DE1095603B - Gap seal for housing lead-throughs of rotating shafts with automatic adjustment of the width of the sealing gap - Google Patents

Description

The invention relates to a gap seal for housing bushings rotating shafts of centrifugal machines, in which a small amount of the medium to be sealed is constantly being fed through the throttling Sealing gap emerges.

Such gap seals have become known that are exclusively spring-loaded. Such designs However, due to the fixed spring tension, they can only change with a very specific one Set the inlet pressure automatically so that even if there is only a slight deviation, compliance a constant gap width is not guaranteed. When this pressure drops, there is there is an increasing risk of the two sealing parts tarnishing, which inevitably leads to increased wear is. In certain systems, the inlet pressure is load-dependent and fluctuates depending on the between widely spaced limit values z. B. with so-called feedback pumps for the condensate of high pressure preheaters with uncontrolled extraction steam from a turbine stage be heated.

Furthermore, such seals are known in which the springs are replaced by a resilient bellows are or by flexible rings that form an annular space, or by a cylinder, in which an annular piston slides. These statements can only apply to a very specific one Set the inlet pressure automatically. Furthermore, gap seals have also become known, although they are for abandonment have to ensure a finite gap width even with changing operating conditions. The automatic adjustment of the gap width is impaired in these, however, by the fact that the sealing gap narrows in the direction of flow and its width at all points due to the shift the moving part is affected.

Ultimately, purely mechanical face seals are known in which similar means for generating the sealing force can be used. However, these are not gap seals, but about friction-prone sliding seals, which cannot be compared with pure gap seals.

In order to avoid all the disadvantages described in the known designs, a gap seal for housing feedthroughs of rotating shafts, especially on centrifugal machines, with a Sealing gap between the radial sealing surfaces of a stationary, connected to the housing Part and a rotating axially movable part with the shaft, the end faces of the axially movable part for automatic adjustment of the width of the sealing gap, at least partially the pressure of the medium to be sealed acts on the gap seal for the housing bushings

rotating waves

with automatic adjustment of the width

of the sealing gap

Applicant:
Klein, Schanzlin & Becker

Corporation,
Frankenthal (Palatinate), Johann-Klein-Str. 4/9

Dipl.-Ing. Klaus Wellhöner, Frankenthal (Palatinate),
has been manned as an inventor

are proposed according to the invention that the axially movable part as rotating with the shaft on a flange which carries a sealing surface sleeve is formed, which is to be sealed with its Space facing end with the formation of an axial annular gap in a bore with the housing tightly connected, the other sealing surface-bearing part protrudes and its flange on the inflow side of the sealing gap is recessed so that it connects with a corresponding recess the opposite end face of the fixed part forms an annular space that extends over the axial Annular gap communicates with the space to be sealed, while the other end of the sleeve in another annular space formed by a cap firmly connected to the shaft and sealingly immersed is acted upon by the pressure of the space to be sealed via longitudinal channels in the sleeve.

By means of these measures according to the invention, a safe, automatic setting is achieved even when there are changes Operating conditions guaranteed without the disadvantages of the known gap seals cling, can occur.

In order to create a clear equilibrium, the gap seal according to the invention the outer diameter of the sleeve at the outer end immersed in the cap is greater than it Outside diameter at its inner end facing the space to be sealed. Furthermore is the inside diameter of the annular space equal to the outer diameter of the sleeve at its inner end and the outer diameter of the annular space is greater than the outer diameter of the sleeve at its outer end.

009 679/301

The diameter ratios of the annular space selected in this way ensure that the in this space prevailing, dependent on the gap width and acting in the sense of a widening of the sealing gap Pressure exerts a force on the sleeve which, at the desired gap width, corresponds to that on the end faces of the Sleeve acting compressive forces holds the balance, as will be explained in more detail below.

Said cap is axially immovable on the shaft with slotted or two-part rings attached and sealed against her by sealing rings. The rotary motion is made by this cap her opposite longitudinally movable pins on the said sleeve and its flange-like approach from the Wave communicated. Opposite the sleeve, the cap is preferably round with the aid of a sealing ring Cross-section sealed in a longitudinally movable manner. These latter measures ensure proper attachment and low-friction sealing.

Fig. 1 shows in section the gap seal according to the ao Invention with the formed between a fixed part on the housing and an axially movable sleeve Sealing gap;

Fig. 2 to 4 show thematically the change in the gap width of the sealing gap under the influence of occurring pressures, which on the ring surfaces of the axially movable, selected according to their size Act on the sleeve.

In Fig. 1, the stationary part 2 surrounding the axially movable sleeve 4 is on the pump housing 1, which carries the one seal 5, fastened with screws 3. The axially movable sleeve 4, the flange-like Part 6 carries the other, circumferential sealing surface 7, is on the shaft 8, sliding on a key 9, Mounted so as to be longitudinally displaceable and takes a cap during its rotation by means of a driving pin 10 11 with. At the same time, this cap 11 by the slotted ring 12 on the one hand and by the two-part Retaining ring 13 and a mounting ring 14 on the other hand with the interposition of two packing rings 15 and a spacer ring 16 fixed in their position on the shaft. Between the axially movable sleeve 4 and the cap 11 is a round rubber seal 17 for sealing the latter relative to the sleeve 4 brought in. Between the sleeve 4 and which it around- * 5 Providing part 2 fixed to the housing, there is an annular gap 18 through which there is a constant flow Cross-section. Between the sleeve 4 and the shaft 8 are pressurized by the internal pressure of the machine Channels 19.

