Torsionally flexible gear and gear assembly for a screw compressor

Abstract

The invention relates to a torsionally flexible gear, a gear assembly of a screw compressor or screw blower comprising such a gear, and a method for damping vibrations, preferably torsional vibrations, of a gear assembly. The torsionally flexible gear comprises a hub part (10) for connection with a shaft (2) of a gear assembly (100) of a screw compressor (300) or screw blower, a rim part (20) with teeth (7), preferably helical teeth, wherein the hub part (10) and the rim part (20) are rotatable relative to each other in the circumferential direction of the gear (1), and at least one elastic damping element (30) for damping vibrations in the circumferential direction of the gear (1).Between an outer area (12) of the hub part (10) and an inner area (22) of the gear ring part (20), at least one recess (40) is formed for receiving the at least one damping element (30), into which the at least one damping element (30) is received for transmitting a torque between the hub part (10) and the gear ring part (20). At least one support disc (50, 60) extends radially between the hub part (10) and the gear ring part (20) and is designed for axial and radial support of the gear ring part (20) on the hub part (10).

Description

[0001] The invention relates to a torsionally elastic gear, a gear arrangement of a screw compressor or screw blower comprising such a gear and a method for damping vibrations, preferably torsional vibrations, of a gear arrangement of a screw compressor or screw blower.

[0002] Screw compressors are used to compress gases, particularly for generating compressed air or for compressing other process gases, such as helium. Screw blowers differ from screw compressors in that they operate at a lower pressure ratio. Screw compressors or screw blowers are frequently available as oil-injected or water-injected models, but also as dry compressors or blowers. In dry compressors, the bearings are lubricated, but the rotors (compressor rotors) are not. In oil-lubricated screw compressors, the oil supplied to the compressor block lubricates, cools, and seals the rotors against each other and against the compressor block housing. The rotor shaft bearings are typically oil-lubricated.The compressor block, in which the screw rotors are rotatably mounted, can be driven by a drive motor via a direct coupling, a belt drive, or a gear drive. Lubrication of the gear drive is necessary for reliable operation. The bearings of the drive motor's drive shaft are typically grease-lubricated.

[0003] For a compact design of the screw compressor or screw blower, the compressor block can be directly connected to the motor block via a common housing, without a separate gearbox housing being provided for the gearbox located between the motor block and the compressor block. In practice, the motor block is often manufactured separately and then connected to the compressor block. The motor housing and the compressor housing are connected to each other via flange connections.

[0004] In conventional screw compressors, vibrations in the drive train are often dampened by a torsionally flexible coupling located between the compressor block (screw block), which contains the compressor rotors (screw rotors), and the drive motor. Some screw compressors also incorporate a gearbox between the compressor block and the drive motor for speed adjustment, ensuring optimal utilization of the motor's power at any adjustable pressure level. To save space, components, and costs, it is desirable to eliminate the need for an additional conventional torsionally flexible coupling and a gearbox shaft, particularly in stationary screw compressors.

[0005] From EP 4 112 937 A1, a gear arrangement for connecting a drive motor and an oil-lubricated compressor block of a screw compressor is known. This gear arrangement comprises a gear unit with a drive gear connected to a drive shaft of the drive motor and an output gear connected to an output shaft that drives the compressor block and thus constitutes the drive shaft of the screw compressor. The drive gear and the output gear mesh with each other. A shaft passage opening for the drive shaft is formed in a drive housing section and is sealed by a mechanical seal. The mechanical seal prevents oil from escaping from the gear unit into the motor compartment and also prevents the gas to be compressed in the compressor block from flowing into the motor compartment. In the gear arrangement, the drive shaft (motor shaft) is supported at both ends.On the side where the drive gear is mounted is the gearbox-side (A-side) drive bearing (motor shaft bearing). On the opposite side is the drive-side (B-side) drive bearing (motor shaft bearing). The drive shaft (motor shaft) runs through the motor compartment and protrudes at one end through a shaft passage opening formed in a drive housing section into the gearbox compartment. The gearbox-side drive bearing (motor shaft bearing) is located between the mechanical seal and the drive gear of the transmission stage. The drive gear is mounted on the drive shaft in the gearbox compartment, i.e., in an axial section of the drive shaft outside the two bearing points (so-called cantilever bearing).

[0006] The gearbox arrangement described in EP 4 112 937 A1 ensures simple lubrication of the gearbox-side drive bearing by the oil present in the gearbox compartment. The lubricating oil supplied to the oil-lubricated compressor block in the gearbox compartment is used to lubricate the gearbox stage and the gearbox-side drive bearing. The drive bearing on the side facing the drive gear comes into contact with the oil present in the gearbox compartment and is thus lubricated without any additional design measures. Oil lubrication of the gearbox-side drive bearing is achieved without an additional lubrication device. No separate bearing lubrication is necessary for the gearbox-side drive bearing, in particular no grease lubrication. The described cantilevered mounting enables, among other things, a compact design of the unit consisting of the compressor block and drive motor (block-motor unit).

[0007] From WO 2019 / 043469 A1, a screw compressor with drive gears and synchronization gears is known, wherein at least one of these gears is designed with spokes and the spaces between the spokes are filled with a damping material. In this solution, the torque is not transmitted via the damping material, but via the spokes.

[0008] WO 2021 / 156778 A1 discloses a spoked gear for the gearbox of a screw compressor, wherein, to improve damping properties, the spaces between the spokes are filled with a block of rigid, incompressible material, and a viscoelastic material is located between the gear and the block. In this solution as well, the torque is not transmitted via the damping material, but via the spokes.

[0009] A device for vibration damping in a gearbox with damping elements for a damped transmission of a rotary motion is known from WO 2011 / 047807 A1. The damping elements are cylindrical stop elements with a rubber coating, which are screwed to the drive shaft.

[0010] From AT 501915 A4 a device for torsionally flexible torque transmission between a shaft and a gear with coupling parts is known, wherein the coupling parts are supported exclusively in the circumferential direction by elastomeric damping elements and the gear ring is mounted in a radially rigid manner relative to the shaft via the hub.

[0011] DE 10 2009 058 378 A1 discloses a gear with an inner ring and an outer ring, the outer ring having external teeth, wherein the outer ring is radially supported relative to the inner ring by an elastic element. The elastic element, in the form of an elastic O-ring, sits in an annular groove on an inner circumferential surface of an annular web of the outer ring. In an unloaded state, the external teeth and a mating tooth are radially elastically preloaded or clamped relative to each other. For lubrication purposes, a (radial) connecting channel is provided, which connects the central bore of the inner ring with the outer circumferential surface of the inner ring.

[0012] AT 520740 B1 describes a gear in which elastomeric elements made of rubber-elastic materials are arranged between a radially inner and a radially outer ring element. These elements are prestressed by compression in the axial direction and are at least approximately cuboid in shape. It is proposed that the radially inner and radially outer ring elements could be made of two different metallic materials. It is also conceivable that the radially inner ring element and / or the radially outer ring element could be made of a polymeric plastic. This gear can only transmit limited torques and is therefore limited in terms of the drive power that can be transmitted. Due to the torques to be transmitted, this gear is unsuitable for use in the screw compressors described above.The radial and axial bearing arrangement between the radially inner and radially outer ring elements is unfavorable and insufficient for the loads occurring when driving screw compressors.

[0013] EP 3 809 017 A1 shows a resin gear, which has a metal ring bushing and a resin ring section surrounding it, forming a tooth profile. The metal ring bushing and the resin ring section are rotatable relative to each other in the direction of rotation of the gear. A multitude of cavities penetrate an outer circumferential surface of the metal ring bushing and an inner circumferential surface of the resin ring section, in which elastic elements are arranged for damping purposes. The elastic elements are made of rubber. After an adhesive is applied to the inside of the cavities, rubber is injected into them, filling them. The elastic elements take shape within the cavities. This gear can only transmit limited torques and is therefore limited in terms of the drive power it can transmit. Due to the torques to be transmitted, it is unsuitable for use in the screw compressors described above.The direct radial bearing between the inner metal ring bushing and the outer resin ring section also leads to unfavorable contact conditions in the tooth mesh. Lubrication is not addressed.

