DE8717463U1 - Control device for reversible hydrostatic axial or radial piston machines - Google Patents

Description

G, Düsterloh GmbH, Häuptstraße 70, 4322 Sprockhövel 1

Control device for reversible hydrostatic _t \ _lt axial or radial piston machines \, _M

The invention relates to a control device for
reversible hydrostatic axial or radial piston machines according to the features in the preamble of claim 1. ; ';

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DE-PS 18 01 541, in particular Figure 2, provides a
Control device is known in which only a single ring is provided between the inner ring and the outer ring of the control ring.
Sealing element provided 1st, in axial direction supports
This sealing element extends over its entire radial height
on the one hand on the inner ring and on the other hand on the outer ring. This arrangement can result in
Reversal of the direction of rotation of the machine, i.e. when the load is directed from the interior to the exterior or
Conversely, the sealing element in axial direction
has to travel a distance until it reaches the perfect axial pressing position again after the full pressure build-up. During this indifferent phase, however, the
Danger that the inner ring can lift off the control surface of the cylinder block and an undesirable flow of the working medium can occur there. If the contact pressure is too low
There is even the possibility that a satisfactory contact of the inner ring with the control surface of the cylinder block is generally the aim.

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Another problem in the known case is that at high working pressures, the circumferential stepped gap between the inner ring and the outer ring can only be made very narrow due to the elastic thickness element. As a result, pressure can only build up slowly within the gap. If the gap is made too wide, there is a risk that the thickness element will extrude into the gap.

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In order to eliminate the disadvantageous properties of the design described above, it has been proposed in the scope of DE-PS 28 55 566 to provide two sealing elements between the inner ring and the outer ring. The annular space formed between the sealing elements is deliberately _put under _pressure so that the sealing elements always ^point in the direction of the front.

surfaces of the control ring parts. ! ₍ !

This design, which has proven itself in practice, requires a valve arrangement that ensures that the annular space between the two sealing elements is always subjected to the higher pressure in the outer space or in the inner space to ensure perfect contact. However, such a valve arrangement in the control device leads to difficulties in accommodating smaller machine units. Furthermore, the valve arrangement is subject to an unavoidable natural inertia, which not only makes it susceptible to faults but also results in time delays during the switching process. It is therefore not suitable for use with high-frequency servo drives in which the direction of rotation changes in the order of 50 to 100 hertz.

The invention is based on the task of improving the control device described in the preamble of claim 1 so that it can be used even with small-powered machine inputs.

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units and high-frequency servo drives can be used successfully «

According to the invention, the solution to this problem consists in the features listed in the characterizing part of claim 1.

The special feature of the design according to the invention is the creation of a differential piston effect between the sealing elements. Since the remaining protective air sealing elements have different inner and outer diameters '',, different sized surfaces with ,',,, _result .

The result is that even when the pressure is changed from the interior to the exterior and vice versa _, there is always an excess contact pressure. On the one hand, this arrangement avoids the sealing elements having to travel long distances before they can exert their effect. Their function can thus be ensured over a longer period of use. On the other hand, no additional valve arrangements are required to ensure the necessary contact pressure, especially during the switching process. This means that no additional holes and channels have to be accommodated in the control device and the invention can therefore be used to advantage even with very small units in terms of performance. In addition, there is the advantage that the control device according to the invention is also suitable for high-frequency servo drives with a range of 50 to 100 Hertz. In this context, it should also be emphasized that the differential area of the quasi-existent differential piston only needs to be of a small size in order to ensure that during the During the changeover phases, there is no lifting effect of the contact surfaces of the control ring parts from the counter surfaces and therefore no pressure collapse needs to be feared. The valve arrangements are also always susceptible to faults.

«*«»:£ fcedi. af te embodiment of the basic idea according to the invention consists in the features of claim 2. Here, the support surfaces are formed on high-strength rings, e.g. steel rings, which rest on shoulders of the inner ring or the outer ring. Instead of steel, other suitable materials can of course also be used.

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the features of claim 3. There, on the one hand, ^a ring collar is used as a one-piece component of the inner ring or the outer ring to form a support surface for a sealing element. On the other hand, the support surface for the further sealing element is formed from a high-strength ring, for example a steel ring. A split

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I high-strength ring is, however, only necessary if

1 the ring collar is formed on the inner ring to facilitate assembly

y ge to be able to be pushed over the ring collar.

