EP0525507B1 - Device for adjusting the actuator for displacement volume control of a hydrostatic machine - Google Patents

Description

The invention relates to a device according to the preamble of claim 1, which is provided for adjusting the actuator for the displacement of a hydrostatic machine.

Devices of this type are known from practice and are shown in FIGS. 3 and 4 using an exemplary embodiment with hydraulic actuation of the actuator of a reversible hydrostatic machine, FIG. 4 being a section along the line II-II in FIG. 3. The shaft 1 of this known device is in hydraulic connection with the actuator 4 via two hydraulic lines 2, 3 and is designed to control the hydraulic loading thereof as a control shaft of a rotary valve with feedback. The feedback consists of a shaft 6 surrounding the shaft 6, which is rotatably mounted in the housing 5, and a return element 7 which connects it to the actuator 4 and is pivotally mounted in the housing 7. A hand lever 8 is used to rotate the shaft 1 in opposite directions until it is reached an end position which corresponds to an end position of the actuator 4 corresponding to the respective maximum displacement volume setting of the hydrostatic machine. The reset arrangement of this known device comprises an approximately half inserted into the shaft 1 reset pin 9, the free end protruding from the shaft 1 engages between two axially displaceable reset bolts 10 within the housing 5, which are coaxial to one another and transverse to the shaft 1 and transverse to Reset pin 9 arranged and held by the pressure of a spring 11 in contact with the latter.

If the springs 11 have the same characteristics and are in force equilibrium, the shaft 1 is in a rotational position referred to as zero position relative to the housing 5, which corresponds to a zero position of the actuator 4 corresponding to the zero displacement volume setting of the hydrostatic machine. Rotation of the shaft 1 in the direction of one of its end positions results in a corresponding pivoting movement of the reset pin 9 and thus in the same direction displacement of both reset pins 10 in the corresponding direction. The resulting Force imbalance between the springs 11 is available for returning the shaft 1 to its zero position.

The known device is disadvantageous in that as a result of different fatigue behavior of the springs 11 on the zero position shaft 1 there may be a force imbalance which causes a further rotation of the shaft 1 into a rotational position in which the force balance is achieved, but the shaft does not assume the zero position; the repeatable exact setting of the hydrostatic machine to zero displacement is therefore not guaranteed. This disadvantage is particularly critical in the case of zero overlap at the control edges of the rotary valve. Another disadvantage is the undesirably large design effort.

It is an object of the invention to further develop a device of the type mentioned at the outset in such a way that the construction effort is reduced and the repeatable precise setting of the hydrostatic machine to zero displacement volume is ensured even after prolonged use.

This object is achieved by the characterizing features of claim 1.

In the zero position, the restoring element according to the invention rests with its contact areas on the contact surface of the shaft as a result of its application of force, for example by a spring, and fixes the latter in its zero position due to the arrangement of its contact areas on both sides of the plane that approximately perpendicularly intersects the contact surface and contains the shaft axis of rotation . When rotating, the shaft moves away from its zero position with its contact surface from one of the two contact areas, but remains in contact with the other and, via this, gives the restoring element a movement impulse in the manner of a cam against the restoring force of the spring. In this way, the shaft and thus the restoring element are rotated or displaced into an end position or end position, which is preferably adjustable by means of a stop, and which corresponds to a specific displacement volume setting of the hydrostatic machine. The restoring force the spring, which is tensioned at the same time, is available for moving the restoring element back into the zero position and for fixing the shaft in the corresponding zero position. Since only a single force-acting device, such as the aforementioned spring, acts on the restoring element, no force imbalance and thus no change in the zero position of the shaft can occur due to the fatigue thereof, as is known in the prior art. In this way, the repeatable precise setting of the shaft and thus the hydrostatic machine into the zero position or to the zero displacement volume setting is ensured. Another advantage of the device according to the invention is that only a single force-actuated restoring element is required for both non-reversible and reversible hydrostatic machines, and thus the design effort is more than halved compared to the prior art.

The contact areas are preferably the edge areas of a flat contact surface which runs in the longitudinal direction of the shaft and whose surface portion located between the edge areas comprises the further contact areas.

Further features and advantages of the invention result from subclaims 4 to 12.