[0014] DE 10 2008 013 865 A1 concerns a torsional vibration damper for an internal combustion engine and is based on so-called tube-in-tube shafts in vehicle construction, in which an elastic buffer or damping layer made of an elastomer is arranged in the gap between the outer diameter of an inner tube and the inner diameter of an outer tube. Similarly constructed torsional vibration dampers for damping torsional vibrations on the side of the crankshaft facing away from the output shaft have various disadvantages, such as irreversible chemical aging, relaxation, and temperature-dependent changes in spring characteristics. As a solution, it is proposed to insert a shaft with a non-circular outer circumference into a flywheel with a non-circular inner circumference and to arrange an elastic wire cushion in the space between them. These wire cushions are subjected to shear stress to transmit a torque.A relatively steep torsional characteristic curve when the wire cushion is fully compressed is described as advantageous for various applications.

[0015] In addition to the aforementioned limitations of conventional gears regarding the transmissible forces and torques, there is the problem of the limited durability of the damping elements used when in contact with lubricant, especially lubricating oil. This problem is exacerbated in oil-injected screw compressors, as the oil used there ages rapidly due to oxidation from constant contact with air, consequently subjecting the components in contact with it to higher stress.

[0016] Based on this prior art, the present invention aims to improve the smooth running of an (oil-injected) screw compressor or screw blower, particularly one with a cantilevered gear on a drive shaft, and to reduce the acoustic emissions during operation of the (oil-injected) screw compressor or screw blower, using the simplest possible design means. This solution is intended, in particular, to ensure the damping of vibrations, especially torsional vibrations, that occur in the drive train of the screw compressor or screw blower.Furthermore, a gearbox arrangement for an (oil-injected) screw compressor or screw blower is to be created that does not require a conventional torsionally flexible coupling, enables the screw compressor or screw blower to be as compact a design as possible, and has the longest possible service life, especially with regard to the operating conditions of a screw compressor or screw blower.

[0017] This problem is solved by the subject matter of the claims. In particular, the problem is solved by a torsionally elastic gear according to the invention, a gear arrangement according to the invention for a screw compressor or a screw blower, the use according to the invention of such a gear for vibration damping in a gear arrangement of a screw compressor or screw blower, and by a method according to the invention for damping vibrations, preferably torsional vibrations, of a gear arrangement.

[0018] In particular, the problem is solved by a torsionally flexible gear, preferably for a gear arrangement of a screw compressor or screw blower, comprising - a hub part, preferably made of metal, for connection to a shaft of a gear assembly of a screw compressor or screw blower, - a gear ring part, preferably made of metal, with teeth, preferably helical teeth, for meshing with teeth of a mating gear of the transmission arrangement, wherein the hub part and the gear ring part are rotatable relative to each other in the circumferential direction of the gear, - at least one elastic damping element for damping vibrations in the circumferential direction of the gear, wherein at least one recess for receiving the at least one damping element is formed between an outer area of ​​the hub part and an inner area of ​​the gear ring part, in which the at least one damping element for transmitting a torque between the hub part and the gear ring part is received, and - at least one support disc extending radially between the hub part and the gear ring part, designed for axial and radial support of the gear ring part on the hub part, wherein the at least one support disc has at least one axial support sliding surface for axial support of the gear ring part on the hub part and at least one radial support sliding surface for radial support of the gear ring part on the hub part.

[0019] A torsionally flexible gear like this can improve the smooth running of a screw compressor or screw blower and reduce acoustic emissions during operation. The at least one elastic damping element can dampen vibrations in the circumferential direction of the gear (torsional vibrations), particularly undesirable vibrations that can occur in resonance frequency ranges when a screw compressor or screw blower is driven by a (variable-speed) drive motor (electric motor) via a gearbox. The torsionally flexible gear is particularly suitable for gearboxes or screw compressors with a cantilevered gear on the drive shaft to dampen torsional vibrations. The aspects and advantages of the invention described below with reference to a screw compressor also apply to a screw blower.

[0020] By providing at least one support disc for the axial and radial support of the gear ring section on the hub section, the torsionally flexible gear can be described as rigid in the axial and radial directions, but elastic (torsionally flexible) in the circumferential direction. The gear ring section is not supported axially and radially directly on the hub section, but (indirectly) via the at least one support disc, preferably (on both sides) via two support discs. This allows the relative radial and axial positioning of the hub section and the gear ring section to remain unchanged during operation of the gear, so that the design-provided gap dimensions of the axial and / or radial gaps between the hub section, the gear ring section, and / or the at least one support disc do not (essentially) change during operation.Due to the axial support of the gear ring section, the gear is suitable for absorbing axial forces resulting from helical gearing. Helical gearing is typically preferred due to its lower noise generation, particularly in screw compressors and screw blowers. The gear is specifically designed to transmit the torque entirely (i.e., only) via the at least one damping element (i.e., not via the at least one support disc). The at least one damping element is specifically arranged such that it absorbs (essentially) no radial and / or axial forces.

[0021] The axial direction refers to the direction of the axis of the shaft to which the gear is connected. This shaft can be, in particular, a drive shaft of a motor (motor shaft) for driving a screw compressor, or a drive shaft of the screw compressor (screw rotor shaft) or screw blower. A radial direction extends perpendicular to the axial direction. The circumferential direction refers to the direction of rotation of the gear when it is connected to a rotating shaft. An axial surface is oriented (with its surface normal) (essentially) in the axial direction. A radial surface is oriented (with its surface normal) (essentially) in the radial direction. The axial and / or radial support surfaces may be (slightly) convex.

[0022] Preferably, a plurality of (identical) recesses for receiving (one) elastic damping element each are arranged (uniformly) distributed around the circumference of the gear. Similarly, a plurality of (identical) elastic damping elements are preferably arranged (uniformly) distributed around the circumference of the gear. In preferred embodiments, 6 to 16, preferably 8 to 14, more preferably 10 to 12, and particularly preferably 12 damping elements are arranged (uniformly) distributed around the circumference. The damping elements are, in particular, elastically deformable. When subjected to vibration, preferably in specific frequency ranges, the damping elements exhibit specific damping characteristics, which are preferably matched to the resonance frequency ranges occurring in the drive train of a screw compressor.A damping element is preferably cylindrical and preferably has a longitudinal axis that extends axially when the damping element is installed. The cross-section (in the axial plane) of the damping element is preferably circular, rectangular, or trapezoidal. The plurality of damping elements are preferably designed as separate components that are (loosely) received in the respective recess, but preferably are not (fixed) connected to the gear ring part and / or hub part. The choice of material for the damping elements is not limited in that the damping elements do not need to be vulcanized to the hub part or the gear ring part, as is sometimes customary in the prior art.Rather, the material of at least one damping element can be specifically selected for use in the gearbox of an oil-lubricated screw compressor to ensure high resistance (durability) of the damping element in the lubricating oil. In particular, with a suitable material selection, the resistance of the damping elements in the gearbox to elevated temperatures (e.g., up to 100°C) and the lubricating oils used for compressor lubrication can be improved. This results in a gearbox and gear that requires virtually no maintenance. The fact that the damping elements do not need to be vulcanized to the hub or ring gear also offers the advantage of easy replacement during repairs. Furthermore, recycling the components of the torsionally flexible gear is simpler when the damping elements are not vulcanized.

[0023] The hub part is preferably (permanently and detachably) connectable to a shaft, in particular a shaft of a gear assembly, such as a drive shaft of a drive motor or a screw compressor. The hub part and the gear ring part can be made of the same or different (metallic) materials, in particular steel or a steel alloy. The hub part and the gear ring part are not connected to each other by spokes, but are designed as separate components.

