Packing Ring, Sealing Device, Compressor, Rotational System and Method for Detecting the Condition of Wear

Abstract

A packing ring for a sealing device, having at least two segments that are arranged around a common main axis (X). In order to be able to detect the current condition of wear, the packing ring has at least one indicator means that indicates a position of at least one of the segments in a radial direction (R) perpendicular to the main axis (X) of the packing ring.

Claims

1. A sealing device, comprising: a housing and at least one packing ring, wherein the packing ring comprises at least two segments that are arranged around a common main axis (X) and spaced apart from each other in a circumferential direction, wherein the sealing device comprises a sensor device which detects a position of at least one of the segments in a radial direction (R) perpendicular to the main axis (X) of the packing ring.

2. The sealing device according to claim 1, wherein the packing ring has at least one indicator means that indicates a position of at least one of the segments in the radial direction R perpendicular to the main axis X of the packing ring.

3. The sealing device according to claim 2, wherein the sensor device interacts with the indicator means and/or the packing ring.

4. The sealing device according to claim 1, wherein the sensor device comprises at least one sensor element.

5. The sealing device according to claim 4, wherein the at least one sensor element is arranged at an angle (ß) to the radial direction (R), where 0°<ß<90°.

6. The sealing device according to claim 4, wherein the at least one sensor element is a distance-measuring sensor element.

7. The sealing device according to claim 4, wherein the at least one sensor element is an eddy current sensor.

8. The sealing device according to claim 4, wherein the at least one sensor element is an optical sensor element.

9. The sealing device according to claim 8, wherein the optical sensor element is a confocal sensor.

10. The sealing device according to claim 1, wherein the housing comprises at least two chamber disks, wherein at least one packing ring is situated between two adjacent chamber disks.

11. The sealing device according to claim 10, wherein at least one of the at least two chamber disks comprises a slot for an indicator pin of a packing ring.

12. The sealing device according to claim 11, wherein the indicator pin is led in the slot.

13. The sealing device according to claim 12, wherein the slot is situated with a radial spacing from the packing ring.

14. The sealing device according to claim 12, wherein the at least one chamber disk comprises a bore for the slot of a sensor element and/or a sensor line.

15. The sealing device according to claim 14, wherein at least one sealing element is situated between the at least two chamber disks in the area of the bore.

16. The sealing device according to claim 10, wherein the at least one chamber disk comprises a viewing element.

17. The sealing device according to claim 16, wherein the viewing element consists of quartz glass.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The invention shall be explained and represented as an example below, with the aid of the drawings. There are shown:

[0054] FIG. 1, a first embodiment of a packing ring according to the invention in a perspective view;

[0055] FIG. 2, a second embodiment of a packing ring according to the invention in a perspective view;

[0056] FIG. 3, a side view of the packing ring of FIG. 2 with a sensor element;

[0057] FIG. 4, an embodiment of a packing ring with a sensor element in a schematic view;

[0058] FIG. 5, a further embodiment of a packing ring according to the invention with a sensor device in a schematic view;

[0059] FIG. 6, a first embodiment of a sealing device according to the invention in a schematic view;

[0060] FIG. 7, a second embodiment of a sealing device according to the invention in a schematic view;

[0061] FIG. 8, a compressor according to the invention;

[0062] FIG. 9, a rotational system according to the invention;

[0063] FIG. 10, a diagram of a wear measurement.

DETAILED DESCRIPTION OF THE INVENTION

[0064] FIG. 1 shows a packing ring 10 with three segments 20. The three segments 20 have a common inner circumferential surface 24. When used as intended, the segments 20 lie by the inner circumferential surface 24 for example against a piston rod (not shown here) and seal it off there. The segments 20 are arranged about a common main axis X.

[0065] Between every two adjacent segments 20 there is provided a gap 15 in the circumferential direction. When used as intended, the segments 20 wear down in the area of the inner circumferential surface 24. As a result, the segments 20 gradually move toward the main axis X. Thanks to this movement, the gaps 15 gradually become smaller, until the segments 20 lie directly against each other. The segments 20 then cannot move further in the direction of the main axis X, so that upon further wear at the inner circumferential surface 24 the packing ring 10 becomes leaky there.

[0066] In order to enable complete tightness, two packing rings 10 can be arranged in succession in the direction of the main axis X. The packing rings 10 will be twisted relative to each other in the circumferential direction so that each gap 15 of a packing ring 10 is covered over by the segment 20 of the other respective packing ring 10.

[0067] The packing ring 10 has three support elements 16. The support elements 16 and the segments 20 are arranged alternating in the circumferential direction of the packing ring 10. The support elements 16 have a common outer circumferential surface 22 with the segments 20. The outer circumferential surface 22 has the form of an envelope surface of a cylinder.

