Seal and system with a seal

Abstract

The present invention relates to a seal and a system with two mutually rotating components and a seal.

Description

The present invention relates to a seal and to a system having two mutually rotating components and a seal.Systems of the type mentioned at the beginning are sealed in order to prevent media from escaping in an uncontrolled manner at the boundaries between the rotating and stationary component. In this case, seals are used. Seals may be either in the form of a single seal or as gaskets. A packing is a plurality of individual seals (also called packing rings) arranged one behind the other in the axial direction.From U.S. Pat. No. 7,040,627 B1 and U.S. Pat. No. 7,178,806 B1, two seals for such systems are known. U.S. Pat. No. 6,305,693 B1 discloses a seal for a system having a sealing ring which is arranged on a shaft and is pressed against a sealing surface in the axial direction by compression springs. Further seals are known from EP 4 006 354 A1, U.S. Pat. No. 3,402,937, DE 699 736 C and CN 105971924 A.The solutions known from the prior art are unsatisfactory in particular with regard to their long-term sealing effect. It was therefore the object of the invention to improve the sealing effect of seals for systems with two components rotating relative to one another.The solution to this object is a seal according to claim 1.The seal according to the invention is suitable for sealing between two components rotating relative to one another. These components are either a shaft and a stator or an axis and a rotor. A shaft is a member that rotates. An axis, on the other hand, does not rotate. The global rotation, for example in a module or a machine installation, is considered here. A relative rotation takes place between the shaft and the stator. A relative rotation also takes place between the axis and the rotor. The shaft and the axle are usually cylindrical, often elongated, components.The seal has a main ring and two side rings. These rings each have a central through bore for the axis or the shaft and are arranged one behind the other along a main axis X of the seal. The main ring is arranged between the side rings. However, it is also possible here for the rings to partially overlap. The main axis X is simultaneously the axis of rotation of the shaft or of the rotor.Each of the side rings rests on the one hand in a sealing manner on the main ring and on the other hand has a sealing point for sealing with respect to the stator or the rotor. The main ring has a sealing point for sealing with respect to the axle or the shaft. The sealing points can each be a sealing line or a sealing surface. In both cases, the sealing point extends circularly around the main axis X.The rings are subjected to a spring force in such a way that the side rings are pushed apart in the axial direction and the main ring is pushed in the direction of the shaft or axis. In other words, the rings are acted upon by a spring force in such a way that they are pressed at their sealing points against the respective sealing partner. The spring force can be exerted by at least one spring element. Accordingly, at least one spring element is preferably provided, which presses the side rings apart in the axial direction and the main ring in the direction of the shaft or axis.The inventors have recognized that in this way a substantially simple and secure seal can be provided. The rings can each be designed in such a way that they perform the sealing function intended to them reliably and permanently. The spring force exerted on the side rings also makes possible readjustment during wear.The seal ensures that substances such as a lubricant are prevented from flowing along the shaft or the axis.The side rings and the main ring preferably bear against one another on surfaces which each run perpendicularly to the main axis X. In this way, the sealing effect between the side rings and the main ring is the greatest.The seal can be pressed between two contact surfaces when used as intended. In this case, the main ring or a part thereof is preferably compressed in the axial direction. The main ring and the side rings then lie adjacent to one another in the axial direction in a sealing manner. If the side rings are gradually pushed apart due to wear and due to the spring force (so-called readjustment), the main ring relaxes over time without the sealing points between the main ring and the side rings losing sealing effect. In this readjustment, no relative movement of the main ring on the one hand and the shaft or axis on the other hand is required, which was often necessary in the prior art and led to an uneven readjustment on account of the material of the main ring. Materials with a high coefficient of friction remain attached to the shaft / axis during such a relative movement.A further individualization of the individual components can be achieved in that the main ring is multi-part and comprises a radially inner core ring and a radially outer outer ring. The side rings then preferably each lie on the one hand sealingly against the core ring and on the other hand they have the sealing point for sealing with respect to the stator or the rotor. While the core ring preferably provides the sealing point with respect to the shaft or axle on the one hand and with respect to the side rings on the other hand, the outer ring