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HIGH PRESSURE SEAL MADE OF METALLIC LIKE MATERIAL

TECHNICAL FIELD OF THE INVENTION

The invention relate to high pressure systems with sealing ring and sealing groove, that can seal both fluid, gas and steam. The seal is meant to be used especially in systems for hydraulic, pneumatic and steams systems and for linear motions and also for a few slow rotary motions applications.

There are mainly only three different types of sealing rings working in sealing grooves, but also a sealing method named the sealing gap. The sealing gap method has no sealing ring and the result is a small leakage as the flow of fluid is restricted only by narrow walls with a few tusends of one millimeter between. To be able to make new great applications and products possible and to make it possible to seal without using the sealing gap method even in very compact designs, is the new sealing ring and sealing grove a double acting and pressure balanced seal and also a seal that can work even when the sealing rings seal groove is leaning less than 90° from the surface the sealing ring is sealing against. The new sealing ring is not split and is when new, or old and worn, working the same way because the shape of the sealing rings cross sections is about unchanged after wear, and the sealing groove is also, when old and worn, keeping or improving its shape so that good sealing performance is possible both when new and when old and worn. The friction forces of the new sealing ring is low because the sealing rings cross section is very small and practically not possible to deform by fluid pressure acting on the sealing rings surfaces or from forces coming from contact pressures between the sealing ring and surfaces around it. The invention with metallic or metallic like material has a cross section shape or form that is shown in fig. 1. The size and the shape or form of the sealing rings cross section makes the seal both double acting, pressure balanced and easy to twist or bend and because of that is it easy to mount the sealing ring in the sealing groove. A sealing ring that is double acting can seal in two pressure drop directions. A double acting sealing ring is also single acting in two pressure drop directions. A sealing ring that is pressure balanced on one part of the lengths of the sealing ring has the same pressure acting on both inner and outer side of the surface length that is pressure balanced. Metallic or metallic like material is used in this invention. One necessary material characteristic is that the material must have almost no compression form change which means that the material after being deformed under long time is springing back to its dimensions, form shape, size, as before being deformed. Seals with polymeric material have a high and bad permanent compression change in its cross section but have one advantage as it can accept that the sealing rings grove is leaning less than 90° towards the surface the sealing is sealing against. That because the sealing rings polymeric material can change its form, shape, or size easily or instant and a lot compared with this inventions metallic like material with a cross section that practically not can be deformed or changed in its form, shape or size. The cross section of the invention with a metallic like material can practically only twist and bend its cross section in circumferential direction, when it changes its diameter. The ability to twist, bend for a sealing ring using metallic like material is changing dramatically with cross section dimensions, as the force trying to deform the sealing ring is changing direct proportional to size or pressure but the cross sections ability to deform is changing much faster with dimension change. When designing seals with metallic like material is it, valuable to use a rule of thumb by using the formula. shown in fig.2.

The formula E*W*H7D [Nm] shows that W and especially H must be low to get a sealing ring that has ability to twist and bend its cross section enough.

Fig. 3 is showing how the cross section must be able to twist in two different directions, when the angel between the surface the seal is sealing against and the side surface of the seal grove is below 90°. In the new invention of a sealing ring is the side surface of the sealing ring first of all conic and can also be shorter than the total thickness of the sealing ring, See fig.1 :3 and 4 To produce the conic surface is easy as the cross section can be twisted enough and produced plane, and than able to springing back to a conical surface.

TECHNICAL BACKGUND

Hydraulic, pneumatic and steam system with sealing rings for fluid, gas and steam has a wide range of sealing needs that sometime is critical for the size of the system, function, lifetime and also for the total cost for the system and for ability to recover energy.

In compact valves for control of flow or pressure and for sealing of pistons in pumps and motors is the sealing gap method often used because of small size but the leakage is high and can sometimes be acceptable but often will the leakage problem be solved with extra valves for low or no leakage, but is also leading to other negative problems, that has to be solved. The normally dominating seals of polymeric material are seldom used in very compact components, for sealing at high pressures. Mainly and very often is the size to big and sometimes is also the reason, poor sealing function. The other two used types of sealing rings in sealing grooves is mainly of the material steel or the like and one of them has a sealing ring with a split and extra ability to change diameter when the temperature can be high and changing. That type of seal is totally dominating as piston seal in internal combustion engines and piston compressors. In compact high pressure systems like hydraulic is the split sealing ring very seldom used, mainly because of to high leakage.