[0068] In the area of the outer circumferential surface 22 there is provided a groove 14. The groove 14 extends in the circumferential direction over the entire outer circumferential surface 22. A tube spring 12 is arranged in the groove 14. The tube spring 12 produces a force directed at the main axis X. In this way, the segments 20 when used as intended are pressed against the piston rod (not shown). The tube spring 12 is represented schematically in all the figures.

[0069] The packing ring 10 comprises an indicator means 30 in the form of an indicator pin 32. The indicator pin 32 is arranged in the area of the outer circumferential surface 22 on a segment 20. The indicator pin 32 is of cylindrical base shape and has a slanted surface 34. The indicator pin 34 is situated such that the longitudinal axis of the cylindrical base shape extends in the radial direction R. The radial direction R forms a right angle with the main axis X.

[0070] FIGS. 2 and 3 show a packing ring 10 according to a second embodiment. Compared to the embodiment of FIG. 1, the segments 20 and the support elements 16 differ in their shape. The invention can be applied to many different known packing rings 10.

[0071] FIG. 3 shows in addition a sensor element 42 with a cylinder axis Z. The cylinder axis Z is parallel to the main axis X of the packing ring 10. The sensor element 42 is oriented to the slanted surface 34 of the indicator pin 32. The slanted surface 34 is situated at an angle α to a radial direction R. The angle α is around 7°. The cylinder axis Z is situated at an angle ß to the radial direction R. The angle ß amounts to 90°.

[0072] The sensor element 42 determines its distance from the slanted surface 34 of the indicator pin 32. With increasing wear, the segments 20 move toward the main axis X. The indicator pin 32 is connected to a segment 20. Therefore, the indicator pin 32 also moves due to wear toward the main axis X. In this way, the distance between sensor element 42 and slanted surface 34 gradually increases, while in particular the distance along the cylinder axis Z is measured. The continuous increasing of the distance is detected by the sensor element 42 and can be indicated and/or processed on an evaluation device (not shown here). The sensor element is connected by means of a sensor line 44 to the evaluation device.

[0073] FIG. 4 shows schematically a packing ring 10 with two segments 20. The segments 20 are designed as half-shells and are situated about a common main axis X. A sensor element 42 with a cylinder axis Z is oriented toward one of the segments 20. The sensor element 42 is a cylindrical body. The packing ring 10 represented in FIG. 4 with the sensor element 42 is part of a sealing device according to the invention, not fully represented in FIG. 4.

[0074] The cylinder axis Z corresponds to the radial axis R. The angle ß between the cylinder axis Z and the radial direction R in this arrangement amounts to 0°.

[0075] At the sensor element 42 there is arranged a sensor line 44. The sensor line 44 leads to an evaluation device (not shown here). The sensor element 42 in the embodiment shown is an eddy current sensor, i.e., a distance-measuring sensor element 42. When used as intended, the sensor element 42 continuously detects the distance between sensor element 42 and segment 20. Owing to wear, the segments 20 move in the direction of the main axis X, so that the distance between sensor element 42 and segment 20 increases. The wear can be determined from the distance.

[0076] FIG. 5 shows a further embodiment of a packing ring 10. The packing ring 10 has four segments 20, which are arranged about a common main axis X. On each of two opposite segments 20 is arranged an indicator pin 32. The indicator pins 32 extend in a common radial direction R. Each indicator pin 32 is fastened by a respective bolt 36 in form fitting manner to a segment 20.

[0077] The indicator pins 32 each have a slanted surface 34. The slanted surfaces 34 are respectively situated at an angle α to the radial direction R. In the embodiment shown, α˜7°.

[0078] A sensor device 40 comprises two sensor elements 42. One sensor element 42 is associated respectively with an indicator pin 32. The sensor elements 42 each have a cylindrical shape with a cylinder axis Z. The cylinder axes Z are each situated at an angle ß to the radial direction R. In the embodiment shown, ß=90°.

[0079] The sensor elements 42 are respectively attached across a sensor line 44 to an evaluation device 46. The evaluation device 46 receives the signals of the sensor elements 42 and displays them to a user. In addition, an end value for the position of the indicator pins 32 is set in memory in the evaluation device 46. If this end value is surpassed for one of the two indicator pins 32, a warning is given through the evaluation device 46.

[0080] FIG. 6 shows a sealing device 1 with a housing 50 and a packing ring 10 according to the invention arranged in the housing 50. The sealing device 1 is a piston rod packing for the sealing of a piston rod 110. In the housing 50, furthermore, three additional packing rings 60 are arranged. The packing ring 10 has a plurality of segments 20, which are arranged around a common main axis X.

