EP0469135B1 - Gear pump or motor - Google Patents

Abstract

The filler (8) of a gear pump (1) or motor, which is fitted in an intermediate space (4) formed by an internal geared wheel (2) and a pinion (3), has a sickle-shaped seal (7) to which are secured laterally downwardly directed bearing pins (6), whereby the filler (8) is in one piece and/or is formed in two pieces by a separating gap (14) extending from the high-pressure area (13) into the low-pressure chamber (11).

Description

The invention relates to a gear pump or motor according to the preamble of claim 1.

In order to achieve a favorable volumetric efficiency, the leakage currents of the medium to be conducted between the high-pressure and low-pressure space are to be kept as low as possible in the present subject.
The sealing between the high-pressure and low-pressure space places high demands, among other things, on the sealing element - also called a filler piece - which, on the one hand, must be able to seal the gap entering at least one side facing the toothing and to compensate for the loads of the acting forces take. In addition, the sealing element on the adjacent parts should be distinguished by advantageous sliding properties.

From DE-PS 15'53'027 an internal gear pump has become known, in which the sealing element is movably mounted on both sides in a sliding block arranged in axial plates by means of a penetrating bolt. In this construction, it is essential that the resultant of the hydraulic forces acting on the filler piece runs through the geometric axis of the filler piece bolt.

On the basis of DE-PS 29'42'417 an internal gear machine is known which has a semi-crescent shaped filler which is divided along an approximately circumferentially extending partial surface, the filler parts of which are supported with support surfaces on an axially penetrating the space between the ring gear and pinion, rotatable about its longitudinal axis Support the stored filler pin. For this purpose, a flat support surface is provided on the filler pin and the filler has several parts, the assembly of which requires appropriate care and special attention.

To prevent the filler from becoming wedged due to the friction with the toothing between the pinion and the ring gear when starting up without pressure, in particular an internal gear machine, According to DE-OS 16'53'818, an additional pin penetrating the filler in the axial direction is used.

These designs contain the common disadvantage that the number of parting lines and friction surfaces increases due to the sealing and holding functions distributed over several parts and thus leads to high stresses.

A rotary lobe machine, pump or a motor is known from DE-B-1'280'056 (Robert Bosch). This has two internal gears, with pressure plates pressed on both sides of the same sealingly against the gear side surfaces. On the rear sides facing away from the gearwheels there is a pressure field delimited by a seal, which can be acted upon by liquid under pressure. Viewed in cross-sections through the machine, this lies eccentrically to the gear axis of rotation or shifted to one side with respect to the internally toothed outer wheel. This rotary piston machine, which is provided with two connections serving as pressure or low-pressure channel, is designed in such a way that the contact pressure of the pressure plates on the gear side surfaces is at least almost uniform in both directions of rotation of the gear wheels.

The size and position of the pressure fields can best counteract the axial forces occurring on the gear side surfaces with a simple shape. This is achieved in that the pressure field behind the pressure plate located on one side of the gearwheels, when viewed in corresponding cross-sectional planes, is arranged opposite to eccentric with respect to the gearwheel axes of rotation. It is thus shifted in relation to the outer wheel in the opposite direction to the pressure field behind the pressure plate located on the other side of the gear wheels. The first-mentioned pressure field is connected to one of the connections (pressure or low-pressure channels) and the second-mentioned pressure field to the other connection of the Machine. These connections can be used alternately as inlets or outlets, which means that the machine can be used reversibly in its direction of rotation.

From DE-A-26'41'278 (Voith) an internal gear pump with a driven externally toothed pinion is known. An internally toothed ring gear meshes with the pinion, which is mounted in a housing or in a bearing shell connected to it in a stationary manner. With a sealing surface on each of the pinion and the ring gear, there is a semi-crescent-shaped filler which, together with these, forms the circumferential limit of a pressure chamber. In this case, automatic radial wear compensation is essentially only achieved during the running-in process, with any compensation option being dispensed with to simplify production, and a one-piece filler piece being retained. This is achieved in that the one-piece filler has an interior. This extends essentially over the full length of the filler parallel to the axes of rotation of the gears through the filler. The interior is in line connection with the pressure chamber and its cross-section is dimensioned such that the filler elastically expands under the liquid pressure.