Sealing rings of metallic or metallic like material with no split or closed split is 2015 much unknown and seldom used. In the market is today one type of piston seal used in high pressure hydraulic motors for high turning moment and low rotation speed. The sealing has a curved contact surface working against the bore surface. The width of the sealing rings contact surface is very narrow and the contact pressure is extremely high and the risk for high wear and short life is obvious. The curved contact surface is however making it possible to have the seal grove and the surface the sealing ring is sealing against, less than 90° degrees. As the degree of leaning is changing over the piston stroke is the narrow contact surface also moving over the curved contact surface and the sealing ring is weared, and the wear tryes to change the curved contact surface on the sealing ring to something different and the curved piston ring is not wearing in but wearing out.

The curved contact surface of the sealing ring sealing against the cylindrical surface is also creating a fluid wedge that over a certain piston speed will try to form a fluid film like in hydrodynamic bearings. In hydraulic piston pumps and motors is however sometimes the stroke relatively short and the speed becomes low and the sealing ring speed is going down before stopping and after stopping before speeding up in the other direction.

Fig. 5 is showing how the contact position is moving on the curved sealing ring surface. The ability to accept leaning sealing grooves is in this sealing ring invention made possible as the sealing rings side surface and the grooves side surface can contact with variable angel. Another already known sealing ring working in a sealing groove has the same inventor Stig Stenlund as for the new invention. The old patent has number Sweden 82025.4-4. The old invention is also patented in other countrys. See Fig. 6 . The old patented seal cannot be double acting and is not pressure balanced in a safe way and can not practically be used when the sealing groove is leaning below 90° degrees to the surface the sealing ring is sealing against. W and H must be about or over 2 to 3 mm to make a self controlled sealing system with no contact between the sealing rings surface and the surface it is sealing against. The sealing ring must be stiff, and consequently will the sealing rings cross section twist very little. The result is however very low leakage and very low sealing ring friction. The new invention of a sealing ring can get the same or better seal function with a double acting sealing ring that is pressure balanced in a safe way, and have a cylinderic not conic contact surface that is much cheaper to produce. See fig. 7. The bad thing is that both the old and new seal with number over 150Nm, can not work with a leaning sealing groove, and that the "large" cross section is making it practically impossible to mount the sealing ring in a sealing groove made in one solid piece. When the sealing rings cross section is smaller and when W and H are around and below 1 mm, like in the new invention, is the sealing rings contact surface always very small and the sealing ring will be in contact with the surface it is sealing against all the time or already after a very low pressure drop over the sealing ring and also with practically no leakage. One conclusion is that a sealing ring with "large" cross section is possible to do with self control of a small gap and with a low leakage and low sealing ring friction. For a sealing ring with "small" cross section is a gap not possible. But on the other hand have full contact seals with "small" cross section the ability to be a almost perfect seal with practically no leakage, very low seal friction, and with so small size that the sealing gap method can be avoided and the seal ring can be mounted in extremely small sealing grooves and be a substitute for the sealing gap methods in valves and the like. SUMMERY OF THE INVENTION

The invention is based on the inventors at the time best knowledge of how the perfect sealing ring must be working when it is sealing high pressure fluid, gas or steam in hydraulic, pneumatic and steam system and in applications where there a small play, between the part wherein the sealing groove is placed and the surface the sealing ring is sealing against. With other words in sealing situations where the sealed surface also is a guiding surface or a bearing surface. The new invention of a sealing ring in a sealing groove is able to replace the sealing gap method with a sealing ring and sealing groove about the same in size and friction, but with a leakage close to zero.

