GB2062133A - Axial Sealing Device for High Fluid Pressures - Google Patents

Abstract

An axial sealing device has a sealing member 36 mounted between a stationary part 23 of a machine and a rotating part 28 of the machine. A static sealing ring 60 is located between a surface 57 of the stationary machine part 23 and a corresponding surface 53 of the sealing member 36. To provide at least partial pressure equalisation on the sealing member 36, this member 36 has one or more steps 53, 54 formed in it and supplied with axial fluid pressure so that axial pressure is exerted on the sealing member 36 in the direction tending to close the sealing gap 50 between a surface 48 of the sealing member 36 and a surface 49 of the rotating machine part 28, an oppositely directed axial pressure acting on the sealing member 36 at the sealing gap 50. <IMAGE>

Description

SPECIFICATION A Hydro Dynamic Axial Sealing Device for the Sealing of High Fluid Pressure The present invention pertains to a hydrodynamic sealing device with at least one sealing member, designed particularly for the sealing of high fluid pressure between a stationary and rotating machine component, or two rotating components especially in the case of hydraulic machinery, and in those cases where the sealing member is statically sealed by, for example, one or more units of polymer, or some other elastic material.

As axial sealings for hydraulic machines, and for the sealing of high hydraulic-oil pressure, there are various types of sealing gaskets, so called 0rings, i.e., sealing rings usually made from polymer with prestressing by a closed ring of an elastic material, e.g. an O-ring.

The problem with these known types of gasket rings and their installation in various machines is that they are not pressure-equalised. The gasket ring is installed in such a manner that the hydraulic pressure is transmitted to certain parts of the sealing surface which results in a great amount of friction and the development of a lot of heat as a result. This in turn is damaging for the polymer material and deformations (extrusion damage) easily occur. In order to avoid these deformations to some degree, small gaps must be made, for example, on the rotating part which is to be sealed. Furthermore, the O-ring must constantly apply pressure on the gasket ring so that the sealing function can be maintained. Also, the sealing combination demands very small margins of tolerance, at the maximum equal to that of the prestressing of the O-ring.Because of its construction, the gasket ring is made to bear pressure which is unequally destributed across its sectional area, which results in wear. Another drawback is that rotation can occur between the gasket ring and the O-ring., whereby the O-ring is quickly destroyed and the sealing function is lost.

Through the effect of heat, because of the high losses, the subsidence of the O-ring can be considerable and even in this case the sealing function can be lost.

The aim of the present invention is to try to avoid the above-mentioned drawbacks and to provide a sealing device in which the surface pressure is reduced or totally eliminated between the sealing element and the opposite surface (sealed surface), or at least that part which is caused by hydraulic pressure. This is done by counter-balancing the sealing element, and the sealing device performs tolerantly against axial shifting, and comparatively large margins of tolerance can be used.

The invention is defined in claim 1 hereinafter.

The invention will now be described in more detail, solely by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a principal section of a known axial sealing device of the type mentioned in the introduction, Fig. 2 shows, in enlarged form, a part FF2 with the inner sealing gasket as an integral part of the device, of Fig. 1, with the distribution of pressure, pressure pressure patterns, Fig. 2a is the resulting pressure-distribution diagram ------ pressure pattern ----for the gasket of to Fig 2, Fig. 3 is a section of a part of a hydraulic machine with an axial sealing device embodying the invention.

Fig. 4 shows, in enlargement, a part FF4 with an inner axial sealing flange, in the device of Fig.

3.

Fig. 5 is a general diagram of the relation between the distribution oil film pressure and the pressure differences at various broad sealing slits.

Fig. 6, 6a, 7, 7a, 8, 8a, 9, 9a, and 10 illustrate pressure distribution diagrams ---- pressure patterns ------ for various sealing gaps and the inner axial sealing flange of Fig. 4, Fig. 11 and 1 a illustrate an example of a wrongly shaped inner sealing flange with a pressure distribution ---- pressure patterns, Fig. 1 2 illustrates a variation of an inner axial sealing flange of a part FF4 in Fig. 4, Fig. 1 3 shows a portion of the axial sealing flange according to lines XIII -XIII in Fig. 12, Fig. 14 and 1 4a illustrates the pressure distribution diagram ------ pressure patterns for the sealing flange of Fig. 13, and Fig. 15 is an enlarged view of a part FF15 of the device in Fig. 3 with an outer axial sealing flange in the axial sealing device embodying the invention.