The invention is therefore based on the object of designing the filler piece of a gear pump or a geared motor of the type described at the outset in such a way that the seal between the high-pressure and low-pressure spaces is considerably improved and the assembly of the filler piece is simplified and the functional reliability is increased and less wear and tear - for example by Reduction of the support surfaces - can be determined.

According to the invention, this object is achieved in that the bearing journal (s) are arranged at least approximately at the end of the sealing body facing the low-pressure chamber and in that the separating gap extends at least approximately to the end of the filling piece facing the low-pressure chamber.

As a result, the wear resistance and functional reliability of the filler can be improved.

A preferred embodiment of the filler has a one-piece filler formed from the sealing body and bearing journal. The installation of the filler in the laterally adjacent parts of the gear pump or the gear motor can be done in the simplest way.

The arrangement of the bearing journals on the end of the sealing body facing the low-pressure chamber permits optimal use of the sealing surfaces on the tooth tips, in that the outer sides of the sealing body extend over the entire length of the filler in the intermediate space.

To improve the adaptability of the sealing body to the tooth tips, the filler can be provided with a separating gap which extends in the circumferential direction from the high-pressure region and forms an inner and an outer leg. As a result, a significantly improved sealing effect on the tooth tips can be produced, in particular, by the increased elasticity of the opened sealing body.

The fact that the sealing body and bearing journal together form a filler piece makes it possible, among other things, for the separating gap to be designed at least approximately over the entire length of the filler piece.
This means that the inner and outer legs are connected to each other at the end of the filling piece facing the low-pressure chamber.

With such a design, it is expedient if the separating gap has a cavity at the end facing the low-pressure chamber, in order to thereby largely avoid the notch effect occurring in the sealing body as a result of the separating gap and to increase the elasticity of the inner and outer legs.

In this context, it proves to be excellent that the shape of the cavity increases steadily towards the low-pressure space.

Alternatively, for the same purpose, the cavity can have partition walls which are evenly spaced approximately in the circumferential direction, in order to be able to provide the cavity as a core during the manufacture of the filler blank by casting.

Depending on the circumstances or requirements, the cavity could be tapered towards the low-pressure chamber, and thereby have an advantageous effect on the strength, wear and elasticity of the filler.

To achieve optimum strength values, it is advantageous if the separating gap is arranged at least approximately in the center of the sealing body at least in the region of the bearing journal. This also applies if the separation gap ends before the journal.

In order to simplify the manufacture of the separating gap and to be able to significantly increase the elasticity of the filling piece, its width extends over the entire width of the filling piece.

A copper alloy such as brass or bronze, which has good sliding and dry running properties, is recommended as the material. Of course, another material equipped with these properties and a favorable elasticity behavior can also be used. Bi-metals or coated materials can also be used.

The constructive measure that the cavity in the sealing body extends beyond the circumference of the bearing journal facing the high-pressure region can simplify the manufacture of the separation gap in front of the cavity, for example by wire EDM. In addition, the proposed design and type of manufacture of the separation gap can save manufacturing costs.

Instead of a separating gap, given appropriate elasticity of the material used, the sealing body could have a cavity which extends over a large proportion of the filler piece and is connected, for example, to the high-pressure region via one or more bores or lateral grooves.

This cavity would be advantageous in terms of a favorable adaptability of the inner and outer legs to the outer shape of the sealing body, i.e. the walls of the cavity run approximately parallel to the outer sides of the inner and outer legs. In the case of a prefabricated casting blank, the cavity could be designed as the core of a model.

As a further alternative embodiment of the inventive concept, the filler formed from the sealing body and bearing journal could be separated into two separate parts by the separating gap, it being possible for the low-pressure and high-pressure space to be separated by a shaft arranged across the width of the separating gap.

