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

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.