other hand to an adjusting lever 5, which is connected to the actuator 1 via an eccentric 6 at its free end is engaged. The hand lever serves to rotate the shaft 2 in mutually opposite directions until an end position is reached, which corresponds to an end position of the actuator 1 corresponding to the respective maximum displacement volume setting of the axial piston machine.

The adjusting device further comprises a reset arrangement for resetting len of the shaft 2 rotated towards the end position and for holding it in a zero position. In Figure 2, one of the end positions is indicated with solid lines and the zero position with dashed lines. The return arrangement comprises a return element 7 with a flat end face 8, a flat counter surface 9 formed on the shaft 2, a return spring 10 and a closure part 11, which is designed as a screw consisting of a head section 12 and a bolt section 13.

The restoring element 7 is arranged in a housing 15 formed in the housing 4, from an end face 14 of the same to the bearing bore 3 perpendicular to this bore 15. This bore 15 is formed with a radially extending step 16 and has a rectangular cross section in the area between this step and the bearing bore 3 and a circular cross section in the remaining area. In the same way, the reset element 7 is formed on both sides of a radial step 17 with a rectangular cross section extending up to the end face 8 and a circular cross section.

The closure part 11 is screwed with its bolt section 13 into the bore 15 until its head section 12 bears against the housing end face 14 and accordingly limits the stroke of the restoring element 7. The restoring spring 10 is arranged in a blind bore 18 of the restoring element 7 and is pretensioned on the bolt section 13 of the closure part 11, so that it acts on the restoring element 7 in the direction of the counter surface 9 formed on the shaft 2.

This counter surface 9 is the groove base of a rectangular groove cut into the shaft 2 transversely to this and having parallel groove walls (not shown), into which the restoring element 7 engages with its rectangular cross section. The groove is open on both sides and its depth corresponds to the radius of the shaft 2, so that the radial dimension of the groove base 9 measured transversely to this is equal to the diameter 2r of the shaft 2. The longitudinal central axis L of the bore 15 lies in a the longitudinal central axis A of the shaft 2 containing level E.

The measuring device according to Figure 1 comprises a bearing surface which is identical to the counter surface 9 of the shaft 2 and is accordingly also designated by the reference number 9, and a measuring sensor 19 with a flat measuring surface 20 which corresponds in the form of a pin with a rectangular cross section in a central through bore Cross section in the restoring element 7 and in the closure part 11 is arranged displaceably and engages in the groove. The end face of the sensor 19 facing the shaft 2 is identical to the measuring face 20. The sensor 19 rests with its opposite end face against an actuating element (not shown) which is biased in the direction of the shaft 2 by means of a return spring (not shown) and which is screwed into the closure part 11 and is in this way constantly in the direction of the counter or contact surface 9 acted upon.

As FIG. 2 clearly shows, the measuring surface 20 of the sensor 19 comprises two measuring surface regions 20a, 20b of the same size on both sides of the plane E intersecting them vertically, each of which has an axial, i.e. Limiting edge 22, 23 running parallel to the longitudinal central axis A of the shaft 2 are limited at a distance x from the plane E. The end face 8 of the restoring element 7 comprises two end face regions 8a, 8b of the same size, which are arranged radially outside the measuring surface 20 and extend from this up to an axially extending boundary edge 24, 25 at a distance y from the plane E. The contact surface 9 comprises two contact surface regions 9a, 9b of the same size arranged on both sides of the plane E, each of which is delimited by an axially extending boundary edge 26, 27 with the distance r from the longitudinal central axis A. The distances x, y and r are measured in the plane of the respective surface 20, 8 and 9, respectively. The distance r is equal to the distance y.

Figure 2 shows a schematic representation of the same arrangement as Figure 1, but with the difference that the reset element 7 is connected to a dial gauge 28 for measuring its stroke or measuring path and thus simultaneously serves as a second sensor, also designated by the reference numeral 7. The sensor 19 is not provided here for actuating the safety switch 21, but also with a dial gauge 29 for measuring its measuring path connected and acted upon by a return spring, not shown, of the dial gauge 29 in the direction of the contact surface 9.