For this purpose, the inner and outer legs are preferably provided with bearing shells. The shaft itself can be anchored or supported rotatably or rotatably in these bearing shells. The latter embodiment allows pivoting movements of the inner and outer legs in the pivot bearing formed by the shaft and bearing shells, that also separates the high pressure area from the low pressure room. The arrangement of the swivel bearing along the length of the separation gap is to be determined in coordination between the volumetric efficiency of the gear pump or motor and the wear caused by friction between the teeth and the sealing body. In comparison with the one-piece filler piece, in the embodiment according to FIG. 7, the seal between the high-pressure area and the low-pressure space takes place by means of a shaft and bearing shells on the inner 15 and outer legs 16.

Of course, as already indicated, the shaft could be offset along the length of the separating gap from the axis of the bearing journal and thus serve to seal the separating gap.

In all of the previously described embodiments, the bearing journal (s) can be arranged away from the end of the sealing body facing the low-pressure chamber.

It is expedient if the sealing body in the region of the bearing journal (s) is designed with a recessed section on at least one of the sides facing the tooth tips, so that the pivoting movements of the inner and outer legs result in favorable sealing conditions.

It is equally advantageous, if the bearing pins have a larger diameter than the height of the sealing body, that at least one outer side of the sealing body merges approximately flush with the circumference of the bearing pin.

In order to be able to keep the hydraulic forces acting on the sealing body on the filler piece balanced, it is advantageous if the bearing journal (s) are arranged on the sealing body in the line of action of the resultants resulting from the hydraulic forces acting on the sealing body; also with a shortened separation gap that ends in front of the bearing journal (s).

The shape at the end of the sealing body facing the low-pressure space is advantageously adapted to the peripheral shape of the bearing journal.

An improvement in the efficiency of the filler piece can be achieved if at least one of the inner and outer legs is designed to bear against the toothing of the ring gear and / or pinion.

Within the housing of the gear machine, the filler can be fixed rigidly or movably for its effectiveness.

Fig. 1

einen Querschnitt durch eine innenzahnradmaschine senkrecht zu deren Rotationsaxe,

Fig. 2

eine Seitenansicht eines Füllstücks,

Fig. 3

eine Ansicht des Füllstücks gemäss Pfeil A in Fig. 2,

Fig. 4

eine alternative Ausführungsform eines Füllstücks,

Fig. 5

eine weitere alternative Ausführungsform eines Füllstücks,

Fig. 6

eine andere alternative Ausführungsform eines Füllstückes und

Fig. 7

ein zweiteilig ausgebildetes Füllstück.

Exemplary embodiments of the invention are explained in the subsequent description with reference to the drawing. Show it:

Fig. 1

a cross section through an internal gear machine perpendicular to its axis of rotation,

Fig. 2

a side view of a filler,

Fig. 3

2 shows a view of the filler according to arrow A in FIG. 2,

Fig. 4

an alternative embodiment of a filler piece,

Fig. 5

another alternative embodiment of a filler piece,

Fig. 6

another alternative embodiment of a filler and

Fig. 7

a two-part filler.

1 shows an internal gear pump 1 with an internally toothed ring gear 2 and a pinion 3 meshing therewith, between which a filler 8 formed from a sealing body 7 and at least one bearing pin 6 is arranged or supported in an intermediate space 4. The filler 8 and the toothings 9, 10 of the ring gear 2 and the pinion 3 delimit the low-pressure space 11 into which the pumped medium flows on the one hand, and on the other hand there is a high-pressure region 13 between these toothings 9, 10 at the end of the sealing body 7 at the rear in the flow direction .
A dash-dotted line 12 is to illustrate the possibility of arranging the bearing journal (s) 6 on the length of the sealing body 7 in the intermediate space 4. The offset bearing journal 6 can also be seen outside a possible central axis of the sealing body 7.

