SEALING UNIT

Description

Technical field of the invention

[0001] The invention relates to a sealing unit with at least one radial passage for conveying a fluid from a stationary machine part to a rotating machine part, in particular for use on a machine tool or on accessories for machine tools, such as driven tools, and to a method for sealing a radial passage of such a sealing unit. State of the art

[0002] Devices and arrangements for transferring a fluid from a stationary machine part to a rotating machine part, also known as rotary distributors, are generally known in the prior art. The fluid intended for use in the invention is typically a coolant or a lubricant.

[0003] The essential components of a rotary distributor, which in a specific design is also called a rotary union, are the stator and the rotor. The stator is usually rigidly connected to a stationary machine part. In contrast, the rotor is typically mounted on the stator so that it can rotate relative to it. Both the stator and the rotor have channels for fluid transfer. The transition from the (stationary) stator to the (rotating) rotor is usually achieved via circumferential grooves (also called annular channels) formed on the stator and / or the rotor. In addition to the aforementioned essential components, the rotor and stator, rotary distributors generally have sealing arrangements that ensure the necessary pressure-tight seal between the stator and the rotor. Furthermore, a bearing arrangement is usually provided to allow the relative movement between the rotor and the stator.

[0004] Such a rotary distributor is shown in US 2014 / 0028016 A1.

[0005] The rotary union shown, which forms part of a fluid line, is specifically designed for use with a tire inflation system for vehicles. It facilitates the transfer of a pressurized fluid, such as air. It is based on technical solutions exclusively intended for tire inflation systems on vehicles.

[0006] This rotary union comprises a first housing section, a rotor, and a second housing section, a stator, as well as a first annular and elastic sealing element and a second sealing element, which is also annular and elastic. The stator is connected to a stationary machine part, and the rotor to another rotating machine part.

[0007] The rotary feedthrough has at least one radially oriented fluid line which is guided through the rotor and the stator, with body sections of the rotor and the stator forming part of the fluid line.

[0008] The stator, the rotor and the two sealing elements are arranged coaxially to a system axis.

[0009] The rotor has a ring-shaped form, preferably with a rectangular cross-section. A radially oriented rib, an annular sealing projection, projects from the outer surface of the rotor, positioned centrally.

[0010] The stator is formed from two profiled ring disks, which are abutting each other and detachably connected to form the stator housing. The abutting ring disks have mutually aligned recesses, so that in the assembled state a radially inwardly directed groove is formed into which the annular sealing projection of the rotor protrudes.

[0011] The side surfaces of this sealing projection each form a rotor sealing surface.

[0012] Opposite each rotor sealing surface, one of the two ring-shaped elastic sealing elements is arranged in the relevant side surface of the stator groove and is positioned there with its base section firmly and sealingly.

[0013] Starting from the base section, each sealing element features a lip section projecting at an angle, forming a V-shaped cross-section. The outward-facing surface of the lip section, which in the assembled state faces the rotor sealing surface, is equipped with a sealing friction pad.

[0014] During the assembly of the individual parts and subassemblies of the rotary feedthrough, the lip section of each sealing element is pre-tensioned by a lateral force exerted on the lip section by the respective rotor sealing surface via the sealing friction pad. This ultimately means that the sealing surface of each sealing element is constantly pressed against the respective rotor sealing surface under pre-tension, which significantly increases the friction typically encountered in rotating seals.

[0015] Each sealing element, including its lip sections, is elastic. When the pressure in the tire inflation system increases, the pressure in the rotary union also increases, which in turn acts on the lip sections. This causes the sealing friction pad provided on each lip section to be pressed more firmly against the respective rotor sealing surface, thereby increasing the contact area between the two adjacent sealing surfaces. This, in turn, increases friction and thus heat generation.

[0016] The sealing friction pads are made of, or can be made of, a thermoplastic. As is well known, friction generates heat, and heat softens thermoplastics. This means that with increasing pressure in the tire inflation system and the accompanying pressure increase in the rotary union, the friction on the sealing surfaces increases, and with the resulting greater heat generation, the sealing friction pad softens, thus increasing the contact area (sealing surface), generating even more friction and inevitably even more heat; it is therefore a (negative) cycle without end.

[0017] Therefore, this rotary union is not suitable for use in fluid systems where high or very high pressures prevail, such as in fluid systems for machine tools.

[0018] Furthermore, the work spindles in machine tools, and especially in machining centers for chip-forming manufacturing, which are increasingly complex, operate at speeds well above 10,000 rpm. In high-speed machining, spindle speeds of up to 50,000 rpm are sometimes achieved.

[0019] Excessive heat generation is very harmful in these systems; even the slightest increase in heat in components or assemblies of these machines must be avoided.

[0020] WO 2014 / 161704 A1 also discloses a mechanical seal arrangement whose sliding rings have sliding surfaces of different hardness to prevent abrasion and reduce wear.