The object of the known axial sealing device, shown in Fig. 1 and 2, is that an inner and outer sealing gaskets 1 and 2 respectively built into a circular tracks 3 and 4 in the body 5 of a hydraulic machine having a cylinder block 6, and where each sealing gasket 1 and 2 respectively, is under static pressure from an O-ring 7 or 8, respectively, should reduce the stray flow which can occur between, on the one hand, plain vertical surfaces 9 and 10 on the body 5 and, on the other hand, vertical sealed surfaces 11 and 12, respectively, on an applied rotating distributor 14 which encircles a rotary axis 1 3. The cylinders of the hydraulic machine (not shown) receive an oil flow, or oil pressure, from a pressure source (not shown) to an inlet channel 1 5 and further to a circular, first, ring-shaped channel-part 1 6 in the body 5, connected with a circular, second, ringshaped channel 1 7 and then to a distribution channel 1 8 in the distributor 14. Through the rotation of the distributor 14, the oil is distributed from the distribution channel 1 8 to cylindrical inlet channels 1 9 (one shown) in the cylinder block 6, to be conveyed further to the cylinders.

The return of the oil from the cylinder takes place from channel 1 9 via drainage-channel 20 and discharge channel 21 in the distributor 14 and the body 5 respectively. When rotation occurs in the opposite direction in the hydraulic machine, the pressure oil enters channel 21 and is conveyed further to channel 20 and to the cylinders and the return oil, i.e. the drainage, takes place through channels 1 9, 18, 17-16 and 15.

In order to illustrate the distribution of pressure in, for example, the inner sealing gasket 1, reference is made to Figs. 2 and 2a with the pressure-distribution diagram --pressure patterns ---- TA2, TA3, T,,, TA4 and TAE. The aim of the known construction has been, at a suitable optimisation leakage and outer pressure, to reduce the oil leakage as much as possible and the oil pressure from a value P, on the highpressure side to a value P2 on the low-pressure side in the sealing-slit 22.

The pressure-patterns TA and TA2 show that the pressure conditions in radial direction to a good degree counterbalance each other. The pressure-pattern TA3 in axial direction on the reverse side of the sealing gasket 1 in the sealing slit 22 is constant along the whole of the width of the inner sealing gasket 1. However, the pressure between the inner sealing gasket 1 and the sealed surface 11, decreases from the high-pressure to the low-pressure side, see pressure-pattern TA4.

For the sake of clarity, the line of the pressurepattern has schematically been drawn linearly, but in reality it can deviate. This means, as Fig 2a, pressure-pattern TA5 shows, that the pressure force on the inner sealing gasket 1 increases from the high-pressure to the low pressure side, which in turn causes, as mentioned in the introduction, the total hydraulic pressure to transmit itself to certain parts of the sealing surface 11 and the inner sealing gasket 1 to be loaded unequally across its cross-section with high friction, wear, and a great development of heat as a result.

Another drawback is that an undesired rotation can occur between the inner sealing gasket 1 and the O-ring 7, whereby the O-ring is quickly destroyed and the sealing function is lost.

In the case of the outer sealing gasket 2, which in principle is installed in the same manner as the inner sealing gasket 1 , the drawbacks are the same as in the case of the latter.

In Fig. 3, which shows a cross-section of a hydraulic machine with an operational form of an axial sealing device in accordance with the invention, 23 shows the first machine part, namely a stationary connection flange with flowchannels 24 and 25 which are connected with flow-channels 26 and 27, respectively, in another machine part, namely a rotating distributor 28.

This distributor 28 with a rotation axis 29 is built into a stationary cylinder block 30 with plungers 31 (one shown) and cylinder-barrel (outlets) channels 32 (one shown). The plungers 31 work in a conventional way against an unshown cam which is connected up to the rear gable of the machine, 33, which is accordingly rotating and normally connected to that unit which is to be driven. The distributor 28, which is connected with the cylinder block 30 is axially steered by an axial roller 34 and via a finger 35 is connected to the rear gable 33 and thereby has the same speed as this.

In order to achieve sealing between the connection flange 23 and the distributor 28, two axial sealing devices are inserted in the form of inner and outer sealing flanges 36 and 37 respectively, which both have an elongate axial extension and which, with the help of tension pins 38 and 39, respectively, are secured against rotation relatively to the connection flange 23.

