WO2013029971A1

WO2013029971A1 - Clamping lever arrangement, method for producing a clamping lever, and actuation unit

Info

Publication number: WO2013029971A1
Application number: PCT/EP2012/065778
Authority: WO
Inventors: Steffen Loritz; Peter Schlotter
Original assignee: Robert Bosch Gmbh
Priority date: 2011-09-02
Filing date: 2012-08-13
Publication date: 2013-03-07
Also published as: DE102011112215A1

Abstract

Disclosed are a clamping lever arrangement, a method for producing a clamping lever of a clamping lever arrangement of said type, and an actuation unit of a hydraulic machine having a clamping lever arrangement of said type, wherein the clamping levers are produced using precision blanking and stamping techniques.

Description

Clamping lever arrangement, method for producing a clamping lever and Ansteuerqerät

description

The invention relates to a tensioning lever assembly according to the preamble of claim 1, a method for producing a tensioning lever of a tensioning lever assembly and a driving device of a hydraulic machine.

A generic tension lever assembly is known from DE 2008 048 507 A1 and DE 195 40 654 C1.

These documents disclose a drive device which can be used for example for adjusting a swivel angle of a swash plate of an axial piston machine. The adjustment is made indirectly or directly via an actuating piston, which is adjustable via a control piston. Control piston and actuating piston are in operative connection with a reset lever, on which two clamping levers are pivotally mounted, whose end portions are connected by means of a tension spring. When adjusting the control piston arranged in the adjustment clamping lever is moved against the force of the tension spring. The clamping lever thus acts on the control piston against the electrically or electrohydraulically applied actuating force in the return direction. The control position of the control piston is reached when the spring force is in equilibrium with the electrically or electrohydraulically applied actuating force. When eliminating this force, for example, by Stromlosschalten an electromagnet or by setting a going to zero control pressure difference on the control piston, this is put back by the force of the tension spring.

In the prior art, the two clamping levers are made by investment casting and then need to be machined. It has been shown that manufacturing variations in investment casting are so great that the tension levers can not always be made to measure even through mechanical reworking, so that the scrap content is high due to the inaccuracies during casting. In addition, the mechanical post-processing is very complicated, so that for a processing time is comparatively long and also the device-technical effort for processing (casting tool, mechanical post) is considerable and significantly determines the price of the clamping lever assembly.

In contrast, the invention has for its object to provide a clamping lever assembly and a control device that can be produced with reduced manufacturing complexity and a simplified method.

This object is achieved with respect to the clamping lever assembly by the combination of features of claim 1, in terms of the method by the features of claim 12 and with respect to the Ansteuergerates by the features of the independent claim 13.

Advantageous developments of the invention are the subject of the dependent claims.

The tensioning lever assembly according to the invention is provided in a device for position feedback of a control piston for adjusting a delivery or displacement volume of a hydraulic machine. The tensioning lever arrangement has at least one tensioning lever, which is pivotally mounted with a lever eye, which is connected to a lever shaft. The lever eye protrudes in the direction of the pivot axis relative to the lever shaft. At the end portion of the lever shaft a constriction is formed for hanging a tension spring. According to the invention, the tensioning lever is produced by stamping / fine blanking embossing. Such stamping is done in a follow-up tool, wherein first the molded part is formed (stamped) and then brought by cutting in the final shape. A post-processing of the clamping lever is in such a punching embossing, also called fine blanking embossing, not required, so that the manufacturing cost is significantly lower than the prior art described above. When punching embossing Although the tool costs for the fineblanking embossing tool are slightly higher than the molding costs during investment casting; However, this investment is far outweighed by the significantly reduced production time and the significantly higher quality and thus the reduced reject rate. Such a fine blanking embossing tool makes it possible to completely reshape the clamping lever including the relatively complex lever eye, with a very small scattering of the individual dimensions is observed. This stamping also leads to a clamping lever with increased strength over a precision casting, so that the fatigue strength of the clamping lever assembly is improved according to the prior art.

According to the inventive method, the clamping lever of the clamping lever assembly is produced by stamping.

According to a further aspect of the invention, a control device of a hydro- machine, for example, an axial piston machine with a clamping lever assembly in the sense of claim 1 is executed.

In a preferred embodiment of the invention, the clamping lever assembly has two clamping levers, which are designed to be identical in principle and are rotated by 180 ° to each other, wherein the lever eyes remain aligned with each other. At the two spaced-apart end portions of the clamping lever, the tension spring is then suspended.

According to the invention, the lever eye can be stepped back to the lever shaft.

