Efficient spur gear transmission

Abstract

Spur gear transmission 1, comprising at least two spur gears 2 which mesh with each other via a toothing 5, comprising at least one inner housing 10 which encloses at least a part of the spur gears 2 in the circumferential direction and in the direction of the axes of rotation 7, 8 by means of a shell wall 11, wherein an annular gap 12 is formed between the inner housing 10 and the spur gears 2, wherein the inner housing 10 has at least one opening 13, the inner housing 10 encloses at least the majority of the spur gears 2, and wherein the spur gear transmission 1 comprises a wiper device 30, wherein the wiper device 30 is arranged in the direction of rotation 40 in front of the engagement 6 of the spur gears 2, and is designed to receive lubricant or coolant 9 and air from the annular gap 11 and to discharge them from the inner housing 10 through the opening 13.

Description

[0001] The invention relates to a spur gear, comprising at least two spur gears which mesh with each other via a toothing, comprising at least one inner housing which encloses at least a part of the spur gears in the circumferential direction and in the direction of the rotation axes by means of an enveloping wall, wherein an annular gap is formed between the inner housing and the spur gears

[0002] EP 3 368 797 B1 is known from the prior art, which shows a spur gear with two toothed spur gears shielded by an inner housing, which reduces turbulence from air-oil mixtures inside the housing of the spur gear. However, the spur gears are primarily cooled via the surface of the inner housing.

[0003] The object of the invention is to reduce friction losses in the area of ​​engagement of the spur gears in a spur gear by optimizing lubricant or coolant flows. Furthermore, effective cooling of the spur gears in the inner housing is to be enabled, thus providing a particularly efficient spur gear.

[0004] The object is achieved according to the invention by an embodiment according to the independent claim. Further advantageous embodiments of the present invention can be found in the subclaims.

[0005] Furthermore, the object is achieved according to the invention, wherein the inner housing has at least one opening, the inner housing encloses at least the majority of the spur gears and that the spur gear comprises a stripping device, wherein the stripping device is arranged in the direction of rotation before the engagement of the spur gears and is designed to receive lubricant or coolant and air from the annular gap and to discharge it from the inner housing through the opening.

[0006] It is particularly advantageous to remove air, lubricant, and / or coolant prior to meshing, as this reduces friction in the area where the spur gears mesh. The meshing of the spur gears creates excess pressure in the area prior to meshing, as entrained air and / or lubricant or coolant are forced through the meshing, thus increasing friction.

[0007] Furthermore, a spur gear is advantageous, wherein the stripping device comprises at least one application nozzle on the side facing the spur gears and / or the engagement, suitable for applying lubricant or coolant to the spur gears in the area of ​​the engagement.

[0008] For lubrication and / or additional cooling of the gear surfaces of the spur gears, it is advantageous if fresh (or cooled) lubricant or coolant is applied directly to the gear surfaces using a nozzle immediately before engagement.

[0009] Also advantageous is a spur gear, wherein a cooling device is arranged in the direction of rotation after the engagement, wherein the cooling device comprises at least two application nozzles, wherein the cooling device is designed to apply lubricant or coolant to both spur gears.

[0010] Applying lubricant or coolant is particularly advantageous in the direction of rotation after the gear surfaces mesh, as on this side, the lubricant or coolant directly reaches the part of the gear surface that is in contact and / or mesh with the other gear surface. This part of the gear surface is also referred to as the load flank. Applying lubricant or coolant to the load flank can both create a uniform lubricating film and enable particularly effective cooling, as the load flanks are at a high temperature due to the direct contact.

[0011] Further advantageous is a spur gear wherein the stripping device and / or the cooling device comprises at least two further flat nozzles, designed to introduce lubricant or coolant into the space between the inner housing and the spur gear, in particular into the area of ​​the gear flanks.