The outer axial sealing flange 37, the outer circular surface 40, as well as the smaller axial part of the outer surface 41 on the distributor 28 nearest the outer axial sealing flange 37 have clearances 42 and 43, respectively, from the cylinder block 30 in order to facilitate the drainage of the stray-flow. This stray flow passes through a drainage hole 44 and a channel 45 for return to the olltank. A displayed, circular, first, ring-shaped channel-part 46, in the distributor 28 is connected with a circular second ring-shaped channel-part 47 between the inner and outer axial sealing flange 36 and 37, respectively, in the connecting flange 23, and these together form a flow connection between the flow-channels 25 and 27.In the case of the normal rotation of the machine, the pressure oil is sent through the flow-channel 25 and further through channels 46-47 and 27 to the cylinder inlet (outlet) channel 32 to plunger 31.

The return of the oil for drainage then takes place through the flow-connections in channels 26 and 24. In the case of opposite rotation the reverse flow direction occurs, i.e. the pressure oil enters through channels 24 and 26 and the return oil (drainage) passes through channels 32, 27, 46- 47 and 25.

Fig. 4, which is a part-enlargement of Fig. 3, shows a clearer picture of the construction of the axial sealing flange 36, in this case, in which sealing is to be effected between the radial plain (vertical) surface, also called the sealing surface, 48 and the radial (vertical) sealed surface 49 on the distributor 28. For greater clarity, the sealing gap 50 between the said surfaces is somewhat enlarged in the drawing. The inner axial sealing flange 36 has on its outer circular surface two step-shaped ledges with radial plain-surfaces 51 and 52 and axial circular surfaces 53 and 54, respectively, which ledges, in reverse direction in relation to the sealed surface 49, are meant to co- ordinate with the corresponding step-shaped ledges with radial plain-surfaces 55 and 56 and axial circular surfaces 57 and 58, respectively, in the connection flange 23. Between surface 54 on the inner axial sealing flange 36 and the surface 58 on the connection flange 23 a circular, ring shaped space 59 is provided which gives an axial movement of the inner axial sealing flange 36 in the connection flange 23, and in this space is inserted a rectangular, or possibly a square plastic ring 60. A spring element is also provided in the form of a snap-ring 61 which is placed in a gap 62 between the surfaces 51 and 55 in order to give an initial prestressing of the inner axial sealing flange 36 against the sealed surface 49.

The static sealing does not need to be plastic ring 60, but may be exchanged for an O-ring possibly with support rings. The tension clip 38 is put into the connection flange 23 and with extension into a built-in track 63 in an inner axial sealing flange 36. Naturally, there could be another form of locking, with buttons, for example, on the inner axial sealing flange 36, which fits into a hole in the discharge flange 23. In the inner surface 64 of the inner axial sealing flange 36, a circular track 65 has been shaped.

The equation for the fluid-flow in a slit of varying width, b, on, for example, the inner axial sealing flange, 36, of the sealing member and various gap widths, h, give different pressure-patterns, see Fig. 5, Curve Iha shows the oil-film pressure in a narrow gap haf and curve lihb the pressure of the oil-film in a wide gap hb.

The following describes how totally. ar partly, pressure-balanced sealing member can be maintained at a fluid pressure p1 from the outside and with a lower fluid pressure p2 from the inside, i.e. the drainage side, of the inner axial sealing flange 36, and when a static sealing in the form of a plastic ring 60 is used. The inner axial sealing flange 36 is used in order to seal from both directions. This is in regard to the fact that in the case of opposite rotation of the hydraulic machine, the inside of the axial sealing flange 36, is the pressure side and the outside is the drainage side. The functioning is exactly the same. Furthermore, the rear gable 33 may be totally motionless and the connection flange 23 rotating, or both rotating without this affecting the method of operation.

Fig. 6 shows the pressure-distribution diagram -- pressure patterns-- for the device according to Fig. 4 and there the sealing gap 50 is even, i.e.

the openings at the beginning and end of the gap are h,=h2. For the sake of simplicity in the figure, the plastic ring 60 has been left out, and the width of the opening of the gap has been exaggerated.

When the fluid-pressures p1 and p2 on both sides of the inner axial sealing flange 36 are equal, the bow-shaped snap-ring 61 presses the axial sealing flange 36 against the sealing surface 49.