can (co-)act, for example, a prestress and thus a spring force of the core ring in the direction of the shaft or axle.According to the invention, it is provided that the main ring, in particular the core ring, does not execute any relative movement with respect to the shaft or the axle. In the case of the shaft, the main ring / core ring therefore rotates with it, and in the case of the axis, the main ring / core ring is static. As a result, in particular the sealing point between the main ring / core ring and the shaft / axis is held tightly, since each relative movement involves the risk of leakage. The main ring, in particular the core ring, can be fastened to the shaft or the axle in a form-fitting or materially integral manner. Both types of connection bring about a particularly secure positioning of the core ring / main ring on the shaft or axle. However, it is also possible for the main ring to be fastened to the shaft or the axle in a frictionally locking manner. In this case, the main ring is preferably at least partially high in friction (high coefficient of friction) and the side rings are low in friction (low coefficient of friction) relative thereto. In this case, in particular, the core ring is high in friction and the side rings are low in friction. The outer ring can also be less friction than the core ring, since it is sufficient if only the core ring is produced from a material with high friction. Since both the main ring / core ring and the side rings provide sealing points, the above-mentioned selection of the coefficients of friction ensures that the main ring does not perform any relative movement with respect to the shaft or axis, but the side rings can perform relative movements with respect to the rotor or the stator.The main ring, in particular the core ring, is at least partially formed from an elastomer. Elastomers are friction-rich, i.e. have a high coefficient of friction. The side rings preferably consist of a PTFE-based material, a PEEK-based material or a carbon-based material. These materials have low coefficients of friction. Here, "based" means that the material either consists of the relevant substance or comprises it and other substances, for example fibers. Carbon-based materials (also referred to as carbon materials) are understood in particular to mean materials which contain, as main constituent, different carbon forms such as cokes, graphites, carbon blacks or else carbon fibers.As mentioned, the outer ring does not have to have a high coefficient of friction and can therefore consist of a PTFE-based material, a PEEK-based material or a brass-based material. In order to allow the outer ring to effect a prestress of the core ring, the outer ring is preferably composed of a material having a modulus of elasticity <10 000 MPa. A material with a low modulus of elasticity causes the spring forces to have a stronger effect.In advantageous refinements, the main ring, in particular the core ring, is produced undersize with respect to the axis or the shaft. The central through bore of the main ring is then smaller in the relaxed state than the outer diameter of the shaft or axle. There is then an interference fit between the main ring and the shaft or axle after assembly. This procedure is particularly suitable when the main ring or the core ring is arranged on the shaft or axle in a force-fit manner. The press fit reinforces the sealing point with respect to the shaft / axis.In advantageous refinements, the main ring is mirror-symmetrical, in particular on a plane perpendicular to the main axis X and in particular in the mounted state. This configuration makes it possible to configure the side rings in the same construction and arrange them in mirror-image on the main ring. The construction of the side rings of the same construction makes their production more cost-effective.As mentioned above, the side rings are forced apart by an axially acting spring force and the main ring is forced against the shaft or axle by a radially acting spring force. These two spring forces can be brought about by different spring elements. However, the construction of the seal according to the invention can be simplified by configuring and arranging a spring element such that it produces both an axial and a radial force. In advantageous refinements, it is therefore provided that the main ring, in particular the outer ring, has at least one oblique outer circumferential surface which faces a side ring. The oblique outer circumferential surface can be used to split or deflect a force. An outer circumferential surface is considered to be oblique in particular when it extends at an angle >0° and <90° to the main axis X. The oblique outer circumferential surface is preferably part of a lateral surface of a cone which is substantially spanned around the main axis X and substantially has a base surface perpendicular to the main axis X. Because of the undersize configuration, slight deviations can occur in this case, which are acceptable, however. For a uniform force distribution, it is particularly advantageous if the main ring has two oblique outer circumferential surfaces, each of which faces one of the side rings.The spring element is preferably a tubular spring. The tube spring may be disposed between the inclined outer circumferential surface and the side ring. In this case, it is supported on the inclined outer