[0012] Using flat nozzles, lubricant or coolant can be introduced directly into the space between the inner housing and the spur gear. The temperature generated by friction during meshing can also be dissipated by coolant via the tooth flanks and / or the sides of the spur gears, which do not have gear surfaces. Applying coolant over a large area using a flat nozzle is particularly advantageous because the surface contact ensures efficient heat transfer from the spur gear to the coolant. A mineral or synthetic oil is usually used as a lubricant or coolant, which fulfills both the task of lubricating and cooling the spur gears. Cooling is necessary because the spur gears quickly reach an elevated temperature when large loads are transmitted and / or speeds are high.Elevated temperatures are considered temperatures above 100°C, especially above 120°C, and especially temperatures on the surface of the gears in the range of 120°C - 300°C. At elevated temperatures, thermal expansion can lead to meshing play and thus increased wear on the gear surfaces. Cooling can generally be achieved via convection and / or heat conduction, with heat conduction from the spur gears to the lubricant or coolant having proven particularly effective.

[0013] A spur gear is also advantageous, wherein a further stripping device is arranged at at least one further opening in the inner housing, designed to discharge lubricant or coolant from the inner housing before it enters the annular gap.

[0014] To minimize friction between the inner housing and the spur gears, it can be advantageous to divert some of the entrained lubricant or coolant, along with any entrained air, from the annular gap. In doing so, an optimal operating point must always be balanced between effective cooling and low friction. Therefore, depending on the design of the spur gear, it has been shown that an additional opening in the inner housing with a scraper device is advantageous. The scraper devices can also advantageously be designed as blades.

[0015] Further advantageous is a spur gear transmission, wherein the inner housing has at least one further opening which is arranged downstream of the cooling device in the direction of rotation, wherein the opening has at least the width of the spur gears and wherein the opening is arranged at an angle α in the running direction of 30° - 270° downstream of the engagement.

[0016] The scraper device can advantageously be arranged tangentially in the running direction of the spur gears, since any lubricant or coolant adhering to or entrained on the gear surfaces is thrown off tangentially due to mass inertia. This further reduces friction in the annular gap between the spur gear and the inner housing, and increases the efficiency of the spur gear. To ensure that the lubricant or coolant has sufficient residence time for effective heat transfer, the additional opening should be arranged at an angle α greater than 30° after the engagement. An angle α of 45° to 180° is particularly advantageous, as this achieves a good compromise between effective cooling and reduced friction or improved flow guidance of the lubricant or coolant.

[0017] Further advantageous is a spur gear comprising an outer gear housing, wherein the at least one stripping device is fastened to the outer gear housing and wherein the stripping device has a distance of between 1 mm - 10 mm from the gear surfaces.

[0018] At high speeds and high transmitted torques, the lubricant or coolant reaches high flow velocities. This means that wiper devices are subjected to high loads due to contact with the lubricant or coolant and the entrained air. At the same time, precise alignment of the wiper device close to the gear surfaces is important to achieve an effective wiping effect and to effectively wipe off any entrained lubricant or coolant and air. It is particularly advantageous to mount the wiper device on a stable outer housing in an adjustable manner. This also helps reduce vibrations on the wiper device. Furthermore, advantageous and secure mounting of the wiper device is possible at a distance of 1 mm - 10 mm, in particular at a distance of 2 mm - 7 mm, which achieves a particularly effective wiping effect.The assembly can be carried out by screwing in or by means of an adjusting device, for example including some intermediate pieces.

[0019] Further advantageous is a spur gear comprising an outer gear housing, wherein a cooling device arranged after the engagement in the direction of rotation is fastened to the outer gear housing.

[0020] The cooling device can advantageously be mounted directly to an external housing, as this improves mechanical stability. Furthermore, the cooling device can be supplied with cooled lubricant or coolant directly from outside the spur gear via a pipeline. The pipeline itself can act as a support structure to hold the cooling device in the gear housing.

[0021] Also advantageous is a spur gear comprising a first spur gear and a second spur gear, the two spur gears being in engagement with one another via double helical gearing, and a distance being formed between the double helical gearings in the circumferential direction of the spur gears, the stripping device comprising a central web which is designed to engage in the distance in the circumferential direction, the stripping device being designed to also remove lubricant or coolant from the area between the gearings.

[0022] The gap between the teeth of a double helical gear can allow a large amount of lubricant and coolant to pass through during engagement, which is particularly disadvantageous if, in the direction of rotation after engagement, a cooling device applies cooled lubricant or coolant in the opposite flow direction. It is therefore particularly advantageous if the wiping device includes a central web that achieves the wiping effect in the direction of rotation before engagement, even in the gap between the double helical gears.