[0024] The at least one support disc is preferably designed as an annular disc, wherein the outer diameter of the support disc is larger than the inner diameter of the gear ring part and the inner diameter of the support disc is smaller than the outer diameter of the hub part (but larger than the diameter of the shaft). In this respect, the support disc at least partially overlaps the gear ring part and the hub part laterally. The at least one support disc can be made of the same or different (metallic) materials as the gear ring part and the hub part, preferably steel or a steel alloy, and can have surface coatings and / or treated (ground, hardened) surfaces, at least in certain areas, which particularly improve sliding and wear properties.

[0025] In a preferred embodiment, a support disc extends radially between the hub part and the gear ring part on both axial sides (i.e., two support discs on both sides), with each support disc designed to provide axial and radial support for the gear ring part against the hub part. This allows the hub part and the gear ring part to be manufactured with simple symmetry. In (less preferred) alternative embodiments, a single support disc (i.e., one support disc on one side) can be provided for support on one axial side, with the other axial side either having the hub part designed such that the gear ring part is supported (directly) against the hub part, or – conversely – having the gear ring part designed such that the hub part is supported (directly) against the gear ring part.The hub part or the gear ring part on the side of the gear axially opposite the support disc can be designed such that it has an axial support sliding surface for supporting the gear ring part in the axial direction on the hub part and at least one radial support sliding surface for supporting the gear ring part in the radial direction on the hub part.

[0026] Due to the described properties, the torsionally flexible gear according to the invention is suitable for use in screw compressors, particularly oil-lubricated screw compressors, with regard to the forces and torques that occur as well as the prevailing operating conditions (temperature, lubricating oil). The gear can (at least partially) dampen vibrations (torsional vibrations) that can occur in resonance frequency ranges in the drive train of the screw compressor, especially between the motor and the screw block. This allows vibrations of compressor components (screw rotors) as well as vibrations of gearbox components (shafts, gears) and the corresponding noise emissions to be avoided or at least reduced.Undesirable vibrations occurring in resonance ranges in torsionally rigid gearboxes, and also in cantilevered gear bearings, can be effectively and – especially compared to the use of a conventional vibration damper – broadband damped by the torsionally flexible gear according to the invention. In particular, natural frequencies can be shifted to less excited frequency ranges to reduce disruptive effects on operation. This allows for better implementation of flexible speed adjustment of a screw compressor. The available motor power can be better (fully) utilized at different pressure and power configurations of the screw compressor. In a gearbox arrangement for an (oil-injected) screw compressor with a gear according to the invention, a conventionally used torsionally flexible coupling can be dispensed with.This allows for a more compact design of the screw compressor (block-engine unit), as the compressor and gearbox can be directly flanged to the engine. The torsionally flexible gear can be pre-assembled and simply mounted on either the drive shaft of the compressor block or the drive shaft of the engine (engine shaft), replacing a conventional gear. It can be replaced with conventional (non-torsionally flexible) gears.

[0027] In one embodiment of the torsionally flexible gear, the at least one support disc comprises a first support disc and a second support disc, which are arranged opposite each other in the axial direction on both sides of the gear ring section. Preferably, the first support disc extends radially between the hub section and the gear ring section on a first axial end face of the gear and is designed to provide axial and radial support for the gear ring section on the hub section. Preferably, the first support disc has a first axial support sliding surface for axially supporting the gear ring section on the hub section and a first radial support sliding surface for radially supporting the gear ring section on the hub section. Preferably, the second support disc extends radially between the hub section and the gear ring section on a second axial end face of the gear and is designed to provide axial and radial support for the gear ring section on the hub section.Preferably, the second support disc has a second axial support sliding surface for axially supporting the gear ring section on the hub section and a second radial support sliding surface for radially supporting the gear ring section on the hub section. Preferably, the first support disc and / or the second support disc rests against an axial end face of the hub section. The support discs ensure high stability of the assembly, both axially and radially. The predetermined distance of the gear to a mating gear of a gear stage and a defined meshing of the gears are thus maintained. In particular, the torsionally flexible gear is sufficiently stiff (axially and radially) to transmit (high) forces and torques, such as those that occur when driving a screw compressor.

[0028] In one embodiment of the torsionally flexible gear, the at least one support disc (or two support discs) is rigidly connected to the hub part, preferably by screws. In particular, the first support disc is (removably) rigidly connected to the hub part. In particular, the second support disc is (removably) rigidly connected to the hub part. Alternatively, at least one support disc is rigidly (removably) connected to the gear ring. The rigid connection can be (reversibly) detachable and, in particular, prevents relative displacement of the connected parts in the axial, radial, and circumferential directions. The rigid connection is preferably designed as a screw connection with several axial threaded bores distributed around the circumference in the hub part and corresponding axial through-holes through the support disc for screws (socket bolts).Preferably, the two support discs arranged on both sides of the hub part are clamped laterally against the hub part (with screws).

[0029] In one embodiment of the torsionally flexible gear, the gear ring section has a circumferential recess on at least one axial end face for receiving the at least one support disk. Preferably, an axial support sliding surface of the circumferential recess is designed to abut the axial support sliding surface of the support disk, and a radial support sliding surface of the circumferential recess is designed to abut the radial support sliding surface of the support disk. In particular, the gear ring section (through the circumferential recess) forms a step along the circumferential direction on at least one axial end face. The step of the gear ring section forms a circumferential edge that has a radial support sliding surface. The gear ring section is supported radially against the at least one support disk, especially at the radial support sliding surface.

[0030] In one embodiment of the torsionally flexible gear, the at least one support disc has a carbon coating, preferably a DLC coating, at least in the region of the axial support sliding surface and / or at least in the region of the radial support sliding surface. A DLC coating refers to a diamond-like carbon layer (DLC: Diamond-Like Carbon). Alternatively or additionally, a support sliding surface can be nitrided or case-hardened (before applying a DLC coating). Preferably, the first support disc and / or the second support disc has a carbon coating, preferably a DLC coating, in the region of the first axial support sliding surface and / or the second axial support sliding surface and / or the first radial support sliding surface and / or the second radial support sliding surface. A carbon coating serves to reduce the coefficient of friction at the contact surface and to protect against wear.

[0031] In one embodiment of the torsionally flexible gear, the at least one axial support sliding surface and / or the at least one radial support sliding surface can be supplied with lubricating oil via at least one lubricating oil channel from an outer surface of the gear, preferably from an axial support disc outer surface of the at least one support disc. Lubrication of the sliding (axial and / or radial) contact surfaces between the support disc(s) and the gear ring section (or alternatively, the hub section) reduces maintenance requirements and increases the service life of the gear. With a suitable arrangement of the gear within the gearbox of an oil-lubricated screw compressor, particularly with cantilevered mounting on a shaft projecting into the gearbox, the gear can come into contact with the lubricating oil present in the gearbox and be lubricated by the at least one lubricating oil channel without any additional design measures.

[0032] In one embodiment of the torsionally flexible gear, the at least one lubricating oil channel extends, preferably through the at least one support disc, to an axial gap between the support disc and the gear ring section. A plurality of lubricating oil channels can be arranged (uniformly) distributed around the circumference of the gear. Preferably, the lubricating oil channel extends at least partially in the axial direction, more preferably (essentially) in the axial direction or obliquely to the axial direction, through the at least one support disc. The lubricating oil channel is preferably designed as an (essentially) axial through-bore in a support disc. In the radial direction, the at least one lubricating oil channel is preferably arranged outside the hub section, more preferably in the radial region of the gear ring section, and particularly preferably (slightly) outside the at least one damping element.Such lubricating oil channels are easy to manufacture and, by design, simply ensure an adequate supply of lubricating oil.