circumferential surface on the one hand and on the side ring on the other hand. As a result, it exerts both an axial force on the side ring and a radial force on the main ring. In the case of two inclined outer circumferential surfaces, preferably two tubular springs are provided as spring elements, which are each arranged between one of the inclined outer circumferential surfaces and the side ring facing it. This leads to a uniform force distribution, by means of which tilting of the main ring can be avoided.Depending on how obliquely the outer circumferential surface is formed, a different force distribution takes place into the axial spring force and the radial spring force. Very small or very large angles have proven to be inadequate and disadvantageous with regard to the force distribution. The oblique outer circumferential surface therefore preferably forms an angle between 15° and 85° with the main axis X. The choice of angle also depends on the other properties of the seal. If the main ring is connected to the shaft or axle in a materially bonded or positive-locking manner, for example, no substantial radial spring force is required. In this case, the angle can be made quite large, for example between 60° and 85°. If, on the other hand, a material is used for the side rings which is rather subject to severe wear, the axial spring force can be reduced by selecting a small angle, for example between 5° and 30°. An angle between 30° and 60° represents a good compromise between both properties.For easier assembly of the side rings, it is preferably provided that at least one side ring is multi-part. For example, the side ring can be constructed from a plurality of ring segments, wherein the ring segments can preferably be connected to one another in a force-fitting or form-fitting manner, for example by screwing or by a puzzle connection.The seal according to the invention is constructed in such a way that a relative movement can take place between the side rings on the one hand and the stator or rotor on the other hand. In order to ensure that the relative movement takes place in the region of the sealing points of the side rings and that the side rings do not rotate with the rotor or remain stationary with the stator, it is provided in advantageous refinements that at least one side ring is positively engaged with the main ring, in particular the core ring, in the circumferential direction. It is not absolutely necessary here for the side ring and the main ring or core ring to allow no relative rotation at all. In particular, a positive engagement can be present, which, however, allows a certain amount of play. Since the shaft or the rotor rotates only in one direction and does not undergo a change of direction in most applications, the side ring then permanently abuts on a flank on the main ring during the rotation, whereas an opposite flank has a gap in the circumferential direction with respect to the main ring or the core ring.For the positive fit between the main ring and the side ring, it is provided in advantageous refinements that the main ring has at least one axial protrusion which protrudes into an axial receptacle of one of the side rings, or vice versa. This brings about a positive connection in the circumferential direction, which, as explained above, prevents an undesired relative rotation between the main ring and the side ring. Particularly advantageous with regard to mikatability, force transmission and service life has proven to be the shape of a Reuleaux triangle for the axial projection and the axial receptacle. A particularly effective form-fit connection is achieved if the axial projection and the axial receptacle each run around the through bore. However, a plurality of individual compounds are also possible.In advantageous refinements, the outer ring has a gap in the circumferential direction. This initially facilitates the mounting of the outer ring on the core ring. In addition, it enables the outer ring to act as a spring element. For this purpose, in advantageous refinements, the outer ring is produced undersize with respect to the core ring. In the relaxed state, the outer ring has an inner diameter which is smaller than the outer diameter of the core ring, in particular of the core ring in the mounted and / or relaxed state.The core ring is preferably one-piece and interrupted in the circumferential direction and has two ends which can be connected to one another in a form-fitting manner. As a result, the core ring can be closed in the circumferential direction. A one-piece embodiment facilitates assembly, since two components that fit one another do not have to be provided. Since the core ring is often made of an elastomer and is thereby flexible, the core ring can also be easily mounted if it is one piece. The ends may include an acceptable deviation of the core ring from the mirror symmetric configuration. In the assembled state, the core ring is nevertheless preferably mirror-symmetrical.The object of the invention is also achieved by a system with two mutually rotating components and a seal according to the above description. The components are in particular a shaft and a stator or else an axis and a rotor. The stator or the rotor forms in the system two contact surfaces against which one of the side rings sealingly abuts. The sealing point of the side rings is then located between the