The new sealing invention is able to seal flow during long time of use and high pressure and also against surfaces that is too rough to be used by other polymeric types of sealing rings. The friction force of the sealing ring is also low at start and also at high speed of motion. The new sealing ring is not using hydrodynamic creation of fluid film at speed over a speed limit and is instead more or less always working with contact between the sealing ring and the surface it is sealing against, and by that working with practically zero leakage. The rule of thumb formula EWH ³ D with number below 5-6 is a sealing ring mat is so slender that it only can have its contact surface in full contact with the surface it is sealing against and that already at such a low pressure limits as a few bars. If on the other hand the rule of thumb number is over 150 is the sealing ring surface not in contact but is forming a self controlled gap with a very small distance between the sealing ring and the surface it is trying to seal against. The result is a low leakage flow and also low seal friction because the friction is coming from the fluid and mainly dependent of the viscosity of the fluid and the speed of motion. The difference in seal friction between "number under 5 and over 150" is low, and because of that is sealing rings with a rule of thumb number around and below 5 practically always a better choice. Everything but seal friction is better and safer for a number below 5. Sealing rings with rule of thumb number between 6 to 150 is not function safe and shall not be used. When the cross section is around or below the rule of thumb number 5 Nm is the sealing rings contact surface practically always in contact with the surface it is sealing against which means that the contact surface between the sealing ring and the sealing must be able to work with a sealing groove that is leaning below 90° degrees. In fig. 8A; 8B; 8C; 8D is shown different pressure balancing methods between the sealing ring and the sealing rings groove. In fig. 9 shows how the pressure in two directions is acting on the sealing ring. In fig. 10 shows how not balanced pressure is acting on the sealing ring.

Balanced pressure is not acting on the sealing ring and the result is that only unbalanced pressure is acting on the sealing ring. In fig. 11 shows how the not balanced pressures is pushing the sealing ring in one direction to the surface it is sealing against and not balanced pressures in the other direction is pushing the sealing ring side surface against the side wall of the sealing groove. When two parts of the sealing rings surface is hitting the sealing groove or the surface it is sealing against is two or more contact pressure areas created see fig. 11. One contact pressure areas is between the sealing ring and the surface the sealing ring is sealing against. Se fig.12 if the sealing ring is moving up and down in the sealing grove creates a friction force (Ρ*μ) between the sealing ring and one side wall of the sealing grove, and the contact pressure on the sealing ring will change and so will also the sealing rings friction against the surface it is sealing against Here named the sealing friction. The direction of movement for the sealing ring will change the size of the sealing friction, and at the same time is the contact pressure between the sealing ring and the side wall of the sealing groove changed. With a coefficient of friction for a steel-steel combination of about 0,2 is it a guarantee for good safe function to make the two unbalanced areas about the same in size and lengths.

Important is that friction forces not can open up the two contact areas so that a leakage starts. The form or shape of the sealing rings cross section is the main thing that is controlling that the sealing ring always has a sealing contact in two directions. To make it safe must the sealing grove have a side wall that is without chamfer or roundings close to the sealing rings contact area. In this invention is it important that only the shape or form of the sealing rings cross section is controlling the sealing function and not the form or shape of the sealing groove. With rule of thumb number around and under 5 is the

dimensions for the cross section very small. The width W is perhaps below 1 mm to 2 mm, and the thickness H is around and under 0,5mm. The balancing grove see fig. 13(2)in the sealing ring is about 0,5mm in width and the lengths of the unbalanced area that is sealing against the surface it is sealing against, here named sealing length is around and below 0,5 mm, and because of that is the leakage and the sealing friction at the same time very small. The sealing ring is so slender so it can be mounted in a sealing groove with 1 mm to 2 mm in width. The markets are asking for many different things and there are no other seals then this new invention of a seal that can meet most of what the market is asking for. Long life with low leakage is in this invention the result of two good things. One very important thing is that the normal material in the sealing ring is tempered steel with a surface hardness of about 700 Vickers.

