SHAFT ASSEMBLY, GEARBOX WITH A SHAFT ASSEMBLY AND EXTRUDER WITH GEARBOX WITH A SHAFT ASSEMBLY, WITH A SHAFT ROTATABLY BASED RELATIVELY TO A FLANGE PART

Description

[0001] The invention relates to a shaft arrangement, a gear with a shaft arrangement and an extruder with a gear with a shaft arrangement, with a shaft rotatably mounted relative to a flange part.

[0002] It is common knowledge that shaft seals are used to seal transmission shafts.

[0003] From the DE 38 21 971 A1 A stuffing box is known for sealing a shaft with a large runout error.

[0004] From the EP 1 893 898 A1 A radial sealing device for use in a radial pump is known.

[0005] From the KR2011 0069955 A The closest state of the art is a shaft arrangement.

[0006] From the WO 2018 / 132413 A1 A passive fault-tolerant shaft sealing arrangement is known.

[0007] From the EP 1 267 107 A1 is a rod primary seal with the features of the preamble of claim 1 known.

[0008] The invention is therefore based on the object of developing a seal in a shaft arrangement for high pressure differences.

[0009] According to the invention, the object is achieved in the shaft arrangement according to the features specified in claim 1 and in the gear or in the extruder according to the features specified in claim 12.

[0010] Important features of the invention in the shaft arrangement with a shaft rotatably mounted relative to a flange part are that a sleeve is placed on the shaft and connected in a rotationally fixed manner, in particular is connected in a materially and force-locking manner, wherein the flange part has a first annular groove and a second and / or third annular groove coaxially aligned with the first annular groove, wherein one or more sealing arrangements are arranged in the second and / or third annular groove, wherein the respective sealing arrangements each have a base ring which is radially surrounded by a respective outer ring, wherein the base ring touches the sleeve and the outer ring touches the wall of the second annular groove, wherein a guide ring for centering the sleeve is arranged in the first annular groove,

[0011] in particular wherein the guide ring touches both the sleeve and the wall of the annular groove.

[0012] The advantage here is that the guide ring aligns the shaft coaxially with the base ring, thus ensuring the base ring's running conditions are as constant as possible. This allows even high pressure differences to be sealed. The base ring lies flat against the sleeve and is pressed against the outer ring by the outer ring, as the outer ring is elastically tensioned, specifically pre-tensioned, and thus the base ring is shrunk onto the sleeve by the outer ring.

[0013] In an advantageous embodiment, the guide ring is supported on the wall of the first annular groove, and there is a sliding contact between the guide ring and the sleeve toward the sleeve. The advantage here is that, while the guide ring is also rotatable relative to the flange part and / or the sleeve, the guide ring essentially functions as a centering element or as an additional centering bearing for the sleeve, so that the base rings operate efficiently with the most constant running conditions possible.

[0014] In an advantageous embodiment, the outer ring is designed as an O-ring. This allows for a simple, cost-effective design.

[0015] In an advantageous embodiment, the base ring contacts the sleeve over its entire surface, in particular the contact surface of the sleeve with the base ring is a cylindrical section and / or the base ring is made of a polyethylene, in particular an ultra-high molecular weight polyethylene. This is advantageous because it enables simple centering of the sleeve coaxially with the ring grooves and / or base rings.

[0016] In an advantageous embodiment, the guide ring contacts the sleeve flatly, in particular, the contact surface between the sleeve and the guide ring is a section of the cylinder surface. This is advantageous because efficient centering of the sleeve is achieved.

[0017] In an advantageous embodiment, the guide ring is made of a harder material than the base ring. This is advantageous because the guide ring coaxially centers the sleeve, thus keeping the running conditions for the base rings constant.

[0018] In an advantageous design, the contact surface between the sleeve and the guide ring is wider in the axial direction than the contact surface between the sleeve and the base ring. This is advantageous because the forces required for centering can be efficiently dissipated.

[0019] In an advantageous embodiment, the first annular groove is radially less extended than the second annular groove. This is advantageous because the guide ring is wider axially than radially. This allows for efficient centering by the guide ring.

[0020] In an advantageous embodiment, the first annular groove is arranged axially between the second and third annular grooves. This is advantageous in that the distance between the first annular groove and the other two annular grooves is small, thus ensuring that the centering effect achieved by the guide ring is effective for the two base rings. The axial distance between the first annular groove and the second and / or third annular groove is smaller than the inner radius of the guide ring, in particular, smaller than half the diameter of the annular opening of the guide ring.