side ring and the associated, i.e. directly adjacent, contact surface. The sealing point of the main ring or core ring is accordingly formed between the main ring / core ring and the shaft or the axle.In advantageous refinements, the seal is pressed between the contact surfaces. In this case, in particular the main ring or core ring is compressed in the axial direction. The main ring or core ring and the side rings then lie adjacent to one another in the axial direction in a sealing manner. If the side rings are gradually forced apart as a result of increasing wear, the main ring or the core ring relaxes over time without the sealing point between the main ring or core ring and side ring losing sealing effect.In advantageous refinements, the rotor or the stator forms a housing for the seal or has such a housing. As a result, the seal can be compressed and pressed in a predefined manner. For this purpose, the housing preferably has an inner length measured along the main axis X which is smaller than the total length of the seal measured along the main axis X (outer side of one side ring to outer side of the other side ring) in the relaxed state. The housing can furthermore have an inlet for a sealing or purging gas.If the seal has an inclined outer circumferential surface and if a tubular spring is arranged on this outer circumferential surface, the tubular spring is expanded outwards and prestressed during the pressing of the seal between the contact surfaces. As a result, the tubular spring, when used as intended, causes an even greater radial spring force on the main ring or the core ring and an axial spring force on the side rings.The invention is illustrated and explained by way of example with reference to the drawings. The figures listed below are illustrated in the drawings: FIG. 1 shows a system with a seal according to a first embodiment in a sectional view, FIG. 1a shows the detail A of FIG. 1, FIG. 2 is an exploded perspective view of the seal of FIG. 1 ; and FIG. 3 shows a system with a seal according to a second embodiment in a sectional view.The system 100 shown in FIG. 1 includes a centrally located shaft 110 and a stator 120. The stator 120 is disposed around the shaft 110. In intended use, the shaft 110 rotates about its major axis X. The stator 120 does not rotate. Thus, shaft 110 and stator 120 rotate relative to each other. The stator 120 comprises a housing 122 for a seal 10. In the embodiment shown here, the inlet 124 is closed by a retractable plug and can be opened if necessary if additional sealing gas is to be connected. This allows additional safety to be achieved.The construction of the seal 10 can be seen from FIG. 1 a. The seal 10 comprises a main ring 20 and two side rings 50. the main ring 20 in turn has a core ring 30 and an outer ring 40. The main ring 20 and the side rings 50 are arranged one behind the other along the main axis X, wherein the main ring 20 is arranged between the side rings 50. The outer ring 40 is disposed radially outward of the core ring 30. As can be seen from FIG. 2, the core ring 30 has a through bore 34 and the side rings each have a through bore 54. The shaft 110 passes through the through-holes 34, 54 in the system 100.It can be seen in FIG. 1 a that each side ring 50 rests on the one hand in a sealing manner on the main ring 20, namely on its core ring 30, and on the other hand has a sealing point 56 for sealing with respect to the stator 120. The sealing point 56 is located on an axial outer side 52 of the respective side ring 50, and the core ring 30 has a sealing point 36 on its radially inner circumferential surface 32 for sealing with respect to the shaft 110. The outer ring rests on a radially outer circumferential surface 33 of the core ring 30.The core ring 30 is made of an elastomer in this embodiment. It is furthermore one-piece and interrupted in the circumferential direction and has two ends 35 a, 35 bwhich can be connected to one another in a form-fitting manner (see FIG. 2 ). The inner diameter of the core ring 30, i.e. the diameter of the inner circumferential surface 32, is smaller than an outer diameter D of the shaft 110 in the relaxed state. When the core ring 30 is disposed on the shaft 110, an interference fit is provided between these components. As a result, the core ring 30 is firmly held on the shaft 110.The main ring 20 is constructed mirror-symmetrically on a plane perpendicular to the main axis X. The side rings 50 are structurally identical, but are arranged in mirror-imaged fashion on the main ring 20. As can be seen from FIG. 2, the side rings 50 are multi-part. Both side rings 50 consist of two parts each, which are screwed together for assembly.In the embodiment shown here, the side rings 50 consist of a PTFE-based material. This material is low in friction compared to the elastomeric material of the core ring 30. If the shaft 110 rotates when used as intended, the core ring 30 attached to the shaft 110 in a frictional manner is also rotated. Since the core ring 30 and the side rings 50 bear firmly against one another, the side rings 50 are also co-rotated. Due to the low coefficient of friction of the side rings 50, they rotate at their sealing points 56 with respect to the stator 120.In the embodiment shown here, the outer ring 40 consists of a PEEK-based material. As can be seen from FIG. 2, the outer ring 40 is in one piece and has a