In a preferred embodiment, downgrading occurs in a cascade shape through at least two stages. In this case, an adjacent to the lever eye level can be designed as a tangential and an adjacent to the lever shaft level as a cross-step, which runs approximately transversely to the lever longitudinal axis in this area.

In such a variant, it is preferred if the height extent of the tangential stage is greater than that of the transverse step. The transverse step preferably runs at an acute angle to the tangential stage.

In a variant of the invention, a constriction formed as a spring system is formed at the end portion of each lever shaft, wherein in the transition region to the constriction on the lever shank an inclined surface is formed.

This slope is made at an angle of less than 45 °, preferably 30 °.

In one embodiment of the invention, the constriction tapers towards a vertex.

In one embodiment of the invention, the inclined surface in extension of the vertex is at least partially roof-shaped.

The overall height of the clamping lever pair is particularly low when the lever eye is set on the other hand in the pivot axis direction with respect to the lever shaft back. In a preferred embodiment, a single stage is executed.

Preferred embodiments of the invention are explained in more detail below with reference to schematic drawings.

Show it

1 shows a partial representation of a control device of an axial piston machine, FIG. 2 shows a three-dimensional illustration of a tension lever arrangement of the control device according to FIG. 1,

FIG. 3 shows a plan view of the tension lever arrangement according to FIG. 2,

FIG. 4 shows a plan view of a tensioning lever of the tensioning lever arrangement,

FIGS. 5, 6, 7 details of the tensioning lever according to FIG. 4,

Figure 8 is a top view of the tensioning lever according to Figure 4 and

9 is a bottom view of the clamping lever according to FIG. 4 FIG. 1 shows, in a highly simplified manner, a partial region of a drive device 1 for adjusting a hydraulic axial piston machine, which is designed in a swash plate design. In such hydraulic machines, the swash plate is pivoted indirectly or directly via an actuating piston 2. This one is about one

Centering spring assembly 4 biased in the illustrated basic position and can be adjusted by applying a control pressure difference in two control chambers 6, 8 for pivoting the swash plate. The control pressure difference is adjusted via a control piston 10 of the control unit 1. This can be adjusted by electromagnets or by applying a control pressure difference from its illustrated neutral position to regulate in control lines 12, 14, the control pressure difference. The return of the actuating piston 2 and the control piston 10 via a return device 16. This has a return lever 18, whose upper end portion in Figure 1 is connected to the actuating piston 2 and which is mounted in a housing 20 of the drive device 1 pivotally about an axis 22. On this a pair of clamping levers with two clamping levers 24, 26 is pivotally mounted, wherein remote from the axis 22 end portions 28, 30 are connected to each other via a tension spring 32.

At a lower end portion of the return lever 18 in Figure 1, a driving pin 34 is arranged, against which the clamping levers 28, 30 in the illustrated basic position of the actuating piston 2. In the control piston 10, a pin 36 is provided, on which the clamping levers 28, 30 abut in the illustrated basic position.

Up to this point, the basic structure of the drive unit 1 corresponds to that which is explained in the above-described prior art DE 195 40 654 C1 and DE 10 2008 048 507 A1, so that reference can be made to these documents for further details. In this prior art, the two clamping levers 28, 30 produced by investment casting - the associated disadvantages are explained above. As explained in more detail below, according to the invention, the two clamping levers 28, 30 are made by stamping, the component geometry was adapted to this manufacturing process. Details will be explained with reference to Figures 2 to 9. By adjusting the control piston 10, a control pressure difference in the two control chambers 6, 8 adjusted, so that the Stellkoben 2 is adjusted from its illustrated home position and pivots the swash plate accordingly. The displacement of the control piston 10 is transmitted via the pin 36 to one of the tension levers, for example the tension lever 24, so that it lifts off from the driving pin 34 against the force of the tension spring 32. By the force of the tension spring 32 thus the control piston 10 is acted upon by a restoring force by which the control piston 10 is reset in Stromlosschalt the electromagnet or setting a force acting on the control piston 10 control difference in the range of zero. By adjusting the control piston 10, the actuating piston 2 is acted upon by the said control pressure difference, so that it is adjusted while the reset lever 18 is pivoted. The control position is reached when the force applied to the control piston 10 actuating force is equal to the spring force acting in the return direction.