When the oil under pressure is switched on it flows into the gap 62, to the space 59 between the inner axial sealing flange 36 and the connection flange 23 and will press on the radial pressure surfaces 51 and 52 so that the inner axial sealing flange 36 is pressed against the sealing surface 49 on the distributor 28. The pressure works on the physical area A11+A12=A1.

and the pressure patterns viz. the power fields TB1 -T,, and TB2 - become rectangular.

The opposite effect occurs when oil presses against and into the sealing gap 50, between the inner sealing area (pressure-surface) 48 of the axial sealing flange 36 and the sealed surface of the distributor 49. The counter-pressure which is built up in this way, so-called bursting pressure, tends to open the sealing gap 50. The pressurepattern T93 is somewhat bow-shaped but almost triangular. A suitable preventive measure is to shape the sealing device so that the inner axial sealing flange 36 under the effect of the pressure is deformed so that the sealing gap 50 opens itself against the pressure. The resulting pressurepattern TB4 turns out as is shown in 6a, i.e. to a great degree a completely counter-balanced axial sealing flange 36 is obtained.With proper geometrical shaping of the surfaces 48 and 49 this is secured and the circular track 65 in the inner axial sealing flange 36 has an important function in this case, namely, by giving the inner axial sealing flange 36 a weak mid-section, 11, which has a certain relationship to the parts of the sectional areas and the weakness in the higher thinner part of the inner axial sealing flange 36, shown as 12 The radial forces on the inner axial sealing flange 36 from the oil pressure p1 on the outer surface 66 of the indicated sealing flange 66 and the surfaces 53 and 54, are shown as F1, F2 and F3, respectively.

Fig. 7 shows the pressure-patterns for a little ring-shaped sealing gap 67, somewhat deformed because of the movements in the weak mid section,11, caused by the forces F2 and F3 and where the measurements in the beginning and end of the gap are h3 and4, respectively, and where h3 > h4. Here the final pressure-pattern is in accordance with Fig. 7a, i.e. TB1+TB2+TB5=TB6 The inner axial sealing flange 36 will be shifted to the right.

Fig. 8 shows the pressure-pattern for a large ring-shaped sealing gap 68, somewhat deformed because of the same reason given for Fig. 7, and there the measurements in the beginning and the end of the slit are h5 and h6, respectively, and where h5 > h. The final relevant pressure-pattern is shown according to Fig. 8a, i.e.

TB1+TB2+TB,=TB8. The inner axial sealing flange 36 will be shifted to the left.

Fig. 9 shows pressure-patterns for a gap opening which something between that slit opening shown in Fig. 7 and Fig. 8. Through suitable choice of the pressure-pattern areas Y11+Y12=Y1 a definite sealing gap 69 is achieved, with openings h7 and h8 in the beginning and end of the gap, respectively, where the force equalisation takes place, i.e. the sum of the pressures =0 and areas Y2=Y1. The resulting pressure-pattern TB1+TB2+TBg=TB,O consists as Fig. 9a shows of two large triangular surfaces.

The sealing is thereby completely counterbalanced at a definite slit opening h7, hB. The snapring 61, in this case, has little significance.

If the surface Y2 should be greater than Y1, the sealing gap 69 opens and another pressurepattern TB7 applies, see Fig. 8, i.e. Y decreases.

The sealing gap 69 becomes so large that the resulting force on the inner axial sealing flange 36 is equal. The inner circular track 65 has thereby, as already mentioned, an important function in this context, namely, that the inner axial sealing flange 36 is self-regulating. If the surface Y2 should be somewhat smaller than the surface Y1, this means that the sealing slit 69 decreases and the pressure-pattern Te5, according to Fig. 7a is obtained, i.e. Y2 increases so that Y2=Y1.

Fig. 10 shows the case where the fluid pressure to the sealing gap, now shown as 70, increases from a value p1 to a value p3 and an output pressure now of value p4 which can be equal to p2. The pressure-patterns are here shown as T611, T512 and13. The pressure forces on the surfaces 66, 53, and 54 are shown in F4, F5 and F6 respectively, and the inner axial sealing flange 36 is deformed around the weak mid-section 11, in track 65 and the dimension of the gap, h9, in the beginning becomes smaller in relation to the dimension of the gap, h,0, in the end, i.e. a resultant pressure distribution similar to Fig. 7a is obtained. The sealing flange is shifted to the right, h10, increases.

A comparison: Fig. 10 Fig. 9 fluid pressure p3 > p1 gap h9 > h, gap h10 > h8 Even in this case self-regulation is obtained through the geometrical dimensioning so that the surface Y4 is equal to the surface (Y31+Y32) =Y3.