[0021] DE 10 2005 036 338 A1 discloses a mechanical seal, in particular a cassette mechanical seal. An annular rotor is sealed and rigidly connected to a rotatable shaft. Two sliding rings, between which the rotor is arranged, are also provided. Sliding surfaces are arranged on the rotor and the sliding rings so that the rings can rotate with a seal relative to each other. The rotor and the sliding rings are covered by an annular cassette arranged coaxially with the rings, the rotation of which relative to the rings is prevented by an anti-rotation device. The sliding rings, i.e., their sliding surfaces, are each pressed axially against the respective sealing surface of the rotor by means of a spring-like energy storage device to ensure adequate sealing. The sliding surfaces of the sliding rings are essentially under preload, which increases friction and thus heat generation.

[0022] The disadvantage of this arrangement is the high maintenance effort due to increased wear from friction; moreover, a so-called dry running of the arrangement is not possible. Object of the invention

[0023] Starting from this state of the art, the invention is based on the objective of creating a sealing unit, with at least one radial passage, for conveying a fluid from a stationary machine part to a rotating machine part of a machine tool or an accessory for machine tools, such as driven tools, which is applicable in a working process known in technical circles as "wet running" and also in a working process known in technical circles as "dry running", and in which friction, in particular on its sealing surfaces, as well as heat generation are reduced and which requires less maintenance and lower manufacturing costs. Description of the invention

[0024] According to the invention, this problem is solved by a sealing unit having the features of claim 1. Dependent claims 2 to 9 disclose embodiments of the sealing unit according to the invention. The problem is also solved by a method for sealing a radial passage of such a sealing unit having the features of method claim 10.

[0025] The new sealing unit, with at least one radial passage for conveying a fluid from a stationary machine part to a rotating machine part, is based on a known rotary distributor equipped with a stator, at least one rotor, and at least two sliding rings. The stator, rotor, and sliding rings are arranged coaxially around a system axis. The stator is designed for connection to the stationary machine part and is shaped accordingly on its outer surface, and accommodates the rotor on its inner surface. The rotor is designed for connection to or on the rotating machine part and is shaped accordingly on its inner surface. The rotor also has two rotor sealing surfaces spaced apart from each other. The sliding rings are arranged inside the stator and are in functional operative contact with the rotor.Each sliding ring has at least one sealing surface located on its front side. Each sealing surface and rotor sealing surface form a sealing pair and work together to seal the radial passage.

[0026] According to one aspect of the invention, in this new sealing unit the normals to the sealing surfaces of the rotor are axially directed towards each other and the normals to the sealing surfaces of the sliding rings point axially away from each other.

[0027] According to the inventive method for sealing a radial passage of such a sealing unit, which is used on a machine for conveying a fluid from a stationary machine part to a rotating machine part, and which has a stator, at least one rotor and at least two sliding rings, wherein the rotor and the sliding rings have functionally cooperating sealing surfaces, a new working step / functional step consists in the fact that, with and during the pressurization of the fluid, the sliding rings are moved axially from their initial position by the pressurized fluid alone, in the direction of the respective opposite rotor sealing surface, so that the sealing surface of the sliding rings is pressed against the respective sealing surface of the rotor in such a way thatthat the pressed sealing surfaces can slide against each other with significantly reduced friction compared to prior art solutions, and a seal is simultaneously achieved.

[0028] A further, new step in the process involves moving the previously pressed sealing surfaces of the rotor and the respective sliding ring away from each other after the fluid pressure is released – a state known as depressurization. The sliding rings then return to their axial starting position. This new method for sealing a radial passage of such a sealing unit makes it possible to use the same sealing unit in both "wet" and "dry" operation. By significantly reducing or completely eliminating the contact force on the sealing surfaces of the rotor and the sealing surface of the respective sliding ring – i.e., on each sealing pair – there is no disruptive friction during dry operation.On the one hand, wear on the sealing unit is reduced, and on the other hand, which is very important for machine tools, machine tool assemblies and machine tool accessories, heat development (temperature increase) on functionally important components / assemblies, such as a tool spindle, is counteracted.

[0029] According to another aspect of the invention, the rotor, with its two outer flanges, forms a clamp that holds the two sliding rings and the stator axially within predetermined axial tolerances. In the radial direction, the stator and the sliding rings are positioned relative to the rotor by the coaxial design.

[0030] In an advantageous embodiment of the new sealing unit, an outer annular groove is formed on the outer circumference of the rotor, in which the sliding rings are arranged, with the side surfaces of this annular groove serving as the rotor sealing surfaces. This design is both cost-effective and very robust with regard to wear and maintenance requirements.

[0031] In the type of sealing units known in the prior art, in which the sliding rings are usually pre-tensioned with one or more springs, tilting moments, i.e. torques, are generated on the sliding rings, resulting in increased friction on surfaces moving against each other.

[0032] This disadvantage is not present in the sealing unit according to the invention.

[0033] According to a supplementary, advantageous embodiment, the outer annular groove in the outer circumference of the rotor and an area of ​​the inner surface of the stator, in particular its guide surfaces for the sliding rings, together form a receiving cage for the sliding rings.

[0034] According to a further advantageous embodiment of the new sealing unit, the rear sides of the sliding rings are arranged facing each other and spaced apart from each other, forming an annular gap, which facilitates the introduction of force into the sliding rings for pressing their sealing surfaces against the rotor sealing surfaces.

[0035] It is also advantageous that this annular gap is part of the radial passage for the conveyance of the fluid.

