Geared fluid machine with circumferential seal having first and second spaced apart seal limbs

Abstract

A geared fluid machine has a machine housing and first and second intermeshing gearwheels that are rotatably mounted in the machine housing with respect to an axis of rotation and are arranged at least partially contacting by their end faces. At least one axial washer is arranged in the machine housing with axial play and has on a distal side a pressure field surrounded by a circumferential seal. The seal contacts and seals against a first bearing surface of the axial washer, and also contacts and seals against a second bearing surface of the machine housing. The seal is at least partially U-shaped in section and has a first seal limb contacting the first bearing surface, a second seal limb contacting the second bearing surface, and a connecting limb connecting the first and second seal limbs.

Claims

1. A geared fluid machine comprising: a machine housing; and a first gearwheel and a second gearwheel meshing with the first gearwheel, the first gearwheel and the second gearwheel each rotatably mounted in the machine housing with respect to a respective axis of rotation; at least one axial washer arranged in the machine housing with axial play, the at least one axial washer having a first washer side facing away from the first and second gearwheels; and a circumferential seal surrounding a pressure field and contacting and sealing against a first bearing surface of the at least one axial washer on a first seal side of the circumferential seal, the circumferential seal including a second seal side contacting and sealing against a second bearing surface of the machine housing, the circumferential seal being at least partially U-shaped in section, and having first and second spaced apart seal limbs, the first seal limb lying against the first bearing surface, the second seal limb lying against the second bearing surface, the circumferential seal further including a connecting limb connecting the first seal limb and the second seal limb, wherein the circumferential seal, in section, is symmetric with respect to a symmetry plane extending through the connecting limb at a distance from the first and second seal limbs, and wherein each of the first and second seal limbs, in section, is delimited on an inner surface facing the other of the first and second seal limbs by a first imaginary line, and on an outer surface facing away from the other of the first and second seal limbs by a second imaginary line, wherein the first imaginary line and the second imaginary line are angled toward each other when the seal is in a relaxed state.

2. The geared fluid machine according to claim 1, wherein the circumferential seal is made of a uniform, elastic material, and/or is designed with no support ring.

3. The geared fluid machine according to claim 2, wherein the circumferential seal is made of polyurethane.

4. The geared fluid machine according to claim 1, wherein the first and second seal limbs, in section and when the circumferential seal is in the relaxed state, have free ends sharply inclined away from each other in a direction facing away from the connecting limb.

5. The geared fluid machine according to claim 1, wherein the connecting limb, in section, has at least on a side remote from the first and second seal limbs an extension in an axial direction with respect to one of the axes of rotation which is less than a distance between the first bearing surface and the second bearing surface when the axial washer is lying against the machine housing.

6. The geared fluid machine according to claim 1, wherein free ends of the second sides of the first and second seal limbs have a greater spacing from one another than a distance between the first bearing surface and the second bearing surface when the circumferential seal is in the relaxed state.

7. The geared fluid machine according to claim 1, wherein the connecting limb, in section, is rectangular and has at least one chamfer or one round edge on its side remote from the first and second seal limbs.

8. The geared fluid machine according to claim 1, wherein the connecting limb has a radial extension in a radial direction, in section, which is greater than an axial extension of either the first seal limb or the second seal limb in an axial direction.

9. The geared fluid machine according to claim 1, wherein free ends of the first and second seal limbs, in section, have at least one rounding which is between the first imaginary line and the second imaginary line, the at least one rounding extending from the first imaginary line to the second imaginary line.

10. The geared fluid machine according to claim 1, wherein the circumferential seal has at least a first seal region and at least a second seal region, wherein the first seal region and the second seal region have different seal cross-sections.

11. The geared fluid machine according to claim 10, wherein a distance between free ends of the second sides of the first and second seal limbs, when the circumferential seal is in a relaxed state, is of a first value in the first seal region and a second value in the second seal region which is different from the first value.

12. The geared fluid machine according to claim 10, wherein a height of the connecting limb has a first value in the first seal region and has a second value in the second seal region which is different from the first value.

13. The geared fluid machine according to claim 10, wherein the first seal region and second seal region transition into each other via a transition region.

14. The geared fluid machine according to claim 10, wherein the first seal region and the second seal region are connected to each other via a bend, wherein the bend has a greater curvature than the first seal region and the second seal region.

15. The geared fluid machine according to claim 1, wherein the circumferential seal is designed without a support ring.

16. The geared fluid machine according to claim 1, wherein each of the first and second seal limbs has a maximum thickness perpendicular to a height of the connecting limb, the height being greater than the maximum thickness.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic longitudinal sectional view through a portion of a geared fluid machine;

(2) FIG. 2 shows an enlarged detail of the longitudinal section view;

(3) FIG. 3 shows a sectional view of a seal in a first embodiment;

(4) FIG. 4 shows a sectional view of a second embodiment of the seal;

(5) FIG. 5 shows a schematic view of the seal in plan view;

(6) FIG. 6 shows a sectional view of the seal in a first seal region of the seal;

(7) FIG. 7 shows a sectional view of the seal in a second seal region of the seal; and

(8) FIG. 8 shows a sectional view of the seal in an alternative embodiment of the first seal region.

