Flow machine for a fluid having a radial sealing gap and a stationary wear ring

1. A flow machine for a fluid having a radial sealing gap which is formed between stator parts and a closed impeller, wherein the flow machine is designed for an operating pressure of more than 240 bar, with at least one wear ring arranged in a stationary manner being provided at the sealing gap and having an inner side facing the impeller, an outer side and two axially spaced apart side surfaces, characterized in that a concentrically extending recess is formed in the wear ring in the form of a radial gap or of a radial incision; in that the recess, starting from one of the side surfaces, extends in the axial direction over more than a fifth of the axial length of the wear ring; and in that the wear ring is produced from metal, hard metal or ceramic material, wherein the outer side of the wear ring is connected on the one side directly to the stator part and a radial gap whose axial length is larger than a fourth or larger than a third of the axial length of the wear ring is formed on the other side of the wear ring in the axial direction between it and the stator part.

2. The flow machine in accordance with claim 1 , wherein the flow machine is a pump or a centrifugal pump or a radial flow pump.

3. The flow machine in accordance with claim 1 , wherein the flow machine or pump is designed for an operating pressure of more than 360 bar.

4. The flow machine in accordance with claim 1 , wherein the wear ring is connected to the stator part on the one side by any one or more of a shrunk fit, weld connection, solder connection, and screw connection.

5. The flow machine in accordance with claim 1 , wherein the recess in the wear ring starts from that side on which the wear ring is connected at the outside to the stator part.

6. The flow machine in accordance with claim 1 , wherein the wear ring is arranged at the inlet of the impeller and surrounds it at this point.

7. A wear ring for a flow machine for a fluid, which is designed for an operating pressure of more than 240 bar, and which has a radial sealing gap which is formed between stator parts and a closed impeller, with the wear ring having an inner side facing the impeller in use, an outer side and two axially spaced apart side surfaces and being provided for stationary arrangement at the sealing gap in use, characterized in that a concentrically extending recess in the form of a radial gap or of a radial incision is provided in the wear ring; in that the recess, starting from one of the side surfaces, extends in the axial direction over more than a fifth of the axial length of the wear ring; and in that the wear ring is produced from metal, hard metal or ceramic material, wherein the outer side of the wear ring is configured to be directly connected on the one side to the stator part and further configured such that a radial gap whose axial length is larger than a fourth or larger than a third of the axial length of the wear ring is formed on the other side of the wear ring in the axial direction between it and the stator part.

8. The wear ring in accordance with claim 7 , wherein the wear ring is made from one piece.

9. The wear ring in accordance with claim 7 , wherein the wear ring is rotationally symmetrical.

10. The wear ring in accordance with claim 7 , wherein the wear ring is formed cylindrically on the inner side and/or on the outer side.

11. The wear ring in accordance with claim 7 , wherein the recess extends in the axial direction over more than a third or more than half the axial length of the wear ring.

12. The wear ring in accordance with claim 7 , wherein the wear ring has a reduced length at the outer side.

13. The wear ring in accordance with claim 7 , wherein the inner side of the wear ring has a surface structure.

14. The wear ring in accordance with claim 7 , wherein the material of the wear ring has a coefficient of thermal expansion of less than 15×10 −6 /° C.

15. The wear ring in accordance with claim 13 , wherein the surface structure is any one or more of circumferentially designed grooves, knurlings, and honeycomb structures.

16. The wear ring in accordance with claim 7 , wherein inner side of the wear ring is ground or polished.

17. A flow machine for a fluid, comprising:

at least one stator part;

a closed impeller;

a radial sealing gap between the stator part and the impeller;

a wear ring disposed in the sealing gap and having an inner side comprising an inner side surface facing the impeller, and an outer side comprising an outer side surface opposite and axially spaced apart from the inner side surface,

wherein the wear ring comprises a concentrically extending recess defining an additional radial gap, wherein the recess extends from the inner side surface or the outer side surface of the wear ring in an axial direction over more than a fifth of an axial length of the wear ring,

wherein the wear ring comprises metal, hard metal, or ceramic material,

wherein the outer side of the wear ring abuts the stator part and is fixedly attached to the stator part,

and wherein the inner side of the wear ring is spaced apart from the stator part by a radial gap, wherein the radial gap comprises an axial length which is larger than a fourth of the axial length of the wear ring.

18. The flow machine in accordance with claim 17 , wherein the outer side of the wear ring is fixedly attached to the stator part by any one or more of:

a shrunk fit directly between the stator part and the outer side of the wear ring,

a weld connection directly between the stator part and the outer side of the wear ring,

a solder connection directly between the stator part and the outer side of the wear ring, and

a screw connection directly between the stator part and the outer side of the wear ring.