Fig. 1

eine Schnittdarstellung eines ersten Ausführungsbeispiels der erfindungsgemäßen Vorrichtung,

Fig. 2

einen Schnitt entlang der Linie IV-IV in Figur 1, der ein Rückstellelement einer ersten Ausführungsart darstellt,

Fig. 3 und 4

Schnittdarstellungen einer bekannten Vorrichtung,

Fig. 5 bis 7

je eine vergrößerte Schnittdarstellung eines Rückstellelements einer zweiten Ausführungsart in jeweils verschiedenen Stellungen,

Fig. 8

eine Schnittdarstellung eines zweiten Ausführungsbeispiels der erfindungsgemäßen Vorrichtung als hydraulisches Ansteuergerät mit einem Drehventil,

Fig. 9

einen Schnitt entlang der Linie IX-IX in Figur 8, und

Fig. 10 bis 12

schematische Darstellungen des Drehventils nach den Figuren 8 und 9 in verschiedenen Stellungen.

The device according to the invention is described in more detail below on the basis of a few preferred exemplary embodiments with reference to FIGS. 1, 2 and 5 to 12 - FIGS. 3 and 4 show sectional representations of the device known from the prior art. Show it:

Fig. 1

2 shows a sectional illustration of a first exemplary embodiment of the device according to the invention,

Fig. 2

2 shows a section along the line IV-IV in FIG. 1, which represents a reset element of a first embodiment,

3 and 4

Sectional views of a known device,

5 to 7

each an enlarged sectional view of a reset element of a second embodiment in different positions,

Fig. 8

2 shows a sectional illustration of a second exemplary embodiment of the device according to the invention as a hydraulic control device with a rotary valve,

Fig. 9

a section along the line IX-IX in Figure 8, and

10 to 12

schematic representations of the rotary valve according to Figures 8 and 9 in different positions.

In the following description, components of the device according to the invention and of the device according to FIGS. 3 and 4, known from the prior art, of essentially the same construction are designated with the same reference numerals.

The device according to the invention according to FIGS. 1 and 2 comprises a housing 5, a shaft 12, a hand lever 8, a reset arrangement which consists of a spring 11, a reset element 13 acted upon by it and a closure part 14, and an adjustment arrangement consisting of an adjustment lever 15 and an eccentric 16 which is in engagement with an actuator 4 for the displacement volume of a hydrostatic machine, not shown.

The shaft 12 is rotatably supported about its axis of rotation 17 coinciding with its longitudinal center axis in a bearing bore in the housing 5, from which it projects with one end to which the hand lever 8 is attached. In the area of its opposite end, which is flush with the housing 5, the shaft 12 has an axially accessible axial threaded bore which opens into a radial blind bore in the shaft 12. The adjusting lever 15 passes through a recess 18 in the housing 5 and engages with one end in the radial blind bore in which it is held firmly by a screw 19 screwed into the axial threaded bore and adjustable from the outside. The Recess 18 has the shape of a circular sector in order to enable the pivoting movement of the adjusting lever 15 that takes place when the shaft 12 rotates. The eccentric 16 is fastened to the free end of the adjusting lever 15 protruding from the housing 5 or the recess 18. By turning the adjusting lever 15 within the blind bore - for example by means of a screwdriver engaging in a slot 60 in the eccentric 16 - the exact zero position of the actuator 4 can be set and fixed by means of the screw 19.

In the area facing the hand lever 8 to the side of the circular sector-shaped recess 18, a stepped bore 20 in the housing 5 is formed offset by 90 ° relative to the latter. It extends transversely to the shaft 12 from a housing wall 21 to the bearing bore bearing the shaft 12. The closure part 14 in the form of a screw consisting of a head section 22 and a bolt section 23 is screwed into the larger diameter section of the bore 20 and is formed with a central stitch bore 24 which passes through the bolt section 23 with a larger diameter and ends in the head section 22 with a smaller diameter . The restoring element 13 in the form of a cylindrical bolt is slidably guided with a certain stroke in the section of smaller diameter of bore 20 and in the section of larger diameter of tap hole 24 and has a central tap hole which forms a cavity 25. The spring 11 is arranged in this cavity 25 and in the tap hole 24 with prestress. It is supported on the bottom 26 of the tap hole 24 and acts on the cavity floor 27 of the cavity 25.