2 and 3 show a further alternative embodiment of the filler piece 8, which, like in FIG. 1, is formed in one piece, with the difference that in the sealing body 7, from the rear end of which is located in the high-pressure region 13, one to the Axes of the ring gear 2 and the pinion 3, the separation gap 14, which has approximately parallel separating surfaces, extends into and ends in the bearing journal 6, in the present case the bearing journal 6 being arranged on the end of the sealing body 7 facing the low-pressure chamber 11. The separation gap 14 divides the sealing body 7 into an inner leg 15 and an outer leg 16, which are firmly connected at the end facing the low-pressure chamber 11. In the end, the separating gap 14 is formed by the two aligned bearing journals 6 in an enlarging manner by means of a continuously increasing or drop-like cavity 23 which is intended to considerably reduce the notch effect. In the separating gap 14 there is a sealing device 18, each consisting of a half-shell 19 assigned to each leg 15, 16, which together hold a sealing roller 20, which seals the opening of the continuing separating gap 14 from the high-pressure chamber 13 by the pressure from the high-pressure region 13. This sealing device 18 is arranged in coordination with an expansion caused by the pressure in the separating gap 14 on the legs 15, 16 at a corresponding location in the separating gap 14, which extends approximately through the axis of the cylindrical bearing journal 6 and at least approximately in the center of the crescent-shaped shape of the sealing body 7 is distributed. The width of the sealing body 7 is matched to those widths of the ring gear 2 and pinion 3 so that the sealing body 7 remains movable. In the area of the bearing journal 6, the sealing body 7 has a recessed section 21 on the outer leg 16 or on its outer side facing the toothing 9 of the ring gear 2. The separation gap 14, as well as the cavity 23 provided at its end, are arranged approximately centrally in the circumferential direction in the sealing body 7 and extend over the entire length of the bearing journal 6.

An alternative embodiment is shown in FIG. 4, according to which the separating gap 14 is formed at the end with a cavity 23 which continues approximately in alignment and has spaced apart partitions 22. This cavity 23 improves the elasticity and adaptability of the legs 15, 16 on the tooth heads of the toothings 9, 10 of the ring gear 2 and pinion 3 and can be left out by a core when casting the filler blank. The partition walls 22, which run approximately parallel according to FIG. 4 and are connected at the end by a regular circular curvature, could also be arranged to form a different geometric shape. Since the separation gap 14 can be produced by wire EDM, but paragraphs are a hindrance to such processing, the cavity 23 expands over the journals 6 in the sealing body 7. This embodiment could also have a sealing device 18, as can be seen in FIG. 2, and the recessed section 21 could also be provided on the opposite side of the sealing body 7 or on both sides.

Instead of a separating gap 14, the filler 8 or sealing body 7 in FIG. 5 has a crescent-shaped cavity 23 which is connected to the high-pressure region 13 by a bore 24. This embodiment is particularly suitable when using an elastic material. The dividing walls 22 are preferably arranged parallel to the outer sides of the sealing body 7 or in alignment with the curvature of the separating gap 14 and connected at both ends by curvatures.

FIG. 6 shows a filling piece 8 in which the separating gap 14 ends in an expanded form, as for example in FIG. 2, but in front of the bearing journal 6 in the sealing body 7.

7 shows a two-part filling piece 8, the separating gap 14 from the high-pressure region 13 to the low-pressure chamber 11, approximately evenly distributed over the crescent-shaped cross-sectional shape, forming two separate parts made of inner leg 15 and bearing part 25 on the one hand and outer leg 16 and bearing part 26 on the other . In the center of the bearing journal 6, which is formed from two parts 25, 26, there is a shaft 29 in bearing shells 27, 28 which, when the filler piece 8 is mounted, keeps the pressurized space of the separating gap tight with respect to the low-pressure space 11. Of course, instead of the shaft 29, a sealing device 18 - as shown in FIG. 2 - could be installed in front of the axis of the bearing journal 6 in the separating gap 14 or in addition to the shaft 29, a sealing device 18 in the separating gap 14.

The design of the filler pieces 8 according to FIGS. 1 to 7 allow the special arrangement between the sealing body 7 and the journal 6, such that the line of action of the resulting hydraulic force acting on the sealing body 7 intersects the axis of the journal 6.