[0023] A spur gear unit is also advantageous, wherein the inner housing encloses at least 270° of the circumferential surface and the end faces of both spur gears. The end faces are the surfaces that extend from the circumference to the axle, shaft or bearing of the spur gears. An enclosure of 270° corresponds to an enclosure of at least 75% of the inner housing. The space between the spur gears can also be enclosed by the inner housing, although the shape of the inner housing does not have to follow the shape of the spur gears. The inner housing therefore encloses both spur gears together, enclosing at least 75% of the free surface of the spur gears. The openings in the inner housing only open up a maximum of 25% of the inner housing.

[0024] A spur gear is also advantageous, with the annular gap between the spur gear tooth surfaces and the inner housing having a dimension in the radial direction of 2 mm - 25 mm.

[0025] The inner housing advantageously encloses the outer surface of both spur gears at a distance of 2 mm - 25 mm. The annular gap is particularly advantageously designed in a range of 5 mm - 15 mm, as the flow-guiding effect is particularly advantageous and low-friction here. The inner housing not only encloses the outer surface of the spur gears, but also a significant portion of the side surfaces, as well as the area of ​​the end faces and optionally and advantageously also the area of ​​the end faces up to the bearing, the shaft or the bearing block. Furthermore, the inner housing advantageously and optionally also encloses the area between the two spur gears, whereby openings can also be arranged in this area. The inner housing can be made up of several parts or of a large number of segments and is attached to the bearing block or an outer housing. The inner housing can also be securely attached using additional built-in components or brackets.

[0026] Guides or lines for the lubricant or coolant are also advantageously arranged between the inner housing and the transmission housing. Furthermore, the transmission housing advantageously includes an oil sump in its lower area, which is connected to the lubricant or coolant cooling system.

[0027] The invention is explained below with reference to the figures. The figures show in detail: Fig. 1: Illustration of spur gear with cooling device Fig. 2: Schematic representation with three openings Fig. 3: Illustration of spur gear with double helical gearing Fig. 4: Illustration of spur gear with stripping device

[0028] Fig. 1 shows a not-to-scale schematic partial sectional view of a spur gear 1 with a cooling device 20 and a stripping device 30. The spur gear 1 comprises two spur gears 2, which are shown as the first spur gear 3 and the second spur gear 4. The spur gears 2 are in engagement 6 with each other, wherein a torque introduced via the first axis of rotation 7 is transmitted via the first spur gear 3 via the engagement 6 to the second spur gear 4 and thus to the second axis of rotation 8, or vice versa. The direction of rotation 40 is shown clockwise by an arrow for the first spur gear 3, wherein the second spur gear 4 thus rotates counterclockwise; here too, a reverse arrangement is possible. In the area which comes after the engagement 6 in the direction of rotation 40, a cooling device 20 is arranged, which is designed to apply lubricant or coolant 9 to the gear surfaces 31 of the spur gears 2.The cooling device 20 comprises at least four rows of application nozzles 21, which apply lubricant or coolant 9 to both spur gears 2 across the width of the gear surfaces 31. Furthermore, the cooling device 20 comprises at least four flat nozzles 22, which are designed to introduce lubricant or coolant 9 into the gap between gear flanks 32 and inner housing 10 on both sides. The inner housing 10 is slightly widened in the region of the opening 13 in the tangential direction of the spur gears 2 so that sufficient lubricant or coolant 9 can enter the annular gap 12. The spur gear 1 comprises a scraper device 30, which is designed to discharge lubricant and coolant 9, which is carried in the annular gap 12, from the inner housing via at least one further opening 13.In the area after the wiper device, there is also an additional opening 13 to further reduce the pressure in the area before the engagement 6 and to remove accumulated air and / or lubricant and coolant mist or residues from the inner housing 10. This significantly reduces turbulence and the associated friction in the area of ​​the engagement 6.