[0033] In one embodiment of the torsionally flexible gear, the at least one support disk forms at least one collecting surface for lubricating oil on an axial outer surface of the support disk, at least along a portion of its circumference. The collecting surface is preferably formed by at least one axially projecting circumferential edge of the axial outer surface of the support disk. Preferably, an inlet opening of the at least one lubricating oil channel is formed at least partially on a radial inner surface of the collecting surface within an oil collection area of ​​the axial outer surface of the support disk. The inlet opening can be formed entirely on a radial inner surface of the collecting surface or extend (partially) into the area of ​​the axial outer surface of the support disk. The collecting surface preferably extends along a (radial) outer edge of the support disk. The collecting surface is preferably formed completely circumferentially.The collecting surface can be at least partially radially oriented or extend at least partially in the axial direction. The collecting surface can include surface sections oriented obliquely axially inwards (i.e., towards the center of the gear) that define a circumferential groove. In this respect, the collecting surface can form a nose-like shape in the radial cross-section of the axially projecting circumferential edge. The collecting surface (circumferential groove) can be formed by an undercut. The collecting surface can be formed by a central axial recess in the outer surface of the support disc and, in particular, by a step in the outer surface of the support disc in the radial direction, i.e., by an edge in the circumferential direction (possibly with an undercut).In particular, during operation (with the gear rotating), lubricating oil (oil droplets) is flung radially from the externally oiled gear and collected by the collection surface. This oil then accumulates in a collection area on the surface and flows axially through an inlet opening into the lubricating oil channels of the gear, lubricating and cooling the support sliding surfaces. During operation, the gear can heat up (for example, to 60°C to 85°C) and be cooled by the oil.

[0034] In one embodiment of the torsionally flexible gear, the at least one support disk on an axial inner surface and / or the gear ring section on at least one axial side has at least one circumferential groove for oil distribution in the circumferential direction, at least partially, in the area of ​​an axial gap between the support disk and the gear ring section. An outlet opening of the lubricating oil channel preferably opens into this groove. The at least one circumferential groove preferably extends radially into the area of ​​the at least one recess, particularly to supply the damping element accommodated therein with lubricating oil.

[0035] In a first embodiment of the torsionally flexible gear, the maximum outer diameter of the hub part is smaller than the minimum inner diameter of the gear ring part, and the at least one recess for receiving the at least one damping element is formed by radially opposing recesses in the hub part and the gear ring. Preferably, each of the at least one recess is adapted to receive a cylindrical damping element. Preferably, a radial gap is formed between at least one section of an outer circumferential surface of the hub part and at least one section of an inner circumferential surface of the gear ring part, preferably extending over the entire circumference. Damping elements received in such recesses are subjected primarily to compressive stress during relative rotation between the hub part and the gear ring part.

[0036] In a further embodiment of the torsionally flexible gear, particularly the first embodiment, the at least one damping element comprises at least one polymer, preferably at least one thermoplastic and / or at least one thermoplastic elastomer (TPE), which are preferably (radiation-)crosslinked. The damping element preferably has a Shore hardness D in the range of 50 to 65, particularly preferably from 55 to 63.

[0037] The at least one damping element can comprise at least one of the following materials: thermoplastic elastomer (TPE), preferably a thermoplastic polyamide elastomer (TPA), polyamide (PA), preferably PA12, polyethylene (PE), preferably cross-linked polyethylene (PE-X), PAEK, preferably polyetheretherketone (PEEK), polypropylene (PP). Alternatively or additionally, the at least one damping element can comprise at least one of the following materials: thermoplastic vulcanizate (TPV), polyurethane (PUR), thermoplastic polyurethane (TPU), and thermoplastic polyester elastomer (TPC). The damping element can also include at least one (vulcanized) elastomer, such as HNBR (hydrogenated nitrile-butadiene rubber), fluorocarbon rubber (FKM), perfluorocarbon rubber (FFKM), acrylonitrile butadiene rubber (NBR), polyacrylate rubber (ACM), acrylate ethylene rubber (AEM), epichlorohydrin rubber (ECO) and silicone rubber (e.g. VMQ).Relatively soft damping elements made of elastomers (Shore A hardness of up to 90), as known from the prior art, have good damping properties but exhibit only low strength. In a preferred embodiment, the elastic damping element consists of polyamide 12 (PA12). Damping elements made of these materials have good resistance to contact with compressor oils and are therefore particularly suitable for use in gearboxes for oil-injected screw compressors and screw blowers. These materials can contribute to a long service life of the torsionally flexible gear. Damping elements comprising a cross-linked, in particular radiation-cross-linked, thermoplastic can exhibit improved oil resistance. Radiation-cross-linked TPEs can also exhibit improved oil resistance.

[0038] Thermoplastic elastomers (TPEs) are plastics with properties similar to conventional elastomers, but they can be plastically deformed when heated, thus exhibiting thermoplastic behavior. They do not require curing or vulcanization during processing. Conventional elastomers are chemically loosely cross-linked three-dimensional network molecules whose cross-links cannot be broken without degrading the material. In contrast, thermoplastic elastomers have physical cross-linking points in certain areas that break down when heated without the macromolecules decomposing. Therefore, they are significantly easier to process than conventional elastomers. TPEs contain hard and soft polymer regions. During solidification below the melting temperature, the hard regions of the different chains bond together to form hard thermoplastic segments, while the soft regions form segments with elastomeric properties.As the proportion of soft segments increases, the elastomeric characteristics become more pronounced. Key advantages of thermoplastic elastomers include the low temperature dependence of their mechanical properties, the ability to adjust hardness and flexibility over a wide range, and good chemical resistance. Furthermore, TPEs do not contain plasticizers.

[0039] Crosslinking, particularly radiation crosslinking, allows for further improvement of the mechanical, thermal, chemical, and tribological properties of many thermoplastics and thermoplastic elastomers. During crosslinking, irreversible bonds are created between the molecules. This crosslinking process is similar to vulcanization in rubbers. Unlike chemical crosslinking, radiation crosslinking, as a physical process, offers the advantage of precise and reproducible adjustment of the properties.

[0040] In a further embodiment of the torsionally flexible gear, in particular the first embodiment, the at least one damping element comprises at least one thermoplastic polyamide polymer (TPA).

[0041] In a further embodiment, in particular the first embodiment, the damping element comprises first segments (hard segments), preferably polyamide segments, with a first (greater) hardness and second segments (soft segments), preferably polyether segments, with a second (lower) hardness, wherein the second hardness is lower than the first hardness.

[0042] In a further embodiment, particularly the first embodiment, several damping elements distributed around the circumference comprise (alternating) harder and softer materials. Preferably, damping elements comprising or consisting of polyamide segments (hard segments) are arranged (in the circumferential direction) alternately with damping elements comprising or consisting of polyether segments (soft segments).

[0043] In a further embodiment of the torsionally flexible gear, particularly the first embodiment, the at least one damping element has at least one cavity, wherein the at least one damping element is preferably designed as a hollow cylinder. Preferably, a (cylindrical) damping element has (exactly) one central (cylindrical) cavity. The cavity of the hollow cylinder may or may not be filled with another material. The hollow cylinder is preferably made of a polymer, preferably of a thermoplastic, and particularly preferably of polyamide or PEEK.

[0044] In a further embodiment of the torsionally flexible gear, particularly the first embodiment, the at least one damping element comprises a core comprising a first material with a first hardness and a casing comprising a second material with a second hardness, wherein the second hardness is preferably lower than the first hardness. The first material is preferably a metal or a (first) polymer (first thermoplastic elastomer). The second material is preferably a (second) polymer (second thermoplastic elastomer). The casing can be multilayered, with each of the casing layers being composed of different materials (polymers, preferably thermoplastic elastomers). The hardness of the casing (casing layers) can decrease from the inside out.

[0045] The core can consist of the first material and / or the cladding can consist of the second material, with a particularly abrupt material transition between the core and the cladding. The core can consist of metal or a (first) polymer and / or the cladding can consist of a (second) polymer. A continuous material transition can occur between the first material (first polymer) and the second material (second polymer). The first material (polymer) and the second material (polymer) are preferably thermoplastic elastomers (TPE).

[0046] The core (made of metal or polymer material) can be overmolded with polymer material. Preferably, the coating comprises a (softer) thermoelastic elastomer (second material) overmolded onto the (harder) core (first material, e.g., metal or PA12).