The surface can also be even more wear resistant if it has a thin hard layer of for instant Balenite C, or the like on the sealing rings contact surfaces. Another very important thing for making the wear low is making the contact pressure between the sealing ring and the surface it is sealing against as low as possible. In the new invention is the contact pressure for the sealing ring acting on two surfaces, one before and one after the balancing groove, very low. The total size of the contacting force is only the result of the unbalanced pressure pushing the sealing ring forwards to the surface it is sealing against. The unbalanced pressure that is pushing the sealing ring against the sealing grooves side wall is in this invention chosen to be one relatively high force that hear also is trying to twist the sealing rings cross section with the result that the contacting pressures before and after the balancing groove is going to be more even, without that the total force pushing the sealing ring towards the surface it is sealing against is changed and that is resulting in a contact pressure on the sealing rings contacting surface is less than 50% of the pressure that the sealing ring has to seal. Compared with a steal sealing ring with curved contact surface, see fig. 5 is the contact pressure for the new invention less than 50% of the sealed pressure instead of several time higher contact pressures for a curved contact surface with very narrow contact. When this inventions sealing ring is sealing against the surface it is sealing against is the sealing rings contact surface worn to get the same form as of the surface it is sealing against. The sealing rings surface is then formed to a straight line and not a curved line. See fig.12. Conclusion the sealing ring is keeping its form and good sealing function even after it is worn after long time of use. The type of surface the sealing ring is sealing against is important for wear

resistance. Material, surface roughness, type of roughness, hardness,

temperature coefficient, are all very important. As steal and aluminum is dominating are steal seals for steal applications and aluminum seal for

aluminum applications covering almost all applications. For steal applications are a hard sealing ring and a soft steal surface to seal against good for low wear. If the steal surface the sealing ring is sealing against is hard is it very important that surface roughness is low. The lowest wear of the sealing ring is obtained when the sealing ring is very hard and the surface the sealing ring is sealing against not is hard and with a plateau surface, with very fine not rough surface on the plane tops on the plateaus. For aluminum applications is it not possible to make the aluminum material in the sealing ring hard enough. The sealing rings of aluminum is relatively soft and the wear resistance can be much better if the sealing ring is coated with a thin layer of, as one example, Balenite C or like that. If the sealing ring of aluminum, coated or not coated, has to be sealing against an aluminum surface that is hard must that surface be very smooth and practically not be wearing the sealing ring of aluminum. Long seal life with low leakage has always bin a must. Long time market dominance for polymeric seals has made it acceptable to ask for and pay for good surfaces that always is absolutely needed for polymeric seals.

In this invention can now relatively rougher surface be accepted and be used. Grinding, honing and roller burnishing methods is not the only methods that can be used, but also fine turning and other fine chip cutting or surface compressing methods. The new invention is up to here explained as a double active seal, but fig. 13 is showing how the same double pressure balanced sealing ring is changed to single active sealing ring. The differens is now that the surface nr 3 is a supporting surface and the pressure to the balancing grove nr. 2 is coming from pressure in the sealed fluid, gas or steam through a grove nr. 7 in the supporting surface that it the same time is changed from a potential sealing surface to only a supporting surface. The sealing ring at zero pressure can from start be in contact with the surface it is sealing against or have a small play so it needs a small pressure drop to get in contact and get a zero or practically zero leakage. Se fig. 14 showing how flow (Q) is changing when the pressure fall (Δρ) over the sealing ring is increasing. To have a sealing ring that is closing at a very low pressure drop is a good choice and it is making mounting simpler and sealing friction lower and also many other things. BRIEF DESCRIPTION OF THE DRAWING

The sealing ring and the sealing grove that, here is described before in principle, will now be described in more detail, with reference to the appended drawing Fig. 1 to Fig. 14. The drawing is exaggerated to better explain different functions distinctive character.

DETAILED DESCRIPTON In the following description is pointed out that the invention has both important embodiment that always is in the invention and always is the same and necessary and also alternative things that is improving the seal function in special applications. Fig. 1.

Shows that the form of the cross section of the sealing ring is principle the same both when the sealing surface is sealing against a surface that is on the sealed rings outside or on the sealing rings inside. The sealing ring that is sealing with its outside contact surface in named piston seal, as the contact surface is outside and is the sealing rings sealing surface. The sealing ring that is sealing with its inside contact surface is named a rod seal and can seal against a rod that is inside the sealing ring. Everything said here about the sealing rings and the sealing groves principal function is the same for both piston and rod seal. Fig. 2.