[0029] Fig. 2 shows a schematic representation of a spur gear 1, wherein the inner housing 10 comprises three openings 13 through which a supply and discharge of lubricant or coolant 9 takes place. The openings 13 thus allow effective cooling of the spur gears 2, wherein in particular the gear surfaces 31 and gear flanks 32 are cooled by wetting with lubricant and coolant 9. In the opening 13, which is arranged in the direction of rotation 40 immediately after the engagement 6 of the spur gears 2, lubricant and coolant 9 is introduced by means of a cooling device 20. It is particularly advantageous to introduce lubricant and coolant 9 in the direction of rotation 40 after the engagement 6, since a vacuum zone is created here by the movement of the spur gears apart. The cooling device 20 comprises a plurality of application nozzles 21, which are designed to apply lubricant and coolant 9 to the gear surfaces 31.Furthermore, the cooling device 20 comprises an optional flat nozzle 22, which is designed to introduce lubricant and coolant 9 onto the gear flanks 32, i.e. into the gap between the spur gear 2 and the inner housing 10. The lubricant and coolant 9 is transported towards the annular gap 12 by centrifugal forces during operation of the spur gear, with a cooling effect occurring through energy transfer from the spur gear 2 to the lubricant and coolant 9. In the direction of rotation 40 there is a further opening 13 which is designed to discharge lubricant and coolant 9 from the annular gap 12 and thus from the inner housing 10. This further opening 13 is advantageously arranged 45° - 180° in the direction of rotation 40 after the first opening; such a further opening can also be arranged on the second spur gear 4 (not shown).This further opening 13 comprises a scraper blade 34 in order to further reduce the amount of lubricant and coolant remaining in the annular gap. The inner housing 10, which is only shown schematically as a line in this figure, also comprises an opening 13 in the area above the engagement 6 of the two spur gears 2. An optional scraper device 30 is arranged in this opening 13 and is designed to effectively drain away lubricant and coolant 9 that is carried in the annular gap 12, so that only a minimized amount of lubricant and coolant 9 reaches the engagement 6 of the two spur gears 2. The scraper device 30 can optionally comprise a schematically shown application nozzle 21 in order to specifically apply some lubricant and coolant 9 to the gear surfaces 31 in the area of ​​the engagement 6.

[0030] Fig. Figure 3 shows a not-to-scale schematic partial sectional view of a spur gear 1 with a cooling device 10 and a stripping device 30, wherein the gear represents spur gears 2 with a double helical gearing. The spur gear 1 comprises two spur gears 2, wherein the spur gears 2 mesh with one another by means of a toothing 5. The engagement 6 takes place via the toothing 5, which is designed, for example, as a double helical gear in this figure. The spur gears 2 comprise a first spur gear 3, which is arranged to rotate about a first axis of rotation 7, and a second spur gear 4, which is arranged to rotate about a second axis of rotation 8, wherein the first spur gear 3 drives the second spur gear 4, or vice versa. The direction of rotation 40 of the spur gears 2, 3, 4 is indicated by arrows.The spur gears are largely surrounded by at least one inner housing 10, which comprises an envelope wall 11 arranged in a ring around the spur gears 2 and largely encloses the spur gears at a close distance. In the area in the direction of rotation 40 upstream of the engagement 6 there is a stripping device 30, which is suitable for discharging lubricant and coolant 9 entrained in the annular gap 12 through an opening 13 from the inner housing 10 and from the annular gap 12. The stripping device 30 comprises a central web 33, designed to achieve efficient stripping between the gears 5 in the case of double helical gearing. The central web 33 engages in the radially formed intermediate space between the gears 5 or between the gear surfaces 31 of the double helical gearing.

[0031] Fig.4 shows a not-to-scale schematic partial sectional view of a spur gear 1, comprising two intermeshing spur gears 2, 3, 4, a stripping device 30, and a cooling device 20. The cooling device 20 comprises a plurality of application nozzles 21 designed to apply lubricant and coolant 9 to the surface of the spur gears 2, wherein the application advantageously takes place in the area of ​​the engagement 6, in particular in the disengagement of the gearings 5, since a negative pressure is created there due to the flow dynamics of the lubricant and coolant 9 and the ambient air. The negative pressure thus allows the lubricant and coolant 9 to wet the gear surfaces 31 particularly effectively. The engagement 6 is the area in which the gearing 5 of the spur gears 2 are in contact with one another. The side on which the gears of the engagement 6, which are moved apart again in the direction of rotation 40, is also called the disengagement.The inner housing 10 also encloses the gear flanks 32 up to the shafts or bearings of the rotary axes 7, 8. Above the meshing point, air, lubricant, and / or coolant 9 are discharged from the inner housing via the scraper device 30 through another opening 13. In this way, friction is reduced by the flow of the lubricant or coolant 9 in the area before the meshing point 6 and in the area of ​​the meshing point 6 itself. This allows friction losses to be reduced, while the lubricant or coolant 9 can still achieve its cooling function through sufficient contact time on the gear surfaces 31. List of reference symbols 1 spur gear 2 spur gear 3 first spur gear 4 second spur gear 5 Gearing 6 Intervention 7 first axis of rotation 8 second axis of rotation 9 Lubricant or coolant 10 inner housing 11 Envelope wall 12 Annular gap 13 Opening 14 Gearbox housing 20 Cooling device 21 Application nozzle 22 Flat nozzle 30 scraper device 31 gear surfaces 32 tooth flanks 33 Central bridge 34 scraper blade 40 Direction of rotation α angle QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] EP 3 368 797 B1