DETAILED DESCRIPTION

(9) FIG. 1 shows a schematic longitudinal sectional view of a geared fluid machine 1 which is configured as an internal geared fluid pump, by way of example. The geared fluid machine 1 has a first gearwheel 2 designed as a pinion, a second gearwheel 3 designed as a ring gear, and a machine housing 4. The first gearwheel 2 has an external toothing, which is not illustrated in greater detail, which partially meshes with an internal toothing, which is not illustrated in greater detail, of the second gearwheel 3. The first gearwheel 2 is rotatably mounted with respect to an axis of rotation 5, and the second gearwheel 3 is rotatably mounted about a further axis of rotation which is not illustrated, which is arranged parallel to and at a distance from the axis of rotation 5. The gearwheels 2 and 3 are thus mounted eccentrically to each other. the outer toothing of the first gearwheel 2 is at least partially spaced apart from the internal toothing of the second gearwheel 3. A filling piece 6 which is preferably crescent shaped can be arranged in this region. The filling piece 6 can be designed as a single piece or as multiple pieces.

(10) The axial washer 7 has, on a first washer side facing the machine housing 4, and therefore the gearwheels 2 and 3, a pressure field 9 which is formed by way of example in the form of a depression in the axial washer 7. The pressure field 9 can be subjected via a fluid channel 10 which is formed in the machine housing 4 to a pressurized fluid. By way of example, the pressure field 9 is connected via the fluid channel 10 to the flow of a pressure side, not illustrated here in greater detail, of the geared fluid machine 1. During operation of the geared fluid machine 1, the pressure field 9 is therefore pressurized via the fluid channel 10 and accordingly pressed axially in the direction of the gearwheels 2 and 3.

(11) In order to ensure reliable pressure buildup in the pressure field 9, a seal 11 is functionally assigned to the pressure field. The seal 11 preferably completely surrounds the pressure field 9 and in this respect is annular, if not necessarily circular. Rather, the seal 11 can be out of roundthat is, can deviate from a circular shape. by way of example, the pressure field 9 and/or the corresponding depression has an approximately kidney-shaped design, such that the seal 11 is arranged in the shape of a kidney. The seal 11 lies on one side thereof against a first bearing surface 12 of the axial washer 7, sealing the same, and on the other side thereof against a second bearing surface 13 of the machine housing 4, sealing the same. The seal 11 is made of an elastic material, such that after assembly of the geared fluid machine 11, a prestress can be applied to the axial washer 7 with the aid of the seal 11, which in turn produces a certain pressing force of the axial washer 7 on the gearwheels 2 and 3 in the axial direction.

(12) FIG. 2 shows a detail view of the longitudinal sectional view of the geared fluid machine 1 noted above. In particular, the machine housing 4 and the axial washer 7 can be seen partially, and the seal 11 can be seen in its entirety. It can be seen that the seal 11 is arranged in a recess 14 of the machine housing 4. The seal 11 is positioned with a first seal side or a first sealing surface 15 lying against and sealing the first bearing surface 12, and with a second seal side or a second sealing surface 16 lying against and sealing the second bearing surface 13. The first sealing surface 15 is present at a first seal limb 17, while the second sealing surface 16 is formed on a second seal limb 18. The two seal limbs 17 and 18 are arranged spaced apart from each other in the axial direction with respect to the axis of rotation 5, and connected via a connecting limb 19 together, such that the seal 11 is u-shaped overall in cross-section.

(13) The seal 11 isas indicated by the hatchingconstructed in one piece and of a uniform sealing material. Polyurethane can be used as a sealing material, by way of example. In particular, the seal 11 is designed with no support ringthat is, it does not have a metal supporting ring, for example. In this regard, the seal 11 consists solely of the sealing material. Alternatively, of course, a support ring as such can be included. The connecting limb 19 is substantially rectangular as seen in section, and has rounded edges 20 on its sides which face away from the seal the limbs 17 and 18. One of the round edges 20 abuts a corresponding round edge 21 of the recess 14.

(14) It will be appreciated that the recess 14 has greater dimensions than the seal 11 in the radial direction with respect to the axis of rotation 5. Due to the design of the seal 11 as a circumferential seal, the latter has an inherent spring force, which is directed to an enlargement in the radial direction, such that the seal 11 and/or its connecting limb 19 is always pressed against a step 22 which delimits the outward radial extent of the recess 14. On the side opposite the step 22 in the radial direction, the recess 14 is limited by a web 23 which separates the recess 14 from the fluid channel 10. However, the web 23 is optional and may be omitted accordingly.