It follows, therefore, that the size of the sealing gap varies with the fluid pressure in such a way that the former is bigger at high rather than low pressure. Track 65, as earlier mentioned, has the task of giving the inner axial sealing flange 36 a weak mid-section, 11, and to make certain that the sealing surface 48 opens against the pressure through the radial pressure forces F1, F2, F3, alternatively F4, F5, F6 on the surfaces 66, 53, 54, so that a pressure-pattern of the form T13,T55, T97,T69 and T513 in Fig 7, 8, 9 and 10 is obtained.

If the opposite is the case the pressureequalisation will be uncertain as is shown in Fig.

11.

Accordingly, Fig. 11 shows an example of a less suitable sealing flange 71 without the earlier mentioned track 65. The sealing gap 72 has an opening h11 at fluid pressure p, and an opening h.2 on the drainage side with fluid pressure p5.

The pressure-pattern T514 at the sealing surface 49 accordingly, becomes unequal, as earlier described, because the pressure forces, according to the pressure-patterns Te1, Te2, and Te4 try to tip the sealing flange 71 in the wrong direction and the resulting pressure pattern will be as TB15 in Fig. 11 a shows. The result, hence, is higher pressure and imbalance and the sealing flange 71 is pushed strongly against the sealing surface 49 resulting in inconvenience in the form of heavy wear.

In the practical example of Fig. 4, the plastic ring 60 seals to the right, i.e. backwards in the space 59 and against the surfaces 54, 58, on the inner axial sealing flange 36 and connection flange 23, respectively. In the case of opposite rotation of the hydraulic machine the fluidpressure direction is reversed with inlet into the flow channel 24, whereby the pressure is obtained against the circular inner surface 64 in the inner axial sealing flange 36. In this case the fluid pressure comes up on the reverse side of the inner axial sealing flange 36, up through the reverse track 73, whereby the plastic ring 60 seals in the other direction in the space 59, i.e. to the left in the illustration and against the surfaces 53, 57, on the inner axial sealing flange 36, and the connection flange 23.

The fluid pressure on the inside of the sealing flange 36, besides causing forces in the track 65, also gives rise to forces which are directionally opposite to those forces FX, F2, and F3 which are shown in Figs. 7, 8, 9, and 10. The directionally opposite forces cause a deformation of the inner axial sealing flange 36, at the weak mid-section, 1,, so that the sealing gap opens in the direction of the pressure. Thereby, we obtain as a comparison: in the sealing gap 67, Fig 7 h4 > h3 in the sealing gap 68, Fig 8 h6 > h5 in the sealing gap 69, Fig 9 hB > h, in the sealing gap 70, Fig 10 h1o > hg The above has been proven to be correct through computer calculations.The sealing gap is, accordingly, always opened against the pressure direction and one obtains a complete, or partially, counter-balanced inner axial sealing flange 36, regardless of which direction the sealing should come from. The sealing device will perform tolerantly against axial shifting, and comparatively large margins of tolerance may be used.

It might be mentioned that the difference between the inlet and outlet-height of the opening of the gap is very small, in some cases about 10cm.

If the fluid pressure occurs only in one direction, as p1 in Fig. 4 shows, track 65 may be excluded. The geometrical design of the pressure surface A11, A12, in Fig. 6 will thereby be somewhat different. See the more detailed description for the outer axial sealing flange 37 according to Fig. 1 5.

Fig. 1 2 and 1 3 show a partly counter-balanced inner axial sealing flange 74 which is a variation of the totally counter-balanced inner axial sealing flange 36, according to Fig. 4. The plain circular radial surface 75, on the inner axial sealing flange 74, which should seal against the sealed surface 49 of the distributor 28, is equipped with two circular tracks 76 and 77. These tracks 76 and 77 are connected with each pressurised volume v1 and v2, respectively, on the outer and inner sides, respectively, of axial sealing flange 74 by two radial diametrically opposed tracks 78 and 79, respectively. Therefore, the pressure difference between track 76 and volume v1, and track 77 and volume v2 is zero.

Fig. 14 shows a variant of the inner axial sealing flange 74, the size of the pressure patterns Tei and T52 at areas A11 and A12(A11+A12=A1).