gap 42 in the circumferential direction. The inner diameter of the outer ring 40 is smaller than the outer diameter of the core ring 30 in the assembled state in which the core ring 30 is attached to the shaft 110. For assembly, the outer ring 40 is therefore stretched, which is possible due to the gap 42. Then, the outer ring 40 is placed on the outside of the core ring 30. Due to the dimensioning, the outer ring 40 cannot fully deform back into the relaxed state and as a result a radially inwardly directed force acts on the core ring 30. This results in the core ring 30 being pressed even more firmly onto the shaft 110.The outer ring 40 has two oblique outer surfaces 44. The inclined outer circumferential surfaces 44 each extend at an angle λ of approximately 45° relative to the main axis X (see FIG. 1 ). Each of the outer circumferential surfaces 44 faces a side ring 50. As a result, a groove running around the main axis X is formed in each case between an outer circumferential surface 44 and a side ring 50.In each of these grooves, a hose spring 62 is arranged as a spring element 60. The tubular springs 62 are an endless helical spring which extends in a circular manner. The tube springs 62 are dimensioned such that they must be expanded so that they can be arranged in the grooves. The tubular springs 62 thereby primarily cause a radially inwardly directed spring force on the outer ring 40 and thereby on the core ring 30, the core ring 30 thereby being pressed further onto the shaft 110. Due to the inclined outer circumferential surfaces 44, a part of the inwardly directed spring force of the tubular springs 62 is deflected and acts on the side rings 50 in the axial direction. The side rings 50 are thereby pushed apart in the axial direction and in particular pressed against an inner side of the housing 122. As a result, the sealing effect at the sealing points 56 is reinforced.The housing 122 has a free space in the interior, which has a length L in the axial direction. The two side rings 50 and the core ring 30 have an overall length along the main axis X which is greater than the length L in the relaxed state. If the seal 10 is arranged in the housing 122, the side rings 50 and the core ring 30 are therefore compressed in the axial direction. In particular, the core ring 30 is compressed due to its elastomeric properties. This also reinforces the sealing effect at the sealing points 56 and at the sealing points between the side rings 50 and the core ring 30.The core ring 30 has two axial projections 38 which have the shape of a Reuleaux triangle and run around the through-bore 34. The side rings 50 each have an axial receptacle 58, which likewise have the shape of a Reuleaux triangle and run around the through-bore 54. The axial projections 38 and the axial receptacles 58 are of complementary configuration. In the assembled state (see FIG. 1 ), the axial projections 38 each project into an axial receptacle 58, and the core ring 30 and the side rings 50 are connected to one another in a positive-locking manner in the circumferential direction in this way. This ensures that, when the shaft 120 rotates, the side rings 50 also rotate in addition to the core ring 30.FIG. 3 illustrates another embodiment of a system 100. In this embodiment, the system 100 includes an axle 130 and a rotor 140. The centrally arranged axis 130 is static here and the rotor 140 arranged around the axis 130 rotates when used as intended.Inside the rotor 140 is arranged a seal 10 comprising a main ring 20 and two side rings 50. The main ring 20 is one-piece in this embodiment. However, like the core ring 30 of the first embodiment, it is interrupted in the circumferential direction and has two complementary ends which can be connected to one another in a form-fitting manner. In this embodiment, the main ring 20 is connected to the axle 130 in a form-fit and force-fit manner by means of screws 22. For this purpose, the axle 130 has a groove 132 running in the circumferential direction, in which the main ring 20 is arranged.The force-fit and form-fit connection of the main ring 20 and the axle 130 ensures that the main ring 20 is also static.The main ring 20 is designed mirror-symmetrically on a plane perpendicular to the main axis X. The side rings 50 are of identical design and each bear sealingly against the main ring 20. The side rings 50 also each rest against sealing points 56 on an inner side of the rotor 140. To reinforce the sealing effect at these sealing points 56, a spring element 60 in the form of a compression spring 64 is provided. The compression spring 64 acts directly on the side rings 50 and presses these apart in the axial direction.The seal 10 ensures that substances such as a lubricant can flow along the shaft 110 or the axis 130.List of reference characters10 Seal 20 Main ring 22 Screw 30 Core ring 32 Inner circumferential surface 33 Outer circumferential surface 34 Through bore 35 a, 35 bEnd 36 Sealing point 38 Axial projection 40 Outer ring 42 Gap 44 Outer circumferential surface 50 Side ring 52 Outer side 54 Through bore 56 Sealing point 58 Axial receptacle 60 Spring element 62 Hose spring 64 Compression spring 100 System 110 Shaft 112 Casing 120 Stator 122 Housing 124 Inlet 130 Axis 132 Groove 140 Rotor D Diameter L Length X Main axis λ AngleReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedU.S. Pat. No. 7,040,627 B1