The free end of the restoring element 13 facing the bearing bore for the shaft 12 is provided with a central projection 28 which engages in a groove 29 cut into the shaft 12 transversely to this with such little play that it fixes the shaft 12 in the axial direction. The groove 29 is open on both sides and its depth corresponds to the shaft radius, so that the width of the groove base 30 measured transverse to the shaft longitudinal axis is equal to the shaft diameter. The height of the shoulder 28 corresponds to the depth of the groove 29, so that in the rotational position shown in Figure 4 of the shaft 12 relative to Housing 5 resets the restoring element 13 as a result of the force exerted by the spring 11 with the flat top of its shoulder 28, which is designated as the contact surface 31 (FIG. 7), on the flat groove base 30 of the shaft 12, which is designated as the contact surface.

The second embodiment of the resetting arrangement shown in FIGS. 5 to 7 differs from the first embodiment according to FIGS. 3 and 4 only in that its closure part 32 has the shape of a bolt provided with the tap hole 24 or a hollow cylinder which is closed on one side, by the closed cylinder The end of an externally adjustable stop 33, consisting of a threaded pin that can be locked by means of a screw, protrudes for a sleeve 34 that can be displaced in the tap hole 24. The restoring element 13 is arranged displaceably in the remaining part of the tap hole 24 with the same stroke as in FIGS. 1 and 2 and is acted upon in the same way by the spring 11 passing through the sleeve 34.

The function of the device according to the invention according to the first embodiment is described in more detail below with reference to Figures 2 and 5 to 7. FIGS. 2 and 5, 6 show the shaft 12 in a rotational position, referred to as zero position, relative to the housing 5, which corresponds to a zero position of the actuator 4 corresponding to the zero displacement volume setting of the hydrostatic machine. The correspondence is established by adjusting the adjustment lever 15 and thus the eccentric 16 accordingly (see FIG. 2). At the same time, the restoring element 13 is in its zero position, in which it lies completely against the contact surface 31 of the contact surface 30 of the shaft 12 under the force of the prestressed spring 11. The arrangement of the contact surface 30 and the contact surface 31 on both sides of a plane E intersecting both surfaces 30, 31 perpendicularly and containing the shaft axis of rotation 17, together with the spring 11, causes the shaft 12 and the restoring element 13 to be mutually fixed in the zero position or Zero position. In other words, the shaft 12 serves on the one hand as a stop for the restoring element 13 and thus prevents it from being displaced by the spring 11 beyond the zero position, and on the other hand is reset by the restoring element 13 fixed in this way with the biasing force of the spring 11 in its zero position. location fixed.

If the hydrostatic machine is to be swiveled out in one of the two conveying directions, the shaft 12 is rotated out of its zero position by a corresponding angular amount in the corresponding direction by means of the hand lever 8 and thus causes a pivoting movement of the adjusting lever 15 by a corresponding swivel angle. This pivoting movement is transmitted from the eccentric 16 to the actuator 4, which in turn causes the hydrostatic machine to pivot out to a corresponding displacement.

During this rotation, the shaft 12 remains out of its zero position with only one of the two edges 35 and 36 of its contact surface 30 running in the longitudinal direction of the shaft (the left edge 36 in FIG. 7 in contact with the contact surface 31 of the restoring element 13 and displaces it the latter in the manner of a cam against the restoring force of the spring 11 in the direction of or up to the end position defined by the stop 33 and the sleeve 34. A radial sliding movement of the relevant edge 35 or 36 takes place along the contact surface 31, of the the respective other edge 36 or 35 moves away, namely in their respectively assigned edge area 37 or 38 along a distance which corresponds to the angle of rotation of the shaft 12. When the shaft 12 rotates to the end position with the edges 35 or 36 contacting edge regions 37 and 38, hereinafter referred to as contact regions, can be used when using more wear-resistant material for the contact surface 30 ch show signs of wear over a longer period of time. The remaining surface portions 39, 40 of the contact surface 31, located on both sides of the plane E, between the contact regions 37, 38 thereof are wear-free since no sliding movements take place between them and the corresponding surface portions of the contact surface 30; the latter surface portions are immediately lifted from the former surface portions 39 and 40, which are referred to here as further contact areas, when the shaft rotates. These further contact areas 39, 40 ensure that the shaft 12 is fixed in its zero position in a repeatable manner even if there are signs of wear on the contact or edge areas 37, 38. Fig. 7 shows the end position of the shaft 12 which can be reached by turning counterclockwise, in which the reset element 13 and the actuator 4, not shown, their Take end positions that correspond to the maximum displacement volume setting of the hydrostatic machine.