[0036] A further advantage is achieved when several radially oriented recesses are arranged in these back surfaces, the radial recesses preferably having the form of a half-through hole and penetrating the respective back surface. Furthermore, in the case of an even multiple of the number of recesses, these multiple recesses are advantageously arranged diametrically opposite each other, i.e., two recesses are diametrically opposed to each other. In the case of an odd multiple of the number of recesses, these multiple recesses are preferably arranged with a uniform distance between adjacent recesses.

[0037] If, in an unforeseen situation that may arise under certain circumstances, the back sides of the sliding rings should come into contact with each other, the radial passage for the conveyance of the fluid will not be interrupted, i.e., not blocked.

[0038] To avoid such a situation from the outset, one embodiment provides that a spacer pin engages in at least one of the radial recesses arranged in the back sides of the sliding rings. This also secures the sliding rings against rotation in the stator. Preferably, a spacer pin engages simultaneously in one recess of each of the two sliding rings.

[0039] According to a further aspect of the invention, an advantageous embodiment consists in the fact that the sliding rings are each arranged with an elastic positioning ring on an inner guide surface of the stator. The sliding rings are, so to speak, mounted / held on a pendulum support. The desired axial movement of the sliding rings is achieved using simple technical means.

[0040] This elastic positioning ring also has a second function. When the fluid being conveyed is pressurized, this elastic positioning ring simultaneously acts as a seal. The contact area between the elastic positioning ring and the respective inner guide surface of the stator, as well as the contact area between the elastic positioning ring and the sliding ring, is increased in magnitude, so that each of these contact surfaces becomes a sealing surface. The pressurized fluid causes the necessary deformation of the elastic positioning ring.

[0041] According to one variant of this embodiment, the elastic positioning ring is arranged in a circumferential groove present in the outer surface of the sliding ring.

[0042] According to another variant of this embodiment, the circumferential groove for receiving the positioning ring is arranged in the relevant section of the inner guide surface of the stator.

[0043] If the elastic positioning ring is located in this circumferential groove, the fluid, when pressurized, flows through a minimal circumferential gap between the sliding ring and the inner guide surface into this circumferential groove and simultaneously presses the elastic positioning ring against one of the groove flanks of this circumferential groove, thus creating a further locking surface.

[0044] In addition, this elastic positioning ring also has a third function: each positioning ring is elastically deformed during the axial movement of the sliding rings in the direction of the respective rotor sealing surface and becomes a power storage device.

[0045] When the fluid is depressurized, this energy storage device, i.e., the elastically deformed positioning ring, supports, on the one hand, during a transition period, i.e., at the beginning and during the pressure drop, the further sealing, i.e., a temporal extension of the sealing in the relevant areas of the sealing unit, and also the movement of the sliding rings back to their initial position, which will be discussed in more detail later.

[0046] In a further advantageous embodiment of the new sealing unit, it is provided that an end-face indentation is arranged in the front of each of the sliding rings, which forms a recessed annular surface, so that the respective sliding ring sealing surface is a protruding annular surface, wherein the sliding ring sealing surface is arranged in the outer area of ​​the front.

[0047] According to an advantageous embodiment of the new sealing unit, the recessed annular surface on the front of the sliding rings, in conjunction with a section of the opposite rotor sealing surface and a section of an outer circumferential surface of the rotor facing the sliding rings, forms a circumferential backpressure chamber. The compressed fluid that accumulates in this backpressure chamber during pressurization assists the sliding rings in returning to their initial position after the pressurization is switched off.The cross-section of the annular supply gap, through which the fluid is forced into the counter-pressure chamber during pressurization, is chosen such that when the pressurization is switched off, the pressure reduction in the counter-pressure chamber occurs so slowly that, as mentioned above, the compressed fluid present here first pushes and then supports the movement of the sliding rings back to their starting position.

[0048] Due to the design of the sealing unit according to the invention, the pressure drop in the counter-pressure chamber and in the circumferential grooves, in which the elastic positioning rings are arranged, is slower than in the annular gap and the annular channel located between the sliding rings when transitioning from the pressurized to the unpressurized state. An advantage is that the fluid flows inwards from the rotor sealing surfaces or sliding ring sealing surfaces.

[0049] Another advantage is that the sealing effect of the deformed positioning ring diminishes with a time delay, meaning that the sealing surfaces created in the pressurized state do not abruptly, but gradually become contact surfaces again.

[0050] The leakage that occurs in known technical solutions after a pressure drop is also avoided with the sealing unit according to the invention.

[0051] Further advantages of the invention include simpler and more cost-effective repair of the sealing components in case of wear. Generally, only the sliding rings and / or ring discs, which are relatively simpler compared to conventional sliding rings and counter rings, need to be replaced. The stator, its ring body, and the rotor with its two rotor rings do not need to be replaced.

[0052] Furthermore, the so-called repetition rate of this sealing unit has been improved, since the left and right sliding rings are identical components. The left and right ring discs are also identical components.

[0053] A coating on these sealing parts further reduces friction and extends their service life.