I The features of claim 4 include the advantageous

F Property that due to this only one-sided sealing

ij Grooved rings in case of leakage in the annular space between the grooves

■ rings no pressure can build up. Should a grsring-

If a pressure is created in this annular space, this

g immediately over the elastic sealing lips of the

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I Relieve the grooved rings towards the respective low-pressure side,

J without this leading to a displacement of the sealing elements

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^! . The wave springs characterized in claim 5 serve to

&bull; when the machine is depressurized, the control ring parts

I against the corresponding counter surfaces. Gl^ieä

At the same time, the wave springs take over the task of sealing

1 element positioning end stop.

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The invention is explained in more detail below using embodiments shown in the drawings. Show:

Figure 1 shows a longitudinal section through the control device of a hydraulically actuated radial piston motor ;

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Figure 2 shows an enlarged view of the sealing area '< between the inner ring and the outer ring of the '"' control device of Figure 1 and '

Figure 3 also shows in enlarged view the seal

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area between the inner ring and the outer*- E

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ring of the control device of Figure 1 according to ·,,',· f another embodiment.

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In Figure 1, 1 designates the housing of a radial piston engine 2, which is shown in more detail only with regard to the control device. 3 is the cylinder block 6 f.

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The channels 5 leading to the cylinders 4 of the radial piston motor ² open into a control surface 7 on the front side of the cylinder block 6. This has a central bore 8 through which the machine shaft 3 passes. An eccentric disk 10 is mounted on the end 9 of the machine shaft 3 in a rotationally fixed manner. The eccentric disk 10 lies directly on the control surface 7 on the one hand and indirectly on a support surface 12 of an insert 13 of the machine housing 1 with the elastic interposition of a pressure bush 11 on the other. The elasticity between the eccentric disk 10 and the pressure bush 11 is brought about by a spring 14. I

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An inlet channel 15 and an outlet channel 16 for the working medium are provided in the insert piece 13. Depending on the direction of rotation, the function of these channels 15 and 16 changes.

The eccentric disk 10, which is provided with at least one opening 17, rests circumferentially with the incorporation of a roller bearing 18 on an inner ring 10 of a control ring 20, which slides with its end face 21 on the control surface 7. The inner ring 19 is overlapped by an outer ring 22 of the control ring ²⁰ , which slides with an end face 23 on the support surface 12 of the insert 13. The sliding contact of the inner ring 19 or the outer ring 22 on the control surface 7 or on the support surface 12 is on the one hand '

by wave springs 24 in the pressureless state of the motor 2 and ¹ on the other hand by the pressure of the working medium in the outer chamber 25 or in the inner chamber 26 of the control device.

When the engine 2 is operating, the control ring 20 consisting of the inner ring 19 and the outer ring 22 is displaced by the eccentric disk 10 connected to the machine shaft 3 over the control surface 7 and the support surface 12 in such a way that the channels 5 leading to the cylinders 4 are alternately connected to the inner space 26 or to the outer space 25, which in turn are connected to the channels 15, 16 in the insert piece 13 and to which higher or lower pressure is assigned.

As can be seen in more detail in Figure 2, grooved rings 29, 30 with sealing lips 31 are embedded in recesses 27, 28 of the inner ring 19 and the outer ring 22. The grooved rings 29, 30 are supported with the mutually facing end faces 32, 33 on steel rings 34, 35, the radial height of which corresponds to the radial height of the grooved rings 29, 30. The radially inward and radially outward directed circumferential areas 36, 37 of the steel rings 35/34 reach the opposite circumferential surfaces 38, 39 of the inner ring 19 and the outer ring 22, respectively.

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of the outer ring 22 for sliding contact. The circumferentially closed steel rings 34, 35 are supported on shoulders 40, 41 of the control ring parts 19, 22 which are located opposite one another with a radial distance in relation to their circumferential surfaces 38, 39.

The arrangement described above creates differential pistons 34, 35 which, in conjunction with the grooved rings 29, 30, ensure that an excess force is always present when the external space 25 and the internal space 26 are pressurized with working medium, which does not cause the inner ring 19 to lift off the control surface 7 or the outer ring 22 from the support surface 12 during the switching phase, thus preventing a pressure collapse.

The wave springs 14 also have the task of positioning the grooved rings 29, 30. They therefore serve as an end stop.

