DEVICE FOR TENSIONING A STUFFING BOX PACKING

Abstract

Disclosed is a device for tensioning a stuffing box packing which abuts against a superordinate assembly which is to be sealed by the stuffing box packing and which, such as the stuffing box packing, does not belong to the tensioning device. The device comprises a stuffing box gland, which is designed and intended to abut against a free side of the stuffing box packing, and a plurality of tensioning elements, which are designed and intended to press the stuffing box gland against the stuffing box packing and thus the stuffing box packing against the superordinate assembly. A separate motor drive unit is associated with each of the tensioning elements.

Claims

1. A device for tensioning a stuffing box packing which abuts against a superordinate assembly which is to be sealed by the stuffing box packing and which, like the stuffing box packing, does not belong to the tensioning device, the device comprising: a stuffing box gland, which is designed and intended to abut against a free side of the stuffing box packing; and a plurality of tensioning elements which are designed and intended to press the stuffing box gland against the stuffing box packing and thus the stuffing box packing against the superordinate assembly, wherein a separate motor drive unit is associated with each of the tensioning elements.

2. The tensioning device according to claim 1, wherein at least one of the motor drive units comprises a fluidically drivable motor drive unit.

3. The tensioning device according to claim 1, wherein at least one of the motor drive units comprises a reduction gear.

4. The tensioning device according to claim 3, wherein the reduction gear is a worm gear that is connected to the motor drive unit on an input side, where a worm of the worm gear is in reduction engagement on an output side with an axially fixed spline element of the worm gear, and where the spline element is in threaded engagement with a tensioning element of the plurality of tensioning elements that is axially displaceable but rotatably arranged.

5. The tensioning device according to claim 4, wherein the spline element is formed with a tool engagement profile at its free end, wherein the free end is an end facing away from the tensioning element.

6. The tensioning device according to claim 1, wherein the stuffing box gland or an element connected to it has at least one axial through-opening, in which an axial plain bearing is accommodated, which is designed and intended to come into sliding engagement with an associated guide pin attached to the superordinate assembly.

7. The tensioning device according to claim 1, wherein the stuffing box gland has a substantially rectangular cross-sectional area in a section taken orthogonal to its longitudinal extension.

8. The tensioning device according to claim 7, wherein a long side of the rectangular cross-sectional area is at least three times as long as a short side of the rectangular cross-sectional area.

9. The tensioning device according to claim 1, wherein the stuffing box gland is divided into a plurality of segments.

10. The tensioning device according to claim 9, wherein free ends of two mutually adjacent segments are designed to interlock in a positive-locking manner.

11. The tensioning device according to claim 10, wherein the positive locking acts in at least two of an axial direction, a radial direction and a circumferential direction.

12. The tensioning device according to claim 1, wherein free ends of at least two mutually adjacent segments are connected to one another by means of at least one radially running screw, and/or the free ends of at least two mutually adjacent segments are connected to one another by means of a coupling element abutting axially on the segments.

13. The tensioning device according to claim 1, wherein at least one distance sensor, which is designed and intended to detect a distance of the stuffing box gland from the superordinate assembly, is arranged in each case at at least three points distributed over a circumference of the stuffing box gland.

14. The tensioning device according to claim 1, wherein at least one pressure sensor is provided, which is designed and intended to detect a pressure at which drive fluid is supplied.

15. The tensioning device according to claim 1, wherein the tensioning device further comprises a valve arrangement which is designed and intended to supply drive fluid to the motor drive units or to discharge drive fluid from them again.

16. The tensioning device according to claim 15, wherein a separate valve unit is associated with each motor drive unit.

17. The tensioning device according to claim 16, wherein at least one valve unit comprises a 5/3-way valve.

18. The tensioning device according to claim 15, wherein a control unit is provided, which is designed and intended to control the valve units jointly in a first operating mode in the sense of a drive fluid supply or discharge, and in a second operating mode to control the valve units individually or in subgroups in the sense of a drive fluid supply or discharge.