[0054] Furthermore, the application range of this new sealing unit is possible and permissible for various pressure ranges and speed ranges; that is, the "from-to range" is larger compared to state-of-the-art solutions, since in particular no energy storage devices in the form of compression and / or tension springs, whose application area is limited, are used.

[0055] The invention is explained in more detail below with reference to schematic representations shown in the drawings and to an exemplary embodiment. Brief description of the drawings

[0056] They show: Fig. 1 shows an embodiment of the sealing unit according to the invention in a perspective view; Fig. 2 shows the sealing unit according to Fig. 1 in a frontal view; Fig. 3 the sealing unit according to Fig. 1 in a longitudinal section according to section AA; Fig. 4 which is in the Fig. 3 Marked detail B of the sealing unit, in the unpressurized state; Fig. 5, which is shown in the Fig. 3 Marked detail B of the sealing unit, in the pressurized state; Fig. 6 also shows the one in the Fig. 3 Marked detail B of the sealing unit, in the pressurized state, with regard to further details of the invention; Fig. 6adie in the Fig. 6 Marked detail A of the sealing unit, in the pressurized state, regarding further details of the invention; Fig. 7, which is shown in the Figures 4 , 5 and 6Detail B shown, without depiction of the sliding rings, with regard to further details of the invention; Fig. 8 the rotor of the sealing unit according to the invention. Figures 1 to 7 Regarding further details; Fig. 9 the sliding rings of the sealing unit according to the invention. Figures 1 to 6a in individual part representation; Fig. 10 the stator of the sealing unit according to the invention. Figures 1 to 7 in individual part representation regarding further details. Detailed description of the drawings and example of implementation

[0057] It should first be noted that terms such as "left," "right," "top," "bottom," "front," and "back" refer only to the representation in the figures and may differ from the actual arrangement in practice. Furthermore, it should be noted that the figures are not purely technical drawings, which is why hatching and break lines are sometimes missing. In addition, the relative dimensions may differ from reality. Reference symbols not mentioned in the description can be found in the reference symbol list. The reference symbols have the same meaning in all figures.

[0058] The Fig. 1Figure 1 shows a possible embodiment of the sealing unit 1 according to the invention in a perspective view. The rotor 6, consisting of the two components 7 and 8, is arranged in a stator 5, here a ring body. The sliding rings, which are arranged between the rotor 6 and the stator 5, are not yet visible here. A frontal view of the new sealing unit 1 shows the Fig. 2 , in which the sectioning for section AA is also defined with regard to the representation in Fig. 3 is marked.

[0059] First, the representations according to the Figures 8 to 10 The individual parts of the sealing unit 1 are described in their essential details.

[0060] As the depictions in Fig. 8As shown, in this embodiment the rotor 6 essentially consists of 4 parts, namely the first, the left rotor ring 7 and the second, the right rotor ring 8, as well as a ring disk 13 and 14 each, which have the same shape but are arranged in a mirror image in the installed position.

[0061] The left rotor ring 7 consists of a connecting bushing 11 with a flange 9 projecting radially on the left side. At least two through threaded bores 75 are arranged diametrically in the flange 9. An annular groove, which is not assigned a reference numeral, is provided in the outer surface 29 of the connecting bushing 11 near the flange 9. Extending inwards from its right end face 19, an inner bushing surface 25 is provided, which terminates at a shouldered annular surface 27. This shouldered annular surface 27 is followed by an inner cylindrical surface 21, which has a smaller diameter. This inner cylindrical surface 21, together with an inner cylindrical surface 22 of the right rotor ring 8, forms the rotor inner surface 23, see Figure 1. Figure 3 .

[0062] Immediately in front of the shoulder ring surface 27, an inner ring groove 26 is incorporated into the inner surface 25 of the bushing, the diameter of which is only slightly larger than the diameter of the inner surface 25 of the bushing.

[0063] In the connecting bushing 11, several radially directed and diametrically arranged passages 30 are also provided, which break through the outer surface 29 starting from the inner annular groove 26.

[0064] In the left-hand ring disc 13, base bores 77 extending inwards from the end face on the left side are arranged. At least two base bores 77 are provided; their number and position (pitch) are matched to the arrangement of the through threaded bores 75 of the flange 9. The inner diameter of this ring disc 13 is matched to the diameter of the outer surface 29. This left-hand ring disc 13 is slid onto the outer surface 29 and brought up to the contact surface 17 of the flange 9. Before sliding it on, a sealing ring (usually an O-ring) is inserted into the annular groove provided in the outer surface 29. A threaded stud 76 is screwed into each through threaded bore 75 until its head is in the respective base bore 77. This secures the left-hand ring disc 13 against rotation; see the Figures 3 , 4 , 5 , 6 and 7 .

[0065] The right rotor ring 8 consists of a connecting pin 12 with a flange 10 projecting radially to the right. The connecting pin 12 is a hollow pin. At least two through threaded bores 74 are arranged diametrically in the flange 10. The outer surface of the connecting pin 12 is stepped. Starting from its left end face 24, there is first an outer surface 28 with a smaller diameter, which terminates at a stop surface 20. This stop surface 20 is followed by a receiving shoulder 32 extending to the flange 10. The left end face of the flange 10 is a bearing surface 18 for the right ring disk 14.