[0047] In a further embodiment of the torsionally flexible gear, particularly the first embodiment, the damping element comprises a core comprising a first (harder) polymer with a first (higher) hardness and a cladding comprising a second (softer) polymer with a second (lower) hardness, the second hardness preferably being lower than the first. A damping element can thus comprise a core made of a first (hard) material, e.g., PA12, wherein the core is encased, preferably overmolded, by a second (softer) material, e.g., a thermoplastic elastomer. A damping element can have one or more cavities (bores) to increase flexibility. Several damping elements distributed around the circumference can comprise (alternating) harder and softer materials.

[0048] The damping element can be manufactured by injection molding or extrusion. Preferably, the damping element has a (straight) cylindrical shape, but it can also be convex (bulbous).

[0049] The damping properties of the entire damping element can be adjusted over a wide frequency range by choosing the shape, e.g., as a hollow cylinder, and / or by choosing the material or materials.

[0050] In a second embodiment of the torsionally flexible gear, the hub part has radially outwardly projecting coupling projections and intervening coupling recesses on its outer surface, while the gear ring part has radially inwardly projecting coupling projections and intervening coupling recesses on its inner surface. Coupling projections of the hub part engage in coupling recesses of the gear ring part, and coupling projections of the gear ring part engage in coupling recesses of the hub part. A recess, preferably (essentially) cuboid in shape, is formed between a coupling projection of the hub part and a coupling projection of the gear ring part for receiving a damping element. In particular, the coupling projections of the hub part and the coupling projections of the gear ring part overlap along a circumferential direction at a specific radial position.Damping elements accommodated in such recessed spaces can be subjected to compression (in the circumferential direction) only when there is relative rotation between the hub part and the gear ring part. This enables force transmission in the circumferential direction via the damping elements without subjecting them to shear stress. Preferably, a radial gap is formed between at least one section of an outer circumferential surface of the hub part and at least one section of an inner circumferential surface of the gear ring part, which can extend over the entire circumference. The coupling projections of the hub part preferably have (essentially) radially extending (circumferentially oriented) side flanks.In particular, opposing side flanks of coupling projections of the hub part and coupling projections of the gear ring part are each (essentially) parallel to each other, wherein the recess space between them preferably has a rectangular cross-section (in the axial section plane), preferably (essentially) cuboidal. The lateral boundary surfaces of the recess space may (due to manufacturing constraints) extend radially outwards (and thus deviate from a precise cuboidal shape), whereby the recess space may have the shape of an annular segment, while the damping elements may be cuboidal. In this way, it can be ensured that a damping element received in the recess space is subjected to compression (i.e., only in the circumferential direction) when a torque is transmitted by the gear.

[0051] In a further embodiment of the torsionally flexible gear, particularly the second embodiment, the at least one damping element comprises a wire mesh. The wire mesh (its outer layer) preferably has a cuboid shape. Preferably, the damping element is pre-tensioned in a circumferential direction of the gear and / or oriented such that a main manufacturing pressing direction of the wire mesh runs along the circumferential direction of the gear. In the main manufacturing pressing direction, the damping element is preferably more easily compressible than perpendicular to it. The wire mesh is preferably produced (by pressing along a main manufacturing pressing direction) from a (spring-hard) steel wire (stainless steel wire).The damping element, designed as a wire mesh, is preferably pre-tensioned (circumferentially), preferably with an interference fit, and installed (using an assembly device) in the gear, particularly during gear assembly in a gap (part of a coupling recess) between a coupling projection of the hub part and a coupling projection of the ring gear part. The surfaces of the side flanks of coupling projections (contact surfaces with the wire mesh) can be at least partially (completely) nitrided, case-hardened, and / or DLC-coated.

[0052] In one embodiment of the torsionally flexible gear according to the second embodiment, during torque transmission in a specific main direction of rotation, only every second damping element (main damping elements) is loaded. When the direction of rotation changes, only the remaining damping elements (secondary damping elements) are loaded. Main damping elements and secondary damping elements can be designed differently, in particular exhibiting different damping properties, preferably different elasticity of the damping element (wire mesh), e.g., by different mesh density, wire thickness, and / or a different material (wire material).Depending on the direction of rotation, the torsionally flexible gear can exhibit different vibration damping properties, in particular the vibration damping properties (determined by main damping elements) in a main direction of rotation differ from the vibration damping properties (determined by secondary damping elements) of a secondary direction of rotation, preferably with regard to the damped frequency ranges.

[0053] In another embodiment of the torsionally flexible gear according to the second embodiment, damping elements are provided (only) on (exactly) one side (in the circumferential direction) of the coupling projections, wherein the damping elements are loaded (only) during torque transmission in a specific main direction of rotation. In this case, no secondary damping elements are present.

[0054] Furthermore, the aforementioned task is solved in particular by a gear arrangement for connecting a drive motor and a screw compressor or screw blower, comprising - at least one gear stage comprising a torsionally flexible gear according to the invention, - a drive shaft of a drive motor for driving the screw compressor or screw blower, and - a drive shaft of the screw compressor or screw blower, which is coupled to the drive shaft of the drive motor via at least one gear stage, wherein preferably the torsionally flexible gear is mounted on the drive shaft of the drive motor or on the drive shaft of the screw compressor or screw blower, wherein the drive shaft is preferably cantilevered.

[0055] The gear stage of the transmission arrangement preferably comprises a (multi-part) torsionally flexible gear according to the invention and a (one-piece) torsionally rigid gear, as known from the prior art, as the mating gear. Preferably, the torsionally flexible gear has helical teeth. The torsionally flexible gear can be the driving gear (pinion) or the driven gear (wheel). The hub part preferably sits on a tapered shaft section of the drive shaft and has a correspondingly tapered inner circumferential profile. The gear can be fixed to the drive shaft by a mounting washer, preferably axially clamped against the tapered shaft section, preferably by screwing the mounting washer to one shaft end. The mounting washer can be used as a puller for disassembly (i.e., for pressing the gear off the shaft).

[0056] Preferably, the torsionally flexible gear is mounted as a driving gear on a drive shaft of a drive motor (electric motor) and is in mesh with a torsionally rigid gear, which is mounted on a drive shaft of a screw compressor, preferably on a shaft section of a screw rotor. The torsionally flexible gear is preferably mounted on the drive shaft, viewed axially, in a shaft section of the drive shaft outside the two (axial and / or radial) bearing points of the drive shaft, particularly in a shaft end region of the drive shaft. In a preferred embodiment, the drive shaft projects from a motor compartment in which the drive motor is arranged, with its shaft end region (freely, i.e., without further support) into the gearbox compartment on which the torsionally flexible gear is mounted. In this respect, the torsionally flexible gear is preferably cantilevered.

[0057] The gearbox assembly can be lubricated by lubricating oil, which is (also) used to lubricate the (oil-injected) screw compressor and, in particular, (partially) penetrates a gearbox chamber in which the gearbox assembly is located. In this way, components of the gearbox assembly, such as the drive shaft and the torsionally flexible gear (as well as the torsionally rigid gear), are (externally) coated with lubricating oil (lubricating oil droplets), which is flung off (radially) during rotation.

[0058] The gear arrangement according to the invention utilizes the advantages of the torsionally flexible gear described above. In particular, the torsionally flexible gear has good stability in the axial and radial directions within the gear arrangement.

[0059] Furthermore, the aforementioned problem is solved in particular by a screw compressor or screw blower comprising a gear arrangement according to the invention. The screw compressor or screw blower preferably comprises a drive motor connected to the drive shaft of the gear arrangement. The screw compressor is preferably oil-lubricated, in particular an oil-injected screw compressor. The screw compressor or screw blower according to the invention utilizes the advantages of the gear arrangement and the torsionally flexible gear described above.

[0060] Furthermore, the aforementioned problem is solved in particular by the use of a torsionally elastic gear according to the invention for vibration damping, preferably torsional vibration damping, in a gear arrangement for connecting a drive motor and a screw compressor or screw blower. Preferably, the lubricating oil used for lubricating the screw compressor is used (via suitable lubricating oil channels) for lubricating the gear, in particular the support sliding surfaces and elastic damping elements.