19. The tensioning device according to claim 2, wherein the fluidically drivable motor drive unit is a pneumatically drivable motor drive unit.

20. The tensioning device according to claim 2, wherein the fluidically drivable motor drive unit is a pneumatically operable radial piston motor.

Description

[0030] Embodiments according to the invention are described in more detail below by way of example and with reference to the following drawings, which show:

[0031] FIG. 1 a perspective view of a rotary pressure filter equipped with an embodiment of the device according to the invention;

[0032] FIG. 2 a side cross-section of a section of the rotary pressure filter and the device according to the invention as shown in FIG. 1;

[0033] FIG. 3 a front view of a stuffing box gland according to the invention viewed in the axial direction;

[0034] FIG. 4 an enlarged view of detail IV of the stuffing box gland as shown in FIG. 3;

[0035] FIG. 5 the detail IV of the stuffing box gland as shown in FIG. 4, but seen in the radial direction;

[0036] FIG. 6 a side cross-section of a guide pin of the stuffing box gland;

[0037] FIG. 7 a frontal view of a section of a rotary pressure filter according to the invention;

[0038] FIG. 8 a side cross-section illustrating the structure and function of a distance sensor;

[0039] FIG. 9 a schematic representation of a valve arrangement according to the invention;

[0040] FIG. 10 an enlarged schematic representation of a motor drive unit according to the invention with a valve unit as shown in FIG. 9.

[0041] In FIGS. 1 and 2, a rotary pressure filter is generally designated with reference sign 10 as an example of a superordinate assembly. Along a longitudinal axis 12, which describes the axial direction, a device 14 according to the invention for tensioning a stuffing box packing 42 is installed at a front end and at a rear end of the rotary pressure filter 10. A radial direction 13 runs orthogonally to the longitudinal axis 12 (see FIG. 4). Each of the tensioning devices 14 comprises a plurality of tensioning elements 16. A separate fluidically drivable motor drive unit 18 is associated with each of the tensioning elements 16. The motor drive unit 18 can, for example, be a pneumatically operable radial piston motor.

[0042] With reference to FIG. 2, a reduction gear 20, for example a worm gear, is connected to the motor drive unit 18. A worm (not shown) is in reduction engagement with an axially fixed spline element 24 and forms the worm gear 20 with this. The spline element 24 is essentially cylindrical with the spline pointing radially outwards.

[0043] A tool engagement profile 26 is formed at a free end 24a of the spline element 24, i.e. an end located further outwards axially. This tool engagement profile 26 may be designed as a hexagonal profile, for example.

[0044] The motor drive unit 18 is supported by means of holders 28 on a cover element 30, which in turn is attached to a stationary element 32 of the rotary pressure filter 10, for example by screws, rivets, adhesives and the like. On the one hand, these holders 28 prevent the drive unit 18 from rotating about the longitudinal axis of the spline element 24 and on the other hand, also prevent the worm 22 and the spline element 24 from slipping axially. A cover opening 30a is provided in the cover element 30, through which the spline element 24 projects into the cover element.

[0045] At its axially further inward end section 24b, the spline element 24 is designed as a hollow rod and is in threaded engagement with the tensioning element 16. For this purpose, the spline element 24 has an internal thread 24c and the tensioning element 16 is provided with an external thread 16a, which is in threaded engagement with the internal thread 28c of the spline element 24. This allows the tensioning element 16 to be axially displaceable.

[0046] The spline element 24 is guided through a through-opening 34 of a stabilizing element 36 at the axially further inward end section 24b. A bearing is provided in the through-opening 34, which is designed and intended to support a rotational movement of the spline element 24. The stabilizing element 36 is connected to the stationary element 32 of the rotary pressure filter 10 in an operationally fixed manner, for example by screws, rivets, adhesives and the like.

[0047] Axial movement of the spline element 24 outwards in the axial direction may be avoided by the spline element 24 having a radial shoulder 24d at its axially further inward end, which abuts on the stabilizing element 36.