[0066] This right-hand ring disc 14 is designed almost as a mirror image of the left-hand ring disc 13. Several basic bores 77 are also provided on its end face, which faces the flange 10.

[0067] The right ring disc 14 is pushed onto the receiving shoulder 32 until it rests against the contact surface 18; before this, a sealing ring (usually an O-ring) is inserted into the ring groove provided there (without reference numeral).

[0068] A threaded stud 76 is screwed into each through threaded bore 74 until its head is in the respective base bore 77. This secures the right-hand ring washer 14 against rotation; see the Figures 3 , 4 , 5 , 6 and 7 .

[0069] The right free end face of the left ring disc 13 is the left rotor sealing surface 15 and the left free end face of the right ring disc 14 is the right rotor sealing surface 16 of the rotor 6.

[0070] The assembly of the rotor parts will be discussed further later.

[0071] The sliding rings 40L and 40R are in the Figure 9Shown in two views. Both sliding rings have the same shape; they are arranged as mirror images when installed. The left illustration in the Figure 9 Figure 1 shows a frontal view of the sliding ring 40L. The illustration in the middle shows this sliding ring 40L in a longitudinal section according to section BB; the section line is shown in the left illustration. The right illustration in this Figure 9 shows the right sliding ring 40R, i.e. a mirror image of the left sliding ring 40L.

[0072] The outer end faces of the two sliding rings 40L and 40R are the sliding ring sealing surfaces 43 and 44 respectively, which functionally interact with the rotor sealing surfaces, i.e., with the left rotor sealing surface 15 and the right rotor sealing surface 16 respectively.

[0073] The facing end faces of the two sliding rings 40L and 40R, i.e., the rear faces 41 and 42 of each sliding ring respectively, form a force application surface. Each sliding ring 40L, 40R has a continuous cylindrical inner surface 45 and a cylindrical outer surface 73, which are arranged concentrically to each other, as well as a circumferential groove 49 extending inwards from the outer surface 73, which has a groove base 70 and groove flanks 71 and 72 spaced apart from each other, which define the groove width.

[0074] In the force application surfaces 41, 42, i.e., the rear faces of the sliding rings 40L and 40R, several radially oriented and diametrically arranged recesses 47 are incorporated, which have a substantially semicircular cross-section and divide this end face, more precisely the remaining annular surface, into several annular segments, see the left illustration in Figure 9 .

[0075] At the transition, i.e. at the edge formed by the back side 41 or 42 and the inner surface 45, a sloping surface 48 is arranged, which is also a channel wall, which will be discussed in more detail later.

[0076] In the end face of each sliding ring 40L and 40R, which has the sliding ring sealing surface 43 or 44 respectively, an inwardly directed indentation 46, a recessed annular surface, is machined. This recessed annular surface 46 extends from the inner surface 45 and reaches towards the outer diameter of the sliding ring so far that the sliding ring sealing surface 43 or 44 protrudes as a narrow annular surface.

[0077] Stator 5 is solo in the Fig. 10 shown. The left illustration shows a longitudinal section through the stator 5 and the right illustration in the Figure 10a cross-section according to section CC. The stator 5 consists of a ring body 50, with a horizontal body axis 51 and a vertical plane of symmetry 52, in which the section line of section CC is also laid. A groove 59 on the outer ring is arranged centrally in its outer surface 80 with respect to its two outer end faces 61 and 62.

[0078] Its inner cylindrical surface is stepped multiple times. Starting from the outer end face 61 or 62, a receiving section 53 or 54 is arranged, followed by a guide surface 55 or 56. The diameter of the guide surfaces 55 and 56 is smaller than the diameter of the receiving sections 53 and 54. An inner annular groove 58 is arranged between the two guide surfaces 55 and 56. Several radially oriented through-holes 57 are arranged in this inner annular groove 58, which penetrate the cylindrical surface 80. The multiple through-holes 57 are arranged in diametrically opposed pairs. One of the through-holes 57 has an internal thread 60.

[0079] The sealing unit 1 is in the Fig. 3 in a longitudinal section, according to section AA from Fig. 2The unit is shown fully assembled and in a depressurized state. The individual parts, in particular the sliding rings 40L and 40R, are in the position for so-called dry running. The dashed lines symbolically indicate the rotating machine part, a hollow shaft 3, on which the rotor 6 is positioned and locked. The hollow shaft 3 has an inner channel 4. Fig. 3 For the sake of clarity, the passages extending from the outer surface of the hollow shaft 3 and leading to the inner channel 4, through which the fluid is guided from the inner annular groove 26 to the inner channel 4, are not shown. The hollow shaft 3 and the sealing unit 1 are arranged coaxially with the system axis 2.

[0080] The first rotor ring 7 and the second rotor ring 8 are nested together to form the rotor 6. For further information, see the additional section below. Figures 8 to 10, the outer surface 28 of the connecting pin 12 of the right rotor ring 8 is inserted into the inner surface 25 of the connecting bushing 11 of the left rotor ring 7 and the end face 19 of the connecting bushing 11 is brought up to the stop surface 20 of the connecting pin 12.