By returning the hand lever 8 to its initial position, the shaft 12 is rotated back into its zero position and the adjusting lever 15 is accordingly pivoted back. A force-applying device, not shown, now resets the actuator 4 to its zero position and thus the hydrostatic machine to the zero displacement volume setting. At the same time, the restoring element 13 is moved back into its zero position by the force of the tensioned spring 11, in which it fixes the zero position of the shaft 12.

The device shown in Figures 8 to 12 according to the second embodiment of the invention differs from the first embodiment of FIGS. 1 and 2 by the adjustable stop 33 according to Figures 5 to 7 and by training as a hydraulic control device for the actuator 4 with a Shaft 1, which is designed as a control shaft of a rotary valve with feedback. Otherwise, both devices are of the same construction.

The shaft 1 is rotatably mounted in a bushing 6 arranged rotatably in the bearing bore of the housing 5 and, in the region facing the hand lever 8, is provided on the side of the groove 29 at diametrically opposite points, each with a recess forming a control chamber 41, 42. In the area of these control rooms 41, 42, the socket 6 has four through openings 43 to 46, each offset by 90 ^° , to which four connection channels 47 to 50 in the housing 5 are assigned. The diametrically opposite connection channels 47, 49 lead to the tank, not shown, or to a hydraulic pressure medium source, also not shown. The remaining connection channels 48, 50 are connected via hydraulic lines 2 and 3 to pressure chambers of the actuator 4, not shown.

The shaft 1 with the control chambers 41, 42, the socket 6 with the through openings 43 to 46 and the connecting channels 47 to 50 represent the rotary valve. The return comprises the socket 6 and a return element 7 of the shape shown in FIGS. 3 and 4 Adjustment lever 15, which the 3 and 4 penetrates the same circular sector-shaped recess 18, with one end engaging in an incision 51 in the actuator 4 and with the other end via a ball 52 in a recess in the bushing 6. A part of the ball 52 protruding into the area of the shaft is received in the shaft 1 with sufficient play in an annular, transverse groove 53. In this way, the rotary movements of the shaft 1 and the bushing 6 which are otherwise blocked by the ball are made possible. The return element 7 is pivotally mounted within the recess 18 about a cranked part 54 of a pin 55. The pin 55 is rotatably arranged in corresponding bores running parallel to the shaft 1 in the housing 5, from which it projects with a threaded end. By turning the pin 55 within the bores, the exact zero position of the actuator 4 can be set and fixed by means of a nut 56. The bushing 6 also has an annular recess 57 in the region of the groove 29, which enables the bushing 6 to rotate undisturbed by the restoring element 13.

The function of the device according to FIGS. 8 and 9 corresponds in particular with respect to the reset element 13 to that of the device according to FIGS. 1 and 2. Differences arise only from the type of actuation of the actuator and the feedback of the position of the same to the actuating rotary valve. Only these differences are described below with reference to FIGS. 9 to 12:
FIGS. 9 and 10 show the shaft 1 in its zero position and accordingly the reset element 13 and the actuator 4 in their respective zero position, which corresponds to the zero displacement volume setting of the hydrostatic machine. As shown in FIG. 10, the bushing 6 is also in a rotational position corresponding to the zero position of the shaft 1, also referred to as a zero position, in which its through openings 43 to 46 are aligned with the connecting channels 47 to 50, the connections of the however, the hydraulic lines 2, 3 to the pressure chambers of the actuator 4 leading connection channels 48, 50 are blocked by the shaft 1 with the connection channels 47 and 49 leading to the pressure medium source and the tank. The actuator 4 is thus hydraulically locked in its zero position.

To pivot the hydrostatic machine in one of the two conveying directions, the shaft 1 is rotated out of its zero position in the corresponding direction, counterclockwise in FIG. 11 and into its end position, so that its control spaces 41, 42 are the pressure spaces of the Connect the actuator 4 to the pressure medium source and the tank, the socket 6 still remaining in its zero position. In the example shown in FIG. 11, the left pressure chamber 42 of the actuator 4 is connected to the pressure medium source via the line 2, the connection channel 50, the through openings 46, 45 and the connection channel 49, while the right pressure chamber of the actuator 4 is connected via the left control chamber 42 the line 3, the connecting duct 48, the through opening 44, the right control chamber 41, the through opening 43 and the connecting duct 47 to the tank is relieved. In this way, the actuator 4 is displaced in the direction of its end position - to the right in FIG. 12 - and the hydrostatic machine is pivoted out accordingly.