(15) It can be clearly seen that the seal 11, as seen in section, is constructed symmetrically with respect to a plane of symmetry 24, wherein the plane of symmetry 24 is preferably perpendicular to the axis of rotation 5 and is arranged centrally between the seal limbs 17 and 18. In other words, the plane of symmetry 24 is perpendicular to a longitudinal central axis 25 of the connecting limb 19.

(16) FIG. 3 shows a section of the seal 11 in a first embodiment, wherein the seal 11 is in the unassembled statethat is, in particular in a pre-assembly state. Accordingly, the seal 11 is relaxed, such that the seal limbs 17 and 18, due to their spring action, continue away from each other in the axial direction on their side which face away from the connecting limb 19, such that their distance in this direction increases with increasing distance from the connecting limb 19. The plane of symmetry 24 and the longitudinal central axis 25 are also indicated. Likewise, central longitudinal axes 26 and/or 27 are indicated for each of the seal limbs 17 and 18, respectively. Furthermore, an imaginary logical separation is shown between the seal limbs 17 and 18 on the one hand and the connecting limb 19 on the other. It can therefore be seen that the connecting limb 19 constitutes a kind of base body of the seal 11 from which proceed the seal limbs 17 and 18, the same extending inwardly in the radial direction, by way of example, as viewed in longitudinal section with respect to the axis of rotation 5.

(17) Each of the seal limbs 17 and 18 comprises a free end 28 and/or 29 on its side facing away from the connecting limb 19. The seal 11 has, when viewed in section, a maximum width B, particularly on its side facing away from the connecting limb 19. The maximum width B accordingly corresponds to the maximum spacing of the seal limbs 17 and 18 and/or the maximum spacing of the sealing surfaces 15 and 16. The connecting limb 19, however, has a width b, which may be defined, for example, as the average width, or the width in the region of its longitudinal central axis 25. The width b is smaller than the width B. Furthermore, the width b of the connecting limb 19 is preferably less than or equal to a width of the recess 14 in which the seal 11 is arranged. The opposite configuration from that described above is of course feasible as well. In this case, the width b is greater than the width of the recess 14 and/or is greater than its extension in the axial direction relative to the axis of rotation 5.

(18) On its side facing away from the connecting limb 19, the seal limbs 17 and 18 are each delimited by a flat surface defined by a line 30 and/or 31. When seen in section, the line 30 is bound on one side via a rounding 32 to the first sealing surface 15 and/or to a line which defines the same, while on the other side it is bound via a rounding 33 to an inner surface 34 of the first seal limb 17 and/or to a line which defines the same. This applies analogously to the second seal limb 18; roundings 35 and 36 and an interior surface 37 are present. Each of the seal limbs when viewed in section is delimited on its side facing the other of the seal limbs 18 and/or 17 by the respective inner surface 34 and/or 37, and on its side which faces away from the other seal limb 18 and/or 17, respectively, by the respective sealing surface 15 and/or 16.

(19) For the second seal limb 18, an indication is included that the inner surface 37 is defined by a first line 38, and the sealing surface 16 is defined by a second line 39. The two lines 38 and 39, and thus extensions of the sealing surface 16 and the inner surface 37 are angled toward each other, and thus intersect each other at an angle . The angle can in principle be selected as desired. For example, it is at least 2.5, at least 5, at least 7.5 or at least 10. The seal 11 is preferably designed in such a manner that the two lines 38 and 39 and/or the sealing surface 16 and the inner surface 37 are angled toward each other when the seal 11 is in the relaxed state, but together form a smaller angle, or are arranged in parallel, after the installation of the seal in the geared fluid machine 1.

(20) In the direction of the plane of symmetry 24 and/or in a direction perpendicular to the longitudinal central axis 25, the seal 11 has a height H. This is composed of a height h.sub.1 of the connecting limb 19 and a height h2 of the seal limbs 17 and 18. The height h.sub.1 corresponds at the same time to a material thickness s1 of the connecting limb 19that is, in particular, its extension in the plane of symmetry 24 in cross-section. It can be clearly seen that the height h2 is greater than the height h.sub.1, wherein, for example, the height h2 is greater by at least 25%, at least 50%, at least 75% or at least 100% than the height h.sub.1. Additionally or alternatively, the material thickness s1 of the connecting limb 19 is greater than a material thickness s2 of the seal limbs 17 and 18. In other words, the extension of the connecting limb 19 in the radial direction with respect to the axis of rotation 5 is greater than the extension of the seal limbs 17 and 18 in the axial direction. By way of example, the material thickness s1 is at least 5%, at least 10%, at least 15%, at least 20% or at least 25% greater than the material thickness s2. Preferably, the ratio between the height H and the width b and/or the width B is chosen such that a removal from the mold of the seal 11 is possible without moving mold elements.