[0021] According to the invention, a V-ring is accommodated on the sleeve on the side of the second annular groove facing away from the first annular groove, the sealing lip of which contact the flange part, wherein the V-ring is spaced axially from the annular grooves. This has the advantage that material conveyed by the extruder screw, which is connected to the shaft in a rotationally fixed manner via the extruder screw coupling, does not penetrate, or only insignificantly, into the sealing area between the flange part and the sleeve. The V-ring is arranged in such a way that the material is kept out of the sealing area in the event of a pressure drop towards the sealing area. If, in another operating state, the area of ​​the material is subject to negative pressure or vacuum, the V-ring will open, but the seal provided by the two sealing arrangements arranged in the second and third annular grooves is sufficient to prevent lubricating oil from being sucked out of the gear unit into the area of ​​the material.

[0022] According to the invention, the flange part is connected to a one-piece or multi-piece housing part in which at least one bearing is accommodated which rotatably supports the shaft, wherein the smallest distance of the annular grooves from the bearing, measured in the axial direction, is greater than half the inner diameter of the bearing, in particular half the inner diameter of the inner ring of the bearing resting on the shaft. The advantage here is that although the shaft is mounted, the sleeve is pushed onto and connected to a protruding end region of the shaft, so that the sleeve is aligned coaxially to the base rings by means of the centering by the guide ring and the concentricity of the sleeve has deviations of less than one hundredth, even though the sleeve has an outer diameter of more than 100 mm.

[0023] In an advantageous embodiment, the base ring, in its relaxed state, has a surface section on its inner side that resembles the surface of a circular cylinder, in particular, whose axial width is greater than half the largest diameter of the ring's cross-section. This is advantageous in that it can be placed flat against the sleeve, i.e., without point contact, thus enabling a high degree of protection and / or high sealing.

[0024] According to the invention, the outer ring, the V-ring and / or the guide ring are made of FKM, in particular fluorocarbon rubber, in particular wherein the material of the V-ring has a lower hardness than the material of the outer ring and than the material of the guide ring, in particular wherein the material of the base ring has a greater hardness than the material of the base ring, than the material of the guide ring and / or than the material of the V-ring, and / or that the sleeve is made of hardened steel. The advantage here is that cost-effective materials can be used. The sleeve can be made of hardened steel that is finely machined, and good sealing conditions can therefore be achieved. Since the guide ring is harder than the base ring, centering can be carried out by the guide ring and the base ring only has to be made of a material that, when paired with the material of the sleeve, results in a very low coefficient of friction.According to the invention, the outer ring is made of an elastic material so that the base ring is shrunk on and pre-tensioned and thus pressed against the sleeve.

[0025] According to the invention, the shaft and sleeve are designed as a single part, i.e., one-piece, particularly one-piece. This has the advantage of reducing the number of parts.

[0026] Important features of the gearbox with the aforementioned shaft arrangement or of the extruder with a gearbox with the aforementioned shaft arrangement are that an extruder screw is connected to the shaft via the extruder screw coupling in a rotationally fixed manner, particularly by means of spline engagement. An advantage here is that the extruder, which includes the extruder screws, can be operated alternately with vacuum and overpressure. In both operating modes, the area of ​​the material conveyed by the extruder screw is sealed from the interior of the gearbox.

[0027] Further advantages arise from the subclaims.

[0028] The invention will now be explained in more detail using schematic illustrations: In the Figure 1 is a drive comprising a gear 1 driven by an electric motor, of an extruder having extruder screw couplings 2 shown in an oblique view. In the Figure 2 a cross-section through an output area of ​​the extruder having one of the extruder screw couplings 2 is shown.

[0029] As shown in the figures, the respective extruder screw coupling 2 is positively connected to a shaft 13, in particular by means of a spline 11.

[0030] The extruder screw coupling 2 is axially delimited by a cover plate 12, which is delimited by a screw head of a screw that is screwed into an axially directed threaded bore of the shaft 13.

[0031] A sleeve 8 made of hardened steel is slid onto an axially protruding sleeve section of the extruder screw coupling 2. This advantageously reduces friction. The sleeve is pressed onto the shaft 13 and adhesively bonded.

[0032] The shaft 13 is connected to the extruder screw coupling 2 in a rotationally fixed manner. The shaft 13 is rotatably mounted via bearings 14, which are preferably designed without tension. The bearing 14 is accommodated in a bearing flange 16, in particular a housing part.

[0033] The bearing flange 16 is detachably connected to a housing part 10, which is detachably connected to a flange part 7.