Figure 2 shows a three-dimensional representation of the two clamping levers 24, 26, which have an identical structure. Each clamping lever 24, 26 has a lever eye 38, 38 'on which a lever shaft 40, 40' is arranged. The lever eyes 38, 38 'are designed such that, when the two lever eyes 38, 38' are offset by 180 °, the respective lever shafts 40, 40 'are arranged in one plane. According to the illustration in FIG. 2, the lever shafts 40, 40 'after the respective lever eye 38, 38' initially extend essentially parallel to one another in the radial direction. At a distance from the respective lever eye 38, 38 ', the lever shafts 40, 40' angled approximately Y-shaped. At the end portions of the lever shafts 40, 40 'are each hook-shaped constrictions 42, 42' are formed, on which the tension spring 32 can be mounted.

FIG. 3 shows a plan view of the two tensioning levers 24, 26. It can be clearly seen in this illustration that the two lever eyes 38, 38 'are congruent with one another. As shown in Figure 1, these lever eyes 38, 38 'are penetrated by the axis 22, which is arranged on an eccentric pin inserted in the housing 20. To the lever eye 38, 38 '(the latter in Figure 3 is not visible), a tangential leg 44, 44' of each clamping lever 24, 26 connects. At the mutually facing side surfaces of the tangential legs 44, 44 'is in each case a recess formed, which complement each other in the illustrated basic position to a slot 45 through which the pin 36 of the control piston 10 extends. As explained, each lever shaft 40, 40 'following the respective tangential leg 44, 44' angled to an angle leg 46, 46 ', wherein at the end portions in each case the hook-shaped constrictions 42, 42' are provided for suspending the tension spring 32. In the transition region between the tangential legs 44, 44 'to the angle legs 46, 46' are spaced contact surfaces 48, 48 'is formed, which bear in the illustrated basic position on the driving pin 34 of the reset lever 18.

FIG. 4 shows the tensioning lever 26 in a detail view. Accordingly, the lever eye 38 is encompassed by a lever hub 50, to which a tangent leg 44 is attached via a cascade stage 52, which will be explained in more detail below. This Tangentialschenkel 44 extends approximately tangentially to the lever eye 38. In the illustration of Figure 4 can be seen also the recess 54, which complements the slot 45 together with the recess of the other clamping lever.

The tangential leg 44 merges into the angle leg 46, wherein the contact surface 48 is provided for the driving pin 34 in the transition region. The constriction 42 is formed at the end portion of the angle leg 46, which is angled approximately in the tangential direction, the structure of which is explained with reference to the detail views according to FIGS. 5 to 7.

Figure 5 shows an enlarged view of the end portion of the angle leg 46 with the hook-shaped constriction 42. In the transition region to the constriction 42 an inclined surface 56 is formed, which extends in the representation of Figure 5 perpendicular to the plane. The angle of attack of the inclined surface 56 to the horizontal (horizontally in Figure 5) corresponds approximately to 30 °. This inclined surface 56 is also visible in the side view of the clamping lever 26 in FIG. It can also be seen from this illustration that the end section is stepped back on both sides approximately in the middle region of the inclined surface 56, so that the width b of the constriction 42 is slightly smaller than the width B of the angle leg 46 and also of the tangential leg 44. From this downgrading from the width B to the width b, the end portion forming the constriction 42 tapers towards the viewer in FIG. 8 in a wedge-shaped or roof-shaped manner, with a vertex 58 then also extending into the oblique surface 56.

Figure 6 shows a section along the line AA in Figure 5. It can be seen from this the wedge-shaped convergence of the constriction 42 toward the apex 58. Furthermore visible is a flattening 60 of the apex 58 in the deepest region, which in the view of Figure 5 is a groove formed. Along this flattening 60 or groove, the end portion of the spring 32 abuts.

FIG. 7 shows a section along the line B-B in FIG. 5. It can be seen from this illustration that the constriction 42 tapers in a wedge shape toward the vertex 58 in this area as well. Following the constriction 58, an end face 62 of the angled limb 46 is rounded, wherein the wedge-shaped taper of the end section extends into the end face 62 (see FIG. 8). In the transition region of the end face 62 to the lower side surface 64 of the angle leg 46, a small step 66 is formed on both sides as shown in FIG. 5, over which the side surfaces (visible in FIG. 5) of the angle leg 46 are slightly reset.

By the inclined surface 56 a flattened transition from the angle leg 46 is formed in the region of the constriction 42, which ensures during embossing that in this area no defects, such as cracks and distortions can arise. In the conventional geometry of the clamping lever such defects would not have been ruled out.