[0081] The housing 50 comprises five chamber disks 52. All the packing rings 10, 60 are arranged respectively between a cover ring 11 and a support ring 13. Each chamber disk 52 comprises an inner space in which either a packing ring 10, 60 with the corresponding cover ring 11 and support ring 13 or a throttle ring 4 is arranged. A chamber disk 52 is arranged on a first side of a flange 51. On a second side of the flange 51 opposite the first side is arranged a top piece 55, in which a leakage gas seal 5 is arranged.

[0082] The packing rings 10, 60, the throttle ring 4, the cover rings 11 and individual rings of the leakage gas seal 5 are each subjected to force by a tube spring 12 directed at the main axis X. In this way, these rings thrust against the piston rod 110.

[0083] The packing ring 10 comprises an indicator pin 32. The chamber disk 52 of the packing ring 10 comprises a slot 54 for the indicator pin 32. The indicator pin 32 has a slanted surface 34. Due to the wear of the segments 20 of the packing ring 10, the indicator pin 32 moves in the slot 54 toward the main axis X. A sensor element 42 is directed at the slanted surface 34 of the indicator pin 32. The sensor element 42 continuously ascertains the distance from the slanted surface 34. The sensor element 42 is screwed into a chamber disk 52. The sensor element 42 is an eddy current sensor. The sensor element 42 is connected by means of the sensor line 44 to an evaluation device (not shown here).

[0084] Four chamber disks 52 and the flange 51 have a common bore 53 for the sensor element 42 and a sensor line 44. In the area of the bore 53, a sealing element 56 is arranged between every two chamber disks 52 or a chamber disk 52 and the flange 51. The sealing elements 56 prevent leakiness from being caused by the bore 53.

[0085] FIG. 7 shows a further embodiment of a sealing device 1 according to the invention. The sealing device 1 comprises a housing 50 with five chamber disks 52, a flange 51 and a top piece 55, through which a piston rod 110 extends.

[0086] The chamber disks 52 respectively have an inner space, in which either a packing ring 10, 60 together with a support ring 13 or a throttle ring 4 is located. The packing rings 10, 60 are of traditional design. In the interior of the top piece 55 there is arranged a leakage gas seal 5.

[0087] The sealing device 1 comprises an optical sensor element 42 in the form of a confocal sensor. The chamber disk 52 of the packing ring 10 comprises a viewing element 58 radially outside the packing ring 10. The viewing element 58 in the embodiment shown is a disk of quartz glass. The sensor element 42 is arranged radially outside the viewing element 58. The viewing element 58 is located between the packing ring 10 and the sensor element 42.

[0088] The packing ring 10 comprises a plurality of segments 20 which are arranged about a common main axis X. The confocal sensor has a cylindrical base shape. It is built in a 90° design. In this design, the measuring direction is perpendicular to a cylinder axis Z of the cylindrical base shape. The cylinder axis Z is arranged parallel to the main axis X. The measuring direction of the sensor element 42 is thus parallel to a radial direction R of the packing ring 10.

[0089] The sensor element 42 generates a beam path by means of which the distance between the sensor element 42 and a segment 20 of the packing ring 10 is determined. If the segment 20 moves on account of wear toward the main axis X, the distance will become greater. In this way, the wear on the segment 20 can be determined.

[0090] The sensor element 42 is attached by means of the sensor line 44 to an evaluation device (not shown here).

[0091] FIG. 8 shows a compressor 100 according to the invention with a sealing device 1. The compressor 100 comprises a compressor housing 101, in which a piston rod 110 is arranged. The piston rod 110 when used as intended executes an oscillating movement and is driven by a crank (not shown).

[0092] The compressor 100 comprises a compression chamber 102, in which process gas can be compressed. In the compression chamber 102 there is arranged a piston 112. The piston 112 is connected to the piston rod 110. Starting from the compression chamber 102, the compressor 100 comprises along the main axis X a first intermediate piece 104, a second intermediate piece 106 and a crankcase 108. The piston rod 110 extends from the compression chamber 102 as far as the crankcase 108.

[0093] The piston rod 110 and piston 112 are represented in two states. In a first state, the piston 112 is situated at a first turning point. At a turning point the velocity of the piston is equal to zero. In the first state, the process gas occupies the greatest possible volume in the compression chamber 102. In a second state, the piston 112 is situated at a second turning point. In the second state, the process gas has been compressed and occupies a lesser volume. Not shown in FIG. 8 are an inlet and an outlet for the process gas.