Area A1 and the pressure-pattern T516 show the counter-pressure on the area A2(A21+A22=A2) in the sealing flange 80. The resulting pressurepattern To17' see Fig. 1 4a, shows that the resultant power presses the axial sealing flange 74 against the sealed surface 49 as area A1 is greater than A2.

The sealing gap 80 becomes, in the partly counter-balanced inner axial flange 74, smaller than the sealing gap 69 in the totally counterbalanced inner axial sealing flange 36, according to Fig. 9 and, thereby, the leakage will be even smaller.

By changing the radial distance between the circular tracks 76 and 77, the degree of the pressure-equalisation will be changed. The relationship between the surfaces A21 and A22 can be changed and, thereby, also the pressure of the inner axial sealing flange 74 against the sealed surface 49. The numerals 81 to 88, inclusive, correspond to the earlier mentioned 51 to 54, inclusive, as well as 63 to 64, inclusive.

Fig. 1 5 which is a partial enlargement of Fig. 3, shows a more intricate construction of the outer sealing flange 37, in which sealing should occur between the plain radial (vertical) surface 89, and a sealed surface 90 on the distributor. The sealing slit is shown as 91. The outer axial sealing flange 37 has on its inner surface 92, a step-shaped down-turning with radial (vertical) surface 93 and axial (horizontal) surface 94. Between surface 94 on the outer axial sealing flange 37 and a circular inner track 95 in surface 96 on the connection flange 23, there is a circular ring-shaped space 97 which imparts an axial movement of the outer axial sealing flange 37 in the connection flange 23, and for static sealing in 97 a rectangular, or square, plastic ring 98 or O-ring is fitted.In the former case a springing-element is also used in the form of a snap-ring 99 placed in a circular space 100 between a radial (vertical) in-turning 101 in the connection flange 23 and reverse surface 102 on the outer axial sealing flange 37, in order to provide initial pre-stressing of the outer axial sealing flange 37 against the surface 90 on the distributor 28. The tension pin 39 is put into connection flange 23 and reaches a track 103 in the outer axial sealing flange 37, through which the latter is secured against rotation.

The outer surface of the outer axial sealing flange 37 is supplied with a somewhat smaller diameter surface 104 than the inner diameter 105 on the cylinder block 30 in order to give drainage to the outlet channel 106, (added in order to clarify the figure compared with Fig. 3).

The outer axial sealing flange 37 has also in surface 89, against sealed surface 90, a circular bevel 107 in order to provide a reserve oil chamber 108 in the case of drainage.

In the sealing gap 91, with gap-opening h13, the incoming pressure is p1 and exit pressure is p6 at the gap opening hr4. The oil pressure p1 exists even in the opening between the radial (vertical) surface 93 of the outer axial sealing flange 37 and the radial (vertical) surface 109 of the connection flange, and, further partly reduced in spaces 97 and 100, which means that, analogous with the discussion of the inner axial sealing flange 36, the outer axial sealing flange 37 through suitable dimensioning becomes totally or partly counterbalanced for sealing against the sealed surface 90.The outer axial sealing flange 37 is also dimensioned in such a way that the pressure forces F7, and F6 on the surfaces 92 and 94, respectively of the sealing flange affect the sealing flange in such a way that the dimensions of the gap-opening become h13 > h14 which is favourable for the resultant pressure-pattern.

The outer axial sealing flange 37 does not have to be equipped with a track of the type 65 or 87 as in the case of the inner axial sealing flange 36, as the outer axial sealing flange 37 is exposed to pressure from one direction and only in the case of one the one of the rotation directions of the hydraulic machine. In the case of the opposite direction of rotation the channel 46--47 a 7 is the drainage channel at low pressure.

For those who are experienced in this field, it is obvious that the outer axial sealing flange 37 can be designed at totally or partly counterbalanced, in a way analogous to the discussion on the inner axial sealing flange 36, without requiring a more detailed description. Furthermore, it is obvious that outer axial sealing flange 37 can be made with circular tracks 76,77 and radial tracks 78 and 79 as in Fig. 12 and 13, if this is thought to be suitable in certain situations.

In order to avoid confusion in the illustrations of Figs. 6-11 and 14, 15, the hydraulic pressures on the axial surfaces of the sealing flange have been indicated with force arrows F1 .. F8, instead of partial pressure forces on the complete surfaces. Furthermore the sealing element 60 in Figs. 6-11 and 14, has been left out.