The return element 7 transmits this displacement of the actuator 4 to the bushing 6, which is thereby rotated - counterclockwise in FIG. 12 - until, when the actuator 4 has reached its end position shown in FIG. 12, the same rotational position relative to the shaft 1 as in Figure 10. As a result, the connections of the pressure chambers of the actuator 4 to the pressure medium source and the tank are interrupted and in this way the actuator 4 is hydraulically locked in its end position.

When the shaft 1 is rotated back to its zero position shown in FIG. 10 for the purpose of setting the hydrostatic machine to zero displacement volume, it assumes a rotational position mirror-inverted with respect to the rotational position in FIG. 11 relative to the bushing 6, in which those shown in FIG Connections are reversed and consequently the actuator 4 is moved back to its zero position by feedback of its respective position via the feedback element 7 to the socket 6.

Claims (12)

1. Device for adjusting the setting member for the displacement volume of a hydrostatic machine, having a shaft (1, 12) connected with the setting member (4) for the adjustment of the same, which shaft is mounted in a housing (5) turnable around its longitudinal axis (17), having a return arrangement extending transversely of the shaft, in engagement with the shaft, which arrangement - when the shaft is in a zero disposition - takes up a corresponding zero position and is moveable out of this position by means of rotation of the shaft against a return force,
   characterised in that,
   the shaft (1, 12) has a bearing surface (30) which contains the longitudinal axis (17) of the shaft or lies parallel thereto, in that the return arrangement has a return element (13) acted on by force in the direction of zero position, which element - in its zero position - bears against the bearing surface (30) with respective contact regions (37, 38) to the two sides of a plane (E) cutting the bearing surface vertically and containing the shaft longitudinal axis (17), and fixes the shaft (1, 12) it its zero disposition, and in that upon rotation of the shaft (1, 12) out of its zero disposition the bearing surface (30) displaces one of the two contact regions (37 or 38) against the force of the return element (13) and thereby the other contact region (38 or 37) distances itself from the bearing surface (30).
2. Device according to claim 1,
   characterised in that,
   the contact regions (37, 38) are the edge regions, running in the shaft longitudinal direction, of a flat contact surface (31) formed on the return element (13), the surface portion of which lying between the edge regions forms further contact regions (39, 40).
3. Device according to claim 1 or 2,
   characterised in that,
   the bearing surface (30) is a flat surface.
4. Device according to any preceding claim,
   characterised in that,
   the bearing surface (30) is the groove floor of a groove (29) cut into the shaft (1, 12).
5. Device according to claim 4.
   characterised in that,
   for the purpose of axial fixation of the shaft (1, 12), the return element (13) engages into the groove (29) with appropriately little play.
6. Device according to claim 4 or 5,
   characterised in that,
   the width of the groove floor (30), measured transversely of the shaft longitudinal axis, is substantially equal to the shaft diameter.
7. Device according to any preceding claim,
   characterised in that,
   the return element (13) is moveable between the zero position and an end position determined by means of an adjustable stop (33).
8. Device according to any preceding claim,
   characterised in that,
   the shaft (12) is mechanically connected to the setting member (4) via an adjustment arrangement (15, 16).
9. Device according to claim 8,
   characterised in that,
   the adjustment arrangement (15, 16) has an eccentric (16) for bringing the zero disposition of the shaft (12) into agreement with a zero position of the setting member (4) corresponding to the zero displacement volume setting of the hydrostatic machine.
10. Device according to any of claims 1 to 7,
    characterised in that,
    the shaft (1) is hydraulically connected with the setting member (4).
11. Device according to claim 10,
    characterised in that,
    the shaft (1) is formed as control shaft of a rotary valve (1, 41, 42; 6, 43 to 46; 47 to 50) for control of the hydraulic action on the setting member (4), in order through rotation of the shaft out of its zero disposition to swing the setting member out of the zero position into an end position corresponding to the maximum displacement volume of the hydrostatic machine.
12. Device according to claim 11,
    characterised by a restoring arrangement (6, 7) associated with the rotary valve (1, 41, 42; 6, 43 to 46; 47 to 50) having a sleeve (6) surrounding the shaft (1) and a restoring element (7) connecting the sleeve with the setting member (4) for transferring the setting movement of the setting member (4) to the sleeve (6) in such a manner that the sleeve interrupts the hydraulic action on the setting member (4) when the setting member is located in the zero position and when it is located in the end position.

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