[0094] Between the compression chamber 102 and the first intermediate piece 104 is situated the sealing device 1. The sealing device 1 is designed as a piston rod packing. The sealing device 1 comprises a housing 50, in which a packing ring 10 is arranged. The packing ring 10 comprises an indicator pin 32, which extends radially outward from the packing ring 10. The packing ring 10 is arranged together with a support ring 13 between two chamber disks 52 of the housing 50.

[0095] The compressor 100 comprises a sensor device 40. The sensor device has a sensor element 42, a sensor line 44 and an evaluation device 46. The sensor element 42 is arranged in the housing 50. The sensor line 44 connects the sensor element 42 to the evaluation device 46. The sensor element 42 in the embodiment shown is an eddy current sensor. The housing 50 comprises a bore 53 for the sensor element 42 and a portion of the sensor line 44.

[0096] Between the first intermediate piece 104 and the second intermediate piece 106 there is arranged an intermediate seal 105. The intermediate seal 105 is an additional safeguard and prevents the process gas which has gotten into the first intermediate piece 104 despite the sealing device 1 from getting into the second intermediate piece 106. Between the second intermediate piece 106 and the crankcase 108 is arranged an oil wiper seal 107. The oil wiper seal 107 makes sure that the least possible lubricant, especially oil, gets from the crankcase 108 into the second intermediate piece 106.

[0097] FIG. 9 shows a rotational system 70 according to the invention. The rotational system 70 comprises a shaft 72 with a shaft axis W. The shaft 72 is rotatably mounted about the shaft axis W. On the shaft 72 is arranged a packing ring 10.

[0098] The packing ring 10 comprises three segments 20. The segments 20 are arranged about a common main axis X, which in the embodiment shown corresponds to the shaft axis W. On one segment 20 there is mounted an indicator pin 32. The indicator pin 32 extends in the radial direction R away from the segment 20. A sensor element 42 with a cylinder axis Z is directed at the indicator pin 32.

[0099] Optional components of the rotational system 70, not shown, include a housing, a bearing for the shaft, and a drive mechanism.

[0100] FIG. 10 shows a diagram of a wear measurement. On the ordinate axis is plotted the time of the measurement, in hours. On the abscissa axis is plotted the signal strength of the sensor element in Volts.

[0101] One can see the signal of an eddy current sensor, which is directed at the slanted surface of the indicator pin, mounted on a segment. The segment is part of a packing ring in a piston rod seal of a piston compressor. The material used for the segments was a quick-wearing PTFE in order to minimize as much as possible the time of the experiment until total wear of the sealing ring. The packing ring seals off a dynamic pressure of 30 bar to 80 bar. The medium being sealed off was nitrogen.

[0102] One notices that at the start of the experiment the system is running in for the first 36 h and an initial value of 5 V is maintained. During this time, pressure and temperature are adjusted to the final steady state.

[0103] After this run-in phase there is found a continuous rise in the signal. This rise reflects the continuous wearing of the segment with which the sensor element is associated. Transient fluctuations (“trembling”) are attributed to pressure fluctuations and the movement of the piston rod. At around 95 h, the value of almost 10 V is reached, which corresponds to a wear of 100%. At the time, the segments of the packing ring are lying against each other, so that the lifetime was used up.

[0104] Thus, for comparable packing rings, an end value of 9 V could be indicated. At this end value, an evaluation device could put out a warning signal.

LIST OF REFERENCE NUMBERS

[0105] 1 Sealing device [0106] 4 Throttle ring [0107] 5 Leakage gas seal [0108] 10 Packing ring [0109] 11 Cover ring [0110] 12 Tube spring [0111] 13 Support ring [0112] 14 Groove [0113] 15 Gap [0114] 16 Support element [0115] 20 Segment [0116] 22 Outer circumferential surface [0117] 24 Inner circumferential surface [0118] 30 Indicator means [0119] 32 Indicator pin [0120] 34 Slanted surface [0121] 36 Bolt [0122] 40 Sensor device [0123] 42 Sensor element [0124] 44 Sensor line [0125] 46 Evaluation device [0126] 50 Housing [0127] 51 Flange [0128] 52 Chamber disk [0129] 53 Bore [0130] 54 Slot [0131] 55 Top piece [0132] 56 Sealing element [0133] 58 Viewing element [0134] 60 Additional packing ring [0135] 70 Rotational system [0136] 72 Shaft [0137] 100 Compressor [0138] 101 Compressor housing [0139] 102 Compression chamber [0140] 104 First intermediate piece [0141] 105 Intermediate seal [0142] 106 Second Intermediate piece [0143] 107 Oil wiper seal [0144] 108 Crankcase [0145] 110 Piston rod [0146] 112 Piston [0147] R Radial direction [0148] W Shaft axis [0149] X Main axis [0150] Z Cylinder axis [0151] α Angle [0152] ß Angle