The advantages which can be expected from the axial sealing device, in which there is at least one sealing member, can be summarised as follows: (1) The sealing member is totally, or partly, pressure-equalised which results in low outer pressure and low friction, and, therefore, very little wear.

(2) Through the design of the sealing member the loading of the edges is reduced.

(3) The sealing element and thereby also the static sealing -- the plastic ring -- and the snap ring can not rotate relatively to the first machinepart which means less friction, development of heat and wear. The sealing function is not lost.

(4) The sealing member is made of metal and, therefore, tolerates a large gap between the sealed surfaces without being damaged or misshaped.

(5) Through the axial mobility of the sealing member the sealing slit around the whole periphory is maintained even if deformations in the hydraulic machine, because of outer loads, should occur. The sealing member is therefore flexible.

(6) Relatively large margins of tolerance in installation are allowed.

Claims (14)

Claims

1. An axial sealing device with at least one sealing member, for sealing high fluid pressure between a stationary and a rotary machine-part or two rotary machine parts, where in the sealing member is provided with one or more step-shaped ledges and are so arranged that axial fluid pressure is supplied to the ledge-formed radial surfaces producing an axial pressure on the sealing member in a direction against a sealing gap between the sealing member and a sealing surface on a machine-part which is to be sealed, the said pressure being compensated for by a directionally opposite axial pressure on the sealing member, the directionally opposite axially pressure coming from the fluid pressure which operates in the indicated sealing gap, whereby by suitable choice of size of the pressure surfaces, a totally, or partly, pressure-equalised sealing member is obtained.

2. An axial sealing device according to claim 1, wherein the sealing member includes a sealing flange extending in the direction, which is axially mobile in or on a machine-part.

3. An axial sealing device according to claim 1 or 2, wherein the sealing organ is prestressed towards the sealed surface by a ring-shaped spring element.

4. An axial sealing device according to claim 3, wherein an elastic pin and a track in the sealing member secure the sealing member against rotation, so that the ring-shaped spring element and static sealing means are secured against rotation.

5. An axial sealing device according to any one of claims 1 to 5, wherein the or each step-shaped ledge on, or in the sealing member interacts with a respective step-shaped ledge in a machine-part.

6. An axial sealing device according to claim 5, wherein a circular, ring-shaped space is formed between one ledge in the said machine-part and a ledge on the sealing member, in which a static sealing element is placed for sealing, either axially reversed between two ledges or axially forward between two other ledges.

7. An axial sealing device according to claim 5 or 6, wherein the or each step-shaped ledge in the said machine-part is an out-turning and the or each step-shaped ledge on the sealing member is a down-turning on the outer-surface of the sealing member.

8. An axial sealing device according to claim 5 or 6, wherein a step-shaped ledge on the said machine-part is a down-turning and a stepshaped ledge on the sealing member is an outturning on its inner surface.

9. An axial sealing device according to any one of claims 1 to 7, wherein that surface on the sealing member which is turned towards the sealing slit is furnished with one or more circular tracks each of which by way of a radial track is connected with a respective pressurised volume.'

1 0. An axial sealing device according to any preceding claim, wherein the sealing member is equipped with an inner circular track which gives the sealing member a weak mid-section, as a result of which the fluid pressure which acts on the sealing member affects its function in such a manner that the width of the sealing gap on the pressure side becomes somewhat larger than its height on the drainage side, i.e. the gap opens itself against the pressure side.

11. An axial sealing device according to claim 10, wherein the sealing member has one or more outer axial pressure surfaces against which the indicated fluid pressure acts or by the indicated fluid pressure acting radially from the opposite direction, i.e. from the inner circular surface of the sealing member whereby a deformation of the weak mid-section is obtained with that function which is given in claim 10, and independently of the direction of rotation of the hydraulic machine.

12. An axial sealing device according to any one of claims 1 to 9, wherein there are two sealing members respectively in the form of an inner sealing flange and an outer sealing flange, and the inner sealing flange is designed for sealing from the outside to the inside, or vice versa, and the outer sealing flange is designed for sealing from only one side.

13. An axial sealing device according to claim 12, wherein the outer sealing flange is pressure loaded in such a way against its inner surfaces that the said pressure produces forces which causes such deformation that the sealing slit of the sealing flange opens itself against the pressure.

14. An axial sealing device according to claim 1 and substantially as described hereinbefore with reference to Figs. 3, 4 and 1 5 or to any one of Figs.6,7,8,9,10,11,12and 14Ofthe accompanying drawings.