The function of the measuring device according to the invention according to Figure 2 applies equally to the measuring device and the reset arrangement according to Figure 1 and is described below:

 As shown in broken lines in FIG. 2, the shaft 2 is in a rotational position corresponding to the zero position relative to the housing 4, which corresponds to a zero position of the actuator 1 corresponding to the zero displacement volume of the axial piston machine. The correspondence is established by adjusting the adjustment lever 5 and thus the eccentric 6 accordingly (see FIG. 1). At the same time, both the sensor 7 serving as the restoring element and the sensor 19 are in their respective zero position, in which they bear completely against the contact surface 9 of the shaft 2 with their measuring surfaces 8, 20 under the force of the respective restoring spring; the distance r between the edges 26,27 is equal to the distance y between the edges 24,25. The arrangement of the contact surface 9 of the shaft 2 and the measuring surface 8 of the resetting sensor 7 on both sides of the two surfaces 8.9 perpendicularly intersecting plane E works together with the return spring 10 ei ne mutual fixation of the shaft 2 and the two sensors 7th , 19 in the zero position or zero position. In other words, the shaft 2 serves on the one hand as a stop for the sensors 7, 19 and thus prevents them from being displaced by the respective return spring beyond the zero position, and on the other hand is mainly due to the sensor 7 fixed in this way with the biasing force of the return spring 10 set in their zero position. In the case of the exemplary embodiment according to FIG. 1, the safety switch 21 is in the non-actuated state. In the case of the exemplary embodiment according to FIG. 2, both dial indicators 28, 29 are set to zero.

If the axial piston machine is to be swiveled out in one of the two conveying directions, the shaft 2 is rotated by means of the hand lever from its zero position by a corresponding angle α in the corresponding direction (clockwise in the present exemplary embodiment) and thus a pivoting movement of the adjusting lever 5 caused by a corresponding pivot angle. This pivoting movement is caused by the eccentric 6 transmit the actuator 1, which in turn causes the axial piston machine to swing out to a corresponding displacement volume.

During this rotation, the shaft 2 remains out of its zero position with only one of the two boundary edges 26, 27 (the upper boundary edge 26 in the drawing) as the contact point of the contact surface 9 in contact with the associated (in the drawing upper) measuring surface area 8a of the resetting sensor 7 and moves this against the force of the return spring 10 with the measuring path indicated by the dial gauge 28

 a = r'sin α in the direction (in the exemplary embodiments up to) defined by the bolt section 13 of the closure part 11. A radial sliding movement of the relevant contact point 26 or 27 takes place along the measuring surface 8, namely along a distance

m = y-r'cos α. The respective other boundary edge 27 or 26 of the contact surface 9 moves away from the measuring surface 8.

At the same time, the sensor 19 with the boundary edge 22, 23 (the upper edge 22 in the drawing) as the contact point of its measuring surface 20 is in contact with the associated (in the drawing upper) contact surface region 9a and is moved by this during the rotation of the shaft 2 the measuring path b = x.tgα shifted, which is indicated by the dial gauge 29 in the case of the exemplary embodiment according to FIG. 2. In the embodiment of FIG. 1, the sensor 19 switches the safety switch 21 to a position in which the latter prevents the start of the axial piston machine. During the rotation of the shaft 2 there is a radial sliding movement of the contact point 22 or 23 along the contact surface 9, namely over a distance n = x-x cosoc. The respective other measuring surface boundary edge 23 or 22 moves away from the contact surface 9 during the rotation of the shaft 2.

By returning the hand lever to its initial position, the shaft 2 is rotated back into its zero position and the adjusting lever 5 is pivoted back accordingly. A force-applying device, not shown, now resets the actuator 1 to its zero position and thus the axial piston machine to the zero displacement volume setting. Equal at the same time, the resetting sensor 7, like the sensor 19, is displaced back into the zero position by the force of the respective tensioned return spring. When the shaft 2 is rotated in the opposite direction, the direction of conveyance of the axial piston machine is reversed and the other contact surface and measuring surface areas come into contact with one another.

The measuring device according to FIG. 3 differs from that according to FIG. 2 in that instead of the sensor 19 two sensors 30, 31 are used, which are arranged on both sides symmetrically to the plane E in the resetting sensor 7, each having a spherical measuring surface 32, 33, which is in point contact with the contact surface 9 at the respective contact point 34, 35, and is connected to a dial gauge 36, 37. The function of this measuring device corresponds analogously to that of the measuring device according to FIG. 2.

The measuring device according to FIG. 4 is equipped with only one, namely the resetting sensor 7 according to FIG. Its function results from the functional description above.

Deviating from the above description, the measuring surface areas of the individual sensors can have different radial dimensions, so that they or their boundary edges determining the measuring path of the sensor are arranged at different distances from the plane E. In such a case you can use a sensor with. two measuring surface areas arranged on both sides of plane E, depending on the direction of rotation of the shaft, different measuring paths can be achieved. The same purpose is achieved with a sensor whose measuring surface is graduated so that the e.g. Measuring surface areas arranged on both sides of plane E have different distances from a plane perpendicular to plane E. The step separating the two measuring surface areas can also be arranged to the side of plane E, i.e. one of the two measuring surface areas is arranged on both sides and the other measuring surface area is arranged only on one side of plane E.