[0061] Furthermore, the aforementioned problem is solved in particular by the use of a torsionally flexible gear according to the invention for changing natural frequencies, especially for reducing the excitation of natural frequencies, in a drive train of a screw compressor (or screw blower). The drive train comprises, in particular, a drive motor of a screw compressor (or screw blower) and a gearbox assembly for connecting the drive motor and the screw compressor (or screw blower). The torsionally flexible gear can be used to change natural frequencies such that, by using the torsionally flexible gear in the gearbox assembly of the drive train, at least one natural frequency (due to the vibration characteristics of the torsionally flexible gear) shifts into frequency ranges that are less strongly excited during operation, thereby reducing the resonance of the natural frequency during operation.

[0062] Furthermore, the aforementioned task is solved in particular by a method for damping vibrations (torsional vibrations) in the drive of a screw compressor or screw blower, comprising: - Providing a gear arrangement, in particular a gear arrangement according to the invention, with at least one gear stage comprising at least one torsionally flexible gear according to the invention; - Driving a screw compressor or screw blower, in particular a screw compressor or screw blower according to the invention, by operating a drive motor of the screw compressor or screw blower, preferably with variable speed, wherein the drive shaft of the drive motor is coupled to a drive shaft of the screw compressor or screw blower via the gear arrangement, and wherein vibrations occurring, preferably torsional vibrations, are at least partially damped by the torsionally elastic gear.

[0063] Alternatively or additionally to damping vibrations, natural frequencies in the drive train of a screw compressor or screw blower can be modified by providing a gear arrangement with at least one gear stage comprising at least one torsionally flexible gear according to the invention and driving a screw compressor or screw blower, in particular such that the natural frequencies of the gear arrangement or the (entire) drive train shift towards lower frequencies. The excitation of natural frequencies during operation can thereby be reduced. This advantageous effect is achieved by the torsionally flexible transmission of the drive torque of the drive motor of the screw compressor or screw blower through the torsionally flexible gear (relative to a conventional rigid gear).

[0064] As a further process step, the lubrication of at least one (axial and / or radial) support sliding surface of the gear, preferably at least one support disc of the gear, and / or the at least one elastic damping element by lubricating oil can be included, wherein the lubricating oil is preferably (also) used for lubricating the screw compressor (and the entire transmission assembly). The lubricating oil is preferably collected on an axial outer surface of the at least one support disc, preferably by a collecting surface (circumferential groove) extending at least partially along the circumference and, more preferably, by at least one (axial) lubricating oil channel that supplies at least one (axial and / or radial) support sliding surface of the gear and / or the at least one elastic damping element for lubrication.

[0065] The method according to the invention has the same or similar advantages as the torsionally flexible gear described above.

[0066] Exemplary embodiments of the invention are explained in more detail below with reference to the drawings. These show: Fig. 1 a schematic perspective view of a torsionally elastic gear according to the invention in one embodiment; Fig. 2a a schematic front view of the torsionally elastic gear according to Fig. 1 in a first embodiment; Fig. 2b a schematic side view of the first embodiment according to Fig. 2a; Fig. 3a a schematic sectional view according to Fig. 2a along the intersection line AA; Fig. 3b a schematic sectional view according to Fig. 2b along the intersection line BB; Fig. 3c a schematic detail view of section Z in Fig. 3a; Fig. 3D schematic detail view of section Y in Fig. 3a; Fig. 4a a schematic front view of the gear ring part according to Fig. 2a; Fig. 4b a schematic sectional view of the gear ring part according to Fig. 4a along the intersection line CC; Fig. 5a a schematic front view of the hub part according to Fig. 2a; Fig. 5b a schematic sectional view of the hub part according to Fig. 5a along the intersection line DD; Fig. 6a a schematic front view of a support disc in the embodiment according to Fig. 1; Fig. 6b a schematic sectional view of the support disc according to Fig. 6a along the intersection line EE; Fig. 7a a schematic front view of the torsionally elastic gear according to Fig. 1 in a second embodiment; Fig. 7b a schematic side view of the first embodiment according to Fig. 7a; Fig. 8a a schematic sectional view according to Fig. 7a along the intersection line AA; Fig. 8b a schematic sectional view according to Fig. 7b along the intersection line BB; Fig. 8c a schematic detail view of section Z in Fig. 8a; Fig. 8d a schematic detail view of section Y in Fig. 8a; Fig. 9a a schematic front view of the gear ring part according to Fig. 7a; Fig. 9b a schematic sectional view of the gear ring part according to Fig. 9a along the intersection line CC; Fig. 10a a schematic front view of the hub part according to Fig. 7a; Fig. 10b a schematic sectional view of the hub part according to Fig. 10a along the intersection line DD; Fig. 11 a schematic perspective representation of a cylindrical damping element; Fig. 12a a schematic sectional view of a damping element along the section line EE in Fig. 12b in a version with a core and a casing; Fig. 12b a schematic front view of the damping element according to Fig. 12a; Fig. 13a a schematic sectional view of a damping element along the section line EE in Fig. 13b in a version as a hollow cylinder; Fig. 13b a schematic front view of the damping element according to Fig. 13a; Fig. 14 a schematic sectional view of a gear arrangement according to the invention in one embodiment.

[0067] In the following description of the invention, the same reference numerals are used for identical and identically acting elements.

[0068] Fig. Figure 1 shows a torsionally elastic gear 1 according to the invention in a perspective view with an outer gear ring part 20, an inner hub part 10 (in Fig. 1 not visible), a first support disc 50 (in Fig. 1 (not visible) on a first axial end face 3, a second support disc 60 on a second axial end face 4, and a mounting disc 8. The toothing 7 of the gear 1 is designed as helical teeth. The gear 1 is preferably used in a gear arrangement 100 of a screw compressor 300 or a screw blower for vibration damping (see Fig. 14). The embodiments of the gear 1 described below with reference to a screw compressor 300 are also suitable for a gear arrangement for a screw blower.

[0069] The Fig. Figures 2a to 6b show a torsionally elastic gear 1 according to the invention and its components in a first embodiment with damping elements 30, which are designed as polymer damping elements 32, as a first variant of the embodiment according to Fig. 1. The Fig. Figures 7a to 10b show a torsionally elastic gear 1 according to the invention and its components in a second embodiment with damping elements 30, which are designed as wire mesh 31, as a second variant of the embodiment according to Fig. 1. The support discs 50 and 60 are identical in both embodiments. Both embodiments function essentially the same, unless otherwise described.

[0070] The Fig. 4a, Fig. 4b and Fig. 5a, Fig. Figure 5b shows the gear ring part 20 or the hub part 10 according to the first embodiment.

[0071] The Fig. 9a, Fig. 9b and Fig. 10a, Fig. Figure 10b shows the gear ring part 20 or the hub part 10 according to the second embodiment.

[0072] The Fig. 6a, Fig. Figure 6b shows the support disc 60, with the support disc 50 having an identical construction.

[0073] As in the Fig. 2a and Fig. As shown in Figure 2b, the torsionally flexible gear 1 has a hub part 10 made of metal, which serves to connect the gear 1 to a shaft 2 of a gear assembly 100 of a screw compressor 300. The ring gear part 20, also made of metal, has teeth 7, which are designed as helical teeth. The teeth 7 mesh with the teeth of a mating gear 102 of the gear assembly 100 (see Figure 2b). Fig. 14). Axial forces are generated by the helical gearing. The hub part 10 and the ring gear part 20 are slightly rotatable relative to each other in the circumferential direction of the gear 1. Several elastic damping elements 30 (see Fig. 3b and Fig. 8b) are provided for torque transmission and for damping vibrations in the circumferential direction of the gear 1, distributed around the circumference. Between an outer area 12 of the hub part 10 and an inner area 22 of the gear ring part 20, several recessed spaces 40 are formed, in each of which a damping element 30 is detachably received. The damping elements 30 serve to transmit torque between the hub part 10 and the gear ring part 20 and to dampen vibrations. The damping elements 30 could also be referred to as buffer elements. The hub part 10 and gear ring part 20 can be manufactured from a single workpiece, for example, by sintering, wire EDM, or machining.