[0003] U.S. Pat. No. 7,178,806 B1

[0003] U.S. Pat. No. 6,305,693 B1

[0003] EP 4 006 354 A1

[0003] U.S. Pat. No. 3,402,937

[0003] DE 699 736 C

[0003] CN 105971924 A

[0003]

Claims

Seal for sealing between two components rotating relative to one another, in particular between a shaft and a stator or between an axle and a rotor, wherein the seal comprises a main ring and two side rings, wherein the rings each have a central through-bore for the axle or the shaft and are arranged one behind the other along a main axis X, wherein the main ring is arranged between the side rings, wherein each side ring, on the one hand, sealingly abuts the main ring and, on the other hand, has a sealing point for sealing with respect to the stator or the rotor, wherein the main ring has a sealing point for sealing with respect to the axle or the shaft, and wherein the rings are acted on by a spring force in such a way that the side rings are pressed apart in the axial direction and the main ring is pressed in the direction of the shaft or axle.Seal according to Claim 1, characterized in that the main ring is multipart and comprises a radially inner core ring and a radially outer outer ring, the side rings each bearing, on the one hand, sealingly against the core ring and, on the other hand, having a sealing point for sealing with respect to the stator or the rotor.Seal according to Claim 1 or 2, characterized in that the main ring, in particular the core ring, is fastened to the shaft or the axle in a positive-locking or materially integral manner.Seal according to Claim 1 or 2, characterized in that the main ring is at least partially friction-rich and the side rings are low-friction, wherein in particular the core ring is friction-rich and the side rings are low-friction.Seal according to one of the preceding claims, characterized in that the main ring, in particular the core ring, consists at least partially of an elastomer and / or the side rings consist of a PTFE-based material, a PEEK-based material or a carbon-based material and / or the outer ring consists of a PTFE-based material, a PEEK-based material or a brass-based material.Seal according to one of the preceding claims, characterized in that the main ring, in particular the core ring, is produced undersize with respect to the axis or the shaft and is therefore seated in a force-fitting manner on the axis or shaft.Seal according to one of the preceding claims, characterized in that the main ring is mirror-symmetrical, in particular on a plane perpendicular to the main axis X, and in that the side rings are arranged identically but in mirror-symmetrical fashion.Seal according to one of the preceding claims, characterized in that the main ring, in particular the outer ring, has at least one oblique outer circumferential surface which faces a side ring, wherein preferably two oblique outer circumferential surfaces are provided which each face one of the side rings.Seal according to one of the preceding claims, characterized in that the spring element is a tubular spring which is arranged between the oblique outer circumferential surface and the side ring, wherein preferably two tubular springs are provided as spring elements, which are each arranged between one of the oblique outer circumferential surfaces and the side ring facing it, wherein the oblique outer circumferential surface forms an angle of between 15° and 75° with the main axis X.Seal according to one of the preceding claims, characterized in that at least one side ring is multi-part.Seal according to one of the preceding claims, characterized in that at least one side ring is positively engaged with the main ring, in particular the core ring, in the circumferential direction, wherein the main ring has at least one axial projection which projects into an axial receptacle of the side ring, or vice versa, wherein the axial projection and the axial receptacle preferably have the shape of a Reuleaux triangle and / or run around the through bore.Seal according to one of the preceding claims, characterized in that the outer ring has a gap in the circumferential direction.Seal according to one of the preceding claims, characterized in that the main ring and / or the core ring is one-piece and interrupted in the circumferential direction and has two ends which can be connected to one another in a positive-locking manner.System having two components rotating relative to one another, in particular a shaft and a stator or an axle and a rotor, and a seal according to one of the preceding claims, wherein the stator or the rotor forms two contact surfaces, on each of which one of the side rings sealingly bears, wherein the seal is preferably pressed between the contact surfaces.System according to claim 14, characterised in that the stator or the rotor forms a housing for the seal and has an inlet for a sealing or flushing gas.

Images