[0048] At its end which is opposite to the internal thread 16a, the tensioning element 16 abuts on the stuffing box gland 38 with a receptacle 40. The interaction of the receptacle 40 with the stuffing box gland 38 also prevents the tensioning element 16 from rotating when the spline element 24 is rotated and thus produces a positioning movement of the tensioning element 16 against the stuffing box gland 38.

[0049] The stuffing box gland 38 is arranged in such a way that it presses against a stuffing box packing 42, which in this case comprises several stuffing box packing rings 44. On its side facing away from the stuffing box gland 38, the stuffing box packing 42 abuts on a radially inward-facing shoulder 46 of the stationary element 32 of the rotary pressure filter 10. On its radially outer side, the stuffing box packing 42 abuts on the stationary element 32 of the rotary pressure filter 10. And on its radially inner side, the stuffing box packing 42 abuts on a movable element 48 of the rotary pressure filter 10.

[0050] In a section taken orthogonal to its longitudinal extension, as shown in FIG. 2, the stuffing box gland 38 has a substantially rectangular cross section. In the embodiment shown in FIG. 2, the long side of the rectangle extends in the axial direction and is approximately three times as long as the short side of the rectangle.

[0051] The procedure for tensioning the stuffing box packing 42 is as follows. The motor drive unit 18 rotates the spline element 24 by means of the worm gear 20. Due to the fact that the internal thread 24c of the spline element 24 is in engagement with the external thread 16a of the tensioning element 16 and the receptacle 40 interacts with the stuffing box gland 38, the rotational movement of the spline element 24 is transferred to the tensioning element 16 in such a way that the latter is retracted and/or extended in the axial direction. The axial movement of the tensioning element 16 causes an analogous axial movement of the stuffing box gland 38. When the stuffing box gland 38 moves axially in the direction of the stuffing box packing shoulder 46, the stuffing box packing 42 is pressed against the stuffing box packing shoulder 46 and expands in radial direction. In this way, the stuffing box packing 42 seals the stationary element 32 and the movable element 48 at its sliding surface. It goes without saying that the rotation direction of the spline element 24 only needs to be reversed in order to release the stuffing box packing 42.

[0052] With reference to FIGS. 3 to 5, the stuffing box gland 38 is substantially ring-shaped, wherein it may have a plurality of interconnected segments 38a (see FIG. 3) or 38b, 38c (see FIGS. 4 and 5). Two mutually adjacent segments are connected to each other at connecting sections 50.

[0053] The detailed view in FIG. 4 shows how a first segment 38b interlocks with a second segment 38c. For this purpose, the first segment 38b has a recessed end section 38d at a first end. Adjacent to the recessed end section 38d, the first segment 38b is provided with a recess 38e. The adjacent (second) end of the second segment 38c is designed correspondingly complementary to the first end of the first segment 38b, so that a positive-locking connection is formed at least in the radial and circumferential direction. For example, the recessed end section 38d and the recess 38e of the first segment 38b may be recessed radially outwards and the second segment 38c may be formed with a corresponding contour radially inwards.

[0054] Furthermore, a coupling element 52 is provided on the connecting section 50, which abuts axially on the adjacent segments 38b, 38c. This coupling element 52 abuts on the segments 38b, 38c and connects the first segment 38b and the second segment 38c to one another. For this purpose, the coupling element 52 is fastened, for example screwed, to the adjacent segments 38a by means of fastening elements 54.

[0055] As can be seen from FIG. 5, the two adjacent segments 38b, 38c are also connected to each other by means of radially running screws 56. The screws 56 may run through the recess 38e of one segment and the recessed end section 38d of the adjacent segment. In order to further increase stabilization, two screws 56 may run from radially outward to radially inward, and two screws 56 of the same connecting section 50 may run in the opposite direction.