Claims (21)

1. Gear pump or motor comprising a filler (8) arranged in the intermediate space formed by a pinion (3) and an internal geared wheel (2) meshing therewith, bearing at least partially against the tooth tips of the pinion and/or of the internal geared wheel and consisting of an approximately sickle-shaped seal (7) having a downwardly directed bearing pin (6) on at least one side, the seal (7) and the bearing pin (6) being formed in one piece at least as a partial mechanism of the filler (8) and the filler (8) having at least one separating gap (14) extending approximately in the circumferential direction from the high-pressure area (13) and forming internal (15) and external members (16) which can each bear at least partially against the tooth tips of the tooth gearing (9, 10) of the internal geared wheel (2) and of the pinion (3), characterised in that the bearing pin/s (6) are arranged at least approximately on the end of the seal (7) directed towards the low-pressure chamber (11) and that the separating gap (14) extends at least approximately to the end of the filler (8) directed towards the low-pressure chamber (11).
2. Gear pump or motor according to claim 1, characterised in that the separating gap (14) extends at least into the region of the filler (8) in which the bearing pins (6) are arranged.
3. Gear pump or motor according to one of claims 1 or 2, characterised in that the internal (15) and external members (16) are connected together at the end of the filler (8) directed towards the low-pressure chamber (11).
4. Gear pump or motor according to one of claims 1 to 3, characterised in that the separating gap (14) preferably has a hollow space (23) at the end directed towards the low-pressure chamber (11).
5. Gear pump or motor according to claim 4, characterised in that the hollow space (23) widens approximately continuously towards the low-pressure chamber (11).
6. Gear pump or motor according to claim 4, characterised in that the hollow space (23) has dividing walls (22) extending at a uniform spacing approximately in the circumferential direction.
7. Gear pump or motor according to claim 4, characterised in that the hollow space (23) tapers towards the low-pressure chamber (11).
8. Gear pump or motor according to one of claims 1 to 7, characterised in that the separating gap (14) is arranged at least approximately centrally in the seal (7) at least in the region of the bearing pin/s (6).
9. Gear pump or motor according to one of claims 1 to 8, characterised in that the separating gap (14) extends in its width over the entire width of the filler (8).
10. Gear pump or motor according to one of claims 4 to 9, characterised in that the hollow space (23) in the filler (8) extends beyond the circumference of the bearing pin/s (6) directed towards the high-pressure area (13).
11. Gear pump or motor according to claim 1, characterised in that at least the seal (7) has a hollow space (23) to which the pressure medium can preferably be applied.
12. Gear pump or motor according to claim 11, characterised in that the walls of the hollow space (23) are arranged approximately in parallel with the outer faces of the seal (7) bearing against the tooth gearing (9, 10) of the internal geared wheel (2) and of the pinion (3).
13. Gear pump or motor according to claim 1, characterised in that the filler (8) is formed in two pieces by a separating gap (14) extending from the end of the seal (7) directed towards the high-pressure area (13) to the end of the seal (7) directed towards the low-pressure chamber (11) and that a shaft (29) traversing the separating gap (14) in parallel is arranged between the internal (15) and external members (16).
14. Gear pump or motor according to claim 13, characterised in that the shaft (29) is supported preferably in a sealed manner in bearing cups (28) of the internal (15) and external members (16).
15. Gear pump or motor according to one of claims 13 or 14, characterised in that the shaft (29) is arranged concentrically with the axis of the bearing pin/s (6).
16. Gear pump or motor according to one claims 1 to 15, characterised in that the seal (7) has a set-back portion (21) on at least one outer face in the region of the bearing pin/s (6).
17. Gear pump or motor according to one of claims 1 to 16, characterised in that at least one of the outer faces of the seal (7) bearing against the tooth gearing (9, 10) of the internal geared wheel (2) and/or of the pinion (3) passes over in an approximately flush manner into the bearing pin/s (6).
18. Gear pump or motor according to one of claims 1 to 17, characterised in that the bearing pin/s (6) are arranged on the seal (7) along the line of application of the resultant of the hydraulic forces acting on the seal (7).
19. Gear pump or motor according to one of claims 1 to 18, characterised in that the end of the seal (7) directed towards the low-pressure chamber (11) has at least approximately the shape of the bearing pin/s (6).
20. Gear pump or motor according to one of claims 1 to 19, characterised in that at least one of the internal (15) and external members (16) bears in a preloaded manner against the tooth gearing (9, 10) of the internal geared wheel (2) and of the pinion (3).
21. Gear pump or motor according to one of claims 1 to 20, characterised in that the filler (8) is fixedly or movably secured in the housing of the gear pump or motor.

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