(21) FIG. 4 shows a sectional view of a second embodiment of the seal 11. Reference is hereby made to the foregoing details concerning the first embodiment in their entirety; only the differences are addressed in the following. These difference are that the free ends 28 and 29 of the seal limbs 17 and 18 are not delimited by lines 30 and 31; rather, the free ends 28 and 29 have continuous curves 40 and 41. Each of the curves 40 and 41 proceeds from the respective sealing surface 15 and/or 16 and extends up to the respective inner surface 34 and/or 37. The curves 40 and 41 are designed, by way of example, as segments of a circle, and are of such a size that they merge tangentially on one side into the sealing surface 15 and/or 16, and on the other side into the inner surface 34 and/or 37.

(22) FIG. 5 shows a schematic illustration of the seal 11, wherein it can be seen that it has at least one first seal region 42 and one second seal region 43in the embodiment illustrated here, two first seal regions 42 and two second seal regions 43. The seal regions 42 and 43 differ in particular with respect to their curvature. Preferably, the first seal region 42 is less curved than the second seal region 43. In instances where this description only discusses one of the first seal regions 42 and/or one of the second seal regions 43, the remarks preferably always apply analogously to each of the first seal regions 42 and/or each of the second seal regions 43.

(23) The first seal region 42 transitions into the second seal region 43 via a transition region 44. In particular, such a transition region 44 is included between each of the first seal regions 42 and each of the second seal regions 43 adjacent to the same. In the transition region 44 and/or in each of the transition regions 44, the seal has a bend 45. The bend 45 realizes, in comparison with the first seal region 42 and the second seal region 43, a greater curvature. Preferably, the curvature of the seal 11 in the bend 45 is stronger than over the entire first seal region 42 and/or the entire second seal region 43. Furthermore, the curvature of the second seal region 43 is preferably continuous throughout, and greater than in the first seal region 42. Preferably, the first seal region 42 has a straight profile, at least partially or even continuously.

(24) The first seal region 42 differs from the second seal region 43 particularly with respect to the seal cross-section. The transition region 44 can therefore be designed in such a manner that a smooth transition of the two seal regions 42 and 43 into each other is achieved, so that there is no abrupt change in the seal cross-section.

(25) FIG. 6 shows a sectional view of the seal 11 in the first seal region 42, indicated in FIG. 5 by the cut mark A. The height h.sub.1 of the connecting limb 19, which corresponds to its material thickness s1, is included in the drawing. The distance B of the sides of the seal limbs 17 and 18 facing away from each other is also indicated. The seal 11 is shown in its relaxed state.

(26) FIG. 7 shows a sectional view of the seal 11 in the second seal region 43, wherein the corresponding point in FIG. 5 is indicated by the cut mark B. The height h.sub.1 of the connecting limb 19 and the width B are again included in the drawing. It can be seen that the seal 11 preferably has a greater width B in the second seal region 43 than in the first seal region 42. However, in contrast, the height h.sub.1 for the second seal region 43 is less than for the first seal region 42.

(27) In other words, the height h.sub.1 has a first value in the first seal region 42 and a second value in the second seal region 43, wherein the second value is less than the first value. Additionally or alternatively, the width of the seal 11 in the first seal region 42 has a first value and has a second value in the second seal region 43, wherein the second value is greater than the first value.

(28) By way of example, the height h.sub.1 in the first seal region 42 relative to the height h.sub.1 in the second seal region 43 is at least 101%, at least 102%, at least 103%, at least 104% or at least 105%. However, this ratio may also be greaterat least 110%, at least 120%, at least 130%, at least 140% or at least 150%. Additionally or alternatively, the width B in the first seal region 42 with respect to the width B in the second seal region 43 is preferably at most 90%, at most 80%, at most 75%, at most 70%, at most 60% or at most 60% or at most 50%.

(29) In particular, the values for the distance B and the height h.sub.1 are selected in such a manner that for the seal regions 42 and 43 the spring action of the seal 11 in the direction of its width Bthat is, when the seal 11 is mounted between the machine housing 4 and the axial washer 7 and/or 8is the same.

(30) FIG. 8 shows a schematic sectional view of an alternative embodiment of the first seal region 42. It can be seen that the connecting limb 19 exists at the most in imaginary form, and the two seal limbs 17 and 18 are connected to each other over the entire height H of the seal 11, such that they do not have any unconnected free ends. In this case, the height h2 of the seal limb 17 and 18 is preferably the entire height H. The described configuration can alternatively also be included in the second seal region 43. Of importance, however, is that the shape of the seal 11 described initially is present in at least one of the seal regions 42 and 43, particularly with seal limbs 17 and 18 which are connected to each other by the connecting limb 19 and which each have a free end on their side facing away from the connecting limb 19.