[0002]

Claims

[1] Spur gear 1, comprising at least two spur gears 2, which are meshingly engaged 6 with each other via a toothing 5, comprising at least one inner housing 10, which by means of an enveloping wall 11 encloses at least a part of the spur gears 2 in the circumferential direction and in the direction of the axes of rotation 7, 8, wherein an annular gap 12 is formed between the inner housing 10 and the spur gears 2 characterized by that the inner housing 10 has at least one opening 13, the inner housing 10 encloses at least the majority of the spur gears 2 and that spur gear 1 comprises a stripping device 30, wherein the stripping device is arranged in the direction of rotation 40 in front of the engagement 6 of the spur gears 2, and is designed to receive lubricant or coolant 9 and air from the annular gap 11 and to discharge them from the inner housing 10 through the opening 13. [2] Spur gear 1 according to claim 1, characterized bythat the stripping device 30 comprises at least one application nozzle 21 on the side facing the spur gears 2 and / or the engagement 6, suitable for applying lubricant or coolant 9 to the spur gears 2 in the region of the engagement 6. [3] Spur gear 1 according to claim 1 or claim 2, characterized by that in the direction of rotation 40 after the engagement 6 a cooling device 20 is arranged, wherein the cooling device 20 comprises at least two application nozzles 21, wherein the cooling device 20 is designed to apply lubricant or coolant 9 to both spur gears 2. [4] Spur gear 1 according to one of the preceding claims, characterized by that the stripping device 30 and / or the cooling device 20 comprises at least two further application nozzles 6, in particular flat jet nozzles 23, designed to introduce lubricant or coolant 9 into the space between the inner housing 10 and the spur gear 2, in particular into the area of the gear flanks 32. [5] Spur gear 1 according to one of the preceding claims, characterized by that a further stripping device 30 is arranged at at least one further opening 13 in the inner housing 10, designed to discharge lubricant or coolant 9 from the inner housing 10 before it enters the annular gap 12. [6] Spur gear 1 according to one of the preceding claims, characterized by that the inner housing 10 has at least one further opening 13 which is arranged after the cooling device 20 in the direction of rotation 40, wherein the opening 13 has at least the width of the spur gears 2 and wherein the opening 13 is arranged at an angle α in the running direction 30° - 270° after the engagement. [7] Spur gear 1 according to one of the preceding claims comprising an outer gear housing 14, characterized bythat the at least one stripping device 30 is fastened to the outer gear housing 14, wherein the stripping device 30 has a distance of between 1 mm - 10 mm from the spur gears 2. [8] Spur gear 1 according to one of the preceding claims comprising an outer gear housing 14, characterized by that a cooling device 20 arranged in the direction of rotation 40 after the engagement 6 is fastened to the outer gear housing 14. [9] Spur gear 1 according to one of the preceding claims comprising a first spur gear and a second spur gear, wherein the two spur gears are in engagement with each other via a double helical gearing and wherein a distance is formed between the double helical gearings in the circumferential direction of the spur gears, characterized bythat the stripping device comprises a central web which is designed to engage in the distance in the circumferential direction, wherein the stripping device is designed to also remove lubricant or coolant from the area between the gears. [10] Spur gear 1 according to one of the preceding claims, characterized by that the inner housing encloses at least 270° of the circumferential surface and the end faces of both spur gears. [11] Spur gear 1 according to one of the preceding claims, characterized by that the annular gap between the spur gear tooth surfaces and the inner housing has a dimension in radial direction of 2 mm - 25 mm.

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