[0074] Furthermore, gear 1 includes two support discs 50, 60 (see Fig. 3a, Fig. 6a, Fig. 6b and Fig. 8a), which extend radially between the hub part 10 and the gear ring part 20. The support discs 50, 60 are designed for axial and radial support of the gear ring part 20 on the hub part 10. Therefore, each of the support discs 50, 60 has an axial support sliding surface 51, 61 for axially supporting the gear ring part 20 on the hub part 10 (i.e., for transmitting support forces in the axial direction) and at least one radial support sliding surface 52, 62 for radially supporting the gear ring part 20 on the hub part 10 (i.e., for transmitting support forces in the radial direction). The first support disc 50 and the second support disc 60 are arranged opposite each other on both sides of the gear ring part 20 in the axial direction. The first support disc 50 extends radially along the first axial end face 3 of the gear 1 between the hub part 10 and the gear ring part 20. It is designed to provide axial and radial support for the gear ring part 20 on the hub part 10.The hub part 10 has an axial stop surface 16a and a radial centering surface 17a for supporting the first support disc 50. The first support disc 50 has a corresponding first axial stop surface 53 and first radial centering surface 56 for support against the hub part 10. Thus, the axial stop surfaces 16a, 16b of the hub part 10 bear against the axial stop surfaces 53, 63 of the support discs 50, 60. The first support disc 50 has a first axial support sliding surface 51 for sliding axial support of the gear ring part 20 on the hub part 10 and a first radial support sliding surface 52 for sliding radial support of the gear ring part 20 on the hub part 10. The second support disc 60 extends radially along the second axial end face 4 of the gear 1 between the hub part 10 and the gear ring part 20. It is designed to provide axial and radial support for the gear ring part 20 on the hub part 10.The hub part 10 has an axial stop surface 16b and a radial centering surface 17b for supporting the second support disc 60. The second support disc 60 has a corresponding second axial stop surface 63 and a second radial centering surface 66 for support against the hub part 10. Thus, the radial centering surfaces 17a, 17b of the hub part 10 bear against the radial centering surfaces 56, 66 of the support discs 50, 60. The second support disc 60 has a second axial support sliding surface 61 for the sliding axial support of the gear ring part 20 on the hub part 10 and a second radial support sliding surface 62 for the sliding radial support of the gear ring part 20 on the hub part 10. In this respect, the gear is symmetrically constructed.

[0075] The support discs 50, 60 are rigidly connected to the hub part 10, namely clamped against the hub part 10 on both sides via screw connections 9. The first support disc 50 and the second support disc 60 thus bear against axial end faces 13, 14 of the hub part 10. The gear ring part 20 has a lateral circumferential recess 24a, 24b on each of its axial end faces 23a, 23b, into which the support discs 50, 60 are inserted. Axial support sliding surfaces 25a, 25b of the circumferential recesses 24a, 24b bear against the axial support sliding surfaces 51, 61 of the support discs 50, 60. Radial support sliding surfaces 26a, 26b of the circumferential recess 24 lie against the radial support sliding surfaces 52, 62 of the support discs 50, 60.The gear ring section 20 and the hub section 10 can rotate slightly relative to each other in the circumferential direction (micro-movement), whereby the support discs 50, 60, which are rigidly connected to the hub section 10, and the gear ring section 20 slide against each other along the support sliding surfaces 51, 52, 61, 62 (sliding contact). For this purpose, the support sliding surfaces 51, 52, 61, 62 are supplied with lubricating oil. In addition, the support sliding surfaces 51, 52, 61, 62 have a DLC coating.

[0076] From the Fig. Figures 1 to 10b show how the support sliding surfaces 51, 52, 61, 62 are supplied with lubricating oil via lubricating oil channels 71, 72 from an axial support disc outer surface 54, 64. For this purpose, the support discs 50, 60 each have a lubricating oil channel 71, 72 designed as an axial through-bore with an inlet opening 73, 74 and an outlet opening 75, 76, which extends into the axial gap 5 between the support disc 50, 60 and the gear ring part 20. On the axial outer surfaces of the support discs 54, 64, a circumferential radially oriented collecting surface 55, 65 is formed over the entire circumference by an axially projecting circumferential edge, which together with the outer surfaces of the support discs 54, 65 forms a circumferential groove (with a nose-shaped cross-sectional profile) for collecting and distributing lubricating oil, which is flung radially away as lubricating oil droplets when the gear 1 rotates (due to centrifugal force) and hits the collecting surface 55, 65.The gear 1 and the shaft 2, e.g., the drive shaft 201, are wetted by the oil splashing around in the gearbox compartment, which is also used for lubricating the screw compressor 300. The lubricating oil collects in an oil collection area 57, 67 on a radial inner side of the collection surface 55, 65. Through the inlet openings 73, 74 distributed around the circumference, the oil is guided through the lubricating oil channel 71, 72 and through the outlet opening 75, 76 to the axial gap 5.

[0077] The lubricating oil spreads circumferentially in the axial gap 5. Due to centrifugal force, the oil is first driven radially through the axial gap 5 between the gear ring part 20 and the support discs 50, 60 along the axial support sliding surface 51, 61, then guided axially along the radial support sliding surfaces 52, 62, and finally flung back into the gearbox chamber. The lubricating oil also enters the recessed spaces 40 and serves to lubricate the damping elements 30, in particular the contact surfaces of the damping elements 30 with the gear ring part 20, the hub part 10, and the inner surfaces 58, 68 of the support discs 50, 60. If the damping element 30 is designed as a wire mesh 31 (see Fig. 7a to 10b), the lubricating oil also serves to lubricate the rubbing wires of the wire mesh 31. To promote the oil flow within the gear 1, the support discs 50, 60 have a circumferential groove 59, 69 on their axial inner sides 58, 68, and the gear ring part 20 has a circumferential groove 28a, 28b on its axial side 27a, 27b in the area of ​​an axial gap 5 between the support discs 50, 60 and the gear ring part 20 for oil distribution in the circumferential direction. The outlet openings 75, 76 of the lubricating oil channel 71, 72 open into the circumferential groove 59, 69 on the axial inner sides 58, 68 of the support discs 50, 60. The oil lubrication reduces the wear of the support sliding surfaces 51, 52, 61, 62. Lubrication is thus achieved through design measures, namely through the lubricating oil (compressor oil), which also lubricates the screw compressor 300 and the entire gear assembly 100, i.e. in particular the gear transmission with gear stage 101.

[0078] A first variant of the embodiment according to Fig. 1 is in the Fig. Figures 2a to 6b are shown. The damping elements 30 are designed here as polymer damping elements 32, since they comprise a polymer, preferably a thermoplastic elastomer, which preferably has a Shore hardness D in the range of 50 to 65. Some embodiments of the polymer damping elements 32 are shown in the Fig. Figures 11 to 13b illustrate this. In this embodiment of the gear 1, the maximum outer diameter of the hub part 10 is smaller than the minimum inner diameter of the gear ring part 20, so that a circumferential radial gap 6 is formed between the outer circumferential surface 15 of the hub part 10 and the inner circumferential surface 29 of the gear ring part 20. The recesses 40 for receiving the damping elements 30 are formed by radially opposed, substantially semicircular, corresponding recesses in the hub part 10 and the gear ring 20. Thus, several recesses 40 are formed between an outer surface 12 of the hub part 10 and an inner surface 22 of the gear ring part 20. The substantially circular cylindrical recesses 40 are adapted to receive a cylindrical damping element 30.No radial forces are transmitted via the inner hub part 10 of the gear 1 because a radial gap 6 to the outer gear ring part 20 is always present, allowing the gear part 20 to rotate (slightly) relative to the hub part 10. The damping elements 30, 32 are primarily subjected to compressive loads when a torque is transmitted. A total of twelve elastic damping elements 30, 32 are provided.