Shows that the rule of thumb formula is informing how the cross section of the sealing ring can be twisted to be able to work efficient or safe when the sealing ring and the sealing grove is leaning outside 90° degrees to the surface the sealing ring is sealing against. The formula has three dimensions and one material capability number. As seen in the fig. 2 is the W and H maximum dimensions for the sealing rings cross section. D is the sealing rings diameter. E is the materials, coefficient of elasticity. If the formula has number below about 5 and over about 150Nm is it safe to use. Below about 5 Nm is the sealing ring slender and can work with a small leaning seal groove, common for applications type piston for pumps and motors, used in hydraulic systems. Below rule of thumb number 5 is it also possible to mount the sealing ring in a sealing grove in one solid piece and the sealing ring can be enough deformed without permanent deformation. Under about 5 is the sealing ring with a small play even after a small pressure drop at, over the sealing ring, in contact with the surface it is sealing against, and the leakage is close to zero.

Rule of thumb number between about 5 to 150 is not functional safe and not recommended. Rule of thumb number over 150 for a seal cross section can not work with leaning sealing grove or be mounted in sealing groves, without that the grooves can be split in two parts. Unlike for rule of thumb number around and below 5 is the sealing rings with number around 150 and higher for its contact surface not in contact with the surface it is sealing against but the cross section is self controlled to become a conical sealing gap that has extremely small gap at the end when the pressure drop is high. Like explained before will the leakage and the seal friction be small, for rule of thumb number over 150 but a number below around 5 is preferred as it is safer pressure balanced and with low or zero leakage and low seal cross section.

Fig. 3.

Shows that if the seal grove is leaning outside 90° degrees is the sealing ring forced to twist in two different directions at the same time and that can easily be allowed when the rule of thumb number is below 5. Between rule of thumb number around 5 to 150 is it not functional safe. Over 150 is the cross section so stiff that the sealing ring practically not can twist and work as a seal in a safety way if the sealing grove is leaning.

Fig. 4.

Shows that in this invention is the sealing ring pressure balanced in two direction. The pressure that is pushing the sealing ring against the side wall of the sealing grove can as explained in fig. 8 be designed in many different ways. The sealing ring is always with its contact surface close to or contacting the surface it is sealing against.

With rule of thumb number aboutl 50 and higher is the cross section twisting very little and the leakage flow is going through one small but conical convergent self controlled sealing gap that is close to the surface it is sealing against.

With rule of thumb number about 5 or lower is the sealing rings contact surface mostly in contact with the surface it is sealing against. The ability to work in a leaning sealing grove is obtained between the sealing rings side surface contacting the sealing groves side wall, close to the sealing rings contact surface contacting the surface it is sealing against. The contact surface between the sealing ring and the sealing groove is narrow in width and is situated where the unbalanced pressures begin as acting to both push the sealing ring against the side wall of the seal groove and also to even out the contact pressure on the sealing rings surfaces before and after the sealing rings pressure balancing grove so that the lowest contact pressure will be more than 60 percent of the highest contact pressure.

Fig. 5.

Shows how the sealing ring on, a since long know seal type with a curved contact surface is contacting the surface it is sealing against. If the leaning is changing is also the narrow contact surface moving so that the wear is acting on a narrow but wider contact surface on the sealing ring.

Fig. 6.

Shows the cross section of another older patent with the same inventor as for this invention. The sealing ring is only single acting and the pressure balancing is unsafe and the sealing ring is not possible to mount in a sealing grove that is in one solid piece. Fig. 7.

Shows that a sealing ring with cross section over the rule of thumb number 150 can works like the old patent but is double acting and with a safe pressure balancing, and with the sealing rings contact surface cylindrical and not conical. Fig. 8A;8B;8C and 8D

Shows that pressure balancing of the sealing ring towards the sealing groves side wall can be designed in many ways. Fig. 8A; Fig. 8C; and Fig; 8D are based on balancing by making the side surface of the sealing ring conical. Two of them Fig. 8B and Fig. 8C are pressure balanced by making the conical side surface shorter. Fig. 8C is the preferred pressure balancing design and a combination of Fig. 8 A and Fig. 8B and used and preferred in all types of applications expect some types with very fast change in pressure, direction and speed wherein fluid between the sealing rings side surface and sealing grooves side wall is lowering the friction between the sealing ring and the sealing groves side wall, and by that lower the wear and frictions force between the sealing ring and the sealing groove. Fig. 9.

Shows how the sealing ring is pushed from all sides by the pressure in used pressure medium (fluid, gas and steam) Fig. 10.