[0034] Shaft sealing rings 15 are accommodated in the bearing flange 16, wherein the sealing lips of the shaft sealing rings 15 run on a second sleeve made of hardened steel which is connected to the shaft 13 and which in turn is pressed onto the shaft 13 and adhesively bonded.

[0035] The bearings 14 are arranged on the side facing away from the seal 15 in the axial direction and are thus arranged in the interior of the gearbox 1 which is at least partially filled with lubricating oil, wherein toothed parts which are in engagement with one another are also arranged in the interior of the gearbox 1.

[0036] The housing parts are tightly connected to each other to form the housing of the gearbox 1.

[0037] To protect the interior of the gearbox, the shaft sealing rings 15 act as an oil seal, but a very high pressure and, depending on the operating condition, even a vacuum is provided on the extruder screw side.

[0038] Therefore, a V-ring is mounted on the sleeve 8, the sealing lip of which presses against a finely machined annular surface of the flange part 7. The flange part has two circumferential annular grooves.

[0039] A sealing arrangement is accommodated in each of the two annular grooves. The sealing arrangement comprises a base ring 3, which is radially surrounded by an outer ring 4. The outer ring 4 is preferably made of a first plastic and preferably shaped as an O-ring. The outer ring 4 is preferably integrally connected to the base ring 3 and elastically deformed such that it is pressed against the wall of the annular groove. In this way, the outer ring 4 seals between the base ring 3 and the wall of the annular groove.

[0040] The outer ring 4 thus fulfills the sealing function of an O-ring. Furthermore, it is also designed to introduce a shrinkage force, i.e., a force field that exerts a clamping force on the base ring 3 at all circumferential positions, in particular the same, radially inwardly directed force.

[0041] The base ring 3 rests against the sleeve 8, with the contact area in the axial direction not being a point contact, but a linear contact. For this purpose, the base ring 3 has a cylindrical surface section as an inner surface in the contact area, which contacts the sleeve 8. The base ring 3 thus slides relative to the sleeve 8 when the shaft 13 is set in rotation relative to the gearbox housing. To reduce friction losses, a suitable second material is selected as the material of the base ring 3. The second material is preferably a plastic or rubber.

[0042] Although a brass ring coated with Teflon, in particular PTFE, in particular polytetrafluoroethylene, could also be used as the base ring 3, a fiber composite material is preferably used which also comprises a material which, in combination with the sleeve 8, i.e. hardened steel, results in a very low coefficient of friction.

[0043] The two annular grooves are spaced apart from each other in the axial direction. Each of the annular grooves contains a seal comprising the described base ring 3 and, integrally bonded to it, an outer ring 4 designed as an O-ring radially surrounding the respective base ring.

[0044] Axially between the two annular grooves, a further annular groove, preferably radially less extended than the two annular grooves, is formed in the flange part 7, in which a guide ring 6 is arranged.

[0045] The guide ring 6 is made of a second material, in particular plastic, wherein the second material is harder than the first material.

[0046] Since the guide ring 6 lies flat against the sleeve 8, centering of the sleeve 8 together with the shaft 13 connected to the sleeve 8 is achieved.

[0047] This is because the shaft 13 is mounted in the gearbox via the bearings 14 of the gearbox, so that the shaft end protruding from the gearbox with the sleeve 8 arranged on it is slide-mounted by means of the guide ring 6.

[0048] The guide ring 6 thus ensures that the sleeve 8 is centered relative to the receiving bore of the flange part 7, so that the base rings 3 do not have to absorb any radial transverse impacts or transverse movements, but are exposed to running conditions that are as constant as possible.

[0049] The V-ring 5 keeps dirt and material conveyed by the extruder screws away from the sealing area between sleeve 8 and flange part 7.

[0050] The radial expansion of the annular groove accommodating the guide ring 6 is less than the radial expansion of the respective annular groove accommodating the respective sealing arrangement.

[0051] In further embodiments of the invention, the housing, comprising flange part 7, housing part 10, and bearing flange 16, is constructed from a smaller number of parts by constructing flange part 7 and housing part 10 as a single piece, and optionally also constructing bearing flange 16 together with flange part 7 and housing part 10 from a single piece. This allows for simpler manufacturing because fewer parts need to be handled.