[0081] Previously, the two ring discs 13 and 14 were positioned on the contact surface 17 and 18 of the flanges 9 and 10 respectively, and then the left sliding ring 40L was pushed onto the outer surface 29 of the left rotor ring 7.

[0082] This assembly is then inserted from the left into the ring body 50 of the stator 5 and positioned so that the flange 9, together with the ring disc 13, is located in the left receiving section 53 and the left sliding ring 40 L is located in the left guide surface 55. Before inserting this assembly, an elastic positioning ring 64 was also inserted into the circumferential groove 49 of the sliding ring 40 L, which rests in its intended position against the left guide surface 55.

[0083] After positioning this assembly in the ring body 50, the right sliding ring 40 R together with the elastic positioning ring 64 inserted in its circumferential groove 49 is pushed onto the outer surface 29 of the left rotor ring 7 from the right, i.e. starting from the right outer end face 62, with the elastic positioning ring 64 resting against the right guide surface 56.

[0084] Then a spacer pin 63, a threaded pin with a pin, is screwed into the through bore 57 of the ring body 50 which has the internal thread 60 until it engages in one of the radial recesses 47 of both sliding rings 40 L and 40 R and thus keeps the rear sides 41 and 42 of these sliding rings at a distance.

[0085] Finally, as mentioned above, the right rotor ring 8 is inserted into the connecting socket 11 of the left rotor ring 7 with the outer surface 28 of its connecting pin 12.

[0086] The stator 5, the sliding rings 40L and 40R, and the rotor 6 are positioned such that the through-bores 57, the inner ring groove 58, the radial recesses 47, the inclined surfaces 48, and the passages 30, together with the inner ring groove 26, are symmetrical to the vertical plane of symmetry 52 of the stator 5 and thus together form the radial passage for the conveyance of the fluid F. Figure 3The direction of flow of the fluid F is marked by arrows, to which the reference symbol F is assigned.

[0087] In the Figure 4 is the one in Figure 3 Marked detail B is shown on a larger scale so that further details are more clearly visible.

[0088] The rotor sealing surfaces 15 and 16 provided on the ring discs 13 and 14 respectively are positioned such that the normals on these rotor sealing surfaces 15 and 16 are directed axially towards each other, while the mechanical sealing surfaces 43 and 44 provided on the sliding rings 40L and 40R respectively are positioned such that the normals on these mechanical sealing surfaces 43 and 44 point axially away from each other.

[0089] The connection between the left rotor ring 7 and the right rotor ring 8 is sealed with a standard sealing ring (without reference numeral); likewise, the ring disc 13 and the ring disc 14 are sealed against the outer surface 29 and the receiving shoulder 32 respectively with a standard sealing ring (without reference numeral).

[0090] The rear faces 41 and 42 of the sliding rings 40L and 40R face each other, and between them is a gap, the annular gap 35. An annular channel 34 is formed with the inclined surfaces 48 of both sliding rings 40L and 40R and the outer surface 29 of the rotor 6. This annular channel 34 is connected to the inner annular groove 26 of the rotor 6 via the multiple passages 30.

[0091] Since the elastic positioning ring 64 only rests on the respective guide surface 55 or 56 of the ring body 50 of the stator 5 and the respective groove bottom 70 of the circumferential grooves 49 of the sliding rings 40L, 40R during the so-called pressureless state, the dry running, i.e., it is not pressed against it, each sliding ring 40L, 40R is held between its guide surfaces 55, 56, so to speak, by a pendulum support.

[0092] The elastic positioning ring 64 ensures that the sliding ring 40L or 40R is in its axial target position.

[0093] Furthermore, a continuous gap is provided between the inner surface 45 of each sliding ring 40L, 40R and the relevant section of the outer surface 29 of the rotor 6.

[0094] In the Figure 5 is also the one in the Figure 3Marked detail B is shown on a larger scale. However, this illustration shows the pressurized state. The fluid F provided in the stationary machine part 79 is introduced by pressure through the through-bores 57 into the sealing unit 1 for conveyance to the rotating machine part 3 (see Figure 3 The fluid F then enters the recesses 47 and the annular gap 35; see also the Figures 6 and 6a The force inherent in the pressurized fluid F is then transmitted via the rear surface 41 or 42, the force application surface, to each sliding ring 40L, 40R, whereby the sliding ring sealing surface 43, 44 arranged on the opposite end face of each sliding ring 40L, 40R is pressed against the respective rotor sealing surface 15, 16 in such a way that a hydraulic seal is created between each pair of the sliding sealing surfaces 15, 43; 16, 44, so that no fluid F can flow out there.

[0095] Since there is a continuous gap, a supply gap 37, between the inner surface 45 of each sliding ring 40L, 40R and the corresponding section of the outer surface 29 of the rotor 6, the pressurized fluid F reaches the counter-pressure chamber 36, which also circulates. This counter-pressure chamber 36 is formed by the recessed annular surface 46 on the sliding ring 40L, 40R, the free annular surface section of the corresponding rotor sealing surface, and the corresponding section of the outer surface 29 of the rotor 6. The pressurized fluid F also exerts a force on each sliding ring 40L, 40R here, but now in the opposite direction, so that the pressure area is identical to the sliding sealing surface, and thus the sealing surfaces 15, 16 on the rotor 6 and the sealing surfaces 43, 44 on the sliding rings 40L, 40R are protected from unnecessary friction and therefore from excessive wear.