Shows how the sealing ring is pushed by showing only unbalanced pressures. The total force from only unbalanced is the same as for all pressures acting on the sealing ring Fig. 11.

Shows how the total force from unbalanced pressures on the sealing ring are pushing the sealing ring against the surface, it is sealing against and the sealing groves side wall and shows how the total force is balanced by contact pressures on contacting surfaces. The contact surface between the sealing rings side surface and the side wall of the sealing groove is closed and by that is leakage flow stopped and leakage flow zero. The contact surface between the sealing ring and the surface it is sealing against is the same as the contact surface of the sealing ring. The total unbalanced force acting on the sealing ring can not be specified as it is dependent of the form or shape of the sealing rings cross section and of the fluid, gas or steam used, but can be maximum be as high as the pressure acting on the hole sealing length. See fig. 13 (4). The average contact pressure on the sealing rings contact surfaces is giving the same totally force as the unbalanced pressure acting to push the sealing ring against the surface it is sealing against. As the contact surface of the sealing ring is larger than the surface that is limited by the sealing rings sealing lengths is the contact pressure in the contacting area on the sealing ring about 50 percent or lower of the sealed pressure acting on the sealing ring. The contact pressure on the sealing ring can also be much lower if the pressure drop over the sealing lengths is falling linear over the sealing lengths like what it will do when there is a leakage flow, even if the flow is very small. The contact pressure will then be only around 25 percent. 50 percent and down to 25 percent is reached when the sealing lengths is about 0,35 mm, the balancing grove 0,5mm and the supporting lengths is 0,35 mm , in a sealing ring with a width of totally 1 ,2 mm. The contact pressure of the sealing ring acting against the surface it is sealing against can be very uneven but when the contact pressure is changing from lowest to highest shall the lowest contact pressure be higher than 60% of the highest contact pressure. Fig. 12.

Shows how movements of the sealing ring out or in to the sealing grove will create a friction force (Έ*μ) going in direction in or out of the sealing groove as the friction force always is acting opposite to the movement direction. The

5 contact force (F) must be pressure balanced so that sealing ring can move in or out of the sealing groove and not be locked to the sealing groove and by that changing the contact pressure of the sealing ring to take over the high forces needed to be guiding the piston or the rod. One good thing with balancing the friction force (F) is to make the force low but the force (F) must be the same or l o higher than the unbalanced force that is needed to even out the contact pressure before and after the balancing groove.

Fig. 13.

Shows how the double acting sealing ring can be changed to be a single acting sealing ring. The double acting sealing ring to the left has a contact surface that

15 start with the sealing lengths, (4) and thereafter is situated the balancing groove (2), and thereafter is situated another sealing lengths (4). The balancing is working with a hole (2) between the balancing groove and the other side of sealing ring (1) that always has the same pressure and no contact with the bottom of the sealing groove. The single acting sealing ring to the right has like

20 the double acting sealing ring first a sealing lengths (4) then the balancing

groove (2), but the second sealing lengths is replaced with a lengths named the supporting surface lengths (3) that has a groove in the supporting contacting surface after the balancing groove (7) that is letting the balancing groove have the same pressure as is acting on the opposite contacting side of the sealing ring

25 (1). With other words the double acting sealing ring is changed to a single acting sealing ring only by taking away the hole (2) to the balancing groove and replace it with a grove in the supporting surface (7) going from the high pressure side to the balancing groove.

Fig. 14.

30 Shows how the sealing ring with a rule of thumb number 5 or lower can have a small play and how that play starts and ends a leakage flow already after a small pressure drop over the sealing ring.

The rule of thumb number E* W*HVD is only used as a tool to be able to simpler explain how the size and form of the cross section starts to change, in a

35 stable way, the sealing rings ability to work with leaning sealing grooves, or be mounted in sealing grooves in one solid piece, or always be in contact with the surface it is sealing against, or never be in contact with the surface it is sealing against but is self controlled to be very close resulting in low leakage and low sealing friction. Rule of thumb number higher than 5 Nm and below 150 Nm

40 can be working very well but the margin to bad function is going down. Number 5 Nm and 150 Nm is only a simple indication and not a sharp limit