[0056] According to FIG. 6, the coupling element 52 is also provided with an axial through-opening 60. An axial plain bearing 62 is accommodated in this axial through-opening 60, through which a guide pin 64 passes. The guide pin 64 is not only connected to the stuffing box gland 38 by means of the coupling element 52 but is also attached to the superordinate assembly 10 by means of the stationary element 32. For this purpose, the stationary element 32 has a threaded hole 66 into which an end section 64a of the guide pin 64 is screwed. The guide pin 64 is provided with a projection 68 at a section adjacent to the end section 64a, which abuts on the stationary element 32. The stuffing box gland 38 may be supported in the circumferential direction by means of the guide pin 64, so that such movement components cannot have any detrimental effect on the function of the tensioning device, in particular the tensioning elements 16.

[0057] Furthermore, a device 14 according to the invention may be provided with a distance sensor 70 (see FIG. 7). The distance sensor 70 can, for example, be attached to the cover element 30 in an operationally fixed manner, so that it detects a distance of the stuffing box gland 38 from the superordinate assembly 10 through the cover opening 30a. This may be, for example, a distance 72 (see FIG. 8) between the axially outer end of the stuffing box gland 38 and the axially outer surface of the movable element 48. In this way, an inclined position of the stuffing box gland 38 may be detected.

[0058] FIG. 9 shows a schematic representation of a valve arrangement 80 according to the invention, with which motor drive units 18 are controlled in order to retighten the tensioning elements 16 of the stuffing box packing 42.

[0059] The number of motor drive units 18 corresponds to the number of tensioning elements 16. In the exemplary embodiments shown in FIG. 1, a device 14 according to the invention with eight tensioning elements 16 respectively is provided at the front and rear ends of the rotary pressure filter 10 as viewed in the axial direction. However, it goes without saying that the invention is not limited to this number.

[0060] The valve arrangement 80 is designed and intended to supply a drive fluid F to the fluidically drivable drive units 18 or to discharge it again from these. A valve unit 82 is associated with each fluidically drivable drive unit 18 for this purpose. The drive fluid F is supplied to the valve units 82 by means of a line system 84 and discharged from them again.

[0061] The pressure with which the drive fluid F is supplied to the valve units 82 may be detected by means of a pressure sensor 86. Furthermore, an electrically controlled pressure reducer 88 may be provided which, depending on the pressure sensor 86, keeps the pressure in the line system 84 below a predefined maximum pressure.

[0062] Furthermore, a control unit 89 may be provided, which has at least two operating modes. In a first operating mode, the control unit 89 controls the valve units 82 jointly in the sense of a drive fluid supply or discharge. In a second operating mode, the valve units 82 are controlled individually or in subgroups in the sense of a drive fluid supply or discharge.

[0063] According to the invention, a valve unit 82 may be associated with each fluidically drivable motor drive unit 18. FIG. 10 shows such a combination of a fluidically drivable motor drive unit 18 with a valve unit 82 in neutral center position.

[0064] The valve unit 82 comprises a 5/3-way valve of known design and known function.

[0065] In the neutral center position of the valve unit 82, no drive fluid F is supplied to the motor drive unit 18, so that the motor drive unit 18 does not generate any input or output power.

[0066] The associated tensioning element 16 remains in its set position.

[0067] If the valve unit 82 is moved to one of the other two positions, drive fluid F may be supplied to the motor drive unit 18 by means of a line 90. This causes the motor drive unit 18 to rotate clockwise or counterclockwise. The rotation of the motor drive unit 18 may be reversed by changing the position of the valve unit 82 and the associated change in the flow direction of the drive fluid F.

[0068] Depending on the position of the valve unit 82, the motor drive unit 18 therefore generates an input force or an output force. The associated tensioning element 16 is thereby tightened and thus the stuffing box packing 42 is pressed against the superordinate assembly 10 or the tensioning element 16 is removed from the stuffing box packing 42 and thus loosened.

[0069] Depending on the position of the valve unit 82, at least one line 90 is vented into a shock absorber 92. In the present context, the term venting describes the discharge of the drive fluid F from the drive unit 18 by means of the line 90 connected thereto. The drive fluid F may be air, nitrogen and the like.