Claims

PATENT CLAIMS 1 . Measuring device for detecting the displacement volume setting of axial piston machines of any type, the displacement volume of which can be adjusted to different values by means of an adjustable actuator, the measuring device having a bearing surface coupled to the actuator for the purpose of joint movement with the same and one Sensor arrangement comprising at least one sensor for detecting changes in position of the contact surface, the sensor and the contact surface being in mutual contact with one contact point each,  characterized,  that the contact surface (9) for the purpose of common movement with the actuator (1) by a distance (x, r) from the contact point (22,23; 26,27; 34,35) arranged axis of rotation (A) is rotatable, the The angle of rotation (α) of the contact surface (9) and the distance (x, r) determine the measuring path (a, b) of the sensor (7; 19; 30,31) which is proportional to the size of the respective adjustment of the actuator (1). 2. Measuring device according to claim 1,  characterized,  that the axis of rotation (A) extends in the contact surface (9). 3. Measuring device according to claim 1 or 2, characterized, that the axis of rotation (A) runs in the center of the contact surface (9). 4. Measuring device according to at least one preceding claim,  characterized,  that the sensor arrangement comprises at least two sensors (7, 19, 30, 31), 5. Measuring device according to claim 4,  characterized,  that the sensors (30,31) are arranged on both sides of the axis of rotation (A). 6. Measuring device according to at least one preceding claim,  characterized,  that the contact surface (9) is a flat surface with two mutually spaced (2r) boundary edges (26,27). 7. Measuring device according to at least one preceding claim,  characterized,  that each sensor (7, 19) has a flat measuring surface (8, 20) facing the contact surface (9) with two boundary edges (24, 25; 22, 23) arranged at a mutual distance (2y, 2x). 8. Measuring device according to claim 6 or 7,  characterized,  that the boundary edges (26,27; 24,25; 22,23) run parallel to the axis of rotation (A). 9. Measuring device according to claim 7 or 8,  characterized,  that the boundary edges (24, 25; 22, 23) of each measuring surface (8, 20) are arranged on both sides of the axis of rotation (A). 10. Measuring device according to claim 9,  characterized, that the boundary edges (24, 25; 22, 23) of each measuring surface (8, 20) are each arranged at the same distance (y, x) from the axis of rotation (A). 11. Measuring device according to at least one preceding claim,  characterized,  that the contact point (22, 23) of each sensor (19) is arranged at a constant distance (x) from the axis of rotation (A) and, when the contact surface (9) rotates, slides along it over a distance (s). 12. Measuring device according to claim 11,  characterized,  that the contact surface (9) protrudes beyond the measuring surface boundary edges (22, 23), so that one of them represents the contact point of the measuring surface (20). 13. Measuring device according to at least one of claims 1 to 10,  characterized,  that the contact point (26, 27) of the contact surface (9) is arranged at a constant distance (r) from the axis of rotation (A) and slides along the measuring surface (8) over a distance (m) when the contact surface (9) rotates. 14. Measuring device according to claim 13,  characterized,  that the distance (r) of the boundary edges (26, 27) of the contact surface (9) is equal to or less than the distance (y) of the boundary edges (24, 25) of the measuring surface (8), so that one of the contact surface limits tongue edges (26, 27) represents the contact point of the contact surface (9). 15. Measuring device according to at least one of claims 1 to 10,  characterized, that each measuring sensor (30, 31) has a measuring surface (32, 33) facing the contact surface (9), which is at least cylindrical with a normal sectional plane or spherical so that the contact points (34, 35) run perpendicular to the axis of rotation (A) of the sensor (30, 31) and the contact surface (9) take on constantly changing distances from the axis of rotation (A) when the latter rotates. 16. Measuring device according to at least one preceding claim,  characterized,  that at least one sensor (19; 30, 31) is slidably guided in a guide bushing (7). 17. Measuring device according to claim 16,  characterized,  that the guide bush (7) is designed as a sensor. 18. Measuring device according to at least one preceding claim,  characterized,  that the contact surface (9) on a rotatable shaft (2) of an adjusting device for adjusting the actuator (1) is formed. 19. Measuring device according to claim 18,  characterized,  that the contact surface (9) is the groove base of a groove cut into the shaft (2).