Figure 3 shows an embodiment in which the grooved ring 29 embedded in the inner ring 19 is supported on an annular collar 42 of the inner ring 19. The grooved ring 30 embedded in the outer ring 22, on the other hand, is supported on a steel ring 43, which rests on a shoulder 44 of the outer ring 22. In this case, it is necessary to make the steel ring 43 split in order to be able to slide it over the annular collar 44 during assembly. Otherwise, the embodiment in Figure 3 corresponds to that in Figure 2 or Figure 1.

The control device is enclosed by a spacer body 45, which is integrated between the cylinder block 6 and the insert piece 13 and is sealed against these parts 6, 13 by sealing rings 46. The cylinder block 6, the spacer body 45 and the insert piece 13 are held together by tie rods 47.

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133/33622

XR/Mo

Reference symbol list

1 Housing &ngr;. 2 2 Radial piston engine 3 Machine shaft 4 Cylinder v. 2 5 Channels in 1 6 Cylinder block 7 Control surface 8th Drilling in 7 9 End of 3 10 Eccentric disc 11 Pressure bushing 12 Support surface at 13 13 Insert 14 Spring f. 11 15 Inlet channel 16 Drainage channel 17 Breakthroughs in 10 18 roller bearing 19 Inner ring 20 Controlling 21 Front face of 19 22 Outer ring 23 Front face v. 22 24 Wave spring 25 Outdoor space 26 inner space 27 Recess in 19 28 Recess in 22 29 Grooved ring 30 Grooved ring 31 Sealing lips on 29, 3 32 Front side of 29 33 Front side of 30 34 Steel ring 35 Steel ring 36 Circumference range v. 35 37 Scope of 34 33 Circumferential area v. 19 39 Circumferential area v. 22 40 Shoulder f. 34 41 Schlter f. 35 42 Ring collar 43 Steel ring 44 shoulder 45 Spacer body 46 Sealing rings 47 Tie rod

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Claims (1)

lilt 1 I 1, Control device for reversible hydrostatic axial or radial piston machines with a control disk with flow openings and flat end faces, which consists of an eccentric disk connected to the shaft in a rotationally fixed manner and a control ring which is freely rotatably mounted on the outer circumference of the eccentric disk and is formed from an inner and an outer ring, the parts of which are guided into one another in a telescopically sealing manner by incorporating two sealing elements embedded in recesses in the inner and outer rings and having different inner and outer diameters, forming an annular space between them, and can be hydraulically pressed apart axially with the aid of spring force, one of the control ring parts resting with its free end face sealingly against a support surface fixed to the housing, while the opposite free end face of the other control ring part can be pressed against the control surface of the cylinder block provided with control openings, characterized in that the Il * I I I I I ti * II * * I ! 34) to cfc t^fe ), fei &phgr; ^tyfai* 361 _B Wöp d ■ Te.o ₀ r. S.ühlmflfifipa Cdrfimöfzbonk AQ., Boahum. No. 3 &bgr;&Ogr;4 7Ö2 ■ Poatalröl<-,rHo Eäsön ?4 4t^ä\ ■ Please provide act no. and date ohfiobon V'Vf · i ·"* &iacgr;··*·Pi'i:"&iacgr;*&iacgr;:": facing end faces (32, 33) of the sealing elements (29, 30) are supported over their entire radial height on high-strength surfaces (34, 35; 42, 43) which are designed to form a force- in the direction of the end face (7) of the cylinder. blocks (6) and the front face (7) opposite - differential piston acting on the housing-fixed support surface (12) effect with their radially inward or outward directed circumferential areas (36, 37) slidingly abut the respective opposite circumferential surface (38, 39) of the inner ring (19) or the outer ring (22). '"·, 2« Control device according to claim 1, characterized in that jj indicates that the surfaces (34, 35) are at ge-!J ₁ j closed high-strength rings are provided, which on shoulders (40, 41) of the circumferential surfaces (38, 39) which are opposite one another at a radial distance from one another;' support the control ring parts (19, 22). 3. Control device according to claim !, characterized in that the surfaces (42, 32) are on the one hand on one of the inner ring (19) or the outer ring (22) ;. one-piece Rir-j collar and on the other hand on a split high-strength ring is provided which is supported on a shoulder (44) of the outer ring (22) or the inner ring (19). 4. Control device according to one of claims 1 to 3, characterized in that the sealing elements are formed by grooved rings (29, 30) with their sealing lips (31) facing away from one another. 5. Control device according to one of claims 1 to 4, d a - ₍ characterized in that the control ring" parts (19, 22) can be pushed apart by springs (24)« 4 4
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