[0096] Since a clearance fit is provided between the outer surface 73 of the sliding rings 40L, 40R and the respective guide surfaces 55, 56, the pressurized fluid F also enters the circumferential groove 49 of each sliding ring 40L, 40R via this clearance fit and the minimum gap 38. There, the pressurized fluid F acts as a force on the free outer surface of the elastic positioning ring 64 and presses it against the groove flank 71 facing the sliding surface, see Fig. 9, this circumferential groove 49. At the same time, the body of the elastic positioning ring 64 is also pressed in both radial directions, so that the contact area of ​​the elastic positioning ring 64 on the groove bottom 70 and on the respective guide surface 55, 56 is increased in magnitude, so that the contact area on the guide surface 55, 56 becomes an upper sealing surface 65 and the contact area on the groove bottom 70 becomes a lower sealing surface 66; in addition, the contact surface of the elastic positioning ring 64 on the groove flank 71 becomes a lateral sealing surface 67. Thus, the radial passage for the conveyance of a fluid F in the sealing unit 1 is now sealed on all sides.

[0097] The respective flow direction of the fluid F as well as the forces transmitted by the pressurized fluid F are in the Figures 5 , 6 and 6a marked with corresponding arrows.

[0098] The axial load movement R1 acting on the sealing surfaces of the sliding rings 40L, 40R is in the Figures 6 and 6a The axial unloading movement R2 of the sliding rings 40L, 40R acting with respect to the sealing surfaces is shown in the Fig. 4 marked.

[0099] As already stated at the beginning of the description, the rotor 6, with its outer surface 29 and the two flanges 9 and 10 arranged laterally at a distance from each other, against which the ring discs 13 and 14 are placed, which have the respective rotor sealing surface, forms an outer annular groove 31 in which the sliding rings 40L, 40R are positioned; this is shown in the Figure 7 The illustration shows this in detail. This outer annular groove 31, together with the guide surfaces 55 and 56 of the ring body 50 of the stator 5, forms the receiving cages 33 also mentioned at the beginning of the description, in which the sliding rings 40L, 40R are held and guided.

[0100] At the same time, the rotor 6 with its flanges 9 and 10 forms a holding clamp for the sliding rings 40L, 40R and the stator 5.

[0101] It should also be noted that the rotor 6 is attached to the hollow shaft 3 using known and conventional methods; this can be done by press fit, adhesive bonding, or with known locking elements 78, the latter fastening method being described in the Figure 6 hinted at.

[0102] In another possible embodiment, the elasticity factor of the elastic positioning ring is selected such that each sliding ring, within a range of 0.001 to 1.0 millimeters, preferably within a range of 0.005 to 0.05 millimeters, can be moved axially, i.e., returned to its original position, after the pressure is switched off, by the force stored in the positioning ring due to its temporary deformation. According to a further possible embodiment, the depth of the indentation 46 is between 0.001 and 2.0 millimeters, preferably between 0.001 and 0.2 mm. Reference symbol list

[0103] 1 Sealing unit 2 System shaft 3 Hollow shaft (rotating machine part) 4 Inner channel 5 Stator (ring body) 6 Rotor (hollow cylindrical) 7 First rotor ring (left rotor ring) 8 Second rotor ring (right rotor ring) 9 Flange 10 Flange 11 Connecting bushing 12 Connecting pin (hollow pin) 13 Left ring disc 14 Right ring disc 15 Left rotor sealing surface (sliding surface) 16 Right rotor sealing surface (sliding surface) 17 Contact surface (at position 9) 18 Contact surface (at position 10) 19 End face (of position 11) 20 Stop surface (at position 10) 21 Inner cylinder surface (of position 7) 22 Inner cylinder surface (of position 8) 23 Rotor inner surface (of position 6) 24 End face (of position 8) 12) 25 Inner bushing surface (in item 11) 26 Inner ring groove (in item 6) 27 Shoulder ring surface (between items 25 and 21) 28 Outer surface (of item 12) 29 Outer surface (of item 11) 30 Passages (between items 26 and 29) 31 Outer ring groove (between items 13 and 14 and 11 of item 6) 32 Receiving shoulder (for item14) 33 Receiving cage 34 Annular channel 35 Annular gap 36 Back pressure chamber (circumferential) 37 Feed gap 38 Minimum gap (clearance fit) 40 Left sliding ring 40 Right sliding ring 41 Rear of left sliding ring (force introduction surfaces) 42 Rear of right sliding ring (force introduction surfaces) 43 Sealing surface of left sliding ring 44 Sealing surface of right sliding ring 45 Inner surface 46 Frontal recess (recessed annular surface) 47 Radial recesses 48 Slanted surface (channel wall) 49 Circumferential groove 50 Ring body (Pos. 5) 51 Horizontal body axis 52 Vertical plane of symmetry 53 Left receiving section (in Pos. 50) 54 Right receiving section (in Pos. 50) 55 Left guide surface (in Pos. 50) 56 Right guide surface (in pos. 50) 57 Through holes (in pos. 50, radial) 58 Inner ring groove 59 Outer ring groove (at pos. 50) 60 Internal thread 61 Left outer end face 62 Right outer end face 63 Spacer pin (threaded pin with pin) 64 Elastic positioning ring (also sealing ring) 65 Upper locking surface (at pos.64) 66lower locking surface (at item 64) 67side locking surface (at item 64) 68-69- free reference numerals - 70groove bottom 71groove flank (sliding surface side) 72groove flank (pressure surface side) 73shell surface (of items 40L and 40R) 74through threaded hole 75through threaded hole 76threaded pins 77basic holes 78locking part 79stationary machine part 80shell surface (of item 50) . FFluid R1axial loading movement (from position 40L and 40R) R2axial unloading movement (from position 40L and 40R)