[0079] A second variant of the embodiment according to Fig. 1 is in the Fig. Figures 7a to 10b are shown, with the support discs 50, 60 as in the Fig. 6a, Fig. 6b are implemented. The damping elements 30 are implemented as wire mesh 31 in this embodiment of the gear 1. The hub part 10 has, in its outer area 12, coupling projections 11a projecting radially outwards and coupling recesses 11b located between them. The gear ring part 20 has, in its inner area 22, coupling projections 21a projecting radially inwards and coupling recesses 21b located between them. The coupling projections 11a of the hub part 10 engage in coupling recesses 21b of the gear ring part 20, and coupling projections 21a of the gear ring part 20 engage in coupling recesses 11b of the hub part 10. A circumferential radial gap 6 is formed between sections of an outer circumferential surface 15 of the hub part 10 and sections of the inner circumferential surface 29 of the gear ring part 20.The essentially cuboid recesses 40 for receiving the damping elements 30, 31 are each formed between a coupling projection 11a of the hub part 10 and a coupling projection 21a of the gear ring part 20. Thus, several recesses 40, in this case a total of twelve, are formed between an outer area 12 of the hub part 10 and an inner area 22 of the gear ring part 20. The wire mesh 31 is pre-tensioned in the circumferential direction of the gear 1 and installed. The damping elements 30, 31 are oriented such that a main manufacturing pressing direction of the wire mesh 31 runs along the circumferential direction of the gear 1. The wire mesh 31 is therefore elastically compressed and loaded (only) along this main manufacturing pressing direction for vibration damping. The damping elements 30, 31 are subjected to compressive loads only when a torque is transmitted. A total of twelve elastic damping elements 30, 31 are provided.

[0080] With regard to oil lubrication, the first embodiment functions according to the Fig. 2a to 6b and the second embodiment according to the Fig. Figures 7a to 10b are essentially the same. Details shown in the figures are transferable to the other embodiment.

[0081] Some embodiments of the polymer damping elements 32 are described in the Fig. 11 to 13b are shown. Fig. Figure 11 shows a circular cylindrical damping element 30 made of one or more polymer materials, as described in the first embodiment according to the Fig. 2a to 6b is used. The polymer materials used are preferably thermoplastic polymers. Various polymer damping elements 32 can be incorporated into a gear 1, in particular alternating around the circumference, in order to achieve desired vibration characteristics, especially damping characteristics, of the gear 1.

[0082] A polymer damping element 32 can be designed as a hollow cylinder with a central cavity 33 (see Fig. 12a, Fig. 12b).

[0083] Alternatively, the polymer damping element 32 can be designed with a core 34 and a casing 35 (see Fig. 13a, Fig. 13b), wherein the core 34 can be made of metal or a polymer material and the cladding 35 can be made of a polymer material. In one embodiment, the core 34 comprises a first polymer, e.g., PA12, with a higher hardness and a cladding 35 with a second polymer with a lower hardness. The material of the cladding 35 can be injection-molded onto the core 34.

[0084] Fig. Figure 14 shows a drive train 400 of a screw compressor 300. The gear arrangement 100 according to the invention, in which a torsionally flexible gear 1 according to the invention is installed, is part of the drive train 400. The gear arrangement 100 according to Fig. Figure 14 comprises a gear stage 101 with the torsionally flexible gear 1 on the drive shaft 201 of the drive motor 200 in one possible embodiment and a conventional, i.e., torsionally rigid, mating gear 102 mounted on the drive shaft 301 of the screw compressor 300. The gear 1 is preferably constructed according to the first or second embodiment described above and has corresponding advantages. The gear 1 is cantilevered on the drive shaft 201 (see the bearing arrangement shown in the drawing). Fig. 14).

[0085] In a gear arrangement 100 according to the invention, a torsionally flexible gear 1 is mounted on a shaft 2, in Fig.14 on the drive shaft 201 (motor shaft) of a drive motor 200 for driving the screw compressor 300. In another embodiment of the gear arrangement 100, the gear 1 could be mounted on the drive shaft 301 (screw rotor shaft) of the screw compressor 300. Instead of the screw compressor 300, a screw blower could also be driven by the drive motor 200.

[0086] The torsionally flexible gear 1, using simple design features, improves the smooth running of an (oil-injected) screw compressor or screw blower, particularly a screw compressor with a cantilevered drive shaft, and reduces acoustic emissions during operation of the (oil-lubricated) screw compressor. Undesired vibrations in the resonance frequency range (natural frequencies) of the drive train of a screw compressor 300 are damped and shifted, especially to lower frequencies. Due to its described design and the damping elements 30, the gear 1 dampens vibrations, especially torsional vibrations, that occur in the drive train of the screw compressor 300. Furthermore, the drive torque can be transmitted smoothly thanks to the torsionally flexible gear.

[0087] The rigid (inelastic) absorption of radial and axial gear forces due to the design of gear 1 prevents deflection of the gear ring 20 in the axial and radial directions. This ensures the precise positioning of the teeth of gear ring part 20 and the torsionally rigid mating gear 102 relative to each other, as required for a gear drive. Due to its axially and radially rigid design, gear 1 is suitable for use in screw compressors with regard to the forces and torques encountered.

[0088] The gear 1 is also suitable for use under the prevailing operating conditions in oil-lubricated screw compressors (temperature, lubricating oil). Through suitable design, in particular material selection, of the damping elements 30 and the described oil lubrication of the gear 1, a long service life is achieved even under the typical operating conditions of an oil-lubricated screw compressor, especially with regard to the resistance of the damping elements 30 to contact with lubricating oil.

[0089] The gearbox assembly 100 for the screw compressor 300 does not require an additional gearbox shaft or a conventional torsionally flexible coupling, which is frequently used in the prior art to dampen vibrations in resonance frequency ranges. This enables a compact design for the screw compressor 300. Reference symbol list: 1 gear 2nd wave 3 first axial face (gear) 4 second axial face (gear) 5 Axial gap 6 radial gap 7. Gearing (helical gearing) 8 Mounting washer 9 screw connection 10 Hub part 11a Coupling projection (hub part) 11b Coupling recess (hub part) 12 Outdoor area 13 first axial end face (hub part) 14 second axial end face (hub part) 15 outer peripheral surface (hub part) 16a, 16b axial stop surface (hub part) 17a, 17b radial centering surface (hub part) 20 Gear ring part 21a Coupling projection (gear ring part) 21b Coupling recess (gear ring part) 22 Interior (gear ring part) 23a, 23b axial end face 24a, 24b Perimeter recess 25a, 25b axial support sliding surface (gear ring part) 26a, 26b radial support sliding surface (gear ring part) 27a, 27b axial side (gear ring part) 28a, 28b Circumferential groove 29 Inner circumferential surface (gear ring part) 30 damping element 31 Wire knitting 32 Polymer damping element 33 Cavity 34 core 35 Sheathing 40 extraction area 50 first support disc 51 first axial support sliding surface (first support disc) 52 first radial support sliding surface (first support disc) 53 first axial stop surface (first support disc) 54, 64 axial support disc outer surface 55, 65 Collection area for lubricating oil 56 first radial centering surface (first support disc) 57, 67 Oil collection area 58, 68 axial inner side 59, 69 Circumferential groove 60 second support disc 61 second axial support sliding surface (second support disc) 62 second radial support sliding surface (second support disc) 63 second axial stop surface (second support disc) 66 second radial centering surface (second support disc) 71, 72 Lubricating oil channel 73, 74 Entrance 75, 76 Outlet opening 100 Gear arrangement 101 gear stage 102 Counter gear 200 drive motor 201 Drive shaft (of the drive motor) 300 screw compressor 301 Drive shaft (of the screw compressor) 400 Powertrain QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 4 112 937 A1 [0005, 0006] WO 2019 / 043469 A1

[0007] WO 2021 / 156778 A1

[0008] WO 2011 / 047807 A1

[0009] AT 501915 A4

[0010] DE 10 2009 058 378 A1

[0011] AT 520740 B1

[0012] EP 3 809 017 A1

[0013] DE 10 2008 013 865 A1

[0014]

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