EP0585609B1 - Hydrostatic machine with axial thrust balancing - Google Patents

Abstract

The invention relates to a hydrostatic machine with a cylinder assembly which is arranged on the shaft and has radial bores with displacer elements (piston and sliding block) sliding on the inside of a cam ring, the bores being connected to delivery passages. The invention is characterised in that the radial cylinder assembly comprises two rotors mounted a distance apart, the bores of which have intercommunicating timing ports, in that an intermediate casing wall is provided between the two rotors, this wall having control discs with passages and connecting passages for the respectively associated passages, and in that the cam rings of the two rotors are rigidly connected to one another by a bearing shaft and the shaft and the bearing shaft are each supported by a bearing in the intermediate wall. <IMAGE>

Description

The present invention relates to a hydrostatic machine according to the preamble of claim 1.

Such a machine has become known from US-A-3 044 412. The two rotors of that machine are designed as double rotors. On the rotor shaft there is a flange that is fixed to the shaft between the two rotors.

With this machine there is a risk that pulsating forces arise from the hydrostatic load which have to be guided over the outer surfaces of the machine.

A single-flow so-called side-loaded hydrostatic machine is known from DE-OS 39 05 936. Measures and means are provided to absorb or compensate for the axial thrust forces acting on the cylinder star (rotor) via the (drive) shaft. However, it has been shown that the axial forces are disadvantageously large and that the pulsating radial forces flow back over the outer surface of the machine to the bearing points, with undesirable loud noises being produced. Another problem is that the bearing points of the central shaft of the previously mentioned machine have to be aligned very precisely, which necessitates an increased production outlay.

The object on which the present invention is based is to provide a hydrostatic machine of the generic type in which no pulsating forces arising from the hydrostatic load have to be conducted over the outer surfaces of the machine and in which the alignment of the housing cover, which is technically complex to produce, is superfluous .

This object is achieved by the features specified in the characterizing part of patent claim 1.

The particular advantages of this configuration or construction lie in the fact that both the axial forces and the radial forces are absorbed inside the pump and therefore cannot cause noise excitation via the outer surface.

In addition, the simple mounting of the cylinder star and the cam ring is very advantageous for production.

Special refinements and developments of the hydrostatic machine specified in claim 1 are the subject of the dependent claims.

Fig. 1

einen Längsschnitt durch eine hydrostatische Maschine;

Fig. 2

einen Querschnitt durch die hydrostatische Maschine gemäß Fig. 1 längs der Schnittlinie II-II;

Fig. 3

den Längsschnitt durch die hydrostatische Maschine gemäß Fig. 1 mit Angabe der axialen und radialen Kraftflüsse innerhalb der hydrostatischen Maschine;

Fig. 4

einen Querschnitt durch die hydrostatische Maschine gemäß Fig. 1 längs der Schnittlinie III-III.

The details of the hydrostatic machine according to the invention are explained in more detail below with reference to the drawing. This shows in

Fig. 1

a longitudinal section through a hydrostatic machine;

Fig. 2

a cross section through the hydrostatic machine according to Figure 1 along the section line II-II.

Fig. 3

the longitudinal section through the hydrostatic machine according to FIG 1 with indication of the axial and radial force flows within the hydrostatic machine.

Fig. 4

a cross section through the hydrostatic machine according to FIG. 1 along the section line III-III.

The radial piston machine representing the hydrostatic machine has a housing 1 with two interior spaces 6, 7 separated by an intermediate floor 5. The interiors 6, 7 are closed from both sides via a housing cover 3. In each of the two subspaces (interior spaces) 6, 7, a cam ring 8, 9 is mounted, which both are connected to one another via at least one connecting shaft 11 and via a bearing shaft 10 and to the intermediate floor 5 via bearings 36.

On the inside 12, 13 of the lifting rings 8, 9, in a manner known per se, the displacement elements serving the function or use as a hydrostatic machine or as a radial piston machine, which consist of the functional connection of a sliding block or sliding block 14 and an articulated (displacement) block Piston 15 exist. These pistons 15 are each arranged in radial bores 16, 17 of one of the rotors 18, 19 forming the cylindrical star, which in turn are coupled in a rotationally fixed and axially fixed manner to a shaft 20 driven by a drive connector 26 mounted in a bearing 4.

The configuration described above corresponds - apart from the fact that nothing has been said about the flow rate or the pumping function - to the state of the art insofar as the rotors 18, 19 are known per se. The special configuration, however, consists in the fact that the hydrostatic machine does not start from one rotor 18, 19, but from two, which act synchronously with one another as a motor or pump unit (which ultimately achieves twice the delivery capacity with radially identical dimensions) and that Drive shaft is mounted between the rotors 18, 19 in connection with the cam ring bearing located in the intermediate floor 5 between the cam rings 8, 9.