Claims

1. Sealing unit (1) for onward conduction of a fluid (F) from a stationary machine part (79) to a rotating machine part (3) on a machine tool or an accessory for a machine tools such as, for example, driven tools, which unit (1) for that purpose is equipped with a stator (5), at least one rotor (6) and at least two slide rings (40L,40R) as well as with at least one radial passage (57, 47, 34, 30, 26) for onward conduction of the fluid (F), wherein - the stator (5), the rotor (6) and the slide rings (40L, 40R) are arranged coaxially with a system axis (2), - the stator (5) is provided for connection with the stationary machine part (79) and is correspondingly shaped in its outer region and receives the rotor (6) in its inner region, - the rotor (6) is provided for a connection with or on the rotating machine part (3) and is correspondingly shaped in its inner region, - each slide ring (40L, 40R) has at least one slide ring sealing surface (43, 44), wherein - the rotor (6) has two rotor sealing surfaces (15, 16) arranged at a mutual spacing, - the slide rings (40L, 40R) are arranged within the stator (5) and are in functional operative connection with the rotor (6), - a respective slide ring sealing surface (43, 44) and rotor sealing surface (15, 16) form a sealing pair (15, 43; 16, 44) and functionally co-operate, - the normals to the sealing surfaces (15, 16) of the rotor (6) are directed axially towards one another and the normals to the sealing surfaces (43, 44) of the slide rings (40L, 40R) face axially away from one another.

2. Sealing unit (1) according to claim 1, characterised in that an outer annular groove (31) in which the slide rings (40L, 40R) are arranged is formed in the outer circumference of the rotor (6), wherein the side surfaces of this annular groove (31) are the rotor sealing surfaces (15, 16).

3. Sealing unit (1) according to claim 1 or 2, characterised in that the rear sides (41, 42) of the slide rings (40L, 40R) face one another and are arranged at a mutual spacing with formation of an annular gap (35).

4. Sealing unit (1) according to claim 2 or 3, characterised in that the outer annular groove (31) in the outer circumference of the rotor (6) and a region (55, 56) of the inner surface of the stator (5) together form a receiving cage (33) for the slide rings (40L, 40R).

5. Sealing unit (1) according to claim 3 or 4, characterised in that the annular gap (35) is a component of the radial passage for the onward conduction of the fluid (F).

6. Sealing unit (1) according to claim 1, 2, 3, 4 or 5, characterised in that the slide rings (40L, 40R) are each arranged to be axially movable by a resilient positioning ring (64) at an inner guide surface (55 or 56) of the stator (5).

7. Sealing unit (1) according to claim 3, 4, 5 or 6, characterised in that a plurality of radially oriented recesses (47) is arranged in the rear sides (41, 42) of the slide rings (40L, 40R), wherein the radial recesses (47) preferably have the form of half a passage bore and pass through the respective rear side.

8. Sealing unit (1) according to claim 1, 2, 3, 4, 5, 6 or 7, characterised in that a respective end-face turned recess (46) is arranged in the front side of the slide rings (40L, 40R) and forms a recessed annular surface so that the respective slide ring sealing surface (43 or 44) is a projecting annular surface, wherein the slide ring sealing surface (43, 44) is arranged in the outer region of the front side.

9. Sealing unit (1) according to claim 8, characterised in that the recessed annular surface (46) in the front side of the slide rings (40L, 40R) in conjunction with a section of the rotor sealing surface (15 or 16) opposite thereto and with a section of an outer surface (29), which faces the slide rings (40L, 40R), of the rotor (6) forms an encircling counter-pressure space (36).

10. Method of sealing the radial passage of a sealing unit (1) according to any one of claims 1 to 9, characterised in that the fluid (F) loads the slide rings (40L, 40R) in terms of force simultaneously with and during pressure loading on the fluid (F) to be conducted onward so that the respective sealing surface (43, 44) of the slide rings (40L, 40R) is pressed against the relevant sealing surface (15, 16) of the rotor (5) in such a way that the sealing surfaces (15, 43; 16, 44) pressed against one another can slide against one another with substantially reduced friction and at the same time a sealing is effected, and that after removal of the pressure loading on the fluid (F) the sealing surfaces (15, 43; 16, 44) previously pressed against one another are relatively moved away from one another so that in a so-called dry run there is no disruptive friction between the sealing surfaces (15, 43; 16, 44).