In the explanation of Figs. 2 to 4 it is assumed that the radial gap between the sealing surface 7 of the movable sealing sleeve 4 and the sealing surface 5 of the fixed part 2 is initially infinitely small. At a pressure P ₁ in the space to be sealed ο of the machine and a relaxation _{pressure P 0} in the outer space d , the pressures P ₁ , P ₂ and P ₃ shown schematically in Fig. 2 prevail on the surfaces in the spaces α and c as well as in the sealing gap , of which P ₂ and P _{3 are} variable. These are counteracted by pressures P ₄ and P ₅ in spaces b and d. The pressure in space b is the same as in space a. The size of the effective areas on the sleeve 4 on which the pressures act is determined by their inner and outer diameters and is chosen so that initially the sum of the forces directed to the left is greater than the sum of the forces directed to the right, so that the resulting force R moves the axially movable sleeve 4 to the left (Fig. 2). This opens the gap and the two sealing surfaces 5 and 7 move away from one another. A certain amount of liquid now passes through this opened gap and flows in from space a. In this case, however, as the flow rate increases, the throttle loss in the annular gap 18 formed by the sealing sleeve 4 and by the part 2 surrounding it increases. This means that in the space c between the axial gap 18 and the radial gap 5, 7 an intermediate pressure P ₂ <C _{P 1 is} established and the mean pressure F ₃ in the sealing gap also drops. As a result, the forces P ₂ F ₂ and P ₃ P _s acting to the left on the sealing sleeve become smaller, so that the equilibrium is established at a certain gap width (Fig. 3). It is now

If the sealing gap widens too much due to any circumstances, the Gap flowing loss and thus also, the throttling in the axial gap 18 so large that the resulting Force pushes the sealing sleeve back into equilibrium to the right (Fig. 4). By cheap choice the proportions of the effective areas can be derived from a simple equilibrium consideration of the movable Didh sleeve 4 set the force necessary to move the sealing sleeve to the left which overcomes the frictional resistance on the round rubber seal 17 and on the feather key 9.

Claims (6)

Patent claims: 1. Gap seal for housing feedthroughs of rotating shafts, especially on centrifugal machines, with a sealing gap that runs between the radial sealing surfaces of a stationary part connected to the housing and an axially movable part rotating with the shaft, the end faces of the axially movable part for automatic adjustment the width of the sealing gap are at least partially acted upon by the pressure of the medium to be sealed, characterized in that the axially movable part is designed as a sleeve (4) rotating with the shaft and carrying a sealing surface (7) on a flange (6), which with its end facing the space (a) to be sealed protrudes into a bore of the part (2) bearing the other sealing surface (5) and the flange (6) on the The inflow side of the sealing gap is recessed so that it is cut out together with a corresponding recess g on the opposite end face of the stationary part (2) forms an annular space (c) which is connected to the space to be sealed (α) via the axial annular gap, while the other end of the sleeve (4) is in one of one with the shaft firmly connected cap (11) formed further annular space (b) immersed sealingly, which is acted upon by the pressure of the space to be sealed via longitudinal channels (19) in the sleeve (4). 2. Gap seal according to claim 1, characterized in that the outer diameter (D ₂ ) of the sleeve (4) at the outer end dipping into the cap (11) is greater than its outer diameter (D ₁ ) at its space to be sealed (a) facing inner end (Fig. 2 to 4). 3. Gap seal according to claim 2, characterized in that the inner diameter of the annular space (c) is equal to the outer diameter (D ₁ ) of the Sleeve (4) is at its inner end, while the outer diameter (D ₃ ) of the annular space (c) is greater than the outer diameter (D ₂ ) of the sleeve (4) at its outer end. 4. gap seal according to claim 1 to 3, characterized in that the cap (11) on the shaft (8) with slotted or two-part rings (12, 13) fixed axially immovable and opposite it is sealed by sealing rings (15). 5. gap seal according to claim 4, characterized ge ίο indicates that the cap (11) through her opposite longitudinally displaceable driver pins (10) over the sleeve (4) and its flange-like extension (6) the rotational movement of the shaft (8) is communicated. 6. gap seal according to claim 4 and 5, characterized in that the cap (11) with the aid of a Sealing ring (17) of preferably round cross-section with respect to the sleeve (4) sealed in a longitudinally movable manner is. Considered publications:
German Patent Nos. 451 079, 524 515;
French Patent Nos. 983 992, 1 034 254; British Patent Nos. 632 957, 671165;
U.S. Patent No. 2,672,357;
German utility model No. 1 683 969;
German patent application B 25885 XII / 47 f
(announced on February 25, 1954). 1 sheet of drawings 009 679/301 12.60