The connection region of the tangential leg 44 via the cascade stage 52 to the lever eye 38 is also optimized with regard to stamping. According to the illustrations in Figure 4 (top view) and Figure 8 (side view) of the clamping lever 26 is in the transition region of the lever eye 38 encompassing lever hub 50th to the tangential leg 44, first an approximately tangential direction tangential step 68 is formed, which is approximately trapezoidal or triangular in plan view according to FIG. As can be seen from the side view according to FIG. 8, this tangential step 68 has a comparatively high height H. Following the tangential step 68, a transverse step 70 is formed whose height h is significantly less than the height H of the tangential step 68. The transverse step runs transversely to the longitudinal axis of the lever shaft in the region of the tangential leg 44. In the plan view according to FIG. 4, the end plane of the lever hub 50 is cascade-shaped via the tangential step 68 and the transverse step 70 to the large plane of the tangential leg 44. This cascade-shaped gradation allows a large height offset between the end face of the lever hub 50 and the large surface of the lever shaft 40, so that also by this configuration of the clamping lever 24, 26 punching embossing is made possible with a low reject rate.

Finally, FIG. 9 shows a bottom view of the tensioning lever 26. It can be seen from this figure and FIG. 8 that the height offset V between the lower end face (visible in FIG. 9) of the lever hub 50 and the large surface 72 of the lever shaft 40 is significantly less than the height offset H. + h on the other side, wherein the visible in Figure 9 end face of the lever eye 38 relative to the large surface 72 of the lever shaft 40 is reset. This geometry makes it possible to arrange the two clamping levers 24, 26 offset by 180 ° (see FIG. 3) and, in the area of the lever hubs 50, to place them in cross-section on the axis 22 so that the Y-axis shown in FIG. Structure yields.

The tensioning lever arrangement according to the invention and a control unit designed with such a tensioning lever arrangement on a hydraulic machine, preferably an axial piston machine, are characterized by extremely simple manufacturability with a low reject rate. The stamping or fine blanking embossing used makes it possible to produce the clamping levers without reworking the components with the utmost precision.

Disclosed are a clamping lever arrangement, a method for producing a clamping lever of such a clamping lever arrangement and a driving device of a Hydraulic machine with such a clamping lever assembly, wherein the clamping levers are manufactured in fine blanking embossing technique.

Claims

claims

1. Tension lever assembly of a device for position feedback of a control piston for adjusting a delivery / absorption volume of a hydraulic machine, wherein a clamping lever (24, 26) with a lever eye (38) is pivotally mounted, which is connected to a lever shaft (40) and at least one in Direction of

Pivot axis opposite the lever shaft (40) protrudes, wherein the lever shaft (40) at its end portion a constriction (42) for suspending a tension spring (32), characterized in that the clamping lever (24, 26) is made in fine blanking embossing technique.

2. Tension lever arrangement according to claim 1, with two clamping levers (24, 26) which rotate through 180 ° form an approximately Y-shaped clamping lever pair, between the end portions of the tension spring (32) is arranged.

3. Tension lever arrangement according to claim 1 or 2, wherein the lever eye (38) is stepwise stepped back to the lever shaft (40).

4. Tension lever arrangement according to claim 3, wherein the downgrading via a cascade stage (52) with a tangential stage (68) and a lever shaft (40) offset at an acute angle to the tangential stage (68) arranged transverse step (70) is formed, which is approximately transversely to the lever longitudinal axis (22).

5. Tension lever arrangement according to claim 4, wherein by the

Tangentialstufe (68) a greater height offset (H) than by the transverse step (70) is formed.

6. Tension lever arrangement according to one of the preceding claims, wherein the lever shaft (40) to the constriction (42) is bevelled over an inclined surface (56).

7. Tension lever assembly according to claim 6, wherein the inclination of the inclined surface (56) is less than 45 °, preferably about 30 °.

8. Tension lever arrangement according to one of the preceding claims, wherein the constriction (42) to a vertex (58) is tapered.

9. Tension lever arrangement according to one of the claims 6, 7 or 8, wherein the inclined surface (56) in extension of the apex (58) is tapered roof-shaped.

10. Tension lever arrangement according to one of the preceding claims, wherein the lever eye (38) on the other hand in the pivot axis direction relative to the lever shaft (40) is reset.

11. tension lever assembly according to claim 10, wherein the height offset (V) via a step (66).

12. A method for producing a clamping lever (24, 26) of a

Tension lever arrangement according to one of the preceding claims, wherein this is produced by fine blanking embossing.

13. Control device of a hydraulic machine, with a clamping lever arrangement according to one of the claims 1 to 1 1 or prepared according to claim 12.

14. Control device according to claim 13, wherein the hydraulic machine is an axial piston machine.