[0052] The shaft arrangement according to the invention can be used not only for gears but also for other devices in which an effective seal against an area with material under high or low pressure is to be realized and a bearing of the shaft is not preloaded and / or is further away in the axial direction, i.e. in the direction of the axis of rotation of the shaft 13, than half the diameter of the shaft 13, in particular in the area of ​​the bearing receptacle of the bearing of the shaft 13 arranged closest to the seal. List of reference symbols

[0053] 1 Gear 2 Extruder screw coupling 3 Base ring 4 Outer ring 5 V-ring 6 Guide ring 7 Flange part, in particular housing part 8 Sleeve 9 Seal 10 Housing part 11 Toothing, in particular spline 12 Cover plate 13 Shaft 14 Bearing, in particular unstressed bearing 15 Shaft seal 16 Bearing flange, in particular housing part

Claims

1. A shaft arrangement with a shaft (13) rotatably mounted in relation to a flange part (7), wherein a sleeve (8) is placed on the shaft (13) and is connected non-rotatably, in particular is connected by a material-formed bond and in a force-fit, or wherein the shaft (13) together with a sleeve are embodied as a single part, i.e. in one part, in particular in one piece, wherein the flange part (7) has a first annular groove and a second and / or third annular groove oriented coaxially with the first annular groove, wherein a or in each case one sealing arrangement is arranged in the second and / or third annular groove, wherein the respective sealing arrangement in each case has a base ring (3) which is surrounded radially by a respective outer ring (4), wherein the base ring (3) contacts the sleeve (8) and the outer ring (4) contacts the wall of the second annular groove, wherein a guide ring (6) for centring the sleeve (8) is arranged in the first annular groove, wherein the guide ring (6) contacts both the sleeve (8) and the wall of the annular groove, wherein a V-ring (5) is accommodated on the sleeve (8) on that side of the second annular groove which is remote from the first annular groove, wherein the V-ring (5) is spaced apart from the annular grooves in the axial direction, wherein the outer ring (4) is made of an elastic material, so that the base ring (3) is pretensioned by being shrunk on and thus is pressed against the sleeve (8), characterised in that the sealing lip of the V-ring (5) contacts the flange part (7), with the outer ring (4), the V-ring (5) and / or the guide ring (6) being manufactured from fluororubber, in particular therefore fluorocarbon rubber, with the flange part (7) being connected to a housing part (10) made in one part or in multiple parts, in which housing part is accommodated at least one bearing (14) which rotatably mounts the shaft (13), with the shortest distance of the annular grooves from the bearing (14), measured in the axial direction, being greater than half the internal diameter of the bearing, in particular than half the internal diameter of the inner ring of the bearing which lies against the shaft (13).

2. A shaft arrangement according to claim 1, characterised in that the guide ring (6) is supported on the wall of the first annular groove, and towards the sleeve (8) there is sliding contact between the guide ring (6) and sleeve (8).

3. A shaft arrangement according to one of the preceding claims, characterised in that the outer ring (4) is embodied as an O-ring.

4. A shaft arrangement according to one of the preceding claims, characterised in that the base ring (3) contacts the sleeve (8) with its face, in particular therefore the face of contact of the sleeve (8) with the base ring (3) is a lateral cylinder surface portion and / or the base ring (3) is manufactured from a polyethylene, in particular from a polyethylene with an ultra-high molecular weight, or the base ring (3) is a brass ring coated with PTFE, in particular Teflon.

5. A shaft arrangement according to one of the preceding claims, characterised in that the guide ring (6) contacts the sleeve (8) with its face, in particular therefore the face of contact of the sleeve (8) with the guide ring (6) is a lateral cylinder surface portion.

6. A shaft arrangement according to one of the preceding claims, characterised in that the guide ring (6) is made from a harder material than the base ring (3).

7. A shaft arrangement according to one of the preceding claims, characterised in that the face of contact between the sleeve (8) and guide ring (6) in the axial direction is broader than the face of contact between the sleeve (8) and base ring (3).

8. A shaft arrangement according to one of the preceding claims, characterised in that the first annular groove is extended radially less than the second annular groove.

9. A shaft arrangement according to one of the preceding claims, characterised in that the first annular groove is arranged between the second and the third annular groove in the axial direction.

10. A shaft arrangement according to one of the preceding claims, characterised in that the base ring (3) in the relaxed state has on its inside a surface portion which is equal to a lateral regular-cylinder surface, in particular the axial width of which is greater than half the largest diameter of the ring cross-section.

11. A shaft arrangement according to one of the preceding claims, characterised in that the material of the V-ring (5) has a lesser hardness than the material of the outer ring (4) and than the material of the guide ring (6), and / or in that the sleeve (8) is made of hardened steel.

12. A gear unit (1) with a shaft arrangement according to one of the preceding claims or an extruder with a gear unit (1) with a shaft arrangement according to one of the preceding claims, wherein an extruder screw coupling (2) is connected non-rotatably, in particular by means of splines, to the shaft (13).