With regard to their function as a pump element, the two rotors 18, 19 are coupled or functionally connected to one another in a coordinated manner as follows: In the radial bores 16, 17 of the rotors 18, 19, axial lateral control slots face one another 21, 22 are provided, through which the bores 16, 17 are open to the intermediate floor 5. These control slots 21, 22 in turn correspond to kidney-shaped channels 23, 24 incorporated in control disks (axial disks) 25, 26 (cf. FIG. 4). The control disks 25, 26 are inserted in corresponding recesses on both sides of the intermediate base 5. In the intermediate floor 5 itself, corresponding to the control slots 21, 22 and the kidney-shaped channels 23, 24, transverse connecting channels 27, 28 are incorporated so that both rotors 18, 19 are connected to one another via their displacement elements - and together as a pump or hydrostatic machine able to work; this creates a double-flow hydrostatic machine or radial piston machine, the connecting channels 27, 28 forming the inlet and outlet channels and accordingly being open to the outside.

The axial thrust resulting from the (lateral) pressurization of the pistons 15 and the control slots 21, 22 becomes due to the equally large axial channels 23, 24 in the control disks 25, 26 and these channels 23, 24 in the gaps between the rotors 18 , 19 and the control discs 25, 26 surrounding pressure fields 29, 30 thus compensated for by an oppositely directed effect of the hydrostatic forces. The frictional connection B between the rotors 18, 19 via the shaft 20 thus avoids any axial application of force to the housing 1.

With appropriate storage or support of the shaft 20 relative to the intermediate floor 5 and the support of the cam rings 8, 9 via the bearing shaft (pivot shaft) 10 on the intermediate floor 5, a simple mounting can also be represented, as shown in FIG. 3, the radial frictional connections A and C inside the pump leads.

With regard to the overall structural configuration, it should also be noted - compare FIG. 4 - the two cam rings 8, 9 are positioned together via an adjusting device consisting of an adjusting piston 31 and a counter-piston 32. This adjustment device is mounted or attached to the intermediate floor 5 and is effective. In the intermediate floor 5 there are - as mentioned - the connecting channels 27, 28, i.e. the inlet-side low-pressure duct and the outlet-side high-pressure duct are incorporated.

As already mentioned, the rotors 18, 19 are fixed in a rotationally fixed and axially fixed manner on the shaft 20. As shown, both rotors can be removed from the shaft 20 (see clamping nut 37); the shaft 20 is driven via a coupling sleeve 40 from the drive socket 2.

In the construction described above and shown in the drawing, a collar 33, 34 is provided on the shaft 20 for each rotor 18, 19. During assembly, the rotors 18, 19 are pressed against these collars 33 and 34 by means of clamping elements 37. The distance between the bundles 33, 34 is slightly larger than the sum of the thickness of the intermediate floor 5 and the thickness of the control discs 25, 26.

In principle, the rotors 18, 19 can also be fixed on the shaft 20 in such a way that one rotor is formed in one piece with the shaft 20, while the second rotor is fixed via a clamping nut.

In a special embodiment, it is also possible to rotate the two rotors 18, 19 relative to one another, for example by one to fix half division of the radially arranged displacement elements.

In summary, the following should be noted again:
The axial fixation of the two rotors 18, 19 on the shaft 20 ensures that the axial forces do not have to be supported on the housing covers 3. The mounting of the drive shaft 20 via bearings 35 in the intermediate floor 5, as well as the mounting of the lifting rings 8, 9 in the same intermediate floor 5 enable the frictional connections A, B and C, all of which have an effect inside the machine. The gap required for the rotors 18, 19 to run reliably relative to the control disks (axial disks) 25, 26 should be kept as small as possible because of the tightness which depends on them. This is finally achieved by inserting elastic seals 38, 39, for example O-rings, in the control disks 25, 26 on the sides facing the intermediate base 5, which seals by limiting the pressure fields 29, 30 against the respective adjacent rotor 18 , 19 generate a force that is determined by design slightly larger than that generated by the pressure field distributed over the metallic seal on the rotor side of the control disks 25, 26. As a result, the gap between the rotors 18, 19 and the control disks 25, 26 is kept very small.

Claims (2)

1. Hydrostatic machine with a cylinder star disposed on the shaft (20) fixed non-rotatably and axially which has a plurality of radial bores (16, 17) with displacer elements (15, 14) sliding on the inside of a lift ring (8, 9), whereby the bores (16, 17) are connected to transporting channels issuing from the sides of the cylinder star to control the amount of pressure medium conveyed by means of control slots (21, 22), whereby the cylindrical star comprises two rotors (18, 19) mounted at a distance from one another, the bores (16, 17) of which have control slots (21, 22) communicating with one another, in particular opposite one another,
   whereby a casing false-floor (5) is provided between the two rotors (18, 19) which has control discs (25, 26) opposite the rotors (18, 19) with channels (23, 24) corresponding with the control slots (21, 22) and connecting channels serving as transporting channels (27, 28) for the channels (23, 24) connected together,
   characterised in that
   the lift rings (8, 9) of both rotors (18, 19) are rigidly connected to each other by a bearing shaft (10) and the shaft (20) and the bearing shaft (10) are both mounted on a bearing (35, 36) in the false floor (5).
2. Hydrostatic machine according to claim 1
   characterised in that
   for each rotor (18, 19) a flange (33, 34) is provided on the shaft (20) against which the rotors (18, 19) are pressed by means of clamping elements (37) and the distance of which is somewhat greater than the sum of the thickness of the false floor (5) and the control discs (25, 26).

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